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NBRP Fundamental Technologies Upgrading Program Project's Progress

Medaka

Focus Production of functional gametes derived from cryopreserved germ-line stem cells using a surrogate broodstock system in medaka
Principal Investigator Goro Yoshizaki   Graduate School of Marine Science and Technology, Tokyo University of Marine Science and Technology
Project Period FY2012–2013
Overview   Although numerous inbred lines and endangered wild populations of medaka currently exist, the only method currently available for preserving medaka genetic resources is to rear live individuals, as protocols for cryopreserving fish eggs or embryos have not yet been successfully established. However, rearing live individuals is always associated with the risk of mutation due to mobile elements, and the loss of parental fish through infectious disease or accidents related to rearing conditions and equipment. To overcome these obstacles, as in a previous experiment using trout, we will attempt to cryopreserve germ-line stem cells, which we will then transplant into recipient medaka. The proposed study will therefore involve the following steps: 1) develop a method to vitrify whole medaka testes, 2) optimize techniques for transplanting germ-line stem cells into the body cavity of newly hatched larvae, which have poorly developed immune systems. After transplantation, the donor-derived germline stem cells are expected to migrate towards the gonads of the recipients where they will undergo gametogenesis. Finally, we intend to establish a method for mass producing sterile triploid medaka which can then be used as recipients to obtain surrogates that produce only donor-derived sperm and eggs. These techniques will facilitate the establishment of a stable and reliable system for preserving valuable medaka strains semi-permanently.
Project's Progress