06/04/2025
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This study looks at the remarkable reproduction strategy of Corydoradinae catfish, characterised by a fertilization mode known as s***m drinking. With this fertilization mode, the female ingests the s***matozoa by attaching her mouth to the a**l region of the male during courtship. Thereafter, the s***m pass through the gastrointestinal tract and get released from the general excretory pore of the female. The s***m then reach an external place between the pelvic fins and pe*****te the ovulated eggs stored there, which is a form of in vitro fertilization.
Open-access - https://journals.biologists.com/jeb/article/228/9/jeb250293/367961
The T-spawning position is well known among Cory keepers, but less so the process of fertilisation, as this paper demonstrates the female produces proteins that essentially "stuns and shields" ingested s***m as it passes through her gastrointestinal tract.
This paper refers to the bronze cory as ๐ถ๐๐๐ฆ๐๐๐๐๐ ๐๐๐๐๐ข๐ , rather than its current name ๐๐ ๐ก๐๐๐๐๐ ๐ก๐๐ ๐๐๐๐๐.
๐ฅ๐ฒ๐๐ฒ๐ฎ๐ฟ๐ฐ๐ต ๐ง๐ถ๐๐น๐ฒ
Seminal vesicle protein caCA12 in ๐ถ๐๐๐ฆ๐๐๐๐๐ ๐๐๐๐๐ข๐ inhibits s***m motility for s***m drinking
๐๐ถ๐๐ฎ๐๐ถ๐ผ๐ป
Junki Yoshida, Maho Yamamoto, Junki Kamiya, Akinaga Kondo, Yukihito Sakaguchi, Nanami Morino, Takako Saito, Masanori Kohda, Satoshi Awata, Ban Sato, Kenji Miyado, Natsuko Kawano; Seminal vesicle protein caCA12 in ๐ถ๐๐๐ฆ๐๐๐๐๐ ๐๐๐๐๐ข๐ inhibits s***m motility for s***m drinking. J Exp Biol 1 May 2025; 228 (9): jeb250293. doi: https://doi.org/10.1242/jeb.250293
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Seminal vesicle (SV) secretions enhance fertilization by regulating s***m motility and fertilization capacity, and by forming plugs that prevent mating with other males. Although SVs are rare in teleosts, certain species, such as ๐ถ๐๐๐ฆ๐๐๐๐๐ ๐ ๐๐., do possess them. In ๐ถ๐๐๐ฆ๐๐๐๐๐ ๐ ๐๐. and other species that exhibit s***m drinking or related behaviors, females attach their mouths to the males' ge***al pore to ingest semen, a reproductive behavior known as s***m drinking. However, the major proteins and functions of seminal vesicle fluid (SVF) in ๐ถ๐๐๐ฆ๐๐๐๐๐ remain unidentified.
This study aimed to identify the SVF proteins in ๐ถ๐๐๐ฆ๐๐๐๐๐ ๐๐๐๐๐ข๐ 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. S***m motility was strongly suppressed in the presence of the SVF. We identified three SVF proteins โ alpha-2-macroglobulin (A*M), carbonic anhydrase 12 (CA12) and lymphocyte antigen 6 (Ly6) โ through RNA sequencing (RNA-Seq), LC-MS/MS and amino acid sequencing. Additionally, we found that the identified CA12, termed โcaCA12,โ 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 s***m motility. The identified SVF proteins, including caCA12, may play a role in keeping s***m in an immotile state until they are close to the female ova, facilitating the remarkable s***m drinking reproductive process observed in ๐ถ. ๐๐๐๐๐ข๐ .
๐ฃ๐ต๐ผ๐๐ผ ๐๐ฟ๐ฒ๐ฑ๐ถ๐
Left - Albino ๐๐ ๐ก๐๐๐๐๐ ๐ก๐๐ ๐๐๐๐๐ spawning. By Docmarius - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=37480430
Right top - Mechanism showing the role of SV proteins in s***m drinking. In SVF, caCA12 inhibits s***m motility immediately after male ej*******on and within the gastrointestinal tract, preventing s***m from expending energy prematurely. The viscosity of SVF, combined with the enzymatic activity of caCA12, acts as a barrier, preventing s***m from diffusing into the gastrointestinal tract and so protecting s***m from digestion. After passing through the gastrointestinal tract, caCA12 is digested or removed from the s***m surface, allowing s***m to regain motility and move towards the eggs. A*M, alpha-2-macroglobulin; Ly6/uPAR, lymphocyte antigen 6/urokinase-type plasminogen activator receptor.
Right bottom - Male reproductive organs related to reproduction and the function of seminal vesicle fluid (SVF) in ๐ถ๐๐๐ฆ๐๐๐๐๐ ๐๐๐๐๐ข๐ . (A) Photograph of an adult male ๐ถ. ๐๐๐๐๐ข๐ . Scale bar: 1 cm. (B) Illustration of s***m drinking, a reproductive behavior in ๐ถ๐๐๐ฆ๐๐๐๐๐ ๐ ๐๐. The white duct in the female is the gastrointestinal tract, and the upper yellow sac is the o***y. In s***m drinking, ๐ถ๐๐๐ฆ๐๐๐๐๐ s***m migrate through the female gastrointestinal duct and fertilize the eggs at an external place between the pelvic fins. (C) Morphology of the male reproductive organ of ๐ถ๐๐๐ฆ๐๐๐๐๐ . Photograph (left) and diagram (right) of the male reproductive organ. Dashed lines on the diagram indicate the histological location of the te**is and seminal vesicle (SV). Scale bar: 2 mm. (D) Hematoxylin and eosin (HE) staining of the te**is. Scale bar: 200 ยตm. Yellow arrowhead indicates s***matozoa in a cyst. (E) HE staining of the seminal vesicles. Scale bar: 200 ยตm. White arrowhead indicates secretory epithelium and asterisk indicates eosin-positive SVF inside the epithelium. (F) ๐ถ๐๐๐ฆ๐๐๐๐๐ s***m motility in Hepes buffer, PBS buffer or SVF at different dilutions. S***m motility values were normalized to the number of motile s***matozoa in the control condition using distilled water (DW). Independent experiments were performed using s***matozoa collected from different ๐ถ๐๐๐ฆ๐๐๐๐๐ males. PBS solution was undiluted (100% PBS), or diluted to 75% PBS and 50% PBS with DW; 50% SVF in DW was undiluted (50% SVF), or diluted to 5% SVF, 0.5% SVF, 0.05% SVF, 0.005% SVF and 0.0005% SVF. Data are means+s.d. Numbers in parentheses are number of male ๐ถ. ๐๐๐๐๐ข๐ examined. Unpaired two-tailed Student's t-test was conducted (*P
