The Genetics of Reproductive Isolation: Co-Evolution, Polymorphism and Functional Differentiation of Gamete Recognition Loci in Sea Urchins

了解物种如何起源一直是生物学中最重要的，但也是最困难的挑战之一。在我们对物种起源的理解中，最大的差距之一是伴随着生殖隔离的遗传变化。这一提议描述了在这样一个新兴的模型系统中的新实验：在最近分化的棘海胆属的超可变配子附着基因。由于精子无法与其他物种的卵子融合，这些物种在生殖上被隔离。我们之前的工作表明，精子附着蛋白结合蛋白在棘球蚴物种之间存在很大的差异，并且在物种内部存在很大的差异。由于对海胆受精分子生物学的积极研究，我们现在也可以检查卵子受体的基因，并首次研究参与生殖隔离的相互作用基因的共同进化。我们将通过对Enhinometra中的卵子受体基因进行测序，并将结果与我们现有的结合蛋白序列进行比较，来检验结合蛋白/受体的共同进化。4种印度-太平洋棘球蚴的cDNA序列将用于测试在binding中观察到的模式。这些结果将使我们能够理解与定义物种边界的机制密切相关的蛋白质的共同进化。我们的研究对受精机制的基础研究以及卵子和精子如何成功地相互识别也很重要。

9510407 PALUMBI Understanding how species originate has been one of the most important, yet one of the most difficult, challenges in biology. One of the largest gaps in our understanding of the origin of species concerns the genetic changes that accompany reproductive isolation. This proposal describes new experiments in one such emerging model system: hyper-variable gamete attachment genes in recently diverged sea urchins in the genus Echinometra. These species are reproductively isolated by the failure of sperm to fuse with eggs of different species. Our prior work has shown that the sperm attachment protein bindin has diverged greatly between Echinometra species, and is extensively variable within species. Because of active work on the molecular biology of sea urchin fertilization, we can now also examine the gene for the egg receptor, and for the first time study the co-evolution of interacting genes involved in reproductive isolation. We will examine bindin/receptor co-evolution by sequencing the egg receptor gene in Enhinometra and comparing results to our existing bindin sequences. cDNA sequences of the 4 Indo-Pacific Echinometra species will be used to test for patterns observed in bindin. The results will allow us to understand the co-evolution of proteins that are closely involved in the mechanisms that define species boundaries. Our studies are also important for basic research on mechanisms of fertilization, and how egg and sperm successfully recognize one another.