Ultraviolet light-induced impairment of goldfish embryo development and evidence for photo-repair mechanisms

Goldfish Carassius auratus embryos were subjected to artificial ultraviolet-B (UVB) radiation (280-320 nm) at various times during development to evaluate the effects on production of anatomically normal larvae. The UVB radiation used in these experiments included a higher proportion of shorter wavelengths compared to the natural spectrum. The development of embryos exposed to UVB for 2 or 4 h at 26 h post-fertilization was severely impaired whereas similar exposures at 50 or 74 h post-fertilization had no effect. A 2 h exposure to UVB commencing at 2 h post-fertilization did not adversely affect embryonic development whereas a 4 h exposure to a lower dose did. At 50 h post-fertilization, when embryos were normally resistant to UVB, denial of access to visible light and UVA before, during and after exposure to UVB caused impairment of development. Analysis of DNA fragment length after incubation with an endonuclease suggested that UVB damage at 50 h was caused by formation of pyrimidine dimers. This study demonstrated that the sensitivity of goldfish embryos to UVB varied during development and that resistance to UVB in later developmental stages included a photo-repair mechanism.