The Sperm Laboratory, College of Life Sciences, Zhejiang University, Hangzhou, China.
PLoS One. 2010 Sep 14;5(9):e12738. doi: 10.1371/journal.pone.0012738.
The Chinese mitten crab Eriocheir sinensis belongs to the Class Crustacea, Decapoda, Brachyura. The spermatozoon of this species is of aflagellated type, it has a spherical acrosome surrounded by the cup-shaped nucleus, which are unique to brachyurans. For the past several decades, studies on the spermatogenesis of the mitten crab mainly focus on the morphology. Compared with the extensive study of molecular mechanism of spermatogenesis in mammals, relatively less information is available in crustacean species. Myosin Va, a member of Class V myosin, has been implicated in acrosome biogenesis and vesicle transport during spermatogenesis in mammals. In the present study we demonstrate the expression and cellular localization of myosin Va during spermatogenesis in E. sinensis.
METHODOLOGY/PRINCIPAL FINDINGS: Western blot demonstrated that myosin Va is expressed during spermatogenesis. Immunocytochemical and ultrastructural analyses showed that myosin Va mainly localizes in the cytoplasm in spermatocytes. At the early stage of spermiogenesis, myosin Va binds to the endoplasmic reticulum vesicle (EV) and proacrosomal granule (PG). Subsequently, myosin Va localizes within the proacrosomal vesicle (PV) formed by PG and EV fusion and locates in the membrane complex (MC) at the mid spermatid stage. At the late spermatid stage, myosin Va is associated with the shaping nucleus and mitochondria. In mature spermatozoon, myosin Va predominates in acrosomal tubule (AT) and nucleus.
CONCLUSIONS/SIGNIFICANCE: Our study demonstrates that myosin Va may be involved in acrosome biogenesis and nuclear morphogenesis during spermatogenesis in E. sinensis. Considering the distribution and molecular characteristics of myosin Va, we also propose a hypothesis of AT formation in this species. It is the first time to uncover the role of myosin Va in crustacean spermatogenesis.
中华绒螯蟹（Eriocheir sinensis）属于甲壳纲、十足目、短尾亚目。该物种的精子为无鞭毛型，具有被杯状核包围的球形顶体，这是短尾亚目所特有的。在过去的几十年里，中华绒螯蟹的精子发生研究主要集中在形态学上。与哺乳动物精子发生的分子机制的广泛研究相比，甲壳类动物的信息相对较少。肌球蛋白 Va 属于肌球蛋白 V 类，在哺乳动物的顶体发生和囊泡运输中起作用。本研究旨在证明肌球蛋白 Va 在中华绒螯蟹精子发生过程中的表达和细胞定位。
方法/主要发现：Western blot 表明肌球蛋白 Va 在精子发生过程中表达。免疫细胞化学和超微结构分析表明，肌球蛋白 Va 主要定位于精母细胞的细胞质中。在精子发生的早期，肌球蛋白 Va 与内质网囊泡（EV）和前顶体颗粒（PG）结合。随后，肌球蛋白 Va 定位于由 PG 和 EV 融合形成的前顶体囊泡（PV）中，并在中精细胞阶段位于膜复合物（MC）中。在晚期精细胞阶段，肌球蛋白 Va 与形成的核和线粒体相关。在成熟精子中，肌球蛋白 Va 主要存在于顶体小管（AT）和核中。
结论/意义：本研究表明，肌球蛋白 Va 可能参与中华绒螯蟹精子发生中的顶体发生和核形态发生。考虑到肌球蛋白 Va 的分布和分子特征，我们还提出了该物种 AT 形成的假说。这是首次揭示肌球蛋白 Va 在甲壳类动物精子发生中的作用。
