Zhuo Weiwei, Fang Yan, Kong Lingfei, Li Xi, Sima Yanghu, Xu Shiqing
Department of Applied Biology, School of Biology and Basic Medical Sciences, Medical College, Soochow University, Suzhou, 215123, China.
Mol Biol Rep. 2014 Jul;41(7):4177-86. doi: 10.1007/s11033-014-3288-1. Epub 2014 Feb 28.
Chitin synthase is the key regulatory enzyme for chitin synthesis and excretion in insects, as well as a specific target of insecticides. The chitin synthase A gene (BmChsA) cloned from Bombyx mori, the model species of lepidopteran, is an epidermis-specific expressed gene during the molting stage. Knockdown BmChsA gene in 3rd instar larvae increased the number of non-molting and abnormal molting larvae. Exposure to nikkomycin Z, a chitin synthase inhibitor downregulated the expression of BmChsA and decreased the amount of epidermis chitin during the molting process. The thickness of the new epidermis and its dense structure varied greatly. The exogenous hormones significantly upregulated the expression of BmChsA with low levels of endogenous MH and high levels of endogenous JH immediately after molting. With low levels of endogenous hormones during the mulberry intake process, BmChsA was rarely upregulated by exogenous hormones. With high levels of endogenous MH and low levels of endogenous JH during the molting stage, we did not detect the upregulation of BmChsA by exogenous hormones. The expression of BmChsA was regulated by endocrine hormones, which directly affected the chitin synthesis-dependent epidermal regeneration and molting process.
几丁质合成酶是昆虫几丁质合成与排泄的关键调节酶，也是杀虫剂的特定作用靶点。从鳞翅目模式物种家蚕中克隆的几丁质合成酶A基因（BmChsA）是蜕皮期表皮特异性表达基因。敲低三龄幼虫的BmChsA基因会增加不蜕皮和异常蜕皮幼虫的数量。暴露于几丁质合成酶抑制剂多氧霉素Z会下调BmChsA的表达，并在蜕皮过程中减少表皮几丁质的含量。新表皮的厚度及其致密结构差异很大。蜕皮后，外源性激素在低水平内源性蜕皮激素（MH）和高水平内源性保幼激素（JH）时显著上调BmChsA的表达。在摄食桑叶过程中，内源性激素水平较低时，外源性激素很少上调BmChsA的表达。在蜕皮期，内源性MH水平高而内源性JH水平低时，我们未检测到外源性激素对BmChsA的上调作用。BmChsA的表达受内分泌激素调节，这直接影响了依赖几丁质合成的表皮再生和蜕皮过程。
