Disaccharide combinations and the expression of enolase3 and plasma membrane Ca 2+ ATP ase isoform in sturgeon sperm cryopreservation

Contents Acipenser sinensis and Acipenser dabryanus are critically endangered species, so germplasm conservation via cryopreservation of sperm is necessary. Disaccharides can act as membrane‐impermeable cryoprotectants, and enolase3 ( ENO 3) and plasma membrane Ca 2+ ATP ase isoform ( PMCA 2) are proteins associated with sperm quality. We considered seven characteristics of sperm quality in cultured brood stock from A. sinensis and A. dabryanus . We tested use of sucrose or trehalose alone and in combination at different concentrations for cryopreservation of A. dabryanus sperm. A low concentration of sucrose plus trehalose (S 15 T 15 ) was optimal. Mixing of the extender with sucrose, lactose, or trehalose alone or with pairwise mixtures revealed that a mixture of lactose and trehalose (L 15 T 15 ) gave the best results for both A. sinensis and A. dabryanus . Enolase3 and PMCA 2 expression levels were measured in cryopreserved A. sinensis sperm via Western blotting. Relative ENO 3 and PMCA 2 expression levels were examined, and the relationship between disaccharide composition, sperm quality and protein expression was explored in A. sinensis . The results showed that relative ENO 3 and PMCA 2 expression levels were the highest at L 15 T 15 in cryopreserved A. sinensis sperm. There were significant positive correlations between ENO 3 expression and percentage membrane integrity, and between PMCA 2 expression and sperm motility parameters (percentage of motile sperm, curvilinear velocity, straight‐line velocity and average path velocity; p < .05 ) in cryopreserved A. sinensis sperm. Our results indicate the optimal disaccharide combination and concentrations for cryopreservation of A. sinensis and A. dabryanus sperm and suggest that ENO 3 and PMCA 2 expression levels could serve as a valuable indicator of sperm quality in A. sinensis .