RUI Collaborative Research: Genetic and Developmental Analysis of Hybrid Sterility Rescue between Drosophila Melanogaster and Drosophila Simulans

霍洛彻/戴维斯9728890当不同物种杂交时，一个引人注目且非常常见的模式是产生无法繁殖的杂交后代(即后代完全不育)。本研究旨在了解黑腹果蝇与拟果蝇杂交后代杂交不育的遗传和发育基础。早期对杂交不育的分析一直受到这样一个事实的阻碍，即所有使用这两个物种的杂交产生的后代都是完全不育的，这使得除了最初的F1杂交之外，不可能进行简单的遗传分析。最近，一种自然产生的拟态石斑菌被发现，它可以挽救与黑腹石斑菌杂交的杂交雌性的不育缺陷。由于有能力产生可生育和不育的杂交雌性，我们现在能够利用这些果蝇物种中可用的大量分子和遗传工具，在理解杂交不育的潜在遗传和发育原因方面取得进展。这项研究的第一个目的是用一种比较发育的方法来描述与杂交不育有关的配子发生中的特定缺陷。利用这种比较的方法，我们可以回答以下问题：雌性杂交不育的发展基础是什么及其拯救？不育的、未获救的杂交雌性有没有任何有功能的生殖系组织？如果是这样的话，生殖系发育的主要缺陷是什么？杂交女性不孕症抢救完成了吗？杂交不育症的挽救是否具有性别特异性？我们的第二个目标是定位导致杂交雌性不孕的遗传因素及其拯救。当与黑腹盘藻杂交时，产生不育或可育杂交雌株的拟南针菌系之间的重组体的产生将被用来确定哪些基因区域与本提案的第一个目标中描述的特定杂交不育缺陷有关。在进行作图研究的同时，还将对更多的果蝇品系进行调查，以分离新的不育拯救因素，特别关注显示杂交不育拯救的互补黑腹果蝇品系。然后，我们的最终目标是利用杂交不育挽救的优势，将一个物种的遗传物质引入另一个物种，以测试关于影响配子发生的基因在这两个物种之间如何分化的具体假设。

Hollocher/Davis 9728890 One striking and very common pattern that results when different species are crossed together is the production of hybrid offspring that are unable to reproduce (i.e. the offspring are completely sterile). This research focuses on understanding the genetic and developmental basis of hybrid sterility in offspring that result from crosses between Drosophila melanogaster and Drosophila simulans. Earlier analyses of hybrid sterility had been hampered by the fact that all crosses using these two species yielded offspring that were completely sterile, making simple genetic analyses beyond the initial F1 hybrid impossible. Recently, a naturally occurring strain of D. simulans has been discovered which rescues the sterility defect of hybrid females in crosses with D. melanogaster. With the ability to produce both fertile and sterile hybrid females, we are now in a position to use the vast repertoire of molecular and genetic tools available in these Drosophila species to make advances in understanding the underlying genetic and developmental causes of hybrid sterility. The first aim of this research is to use a comparative developmental approach to characterize the specific defects in gametogenesis that are associated with hybrid sterility. Using this comparative approach we can answer the following questions: What is the developmental basis of female hybrid sterility and its rescue? Do sterile, unrescued hybrid females have any functional germline tissue at all? If so, what appears to be the primary defect in germline development? Is hybrid female sterility rescue complete? Is hybrid sterility rescue sex-specific? Our second aim is to map the genetic factors responsible for hybrid female sterility and its rescue. The generation of recombinants between D. simulans lines that produce either sterile or fertile hybrid females when crossed with D. melanogaster will be used to determine which gene regions are associated with the specific hybrid sterility defects characterized in t he first aim of the proposal. In conjunction with the mapping studies, a survey of additional Drosophila lines will be conducted to isolate new sterility rescue factors, paying particular attention to complementary strains of D. melanogaster which show hybrid sterility rescue. Our final aim is then to take advantage of hybrid sterility rescue in crosses between D. melanogaster and D. simulans to introduce genetic material from one species into the other to test specific hypotheses about how genes affecting gametogenesis have diverged between these two species.