[Relative quantification of mRNA transcription of Cry1 in different tissues of sheep in oestrous cycle by real-time quantitative PCR].

Studies have shown that clock gene Cry1 may have important roles in the endocrine process of seasonal reproduction in mammals. In this study, Duolang sheep (non-seasonal reproduction sheep breed) and Chinese Merino (seasonal reproduction sheep breed) were used to determine the expression change of Cry1 in hypothalamus-pituitary-ovary axis in different stage of estrous cycle by quantitative real-time PCR. The results showed that the Cry1 mRNA was expressed in all tested tissues, in which the expression levels in pineal gland and thyroid gland were higher than in other tissues. As far as different sheep breeds were concerned, the tissue expression profiles of Cry1 at different stage of estrous cycle were broadly similar. Besides hypothalamus, the expression levels of Cry1 in ovary, uterus, pineal gland, pituitary gland, and thyroid gland were all reached to peak in proestrus. The differences of expression change extent for Cry1 in vary, uterus, pineal gland, and pituitary gland in proestrus and oestrus were significant between different sheep breeds. The results suggested that Cry1 may play roles in switching on the estrus and seasonal reproduction.

[Detection and analysis of polymorphisms of 59571364 and 59912586 loci on X chromosome in fat-tail and thin-tail sheep flocks].

In order to analyze the correlation of tail fat deposition and two SNP loci on Ovis arise chromosome X and provide a theoretical basis for using molecular assisted selection technology in further low-fat sheep breeding, the breeds with extreme differences in tail types (Altay, Small Tail Han Sheep, Hu, Chinese Merino and Suffolk) were used to detect the polymorphisms of two SNP loci on X chromosome and the haplotypes with PCR-RFLP method. The results showed that the TT genotype at 59571364 locus and GG genotype at 59912586 locus were preponderant genotypes in thin-tailed Chinese Merino and Suffolk sheep flocks, while the percentage of the two genotypes in fat-tailed (fat-rmup) Altay and Hu flocks is less than 2%. Haplotype analysis showed that CA haplotype is the main haplotype, the percentage of CA is up to 55%, and the percentage of CA and TA haplotypes together was 88.33% in Altay sheep flock. These results suggest that there are great differences in the SNP distribution of the 59571364 and 59912586 loci among different tail-typed sheep flocks, which can be used as molecular markers in high or low fat sheep breeding.

[Correlation analysis between polymorphism of the 59383635th locus on X chromosome and fat-tail trait in sheep].

Fat tail or fat rump is one of essential traits for surviving in harsh environments, and the mechanism of fat deposition and its inheritable characters in sheep are still unclear. Therefore, the 59383635th locus on X chromosome in our unpublished chip data was chosen as candidate SNP, PCR-SSCP method was used to detect genotypes in five sheep breeds which have extreme differences in tail types (Altay, Small Tail Han Sheep, Hu, Chinese Merino and Suffolk), and the mathematical model was employed to analyze the correlation between the polymorphism and the trait of fat tail or fat rump. The results in this study showed that the high frequency of allele T exists in Altay flock, and the frequency of allele C appears to be particularly high in the thin tail sheep breeds. The result of mathematical model showed that the ratio of T/C increased exponentially with the increase of phenotype score. These results suggest that there is a big difference in the SNP distribution between fat tail (rump) and thin tail sheep populations, and the SNP can be used as an ideal molecular marker in high-fat or low-fat sheep breeding. However, the biological function of the SNP remains to be further studied.

[The gene ontology and electro localization of ovine skin derived EST-SSR markers].

Abstract: In order to study the potential gene function of ovine EST-SSR markers, nine original EST of Ovine Skin Derived polymorphic EST-SSR loci, which were developed in an early study by our lab, were ontology annotated and Electro localized. The results revealed that the original ESTs of the six loci had high homology with known genes and three of them probably played an important role in wool traits. Compared with its cDNA library, 8 loci were located on chromosomes of cattle. The homology of chromosomes between cattle and sheep was estimated based on the similarity coefficients calculated by positioning markers. Additionally, NJ clustering tree was establishedto serve for electro localization of ovine EST-SSR markers. Finally, 8 EST-SSR markers were successfully positioned on ovine chromosomes. The results from this study not only provide references for further studies on genetic mapping, in silico cloning of key genes for wool traits, but also are helpful to the researchs of chromosome evolution in animal.