Neuropeptide hormone of insect : molecular mechanisms and tissue responses

目前的科研项目从1996年至1998年财政年度进行了三年。最初的目标是阐明昆虫变态和胚胎滞育的神经肽激素表达及其生理效应的分子机制，我们认为已经达到了可观的水平。由30个基因拷贝组成，并已完成了它们在拟南芥基因组中的表达模式和所有30个基因上游区的核苷酸序列。通过cDNA克隆也证实了胰岛素受体具有类似于胰岛素受体的酪氨酸激酶domein。建立了时间分辨荧光免疫分析（TR-FIA）测定家蚕毒素的超微量分析方法，该方法能定量测定低至几阿摩尔的极微量激素，并能详细测定幼虫-蛹-体血淋巴中家蚕毒素浓度的变化。 ...更多信息 成年期相同的方法变得适用于测量血淋巴PTTH滴度，其显示甚至在头临界期（HCP）之前PTTH的每日分泌。PTTH分泌受神经递质乙酰胆碱刺激，表明乙酰胆碱神经元可能参与PTTH细胞的调节。作为PTTH刺激前胸腺分子机制的一部分，PTTH受体的纯化及其物理性质的阐明正在进行中。滞育激素（DH）mRNA的表达动态表现出不同的胚胎和幼虫阶段的动物，注定要生产滞育卵从那些生产非滞育卵。其中一个主要的DH效应与海藻糖酶基因在卵巢中的表达有关。DH基因在食管下神经节的3个神经分泌细胞簇中均有表达。DH从后簇加工和分泌，而信息素生物合成激活神经激素从前簇和中簇分泌，所述信息素生物合成激活神经激素从与DH相同的前体分子加工。如上所述，本研究项目成功地为理解昆虫变态中神经肽激素的分子机制提供了基础知识。少

The present scientific research project has been carried out over 3 years from the 1996 to 1998 fiscal year. The initial objective was elucidation of the molecular mechanisms underlying insect metamorphosis and embryonic diapause in respect to the expression of neuropeptide hormones and their physiological effects and we consider to have reached the goal at an appreciable level.Bombyxin, an insulin-related neuropeptide, consists of 30 gene copies and their expression pattern in Bombyx genome and the nucleotide sequences of upstream region of all the 30 genes have been accomplished. Bombyxin receptor has also been elucidated by cDNA cloning to possess the tyrosine kinase domein similar to insulin receptor. Ultra-micro assay method of bombyxin was developed using time-resolved fluoroimmunoassay (TR-FIA) which enabled to quantify a very small amount of the hormone as low as few atto-moles and to determine the detailed changes in hemolymph bombyxin concentrations through the larval-pupal-a … More dult period. The same method became applicable to measurement of hemolymph PTTH titer, which showed a daily secretion of PTTH even before head critical period (HCP). PTTH secretion is stimulated by a neurotransmitter, acetylcholine, indicating that acetylcholine neuron may be involved in the regulation of PTTH cells. As a part of elucidation of molecular mechanisms of PTTH stimulation of prothoracic glands, purification of PTTH receptor and elucidation of its physical properties are in progress. Expression dynamics of diapause hormone (DH) mRNA showed to be different in embryonic and larval stages of animals that are destined to produce diapausing eggs from those to produce non-diapausing eggs. One of the major DH effects was involved in the expression of trehalase gene in ovary. DH gene was expressed in 3 clusters of neurosecretory cells in suboesophageal ganglion. DH is processed and secreted from the posterior cluster while pheromone biosynthesis activating neurohormone which is processed from the same precursor molecule as DH is secreted from the anterior and middle clusters. As described above, the present research project succeeded to give fundamental knowledge on understanding the molecular mechanisms of neuropeptide hormones involved in insect metamorphosis. Less