Single Nucleotide Polymorphism (SNP), CDNA Cloning And Tissue Expression Of GH, IGF-Ⅰ,and IGF-Ⅱ Genes In Lezhi Black Goat

It is a very important approach to conserve the improved goat breeds and to develop goat production in our country through understanding genetic mechanism of prolificacy and increasing fertility of goats. Polymorphism of GH, IGF-Ⅰand IGF-Ⅱgenes and their relationships with prolificacy of Lezhi Black goat were analyzed in this study. In addition, cloning and mRNA expression levels of GH, IGF-Ⅰand IGF-Ⅱgenes were carried out in Lezhi Black Goat and Tibetan Goat in order to understand prolific mechanism of Lezhi Black Goat.(1) Polymorphism of GH, IGF-Ⅰand IGF-Ⅱgenes and their relationships with prolificacy. Blood were sampled from 157 Lezhi Black Goat which have litter size records. The primers were designed for GH, IGF-Ⅰand IGF-Ⅱ5'flanking region and exon sequences to detect the polymorphic loci associated with the litter size. The result shows that, the 5'flanking regions and other exons except 1st exon of GH revealed single nucleotide mutation. Only the 2nd exon of IGF-Ⅰsingle nucleotide mutation was detected while there were no single nucleotide mutation site existed in IGF-Ⅱ. The result of statistic analysis showed that the single mutation site of GH and IGF-Ⅰdoes not affect litter size of Lezhi black goats (P > 0.05).(2) Cloning and sequence analysis of GH, IGF-Ⅰand IGF-Ⅱgenes. The complete CDS of GH, IGF-Ⅰand IGF-Ⅱgenes of Lezhi Black Goat and Tibetan Goat were cloned by RT-PCR. The lengths were 654 bp, 465 bp and 540 bp respectively, encoding 217, 154, and 179 amino acids, respectively. Nucleotide and amino acid sequences were compared. The results showed that there was one different nucleotide between GH gene of Lezhi Black Goat and Tibetan Goat, resulting in the change of the amino acid. There were two different nucleotides between Lezhi Black Goat and Tibetan Goat for IGF-Ⅰand IGF-Ⅱgene. The different nucleotides didn't change the amino acid sequences.(3) The tissue mRNA expression levels of the GH, IGF-Ⅰand IGF-Ⅱ. The pituitary, uterus and ovary were collected from Lezhi black goat (n=6) and Tibetan goat (n=6) which were on the first day of estrus. The mRNA expression levels of the GH, IGF-Ⅰand IGF-Ⅱwere detected by Real-time PCR. GAPDH was chosen for data normalization. The result demonstrated that the mRNA expression level of GH, IGF-Ⅰand IGF-Ⅱwere different in different tissue between Lezhi black goat and Tibetan goat on the 1st day of estrus.This is, as far as we known, the first report of polymorphism of GH,IGF-Ⅰand IGF-Ⅱgenes and their relationships with prolificacy, and cloning and mRNA expression levels of GH, IGF-Ⅰand IGF-Ⅱgenes of Lezhi Black goat. This provided valuable information to understand prolific mechanism of this animal breed.