水牛-β-LG基因3，4外显子遗传特征分析

 本文通过PCR产物直接测序法得到水牛β-LG基因第3，4外显子及其旁侧序列后，采用PCR-RFLP和PCR-SSCP方法对属于10个群体的224头水牛该基因第4外显子进行了多态性检测，又从中随机抽取属于9个群体的69头水牛采用PCR-SSCP结合测序的方法检测了其第3外显子的遗传多态性。结果显示：河流型水牛和沼泽型水牛β-LG基因的第3外显子均为74 bp；它们的第4外显子均为111 bp；在所研究群体中，两类水牛第3，4外显子序列完全相同，并未发现具有多态现象。与牛科物种同源序列比较显示：水牛β-LG基因3，4外显子在进化上比较保守，相应于普通牛的B等位基因。由于产奶量有明显差异的河流型水牛与沼泽型水牛的β-LG基因第3，4外显子序列间无差异，提示它们对水牛产奶量无直接影响。

Genetic Characteristics of the Exon 3 and 4 of β-LG in Buffalo

In this study,exon 3 and exon 4 plus their flanking segments of β-LG were amplified and sequenced in buffalo firstly. The polymorphisms of exon 4 of β-LG in 224 buffaloes belonging to 10 populations were investigated by means of PCR-RFLP and PCR-SSCP. Then we selected randomly 69 individuals from the 224 buffaloes to detect their polymorphisms of exon 3 of β-LG by PCR-SSCP and sequencing. The results showed that exon 3 and exon 4 of  β-LG in both river and swamp buffalo were 74 bp and 111 bp long, respectively. The sequences of exon 3 and exon 4 of β-LG had 100% identity and monomorphism were observed for the buffalo populations studied. Compared with homologous sequence of bovine species, the sequences of exon 3 and exon 4 of β-LG are conservative, and the protein sequences in buffalo is the same with those coding by B allele in Bos taurus. There was no difference in the sequences of exon 3 and exon 4 of β-LG between both kind of buffalo, but they have significant difference in milking performance, this indicates that the exon 3 and exon 4 of β-LG have no direct effect on milk yield in buffalo.