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

当不同的物种杂交在一起时，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）。本研究的重点是了解黑腹果蝇和拟果蝇杂交后代杂种不育的遗传和发育基础。早期对杂交不育的分析受到了阻碍，因为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杂交之外的简单遗传分析是不可能的。近年来，人们发现了一种自然产生的拟斑天牛株系，它可以挽救与黑腹天牛杂交雌性的不育缺陷。有了产生可育和不育杂交雌性的能力，我们现在可以利用这些果蝇物种的大量分子和遗传工具，在了解杂交不育的潜在遗传和发育原因方面取得进展。本研究的第一个目的是使用比较发育方法来表征配子体发生中与杂交不育相关的特定缺陷。利用这种比较方法，我们可以回答以下问题：雌性杂交不育的发育基础是什么？不育的，未被拯救的杂交雌性有任何功能的生殖细胞组织吗？如果是这样，那么生殖细胞发育的主要缺陷是什么呢？杂交女性不育抢救完成了吗？混合性不育是否有性别特异性？我们的第二个目标是绘制导致杂交女性不育的遗传因素及其挽救。当与黑腹龙葵杂交时，产生不育或可育杂交雌性的拟马葵系之间的重组将用于确定哪些基因区域与该提议的第一个目标所描述的特定杂交不育缺陷相关。在进行图谱研究的同时，还将对其他果蝇品系进行调查，以分离出新的不育拯救因子，特别关注具有杂交不育拯救作用的黑腹果蝇互补品系。我们的最终目标是利用杂交不育拯救的优势，将一个物种的遗传物质引入另一个物种，以测试影响配子体发生的基因如何在这两个物种之间分化的特定假设。

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.