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The uses of cryopreserved cells

Cell cryopreservation and cryobanking in aquatic species is a unique tool to preserve the genome of domesticated species over the many steps of selective breeding, the later being increasingly developed since the 1990ies, to diffuse the genetic progress, and to facilitate broodstock management by extending or delaying offspring production. To some extent, it can also provide a back-up tool in the case of endangered species.

New species, new cell types candidate for cryopreservation

In the past, most of our research was dedicated to sperm cryopreservation. Today, only few species have spermatozoa that cannot be successfully cryopreserved. In fish, oocytes and whole embryos cannot be cryopreserved because of the fragility of the yolk sac. This is why we set up the cryopreservation of fin cells and tissues which allow the preservation of both parental genome whatever the age or sex of the donor. In the same line, we are optimizing the cryopreservation of germinal stem cells, whose grafting into the gonad of a recipient fry allows the production of both spermatozoa and ova bearing the donor genome. Last, we set up a new method for oyster larvae cryopreservation.

Epigenetic risk assessment after cryopreservation

In fish, most of the most efficient cryoprotectants bear reactive methyl groups (methanol, dimethyl sulfoxide, dimethyl formamide) known to provide methyl groups to DNA in oxidative conditions. We are developing an important project to determine the stability of the DNA methylation profile after cryopreservation in several farmed species. We are also characterizing whether some specific regions in sperm chromatin are more fragile towards cryopreservation, in order to assess the risk to transmit alterations to the next generation. Indeed, it is now well recognized that the DNA methylation profile in sperm plays a role in the proper establishment of gene expression after the embryonic genome activation and during development.