温度变化诱导海蜇横裂生殖的调控机制

Rhopilema esculentum, an edible jellyfish with high economic value, is an important aquaculture and enhancement species in coastal areas of China. Strobilation is the only way for R. esculentum to transform from polyps to edible medusa, and therefore becomes a key stage during jellyfish artifical breeding. Early studies have shown that temperature change could induce strobilation initiation. However, how temperature change induces strobilation, or in another word, what is the mechanism of polyp responsing to temperature change? So far little is known about those issues, which constraints the development of jellyfish breeding technology. The present program is intended to investigate the influence of different temperature variation pattern on jellyfish strobilation process. High throughout transcriptome sequencing will be conducted to characterize the gene expression profile during the process that temperature change induced strobilation. Major signal transduction pathway and key genes related to strobilation induction will be identified by bioinformatics analysis. Techniques including in situ hybridization, RNA interference and real-time PCR will be used to verify the function of candidate genes in strobilation induction. The implementation of this program will elucidate the inner function way and regulatory mechanisms of strobilation induction by temperature change, which will not only provide theoretical support for the foundation of efficient breeding technology of R. esculentum, but also provide a reference for understanding the mechanism of large jellfish outbreak.

海蜇是经济价值最高的一种食用水母，也是我国沿海重要的增养殖对象。横裂生殖是海蜇水螅体向水母体转变的唯一途径，是海蜇苗种繁育的关键环节。研究表明温度变化是海蜇横裂生殖启动的重要开关，然而温度变化通过什么途径启动横裂生殖？水螅体有着怎样的横裂生殖启动机制？迄今知之甚少，因而制约了海蜇苗种繁育技术的发展。因此，本项申请拟深入考察不同温度变化模式对海蜇横裂生殖进程的影响；利用转录组测序技术构建温度变化诱导海蜇横裂生殖过程的基因表达谱；通过生物信息学分析，筛选温度变化诱导横裂生殖的主要信号通路和关键节点基因；结合实时定量PCR、原位杂交、RNA干扰（RNAi）等技术确定主要候选基因在横裂生殖中的功能，以揭示温度变化诱导海蜇横裂生殖的内在效应途径和调控机制，为建立海蜇高效苗种繁育技术提供理论支持，也为认识大型水母暴发机制提供参考。

海蜇是我国重要的特色海水养殖品种，横裂生殖是海蜇水螅体向水母体转变的唯一途径，是海蜇苗种繁育的关键环节。已知经历低温生活的螅状体通过升温能够诱导其发生横裂生殖，本项目针对这一现象内在的调控机制开展了深入研究。首先我们对海蜇横裂生殖各时期进行了转录组测序分析，通过差异基因的共表达分析获得了一个与横裂生殖相关的基因簇，该基因簇显著富集于氧化磷酸化通路以及序列特异性DNA结合转录因子结合活性、序列特异性DNA结合等GO条目，暗示了一些转录调控因子在横裂生殖中发挥着重要作用；其次，通过对螅状体与横裂生殖初期的代谢组与蛋白组分析，分别鉴定了167个差异代谢物和306个差异表达蛋白，差异代谢物中与氧化应激和炎症反应相关的类二十烷酸类有显著变化，暗示了氧化应激与免疫反应在横裂生殖启动中可能的作用。差异表达蛋白显著富集于氧化磷酸化通路、核糖体及牛磺酸合成通路，联合分析显示差异表达蛋白和代谢物在白三烯合成通路上显示了密切相关性；最后，利用RACE技术克隆了5个候选基因的cDNA全长，分析了它们横裂生殖过程的表达模式，qPCR显示它们均在横裂生殖初期和后期显著上调表达，原位杂交显示even-skipped、dmrta2和engrailed主要表达于感觉缘叶原基、感觉棍和神经束位置，说明它们主要与横裂生殖过程中神经系统的分化发育相关。总之，研究结果从组学层面初步解析了升温诱导的横裂生殖启动及发育过程的调控机制，为海蜇及其它钵水母横裂生殖分子调控机制的深入解析提供了重要参考。