PCR-SSCP Polymorphism Study Of The Gene CYGB Exons In Gannan Yak

At present, the domestic CYGB gene research is still in its infancy. And the research ofCYGB gene of Gannan yak at home and abroad have not been reported. In this study, the fullsequence of CYGB gene of Gannan yak was cloned and sequenced. The sequence structure,composition of nucleotide, and encoded amino acid were analyzed by bioinformatics, and themolecular evolutionary tree was established. While analysising the polymorphisms in CDSsequence of the CYGB gene in Gannan yak by PCR-SSCP. The results as follows:1. By PCR amplification, we obtained the CYGB gene sequence of Gannan yak that is8484bp. Bioinformatics analysis shows:(1) The CYGB gene of Gannan yak includes four exons and three introns, exons size of143bp,232bp,164bp and34bp, intron size were5176bp,282bp and2381bp.(2) The CYGB gene of Gannan yak has slightly high level of G+C%, but the codingregions has higher G+C%compared with introns.(3) The CYGB gene of Gannan yak could encode a190amino acid polypeptide having amolecular weight of approximately21459.6D and a isoelectric point of approximately6.62.(4) There is a strong bias for each amino acid in Gannan CYGB synonymous codon usage.(5) Phylogenetic analysis showed that the CYGB gene evolutionary tree and species treeare consistent.2. By PCR-SSCP and sequencing analysis, the polymorphisms of four exons in Gannanyaks were detected. Results are as follows:(1) No point mutation was found in the region, including the entire first exon, and part ofintron.(2) The region including the entire second exon, and part of intron, no point mutation wasfound.(3) One point mutation was found in the region, including the entire third exon, and part ofintron. There were two genotypes of AA, AB in Gannan yak, by two alleles of A and B control.The groups in the genotype frequencies were0.960and0.040, allele Aand B of the frequency of0.980and0.020. And allele B in the exon regions, that is located in the third exon of114bpoccurs at the Câ†'T mutation. The Câ†'T mutation occurred at allele B that made ACC changedinto ACT in amino acid coding sequence of163thcodon. Because of ACC and ACT encodingthreonine, so that the mutation did not cause changes in the amino acid levels.(4) Two point mutations were found in the region, including the entire forth exon, and partof intron. There were three genotypes of AA, AB and AC in Gannan yak, by three alleles of A,B and C control. The groups genotype frequencies were0.800,0.100and0.100, allele A, B andC of the frequency of0.900,0.050and0.050. The Aâ†'C mutation occurred at allele B,and allele B in the3’UTR region. The other point mutation Aâ†'G occurred at allele C，that is located inthe forth exon of25bp and made TCA changed into TCG in amino acid coding sequence of188thcodon. Because of TCA and TCG encoding serine, so that the mutation did not cause changes inthe amino acid levels.