Who discovered mitochondrial DNA?
1329361#2
The cytosolic, intermembrane space, compartment has a water content of 3.8 μl/mg protein, while the mitochondrial matrix 0.8 μl/mg protein. It is not known how mitochondria maintain osmotic balance across the inner mitochondrial membrane, although the membrane contains aquaporins that are believed to be conduits for regulated water transport. Mitochondrial matrix has a pH of about 7.8. Mitochondrial DNA was discovered by Nash and Margit in 1963. One to many double stranded mainly circular DNA is present in mitochondrial matrix. Mitochondrial DNA is 1% of total DNA of a cell. It is rich in Guanine and Cytosine content. Mitochondria of mammals have 55s ribosomes.
Mitochondrial matrix
89796#43
Mitochondrial DNA was discovered in the 1960s by Margit M. K. Nass and Sylvan Nass by electron microscopy as DNase-sensitive threads inside mitochondria, and by Ellen Haslbrunner, Hans Tuppy and Gottfried Schatz by biochemical assays on highly purified mitochondrial fractions.
Mitochondrial DNA
89796#7
The fact that mitochondrial DNA is maternally inherited enables genealogical researchers to trace maternal lineage far back in time. (Y-chromosomal DNA, paternally inherited, is used in an analogous way to determine the patrilineal history.) This is usually accomplished on human mitochondrial DNA by sequencing the hypervariable control regions (HVR1 or HVR2), and sometimes the complete molecule of the mitochondrial DNA, as a genealogical DNA test. HVR1, for example, consists of about 440 base pairs. These 440 base pairs are compared to the same regions of other individuals (either specific people or subjects in a database) to determine maternal lineage. Most often, the comparison is made with the revised Cambridge Reference Sequence. Vilà "et al." have published studies tracing the matrilineal descent of domestic dogs from wolves.
The concept of the Mitochondrial Eve is based on the same type of analysis, attempting to discover the origin of humanity by tracking the lineage back in time.
Mitochondrial DNA
3778551#4
Schatz identified a region of the yeast’s nuclear DNA that was associated with the mitochondria in 1964. Later, it was discovered that mutants without the ρ-factor had no mitochondrial DNA (called ρ isolates), or that they possessed a difference in density or amount of the mitochondrial (called ρ isolates). The use of electron microscopy to view the DNA in the mitochondrial matrix helped to verify the actuality of the mitochondrial genome.
Petite mutation
89796#10
Male mitochondrial DNA inheritance has been discovered in Plymouth Rock chickens. Evidence supports rare instances of male mitochondrial inheritance in some mammals as well. Specifically, documented occurrences exist for mice, where the male-inherited mitochondria were subsequently rejected. It has also been found in sheep, and in cloned cattle. Rare cases of male mitochondrial inheritance have been documented in humans. Although many of these cases involve cloned embryos or subsequent rejection of the paternal mitochondria, others document "in vivo" inheritance and persistence under lab conditions.
Mitochondrial DNA
19588#8
In 1967, it was discovered that mitochondria contained ribosomes. In 1968, methods were developed for mapping the mitochondrial genes, with the genetic and physical map of yeast mitochondrial DNA being completed in 1976.
Mitochondrion
38625611#3
Wallace is a pioneer in the study of mitochondrial DNA. Wallace and his colleagues introduced human mitochondrial genetics into the field of molecular genetics. In 1975, for the first time ever, Wallace could associate a genetic disorder with the mitochondrial DNA region (resistance to chloramphenicol) and in 1990 he described a mitochondrial DNA mutation as the cause of a particular form of myoclonic epilepsy. He has been instrumental in the study of the mitochondrial genome and has developed new methods for the analysis of mitochondrial DNA.
Douglas C. Wallace
160125#19
Spindle transfer, where the nuclear DNA is transferred to another healthy egg cell leaving the defective mitochondrial DNA behind, is a potential treatment procedure that has been successfully carried out on monkeys. Using a similar pronuclear transfer technique, researchers at Newcastle University led by Douglass Turnbull successfully transplanted healthy DNA in human eggs from women with mitochondrial disease into the eggs of women donors who were unaffected. In such cases, ethical questions have been raised regarding biological motherhood, since the child receives genes and gene regulatory molecules from two different women. Using genetic engineering in attempts to produce babies free of mitochondrial disease is controversial in some circles and raises important ethical issues. A male baby was born in Mexico in 2016 from a mother with Leigh syndrome using spindle transfer.
Mitochondrial disease
8564084#3
Mitochondria, as a major energy factory of the cell, was previously a free-living prokaryote that invades the eukaryotic cells by the endosymbiosis theory, which gained acceptance around the 1970s. Under this theory, symbiotic organelles gradually transferred their genes to the eukaryotic genome, implying that mtDNA was gradually integrated into the nuclear genome. Despite the metabolic alterations and functional adaptations in the host eukaryotes, circular mitochondrial DNA is contained within the organelles. Containing 37 genes, mitochondrial DNA has an essential role in the production of necessary compounds, such as required enzymes for the proper function of mitochondria. Specifically, it has been suggested that certain genes (such as the genes for cytochrome oxidase subunits I and II) within the organelle are necessary to regulate redox balance throughout membrane-associated electron transport chains. These parts of the mitochondrial genome have been reported to be the most frequently employed. Mitochondria is not the only location within which the cell mtDNA, mitochondrial DNA, can be found; sometimes transfer of mitochondrial DNA from organelles to the nucleus can occur; the evidence of such translocation has been seen through the comparison of mitochondrial DNA sequence with the genome sequence of the counterparts. The integration and recombination of cytoplasmic mtDNA into the nuclear DNA is called Nuclear Mitochondrial DNA, which is abbreviated as NUMT.
The possible presence of organelle DNA inside the nuclear genome was suggested after finding of homologous structure to the mitochondrial DNA, which was shortly after the discovery of the presence of an independent DNA within the organelles in 1967. This topic stayed untouched until the 1980s. Initial evidence that DNA could move among cell compartments came when fragments of chloroplast DNA were found in the maize mitochondrial genome with the help of cross-hybridization, between chloroplast and mitochondrial DNA, and physical mapping of homologous regions. After this initial observation, Ellis coined the name "promiscuous DNA" in order to signify the transfer of DNA intracellularly from one organelle to the other and is the presence of organelle DNA in multiple cellular compartments. This is not only an important discovery on its own, but is also highly informative and helpful for understanding the evolutionary process and the time period different occurrence might take place. The searching for mtDNA in nuclear DNA continued until 1994 when the recent remarkable transposition of 7.9 kb of a typically 17.0-kb mitochondrial genome to a specific nuclear chromosomal position in the domestic cat was reported. This is the time that NUMT was coined to designate the large stretches of mitochondrial DNA in the genome.
Up to now, the whole genomes of many eukaryotes, both vertebrate, and invertebrate, have been sequenced and NUMT was observed in the nuclear genome of various organisms, including yeast, "Podospora", sea urchin, locust, honey bee, "Tribolium", rat, maize, rice, and primates. In Plasmodium, "Anopheles gambiae", and "Aedes aegypti" mosquitoes NUMT can barely be detected. In contrast, the conserved fragments of NUMT have now few were identified in genome data for "Ciona intestinalis", "Neurospora crassa", "Schizosaccharomyces pombe", "Caenorhabditis elegans", "Drosophila melanogaster", and "Rattus norvegicus". Antunes and Ramos were found the presence of NUMT in the fish genome for the first time in 2005 using of BLASTN, MAFFT, very vigorous genome mappings, and phylogenic analysis. Across the animal kingdom, "Apis mellifera", from phylum "Arthropoda", and "Hydra magnipapillata", from phylum "Cnidaria", are respectively the first and second animals with the highest ratio of NUMTs to the total size of the nuclear genome while "Monodelphis Domestica", or Gray short-tailed opossum, is the record holder for NUMT frequency among vertebrates. Similar to animals, NUMTs are abundant in the plants and the longest NUMT fragment known so far, a 620-kb partially duplicated insertion of the 367-kb mtDNA of "Arabidopsis thaliana", was reported.
NUMT
89796#1
In humans, the 16,569 base pairs of mitochondrial DNA encode for only 37 genes. Human mitochondrial DNA was the first significant part of the human genome to be sequenced. In most species, including humans, mtDNA is usually inherited solely from the mother. However, in exceptional cases, human babies sometimes inherit mtDNA from both their fathers and their mothers resulting in mtDNA heteroplasmy.
Mitochondrial DNA