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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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J. Evans A.W Ford-Hutchinson B. Fitzsimmons J. Rokach 《Prostaglandins & other lipid mediators》1984,28(3)
Chemically synthesized 8(S)-dihydroxy-5, 11-cis-9, 13-transeicosatetraenoic acid and 8(R), 15(S)-dihydroxy-5, 11-cis-9, 13-transeicosatetraenoic acid were inactive, in comparison to leukotriene B4, in a human polymorphonuclear leukocyte chemokinetic assay and a rat polymorphonuclear leukocyte aggregation assay. 相似文献
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Four cohorts of 40 subjects each were randomly assigned to 1 of 10 treatment conditions utilizing EMG feedback, cognitive monitoring training, systematic desensitization, high expectancy discussion group, or waiting list controls either in isolation or in various combinations. A three-way ANOVA for repeated measures indicated that significant anxiety reductions were experienced in all noncontrol treatment conditions. Treatment groups employing EMG feedback demonstrated significantly greater anxiety decrements on Cattell's IPAT Self-Analysis Form, and baseline frontalis EMG. Adding desensitization or cognitive monitoring to EMG feedback did not produce a more powerful effect than using EMG feedback alone. Sex and age differences were also observed. Some implications are discussed.This research was supported in part by a grant from the Medical Services Research Foundation of Alberta. 相似文献
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Fiona C Buchanan Carolyn J Fitzsimmons Andrew G Van Kessel Tracey D Thue Dianne C Winkelman-Sim Sheila M Schmutz 《遗传、选种与进化》2002,34(1):105-116
Previously, we have shown that alleles of the BM1500 microsatellite, located 3.6 kb downstream of the leptin gene in cattle, were associated with carcass fat measures in a population of 154 unrelated beef bulls. Subsequently, a cytosine (C) to thymine (T) transition that encoded an amino acid change of an arginine to a cysteine was identified in exon 2 of the leptin gene. A PCR-RFLP was designed and allele frequencies in four beef breeds were correlated with levels of carcass fat. The T allele was associated with fatter carcasses and the C allele with leaner carcasses. The frequencies of the SNP alleles among breeds indicated that British breeds have a higher frequency of the T allele whereas the continental breeds have a higher occurrence of the C allele. A ribonuclease protection assay was developed to quantify leptin mRNA in a separate group of animals selected by genotype. Animals homozygous for thymine expressed higher levels of leptin mRNA. This may suggest that the T allele, which adds an extra cysteine to the protein, imparts a partial loss of biological function and hence could be the causative mutation. 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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L G Letts M Cirino P Yusko B Fitzsimmons A W Ford-Hutchinson J Rokach 《Prostaglandins》1985,29(6):1049-1062
The actions of leukotrienes (LT's) C4, D4, E4 and F4 have been investigated in the perfused hind-limb of the anesthetized pig. In the blood perfused hind limb LTC4, D4 and E4 increased the perfusion pressure in a dose-dependent fashion whereas LTF4 decreased perfusion pressure. In the Tyrode perfused hind limb all LT's increased perfusion pressure (rank order potency LTC4 = LTD4 much greater than LTF4). The actions of LTF4 were not affected by a wide variety of pharmacological treatments, including indomethacin, methysergide and FPL-55712. The LT's aggregated porcine platelets (rank order potency LTC4 greater than LTF4 greater than LTD4) and induced the release of a platelet-derived vasodilatory mediator. The results provide pharmacological evidence of specific leukotriene receptors in vivo and that leukotrienes can independently modulate blood flow. These data suggest that important interactions may occur between platelets, the arachidonate lipoxygenase products and platelet-derived substances in response to inflammatory stimuli in the cardiovascular system. 相似文献
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