Ultraviolet radiation dose to be applied in recipient zebrafish embryos for germ-line chimaerism is strain dependent.

Germ-line chimaerism is a powerful technique that has proved to be useful to produce viable gametes when transplanted blastomeres colonize the germinal ridges in recipient embryos and obtaining offspring from such transplanted cells. In fish, ionizing radiations were commonly used for embryo penalization to cancelling the cell participation of recipient embryos in development and in gamete production. The ultraviolet (UV) radiation when compared with other radiation types is cheaper, easier and no special installations are required for its use. So, the aim of this work was to establish the optimal UV radiation dose to be applied in zebrafish embryos at mid-blastula transition stage of development, in order to use them as penalized recipient embryos in futures chimaerism assays. A UV germicide lamp was used as radiation source (0.529 mW/cm(2)). Four exposure levels and three exposure times of UV radiation were tested. The survival rates obtained with the non-dechorionated embryos without lid group suggested that it could be the optimal exposure level to achieve the objective proposed. With the obtained results, we concluded that this UV radiation dose for 60 and 30 s are optimal parameters to penalize recipient wild and gold strain zebrafish embryos, respectively in chimaerism assays, but without involving their survival and apparently normal development.