The characterization of gene expression in gametes has advanced our understanding of the molecular basis for ecological variation in reproductive success and the evolution of reproductive isolation. These advances are especially significant for ecologically important keystone predators such as the coral-eating crown-of-thorns sea stars (COTS, Acanthaster) which are the most influential predator species in Indo-Pacific coral reef ecosystems and the focus of intensive management efforts. We used RNA-seq and transcriptome assemblies to characterize the expression of genes in mature COTS gonads. We described the sequence and domain organization of eight genes with sex-specific expression and well known functions in fertilization in other echinoderms. We found unexpected expression of genes in one ovary transcriptome that are characteristic of males and sperm, including genes that encode the sperm-specific guanylate cyclase receptor for an egg pheromone, and the sperm acrosomal protein bindin. In a reassembly of previously published RNA-seq data from COTS testes, we found a complementary pattern: strong expression of four genes that are otherwise well known to encode egg-specific fertilization proteins, including the egg receptor for bindin (EBR1) and the acrosome reaction-inducing substance in the egg coat (ARIS1, ARIS2, ARIS3). We also found histological evidence of both eggs and sperm developing in the same gonad in several COTS individuals from a parallel study. These results suggest the occurrence of hermaphrodites, and the potential for reproductive assurance via self-fertilization. Our findings have implications for management of COTS populations, especially in consideration of the large size and massive fecundity of these sea stars.

中文翻译：

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受精基因在荆棘冠棘Acanthaster中的非特异性表达cf. solaris：珊瑚礁捕食者中雌雄同体的意外证据。

配子中基因表达的表征使我们对生殖成功中生态变异和生殖分离进化的分子基础有了更深入的了解。这些进展对于具有生态重要性的基石捕食者尤其重要，例如食珊瑚的荆棘王冠海星（COTS，Acanthaster），它们是印度太平洋珊瑚礁生态系统中最具影响力的捕食物种，也是集约化管理工作重点。我们使用RNA-seq和转录组装配来表征成熟的COTS性腺中基因的表达。我们描述了八个具有性别特异性表达和其他棘皮动物受精功能的基因的序列和结构域组织。我们在一个卵巢转录组中发现了意想不到的基因表达，该基因是男性和精子的特征，包括编码卵信息素的精子特异性鸟苷酸环化酶受体和精子顶体蛋白结合蛋白的基因。在重新整理来自COTS睾丸的先前发布的RNA-seq数据的过程中，我们发现了一种互补的模式：四个众所周知表达编码卵特异性受精蛋白的基因的强表达，包括结合蛋白（EBR1）的卵受体和顶体蛋壳中的反应诱导物质（ARIS1，ARIS2，ARIS3）。我们还从一项平行研究中发现，在多个COTS个体中，卵和精子在同一性腺中发育的组织学证据。这些结果表明雌雄同体的发生，以及通过自我受精获得生殖保证的潜力。