Molecular mechanisms controlling circadian rhythms and photoperiodism in insects

光周期是一种重要的生物学机制，与农业生产密切相关，但其分子机制尚不清楚，本研究从光感受、昼夜节律振荡和内分泌开关等方面分析了光周期系统的结构、定位和动力学，以期重建光周期系统。使用不同的昆虫的比较研究发现，在昼夜节律起搏器的结构和感光器方面的个体发育阶段和系统发育线相当大的灵活性。吲哚胺能途径是光周期系统的重要调节因子，因为催化褪黑素产生的N-乙酰转移酶（NAT）上游调控区有多个与转录因子CLK/CYK结合的E-box，分泌促前胸激素激素（PTTH）的细胞表达褪黑素受体，所有含PER的细胞都有NAT，褪黑素含量和NAT转录水平呈现昼夜振荡。这些细胞具有视网膜外光感受性。

Photoperiodism is an important biological mechanism and involved in agriculture production but its molecular mechanism remains obscure.This study analyzed the structures, localization and dynamics of the elements involved in photoreception, circadian oscillation and endocrine switch to reconstruct the photoperiodic system. Comparative studies using different insects revealed a considerable flexibility in the circadian pacemaker structure and photoreceptor regarding to ontogenetic stages and phylogenetic lines. The important factor mediating photpoperiodic system seems to be the indolaminergic pathway, since the upstream regulatory region of N-acetyltransferase(NAT) that catalyze the production of melatonin has several E-boxes where transcription factors CLK/CYK binds, the cells secreting prothoracicotropic horone (PTTH) express melatonin receptor and all PER containing cells have NAT, and melatonin content and NAT transcript level show a circadian oscillation. These cells have the extraretinal photoreception.