家蚕(Bombyx mori)光泽小眼(varnished eye,ve)突变体是家蚕突变品种中少数关于家蚕复眼形态异常的自然隐性突变品种之一,表现为成虫复眼小,表面富有光泽,有瘤状突起;小眼数量少且不规则。经典遗传学连锁图谱将ve基因定位在第6连锁群32.2座位,但到目前为止,该突变性状的形成机理仍不清楚。文章以突变品种ve和对照品种Dz为亲本,杂交产生的F1代雄个体与轮回亲本ve雌个体回交产生的BC1代为材料进行ve基因的精细定位。通过对ve低密度连锁图谱分析发现,ve基因被定位在SNP3~SNP6之间,物理图谱距离大约为1.2 Mb。利用1563个BC1代个体构建ve高密度连锁图谱,最终将ve基因定位在SNP5~SNP61之间,物理图谱距离大约为221.8 kb。通过家蚕基因数据库对ve最终定位区域内进行预测基因检索,发现有6个预测基因。对6个预测基因进行生物信息学分析和测序,这些候选基因都有可能参与家蚕复眼形成,但在编码区没有发现ve特异的突变位点;对这些候选基因进行表达分析,发现编号为BGIBMGA013642的候选基因在ve复眼形成过程中的表达量明显比正常对照Dz低,推测该基因为最佳候选基因。
The varnished eye (ve) mutant is one of the rare natural recessive mutants related to the abnormal phenotypes in the compound eye of silkworm (Bombyx mori). The compound eyes of the ve adults are smaller and glossier than those of the wild-type Dazao (Dz) and many tumor-like bumps are present on their surface; their small eyes are irregularly arranged and are smaller and fewer than those of the wild-type. The mutant gene ve has been located at the 32.2 locus of chromosome 6 in the classic genetic linkage map. However, it still remains unknown about the mechanism responsible for the mutant. In this study, we got a BC1 generation using male F1 (ve×Dz) with female ve for fine mapping of this mutant gene. The results showed that ve was located in a region between SNP3 and SNP6. The physical distance is approximately 1.2 Mb in the low density linkage map. By constructing a high-density map using 1563 BC1 individuals, the ve mutant gene was further mapped into a region between the SNP5 and SNP61. The physical region is about 221.8 kb and contains six potential genes but no specific mutations were found in the CDSs of these candidate genes. RT-PCR showed that the expression of BGIBMGA013642 was decreased obviously compared with that in wild type, suggesting it might be a key candidate gene for further studying the ve mutant.
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