Ultraviolet Radiation Dose to be Applied in Recipient Zebrafish Embryos for Germ‐line Chimaerism is Strain Dependent

Abstract

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.

Ultraviolet radiation and handling medium osmolarity affect chimaerism success in zebrafish

“…These results could indicate that the osmotic shock produced when chimaerism is performed in 30mOsm/kg micromanipulation medium osmolarity does not apparently affect long term survival in a relevant manner (Cardona-Costa & Francisco-Simão et al ., 2009). As was expected, global survival (cumulative survival) rates in the irradiated groups were significantly lower than in non-irradiated (Francisco-Simão et al ., 2009).…”

“…According to previous results obtained in our laboratory (Francisco-Simão et al ., 2009), gold-type embryos were treated with UV radiation to improve the colonization of transplanted cells during chimaeric embryo development. Briefly, embryo irradiation was carried out almost to mid blastula transition (MBT) stage without dechorionation.…”

“…The use of ultraviolet (UV) radiation is of interest because it is cheaper, easier and less dangerous than other kinds of radiation, and no special installations are required for its use. In our laboratory, a UV radiation dose to penalise recipient embryos was defined specifically for wild and gold zebrafish strains (Francisco-Simão et al ., 2009). On the other hand, in another work, Cardona-Costa & Francisco-Simão et al ., (2009) observed that the micromanipulation medium osmolarity (30 vs 300 mOsm/kg) could affect recipient embryo survival, possibly due to the rupture of the osmolarity barrier when the microinjection pipette punctured the outer embryonic layer.…”

Zebrafish as a possible bioindicator of organic pollutants with effects on reproduction in drinking waters

“…Briefly, adult zebrafish were kept in 20 L tanks at 28.5℃, in a 3:2 ratio (females: males) (Westerfield, 2007) and fed on granular food supplemented with recently defrosted hen egg yolk and shrimp meat (Francisco-Simão et al, 2010). The light cycle was regulated at 14 hr light/10 hr dark (Matthews et al, 2002;Brand et al, 2002).…”

Somatic cells derived from haploid larvae are feasible as donors for nuclear transplant in zebrafish. Preliminary results

“…Irradiation was carried out at 62 cm of focus-object distance, applying a radiation dose of 0.529 mW/cm 2 , measured with a USB 4000 (Miniature Fiber Optic Spectrometer; Ocean Optics Inc. First In Photonics,). A vortex (MS1; IKA-Works Inc.) at 200 rpm was also used with the aim of homogenising the irradiation area during UV exposure (Francisco-Simão et al ., 2010). The sperm irradiation time was 1 min.…”