Yoshida Junki, Yamamoto Maho, Kamiya Junki, Kondo Akinaga, Sakaguchi Yukihito, Morino Nanami, Saito Takako, Kohda Masanori, Awata Satoshi, Sato Ban, Miyado Kenji, Kawano Natsuko
Department of Life Sciences, School of Agriculture, Meiji University, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan.
Organization for the Strategic Coordination of Research and Intellectual Properties, Meiji University, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan.
J Exp Biol. 2025 May 1;228(9). doi: 10.1242/jeb.250293. Epub 2025 May 15.
Seminal vesicle (SV) secretions enhance fertilization by regulating sperm motility and fertilization capacity, and by forming plugs that prevent mating with other males. Although SVs are rare in teleosts, certain species, such as Corydoras spp., do possess them. In Corydoras spp. and other species that exhibit sperm drinking or related behaviors, females attach their mouths to the males' genital pore to ingest semen, a reproductive behavior known as sperm drinking. However, the major proteins and functions of seminal vesicle fluid (SVF) in Corydoras remain unidentified. This study aimed to identify the SVF proteins in Corydoras aeneus and clarify the functions of the identified major SVF proteins. The SVF of this species was found to be highly viscous with a high protein concentration. Sperm motility was strongly suppressed in the presence of the SVF. We identified three SVF proteins - alpha-2-macroglobulin (A2M), carbonic anhydrase 12 (CA12) and lymphocyte antigen 6 (Ly6) - through RNA sequencing (RNA-Seq), LC-MS/MS and amino acid sequencing. Additionally, we found that the identified CA12, termed 'caCA12,' was degraded into about 10 kDa and 33 kDa polypeptides containing the CA domain. The 33 kDa polypeptide with the CA domain was found to inhibit sperm motility. The identified SVF proteins, including caCA12, may play a role in keeping sperm in an immotile state until they are close to the female ova, facilitating the remarkable sperm drinking reproductive process observed in C. aeneus.
精囊（SV）分泌物通过调节精子活力和受精能力，以及形成防止与其他雄性交配的栓子来增强受精。虽然硬骨鱼中的精囊很少见，但某些物种，如兵鲶属物种，确实拥有精囊。在兵鲶属物种和其他表现出吸食精子或相关行为的物种中，雌性会将嘴贴在雄性的生殖孔上摄取精液，这种生殖行为被称为吸食精子。然而，兵鲶属精囊液（SVF）中的主要蛋白质及其功能仍未明确。本研究旨在鉴定青铜兵鲶的SVF蛋白质，并阐明所鉴定的主要SVF蛋白质的功能。发现该物种的SVF具有高粘性和高蛋白浓度。在SVF存在的情况下，精子活力受到强烈抑制。我们通过RNA测序（RNA-Seq）、液相色谱-串联质谱（LC-MS/MS）和氨基酸测序鉴定了三种SVF蛋白质——α-2-巨球蛋白（A2M）、碳酸酐酶12（CA12）和淋巴细胞抗原6（Ly6）。此外，我们发现所鉴定的CA12（称为“caCA12”）被降解为含有CA结构域的约10 kDa和33 kDa的多肽。发现含有CA结构域的33 kDa多肽可抑制精子活力。所鉴定的SVF蛋白质，包括caCA12，可能在精子接近雌性卵子之前使其保持不活动状态，从而促进在青铜兵鲶中观察到的显著的吸食精子生殖过程中发挥作用。
