Protein profile of Dabry's sturgeon (Acipenser dabryanus) spermatozoa and relationship to sperm quality.

Knowledge of conditions affecting sperm quality is essential for efficient culture of fish for commercial purposes and conservation of species. Two-dimensional gel electrophoresis and matrix-assisted laser desorption/ionization time of flight mass spectrometry were used to characterize the proteomic profile of Acipenser dabryanus spermatozoa relative to motility and fertilization capacity. There were differential amounts of protein in 313 spots in spermatozoa of males classified to have relatively greater or lesser spermatozoa quality. The functions of 43 of 50 selected proteins were identified. The proteins in 14 spots were involved in metabolism, and of these, proteins in 11 spots were highly abundant in spermatozoa of males categorized to have spermatozoa of greater quality, including pyruvate kinase, enolase B, phosphoglycerate kinase, lactate dehydrogenase, cytosolic malate dehydrogenase, brain creatine kinase b, Ckmb protein, and nucleoside diphosphate kinase. The proteins involved in mechanics of flagellum movement were identified, including the dynein intermediate chain, radial spoke head 1 homolog; ropporin-1-like, Bardet-Biedl syndrome 5, ADP-ribosylation factor-like protein 3, tektin-4, gamma-actin, and tubulin cytoskeleton proteins to be differentially abundant in spermatozoa that were classified relatively greater or lesser quality. Heat shock proteins, copper/zinc superoxide dismutase and peroxiredoxins, which are involved in stress response were of differential abundance in spermatozoa from males with spermatozoa in the two different classification groups. Proteins were also detected that are involved in protein folding and binding, or hydrolase activity. The results are valuable for the prediction of sperm quality and for reproduction management in A. dabryanus and other threatened species.

Geranylgeranylacetone induction of HSP90α exerts cryoprotective effect on Acipenser sinensis sperm.

Heat Shock Protein 90 (HSP90) is a fertility-associated protein, the expression of which positively correlates with sperm quality in many species. Geranylgeranylacetone (GGA) is reported to induce expression of HSP90. The present study aimed to investigate whether GGA induced expression of HSP90 in Acipenser sinensis sperm to exert a cryoprotective effect. Sperm from five male A. sinensis was combined with extender containing 20 mmol/L tris pH = 8.1, 10% v/v methanol, 2-5 mmol/L KCl, 15 mmol/L lactose, and 15 mmol/L trehalose, with GGA at 0, 14, 67, 135, 673, 1346, or 6731 µmol/L. After cryopreservation and thawing, the percentage of motile spermatozoa, spermatozoon curvilinear velocity (VCL), straight-line velocity (VSL), average path velocity (VAP), acrosome integrity, and membrane integrity, as well as fertility were evaluated. Sperm quality increased with the increase of GGA to 673 µmol/L, but decreased at higher concentrations. Expression levels of HSP90α were detected by Western blot in sperm frozen with GGA at 673 µmol/L (highest obtained sperm quality), 6731 µmol/L (highest GGA concentration), and a control without GGA. The expression of HSP90α increased with the increase in GGA, with lowest expression observed in the control. GGA was found to induce increase of HSP90α, and this increase was associated with higher quality cryopreserved sperm at concentrations ≤673 µmol/L. This research suggests a viable technique to increase the quality of cryopreserved A. sinensis sperm by adding GGA to induce expression of HSP90α.