Production of germ cell-deficient salmonids by dead end gene knockdown, and their use as recipients for germ cell transplantation.

We previously established a spermatogonial transplantation model in fish using triploid recipients. Although triploid salmonids are sterile, they carry a limited number of immature triploid germ cells that potentially compete with the donor-derived germ cells for their niche. We therefore assessed the biological characteristics of germ cell-deficient gonads in rainbow trout for their suitability as recipients for germ cell transplantation in this study.

Spermatogonial transplantation in fish: A novel method for the preservation of genetic resources.

Recent progress in genome-based breeding has created various fish strains carrying desirable genetic traits; however, methods for the long-term preservation of their genetic resources have not yet been developed, mainly due to the lack of cryopreservation techniques for fish eggs and embryos. Recently, we established an alternative cryopreservation technique for fish spermatogonia using a slow-freezing method. Furthermore, we developed a transplantation system to produce functional eggs and sperm derived from spermatogonia.