关键词: 绵羊; 瘦素受体基因; 单核苷酸多态性; 系统发育

Abstract: In order to lay the foundation for further study on relationship between polymorphisms of LEPR and growth traits in sheep, using DNA and RNA samples from a population crossed between Merrino and Awassi sheep, parts of ovine LEPR cDNA and intron 7 were sequenced in 4 ewes in an attempt to find polymorphisms, and DNA from 229 samples were genotyped by PCR-RFLP at two mutation loci. The 2608 bp of LEPR cDNA included complete exon 2 to exon 16 and partial sequence of exon 1 and exon 17, and the whole length of LEPR intron 7 was 160 bp. 5 point mutations were found, two in exon 2 (T240C and A279G ), A1683G and T2373C were in exon 10 and exon 14 respectively, at the same time, a A to G mutation was found in intron 7 (1285+A73G). They all didn’t cause amino acid substitution. Frequencies for allele A at A279G and A1683G were 0.415 and 0.467,respectively. However, the latter was in Hardy-Weinberg disequilibrium, and GG and AA were the main haplotypes in this sheep population. The similarity scores of LEPR cDNA or intron 7 were high among species, though the former were higher, and the phylogenetic tree based on LEPR mRNA was more accurate with higher reliability value than based on LEPR intron 7, which may be caused mainly by the length of intron 7. These results indicated that ovine LEPR was highly conserved, and transition was the main mutation way, in addition, A279G and A1683G were mutational hotspots in LEPR gene.

Key words: sheep; leptin receptor gene (LEPR); single nucleotide polymorphism (SNP); phylogenesis