Monster Seminar JAM -Generation of Viable Fish from Cryopreserved Primordial Germ Cells
Dr. Goro Yoshizaki
Department of Marine Biosciences, Tokyo University of Marine Science and Technology
Fears are growing that many wild salmonid populations are currently facing extinction. Escaped or released farmed fish and exotic species have devastated their native counterparts by hybridizing with wild populations, sometimes driving them to the brink of local genetic extinction. Habitat destruction caused by dam construction and land-management programmes are also threatening rare salmonids, such as the bull trout, California golden trout, and Formosan landlocked salmon.
To maintain the genetic diversity of salmonids, it will be essential to preserve their heritable information. Despite the urgent need to preserve maternal genetic material, fish eggs have not yet been successfully cryopreserved, mainly due to their large size and high yolk content.
Our recently developed novel surrogate broodstock technology allows intraperitoneally introduced primordial germ cells (PGCs) to resume gametogenesis and differentiate into functional spermatozoa in allogenic male recipients. Transplanted PGCs can also differentiate into functional eggs in female recipients. In addition, we successfully xenotransplanted PGCs between rainbow trout and masu salmon. These results suggest that maternally inherited genetic information could be conserved by cryopreserving PGCs. Recently, we also established a cryopreservation method for trout PGCs and confirmed that the cryopreserved PGCs that were transplanted into the peritoneal cavities of allogenic trout hatchlings differentiated into mature spermatozoa and eggs in the recipient gonads. The fertilization of the eggs derived from the donor PGCs by cryopreserved spermatozoa resulted in the development of viable fry. This PGC cryopreservation technique represents a breakthrough in efforts to save threatened fish species.
Date and Time:
October 27, 2005,
11:00 am - 12:30 pm