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Tibet pig is a unique native breed in the plateau of China, which has good adaptation to the harsh climate of high land and resistance to diseases and crude feeding. However, its reproductive rate is low. The objectives of this study were to search for the polymorphisms of estrogen receptor (ESR), follicle-stimulating hormone (FSHb), prolactin receptor (PRLR), and retinol binding protein 4 (RBP4) in Tibet pig and to analyze the effects of these variants and their combination genotypes on reproductive traits. The results showed that the effects of FSHb, ESR, and PRLR genes were significant in the Tibet pig population, and the effective genotypes of the three genes for reproductive traits were BB, BB, and AA, respectively. There were two genotypes for RBP4 gene in Tibet pig, which did not have significant effect on the reproductive traits. The optical genotype of FSHb-ESR-PRLR is BB-BB-AA, which is more effective on reproductive traits than any single gene in Tibet pig.

The inducible nitric-oxide synthase (iNOS) can be induced by hypoxia to produce NO, which regulates blood flow and improves oxygen delivery to tissues. In present study, SNPs in coding and 5'-flanking regions of iNOS gene were examined in Tibetan chicken and lowland chicken using sequence and PCR-RFLP methods, and the quantitive express of mRNA of iNOS and the enzyme activity were measured in chorioallantoic membrane of chick embryo that was incubated under hypoxic and normal conditions. The results showed that a special SNP (-870C-->T)was found in 5'-flanking region of iNOS gene. Tibetan chicken has higher frequencies in mutation allele T than lowland chicken. In hypoxic incubation, the mRNA expression of iNOS and enzyme activity were higher in Tibetan chicken than that in Dwarf chicken. It was concluded that the mutation of iNOS and hypoxic increase of its expression were important base for adaptability to hypoxia in Tibetan chicken.

Tibet pig is a special Chinese indigenous pig breed, which could survive in high-altitude areas of Tibet. In the present study, the genotypes of ESR, FSHbeta, and PRLR gene, the three known major genes of reproductive traits, were identified in 202 Tibet pig individuals. The results showed that the predominant genotypes of ESR, FSHbeta, and PRLR gene were BB, AB and AA, respectively. The genotype frequencies of the three genes were in Hardy-Weinberg equilibrium. The frequencies of desired alleles of the three genes were higher than those of other alleles, which indicated that Tibet pig had a good potential for improving reproductive traits.