Responses of transcriptomic profile to cryopreservation in dwarf surfclam (Mulinia lateralis) sperm

Non-programmable sperm cryopreservation technique has been established for many farmed bivalve species, however, the quality of post-thaw sperm remains substantially variable in practical applications. Although cryodamage to sperm has been investigated cellularly and physiologically, the underpinning molecular mechanism is still not fully elucidated. The dwarf surfclams (Mulinia lateralis) have been used as a model species for bivalves across multiple biological studies. In this study, this species was utilized to investigate the changes in transcriptomic profiles of post-thaw sperm through RNA sequencing (RNA-seq). The results identified 805 differentially expressed transcripts (DETs) between fresh and cryopreserved sperm. The enrichment network analysis of the significantly altered Gene Ontology terms indicated that theses DETs were mainly involved in the structure or functions of cellular membrane, motility, cytoskeleton, mitochondria, immunity and proteasome. Further pathway enrichment analysis revealed that the genes transferred from these DETs were predominantly involved in mitogen-activated protein kinase (MAPK) signaling, insulin signaling, proteasome and oxidative phosphorylation pathways. The findings in this study could offer valuable insights in sperm cryodamage at molecular level, which can therefore be applied to further improve sperm cryopreservation technique for both dwarf surfclam and commercially important bivalve species.