The Cloning Of Horse Growth Hormone Gene And PCR-SSCP On Partial Sequence

In this thesis, full sequence of horse growth hormone gene which is 1923bp including all the exons and introns of 6 breeds was amplified by PCR. The amplification products were cloned, sequenced and submitted in GenBank (accession AY837571). The sequence structure, nucleotide composition and amino acid were analyzed and full sequences of 6 breeds of horse were analyzed by PCR-SSCP. The results showed: There were 5 exons and 4 introns in horse growth hormone gene, the size of the exons were: 10bp, 161bp, 117bp, 162bp and 201bp; the sizes of the introns were: 253bp, 213bp, 199bp and 272bp. The quantity, size and site of the exons are highly conservative compared with other mammals. The analysis of nucleotide composition showed that GC content (over 60%) is abundant in horse GH gene, and the GC content of exons (61%) was more than noncoding regions of 5′and 3′ends. In the coding regions, GC was abundant at the 1st and 3rd site, and GC of 1st (84.1%) was close to full sequence′s. AT content is abundant at 2nd site. The content of codons was different among porcine breeds. The results of PCR-SSCP analysis indicate that there is polymorphism only in 5′flanking region site among 4 sites which are 5′flanking region, intron 1, exon 2 and exon 5. As the result, there are mutations in two base sites of horse GH gene sequence: T replaced C at 1719 site, G replaced A at 1743 site. This mutation result in genotype B change into A. A is the dominant Allele gene in 6 kinds of breed except Thoroughbred horse.On this polymorphism site, Wuzhumqin horse, Wushen horse and Barag horse are in a Hardy-Weinberg balance condition and Thoroughbred horse, Sanhe horse and Xinihe horse are not. In this thesis, the sequence and polymorphism of horse growth hormone gene were researched for the first time. The result is significant for rational utilization, developing and protecting of horse genetic resources of our country.