尖唇散白蚁工蚁向补充生殖蚁和兵蚁转化过程中生殖力分化及调控机理研究

Termites present the most complex and conspicuous caste systems. There are three castes in a colony of termite, including reproductives,workers and soldiers. The differential reproduction phenotypes can be driven to an extreme, turning the reproductives into an egg-laying machine, whereas the workers and soldiers are curtailed in fertility to functional or complete sterility. Especially,workers in termite colony are characterized by great flexibility that a worker can develop in three ways: stay as workers, become soldiers through two successive moults,or evolve into neotenic reproductives that develop in the absence of or at a great distance from the primary reproductive provide for continued or additional growth of the colony.It is very important for a colony survival and expansion that workers are characterized by great flexibility in development.Reproductive division is the key feature during workers developing into neotenic reproductives or into soldiers. Dynamic changes of gonad in termite have not been definitively determined,and remarkably it is in Reticulitermes that evidence for a genetic control or environment control of caste determination was disputed.In the present study we will investigate changes of gonad development in the termite Reticulitermes aculabialis during isolated workers developing into neotenic reproductives and soldiers by histological analysis,BrdU and TUNEL labeling experiments in order to expound dynamic changes and proliferation and apoptosis of germ cells at various stage,and the germ cells of workers which is induced by juvenile hormone treatment are studied.The pheromones which induce workers turning into neotenic reproductions and soldiers will be investigated. Microsatellite DNA is used for understand whether have genetic influence on which individual in worker colony can succceed in evolving into neotenic reproductive or soldier. Further,morphologically and behaviorally distinct are compared between the workers which will development into neotenic reproductives and the workers which stay as workers.On the basis of these results,we will reveal the reproductive division and regulation mechanism in termite during workers developing into reproductive and sterile soldiers,and in a worker group,which one will development into neotenic reproductives is controlled both by environment and a complex genetic inheritance pattern，and whill provide a new way for termite control and resource utillzation．

工蚁是白蚁巢中最具活力的品级，其分化的可塑性对巢群的生存和发展具有极其重要的作用。生殖能力的分化是工蚁向补充生殖蚁或兵蚁转化过程中最主要的特征，目前其转化机理尚不清楚，尤其由"哪类工蚁会转化"疑问引起的工蚁个体选择性转化的决定机制问题国内外还未涉及。本项目以我国广泛分布的危害蚁种尖唇散白蚁为对象，在项目组十几年研究的基础上，于实验室隔离培养，通过对工蚁转化过程中的性腺动态发育、基于DNA合成和降解的生殖细胞增殖和凋亡规律，以及在保幼激素诱导下的生殖细胞发育行为研究，确定生殖力开始出现分化的时间、动态变化规律和细胞学基础；检测确定诱导和抑制工蚁转化的信息素有效成分，阐明转化的诱导启动机制；并应用微卫星DNA标记进行多态性分析，探讨转化个体和不转化个体是否具有遗传选择机制。藉此揭示工蚁向两个极端品级转化的调控机理和白蚁巢群内品级结构发展规律，并为白蚁防治和白蚁资源利用新技术的开发提供新的依据。

品级分化是白蚁群体维持生存和扩张的方式，工蚁发育可塑性一直是白蚁研究的关键问题。我们揭示了工蚁向两个极端品级转化的机理和巢群内繁殖体系，为白蚁防治和白蚁资源利用新技术开发提供依据。 .1. 研究工蚁、生殖蚁和兵蚁性腺发育形态学特征，以及基于DNA合成和降解的生殖细胞增殖和凋亡动态变化。阐明滤泡细胞退化引起卵母细胞停止发育是导致工蚁具有发育可塑性的原因，各品级生殖能力差异由卵原细胞凋亡调控。 .2. 首次发现雄性工蚁发育的可生殖途径和非生殖途径，阐明雄性工蚁可以直接参与生殖。根据各龄期雄性工蚁生殖细胞发育和微卫星DNA标记，揭示雄性工蚁向补充生殖蚁和兵蚁转化具有个体发育选择性，即老龄有精子工蚁可以直接交配，兵蚁由无精子工蚁优先分化而来。.3.研究雌性工蚁向补充生殖蚁转变的机理。首次发现雌性工蚁向生殖蚁转变需经历2次蜕皮，即先经过一个拟生殖蚁阶段；雌性老龄工蚁个体都具有向生殖蚁转化的潜能。揭示卵母细胞激活是工蚁向生殖蚁转化经历2次蜕皮的主要原因。.4.在圆唇散白蚁中发现新型补充生殖蚁即拟成虫型补充生殖蚁，并探讨补充生殖蚁对巢群稳定和发展的作用。研究拟成虫型和翅芽型生殖蚁分化过程中保幼激素水平和卵黄原蛋白基因表达，阐明保幼激素调控不同类型生殖蚁分化。.5.完成原始生殖蚁和补充生殖蚁转录组测序，获得61,953个unigenes。对64个表皮蛋白基因分析和qRT-PCR测定发现与外表皮和翅硬化相关基因RR-2和CPG、以及内表皮相关基因RR-1在原始生殖蚁中高表达。阐明个体成为原始生殖蚁还是补充生殖蚁与体壁有关；拟成虫是原始生殖蚁和翅芽型补充生殖蚁之间进化过程中的过渡类型。.6.发现尖唇散白蚁的孤雌生殖行为，探究散白蚁两性生殖和孤雌生殖胚胎的发育特征。确定黑胸散白蚁未受精卵死亡点在卵裂15-20d；阐明雌雌配对和雌雄配对初建群体在发育模式上有显著差异；仅少数白蚁种类能孤雌生殖可能与其群体内的雄性生殖力有关。