色素代谢相关基因在家蚕褐色类鹑斑突变品系q-l^b 4龄眠蚕表皮中的表达分析

Expression Analysis of Pigment Metabolism-related Genes in the Epidermis of the 4th Instar Molting Larvae of q-l^b Mutant of Silkworm,Bombyx mori

家蚕体表色素主要有黑色素、蝶啶类色素和眼色素,不同家蚕品种的体色和斑纹都是表皮中黑色素、眼色素和蝶啶类色素等相互作用的结果。为了解家蚕褐色类鹑斑突变体(brown quail-like,q-l^b)幼虫表皮色素的代谢情况,利用qRT-PCR 技术分别检测q-l^b突变体和其对应的野生型品种0223金黄(0223JH)在4龄入眠后18 h新生表皮中37个色素代谢相关的基因的表达水平。结果表明,相对于野生型品种,大多数与黑色素、蝶啶类色素合成相关的关键基因在q-l^b突变体中表达上调,而与眼色素合成相关的关键基因表达下调,表明黑色素、蝶啶类色素在q-l^b突变体表皮中的含量都增加,而眼色素在q-l^b突变体表皮中的含量相对减少;与几丁质合成及尿酸转运相关的基因在q-l^b突变体表皮中也存在表达差异,其中大部分关键基因表达上调,表明更多的几丁质在q-l^b突变体新生表皮中合成,并伴随更多的尿酸被转运到表皮,与其他色素一起参与表皮构建,形成q-l^b突变体特殊的体色斑纹。此外,部分保幼激素代谢和核受体基因差异表达也可能影响了相关色素的合成及代谢。q-l^b突变体相对于野生型具有更复杂的体色和斑纹,这些基因的差异表达可能与此有关。研究结果为进一步阐述家蚕褐色类鹑斑产生的分子机制打下了基础。

Epidermis pigment of silkworm (Bombyx mori) is mainly composed of melanin,ommochrome and pteridine.All skin color of silkworm larvae is based on the interaction of melanin,ommochromes and pteridines etc. In this study,37 genes in the epidermis of q-l^b mutant 18 hours after 4th instar molting related to pigmentation were analyzed by quantitative reverse transcription PCR (qRT- PCR)with its wild-type strain 0223JH as the control.Results showed that many key genes involved in biosynthesis of melanin and pteridine were up-regulated in q-l^b,while key genes related to ommochrome biosynthesis were down-regulated,which indicated that the contents of melanin and pteridine increased but ommochrome content decreased in q-l^b mutant.Key genes in chitin synthesis and genes related to uric acid transportation were differentially expressed in q-l^b mutant as compared with wild-type 0223JH.Most of the key genes were up-regulated,which implicated that there were more chitin produced in newly grown epidermis of q-l^b mutant,and more uric acids were transported to cuticula,participating epidermis construction with other pigments and forming special body marks in q-l^b mutant.In addition,certain genes related to juvenile hormone metabolism and several nuclear receptor genes were differentially expressed between ql^b and 0223JH.These genes might also contribute to the pigmentation in q-l^b mutant.These differentially expressed genes might be responsible for the phenotype of q-l^b. Our research establishes a good foundation for further elucidation on molecular mechanism of pigmentation in the q-l^b mutant.