Interspecific germ cell transplantation: a new light in the conservation of valuable Balkan trout genetic resources?
Interspecific transplantation of germ cells from the brown trout Salmo trutta m. fario and the European grayling Thymallus thymallus into rainbow trout Oncorhynchus mykiss recipients was carried out in order to improve current practices in conservation of genetic resources of endangered salmonid species in the Balkan Peninsula. Current conservation methods mainly include in situ efforts such as the maintenance of purebred individuals in isolated streams and restocking with purebred fingerlings; however, additional ex situ strategies such as surrogate production are needed. Steps required for transplantation such as isolation of high number of viable germ cells and fluorescent labeling of germ cells which are to be transplanted have been optimized. Isolated and labeled brown trout and grayling germ cells were intraperitoneally transplanted into 3 to 5 days post hatch rainbow trout larvae. Survival of the injected larvae was comparable to the controls. Sixty days after transplantation, fluorescently labeled donor cells were detected within the recipient gonads indicating successful incorporation of germ cells (brown trout spermatogonia and oogonia—27%; grayling spermatogonia—28%; grayling oogonia—23%). PCR amplification of donor mtDNA CR fragments within the recipient gonads additionally corroborated the success of incorporation. Overall, the transplantation method demonstrated in this study presents the first step and a possible onset of the application of the germ cell transplantation technology in conservation and revitalization of genetic resources of endangered and endemic species or populations of salmonid fish and thus give rise to new or improved management strategies for such species.
KeywordsSpermatogonia Oogonia Transplantation Salmo trutta Thymallus thymallus
We would like to thank Dr. Goro Yoshizaki and his team for the valuable training and support during this research. We would also like to express our gratitude to the manager of the Bled hatchery (Slovenia) for providing juvenile fish for all the experiments and the manager of the Vodomec hatchery (Slovenia) for rearing the rainbow trout fry.
This study was supported by the National Research, Development and Innovation Office of Hungary (grants SNN 116912 to ÁH and FK 124585 to JL), the Slovenian Research Agency (grants N4-0045 and P4-0220), and the Stipendium Hungaricum Scholarship Programme (grant 106360 to ZM).
Compliance with ethical standards
Treatment of the animals was carried out following the Slovenian national regulations, and the experimental procedures were approved by the Administration of the Republic of Slovenia for Food Safety, Veterinary Sector and Plant Protection, Ministry of Agriculture and Environment (decision letter U34401-30/2013/4).
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