鳙Sox基因克隆及序列进化分析

利用简并引物SoxN和Sox9在鳙基因组DNA中进行PCR扩增和产物克隆测序，并对序列进行同源性比较和系统进化分析。结果表明本文鉴定出鳙15个Sox基因HMG盒序列，分别属于SoxB、SoxC和SoxE组，依据斑马鱼同源基因将其分别命名为Sox1a、Sox1b、Sox2、Sox3、Sox4a、Sox4b、Sox9a、Sox9b、Sox10、Sox11b、Sox12、Sox14a、Sox14b、Sox19和Sox21a。基于鳙和斑马鱼 Sox1、Sox4和Sox9 基因核苷酸序列构建的系统进化树显示这3个Sox基因的复制时间发生在鳙和斑马鱼的分化之前，结果支持了鱼类特异的基因组复制假说。以Sox1a、Sox1b和Sox4基因为分子钟标记构建系统进化树探讨鳙和斑马鱼的分化时间，结果显示，同属于鲤科鱼类的鳙（鲤亚科）和斑马鱼（鱼丹亚科）在原始的鱼丹亚科鱼类中存在一个共同祖先，大约出现在63.7百万年前。研究结果为进一步研究鱼类Sox基因复制和基因组进化等问题提供了重要参考资料。  

CLONING AND SEQUENCE EVOLUTION ANALYSIS OF SOX GENESIN BIGHEAD CARP (ARISTICHTHYS NOBILIS)

To amplify Sox genes from bighead carp genome, two pairs of degenerate primers (SoxN and Sox9) were designed for PCR amplification that were utilized for sequencing and analysis of sequence homology and phylogenetic relationships. The results showed that 15 distinct Sox genes encoding the HMG domains were identified in bighead carp, which were assigned to group B, C and E. According to their homology to orthologs of zebrafish, 15 Sox genes were designated as Sox1a, Sox1b, Sox2, Sox3, Sox4a, Sox4b, Sox9a, Sox9b, Sox10, Sox11b, Sox12, Sox14a, Sox14b, Sox19 and Sox21a, respectively. Phylogenetic tree of Sox1, Sox4 and Sox9 nucleotide sequences indicated that the duplication of these three Sox genes occurred before the divergence of bighead carp and zebrafish, and this observation supported the fish-specific whole-genome duplication theory. Using Sox1a, Sox1b and Sox4 as molecular clock markers in phylogenetic analysis, the estimation of the divergence time between bighead carp and zebrafish demonstrated that in original Danioninae, a common ancestor appeared approximately 63.7 million years ago for bighead carp and zebrafish, both of which belong to Cyprinidae. This study would provide important information for further studies of Sox gene replication and genome evolution in fish.