Cold-induced skin darkening does not protect amphibian larvae from UV-associated DNA damage

Abstract

O_LIMany amphibian declines are correlated with increasing levels of ultraviolet radiation (UVR). While disease is often implicated in declines, environmental factors such as temperature and UVR play an important role in disease epidemiology. C_LIO_LIThe mutagenic effects of UVR exposure on amphibians are worse at low temperatures. Amphibians from cold environments may be more susceptible to increasing UVR. However, larvae of some species demonstrate cold acclimation, reducing UV-induced DNA damage at low temperatures. Understanding of the mechanisms underpinning this response is lacking. C_LIO_LIWe reared Limnodynastes peronii larvae in cool (15{degrees}C) or warm (25{degrees}C) waters before acutely exposing them to 1.5 h of high intensity (80 W cm-2) UVBR. We measured the colour of larvae and mRNA levels of a DNA repair enzyme. We reared larvae at 25{degrees}C in black or white containers to elicit a skin colour response, and then measured DNA damage levels in the skin and remaining carcass following UVBR exposure. C_LIO_LICold acclimated larvae were darker and displayed lower levels of DNA damage than warm-acclimated larvae. There was no difference in CPD-photolyase mRNA levels between cold- and warm-acclimated larvae. Skin darkening in larvae did not reduce larval accumulation of DNA damage following UVR exposure. C_LIO_LIOur results showed that skin darkening alone does not explain cold-induced reductions in UV-associated DNA damage in L. peronii larvae. Beneficial cold-acclimation is more likely underpinned by increased CPD-photolyase abundance and/or increased photolyase activity at low temperatures. C_LI Research HighlightsO_LIL. peroniii larvae darken when exposed to cold temperatures C_LIO_LIDarker larvae were not protected from the effects of UV on DNA damage C_LIO_LICold acclimation of larvae when exposed to UV is likely driven by DNA repair enzymes not melanin C_LI