Molecular Developmental Physiology and Signal Transduction, Department of Animal Physiology and Neurobiology, Zoological Institute, K.U. Leuven, Naamsestraat 59, B-3000 Leuven, Belgium.
J Insect Physiol. 2012 Jul;58(7):890-6. doi: 10.1016/j.jinsphys.2012.03.013. Epub 2012 Mar 29.
A major breakthrough in elucidating the ecdysteroid biosynthetic pathway in insects was realized with the molecular identification and further functional characterization of the 'Halloween' genes. These genes were found to encode cytochrome P450 enzymes catalysing the final steps of ecdysteroid biosynthesis in the dipteran, Drosophila melanogaster, and in the Lepidoptera, Manduca sexta and Bombyx mori. A recent report focused on the identification of Halloween orthologs in the desert locust, Schistocerca gregaria, a member of the hemimetabolous insect order of the Orthoptera. In the present study, an additional Halloween gene Shade, is identified in the desert locust. In Diptera and Lepidoptera, this gene encodes a 20-hydroxylase, catalysing the conversion of ecdysone (E) to 20-hydroxyecdysone (20E). However, this enzymatic function has previously been suggested for CYP6H1 in another locust species, the migratory locust, Locusta migratoria. Using q-RT-PCR, the spatial and temporal transcript profiles of S. gregaria orthologs for Shade as well as CYP6H1 were analysed in last larval stage desert locusts. An RNA interference (RNAi)-based approach was employed to study whether these genes could possibly encode a functional 20-hydroxylase in the desert locust.
阐明昆虫蜕皮激素生物合成途径的一个主要突破是通过“万圣节”基因的分子鉴定和进一步的功能特征来实现的。这些基因被发现编码细胞色素 P450 酶，催化双翅目果蝇和鳞翅目昆虫曼陀罗和家蚕中蜕皮激素生物合成的最后步骤。最近的一份报告集中在沙漠蝗 Schistocerca gregaria 中 Halloween 同源基因的鉴定上，沙漠蝗是半变态昆虫直翅目昆虫的一员。在本研究中，在沙漠蝗中鉴定出了另一个 Halloween 基因 Shade。在双翅目和鳞翅目昆虫中，该基因编码一种 20-羟化酶，催化蜕皮甾酮（E）转化为 20-羟基蜕皮甾酮（20E）。然而，这种酶促功能以前被认为是另一种蝗虫物种，即飞蝗，Locusta migratoria 中的 CYP6H1 所具有的。使用 q-RT-PCR 分析了沙漠蝗 last 幼虫期 Shade 和 CYP6H1 的时空转录谱。采用 RNA 干扰（RNAi）方法研究这些基因是否可能在沙漠蝗中编码具有功能的 20-羟化酶。
