Production of chimeric rainbow trout and blastomere cryopreservation: A framework for preserving and re-establishing into a breeding population the germ plasm of fish

Conserving the genetics of rare or endangered fish strains is of growing concern to the scientific and public communities. New techniques are needed to preserve and manipulate the germ plasm of selected fish species to retain genetic diversity in the populations and to overcome one limitation of sperm cryopreservation. Sperm cryopreservation does not preserve mitochondrial DNA, which is maternally inherited. The objective of these investigations was to develop a set of procedures which would provide the framework for preserving and re-establishing into a breeding population the germ plasm of rainbow trout, including the mitochondrial DNA. This objective will be met by transplanting isolated blastomeres into recipient blastulae with the resultant formation of chimeric rainbow trout (Oncorhynchus mykiss), by investigating the cellular composition of these chimeras and by cryopreserving isolated embryonic cells.; The objective of the first investigation was to produce chimeric rainbow trout. The results demonstrated that chimeric rainbow trout embryos were produced, supporting the hypothesis that blastomeres isolated from rainbow trout embryos could be incorporated and continue to develop when injected into the subgerminal cavity of recipient embryos. The objective of the second investigation was to determine if the donor and recipient cells used to produce chimeric rainbow trout were randomly distributed in these chimeric animals. The results of this investigation support the hypothesis that the donor cells are no more likely to colonize one tissue or organ type than another. The objective of the third investigation was to determine if rate of cooling or sample container shape affects the proportion of rainbow trout blastomeres which survive cryopreservation. Results from this study support the hypothesis that isolated blastomeres of rainbow trout can be successfully cryopreserved and thawed, and that sample container shape affects cryopreservation success.