Cryopreservation of Noble Scallop Mimachlamys nobilis sperm: Optimization study of cooling rate and thawing temperature

In marine biology reproduction research, the cryopreservation of sperm is a crucial area, especially for economically valuable species. Effective freezing techniques help maintain genetic diversity and support sustainable development in aquaculture. This study examined the effects of freezing protocols and thawing methods on the cryopreservation of Mimachlamys nobilis sperm. Experimental results indicated that a cooling rate of 5 °C/min and an equilibration time of 5 minutes were the most suitable conditions for maintaining the structural and functional integrity of the sperm. Comparisons of different thawing temperatures showed that 38 °C provided the best results, minimizing ice recrystallization and cellular damage. Additionally, it was found that a 10 % concentration of DMSO effectively balanced protection and cytotoxicity, maintaining sperm viability and motility. Transmission electron microscopy further revealed the impact of freezing conditions on sperm, including damage to the plasma membrane, dissolution, blurring and swelling of the acrosome and mitochondria, and cristae fragmentation and loss. This study emphasizes the importance of optimizing freezing and thawing protocols and accurately controlling cryoprotectant concentration, providing key insights for the effective long-term preservation of M.nobilis sperm. This is significant for the conservation of marine organisms and aquaculture. • A 5 °C/min cooling rate and 5-min balance time optimize M. nobilis sperm integrity during cryopreservation. • Thawing at 38 °C minimizes ice recrystallization, enhancing M. nobilis sperm survival and vitality. • A 10% DMSO concentration provides optimal protection for M. nobilis sperm, balancing survival and toxicity. • Freeze-thawing causes plasma membrane damage, acrosome blurring, and mitochondrial swelling in M. nobilis sperm.