Effects of Different Cryoprotectants on Cryopreservation of Sperm from Noble Scallop Mimachlamys nobilis

In cryopreservation technology, the choice of cryoprotectant plays a crucial role in cell survival and function. Different types of cryoprotectants, each with unique protective mechanisms, mitigate cellular damage from ice crystal formation during freezing. This study investigated the effects of different types and concentrations of cryoprotectants on the cryopreservation efficacy of noble scallop Mimachlamys nobilis sperm. Six cryoprotectants were tested, including four permeable cryoprotectants (dimethyl sulfoxide (DMSO), ethylene glycerol (EG), propylene glycerol (PG), methanol (MET)) and two non-permeable cryoprotectants (trehalose (TRE), fetal bovine serum (FBS)). The results showed that permeable cryoprotectants, which penetrate the cell membrane, regulate the osmotic pressure inside and outside cells to reduce dehydration damage. Among them, 10% DMSO provided the best protection, significantly preserving sperm motility, velocity, and morphology. Non-permeable cryoprotectants, although unable to penetrate cells, stabilized the extracellular environment at higher concentrations (such as FBS). Additionally, MET and FBS exhibited enhanced protective effects with increasing concentration, indicating their potential in reducing sperm structural damage at higher concentrations. Morphological observations indicated that freezing caused varying degrees of structural damage to sperm, with flagellar integrity being crucial for motility. Overall, selecting an appropriate cryoprotectant and concentration is essential for the efficient cryopreservation of M. nobilis sperm, providing a valuable reference for conserving germplasm resources of marine species.