斑节对虾Sox基因HMG盒的PCR扩增及SSCP分析

PCR amplification and SSCP analysis of Sox gene HMG-box in Penaeus monodom

SRY基因是人类及哺乳动物睾丸决定因子的最佳候选基因,HMG盒是SRY基因编码蛋白质的唯一功能区,在性别决定中极其重要且高度保守,许多进化程度上明显不同的物种中都能检测出SRY基因的HMG盒,即Sox基因。斑节对虾是一种重要经济虾类,其性别决定机制研究薄弱,至今未找到性染色体。本研究根据人的SRY基因的HMG盒保守区的核苷酸序列,设计了1对兼并引物,通过PCR扩增出斑节对虾的Sox基因,并对扩增产物进行SSCP分析。结果表明,斑节对虾雌雄个体均存在Sox基因,从雌雄个体中均扩增出约350bp和220bp两条基因片段,推测其中350bp片段含内含子,SSCP结果显示斑节对虾内存在Sox基因家族的不同成员,且雌雄存在差异。最后我们讨论了对虾性别决定可能的机制。

SRY（sex-determining region of the Y chromosome） gene plays a key role in sex determination in the mammal and some evidences suggest that SRY encodes the TDF （testis determining factor） that is required for male sex determination. Sox genes are closely related to the SRY and code for proteins with a characteristic DNA-binding motif known as SRY-type HMG （high mobility group） box. A large number of Sox genes have been found in a wide variety of species throughout the animal kingdom, from human to Drosophila. Penaeths monodom is an important economical species and its heteromorphic sex chromosomes have not been found. So far, little information is known about P. monodom＇s molecular genetics of sex determination. In this paper, the technique of PCR is used to amplify the Sox genes of P. mondom with a pair of primers which specially amplify the conservation sequences of man HMG-box gene. In addition, the technique of SSCP（single strand conformation polymorphism） is used to analyze the amplification products. The results of PCR and SSCP analysis suggest： 1 ）The lengths of the fragments of PCR products are about 350 bp and 220 bp in both female and male shrimps. 2）There are Sox genes in these shrimps. 3） Introns are also found in Sox genes which is 350 bp. 4） There are different Sox genes in female and male shrimps. And the sex-determining mechanism of prawn is also discussed.