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Monera () (Greek - μονήρης (monḗrēs), "single", "solitary") is a kingdom that contains unicellular organisms with a prokaryotic cell organization (having no nuclear membrane), such as bacteria. They are single-celled organisms with no true nuclear membrane (prokaryotic organisms). The taxon was first proposed as a phylum by Ernst Haeckel in 1866. Subsequently, the phylum was elevated to the rank of kingdom in 1925 by Édouard Chatton. The last commonly accepted mega-classification with the taxon was the five-kingdom classification system established by Robert Whittaker in 1969. Under the three-domain system of taxonomy, introduced by Carl Woese in 1977, which reflects the evolutionary history of life, the organisms found in kingdom have been divided into two domains, Archaea and Bacteria (with Eukarya as the third domain). Furthermore, the taxon is paraphyletic (does not include all descendants of their most-recent common ancestor), as Archaea and Eukarya are currently believed to be more closely related than either is to Bacteria. The term "moneran" is the informal name of members of this group and is still sometimes used (as is the term "prokaryote") to denote a member of either domain. Most bacteria were classified under Monera; however, some Cyanobacteria (often called the blue-green algae) were initially classified under Plantae due to their ability to photosynthesize. Traditionally the natural world was classified as animal, vegetable, or mineral as in Systema Naturae | Biology | https://en.wikipedia.org/wiki?curid=19172199 | Monera | 140,563 |
Monera After the development of the microscope, attempts were made to fit microscopic organisms into either the plant or animal kingdoms. In 1675, Antonie van Leeuwenhoek discovered bacteria and called them "animalcules", assigning them to the class Vermes of the Animalia. Due to the limited tools — the sole references for this group were shape, behaviour, and habitat — the description of genera and their classification was extremely limited, which was accentuated by the perceived lack of importance of the group. Ten years after "The Origin of Species" by Charles Darwin, in 1866 Ernst Haeckel, a supporter of evolution, proposed a three-kingdom system that added the Protista as a new kingdom that contained most microscopic organisms. One of his eight major divisions of Protista was composed of the monerans (called Moneres by Haeckel), which he defined as completely structure-less and homogeneous organisms, consisting only of a piece of plasma. Haeckel's included not only bacterial groups of early discovery but also several small eukaryotic organisms; in fact the genus Vibrio is the only bacterial genus explicitly assigned to the phylum, while others are mentioned indirectly, which led Copeland to speculate that Haeckel considered all bacteria to belong to the genus Vibrio, ignoring other bacterial genera. One notable exception were the members of the modern phylum Cyanobacteria, such as "Nostoc", which were placed in the phylum Archephyta of Algae (vide infra: Blue-green algae) | Biology | https://en.wikipedia.org/wiki?curid=19172199 | Monera | 140,564 |
Monera The Neolatin noun and the German noun Moneren/Moneres are derived from the ancient Greek noun "moneres", which Haeckel stated meant "simple"; however, it actually means "single, solitary". Haeckel also describes the protist genus Monas in the two pages about in his 1866 book. The informal name of a member of the was initially moneron, but later moneran was used. Due to its lack of features, the phylum was not fully subdivided, but the genera therein were divided into two groups: Like Protista, the classification was not fully followed at first and several different ranks were used and located with animals, plants, protists or fungi. Furthermore, Haeckel's classification lacked specificity and was not exhaustive — it in fact covers only a few pages—, consequently a lot of confusion arose even to the point that the did not contain bacterial genera and others according to Huxley. They were first recognized as a kingdom by Enderlein in 1925 (Bakterien-Cyclogenie. de Gruyter, Berlin). The most popular scheme was created in 1859 by C. Von Nägeli who classified non-phototrophic Bacteria as the class Schizomycetes. The class Schizomycetes was then emended by Walter Migula (along with the coinage of the genus "Pseudomonas" in 1894) and others. This term was in dominant use even in 1916 as reported by Robert Earle Buchanan, as it had priority over other terms such as Monera | Biology | https://en.wikipedia.org/wiki?curid=19172199 | Monera | 140,565 |
Monera However, starting with Ferdinand Cohn in 1872 the term "bacteria" (or in German "") became prominently used to informally describe this group of species without a nucleus: Bacterium was in fact a genus created in 1828 by Christian Gottfried Ehrenberg Additionally, Cohn divided the bacteria according to shape namely: Successively, Cohn created the Schizophyta of Plants, which contained the non-photrophic bacteria in the family Schizomycetes and the phototrophic bacteria (blue green algae/Cyanobacteria) in the Schizophyceae This union of blue green algae and Bacteria was much later followed by Haeckel, who classified the two families in a revised phylum in the Protista. Stanier and van Neil (1941, The main outlines of bacterial classification. J Bacteriol 42: 437- 466) recognized the Kingdom with two phyla, Myxophyta and Schizomycetae, the latter comprising classes Eubacteriae (3 orders), Myxobacteriae (1 order), and Spirochetae (1 order); Bisset (1962, Bacteria, 2nd ed., Livingston, London) distinguished 1 class and 4 orders: Eubacteriales, Actinomycetales, Streptomycetales, and Flexibacteriales; Orla-Jensen (1909, Die Hauptlinien des naturalischen Bakteriensystems nebst einer Ubersicht der Garungsphenomene. Zentr. Bakt. Parasitenk., II, 22: 305-346) and Bergey et al (1925, Bergey's Manual of Determinative Bacteriology, Baltimore : Williams & Wilkins Co.) with many subsequent editions) also presented classifications | Biology | https://en.wikipedia.org/wiki?curid=19172199 | Monera | 140,566 |
Monera The term became well established in the 20s and 30s when to rightfully increase the importance of the difference between species with a nucleus and without. In 1925, Édouard Chatton divided all living organisms into two empires Prokaryotes and Eukaryotes: the Kingdom being the sole member of the Prokaryotes empire. The anthropic importance of the crown group of animals, plants and fungi was hard to depose; consequently, several other megaclassification schemes ignored on the empire rank but maintained the kingdom consisting of bacteria, such Copeland in 1938 and Whittaker in 1969. The latter classification system was widely followed, in which Robert Whittaker proposed a five kingdom system for classification of living organisms. Whittaker's system placed most single celled organisms into either the prokaryotic or the eukaryotic Protista. The other three kingdoms in his system were the eukaryotic Fungi, Animalia, and Plantae. Whittaker, however, did not believe that all his kingdoms were monophyletic. Whittaker subdivided the kingdom into two branches containing several phyla: Alternative commonly followed subdivision systems were based on Gram stains. This culminated in the Gibbons and Murray classification of 1978: In 1977, a PNAS paper by Carl Woese and George Fox demonstrated that the archaea (initially called archaebacteria) are not significantly closer in relationship to the bacteria than they are to eukaryotes | Biology | https://en.wikipedia.org/wiki?curid=19172199 | Monera | 140,567 |
Monera The paper received front-page coverage in "The New York Times", and great controversy initially. The conclusions have since become accepted, leading to replacement of the kingdom with the two domains Bacteria and Archaea. A minority of scientists, including Thomas Cavalier-Smith, continue to reject the widely accepted division between these two groups. Cavalier-Smith has published classifications in which the archaebacteria are part of a subkingdom of the Kingdom Bacteria. Although it was generally accepted that one could distinguish prokaryotes from eukaryotes on the basis of the presence of a nucleus, mitosis versus binary fission as a way of reproducing, size, and other traits, the monophyly of the kingdom (or for that matter, whether classification should be according to phylogeny) was controversial for many decades. Although distinguishing between prokaryotes from eukaryotes as a fundamental distinction is often credited to a 1937 paper by Édouard Chatton (little noted until 1962), he did not emphasize this distinction more than other biologists of his era. Roger Stanier and C. B. van Niel believed that the bacteria (a term which at the time did not include blue-green algae) and the blue-green algae had a single origin, a conviction that culminated in Stanier writing in a letter in 1970, "I think it is now quite evident that the blue-green algae are not distinguishable from bacteria by any fundamental feature of their cellular organization". Other researchers, such as E. G | Biology | https://en.wikipedia.org/wiki?curid=19172199 | Monera | 140,568 |
Monera Pringsheim writing in 1949, suspected separate origins for bacteria and blue-green algae. In 1974, the influential "Bergey's Manual" published a new edition coining the term cyanobacteria to refer to what had been called blue-green algae, marking the acceptance of this group within the Monera. Monerans are a group of organisms having prokaryotic structure. Archaea differ from Bacteria in having a different 16Ssrna. They also have a different cell wall structure. | Biology | https://en.wikipedia.org/wiki?curid=19172199 | Monera | 140,569 |
Prokaryote A prokaryote is a unicellular organism that lacks a membrane-bound nucleus, mitochondria, or any other membrane-bound organelle. The word "prokaryote" comes from the Greek (, 'before') and (, 'nut' or 'kernel'). Prokaryotes are divided into two domains, Archaea and Bacteria. Organisms with nuclei and other organelles are placed in the third domain, Eukaryota. Prokaryotes are asexual, reproducing without fusion of gametes. The first organisms are thought to have been prokaryotes. In prokaryotes, all of the intracellular water-soluble components - (proteins, DNA and metabolites) are located in the cytoplasm enclosed by the cell membrane, rather than in separate cellular compartments. Bacteria, however, do possess protein-based microcompartments, which are thought to act as primitive organelles enclosed in protein shells. Some prokaryotes, such as cyanobacteria, may form large colonies. Others, such as myxobacteria, have multicellular stages in their life cycles. Molecular studies have provided insight into the evolution and interrelationships of the three domains of life. Eukaryotic cells have a well defined membrane-bound nucleus (containing chromosomal DNA) and other organelles including mitochondria. The division between prokaryotes and eukaryotes reflects the existence of two very different levels of cellular organization. Distinctive types of prokaryotes include extremophiles and methanogens; these are common in some extreme environments | Biology | https://en.wikipedia.org/wiki?curid=19172225 | Prokaryote | 140,570 |
Prokaryote The division between prokaryotes and eukaryotes was firmly established by the microbiologists Roger Stanier and C. B. van Niel in their 1962 paper "The concept of a bacterium" (though spelled procaryote and eucaryote there). That paper cites Édouard Chatton's 1937 book "Titres et Travaux Scientifiques" for using those terms and recognizing the distinction. One reason for this classification was so that what was then often called blue-green algae (now called cyanobacteria) would not be classified as plants but grouped with bacteria. Prokaryotes have a prokaryotic cytoskeleton that is more primitive than that of the eukaryotes. Besides homologues of actin and tubulin (MreB and FtsZ), the helically arranged building-block of the flagellum, flagellin, is one of the most significant cytoskeletal proteins of bacteria, as it provides structural backgrounds of chemotaxis, the basic cell physiological response of bacteria. At least some prokaryotes also contain intracellular structures that can be seen as primitive organelles. Membranous organelles (or intracellular membranes) are known in some groups of prokaryotes, such as vacuoles or membrane systems devoted to special metabolic properties, such as photosynthesis or chemolithotrophy. In addition, some species also contain carbohydrate-enclosed microcompartments, which have distinct physiological roles (e.g. carboxysomes or gas vacuoles). Most prokaryotes are between 1 µm and 10 µm, but they can vary in size from 0 | Biology | https://en.wikipedia.org/wiki?curid=19172225 | Prokaryote | 140,571 |
Prokaryote 2 µm ("Mycoplasma genitalium") to 750 µm ("Thiomargarita namibiensis"). Prokaryotic cells have various shapes; the four basic shapes of bacteria are: The archaeon Haloquadratum has flat square-shaped cells. Bacteria and archaea reproduce through asexual reproduction, usually by binary fission. Genetic exchange and recombination still occur, but this is a form of horizontal gene transfer and is not a replicative process, simply involving the transference of DNA between two cells, as in bacterial conjugation. DNA transfer between prokaryotic cells occurs in bacteria and archaea, although it has been mainly studied in bacteria. In bacteria, gene transfer occurs by three processes. These are (1) bacterial virus (bacteriophage)-mediated transduction, (2) plasmid-mediated conjugation, and (3) natural transformation. Transduction of bacterial genes by bacteriophage appears to reflect an occasional error during intracellular assembly of virus particles, rather than an adaptation of the host bacteria. The transfer of bacterial DNA is under the control of the bacteriophage's genes rather than bacterial genes. Conjugation in the well-studied "E. coli" system is controlled by plasmid genes, and is an adaptation for distributing copies of a plasmid from one bacterial host to another. Infrequently during this process, a plasmid may integrate into the host bacterial chromosome, and subsequently transfer part of the host bacterial DNA to another bacterium | Biology | https://en.wikipedia.org/wiki?curid=19172225 | Prokaryote | 140,572 |
Prokaryote Plasmid mediated transfer of host bacterial DNA (conjugation) also appears to be an accidental process rather than a bacterial adaptation. Natural bacterial transformation involves the transfer of DNA from one bacterium to another through the intervening medium. Unlike transduction and conjugation, transformation is clearly a bacterial adaptation for DNA transfer, because it depends on numerous bacterial gene products that specifically interact to perform this complex process. For a bacterium to bind, take up and recombine donor DNA into its own chromosome, it must first enter a special physiological state called competence. About 40 genes are required in "Bacillus subtilis" for the development of competence. The length of DNA transferred during "B. subtilis" transformation can be as much as a third to the whole chromosome. Transformation is a common mode of DNA transfer, and 67 prokaryotic species are thus far known to be naturally competent for transformation. Among archaea, "Halobacterium volcanii" forms cytoplasmic bridges between cells that appear to be used for transfer of DNA from one cell to another. Another archaeon, "Sulfolobus solfataricus", transfers DNA between cells by direct contact. Frols et al. found that exposure of "S. solfataricus" to DNA damaging agents induces cellular aggregation, and suggested that cellular aggregation may enhance DNA transfer among cells to provide increased repair of damaged DNA via homologous recombination | Biology | https://en.wikipedia.org/wiki?curid=19172225 | Prokaryote | 140,573 |
Prokaryote While prokaryotes are considered strictly unicellular, most can form stable aggregate communities. When such communities are encased in a stabilizing polymer matrix ("slime"), they may be called "biofilms". Cells in biofilms often show distinct patterns of gene expression (phenotypic differentiation) in time and space. Also, as with multicellular eukaryotes, these changes in expression often appear to result from cell-to-cell signaling, a phenomenon known as quorum sensing. Biofilms may be highly heterogeneous and structurally complex and may attach to solid surfaces, or exist at liquid-air interfaces, or potentially even liquid-liquid interfaces. Bacterial biofilms are often made up of microcolonies (approximately dome-shaped masses of bacteria and matrix) separated by "voids" through which the medium (e.g., water) may flow easily. The microcolonies may join together above the substratum to form a continuous layer, closing the network of channels separating microcolonies. This structural complexity—combined with observations that oxygen limitation (a ubiquitous challenge for anything growing in size beyond the scale of diffusion) is at least partially eased by movement of medium throughout the biofilm—has led some to speculate that this may constitute a circulatory system and many researchers have started calling prokaryotic communities multicellular (for example ) | Biology | https://en.wikipedia.org/wiki?curid=19172225 | Prokaryote | 140,574 |
Prokaryote Differential cell expression, collective behavior, signaling, programmed cell death, and (in some cases) discrete biological dispersal events all seem to point in this direction. However, these colonies are seldom if ever founded by a single founder (in the way that animals and plants are founded by single cells), which presents a number of theoretical issues. Most explanations of co-operation and the evolution of multicellularity have focused on high relatedness between members of a group (or colony, or whole organism). If a copy of a gene is present in all members of a group, behaviors that promote cooperation between members may permit those members to have (on average) greater fitness than a similar group of selfish individuals (see inclusive fitness and Hamilton's rule). Should these instances of prokaryotic sociality prove to be the rule rather than the exception, it would have serious implications for the way we view prokaryotes in general, and the way we deal with them in medicine. Bacterial biofilms may be 100 times more resistant to antibiotics than free-living unicells and may be nearly impossible to remove from surfaces once they have colonized them. Other aspects of bacterial cooperation—such as bacterial conjugation and quorum-sensing-mediated pathogenicity, present additional challenges to researchers and medical professionals seeking to treat the associated diseases. Prokaryotes have diversified greatly throughout their long existence | Biology | https://en.wikipedia.org/wiki?curid=19172225 | Prokaryote | 140,575 |
Prokaryote The metabolism of prokaryotes is far more varied than that of eukaryotes, leading to many highly distinct prokaryotic types. For example, in addition to using photosynthesis or organic compounds for energy, as eukaryotes do, prokaryotes may obtain energy from inorganic compounds such as hydrogen sulfide. This enables prokaryotes to thrive in harsh environments as cold as the snow surface of Antarctica, studied in cryobiology, or as hot as undersea hydrothermal vents and land-based hot springs. Prokaryotes live in nearly all environments on Earth. Some archaea and bacteria are extremophiles, thriving in harsh conditions, such as high temperatures (thermophiles) or high salinity (halophiles). Many archaea grow as plankton in the oceans. Symbiotic prokaryotes live in or on the bodies of other organisms, including humans. In 1977, Carl Woese proposed dividing prokaryotes into the Bacteria and Archaea (originally Eubacteria and Archaebacteria) because of the major differences in the structure and genetics between the two groups of organisms. Archaea were originally thought to be extremophiles, living only in inhospitable conditions such as extremes of temperature, pH, and radiation but have since been found in all types of habitats. The resulting arrangement of Eukaryota (also called "Eucarya"), Bacteria, and Archaea is called the three-domain system, replacing the traditional two-empire system | Biology | https://en.wikipedia.org/wiki?curid=19172225 | Prokaryote | 140,576 |
Prokaryote A widespread current model of the evolution of the first living organisms is that these were some form of prokaryotes, which may have evolved out of protocells, while the eukaryotes evolved later in the history of life. Some authors have questioned this conclusion, arguing that the current set of prokaryotic species may have evolved from more complex eukaryotic ancestors through a process of simplification. Others have argued that the three domains of life arose simultaneously, from a set of varied cells that formed a single gene pool. This controversy was summarized in 2005: There is no consensus among biologists concerning the position of the eukaryotes in the overall scheme of cell evolution. Current opinions on the origin and position of eukaryotes span a broad spectrum including the views that eukaryotes arose first in evolution and that prokaryotes descend from them, that eukaryotes arose contemporaneously with eubacteria and archaebacteria and hence represent a primary line of descent of equal age and rank as the prokaryotes, that eukaryotes arose through a symbiotic event entailing an endosymbiotic origin of the nucleus, that eukaryotes arose without endosymbiosis, and that eukaryotes arose through a symbiotic event entailing a simultaneous endosymbiotic origin of the flagellum and the nucleus, in addition to many other models, which have been reviewed and summarized elsewhere. The oldest known fossilized prokaryotes were laid down approximately 3 | Biology | https://en.wikipedia.org/wiki?curid=19172225 | Prokaryote | 140,577 |
Prokaryote 5 billion years ago, only about 1 billion years after the formation of the Earth's crust. Eukaryotes only appear in the fossil record later, and may have formed from endosymbiosis of multiple prokaryote ancestors. The oldest known fossil eukaryotes are about 1.7 billion years old. However, some genetic evidence suggests eukaryotes appeared as early as 3 billion years ago. While Earth is the only place in the universe where life is known to exist, some have suggested that there is evidence on Mars of fossil or living prokaryotes. However, this possibility remains the subject of considerable debate and skepticism. The division between prokaryotes and eukaryotes is usually considered the most important distinction or difference among organisms. The distinction is that eukaryotic cells have a "true" nucleus containing their DNA, whereas prokaryotic cells do not have a nucleus. Both eukaryotes and prokaryotes contain large RNA/protein structures called ribosomes, which produce protein, but the ribosomes of prokaryotes are smaller than those of eukaryotes. Mitochondria and chloroplasts, two organelles found in many eukaryotic cells, contain ribosomes similar in size and makeup to those found in prokaryotes. This is one of many pieces of evidence that mitochondria and chloroplasts are descended from free-living bacteria | Biology | https://en.wikipedia.org/wiki?curid=19172225 | Prokaryote | 140,578 |
Prokaryote The endosymbiotic theory holds that early eukaryotic cells took in primitive prokaryotic cells by phagocytosis and adapted themselves to incorporate their structures, leading to the mitochondria and chloroplasts. The genome in a prokaryote is held within a DNA/protein complex in the cytosol called the nucleoid, which lacks a nuclear envelope. The complex contains a single, cyclic, double-stranded molecule of stable chromosomal DNA, in contrast to the multiple linear, compact, highly organized chromosomes found in eukaryotic cells. In addition, many important genes of prokaryotes are stored in separate circular DNA structures called plasmids. Like Eukaryotes, prokaryotes may partially duplicate genetic material, and can have a haploid chromosomal composition that is partially replicated, a condition known as merodiploidy. Prokaryotes lack mitochondria and chloroplasts. Instead, processes such as oxidative phosphorylation and photosynthesis take place across the prokaryotic cell membrane. However, prokaryotes do possess some internal structures, such as prokaryotic cytoskeletons. It has been suggested that the bacterial order Planctomycetes have a membrane around their nucleoid and contain other membrane-bound cellular structures. However, further investigation revealed that Planctomycetes cells are not compartmentalized or nucleated and like the other bacterial membrane systems are all interconnected. Prokaryotic cells are usually much smaller than eukaryotic cells | Biology | https://en.wikipedia.org/wiki?curid=19172225 | Prokaryote | 140,579 |
Prokaryote Therefore, prokaryotes have a larger surface-area-to-volume ratio, giving them a higher metabolic rate, a higher growth rate, and as a consequence, a shorter generation time than eukaryotes. There is increasing evidence that the roots of the eukaryotes are to be found in (or at least next by) the archaean asgard group, perhaps Heimdallarchaeota (an idea which is a modern version of the 1984 eocyte hypothesis, "eocytes" being an old synonym for "crenarchaeota", a taxon to be found nearby the then unknown asgard group) For example, histones usually packaging DNA in eukarotic nuclei, have also been found in several archaean groups, giving evidence for homology. This idea might clarify the mysterious predecessor of eukaryotic cells (eucytes) which engulfed an alphaproteobacterium forming the first eucyte (LECA, last eukaryotic common ancestor) according to endosymbiotic theory. There might have been some additional support by viruses, called viral eukaryogenesis. The non-bacterial group comprising archaea and eukaryota has been called Neomura by Thomas Cavalier-Smith in 2002. However, in a cladistic view eukaryota "are" archaea in the same sense as birds "are" dinosaurs because they evolved from the maniraptora dinosaur group. In contrast, archaea "without" eukaryota appear to be a paraphyletic group, just like dinosaurs without birds | Biology | https://en.wikipedia.org/wiki?curid=19172225 | Prokaryote | 140,580 |
Prokaryote Unlike the above assumption of a fundamental split between prokaryotes and eukaryotes, the most important difference between biota may be the division between bacteria and the rest (archaea and eukaryota). For instance, DNA replication differs fundamentally between bacteria and archaea (including that in eukaryotic nuclei), and it may not be homologous between these two groups. Moreover, ATP synthase, though common (homologous) in all organisms, differs greatly between bacteria (including eukaryotic organelles such as mitochondria and chloroplasts) and the archaea/eukaryote nucleus group. The last common antecessor of all life (called LUCA, last universal common ancestor) should have possessed an early version of this protein complex. As ATP synthase is obligate membrane bound, this supports the assumption that LUCA was a cellular organism. The RNA world hypothesis might clarify this scenario, as LUCA might have been a ribocyte (also called ribocell) lacking DNA, but with an RNA genome built by ribosomes as primordial self-replicating entities. A Peptide-RNA world (also called RNP world) hypothesis has been proposed based on the idea that oligopeptides may have been built together with primordial nucleic acids at the same time, which also supports the concept of a ribocyte as LUCA | Biology | https://en.wikipedia.org/wiki?curid=19172225 | Prokaryote | 140,581 |
Prokaryote The feature of DNA as the material base of the genome might have then been adopted separately in bacteria and in archaea (and later eukaryote nuclei), presumably by help of some viruses (possibly retroviruses as they could reverse transcribe RNA to DNA). As a result, prokaryota comprising bacteria and archaea may also be polyphyletic. | Biology | https://en.wikipedia.org/wiki?curid=19172225 | Prokaryote | 140,582 |
Mueller-Hinton agar is a microbiological growth medium that is commonly used for antibiotic susceptibility testing. It is also used to isolate and maintain "Neisseria" and "Moraxella" species. It typically contains: Five percent sheep blood and nicotinamide adenine dinucleotide may also be added when susceptibility testing is done on "Streptococcus" species. This type is also commonly used for susceptibility testing of "Campylobacter". It has a few properties that make it excellent for antibiotic use. First of all, it is a nonselective, nondifferential medium. This means that almost all organisms plated on it will grow. Additionally, it contains starch. Starch is known to absorb toxins released from bacteria, so that they cannot interfere with the antibiotics. Second, it is a loose agar. This allows for better diffusion of the antibiotics than most other plates. A better diffusion leads to a truer zone of inhibition. was co-developed by microbiologist John Howard Mueller and veterinary scientist Jane Hinton at Harvard university as a culture for gonococcus and meningococcus, who published the method in 1941. | Biology | https://en.wikipedia.org/wiki?curid=19174753 | Mueller-Hinton agar | 140,583 |
Protocell A protocell (or protobiont) is a self-organized, endogenously ordered, spherical collection of lipids proposed as a stepping-stone toward the origin of life. A central question in evolution is how simple protocells first arose and how they could differ in reproductive output, thus enabling the accumulation of novel biological emergences over time, i.e. biological evolution. Although a functional protocell has not yet been achieved in a laboratory setting, the goal to understand the process appears well within reach. Compartmentalization was important in the origins of life. Membranes form enclosed compartments that are separate from the external environment, thus providing the cell with functionally specialized aqueous spaces. As the lipid bilayer of membranes is impermeable to most hydrophilic molecules (dissolved by water), cells have membrane transport-systems that achieve the import of nutritive molecules as well as the export of waste. It is very challenging to construct protocells from molecular assemblies. An important step in this challenge is the achievement of vesicle dynamics that are relevant to cellular functions, such as membrane trafficking and self-reproduction, using amphiphilic molecules. On the primitive Earth, numerous chemical reactions of organic compounds produced the ingredients of life. Of these substances, amphiphilic molecules might be the first player in the evolution from molecular assembly to cellular life | Biology | https://en.wikipedia.org/wiki?curid=19179678 | Protocell | 140,584 |
Protocell A step from vesicle toward protocell might be to develop self-reproducing vesicles coupled with the metabolic system. Self-assembled vesicles are essential components of primitive cells. The second law of thermodynamics requires that the universe move in a direction in which disorder (or entropy) increases, yet life is distinguished by its great degree of organization. Therefore, a boundary is needed to separate life processes from non-living matter. The cell membrane is the only cellular structure that is found in all of the cells of all of the organisms on Earth. Researchers Irene A. Chen and Jack W. Szostak (Nobel Prize in Physiology or Medicine 2009) amongst others, demonstrated that simple physicochemical properties of elementary protocells can give rise to simpler conceptual analogues of essential cellular behaviors, including primitive forms of Darwinian competition and energy storage. Such cooperative interactions between the membrane and encapsulated contents could greatly simplify the transition from replicating molecules to true cells. Competition for membrane molecules would favor stabilized membranes, suggesting a selective advantage for the evolution of cross-linked fatty acids and even the phospholipids of today. This micro-encapsulation allowed for metabolism within the membrane, exchange of small molecules and prevention of passage of large substances across it. The main advantages of encapsulation include increased solubility of the cargo and creating energy in the form of chemical gradient | Biology | https://en.wikipedia.org/wiki?curid=19179678 | Protocell | 140,585 |
Protocell Energy is thus often said to be stored by cells in the structures of molecules of substances such as carbohydrates (including sugars), lipids, and proteins, which release energy when chemically combined with oxygen during cellular respiration. A March 2014 study by NASA's Jet Propulsion Laboratory demonstrated a unique way to study the origins of life: fuel cells. Fuel cells are similar to biological cells in that electrons are also transferred to and from molecules. In both cases, this results in electricity and power. The study states that one important factor was that the Earth provides electrical energy at the seafloor. "This energy could have kick-started life and could have sustained life after it arose. Now, we have a way of testing different materials and environments that could have helped life arise not just on Earth, but possibly on Mars, Europa and other places in the Solar System." When phospholipids are placed in water, the molecules spontaneously arrange such that the tails are shielded from the water, resulting in the formation of membrane structures such as bilayers, vesicles, and micelles. In modern cells, vesicles are involved in metabolism, transport, buoyancy control, and enzyme storage. They can also act as natural chemical reaction chambers. A typical vesicle or micelle in aqueous solution forms an aggregate with the hydrophilic "head" regions in contact with surrounding solvent, sequestering the hydrophobic single-tail regions in the micelle centre | Biology | https://en.wikipedia.org/wiki?curid=19179678 | Protocell | 140,586 |
Protocell This phase is caused by the packing behavior of single-tail lipids in a bilayer. Although the protocellular self-assembly process that spontaneously form lipid "monolayer" vesicles and micelles in nature resemble the kinds of primordial vesicles or protocells that might have existed at the beginning of evolution, they are not as sophisticated as the "bilayer" membranes of today's living organisms. Rather than being made up of phospholipids, however, early membranes may have formed from monolayers or bilayers of fatty acids, which may have formed more readily in a prebiotic environment. Fatty acids have been synthesized in laboratories under a variety of prebiotic conditions and have been found on meteorites, suggesting their natural synthesis in nature. Oleic acid vesicles represent good models of membrane protocells that could have existed in prebiotic times. Electrostatic interactions induced by short, positively charged, hydrophobic peptides containing 7 amino acids in length or fewer, can attach RNA to a vesicle membrane, the basic cell membrane. Scientists have suggested that life began in hydrothermal vents in the deep sea, but a 2012 study suggests that inland pools of condensed and cooled geothermal vapor have the ideal characteristics for the origin of life. The conclusion is based mainly on the chemistry of modern cells, where the cytoplasm is rich in potassium, zinc, manganese, and phosphate ions, which are not widespread in marine environments | Biology | https://en.wikipedia.org/wiki?curid=19179678 | Protocell | 140,587 |
Protocell Such conditions, the researchers argue, are found only where hot hydrothermal fluid brings the ions to the surface—places such as geysers, mud pots, fumaroles and other geothermal features. Within these fuming and bubbling basins, water laden with zinc and manganese ions could have collected, cooled and condensed in shallow pools. Another study in the 1990s showed that montmorillonite clay can help create RNA chains of as many as 50 nucleotides joined together spontaneously into a single RNA molecule. Later, in 2002, it was discovered that by adding montmorillonite to a solution of fatty acid micelles (lipid spheres), the clay sped up the rate of vesicle formation 100-fold. Research has shown that some minerals can catalyze the stepwise formation of hydrocarbon tails of fatty acids from hydrogen and carbon monoxide gases—gases that may have been released from hydrothermal vents or geysers. Fatty acids of various lengths are eventually released into the surrounding water, but vesicle formation requires a higher concentration of fatty acids, so it is suggested that protocell formation started at land-bound hydrothermal vents such as geysers, mud pots, fumaroles and other geothermal features where water evaporates and concentrates the solute. Another group suggests that primitive cells might have formed inside inorganic clay microcompartments, which can provide an ideal container for the synthesis and compartmentalization of complex organic molecules | Biology | https://en.wikipedia.org/wiki?curid=19179678 | Protocell | 140,588 |
Protocell Clay-armored "bubbles" form naturally when particles of montmorillonite clay collect on the outer surface of air bubbles under water. This creates a semi permeable vesicle from materials that are readily available in the environment. The authors remark that montmorillonite is known to serve as a chemical catalyst, encouraging lipids to form membranes and single nucleotides to join into strands of RNA. Primitive reproduction can be envisioned when the clay bubbles burst, releasing the lipid membrane-bound product into the surrounding medium. Another way to form primitive compartments that may lead to the formation of a protocell is polyesters membraneless structures that have the ability to host biochemicals (proteins and RNA) and/or scaffold the assemblies of lipids around them. While these droplets are leaky towards genetic materials, this leakiness could have facilitated the progenote hypothesis. For cellular organisms, the transport of specific molecules across compartmentalizing membrane barriers is essential in order to exchange content with their environment and with other individuals. For example, content exchange between individuals enables horizontal gene transfer, an important factor in the evolution of cellular life. While modern cells can rely on complicated protein machineries to catalyze these crucial processes, protocells must have accomplished this using more simple mechanisms | Biology | https://en.wikipedia.org/wiki?curid=19179678 | Protocell | 140,589 |
Protocell Protocells composed of fatty acids would have been able to easily exchange small molecules and ions with their environment. Membranes consisting of fatty acids have a relatively high permeability to molecules such as nucleoside monophosphate (NMP), nucleoside diphosphate (NDP), and nucleoside triphosphate (NTP), and may withstand millimolar concentrations of Mg. Osmotic pressure can also play a significant role regarding this passive membrane transport. Environmental effects have been suggested to trigger conditions under which a transport of larger molecules, such as DNA and RNA, across the membranes of protocells is possible. For example, it has been proposed that electroporation resulting from lightning strikes could enable such transport. Electroporation is the rapid increase in bilayer permeability induced by the application of a large artificial electric field across the membrane. During electroporation, the lipid molecules in the membrane shift position, opening up a pore (hole) that acts as a conductive pathway through which hydrophobic molecules like nucleic acids can pass the lipid bilayer. A similar transfer of content across protocells and with the surrounding solution can be caused by freezing and subsequent thawing. This could, for instance, occur in an environment in which day and night cycles cause recurrent freezing. Laboratory experiments have shown that such conditions allow an exchange of genetic information between populations of protocells | Biology | https://en.wikipedia.org/wiki?curid=19179678 | Protocell | 140,590 |
Protocell This can be explained by the fact that membranes are highly permeable at temperatures slightly below their phase transition temperature. If this point is reached during the freeze-thaw cycle, even large and highly charged molecules can temporarily pass the protocell membrane. Some molecules or particles are too large or too hydrophilic to pass through a lipid bilayer even under these conditions, but can be moved across the membrane through fusion or budding of vesicles, events which have also been observed for freeze-thaw cycles. This may eventually have led to mechanisms that facilitate movement of molecules to the inside of the protocell (endocytosis) or to release its contents into the extracellular space (exocytosis). Starting with a technique commonly used to deposit molecules on a solid surface, Langmuir–Blodgett deposition, scientists are able to assemble phospholipid membranes of arbitrary complexity layer by layer. These artificial phospholipid membranes support functional insertion both of purified and of "in situ" expressed membrane proteins. The technique could help astrobiologists understand how the first living cells originated. Jeewanu protocells are synthetic chemical particles that possess cell-like structure and seem to have some functional living properties | Biology | https://en.wikipedia.org/wiki?curid=19179678 | Protocell | 140,591 |
Protocell First synthesized in 1963 from simple minerals and basic organics while exposed to sunlight, it is still reported to have some metabolic capabilities, the presence of semipermeable membrane, amino acids, phospholipids, carbohydrates and RNA-like molecules. However, the nature and properties of the Jeewanu remains to be clarified. In a similar synthesis experiment a frozen mixture of water, methanol, ammonia and carbon monoxide was exposed to ultraviolet (UV) radiation. This combination yielded large amounts of organic material that self-organised to form globules or vesicles when immersed in water. The investigating scientist considered these globules to resemble cell membranes that enclose and concentrate the chemistry of life, separating their interior from the outside world. The globules were between , or about the size of red blood cells. Remarkably, the globules fluoresced, or glowed, when exposed to UV light. Absorbing UV and converting it into visible light in this way was considered one possible way of providing energy to a primitive cell. If such globules played a role in the origin of life, the fluorescence could have been a precursor to primitive photosynthesis. Such fluorescence also provides the benefit of acting as a sunscreen, diffusing any damage that otherwise would be inflicted by UV radiation | Biology | https://en.wikipedia.org/wiki?curid=19179678 | Protocell | 140,592 |
Protocell Such a protective function would have been vital for life on the early Earth, since the ozone layer, which blocks out the sun's most destructive UV rays, did not form until after photosynthetic life began to produce oxygen. The synthesis of three kinds of "jeewanu" have been reported; two of them were organic, and the other was inorganic. Other similar inorganic structures have also been produced. The investigating scientist (V. O. Kalinenko) referred to them as "bio-like structures" and "artificial cells". Formed in distilled water (as well as on agar gel) under the influence of an electric field, they lack protein, amino acids, purine or pyrimidine bases, and certain enzyme activities. According to NASA researchers, "presently known scientific principles of biology and biochemistry cannot account for living inorganic units" and "the postulated existence of these living units has not been proved". research has created controversy and opposing opinions, including critics of the vague definition of "artificial life". The creation of a basic unit of life is the most pressing ethical concern, although the most widespread worry about protocells is their potential threat to human health and the environment through uncontrolled replication. | Biology | https://en.wikipedia.org/wiki?curid=19179678 | Protocell | 140,593 |
Recognition memory Recognition memory, a subcategory of declarative memory, is the ability to recognize previously encountered events, objects, or people. When the previously experienced event is reexperienced, this environmental content is matched to stored memory representations, eliciting matching signals. As first established by psychology experiments in the 1970s, recognition memory for pictures is quite remarkable: humans can remember thousands of images at high accuracy after seeing each only once and only for a few seconds. can be subdivided into two component processes: recollection and familiarity, sometimes referred to as "remembering" and "knowing", respectively. Recollection is the retrieval of details associated with the previously experienced event. In contrast, familiarity is the feeling that the event was previously experienced, without recollection. Thus, the fundamental distinction between the two processes is that recollection is a slow, controlled search process, whereas familiarity is a fast, automatic process. Mandler's "Butcher-on-the-bus" example: Imagine taking a seat on a crowded bus. You look to your left and notice a man. Immediately, you are overcome with this sense that you've seen this man before, but you cannot remember who he is. This automatically elicited feeling is familiarity. While trying to remember who this man is, you begin retrieving specific details about your previous encounter. For example, you might remember that this man handed you a fine chop of meat in the grocery store | Biology | https://en.wikipedia.org/wiki?curid=21312318 | Recognition memory | 140,594 |
Recognition memory Or perhaps you remember him wearing an apron. This search process is recollection. The phenomenon of familiarity and recognition has long been described in books and poems. Within the field of Psychology, recognition memory was first alluded to by Wilhelm Wundt in his concept of "know-againness" or "assimilation" of a former memory image to a new one. The first formal attempt to describe recognition was by the English Doctor Arthur Wigan in his book "Duality of the Mind". Here he describes the feelings of familiarity we experience as being due to the brain being a double organ. In essence we perceive things with one half of our brain and if they somehow get lost in translation to the other side of the brain this causes the feeling of recognition when we again see said object, person etc. However, he incorrectly assumed that these feelings occur only when the mind is exhausted (from hunger, lack of sleep etc.). His description, though elementary compared to current knowledge, set the groundwork and sparked interest in this topic for subsequent researchers. Arthur Allin (1896) was the first person to publish an article attempting to explicitly define and differentiate between subjective and objective definitions of the experience of recognition although his findings are based mostly on introspections. Allin corrects Wigan's notion of the exhausted mind by asserting that this half-dream state is not the process of recognition | Biology | https://en.wikipedia.org/wiki?curid=21312318 | Recognition memory | 140,595 |
Recognition memory He rather briefly refers to the physiological correlates of this mechanism as having to do with the cortex but does not go into detail as to where these substrates are located. His objective explanation of the lack of recognition is when a person observes an object for a second time and experiences the feeling of familiarity that they experienced this object at a previous time. Woodsworth (1913) and Margaret and Edward Strong (1916) were the first people to experimentally use and record findings employing the delayed matching to sample task to analyze recognition memory. Following this Benton Underwood was the first person to analyze the concept of recognition errors in relation to words in 1969. He deciphered that these recognition errors occur when words have similar attributes. Next came attempts to determine the upper limits of recognition memory, a task that Standing (1973) endeavored. He determined that the capacity for pictures is almost limitless. In 1980 George Mandler introduced the recollection-familiarity distinction, more formally known as the dual process theory It is debatable whether familiarity and recollection should be considered as separate categories of recognition memory. This familiarity-recollection distinction is what is called a "dual-process model/theory" | Biology | https://en.wikipedia.org/wiki?curid=21312318 | Recognition memory | 140,596 |
Recognition memory "Despite the popularity and influence of dual-process theories [for recognition memory], they are controversial because of the difficulty in obtaining separate empirical estimates of recollection and familiarity and the greater parsimony associated with single-process theories." A common criticism of dual process models of recognition is that recollection is simply a stronger (i.e. more detailed or vivid) version of familiarity. Thus, rather than consisting of two separate categories, single-process models regard recognition memory as a continuum ranging from weak memories to strong memories. An account of the history of dual process models since the late 1960s also includes techniques for the measurement of the two processes. Evidence for the single-process view comes from an electrode recording study done on epileptic patients who took an item-recognition task. This study found that hippocampal neurons, regardless of successful recollection, responded to the familiarity of objects. Thus, the hippocampus may not exclusively subserve the recollection process. However, they also found that successful item recognition was not related to whether or not 'familiarity' neurons fired. Therefore, it's not entirely clear which responses relate to successful item recognition. However, one study suggested that hippocampal activation does not necessarily mean that conscious recollection will occur | Biology | https://en.wikipedia.org/wiki?curid=21312318 | Recognition memory | 140,597 |
Recognition memory In this object-scene associative recognition study, hippocampal activation was not related to successful associative recollection; it was only when the prefrontal cortex and the hippocampus was activated that successful performance was observed. Further, eye tracking evidence revealed that participants looked longer at the correct stimulus, and this was related to increases in hippocampal activity. Therefore, the hippocampus may play a role in the recovery of relational information, but it requires concomitant activation with the prefrontal cortex for conscious recollection. Studies with amnesics, do not seem to support the single-process notion. A number of reports feature patients with selective damage to the hippocampus who are impaired only in recollection but not in familiarity, which provides tentative support for dual-process models. Further, a double dissociation between recollection and familiarity has been observed. Patient N.B. had regions of her medial temporal lobes removed, including the perirhinal cortex and entorhinal cortex, but her hippocampus and parahippocampal cortex were spared. She exhibited impaired familiarity but intact recollection processes relative to controls in a yes-no recognition paradigm, and this was elucidated using ROC, RK, and response-deadline procedures. In another study, even when performance between patient N.B. was matched to one amnesic patient who had their hippocampus removed, the double dissociation was still present | Biology | https://en.wikipedia.org/wiki?curid=21312318 | Recognition memory | 140,598 |
Recognition memory While performance was matched post hoc and replication is needed, this evidence rules out the idea that these brain regions are part of a unitary memory strength system. Instead, this double dissociation strongly suggests that distinct brain regions and systems underlie both recollection and familiarity processes. The dual process theories make it possible to distinguish two types of recognition: first, recognizing THAT one has encountered some object/event before; and second recognizing WHAT that object/event was. Thus one may recognize a face, but only later recollect whose face it was. Delayed recognition also shows differences between fast familiarity and slow recollection processes In addition, in the “familiarity” system of recognizing memory two functional subsystems are distinguished: the first one is responsible for recognition of previously presented stimuli and the second one supports recognition of objects as new. At present, neuroscientific research has not provided a definitive answer to this controversy, although it heavily favors dual-process models. While many studies provide evidence that recollection and familiarity are represented in separate regions of the brain, other studies show that this is not always the case; there may be a great deal of neuroanatomical overlap between the two processes. Despite the fact that familiarity and recollection sometimes activate the same brain regions, they are typically quite distinct functionally | Biology | https://en.wikipedia.org/wiki?curid=21312318 | Recognition memory | 140,599 |
Recognition memory The question of whether recollection and familiarity exist as two independent categories or along a continuum may ultimately be irrelevant; the bottom line is that the recollection-familiarity distinction has been extremely useful in understanding how recognition memory works. Used to assess recognition memory based on the pattern of yes-no responses. This is one of the simplest forms of testing for recognition, and is done so by giving a participant an item and having them indicate 'yes' if it is old or 'no' if it is a new item. This method of recognition testing makes the retrieval process easy to record and analyze. Participants are asked to identify which of several items (two to four) is correct. One of the presented items is the target—a previously presented item. The other items are similar, and act as distractors. This allows the experimenter a degree of manipulation and control in item similarity or item resemblance. This helps provide a better understanding of retrieval, and what kinds of existing knowledge people use to decide based on memory. When response time is recorded (in milliseconds or seconds), a faster speed is thought to reflect a simpler process, whereas slower times reflect more complex physiological processes. Hermann von Helmholtz was the first psychologist to inquire whether the velocity of a nerve impulse could be a speed that is measurable. He devised an experimental set-up for measuring psychological processes with a very precise and critical time-scale | Biology | https://en.wikipedia.org/wiki?curid=21312318 | Recognition memory | 140,600 |
Recognition memory The birth of mental chronometry is attributed to an experiment by Helmholtz's colleague, Franciscus Donders. In the experiment, he attached electrodes to both feet of the subject. He then administered a mild shock to either the left or right foot, and told the subject to move the hand on the same side—which turned the stimulus (the shock) off. In a different condition, the subject was not told which foot the stimulus would act on. The time difference between these conditions was measured as one-fifteenth of a second. This was a significant finding in early experimental psychology, because researchers previously thought that psychological processes were too fast to measure. An early model of dual process theories was suggested by Atkinson and Juola's (1973) model. In this theory, the familiarity process would be the first activated as a fast search for recognition. If that is unsuccessful in retrieving the memory trace, then there is a more forced search into the long-term memory store. The "horse-race" model is a more recent view of dual process theories. This view suggests that the two processes of familiarity and recollection occur simultaneously, but that familiarity, being the faster process, completes the search before recollection. This view holds true the idea that familiarity is an unconscious process whereas recollection is more conscious, thoughtful. In circumstances of uncertainty, identification of a prior occurrence depends on decision-making processes | Biology | https://en.wikipedia.org/wiki?curid=21312318 | Recognition memory | 140,601 |
Recognition memory The available information must be compared with some internal criteria that provide guidance on which decision is more advantageous. Signal detection theory has been applied to recognition memory as a method of estimating the effect of the application of these internal criteria, referred to as bias. Critical to the dual process model is the assumption that recognition memory reflects a signal detection process in which old and new items each have a distinct distribution along a dimension, such as familiarity. The application of Signal Detection Theory (SDT) to memory depends on conceiving of a memory trace as a signal that the subject must detect in order to perform in a retention task. Given this conception of memory performance, it is reasonable to assume that percentage correct scores may be biased indicators of retention—just as thresholds may be biased indicators of sensory performance—and, in addition, that SDT techniques should be used where possible to separate the truly retention-based aspects of memory performance from the decision aspects. In particular, we assume that the subject compares the trace strength of the test item with a criterion, responding "yes" if the strength exceeds the criterion and "no"otherwise. There are two types of test items, "old" (a test item that appeared in the list for that trial) and new" (one that did not appear in the list). Strength theory assumes that there may be noise in the value of the trace strength, the location of the criterion, or both | Biology | https://en.wikipedia.org/wiki?curid=21312318 | Recognition memory | 140,602 |
Recognition memory We assume that this noise is normally distributed. The reporting criterion can shift along the continuum in the direction of more false hits, or more misses. The momentary memory strength of a test item is compared with the decision criteria and if the strength of the item falls within the judgment category, Jt, defined by the placement of the criteria, S makes judgment. The strength of an item is assumed to decline monotonically (with some error variance) as a continuous function of time or number of intervening items. False hits are 'new' words incorrectly recognized as old, and a greater proportion of these represents a liberal bias. Misses are 'old' words mistakenly not recognized as old, and a greater proportion of these represents a conservative bias. The relative distributions of false hits and misses can be used to interpret recognition task performance and correct for guessing. Only target items can generate an above-threshold recognition response because only they appeared on the list. The lures, along with any targets that are forgotten, fall below threshold, which means that they generate no memory signal whatsoever. False alarms in this model reflect memory-free guesses that are made to some of the lures. The level of cognitive processing performed on a given stimuli has an effect on recognition memory performance, with more elaborate, associative processing resulting in better memory performance | Biology | https://en.wikipedia.org/wiki?curid=21312318 | Recognition memory | 140,603 |
Recognition memory For example, recognition performance is improved through the use of semantic associations over feature associations. However, this process is mediated by other features of the stimuli, for example, the relatedness of the items to one another. If the items are highly interrelated, lower-depth item-specific processing (such as rating the pleasantness of each item) helps to distinguish them from one another, and improves recognition memory performance over relational processing. This unusual phenomenon is explained by the automatic tendency to perform relational processing on highly interrelated items. Recognition performance is improved by additional processing, even of a lower level of associativeness, but not by a task that duplicates the automated processing already performed on the list of items. There are a variety of ways that context can influence memory. Encoding specificity describes how memory performance is enhanced if testing conditions match learning (encoding) conditions. Certain aspects during the learning period, whether it be the environment, your current physical state, or even your mood, become encoded in the memory trace. Later during retrieval, any of these aspects can serve as cues to aid in recognition. For example, research by Godden and Baddeley tested this concept on scuba divers. Some groups learned their scuba lessons on land, and others learned in the water. Likewise, some groups were tested for their knowledge on land, and others in the water | Biology | https://en.wikipedia.org/wiki?curid=21312318 | Recognition memory | 140,604 |
Recognition memory Not surprisingly, test results were highest when retrieval conditions matched encoding conditions (those who learned on land performed best on land, and vice versa for water). There have also been studies that show similar effects regarding an individual's physical state. This is known as state-dependent learning. Another type of encoding specificity is mood congruent memory, where individuals are more likely to remember material if the emotional content of the material and the prevailing mood at recall matched. The presence of other individuals can also have an effect on recognition. Two opposing effects, collaborative inhibition and collaborative facilitation impact memory performance in groups. Specifically, collaborative facilitation refers to the increased performance on recognition tasks in groups. The opposite, collaborative inhibition, refers to a decreased memory performance on recall tasks in groups. This is because in a recall task, a specific memory trace must be activated, and outside ideas could produce a kind of interference. Recognition, on the other hand does not utilize the same manner of retrieval plan as recall and is therefore not affected. The two basic categories of recognition memory errors are false hits (or false alarms) and misses. A false hit is the identification of an occurrence as old when it is in fact new. A miss is the failure to identify a previous occurrence as old. Two specific types of false hits emerge when elicited through the use of a recognition lure | Biology | https://en.wikipedia.org/wiki?curid=21312318 | Recognition memory | 140,605 |
Recognition memory The first is a feature error, in which a part of an old stimulus is presented in combination with a new element. For example, if the original list contained "blackbird, jailbait, buckwheat", a feature error may be elicited through the presentation of "buckshot" or "blackmail" at test, as each of these lures has an old and a new component. The second type of error is a conjunction error, in which parts of multiple old stimuli are combined. Using the same example, "jailbird" could elicit a conjunction error, as it is a conjunction of two old stimuli. Both types of errors can be elicited through both auditory and visual modalities, suggesting that the processes that produce these errors are not modality-specific. A third false hit error can be induced through the use of the Deese–Roediger–McDermott paradigm. If all items studied are highly related to one word that does not appear on the list, the subject is highly likely to recognize that word as old in the test. An example of this would be a list containing the following words: nap, drowsy, bed, duvet, night, relax. The lure in this case is the word 'sleep'. It is highly likely that 'sleep' would be falsely recognized as appearing on that list due to the level of activation received from the list words. This phenomenon is so pervasive that the rate of false generated in this manner can even surpass the rate of correct responses According to Robert L | Biology | https://en.wikipedia.org/wiki?curid=21312318 | Recognition memory | 140,606 |
Recognition memory Green (1996), the mirror effect occurs when stimuli that are easy to recognize as old when old are also easy to recognize as new when new in recognition. The mirror effect refers to the consistency of the recognition of the stimuli in memory. In other words, they are easier to remember when you have previously studied the stimuli i.e., old, and easier to reject when you have not seen them before, i.e. new. Murray Glanzer and John K. Adams first described the mirror effect in 1985. The mirror effect has been effective in tests of associative recognition, measures of latency responses, discriminations of order, and others (Glanzer & Adams, 1985). On the whole, research concerning the neural substrates of familiarity and recollection demonstrates that these processes typically involve different brain regions, thereby supporting a dual-process theory of recognition memory. However, due to the complexity and inherent interconnectivity of the neural networks of the brain, and given the close proximity of regions involved in familiarity to regions involved in recollection, it is difficult to pinpoint the structures that are specifically related to recollection or to familiarity. What is known at present is that most of a number of neuroanatomical regions involved in recognition memory are primarily associated with one subcomponent over the other | Biology | https://en.wikipedia.org/wiki?curid=21312318 | Recognition memory | 140,607 |
Recognition memory is critically dependent on a hierarchically organized network of brain areas including the visual ventral stream, medial temporal lobe structures, frontal lobe and parietal cortices along with the hippocampus. As mentioned previously, the processes of recollection and familiarity are represented differently in the brain. As such, each of the regions listed above can be further subdivided according to which part is primarily involved in recollection or in familiarity. In the temporal cortex, for instance, the medial region is related to recollection whereas the anterior region is related to familiarity. Similarly, in the parietal cortex, the lateral region is related to recollection whereas the superior region is related to familiarity. An even more specific account divides the medial parietal region, relating the posterior cingulate to recollection and the precuneus to familiarity. The hippocampus plays a prominent role in recollection whereas familiarity depends heavily on the surrounding medial-temporal regions, especially the perirhinal cortex. Finally, it is not yet clear what specific regions of the prefrontal lobes are associated with recollection versus familiarity, although there is evidence that the left prefrontal cortex is correlated more strongly with recollection whereas the right prefrontal cortex is involved more in familiarity | Biology | https://en.wikipedia.org/wiki?curid=21312318 | Recognition memory | 140,608 |
Recognition memory Though left-side activation involved in recollection was originally hypothesized to result from semantic processing of words (many of these earlier studies used written words for stimuli) subsequent studies using nonverbal stimuli produced the same finding—suggesting that prefrontal activation in the left hemisphere results from any kind of detailed remembering. As previously mentioned, recognition memory is not a stand-alone concept; rather it is a highly interconnected and integrated sub-system of memory. Perhaps misleadingly, the regions of the brain listed above correspond to an abstract and highly generalized understanding of recognition memory, in which the stimuli or items-to-be-recognized are not specified. In reality, however, the location of brain activation involved in recognition is highly dependent on the nature of the stimulus itself. Consider the conceptual differences in recognizing written words compared to recognizing human faces. These are two qualitatively different tasks and as such it is not surprising that they involve additional, distinct regions of the brain. Recognizing words, for example, involves the visual word form area, a region in the left fusiform gyrus, which is believed to specialized in recognizing written words. Similarly, the fusiform face area, located in the right hemisphere, is linked specifically to the recognition of faces. Strictly speaking, recognition is a process of memory "retrieval". But how a memory is formed in the first place affects how it is retrieved | Biology | https://en.wikipedia.org/wiki?curid=21312318 | Recognition memory | 140,609 |
Recognition memory An interesting area of study related to recognition memory deals with how memories are initially learned or encoded in the brain. This encoding process is an important aspect of recognition memory because it determines not only whether or not a previously introduced item is recognized, but "how" that item is retrieved through memory. Depending on the strength of the memory, the item may either be 'remembered' (i.e. a recollection judgment) or simply 'known' (i.e. a familiarity judgment). Of course, the strength of the memory depends on many factors, including whether or not the person was giving their full attention to memorizing the information or whether they were distracted, whether they are actively attempting to learn (intentional learning) or only learning passively, whether they were allowed to rehearse the information or not, etc., although these contextual details are beyond the scope of this entry. Several studies have shown that when an individual is devoting his/her full attention to the memorization process, the strength of the successful memory is related to the magnitude of bilateral activation in the prefrontal cortex, hippocampus, and parahippocampal gyrus. The greater the activation in these areas during learning, the better the memory. Thus, these areas are involved in the formation of detailed, recollective memories. In contrast, when subjects are distracted during the memory-encoding process, only the right prefrontal cortex and left parahippocampal gyrus are activated | Biology | https://en.wikipedia.org/wiki?curid=21312318 | Recognition memory | 140,610 |
Recognition memory These regions are associated with "a sense of knowing" or familiarity. Given that the areas involved in familiarity are also involved in recollection, this conforms to a single-process theory of recognition, at least insofar as the encoding of memories is concerned. is not confined to the visual domain; we can recognize things in each of the five traditional sensory modalities (i.e. sight, hearing, touch, smell, and taste). Although most neuroscientific research has focused on visual recognition, there have also been studies related to audition (hearing), olfaction (smell), gustation (taste), and tactition (touch). Auditory recognition memory is primarily dependent on the medial temporal lobe as displayed by studies on lesioned patients and amnesics. Moreover, studies conducted on monkeys and dogs have confirmed that perinhinal and entorhinal cortex lesions fail to affect auditory recognition memory as they do in vision. Further research needs must be done on the role of the hippocampus in auditory recognition memory, as studies in lesioned patients suggest that the hippocampus does play a small role in auditory recognition memory while studies with lesioned dogs directly conflict this finding. It has also been proposed that area TH is vital for auditory recognition memory but further research must be done in this area as well. Studies comparing visual and auditory recognition memory conclude the auditory modality is inferior | Biology | https://en.wikipedia.org/wiki?curid=21312318 | Recognition memory | 140,611 |
Recognition memory Research on human olfaction is scant in comparison to other senses such as vision and hearing, and studies specifically devoted to olfactory recognition are even rarer. Thus, what little information there is on this subject is gleaned through animal studies. Rodents such as mice or rats are suitable subjects for odor recognition research given that smell is their primary sense. "[For these species], recognition of individual body odors is analogous to human face recognition in that it provides information about identity." In mice, individual body odors are represented at the major histocompatibility complex (MHC). In a study performed with rats, the orbitofrontal cortex (OF) was found to play an important role in odor recognition. The OF is reciprocally connected with the perirhinal and entorhinal areas of the medial temporal lobe, which have also been implicated in recognition memory. Gustatory recognition memory, or the recognition of taste, is correlated with activity in the anterior temporal lobe (ATL). In addition to brain imaging techniques, the role of the ATL in gustatory recognition is evidenced by the fact that lesions to this area result in an increased threshold for taste recognition for humans. Cholinergic neurotransmission in the perirhinal cortex is essential for the acquisition of taste recognition memory and conditioned taste aversion in humans. Monkeys with lesions in the perirhinal and parahippocampal cortices also show impairment on tactual recognition | Biology | https://en.wikipedia.org/wiki?curid=21312318 | Recognition memory | 140,612 |
Recognition memory The concept of domain specificity is one that has helped researchers probe deeper into the neural substrates of recognition memory. Domain specificity is the notion that some areas of the brain are responsible almost exclusively for the processing of particular categories. For example, it is well documented that the fusiform gyrus (FFA) in the inferior temporal lobe is heavily involved in face recognition. A specific region in this gyrus is even named the fusiform face area due to its heightened neurological activity during face perception. Similarly there is also a region of the brain known as the parahippocampal place area on the parahippocampal gyrus. As the name implies, this area is sensitive to environmental context, places. Damage to these areas of the brain can lead to very specific deficits. For example, damage to the FFA often leads to prosopagnosia, an inability to recognize faces. Lesions to various brain regions such as these serve as case study data that help researchers understand the neural correlates of recognition. The medial temporal lobes and their surrounding structures are of immense importance to memory in general. The hippocampus is of particular interest. It has been well documented that damage here can result in severe retrograde or anterograde amnesia, the patient is unable to recollect certain events from their past or create new memories respectively. However, the hippocampus does not seem to be the "storehouse" of memory. Rather, it may function more as a relay station | Biology | https://en.wikipedia.org/wiki?curid=21312318 | Recognition memory | 140,613 |
Recognition memory Research suggests that it is through the hippocampus that short term memory engages in the process of consolidation (the transfer to long term storage). The memories are transferred from the hippocampus to the broader lateral neocortex via the entorhinal cortex. This helps explain why many amnesics have spared cognitive abilities. They may have a normal short term memory, but are unable to consolidate that memory and it is lost rapidly. Lesions in the medial temporal lobe often leave the subject with the capacity to learn new skills, also known as procedural memory. If experiencing anterograde amnesia, the subject cannot recall any of the learning trials, yet consistently improves with each trial. This highlights the distinctiveness of recognition as a particular and separate type of memory, falling into the domain of declarative memory. The hippocampus is also useful in the familiarity vs. recollection distinction in recognition as mentioned above. A familiar memory is a context free memory in which the person has a feeling of "know", as in, "I know I put my car keys here somewhere". It can sometimes be likened to a tip of the tongue feeling. Recollection on the other hand is a much more specific, deliberate, and conscious process, also termed remembering | Biology | https://en.wikipedia.org/wiki?curid=21312318 | Recognition memory | 140,614 |
Recognition memory The hippocampus is believed heavily involved in recollection, whereas familiarity is attributed to the perirhinal cortex and broader temporal cortex in general, however, there is debate over the validity of these neural substrates and even the familiarity/recollection separation itself. Damage to the temporal lobes can also result in visual agnosia, a deficit in which patients are unable to properly recognize objects, either due to a perceptive deficit, or a deficit in semantic memory. In the process of object recognition, visual information from the occipital lobes (such as lines, movement, colour etc.) must at some point be actively interpreted by the brain and attributed meaning. This is commonly referred to in terms of the ventral, or "what" pathway, which leads to the temporal lobes. People with visual agnosia are often able to identify features of an object (it is small, cylindrical, has a handle etc.), but are unable to recognize the object as a whole (a tea cup). This has been termed specifically as integrative agnosia. was long thought to involve only the structures of the medial temporal lobe. More recent neuroimaging research has begun to demonstrate that the parietal lobe plays an important, though often subtle role in recognition memory as well. Early PET and fMRI studies demonstrated activation of the posterior parietal cortex during recognition tasks, however, this was initially attributed to retrieval activation of precuneus, which was thought involved in reinstating visual content in memory | Biology | https://en.wikipedia.org/wiki?curid=21312318 | Recognition memory | 140,615 |
Recognition memory New evidence from studies of patients with right posterior parietal lobe damage indicates very specific recognition deficits. This damage causes impaired performance on object recognition tasks with a variety of visual stimuli, including colours, familiar objects, and new shapes. This performance deficit is not a result of source monitoring errors, and accurate performance on recall tasks indicates that the information has been encoded. Damage to the posterior parietal lobe therefore does not cause global memory retrieval errors, only errors on recognition tasks. Lateral parietal cortex damage (either dextral or sinistral) impairs performance on recognition memory tasks, but does not affect source memories. What is remembered is more likely to be of the 'familiar', or 'know' type, rather than 'recollect' or 'remember', indicating that damage to the parietal cortex impairs the conscious experience of memory. There are several hypotheses that seek to explain the involvement of the posterior parietal lobe in recognition memory. The attention to memory model (AtoM) posits that the posterior parietal lobe could play the same role in memory as it does in attention: mediating top-down versus bottom-up processes. Memory goals can either be deliberate (top-down) or in response to an external memory cue (bottom-up). The superior parietal lobe sustains top-down goals, those provided by explicit directions | Biology | https://en.wikipedia.org/wiki?curid=21312318 | Recognition memory | 140,616 |
Recognition memory The inferior parietal lobe can cause the superior parietal lobe to redirect attention to bottom-up driven memory in the presence of an environmental cue. This is the spontaneous, non-deliberate memory process involved in recognition. This hypothesis explains many findings related to episodic memory, but fails to explain the finding that diminishing the top-down memory cues given to patients with bilateral posterior parietal lobe damage had little effect on memory performance. A new hypothesis explains a greater range of parietal lobe lesion findings by proposing that the role of the parietal lobe is in the subjective experience of vividness and confidence in memories. This hypothesis is supported by findings that lesions on the parietal lobe cause the perception that memories lack vividness, and give patients the feeling that their confidence in their memories is compromised. The output-buffer hypothesis of the parietal cortex postulates that parietal regions help hold the qualitative content of memories for retrieval, and make them accessible to decision-making processes. Qualitative content in memories helps to distinguish those recollected, so impairment of this function reduces confidence in recognition judgments, as in parietal lobe lesion patients. Several other hypotheses attempt to explain the role of the parietal lobe in recognition memory | Biology | https://en.wikipedia.org/wiki?curid=21312318 | Recognition memory | 140,617 |
Recognition memory The mnemonic-accumulator hypothesis postulates that the parietal lobe holds a memory strength signal, which is compared with internal criteria to make old/new recognition judgments. This relates to signal-detection theory, and accounts for recollected items being perceived as 'older' than familiar items. The attention to internal representation hypothesis posits that parietal regions shift and maintain attention to memory representations. This hypothesis relates to the AtoM model, and suggests that parietal regions are involved in deliberate, top-down intention to remember. A possible mechanism of the parietal lobe's involvement in recognition memory may be differential activation for recollected versus familiar memories, and old versus new stimuli. This region of the brain shows greater activation during segments of recognition tasks containing primarily old stimuli, versus primarily new stimuli. A dissociation between the dorsal and ventral parietal regions has been demonstrated, with the ventral region experiencing more activation for recollected items, and the dorsal region experiencing more activation for familiar items. Anatomy provides further clues to the role of the parietal lobe in recognition memory. The lateral parietal cortex shares connections with several regions of the medial temporal lobe, including its hippocampal, parahippocampal, and entorhinal regions. These connections may facilitate the influence of the medial temporal lobe in cortical information processing | Biology | https://en.wikipedia.org/wiki?curid=21312318 | Recognition memory | 140,618 |
Recognition memory Evidence from amnesic patients have shown that lesions in the right frontal lobe are a direct cause of false recognition errors. Some suggest this is due to a variety of factors including defective monitoring, retrieval and decision processes. Patients with frontal lobe lesions also showed evidence of marked anterograde and relatively mild retrograde face memory impairment. The ability to recognize stimuli as old or new has significant evolutionary advantages for humans. Discerning between familiar and unfamiliar stimuli allows for rapid threat appraisals in often hostile environments. The speed and accuracy of an old/new recognition judgment are two components in a series of cognitive processes that allow humans to identify and respond to potential dangers in their environments. Recognition of a prior occurrence is one adaptation that provides a cue of the utility of information to decision-making processes. The perirhinal cortex is notably involved in both the fear response and recognition memory. Neurons in this region activate strongly in response to new stimuli, and activate less frequently as familiarity with the stimulus increases. Information regarding stimulus identity arrives at the hippocampus via the perirhinal cortex, with the perirhinal system contributing a rapid, automatic appraisal of the familiarity of the stimuli and the recency of its presentation | Biology | https://en.wikipedia.org/wiki?curid=21312318 | Recognition memory | 140,619 |
Recognition memory This recognition response has the distinct evolutionary advantage of providing information for decision-making processes in an automated, expedient, and non-effortful manner, allowing for faster responses to threats. A practical application of recognition memory is in relation to developing multiple choice tests in an academic setting. A "good" test does not tap recognition memory, it wants to discern how well a person encoded and can recall a concept. If people rely on recognition for use on a memory test (such as multiple choice) they may recognize one of the options but this does not necessarily mean it is the correct answer. | Biology | https://en.wikipedia.org/wiki?curid=21312318 | Recognition memory | 140,620 |
NeuroLex is a dynamic lexicon of neuroscience concepts. It is a structured as a semantic wiki, using Semantic MediaWiki. is supported by the Neuroscience Information Framework project. The is intended to help improve the way that neuroscientists communicate about their data, so that information systems like the NIF can find data more easily and provide more powerful means of integrating data that occur across distributed resources. One of the big roadblocks to data integration in neuroscience is the inconsistent use of terminology in databases and other resources like the literature. When one uses the same terms to mean different things, one cannot easily ask questions that span across multiple resources. For example, if three databases have information about what genes are expressed in cortex, but they all use different definitions of cerebral cortex, then one cannot compare them easily. The NIF enables discovery and access to public research data and tools worldwide through an open source, networked environment. Funded by the NIH Blueprint for Neuroscience Research, the NIF enables scientists and students to discover global neuroscience web resources that cut across traditional boundaries – from experimental, clinical and translational neuroscience databases, to knowledge bases, atlases, and genetic/genomic resources | Biology | https://en.wikipedia.org/wiki?curid=21316635 | NeuroLex | 140,621 |
NeuroLex Unlike general search engines, NIF provides deeper access to a more focused set of resources that are relevant to neuroscience, search strategies tailored to neuroscience, and access to content that is traditionally “hidden” from web search engines. The Framework is a dynamic inventory of neuroscience databases, annotated and integrated with a unified system of biomedical terminology (i.e. NeuroLex). NIF supports concept-based queries across multiple scales of biological structure and multiple levels of biological function, making it easier to search for and understand the results. As part of the NIF, a search interface to many different sources of neuroscience information and data is provided. To make this search more effective, the NIF is constructing ontologies to help organize neuroscience concepts into category hierarchies, e.g. stating that a neuron is a cell. This allows users to perform more effective searches and also to organize and understand the information that is returned. But an important adjunct to this activity is to clearly define all of the terms that are used to describe data, e.g., anatomical terms, techniques, organism names. The initial entries in the were built from the NIFSTD ontologies which subsumed an earlier vocabulary BIRNLex. It currently contains concepts that span gross anatomy, cells of the nervous system, subcellular structures, diseases, functions and techniques. NIF is soliciting community input to add more content and correct what is there | Biology | https://en.wikipedia.org/wiki?curid=21316635 | NeuroLex | 140,622 |
NeuroLex NIF was featured in a special issue of "Neuroinformatics", published in September 2008: | Biology | https://en.wikipedia.org/wiki?curid=21316635 | NeuroLex | 140,623 |
Mitophagy is the selective degradation of mitochondria by autophagy. It often occurs to defective mitochondria following damage or stress. The process of mitophagy was first described over a hundred years ago by Lewis and Lewis. Ashford and Porter used electron microscopy to observe mitochondrial fragments in liver lysosomes by 1962, and a 1977 report suggested that "mitochondria develop functional alterations which would activate autophagy." The term "mitophagy" was in use by 1998. is key in keeping the cell healthy. It promotes turnover of mitochondria and prevents accumulation of dysfunctional mitochondria which can lead to cellular degeneration. It is mediated by Atg32 (in yeast) and NIX and its regulator BNIP3 in mammals. is regulated by PINK1 and parkin proteins. In addition to the selective removal of damaged mitochondria, mitophagy is also required to adjust mitochondrial numbers to changing cellular metabolic needs, for steady-state mitochondrial turnover, and during certain cellular developmental stages, such as during cellular differentiation of red blood cells. Organelles and bits of cytoplasm are sequestered and targeted for degradation by the lysosome for hydrolytic digestion by a process known as autophagy. Mitochondria metabolism leads to the creation of by-products that lead to DNA damage and mutations. Therefore, a healthy population of mitochondria is critical for the well-being of cells | Biology | https://en.wikipedia.org/wiki?curid=21317821 | Mitophagy | 140,624 |
Mitophagy Previously it was thought that targeted degradation of mitochondria was a stochastic event, but accumulating evidence suggest that mitophagy is a selective process. Generation of ATP by oxidative phosphorylation leads to the production of various reactive oxygen species (ROS) in the mitochondria, and submitochondrial particles. Formation of ROS as a mitochondrial waste product will eventually lead to cytotoxicity and cell death. Because of their role in metabolism, mitochondria are very susceptible to ROS damage. Damaged mitochondria cause a depletion in ATP and a release of cytochrome "c", which leads to activation of caspases and onset of apoptosis. Mitochondrial damage is not caused solely by oxidative stress or disease processes; normal mitochondria will eventually accumulate oxidative damage hallmarks overtime, which can be deleterious to mitochondria as well as to the cell. These faulty mitochondria can further deplete the cell from ATP, increase production of ROS, and release proapoptopic proteins such as caspases. Because of the danger of having damaged mitochondria in the cell, the timely elimination of damaged and aged mitochondria is essential for maintaining the integrity of the cell. This turnover process consists of the sequestration and hydrolytic degradation by the lysosome, a process also known as mitophagy. Mitochondrial depletion reduces a spectrum of senescence effectors and phenotypes while preserving ATP production via enhanced glycolysis | Biology | https://en.wikipedia.org/wiki?curid=21317821 | Mitophagy | 140,625 |
Mitophagy There are several pathways by which mitophagy is induced in mammalian cells. The PINK1 and Parkin pathway is, so far, the best characterized. This pathway starts by deciphering the difference between healthy mitochondria and damaged mitochondria. A 64-kDa protein, PTEN-induced kinase 1 (PINK1), has been implicated to detect mitochondrial quality. PINK1 contains a mitochondrial targeting sequence (MTS) and is recruited to the mitochondria. In healthy mitochondria, PINK1 is imported through the outer membrane via the TOM complex, and partially through the inner mitochondrial membrane via the TIM complex, so it then spans the inner mitochondrial membrane. The process of import into the inner membrane is associated with the cleavage of PINK1 from 64-kDa into 60-kDa. PINK1 is then cleaved by PARL into 52-kDa. This new form of PINK1 is degraded by proteases within the mitochondria. This keeps the concentration of PINK1 in check in healthy mitochondria. In unhealthy mitochondria, the inner mitochondrial membrane becomes depolarized. This membrane potential is necessary for the TIM-mediated protein import. In depolarized mitochondria, PINK1 is no longer imported into the inner membrane, is not cleaved by PARL and PINK1 concentration increases in the outer mitochondrial membrane. PINK1 can then recruit Parkin. It is thought that PINK1 phosphorylates Parkin ubiquitin ligase at S65 which initiates Parkin recruitment at the mitochondria. Parkin is a cytosolic E3 ubiquitin ligase | Biology | https://en.wikipedia.org/wiki?curid=21317821 | Mitophagy | 140,626 |
Mitophagy Once localized at the mitochondria, PINK1 phosphorylates Parkin at S65, homologous to the site where ubiquitin was phosphorylated, which activates Parkin by inducing dimerization and an active state. This allows for Parkin mediated ubiquitination on other proteins. Because of the PINK1 mediated recruitment to the mitochondrial surface, Parkin can ubiquitylate proteins in the outer mitochondrial membrane. Some of these proteins include Mfn1/Mfn2 and mitoNEET. The ubiquitylation of mitochondrial surface proteins brings in mitophagy initiating factors. Parkin promotes ubiquitin chain linkages on both K63 and K48. K48 ubiquitination initiates degradation of the proteins, and could allow for passive mitochondrial degradation. K63 ubiquitination is thought to recruit autophagy adaptors LC3/GABARAP which will then lead to mitophagy. It is still unclear which proteins are necessary and sufficient for mitophagy, and how these proteins, once ubiquitylated, initiate mitophagy. Other pathways that can induce mitophagy includes mitophagy receptors on the outer mitochondrial membrane surface. These receptors include NIX1, BNIP3 and FUNDC1. All of these receptors contain LIR consensus sequences that bind LC3/GABARAP which can lead to the degradation of the mitochondria. In hypoxic conditions BNIP3 is upregulated by HIF1α. BNIP3 is then phosphorylated at its serine residues near the LIR sequence which promotes LC3 binding | Biology | https://en.wikipedia.org/wiki?curid=21317821 | Mitophagy | 140,627 |
Mitophagy FUNDCI is also hypoxia sensitive, although it is constitutively present at the outer mitochondrial membrane during normal conditions In neurons, mitochondria are distributed unequally throughout the cell to areas where energy demand is high, like at synapses and Nodes of Ranvier. This distribution is maintained largely by motor protein-mediated mitochondrial transport along the axon. While neuronal mitophagy is thought to occur primarily in the cell body, it also occurs locally in the axon at sites distant from the cell body; in both the cell body and the axon, neuronal mitophagy occurs via the PINK1-Parkin pathway. in the nervous system may also occur transcellularly, where damaged mitochondria in retinal ganglion cell axons can be passed to neighboring astrocytes for degradation. This process is known as transmitophagy. in yeast was first presumed after the discovery of Yeast Mitochondrial Escape genes (yme), specifically yme1. Yme1 like other genes in the family showed increase escapes of mtDNA, but was the only one that showed in increase in mitochondrial degradation. Through work on this gene that mediates the escape of mtDNA, researchers discovered that mitochondrial turnover is triggered by proteins. More was discovered about genetic control of mitophagy after studies done of UTH1. After doing a screen for genes that regulate longevity. It was found in ΔUTH1 strains there was an inhibition of mitophagy, which occurred without affecting autophagy mechanisms | Biology | https://en.wikipedia.org/wiki?curid=21317821 | Mitophagy | 140,628 |
Mitophagy It also showed that Uth1p protein is necessary to move mitochondria to the vacuole. This suggested there is a specialized system for mitophagy. Other studies looked at AUP1, a mitochondrial phosphatase, and found Aup1 marks mitochondria for elimination. Another yeast protein associated with mitophagy is a mitochondrial inner membrane protein, Mdm38p/Mkh1p. This protein is part of the complex that exchanges K+/H+ ions across the inner membrane. Deletions to this protein causes swelling, a loss of membrane potential, and mitochondrial fragmentation. Recently, it has been shown that ATG32 (autophagy related gene 32) plays a crucial role in yeast mitophagy. It is localized to the mitochondria. Once mitophagy is initiated, Atg32 binds to Atg11 and the Atg32-associated mitochondria is transported to the vacuole. Atg32 silencing stops recruitment of autophagy machinery and mitochondrial degradation. Atg32 is not necessary for other forms of autophagy. All of these proteins likely play a role in maintaining a healthy mitochondria, but mutations have shown that dysregulation can lead to a selective degradation of mitochondria. Whether these proteins work in concert, are main players in mitophagy, or the networks controlled still remain to be elucidated In 1920 Otto Warburg observed that certain cancerous tumors display a metabolic shift towards glycolysis | Biology | https://en.wikipedia.org/wiki?curid=21317821 | Mitophagy | 140,629 |
Mitophagy This is referred to as the "Warburg effect", in which cancer cells produce energy via the conversion of glucose into lactate, even in the presence of oxygen (aerobic glycolysis). Despite nearly a century since it was first described, a lot of questions remained unanswered regarding the Warburg effect. Initially, Warburg attributed this metabolic shift to mitochondrial dysfunction in cancer cells. Further studies in tumor biology have shown that the increased growth rate in cancer cells is due to an overdrive in glycolysis (glycolytic shift), which leads to a decrease in oxidative phosphorylation and mitochondrial density. As a consequence of the Warburg effect, cancer cells would produce large amounts of lactate. The excess lactate is then released to the extracellular environment which results in a decrease in extracellular pH. This micro-environment acidification can lead to cellular stress, which would lead to autophagy. Autophagy is activated in response to a range of stimuli, including nutrient depletion, hypoxia, and activated oncogenes. However, it appears that autophagy can help in cancer cell survival under conditions of metabolic stress and it may confer resistance to anti-cancer therapies such as radiation and chemotherapy. Additionally, in the microenvironment of cancer cells, there is an increase in hypoxia-inducible transcription factor 1-alpha (HIF1A), which promotes expression of BNIP3, an essential factor for mitophagy | Biology | https://en.wikipedia.org/wiki?curid=21317821 | Mitophagy | 140,630 |
Mitophagy Parkinson's disease is a neurodegenerative disorder pathologically characterized by death of the dopamine-producing neurons in the substantia nigra. There are several genetic mutations implicated in Parkinson's disease, including loss of function PINK1 and Parkin. Loss of function in either of these genes results in accumulation of damaged mitochondria and aggregation of proteins – eventually leading to neuronal death. Mitochondria dysfunction is thought to be involved in Parkinson's disease pathogenesis. In spontaneous, usually aging related Parkinson's disease (non-genetically linked), the disease is commonly caused by dysfunctional mitochondria, cellular oxidative stress, autophagic alterations and the aggregation of proteins. These can lead to mitochondrial swelling and depolarization. It is important to keep the dysfunctional mitochondria regulated, because all of these traits could be induced by mitochondrial dysfunction and can induce cell death. Disorders in energy creation by mitochondria can cause cellular degeneration, like those seen in the substantia nigra. | Biology | https://en.wikipedia.org/wiki?curid=21317821 | Mitophagy | 140,631 |
Genome Reference Consortium The (GRC) is an international collective of academic and research institutes with expertise in genome mapping, sequencing, and informatics, formed to improve the representation of reference genomes. At the time the human reference was initially described, it was clear that some regions were recalcitrant to closure with existing technology. The main reason for improving the reference assemblies are that they are the cornerstones upon which all whole genome studies are based (e.g. the 1000 Genomes Project). The GRC is a collaborative effort which interacts with various groups in the scientific community, however the primary member institutes are: Initially the focus lies with the Human and the Mouse reference genomes, but in mid-late 2010 full maintenance and improvement of the Zebrafish genome sequence was also added to the GRC. The goal of the Consortium is to correct the small number of regions in the reference that are currently misrepresented, to close as many remaining gaps as possible and to produce alternative assemblies of structurally variant loci when necessary. As of September 2019, the major assembly releases for human, mouse, zebrafish, and chicken are GRCh38, GRCm38, GRCz11, and GRCg6a respectively. Major assembly releases do not follow a fixed cycle, however there are "minor" assembly updates in the form of genome patches which either correct errors in the assembly or add additional alternate loci | Biology | https://en.wikipedia.org/wiki?curid=21323317 | Genome Reference Consortium | 140,632 |
Genome Reference Consortium These assemblies are represented in various genome browsers and databases including Ensembl, those in NCBI and UCSC Genome Browser. Institute Homepages | Biology | https://en.wikipedia.org/wiki?curid=21323317 | Genome Reference Consortium | 140,633 |
Nuffield Council on Bioethics The is a UK-based independent charitable body, which examines and reports on bioethical issues raised by new advances in biological and medical research. Established in 1991, the Council is funded by the Nuffield Foundation, the Medical Research Council and the Wellcome Trust. The Council has been described by the media as a 'leading ethics watchdog', which 'never shrinks from the unthinkable'. The was set up in response to concerns about the lack of a national body responsible for evaluating the ethical implications of developments in biomedicine and biotechnology. Its terms of reference are: The Council selects topics to examine through a horizon scanning programme, which aims to identify developments relevant to biological and medical research. Members of the Council meet quarterly to discuss and contribute to ongoing work, review recent advances in medical and biological research that raise ethical questions and choose topics for further exploration. The Council is well known for its in-depth inquiries which usually take 18-24 months and are overseen by an expert working group, informed by extensive consultation and research. The Chair of the is appointed by the Nuffield Foundation in consultation with the other funders. Chairs are appointed for five years. Council members are drawn from relevant fields of expertise including science, medicine, sociology, philosophy and law, for an initial period of three years, with the possibility of an additional three-year term | Biology | https://en.wikipedia.org/wiki?curid=21325256 | Nuffield Council on Bioethics | 140,634 |
Nuffield Council on Bioethics When vacancies arise, the Council advertises widely. The Council's Membership Advisory group considers and makes recommendations to the Council on future members selected from the respondents to advertisements. Hugh Whittall has been the Director of the Council since February 2007. Former Directors: Current Previous members The Council's recommendations to policy makers have often been described as 'influential'. The Council was entirely funded by the Nuffield Foundation from 1991 to 1994. Since 1994, the Council has been jointly funded by the Nuffield Foundation, the Medical Research Council and The Wellcome Trust on a five-year rolling system. Towards the end of each five-year period, a process of external review is a condition of continued support. Funding has been confirmed until 2022 following the satisfactory completion of the latest funding bid. The Council takes the view that its terms of reference do not require it to adopt the same ethical framework or set of principles in all reports. The Council is therefore not bound by the values of particular schools of philosophy (for example, utilitarianism, deontology, virtue ethics) or approaches in bioethics, such as the 'four principles of bioethics' (autonomy, justice, beneficence, non-maleficence), or the Barcelona Principles (autonomy, dignity, integrity, vulnerability) | Biology | https://en.wikipedia.org/wiki?curid=21325256 | Nuffield Council on Bioethics | 140,635 |
Nuffield Council on Bioethics In 2006-7, John Harris, Professor of Bioethics at the University of Manchester, and Dr Sarah Chan carried out an external review of the way ethical frameworks, principles, norms and guiding concepts feature in the Council's publications. The authors found that the ethical frameworks used in the Council's publications had become increasingly explicit and transparent. | Biology | https://en.wikipedia.org/wiki?curid=21325256 | Nuffield Council on Bioethics | 140,636 |
Pre-B-cell leukemia homeobox (PBX) refers to a family of transcription factors. Types include: | Biology | https://en.wikipedia.org/wiki?curid=21332803 | Pre-B-cell leukemia homeobox | 140,637 |
Journal of the Marine Biological Association of the United Kingdom The is a peer-reviewed scientific journal that was established in August 1887. Originally set up to provide members of the Marine Biological Association of the United Kingdom with "notes and reports concerning the work of the Association" along with "brief records of observations relating to the marine biology and fisheries of the coasts of the United Kingdom". Since 1937 the journal has been published by Cambridge University Press on behalf of the association. According to the "Journal Citation Reports", the journal has a 2017 impact factor of 1.403. | Biology | https://en.wikipedia.org/wiki?curid=21335541 | Journal of the Marine Biological Association of the United Kingdom | 140,638 |
African Journal of Ecology The (formerly "East African Wildlife Journal") is a quarterly scientific journal focused on the ecology and conservation of the animals and plants of Africa. It is published by Blackwell Publishing in association with the East African Wildlife Society. | Biology | https://en.wikipedia.org/wiki?curid=21344716 | African Journal of Ecology | 140,639 |
PhyloXML is an XML language for the analysis, exchange, and storage of phylogenetic trees (or networks) and associated data. The structure of phyloXML is described by XML Schema Definition (XSD) language. A shortcoming of current formats for describing phylogenetic trees (such as Nexus and Newick/New Hampshire) is a lack of a standardized means to annotate tree nodes and branches with distinct data fields (which in the case of a basic species tree might be: species names, branch lengths, and possibly multiple support values). Data storage and exchange is even more cumbersome in studies in which trees are the result of a reconciliation of some kind: To alleviate this, a variety of ad-hoc, special purpose formats have come into use (such as the NHX format, which focuses on the needs of gene-function and phylogenomic studies). A well defined XML format addresses these problems in a general and extensible manner and allows for interoperability between specialized and general purpose software. An example of a program for visualizing phyloXML is Archaeopteryx. | Biology | https://en.wikipedia.org/wiki?curid=21356135 | PhyloXML | 140,640 |
Władysław Szafer Institute of Botany The (Instytut Botaniki im. Władysława Szafera, Polish) in Kraków, Poland is a major European herbarium containing a collection of over 650,000 vascular plants, bryophytes, algae, fungi, lichens, and various plant fossils. The vascular plant specimens are primarily from Central Europe with a specialization in alpine plants. The bryophytes are Polish, Antarctic and subAntarctic, and East African. The fossil plants are largely Central European. Main publications include "Acta Palaeobotanica", and the "Polish Botanical Journal". The herbarium was established in the 1950s by professor of botany and paleobotany, Władysław Szafer, at the Jagiellonian University in Kraków. | Biology | https://en.wikipedia.org/wiki?curid=21358560 | Władysław Szafer Institute of Botany | 140,641 |
40 Days and 40 Nights (book) 40 Days and 40 Nights: Darwin, Intelligent Design, God, OxyContin, and Other Oddities on Trial in Pennsylvania is a 2007 non fiction book about the "Kitzmiller v. Dover Area School District" trial of 2005. Author Matthew Chapman, a journalist, screenwriter and director (and the great-great-grandson of Charles Darwin) reported on the trial for Harper's magazine. Austin Cline of "About.com" gave the book four-and-a-half-stars-out-of-five rating, stating: "There are bound to be many books written about this trial and I don't know if Chapman's will be the best source of information — either about the trial itself or the larger issues involved. It will, however, almost certainly stand out as one of the most enjoyable and entertaining to read." John Dupuis of "ScienceBlogs" gave the book a positive review, saying that "Chapman uses some of the same strategies in the Dover as he did in the first book on the Scopes Trial. He tells the story of the trial as a story about people: the lawyers, the defendants, the townspeople, the media. And a colourful lot they were, making those aspects of the book very entertaining and compelling. The weakness of the book is related to those colourful characters — the chronicle of the trial itself never really seemed to come alive for me in the same way that his telling of the Scopes trial did." | Biology | https://en.wikipedia.org/wiki?curid=21359384 | 40 Days and 40 Nights (book) | 140,642 |
Ub-AMC Ubiquitin-AMC is a fluorogenic substrate for a wide range of deubiquitinating enzymes (DUBs), including ubiquitin C-terminal hydrolases (UCHs) and ubiquitin specific proteases (USPs). It is a particularly useful reagent for the study of deubiquitinating activity where detection sensitivity or continuous monitoring of activity is essential. Ubiquitin-AMC is prepared by the C-terminal derivatization of ubiquitin with 7-amino-4-methylcoumarin and has been shown to be a useful and sensitive fluorogenic substrate for wide range of deubiquitinylating enzymes (DUBs), including ubiquitin C-terminal hydrolases (UCHs) and ubiquitin specific proteases (USPs). Ubiquitin-AMC has been shown to be a sensitive substrate for UCH-L3 (Km = 0.039µM) and for Isopeptidase-T (Km = 0.17-1.4µM), and is particularly useful for studying deubiquitinylating activity where detection sensitivity or continuous monitoring of activity is essential. Typical assay set-up: Assay substrate concentration: 0.01-1.0µM. Enzyme concentrations, UCH-L3: 10-100pM, isopeptidase-T: 10-100nM. Release of AMC fluorescence by DUB enzymes can be monitored using 380 nm excitation and 460 nm emission wavelengths. | Biology | https://en.wikipedia.org/wiki?curid=21359548 | Ub-AMC | 140,643 |
Organography (from Greek , "organo", "organ"; and , "-graphy") is the scientific description of the structure and function of the organs of living things. as a scientific study starts with Aristotle, who considered the parts of plants as "organs" and began to consider the relationship between different organs and different functions. In the 17th century Joachim Jung, clearly articulated that plants are composed of different organ types such as root, stem and leaf, and he went on to define these organ types on the basis of form and position. In the following century Caspar Friedrich Wolff was able to follow the development of organs from the "growing points" or apical meristems. He noted the commonality of development between foliage leaves and floral leaves (e.g. petals) and wrote: "In the whole plant, whose parts we wonder at as being, at the first glance, so extraordinarily diverse, I finally perceive and recognize nothing beyond leaves and stem (for the root may be regarded as a stem). Consequently all parts of the plant, except the stem, are modified leaves." Similar views were propounded at by Goethe in his well-known treatise | Biology | https://en.wikipedia.org/wiki?curid=21360243 | Organography | 140,644 |
Organography He wrote: "The underlying relationship between the various external parts of the plant, such as the leaves, the calyx, the corolla, the stamens, which develop one after the other and, as it were, out of one another, has long been generally recognized by investigators, and has in fact been specially studied; and the operation by which one and the same organ presents itself to us in various forms has been termed Metamorphosis of Plants." | Biology | https://en.wikipedia.org/wiki?curid=21360243 | Organography | 140,645 |
Institute of Biophysics, Chinese Academy of Sciences The Institute of Biophysics, Chinese Academy of Sciences, based in Beijing, China, focuses on biophysically oriented basic research in the life sciences. It was established by Bei Shizhang in 1958, from the former Beijing Experimental Biology Institute founded in 1957. Xu Tao is the current Director. The main research focus of the Institute is on the fields of protein science and brain & cognitive sciences. The Institute has two National Key Laboratories—"The National Laboratory of Biomacromolecules" and "The State Laboratory of Brain and Cognitive Sciences". Establishment of the National Laboratory of Protein Science was given approval by China's Ministry of Science and Technology (MOST) in December 2006. Research in the field of protein science emphasizes the following areas: 3D-structure and function of proteins, bio-membranes and membrane proteins, protein translation and folding, protein interaction networks, the molecular basis of infection and immunity, the molecular basis of sensation and cognition, protein and peptide drugs, and new techniques and methods in protein science research. Research areas in brain and cognitive sciences include neural processes and mechanisms in complex cognition, expression of visual perception and attention, neural mechanisms of perceptional information processing, and dysfunction in brain cognition | Biology | https://en.wikipedia.org/wiki?curid=21365746 | Institute of Biophysics, Chinese Academy of Sciences | 140,646 |
Institute of Biophysics, Chinese Academy of Sciences The Institute has received National Natural Science Foundation, '973', '863', 'Knowledge Innovation Program' and other major research grants, supporting outstanding research in a range of areas. The achievements of the Institute in terms of awards, publications, patents, and applied research maintain the Institute at the highest level nationally, and it has worldwide recognition for research in the life sciences. Among other connections, since 2008 it has hosted an intensive course in macromolecular crystallography as a resource closely modeled on the course at Cold Spring Harbor Laboratory on Long Island, USA, and involving both US and Chinese instructors. The Biophysical Society of China is affiliated with the Institute. It takes responsibility for editing two core national natural science journals, namely Progress in Biochemistry & Biophysics and Acta Biophysica Sinica. Of these, Progress in Biochemistry & Biophysics is indexed in the SCI－E database. The institute has a library (1100 square meters) with 28,000 books, more than 33,000 journals, and 11 databases. Library users can use the internet to access about 2,500 foreign e-journals. The Institute has a research team, with about 400 staff members, 500 graduate students and 60 visiting scholars and post-docs. Within the scientific staff, there are 89 Principal Investigators and three technical specialists, of whom 14 are members of the Chinese Academy of Sciences | Biology | https://en.wikipedia.org/wiki?curid=21365746 | Institute of Biophysics, Chinese Academy of Sciences | 140,647 |
Institute of Biophysics, Chinese Academy of Sciences 28 have received awards from the "100 Talents Program of the Chinese Academy of Sciences" and 30 have received the "National Outstanding Young Scientists Award". | Biology | https://en.wikipedia.org/wiki?curid=21365746 | Institute of Biophysics, Chinese Academy of Sciences | 140,648 |
Wiley Prize The in Biomedical Sciences is intended to recognize breakthrough research in pure or applied life science research that is distinguished by its excellence, originality and impact on our understanding of biological systems and processes. The award may recognize a specific contribution or series of contributions that demonstrate the nominee’s significant leadership in the development of research concepts or their clinical application. Particular emphasis will be placed on research that champions novel approaches and challenges accepted thinking in the biomedical sciences. The Wiley Foundation, established in 2001, is the endowing body that supports the in Biomedical Sciences. This international award is presented annually and consists of a $35,000 prize and a luncheon in honor of the recipient. The award is presented at a ceremony at The Rockefeller University, where the recipient delivers an honorary lecture as part of the Rockefeller University Lecture Series. As of 2016, six recipients have gone on to be awarded the Nobel Prize in Physiology or Medicine. Source: Wiley Foundation Dr. H. Robert Horvitz of the Massachusetts Institute of Technology and Dr. Stanley J. Korsmeyer of the Dana Farber Cancer Institute - For his seminal research on programmed cell death and the discovery that a genetic pathway accounts for the programmed cell death within an organism, and Dr. Korsmeyer was chosen for his discovery of the relationship between human lymphomas and the fundamental biological process of apoptosis | Biology | https://en.wikipedia.org/wiki?curid=21368349 | Wiley Prize | 140,649 |
Wiley Prize Notably, Dr. Korsmeyer's experiments established that blocking cell death plays a primary role in cancer. Dr. Andrew Z. Fire, of both the Carnegie Institution of Washington and the Johns Hopkins University; Dr. Craig C. Mello, of the University of Massachusetts Medical School; Dr. Thomas Tuschl, formerly of the Max-Planck Institute for Biophysical Chemistry in Goettingen, Germany, and most recently of The Rockefeller University; and Dr. David Baulcombe, of the Sainsbury Laboratory at the John Innes Centre in Norwich, England - For contributions to discoveries of novel mechanisms for regulating gene expression by small interfering RNAs (siRNA). C. David Allis, Ph.D., Joy and Jack Fishman, Professor, Laboratory of Chromatin Biology and Epigenetics at the Rockefeller University in New York - For the significant discovery that transcription factors can enzymatically modify histones to regulate gene activity. Dr. Peter Walter, a Howard Hughes Medical Institute investigator, and Professor and Chairman of the Department of Biochemistry & Biophysics at the University of California San Francisco, and Dr. Kazutoshi Mori, a Professor of Biophysics, in the Graduate School of Science at Kyoto University, in Japan - For the discovery of the novel pathway by which cells regulate the capacity of their intracellular compartments to produce correctly folded proteins for export. Dr. Elizabeth H | Biology | https://en.wikipedia.org/wiki?curid=21368349 | Wiley Prize | 140,650 |
Wiley Prize Blackburn, Morris Herztein Professor of Biology and Physiology in the Department of Biochemistry and Biophysics at the University of California, San Francisco, and Dr. Carol Greider, Daniel Nathans Professor and Director of Molecular Biology & Genetics at Johns Hopkins University - For the discovery of telomerase, the enzyme that maintains chromosomal integrity and the recognition of its importance in aging, cancer and stem cell biology. Dr. F. Ulrich Hartl, Director at the Max Planck Institute of Biochemistry, in Munich, Germany, and Dr. Arthur L. Horwich, Eugene Higgins Professor of Genetics and Pediatrics at the Yale University School of Medicine, and Investigator, Howard Hughes Medical Institute. - For elucidation of the molecular machinery that guides proteins into their proper functional shape, thereby preventing the accumulation of protein aggregates that underlie many diseases, such as Alzheimer's and Parkinson's. Dr. Richard P. Lifton of the Yale University School of Medicine. - For the discovery of the genes that cause many forms of high and low blood pressure in humans. Dr. Bonnie Bassler of the Department of Molecular Biology at Princeton University and the Howard Hughes Medical Institute. - For pioneering investigations of quorum sensing, a mechanism that allows bacteria to “talk” to each other to coordinate their behavior, even between species. Dr. Peter Hegemann, Professor of Molecular Biophysics, Humboldt University, Berlin; Dr | Biology | https://en.wikipedia.org/wiki?curid=21368349 | Wiley Prize | 140,651 |
Wiley Prize Georg Nagel, Professor of Molecular Plant Physiology, Department of Botany, University of Würzburg; and Dr. Ernst Bamberg, Professor and Director of the Dept of Biophysical Chemistry, Max Planck Institute for Biophysics, Frankfurt, Germany for their discovery of channelrhodopsins, a family of light-activated ion channels. The discovery has greatly enlarged and strengthened the new field of optogenetics. Channelrhodopsins also provide a high potential for biomedical applications such as the recovery of vision and optical deep brain stimulation for treatment of Parkinson's and other diseases, instead of the more invasive electrode-based treatments. Dr. Lily Jan and Dr. Yuh Nung Jan of Howard Hughes Medical Institute at the University of California, San Francisco for their molecular identification of a founding member of a family of potassium ion channels that control nerve cell activity throughout the animal kingdom. Dr. Michael Sheetz, Columbia University; Dr. James Spudich, Stanford University, and Dr. Ronald Vale, University of California, San Francisco for explaining how cargo is moved by molecular motors along two different systems of tracks within cells. Dr. Michael Young, Rockefeller University; Dr. Jeffrey Hall, Brandeis University (Emeritus), and Dr. Michael Rosbash, Brandeis University for the discovery of the molecular mechanisms governing circadian rhythms. Dr. William Kaelin, Jr.; Dr. Steven McKnight; Dr. Peter J. Ratcliffe; Dr. Gregg L. Semenza for their work in oxygen sensing systems. Dr. Evelyn M | Biology | https://en.wikipedia.org/wiki?curid=21368349 | Wiley Prize | 140,652 |
Wiley Prize Witkin and Dr. Stephen Elledge for their studies of the DNA damage response. Dr. Yoshinori Ohsumi for the discovery of how cells recycle their components in an orderly manner. This process, autophagy (self-eating), is critical for the maintenance and repair of cells and tissues. Joachim Frank, Richard Henderson, and Marin van Heel for pioneering developments in electron microscopy. Lynne E. Maquat for elucidating the mechanism of nonsense-mediated messenger RNA decay. Svante Pääbo and David Reich for sequencing the genomes of ancient humans and extinct relatives. Clifford Brangwynne, Anthony Hyman, and Michael Rosen for a new principle of subcellular compartmentalization based on formation of phase-separated biomolecular condensates. | Biology | https://en.wikipedia.org/wiki?curid=21368349 | Wiley Prize | 140,653 |
List of instruments used in toxicology Instruments used specially in Toxicology are as follows: | Biology | https://en.wikipedia.org/wiki?curid=21370414 | List of instruments used in toxicology | 140,654 |
Elaine Ingham is an American microbiologist and soil biology researcher and founder of Soil Foodweb Inc. She is known as a leader in soil microbiology and research of the soil food web. She is an author of the USDA's "Soil Biology Primer". In 2011, Ingham was named as The Rodale Institute's chief scientist. Ingham earned her PhD from the Colorado State University in 1981. Her doctorate is in Microbiology with an emphasis on soil. Along with her husband Russ (who also has a doctorate from Colorado State University in Zoology, emphasizing nematology), she was offered a post-doctoral fellowship at the Natural Resource Ecology Lab at Colorado State University. In 1985, she accepted a Research Associate Fellowship at the University of Georgia. In 1986, Ingham moved to Oregon State University and joined the faculty in both Forest Science and Botany and Plant Pathology. She remained on faculty until 2001. Ingham has been an Affiliate Professor of Sustainable Living at Maharishi University of Management in Fairfield, Iowa, Adjunct Faculty at Southern Cross University in Lismore, New South Wales from 1999 to 2005, Visiting Professor with Melbourne University from 2004 to 2008, and was Program Chair of the Ecological Society of America from 1999 to 2000. She joined the Rodale Institute in 2011 as chief scientist and left in 2013. Ingham is the founder of Soil Foodweb Inc, which works with soil testing laboratories to assess soil biology | Biology | https://en.wikipedia.org/wiki?curid=21371399 | Elaine Ingham | 140,655 |
Elaine Ingham Recently, Ingham has become Director of Research at the Environment Celebration Institute's Farm near Berry Creek in Northern California, demonstrating the methods of biological agriculture to grow plants without pesticides or inorganic fertilizers. See Dr. Ingham's website for the full list of her publications | Biology | https://en.wikipedia.org/wiki?curid=21371399 | Elaine Ingham | 140,656 |
Synapto-pHluorin is a genetically encoded optical indicator of vesicle release and recycling. It is used in neuroscience to study transmitter release. It consists of a pH-sensitive form of green fluorescent protein (GFP) fused to the luminal side of a vesicle-associated membrane protein (VAMP). At the acidic pH inside transmitter vesicles, synapto-pHluorin is non-fluorescent (quenched). When vesicles get released, synapto-pHluorin is exposed to the neutral extracellular space and the presynaptic terminal becomes brightly fluorescent. Following endocytosis, vesicles become re-acidified and the cycle can start again. Chemical alkalinization of all vesicles is often used for normalization of the synapto-pHluorin signals. sometimes consists of yellow fluorescent protein (YFP) to monitor the cytoplasm because its pK is higher than GFP (7.1 versus 6.0). was invented by Gero Miesenböck in 1998. In 2006, an improved version was published, using synaptophysin to target the GFP to vesicles. In 2013, a two-color release sensor (ratio-sypHy) was introduced to determine the size of the recycling pool at individual synapses. is mainly used by neurobiologists to study transmitter release and recycling at presynaptic terminals. It has also been applied to the study of insulin secretion in beta cells of the pancreas. | Biology | https://en.wikipedia.org/wiki?curid=21377466 | Synapto-pHluorin | 140,657 |
Gynodioecy is a rare breeding system that is found in certain flowering plant species in which female and hermaphroditic plants coexist within a population. is the evolutionary intermediate stage between hermaphroditism (exhibiting both female and male parts) and dioecy (having two distinct morphs: male and female). is the opposite of androdioecy, which is a breeding system consisting of male and hermaphroditic plants in a population. occurs as a result of a genetic mutation that inhibits a hermaphroditic plant from producing pollen, while keeping the female reproductive parts intact. is extremely rare, with fewer than 1% of angiosperm species exhibiting the breeding system. Some notable species that exhibit a gynodioecious mating system include "Beta vulgaris" (wild beet), "Lobelia siphilitica", "Silene", and Lamiaceae. is often referred to as the evolutionary intermediate state between hermaphroditism and dioecy. has been investigated by biologists dating as far back as to Charles Darwin. can evolve from hermaphroditism due to certain environmental factors. If enough resources in a population are allocated to the female functions in a hermaphroditic species, gynodioecy will ensue. On the other hand, if more of those resources are divvied up to favor a hermaphrodite’s male functions, androdioecy will result. A high rate of self-pollination in a population facilitates the maintenance of gynodioecy by increasing the inbreeding costs for hermaphrodites | Biology | https://en.wikipedia.org/wiki?curid=21378333 | Gynodioecy | 140,658 |
Gynodioecy Thus, as the rate of inbreeding increases in a population, the more likely gynodioecy is to occur. Since hermaphrodites can reproduce on their own, they are referred to as being self-compatible. On the contrary, non-hermaphroditic plants are self-incompatible. Research has shown that a species can be either gynodioecious or self-incompatible, but very rarely is there a co-occurrence between the two. Therefore, gynodioecy and self-incompatibility tend to prevent each other’s maintenance. Self-incompatibility of plants helps maintain androdioecy in plants, since males are in competition with only hermaphrodites to sire ovules. Self-incompatibility leads to a loss in gynodioecy, since neither hermaphrodites nor females have to deal with inbreeding depression. Two scenarios have been proposed to explain the evolutionary dynamics of the maintenance of gynodioecy. The first scenario, known as the balancing selection theory, considers the genetic factors that control gynodioecy over long evolutionary time scales. The balancing selection leads to cycles that explain the normal sex ratios in gynodioecious populations. The second scenario, known as epidemic dynamics, involves the arrival and loss of new cytoplasmic male sterility genes in new populations. These are the same genes that invade hermaphrodite populations and eventually result in gynodioecy. is determined as a result of a genetic mutation that stops a plant from producing pollen, but still allows normal female reproductive features | Biology | https://en.wikipedia.org/wiki?curid=21378333 | Gynodioecy | 140,659 |
Gynodioecy In plants, nuclear genes are inherited from both parents, but all the cytoplasmic genes come from the mother. This holds true in order to compensate for male gametes being smaller and more motile while female gametes are larger. It makes sense for most plants to be hermaphrodites, since they are sessile and unable to find mates as easily as animals can. Cytoplasmic male sterility genes, usually found in the mitochondrial genome, show up and are established when female fertility is just slightly more than the hermaphroditic fertility. The female only needs to make slightly more or better seeds than hermaphrodites since the mitochondrial genome is maternally inherited. Research done on plants has shown that hermaphroditic plants are in constant battles against organelle genes trying to kill their male parts. In over 140 plant species, these “male killer” genes have been observed. Male sterility genes cause plants to grow anthers that are stunted or withered and as a result, do not produce pollen. In most plants, there are nuclear fertility restoring genes that counteract the work of the male sterility genes, maintaining the hermaphroditic state of the plant. However, in some species of plants, the male sterility genes win the battle over the nuclear fertility restoring genes, and gynodioecy occurs. Maize farmers take advantage of gynodioecy to produce favorable hybrid maize seeds | Biology | https://en.wikipedia.org/wiki?curid=21378333 | Gynodioecy | 140,660 |
Gynodioecy The farmers deliberately make use of the gynodioecy that develops in the maize, resulting in a population of male-sterile and female-fertile individuals. They then introduce a new strain of male-sterile individuals and the breeders are able to collect the more favorable hybrid seeds. is a rare, but widely distributed sexual system in angiosperm species. is found in at least 81 different angiosperm families. Of all the angiosperms on Earth, less than 1% of them are gynodioecious species. One likely explanation for its rarity is due to its limited evolution. Since females are at a disadvantage when compared to hermaphrodites, they will never be able to evolve as quickly. In addition, gynodioecy is rare because the mechanism that favor females and cause gynodioecy in some populations only operate in some plant lineages, but not others. The reason for this variation in the rarity of gynodioecy stems from certain phenotypic traits or ecological factors that promote and favor the presence of female plants in a population. For example, a herbaceous growth form is much more highly favored in gynodioecious species of Lamiaceae as compared to woody lineages. Herbaceous growth form is also associated with a reduced pollen limitation and an increased self-fertilization. A reduced pollen limitation may decrease seed quantity and quality. Woody growth form Lamiaceae are more pollen-limited, and thus, produce less seeds and seeds of lower quality, thus favoring the female herbaceous growth form | Biology | https://en.wikipedia.org/wiki?curid=21378333 | Gynodioecy | 140,661 |
Gynodioecy is rare because some sexual systems are more evolutionary liable to change in certain lineages as compared to others. The maintenance of gynodioecy at first may seem like a mystery. Theoretically, hermaphrodites should have the evolutionary and reproductive advantage over females in a population because they naturally can produce more offspring. Hermaphrodites can transmit their genes through both pollen and ovules, whereas females can only transmit genes via ovules. Thus, in order for females to remain viable in a population, they would have to be twice as successful as hermaphrodites. It would appear that gynodioecy should not persist. In order for it to be maintained, the females need to have some sort of a reproductive advantage over the hermaphroditic population, known as female compensation or female advantage. Female advantage includes an increase in saved energy from not producing pollen and making seedlings of higher quality, since hermaphrodite seedlings are susceptible to homozygous deleterious alleles. Additional advantages include more flowers, higher fruit set, higher total seed production, heavier seeds, and better germination rates. The following species have been observed to exhibit a gynodioecious breeding system: | Biology | https://en.wikipedia.org/wiki?curid=21378333 | Gynodioecy | 140,662 |