Adaptive Protein Evolution of the Drosophila Germline Stem Cell Gene Bag of Marbles

项目总结 动物含有少量的生殖系干细胞(GSCs)，这是制造精子或卵子所必需的。 分裂干细胞自我更新或分化的决定，以及早期GSC分裂的调节 是发展中最关键的几个过程。对果蝇黑腹果蝇的研究表明， 确定了许多与GSC维持和分化的细胞信号有关的关键基因。我们 已经表明，大理石基因袋(Bam)是GSC分化的关键“开关”，它正在适应性地进化。 在黑腹夜蛾、拟态夜蛾、雅库巴夜蛾中氨基酸替换显著过剩，但在6种动物中没有。 其他相关物种。在我们当前的资助期内，我们在以下方面产生了新的bam零突变 测序了黑腹夜蛾、拟态夜蛾、雅库巴夜蛾、泰西耶里夜蛾和花斑夜蛾的基因组，以进行测试 功能守恒。这些让我们能够证明，令人惊讶的是，不像黑腹蛇， 铁皮石杉雌性GSC分化不需要BAM，雄性GSC分化也不需要BAM 在D.teissieri和D.我们已经证明，感染不同菌株的细胞内 内共生沃尔巴克氏杆菌对巴姆所特有的生育缺陷的挽救程度各不相同。 低形体。该提案侧重于确定观察到的功能和进化后果 Bam基因的序列多样性及其在GSC功能中的作用假说之间的区分 已经被选择用于新的功能，而不是假设bam和W.pipientis之间的相互作用具有 是推动bam变革的进化力量。这包括生成和分析小说bam 以及这些新亚态与Intra之间的相互作用 和种间沃尔巴克氏菌株。我们将对白纹伊蚊的bam营救进行rna-seq研究。我们 正在开发一种计算模型来生成可通过实验测试的序列预测 管圆线虫和GSC基因相互作用的几种机制下的多样性。最后，我们会 从功能上评价黑腹小卷蛾和黑腹小卷蛾之间bam蛋白序列的进化多样性。 SIMANS，以及D。 Tissieri与其近亲D.Yakuba进行了比较。我们所学到的将对我们的 了解在不同物种的发育过程中GSCs是如何受到调控的，这种关键 发育功能可以进化，以及它们如何由于突变和相互作用而误调节 生殖系寄生虫可能导致不孕、生殖系癌症和生殖隔离。

PROJECT SUMMARY Animals contain a small number of germline stem cells (GSCs) that are essential for making sperm or eggs. The decision for a dividing stem cell to renew itself or to differentiate, and the regulation of early GSC divisions are some of the most critical processes in development. Studies in the fruit fly, Drosophila melanogaster, have identified many of the key genes involved in the cellular signaling for GSC maintenance and differentiation. We have shown that the gene bag of marbles (bam), the key “switch” for GSC differentiation, is adaptively evolving with a dramatic excess of amino acid substitutions in D. melanogaster, D. simulans, D. yakuba but not in six other related species. During our current funding period we have generated new bam null mutations in sequenced genomes of D. melanogaster, D. simulans, D. yakuba, D. teissieri, and D. ananassae to test for conservation of function. These have allowed us to demonstrate that surprisingly unlike in D. melanogaster, bam is not required for female GSC differentiation in D. teissieri nor is it required for male GSC differentiation in D. teissieri and D. ananassae. We have shown that infection with different strains of the intracellular endosymbiont Wolbachia pipientis vary in their degree of rescue of the fertility defects characteristic of the bam hypomorph. This proposal focuses on identifying the functional and evolutionary consequences of observed sequence diversification at bam and discriminating between the hypothesis that bam’s role in GSC function has been selected for new functions, vs the hypothesis that interactions between bam and W. pipientis has been the evolutionary force driving changes at bam. This includes generating and analyzing novel bam hypomorphs in D. melanogaster and D. simulans, and testing interactions of these new hypomorphs with intra and interspecific Wolbachia strains. We will carry out RNA-seq studies of the bam rescue by W. pipientis. We are developing a computational model to generate experimentally testable predictions of sequence diversification under several mechanisms of interaction between W. pipientis and GSC genes. Finally, we will functionally evaluate evolutionary diversification of the bam protein sequence between D. melanogaster and D. simulans, and the loss of the requirement for bam for female and male gametogenesis and fertility in D. teissieri compared to its close relative D. yakuba. What we learn will contribute significantly to our understanding of how GSCs are regulated during development in diverse species, how such critical developmental functions can evolve, and how their mis-regulation due to mutation and interaction with germline parasites can lead to infertility, germline cancers, and reproductive isolation.