家蚕不同茧色品种中cbp基因的结构和表达分析

Structure and expression analysis of cbp gene in different natural colored-cocoon strains of Bombyx mori

类胡萝卜素结合蛋白(CBP)是唯一已被确认与家蚕黄色茧形成密切相关的主要蛋白质。文章选择12个有色茧和白茧蚕品种,调查了cbp基因结构、转录产物mRNA类型和丝腺类胡萝卜素紫外可见光吸收特征与其茧色的关系。结果表明:黄色茧蚕品种含有2种或3种cbp基因结构,同时转录具有CBP功能性的完整mRNA和缺少第2外显子的mRNA;绿茧品种间cbp基因结构存在差异,转录缺少第2外显子的mRNA;白茧蚕品种cbp基因只有1种结构,转录缺少第2外显子的mRNA。文章在黄茧品种中新发现的cbp基因第1内含子序列可能具有茧色品种特异性,家蚕黄茧品种丝腺的紫外可见吸收光谱特征显著区别于绿茧和白茧品种,cbp基因的结构和表达特征与家蚕茧色密切相关。

Carotenoid-binding protein （CBP） is the only key protein that has been characterized to be involved in yellow cocoon coloration of the domesticated silkworm （Bombyx mori）. Gene structure and mRNA expression profiles of cbp along with UV-Vis spectrum profiles of carotenoids in silk glands were investigated among twelve strains to disclose their relationship with cocoon color. Yellow cocoon strains of B. mori contained two or three cbp gene types, which had different mRNA products with a longer form acting functionally to code CBP protein and the smaller one without exon 2. The structures of cbp were different among the green cocoon strains with the mRNA product lacking exon 2. Only one cbp gene structure existed in white cocoon strains of B. mori, which produced the mRNA product free of exon 2. A newly identified intron 1 sequence of cbp gene in this study may have cocoon color-specificity among strains. The UV-Vis spectrum profiles of carotenoids in the yellow cocoon strains’ silk glands were significantly different from those in the green cocoon strains and white cocoon strains.Together, it can be concluded that the gene structure and expression profile of cbp was closely linked to cocoon colors of B. mori.