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Genomic action of steroid hormone in the silkworm brain during morphogenesis.

形态发生过程中蚕脑中类固醇激素的基因组作用。

基本信息

批准号：
15580039
负责人：
IWAMI Masafumi
金额：
$ 2.05万
依托单位：
Kanazawa University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

项目摘要

The steroid hormone, 20-hydroxyecdysone (20E), triggers the major developmental transitions of insects including molting and metamorphosis. 20E regulates target genes directly through the receptor and executes development. The dynamic morphological changes of the brain during metamorphosis such as the formation of optic lobes are also caused by 20E action. In the silkworm Bombyx mori, the 20E level is controlled by the prothoracicotropic hormone (PTTH) and PTTH is produced by the two pairs of lateral neurosecretory cells in the brain. Beside PTTH, the brain produces peptide hormones necessary for metamorphosis. The insect brain is thus the center of insect developmental control and the 20E action in the brain governs the post-embryonic development including the morphological change of the brain itself. However, the genomic response to 20E in the brain during metamorphosis has not been identified systematically.We therefore performed comprehensive expression analysis of the 20E-responsive genes of Bombyx brain with a microarray on which over 80% of total Bombyx genes are arranged and with a 20E-inducible cDNA library. We focused on the direct genomic response by 20E during metamorphosis and have identified 93 up-regulated and 97 down-regulated genes from the microarray and at least 7 genes from the cDNA library. In situ hybridization showed that major expression site of these genes characterized is at the PTTH-producing cells (PTPCs). One of the ecdysone receptor complex genes, EcR-A is also up-regulated by 20E and their mRNAs were detected exclusively in PTPCs in the larval brain. This result indicates that PTPCs are the major 20E-responsive cells in the larval brain and suggests that PTPCs are the master cells of insect metamorphosis.

类固醇激素，20-羟基蜕皮激素(20E)，触发昆虫的主要发育转变，包括蜕皮和变态。20E通过受体直接调节靶基因，并执行发育。变态过程中大脑的动态形态变化，如视叶的形成，也是由20E作用引起的。在家蚕中，20E水平由促胸腺激素(PTTH)控制，PTTH是由大脑中的两对侧向神经分泌细胞产生的。除了甲状旁腺激素外，大脑还会产生变态所必需的多肽激素。因此，昆虫的大脑是昆虫发育控制的中心，大脑中的20E活动控制着胚胎后的发育，包括大脑本身的形态变化。然而，在变态过程中，脑中对20E的反应还没有得到系统的鉴定，因此，我们利用80%以上的家蚕基因在其上排列的微阵列和20E可诱导的cDNA文库，对家蚕脑中的20E反应基因进行了全面的表达分析。我们重点研究了20E在变态过程中的直接基因组反应，从芯片中鉴定了93个上调基因和97个下调基因，从cDNA文库中至少鉴定了7个基因。原位杂交结果表明，这些基因的主要表达部位位于PTTH产生细胞(PTPC)。作为蜕皮激素受体复合体基因之一，ECR-A也被20E上调，其mRNAs仅在幼虫大脑的PTPC中检测到。这一结果表明，PTPC是幼虫脑中主要的20E反应细胞，表明PTPC是昆虫变态的主要细胞。