Surrogate production of Salmo salar oocytes and sperm in triploid Oncorhynchus mykiss by germ cell transplantation technology

Surrogate broodstock technology is emerging as a promising biotechnology for xenogeneic production of gametes of highly valuable fish species. In this study, we produced gametes of landlocked Atlantic salmon using triploid rainbow trout as recipient through germ cell transplantation technique in embryos. Spermatogonial cells were obtained from Atlantic salmon juveniles and transplantation conducted into the coelomic cavity of 150 mixed-sex triploid embryos of rainbow trout. Colonization efficiency assessed in larvae four weeks post-transplantation showed presence of PKH-26-labeled cells in 61.1% of individuals. Analysis in sexually mature adults revealed presence of donor-derived sperm in four transplanted males (10%), whereby one of them reached sexual maturity in the first year. Transplanted females became mature after the second year and donor-derived oocytes were detected in four individuals (12.1%). Milt produced by transplanted triploid males were used for artificial insemination. Genetic analysis of hatchlings revealed that progeny was composed by pure Atlantic salmon and therefore were donor-derived. In conclusion, this study shows that surrogate broodstock can be used to produce oocytes and spermatozoa using species from different genus. The production of surrogate gametes using species with a shorter life cycle represents an efficient approach to streamline the development of improved strains in aquaculture industry.