Mytilus galloprovincialis cryopreserved oocytes LC-MS/MS data

Cryopreservation of gametes offers significant potential for genetic diversity conservation and selective breeding in aquaculture. The blue mussel, Mytilus galloprovincialis, is valuable in the aquaculture industry, but declining seed availability and the need for efficient hatchery production, especially outside its natural reproductive season, make gamete cryopreservation essential. However, cryopreserving gametes, particularly oocytes from marine invertebrates, is challenging due to the balance required between cryoprotectant cytotoxicity and cell protection during freezing-thawing. This study investigates the effects of two common cryoprotectants, dimethyl sulfoxide (DMSO) and ethylene glycol (EG), on M. galloprovincialis oocytes using a monitored slow freezing (MSF) protocol. Our integrative analytical approach combined proteomics, functional, and ultrastructural analyses. Findings highlight that cryoprotectants induce significant proteomic alterations, more pronounced with DMSO than EG. These alterations are linked to oxidative stress, ineffective antioxidant response, and disruptions in meiosis restart mechanisms, leading to delayed larvae development. The MSF protocol resulted in plasma membrane rupture and lack of fertilisation success post-thawing. Our results provide the first report on the molecular basis underlying the limited success in cryopreserving mussel oocytes, showing EG as less harmful compared to DMSO, and supports supplementing cryoprotectants with external antioxidants and membrane stabilisers to improve cryopreservation of marine invertebrate oocytes.