Ultraviolet radiation and multiple stressor effects on zebrafish embryos
Pelagic embryos of fish may be exposed to high doses of natural UV radiation. Shortwave UV, UVB, as well as UVA may penetrate the water column to depths of several metres. The penetration depth differs depending on the contents of particles, dissolved matter or pollutants. Pollutants may also interact photochemically with UV and visible radiation.
The aim of this study was to establish the dose-effect relationship of phenotypic changes caused by UV in order to plan further multistressor studies including ionising radiation. A modification of the antioxidant defence was studied by adding a methacrylate that was previously found to decrease the amount of glutathione in cells [1].
The zebrafish embryo test [2] was applied to score toxic effects of UVA and UVB. Embryos were treated in the period including mid to late blastula stage, i.e. until 5 hours post fertilisation. Radiation exposure was performed with a modified polymerisation unit equipped with various broadband fluorescent units with UVC filter.
The broadband UVB source was approximately 1000 times more effective in inducing morphological lesions and embryo death of the exposed embryos than was the UVA source. Comparison with published action spectra indicates that DNA damage may be a major factor in the pathway leading to the observed effects.
Hydroxyethyl methacrylate increased the UVB-induced effects on the embryos significantly. This finding indicates that synergistic effects may be induced if UV radiation and chemical pollutants interact in the environment.
References:
[1] T Christensen, E Bruzell, Photochem. Photobiol. Sci., 2010, 9, 1597.
[2] OECD Test Guideline (TG) 236, Fish Embryo Acute Toxicity (FET) Test, 26 July 2013.
Authors:
Terje Christensenad, Thomas B. Aleksandersenad, Peter Aleströmbd, Jan L. Lychebd and Ellen M. Bruzellc.
