mRNA Translation and Germline Evolution in Caenorhabditis

进化生物学面临的最大挑战之一，就是要理解新的解剖学特征是如何在不破坏整体发展连贯性的前提下出现的。由于许多控制发育的基因是广泛保守的，因此这一过程必须融合古老的成分和新的特征，例如物种特异性基因或基因之间的调控联系。这项研究探讨了一个生态学上重要的新奇，它在小杆线虫中反复进化--自我受精的两性畸形。自我繁殖进化的关键一步是雌性蠕虫产生有限数量精子的能力，这使它们变成雌雄同体。雌雄同体精子的产生是由存在于生殖细胞（配子的前体）中的信使RNA结合蛋白（RBP）调节的。这些RBP之一，GLD-1，是一种古老的，缓慢进化的蛋白质，调节数百种靶mRNA。 GLD-1在两个不同物种中独立参与雌雄同体生殖系的性别决定。elegans和C.布里格塞然而，在C. elegans中GLD-1促进精子命运，而C.这种矛盾现象可以通过GLD-1蛋白辅因子的物种特异性进化和GLD-1结合的mRNA分子序列的变化来解释。该项目将与几个小杆线虫物种合作，系统地研究辅因子和mRNA序列的变化如何改变GLD-1活性的背景，以允许出现新的生殖策略。更一般地说，这项研究将有助于揭示旧分子如何承担新的角色，从而在生物组织的分子和有机体尺度上将进化联系起来。 我们将利用这个项目来帮助当地的高中教师了解科学研究的好处，这样他们就可以把这些教训传达给他们的班级。

One of the grand challenges of evolutionary biology is to understand how new anatomical features emerge without disrupting the overall coherence of development. Because many genes that control development are widely conserved, the process must blend both ancient components and new features, such as species-specific genes or regulatory connections between genes. This research examines an ecologically important novelty that has evolved repeatedly in Caenorhabditis nematodes--self-fertile hermaphroditism. A key step in the evolution of self-fertility was the ability of otherwise female worms to produce a limited number of sperm, which turned them into hermaphrodites. Hermaphrodite sperm production is regulated by messenger RNA-binding proteins (RBPs) present in the germ cells (the precursors of gametes). One of these RBPs, GLD-1, is an ancient, slow-evolving protein that regulates hundreds of target mRNAs. GLD-1 was coopted into hermaphrodite germ line sex determination independently in two different species, C. elegans and C. briggsae. However, in C. elegans GLD-1 promotes sperm fate, whereas in C. briggsae GLD-1 represses it. This paradox is explained by the species-specific evolution of GLD-1 protein cofactors and by changes in the sequences of the mRNA molecules that GLD-1 binds. This project will work with several Caenorhabditis species to systematically examine how both cofactors and mRNA sequence changes alter the context of GLD-1 activity to allow the emergence of a new reproductive strategy. More generally, this research will help reveal how old molecules can take on new roles, thereby linking evolution at the molecular and organismal scales of biological organization. We will use this project to help local high school teachers understand the excitment of scientific research so they can convey these lessons to their classes.