家蚕淡红卵突变体(rep-1)的发现及卵色相关基因MFS的结构分析

Discovery of the Pale Red Egg(re^p-1) Mutant in Bombyx mori and Structure Analysis of MFS Gene Related to Egg Color

在家蚕品种C1(H)中发现了一种新的卵色突变体。该突变体卵色为淡红色,成虫复眼为红色,遗传分析表明该突变性状由1个隐性基因控制,可能与红卵突变基因re互为等位基因,命名为淡红卵突变体(pale red egg,re^p-1)。红卵突变体(re)被认为是MFS(major facilitator superfamily)基因的序列发生了改变,故对re^p-1突变体MFS基因的结构及表达进行分析。与C1(H)卵色正常型品系的MFS基因比较,re^p-1突变体的MFS基因在第6外显子中的一段长59 bp片段被长14 bp的片段所替换,但编码蛋白质的跨膜结构未发生根本改变,而re突变体中MFS基因的结构变化对表达产物的功能有显著影响。此外,利用qRT-PCR检测MFS基因在C1(H)的卵色正常型品系、re^p-1突变体和re突变体3个家蚕品系5龄幼虫各个组织中均有表达,但表达水平存在差异:相较于C1(H)卵色正常型品系和re^p-1突变体,re突变体所有组织中MFS基因的表达量普遍偏低;相较于C1(H)卵色正常型品系,re^p-1突变体的后部丝腺和精巢中MFS基因具有较高的表达量,在其他组织中的表达量无明显差异。上述结果将有助于对re^p-1突变基因定位分析和卵色突变形成机制的研究。

A novel silkworm（ Bombyx mori） egg color mutant was found in silkworm variety C1（ H）. The mutant egg color exhibits light red,and the mutant eye color is red. Genetic analysis revealed that the mutant trait is controlled by a recessive gene,which might be the allelic gene of red egg mutant gene re. Thus,the mutant is named as pale red egg 1（ rep-1）. Previous research revealed that the red egg mutant（ re） is resulted from the change of MFS（ major facilitator superfamily） gene. Therefore,in this study,we analyzed the structure and expressed of MFS gene in rep-1 mutant.The results showed that a 59 bp fragment was replaced by a 14 bp fragment in the 6 th exon of MFS gene in rep-1 mutant when compared with that of normal type C1（ H）.Yet,there was no critical change in transmembrane structure of the encoded protein. Compared with the normal type,the structural variation of MFS gene in re mutant had significant influence on the function of expressed product. In addition,qRT-PCR was applied to test the expression of MFS gene in different tissues from normal type C1（ H）,rep-1 mutant and re mutant respectively. It was found that MFS gene was expressed in all tissues of the 5 th instar larvae of three silkworm varieties but with various expression levels. Compared with C1（ H） and rep-1 mutant,the expression level of MFS gene in all tissues of re mutant was generally lower. Compared with normal type C1（ H）,the expression levels of MFS gene in posterior silk gland and testis of rep-1 mutant were relatively higher,and there was no obvious difference in other tissues.The above results will help to locate the rep-1 mutant gene and explore the mutation mechanism of egg color in silkworm.