Some aquatic invertebrates contain free D-alanine. We previously showed copious amounts of free D-glutamate, a novel D-amino acid, in the tissue of the male reproductive organs of Marsupenaeus japonicus. Herein, we clarified the distribution and potential role of D-glutamate and D-alanine in male reproductive tissues, namely the testis, vas deferens, and seminal receptacle at different growth stages of M. japonicus. The percentage of D-glutamate to total glutamate was over 50% in these tissues. In particular, the content of D-glutamate was the most abundant in the vas deferens, the ratio of D-glutamate to total glutamate was approximately 80%. In contrast, D-alanine content was the lowest in the vas deferens among these tissues. D-Glutamate content was the highest when the prawn weighed 12 g, indicating that D-glutamate is actively synthesized in the younger stage. Our findings suggest that D-glutamate plays an important role in the reproductive functions of M. japonicus.

中文翻译：

---

D-谷氨酸（一种在动物体内鉴定出的新型 D-氨基酸）在雄性日本对虾生殖组织中的分布和作用

一些水生无脊椎动物含有游离的 D-丙氨酸。我们之前在日本袋对虾的雄性生殖器官组织中发现了大量的游离 D-谷氨酸（一种新型 D-氨基酸）。在此，我们阐明了D-谷氨酸和D-丙氨酸在刺参不同生长阶段的雄性生殖组织（即睾丸、输精管和储精器）中的分布和潜在作用。这些组织中D-谷氨酸占总谷氨酸的百分比超过50%。尤其是输精管中D-谷氨酸含量最为丰富，D-谷氨酸占总谷氨酸的比例约为80%。相比之下，这些组织中输精管中的 D-丙氨酸含量最低。当对虾体重12克时，D-谷氨酸含量最高，表明D-谷氨酸在幼虾阶段合成活跃。我们的研究结果表明，D-谷氨酸在日本刺参的繁殖功能中发挥着重要作用。