Thermal compensation reduces DNA damage from UV radiation

Area of Science:

• Environmental toxicology
• Amphibian ecophysiology
• DNA damage and repair

Background:

• Global amphibian declines correlate with increased ultraviolet radiation (UVR) and other stressors.
• UV radiation is a mutagen that damages DNA, with higher damage observed in amphibian larvae at cool temperatures.
• The capacity of amphibians to acclimate to UVR and temperature interactions on DNA damage is not well understood.

Purpose of the Study:

• To investigate the capacity of striped marsh frog larvae (Limnodynastes peronii) to acclimate to UVR and temperature, specifically their effect on DNA damage.
• To determine if thermal acclimation can compensate for UVR-induced DNA damage in amphibian larvae.

Main Methods:

• Larvae were reared at warm (25°C) and cool (15°C) temperatures under low or moderate UVR doses for 18-20 days.
• Following acclimation, larvae were exposed to a high UVR dose at various temperatures (10-30°C) to measure DNA damage.
• DNA damage levels were quantified to assess the effects of temperature acclimation and UVR exposure.

Main Results:

• Larvae acclimated to cool temperatures (15°C) and exposed to UVR at 15°C showed complete compensation of UVR-induced DNA damage.
• Warm-acclimated larvae (25°C) exhibited higher DNA damage than cold-acclimated larvae across all test temperatures.
• No evidence of UVR acclimation was found in larvae reared under elevated UVR levels, as indicated by DNA damage levels after high UVR exposure.

Conclusions:

• Thermal acclimation in Limnodynastes peronii larvae can compensate for UVR-induced DNA damage, particularly at cooler temperatures.
• Aquatic ectotherms inhabiting cooler environments may possess greater resilience to high UVR than previously assumed.
• Amphibian species with limited capacity for thermal acclimation of DNA repair may face increased risks from combined changes in temperature and UVR regimes.