Guay Sara Y, Patel Prajal H, Thomalla Jonathon M, McDermott Kerry L, O'Toole Jillian M, Arnold Sarah E, Obrycki Sarah J, Wolfner Mariana F, Findlay Geoffrey D
Department of Biology, College of the Holy Cross, Worcester, MA 01610.
Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853.
bioRxiv. 2024 Dec 14:2024.08.08.607187. doi: 10.1101/2024.08.08.607187.
While spermatogenesis has been extensively characterized in the model system, very little is known about the genes required for fly sperm entry into eggs. We identified a lineage-specific gene, which we named (), that is required for efficient fertilization. Males that do not express produce and transfer sperm that are stored normally in females, but sperm from these males enter eggs with severely reduced efficiency. Using a tagged transgenic rescue construct, we observed that the KJ protein localizes around the edge of the nucleus at various stages of spermatogenesis but is undetectable in mature sperm. These data suggest that exerts an effect on sperm development, the loss of which results in reduced fertilization ability. Interestingly, KJ protein lacks detectable sequence similarity to any other known protein, suggesting that could be a lineage-specific orphan gene. While previous bioinformatic analyses indicated that was restricted to the group of , we identified putative orthologs with conserved synteny, male-biased expression, and predicted protein features across the genus, as well as likely instances of gene loss in some lineages. Thus, was likely present in the common ancestor and subsequently evolved an essential role in fertility in . Our results demonstrate a new aspect of male reproduction that has been shaped by a lineage-specific gene and provide a molecular foothold for further investigating the mechanism of sperm entry into eggs in .
虽然精子发生在该模型系统中已得到广泛表征，但对于果蝇精子进入卵子所需的基因却知之甚少。我们鉴定出了一个谱系特异性基因，我们将其命名为（），它是高效受精所必需的。不表达该基因的雄性产生并转移精子，这些精子在雌性体内能正常储存，但来自这些雄性的精子进入卵子的效率会大幅降低。使用带有标签的转基因拯救构建体，我们观察到KJ蛋白在精子发生的各个阶段都定位于细胞核边缘，但在成熟精子中检测不到。这些数据表明该基因对精子发育有影响，其缺失会导致受精能力下降。有趣的是，KJ蛋白与任何其他已知蛋白都没有可检测到的序列相似性，这表明该基因可能是一个谱系特异性孤儿基因。虽然先前的生物信息学分析表明该基因仅限于某一群体，但我们在整个属中鉴定出了具有保守共线性、雄性偏向表达和预测蛋白特征的假定直系同源物，以及一些谱系中可能的基因丢失情况。因此，该基因可能存在于共同祖先中，随后在某一物种中在生育力方面进化出了重要作用。我们的结果展示了雄性繁殖的一个新方面，它是由一个谱系特异性基因塑造的，并为进一步研究某一物种中精子进入卵子的机制提供了分子立足点。
