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101.
102.
Fabbro T Davison AC Steinger T 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2007,115(7):933-944
Many quantitative genetic statistics are functions of variance components, for which a large number of replicates is needed
for precise estimates and reliable measures of uncertainty, on which sound interpretation depends. Moreover, in large experiments
the deaths of some individuals can occur, so methods for analysing such data need to be robust to missing values. We show
how confidence intervals for narrow-sense heritability can be calculated in a nested full-sib/half-sib breeding design (males
crossed with several females) in the presence of missing values. Simulations indicate that the method provides accurate results,
and that estimator uncertainty is lowest for sampling designs with many males relative to the number of females per male,
and with more females per male than progenies per female. Missing data generally had little influence on estimator accuracy,
thus suggesting that the overall number of observations should be increased even if this results in unbalanced data. We also
suggest the use of parametrically simulated data for prior investigation of the accuracy of planned experiments. Together
with the proposed confidence intervals an informed decision on the optimal sampling design is possible, which allows efficient
allocation of resources. 相似文献
103.
Kovacheva VP Mellott TJ Davison JM Wagner N Lopez-Coviella I Schnitzler AC Blusztajn JK 《The Journal of biological chemistry》2007,282(43):31777-31788
During gestation there is a high demand for the essential nutrient choline. Adult rats supplemented with choline during embryonic days (E) 11-17 have improved memory performance and do not exhibit age-related memory decline, whereas prenatally choline-deficient animals have memory deficits. Choline, via betaine, provides methyl groups for the production of S-adenosylmethionine, a substrate of DNA methyltransferases (DNMTs). We describe an apparently adaptive epigenomic response to varied gestational choline supply in rat fetal liver and brain. S-Adenosylmethionine levels increased in both organs of E17 fetuses whose mothers consumed a choline-supplemented diet. Surprisingly, global DNA methylation increased in choline-deficient animals, and this was accompanied by overexpression of Dnmt1 mRNA. Previous studies showed that the prenatal choline supply affects the expression of multiple genes, including insulin-like growth factor 2 (Igf2), whose expression is regulated in a DNA methylation-dependent manner. The differentially methylated region 2 of Igf2 was hypermethylated in the liver of E17 choline-deficient fetuses, and this as well as Igf2 mRNA levels correlated with the expression of Dnmt1 and with hypomethylation of a regulatory CpG within the Dnmt1 locus. Moreover, mRNA expression of brain and liver Dnmt3a and methyl CpG-binding domain 2 (Mbd2) protein as well as cerebral Dnmt3l was inversely correlated to the intake of choline. Thus, choline deficiency modulates fetal DNA methylation machinery in a complex fashion that includes hypomethylation of the regulatory CpGs within the Dnmt1 gene, leading to its overexpression and the resultant increased global and gene-specific (e.g. Igf2) DNA methylation. These epigenomic responses to gestational choline supply may initiate the long term developmental changes observed in rats exposed to varied choline intake in utero. 相似文献
104.
Background
The composition of the individual eukaryote's genome and its variation within a species remain poorly defined. Even for a sequenced genome such as that of the model plant Arabidopsis thaliana accession Col-0, the large arrays of heterochromatic repeats are incompletely sequenced, with gaps of uncertain size persisting in them. 相似文献105.
John Davison Timothy J. Roper Charles J. Wilson Matthew J. Heydon Richard J. Delahay 《European Journal of Wildlife Research》2011,57(1):67-76
Examples from a variety of taxa demonstrate that under certain circumstances, the exclusion or translocation of ‘problem’
animals is ineffective in resolving human–wildlife conflicts and may even elicit new problems elsewhere. Damage caused by
badger setts (burrows) is an important source of human–wildlife conflict in the UK and is commonly managed by excluding badgers
from all or part of problem setts. We used records of licences issued for the management of such problems and a novel statistical
approach to assess spatiotemporal associations between problem cases in England from 2002 to 2005. We predicted that management
at urban badgers' setts, and particularly exclusion of badgers from urban main setts, would give rise to subsequent problems
at focal setts and in neighbouring areas. Frequencies of problems occurring at individual setts were similar in urban and
rural areas. In areas neighbouring setts subjected to management action, the background frequency of problems was higher in
urban than in rural areas, reflecting the occurrence of problems at a higher proportion of urban setts. The frequency of new
cases arising at or in the vicinity of managed setts within a critical time period after management action was not significantly
different from the background frequency of problems for any combination of land use, sett type and management approach. This
finding suggests that the measures currently employed for managing problem setts do not importantly increase the likelihood
of problems reoccurring in the same location or emerging nearby. 相似文献
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109.
Limitations in the use of [3H]thymidine incorporation into DNA as an indicator of epidermal keratinocyte proliferation in vitro 总被引:2,自引:0,他引:2
The validity of using the incorporation of [3H]thymidine into DNA as an indicator of epidermal keratinocyte proliferation in vitro has been investigated. Other parameters of cell proliferation, direct count of cell number and measurement of DNA content, consistently fail to correlate with changes in [3H]thymidine incorporation into DNA in primary and first passage cultures of rabbit and human epidermal keratinocytes. Maximum incorporation of [3H]thymidine precedes the active growth period by three days. Incorporation declines markedly during the proliferative period. Thymidine kinase activity decreases during the proliferative growth phase. Incorporation of another pyrimidine nucleotide precursor, [14C]aspartic acid, suggests that in epidermal keratinocytes in vitro the extent of utilization of the salvage and the de novo pathways may be inversely related. In such cases [3H]thymidine incorporation into TCA precipitable material fails to reflect accurately cell proliferation. 相似文献
110.
Davison HR Solano DM Phuan PW Verkman AS Kurth MJ 《Bioorganic & medicinal chemistry letters》2012,22(4):1602-1605
(19)F-modified bithiazole correctors and phenylglycine potentiators of the ΔF508-CFTR chloride channel were synthesized and their function assayed in cells expressing human ΔF508-CFTR and a halide-sensitive fluorescent protein. Fluorine was incorporated into each scaffold using prosthetic groups for future biodistribution imaging studies using positron emission tomography (PET). The ΔF508-CFTR corrector and potentiator potencies of the fluorinated analogs were comparable to or better than those of the original compounds. 相似文献