44836362
A defective retrovirus particle (SE21Q1b) packages and reverse transcribes cellular RNA, utilizing tRNA-like primers.
Linial and co-workers described a quail cell line, SE21Q1b, transformed by a single provirus of Rous sarcoma virus that is defective in virus assembly, in as much as the virus particles produced, SE21, contain cellular rather than viral RNA. In other respects these particles are normal, and the amount of endogenous DNA synthesis by disrupted virus particles is comparable to that of normal virus. We now report that endogenous DNA synthesis by SE21 virions uses RNA primers of the same size as tRNA species and that about 17% of these are bound to polyadenylate-containing RNA templates. Previous studies have shown that with wild-type Rous sarcoma virus, DNA synthesis is exclusively initiated on a tRNATrp species base paired to a specific location on the viral RNA. In contrast, we interpreted our data with SE21 as evidence that many different tRNA-primed initiations occurred, that predominantly species other than tRNATrp were used, and that the base pairing between template and primer RNAs included significant nucleotide mismatching. A subpopulation of the DNA synthesized by SE21 virions from tRNA-like primers was both initiated and terminated at discrete locations. These species are therefore analogous to the strong-stop DNA synthesized by wild-type virus.
27724235
Avian RNA tumor virus DNA before and after integration into the host genome.
33501684
Tumor virus ribonucleic acid directed deoxyribonucleic acid synthesis: nucleotide sequence at the 5' terminus of nascent deoxyribonucleic acid.
11606238
Hepatitis delta virus.
Hepatitis delta virus (HDV) is a sub-viral agent that is dependent for its life cycle on hepatitis B virus (HBV). The help it obtains from HBV is limited to the sharing of envelope proteins. These proteins are needed to facilitate the assembly of the HDV genome into new virus particles, and in turn, to allow the attachment and entry of HDV into new host cells. In other respects, the replication of the small single-stranded circular RNA genome of HDV is independent of HBV. HDV genome replication produces two forms of a RNA-binding protein known as the long and small delta antigens (Ag). All other proteins needed for HDV genome replication, especially the RNA-directed RNA polymerase activity, are provided by the host cell. This mini-review article is a mixture of personal perspective and speculations about the future of HDV research. It starts with a brief overview of HDV and its replication, notes some of the major unresolved questions, and directs the interested reader to more detailed reviews.
12985098
A note on the incorporation of amino acids by hamster embryo cells in monolayer culture.
28296194
Retrovirus Genome Replication: Priming Specificities of Plus-Strand DNA Synthesis
SUMMARY The retroviral reverse transcriptase is a multifunctional protein. Not only does it contain both RNA- and DNA-directed DNA synthesis activities but also it contains an endonuclease activity necessary for the integration of viral RNA and a RNase H. This latter activity can reduce to oligoribonucleotides viral RNA that has been reverse transcribed into minus-strand DNA. However, during avian retrovirus genome replication it does this in a highly specific manner so as to generate a specific 12-base primer for plus-strand DNA synthesis. Even though many other oligoribonucleotides are also made there is an efficient selection of the specific primer followed by its efficient utilization in plus-strand DNA synthesis, and subsequent removal. We have used a reconstructed system to gain an understanding of the factors that contribute towards these observed specificities.
13643640
Driving anxiety and fear in young older adults in New Zealand.
BACKGROUND
driving anxiety and fear can have a marked impact on mobility and independence, although there is no data on the prevalence of this problem, and specific information about the rate of driving anxiety and fear in older adults is unknown.


METHODS
the present study examines the prevalence of self-reported driving anxiety and fear in a sample of 2,491 adults aged 55-72 from a longitudinal survey of health and ageing in New Zealand.


RESULTS
most of the sample (90%) described themselves as drivers who drove daily or weekly. Around 70% of the sample reported no driving anxiety or fear, yet 17-20% endorsed a mild and 4-6% rated a moderate to severe level of driving anxiety and fear. Women reported higher levels of anxiety and fear about driving than men, but there were no age differences. Those who reported some level of driving anxiety engaged various alternative modes of transport, and a small number (2.4%) reported that their driving anxiety had affected their usual activities or work for at least a day in the previous month. Duration of driving anxiety was highly variable, from relatively recent onset to being present for much of some participants' lifetimes.


CONCLUSION
driving anxiety and fear may be a significant problem for some young older adults that is likely to affect their independence and mobility. Further research to clarify the content and nature of driving anxiety, pathways to driving anxiety and the effect of factors associated with ageing on driving anxiety is needed in order to better understand this experience for older adults and develop effective interventions.
13468480
ESPERR: learning strong and weak signals in genomic sequence alignments to identify functional elements.
Genomic sequence signals - such as base composition, presence of particular motifs, or evolutionary constraint - have been used effectively to identify functional elements. However, approaches based only on specific signals known to correlate with function can be quite limiting. When training data are available, application of computational learning algorithms to multispecies alignments has the potential to capture broader and more informative sequence and evolutionary patterns that better characterize a class of elements. However, effective exploitation of patterns in multispecies alignments is impeded by the vast number of possible alignment columns and by a limited understanding of which particular strings of columns may characterize a given class. We have developed a computational method, called ESPERR (evolutionary and sequence pattern extraction through reduced representations), which uses training examples to learn encodings of multispecies alignments into reduced forms tailored for the prediction of chosen classes of functional elements. ESPERR produces a greatly improved Regulatory Potential score, which can discriminate regulatory regions from neutral sites with excellent accuracy ( approximately 94%). This score captures strong signals (GC content and conservation), as well as subtler signals (with small contributions from many different alignment patterns) that characterize the regulatory elements in our training set. ESPERR is also effective for predicting other classes of functional elements, as we show for DNaseI hypersensitive sites and highly conserved regions with developmental enhancer activity. Our software, training data, and genome-wide predictions are available from our Web site (http://www.bx.psu.edu/projects/esperr).
5250005
Common genetic and nonshared environmental factors contribute to the association between socioemotional dispositions and the externalizing factor in children.
BACKGROUND
Childhood behavioral disorders including conduct disorder (CD), oppositional defiant disorder (ODD), and attention-deficit/hyperactivity disorder (ADHD) often co-occur. Prior twin research shows that common sets of genetic and environmental factors are associated with these various disorders and they form a latent factor called Externalizing. The developmental propensity model posits that CD develops in part from socioemotional dispositions of prosociality, negative emotionality, and daring; and recent research has supported the expected genetic and environmental associations between these dispositions and CD. This study examined the developmental propensity model in relation to the broader Externalizing factor that represents the covariance among behavior disorders in children.


METHODS
Parents of 686 six- to twelve-year-old twin pairs rated them on symptoms of CD, ADHD, and ODD using the disruptive behavior disorder scale and on prosociality, negative emotionality, and daring using the child and adolescent dispositions scale. A latent factor multivariate Cholesky model was used with each disposition latent factor comprised of respective questionnaire items and the Externalizing factor comprised of symptom dimensions of CD, ADHD inattention, ADHD hyperactivity/impulsivity, and ODD.


RESULTS
Results supported the hypothesis that the socioemotional dispositions and the Externalizing factor have genetic factors in common, but there was not a single genetic factor associated with all of the constructs. As expected, nonshared environment factors were shared by the dispositions and externalizing factor but, again, no single nonshared environmental factor was common to all constructs. A shared environmental factor was associated with both negative emotionality and externalizing.


CONCLUSIONS
The developmental propensity model was supported and appears to extend to the broader externalizing spectrum of childhood disorders. Socioemotional dispositions of prosociality, negative emotionality, and (to a lesser extent) daring may contribute to the covariation among behavioral disorders and perhaps to their comorbid expression through common sets of primarily genetic but also environmental factors.
6962773
Heritability of Wisconsin Card Sorting Test (WCST) and Stroop Color-Word Test performance in normal individuals: implications for the search for endophenotypes.
A surge in the search for endophenotypes for psychiatric disorders has occurred in the past several years. An important criterion of an endophenotype is that it is heritable. Two of the most widely used executive cognitive functioning measures are the Wisconsin Card Sorting Test (WCST) and the Stroop Color-Word Test. Each has been considered as a possible endophenotype. However, research on the heritability of each of these measures is sparse, and in the case of the WCST, mixed. As part of a pilot twin study examining cognitive functioning and personality in adults, the WCST and the Stroop were administered to 80 monozygotic and 29 dizygotic twin pairs screened for absence of neurological disease and head injury. Results replicated and extended previous findings for moderate heritability of Stroop performance. However, the WCST showed little evidence of genetic influence, suggesting that it might not meet one of the criteria for an endophenotype.
45640355
A behavioral genetic analysis of the relationship between the socialization scale and self-reported delinquency.
This investigation examined the genetic (A), and shared (C) and nonshared (E) environmental variance contributions to the relationship of self-reported delinquency (as measured by the "Delinquent Behavior Inventory" [DBI; Gibson, 1967]) to the Socialization (So) scale of the California Psychological Inventory using univariate and bivariate structural equation models. The scales were administered to 222 male (145 monozygotic; 77 dizygotic) and 159 female (107 monozygotic; 52 dizygotic) 16- to 18-year-old same-sex twin pairs. Principal components analysis with varimax rotation revealed three interpretable So factors representing family/home environment, self-concept, and behavioral control. Univariate modeling suggested sex differences in etiological influences associated with individual differences in most scales. The bivariate ACE model fit the data, suggesting that the covariance between the So scale and self-reported delinquency owes in part to shared etiological factors.