Caste Determination in the Polyembryonic Wasp Copidosoma Floridanum

***多表型是指一个物种在响应其内部或外部环境的提示时出现不同的表型。大多数关于昆虫多表型的研究都集中在环境和内分泌因素对表型可塑性的影响上。这种观点暗示，个体最初是双潜能的，但在关键时期，特定的刺激不可逆转地使他们成为特定的种姓。影响昆虫多表型的环境因素已经被研究了很多次，但是这些因素如何影响细胞或分子水平上的形态发生事件在很大程度上是未知的。研究这些问题的一个有用的系统是一组独特的多胚胎寄生蜂（拟寄生蜂）。拟寄生物将卵产在其他昆虫身上或体内，这些昆虫是其幼虫发育的食物。多胚黄蜂产下的每一枚卵都会克隆分裂，产生一窝基因相同的兄弟姐妹，它们在宿主体内一起觅食。一些种类的卵形成1000多个胚胎和两种形态不同的幼虫：发育成成年黄蜂的生殖幼虫和具有工蜂功能的早熟幼虫。在本提案中，我们寻求资金来研究多胚黄蜂（Copidosoma floridanum）的种姓形成，这是一种攻击Trichopulsiani蛾的多胚黄蜂。我们的背景数据将使我们能够描述细胞谱系和内分泌因素如何与调节模式形成的基因相互作用。该提案的目的是：1)评估细胞谱系在种姓决定中的作用，2)检查宿主内分泌因素对种姓的影响，以及3)表征模式形成基因在早熟和生殖形态中的时空表达。对于谱系研究，命运图将通过使用荧光标记的葡聚糖示踪剂和/或辣根过氧化物酶注射选定的卵裂球来生成。内分泌研究将采用一系列移植、消融和抢救策略，而模式形成将通过监测模式基因同源物的表达来检查。我们的研究将为我们理解多胚胎、调节可选多表型的细胞/分子机制以及影响发育进化的过程提供基础信息。* * *

*** Polyphenism refers to the occurrence of alternative phenotypes in a species in response to cues from its internal or external environment. Most studies on insect polyphenisms have focused on how environmental and endocrine factors affect phenotypic plasticity. Implicit in this view is that individuals are initially bipotential but at a critical period, specific stimuli irreversibly commit them to a particular caste. Environment factors that influence insect polyphenisms have been examined many times previously, but how these factors impact morphogenetic events at the cell or molecular level is largely unknown. A useful system for studying these questions is a unique group of parasitic wasps (parasitoids) that are polyembryonic. Parasitoids lay their eggs on or in the bodies of other insects, which act as food for the develop larvae. Each egg laid by a polyembryonic wasp divides clonally to produce a brood of genetically identical siblings that feed together inside the host. The eggs of some species form more than 1,000 embryos and two morphologically distinct laral castes: reproductive larvae that develop into adult wasps and precocious larvae that have worker functions. In this proposal, we seek funds to study caste formation in Copidosoma floridanum, a polyembryonic wasp that attacks the moth Trichopulsiani. Our background data will allow us to characterize how cell lineage and endocrine factors interact with genes regulating pattern formation. Objectives of the proposal are to: 1) assess the role of cell lineage in caste determination, 2) examine the influence of host endocrine factors on caste, and 3) characterize spatial/temporal expression of pattern-forming genes in the precocious and reproductive morphs. For lineage studies, fate maps will be generated by injecting selected blastomeres using fluorescently conjugated dextran tracers and/or horseradish peroxidase. Endocrine studies will employ a series of transplantation, ablation and rescue strategies, while pattern formation will be examined by monitoring expression of pattern gene homologs. Our study will contribute fundamental information to our understanding of polyembyrony, the cellular/molecular mechanisms regulating alternative polyphenisms, and the processes influencing developmental evolution. ***