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1.
A method was developed to optimize simultaneous selection for a quantitative trait with a known QTL within a male and a female line to maximize crossbred performance from a two-way cross. Strategies to maximize cumulative discounted response in crossbred performance over ten generations were derived by optimizing weights in an index of a QTL and phenotype. Strategies were compared to selection on purebred phenotype. Extra responses were limited for QTL with additive and partial dominance effects, but substantial for QTL with over-dominance, for which optimal QTL selection resulted in differential selection in male and female lines to increase the frequency of heterozygotes and polygenic responses. For over-dominant QTL, maximization of crossbred performance one generation at a time resulted in similar responses as optimization across all generations and simultaneous optimal selection in a male and female line resulted in greater response than optimal selection within a single line without crossbreeding. Results show that strategic use of information on over-dominant QTL can enhance crossbred performance without crossbred testing. 相似文献
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Effect of postnatal development on calcium currents and slow charge movement in mammalian skeletal muscle 总被引:16,自引:3,他引:13 下载免费PDF全文
Single- (whole-cell patch) and two-electrode voltage-clamp techniques were used to measure transient (Ifast) and sustained (Islow) calcium currents, linear capacitance, and slow, voltage-dependent charge movements in freshly dissociated fibers of the flexor digitorum brevis (FDB) muscle of rats of various postnatal ages. Peak Ifast was largest in FDB fibers of neonatal (1-5 d) rats, having a magnitude in 10 mM external Ca of 1.4 +/- 0.9 pA/pF (mean +/- SD; current normalized by linear fiber capacitance). Peak Ifast was smaller in FDB fibers of older animals, and by approximately 3 wk postnatal, it was so small as to be unmeasurable. By contrast, the magnitudes of Islow and charge movement increased substantially during postnatal development. Peak Islow was 3.6 +/- 2.5 pA/pF in FDB fibers of 1-5-d rats and increased to 16.4 +/- 6.5 pA/pF in 45-50-d-old rats; for these same two age groups, Qmax, the total mobile charge measurable as charge movement, was 6.0 +/- 1.7 and 23.8 +/- 4.0 nC/microF, respectively. As both Islow and charge movement are thought to arise in the transverse-tubular system, linear capacitance normalized by the area of fiber surface was determined as an indirect measure of the membrane area of the t-system relative to that of the fiber surface. This parameter increased from 1.5 +/- 0.2 microF/cm2 in 2-d fibers to 2.9 +/- 0.4 microF/cm2 in 44-d fibers. The increases in peak Islow, Qmax, and normalized linear capacitance all had similar time courses. Although the function of Islow is unknown, the substantial postnatal increase in its magnitude suggests that it plays an important role in the physiology of skeletal muscle. 相似文献
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A. E. Retief J. A. Van Zyl R. Menkveld M. F. Fox G. M. Kotzè J. Brusnický 《Human genetics》1984,66(2-3):162-164
Summary Chromosome studies were performed on 106 men with azoospermia and 390 men with oligozoospermia (consistant sperm count below 10 million/ml). Constitutional chromosome abnormalities were found in 14.1% of the azoospermia group and in 5.1% of the oligozoospermia group. An overall incidence of 7.1% constitutional abnormalities indicates that this criterion of selection may be advisable for routine chromosome analysis of infertile men. A reduction of 25% in the workload increases the yield of chromosome abnormalities in the group of infertile men to 10–14 times above that expected in the normal population. 相似文献
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B van der Walt B Kotzé P P van Jaarsveld H Edelhoch 《The Journal of biological chemistry》1978,253(6):1853-1858
Bovine thyroglobulin was extracted from unfrozen glands, purified by sucrose gradient centrifugation, and fractionated into a narrow range in iodine content by RbCl isopycnic centrifugation. The subunit composition of these preparations was studied by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. The extent of dissociation of 19 S into 12 S half-molecules followed the known relationship with iodine, i.e. decreased dissociability of 19 S with increased iodine content. The undissociated 19 S band always consisted of three closely spaced, equidistant bands. Reduction of the disulfide bonds of thyroglobulin by mercaptoethanol in SDS solution resulted in the formation of two major and one minor components (S, F, and A). The concentration of A was always less than 10% of the total. The ratio of S to F was, however, about equal in thyroglobulin preparations which ranged in iodine content from 0.2 to 1%. The final ratios were obtained before all the disulfides were reduced. The relative mobilitis of S, F, and A, decreased with increasing extent of reduction. Fully reduced S and F, but not A, migrated slower than unreduced 12 S. The three reduced alkylated polypeptides were purified by preparative SDS-polyacrylamide gel electrophoresis and their molecular weights were determined by sedimentation equilibrium in 8 M urea. Their Mw and Mz values agreed closely with that of the unreduced 12 S half-molecule subunit, thus indicating that reduction of the disulfide bonds changes the shape but not the molecular weights of the subunits. 相似文献
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For a finite locus model, Markov chain Monte Carlo (MCMC) methods can be used to estimate the conditional mean of genotypic values given phenotypes, which is also known as the best predictor (BP). When computationally feasible, this type of genetic prediction provides an elegant solution to the problem of genetic evaluation under non-additive inheritance, especially for crossbred data. Successful application of MCMC methods for genetic evaluation using finite locus models depends, among other factors, on the number of loci assumed in the model. The effect of the assumed number of loci on evaluations obtained by BP was investigated using data simulated with about 100 loci. For several small pedigrees, genetic evaluations obtained by best linear prediction (BLP) were compared to genetic evaluations obtained by BP. For BLP evaluation, used here as the standard of comparison, only the first and second moments of the joint distribution of the genotypic and phenotypic values must be known. These moments were calculated from the gene frequencies and genotypic effects used in the simulation model. BP evaluation requires the complete distribution to be known. For each model used for BP evaluation, the gene frequencies and genotypic effects, which completely specify the required distribution, were derived such that the genotypic mean, the additive variance, and the dominance variance were the same as in the simulation model. For lowly heritable traits, evaluations obtained by BP under models with up to three loci closely matched the evaluations obtained by BLP for both purebred and crossbred data. For highly heritable traits, models with up to six loci were needed to match the evaluations obtained by BLP. 相似文献
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