UV-induced DNA damage in Cyclops abyssorum tatricus populations from clear and turbid alpine lakes

Abstract

Zooplankton from clear alpine lakes thrive under high levels of solar UV radiation (UVR), but in glacially turbid ones they are more protected from this damaging radiation. Here, we present results from experiments done with Cyclops abyssorum tatricus to assess UV-induced DNA damage and repair processes using the comet assay. Copepods were collected from three alpine lakes of differing UV transparency ranging from clear to glacially turbid, and exposed to artificial UVR. In addition, photoprotection levels [mycosporine-like amino acids (MAAs) and lipophilic antioxidant capacity] were estimated in the test populations. Similar UV-induced DNA damage levels were observed among the copepods from all lakes, but background DNA damage (time zero and dark controls) was lowest in the copepods from the glacially turbid lake, resulting in a higher relative DNA damage accumulation. Most DNA strand breaks were repaired after recovery in the dark. Low MAA concentrations were found in the copepods from the glacially turbid lake, while the highest levels were observed in the population from the most UV transparent lake. However, the highest lipophilic antioxidant capacities were measured in the copepods from the lake with intermediate UV transparency. Photoprotection and the ability to repair DNA damage, and consequently reducing UV-induced damage, are part of the response mechanisms in zooplankton to changes in water transparency caused by glacier retreat.

The Impact of UV Radiation on Paramecium Populations from Alpine Lakes

“…The extent of the DNA damage in the ciliates after UVR + PAR exposure was similar to the DNA damage levels reported for UV‐exposed copepods from clear and turbid alpine lakes (Tartarotti et al. ). The background damage at t 0 was significantly higher ( P < 0.05) at 8 °C and lower in the Paramecium population from the turbid than from the clear lake (not statistically significant; Fig.…”

“…All subsequent steps of the alkaline comet assay and the quantitation of the DNA damage followed a modified protocol of Tartarotti et al. () and references therein. We applied a short lysis time (2 h) with a modified lysis buffer by adding Sarcosyl 0.2% (Sigma‐Aldrich, Vienna, Austria), and a short electrophoresis run (5 min).…”

“…The response to UVR of aquatic organisms originating from alpine lakes of contrasting UVR transparency was recently compared in copepods using a single‐cell gel electrophoresis method (comet assay; Tartarotti et al. ). Higher relative DNA damage accumulation under UVR exposure was observed in the population from the turbid lake.…”

“…Adaptive traits such as photoprotection by sunscreen compounds and DNA repair mechanisms are seen to be a prerequisite for these organisms to thrive in clear lakes (Tartarotti et al. ).…”

Water Browning Influences the Behavioral Effects of Ultraviolet Radiation on Zooplankton

“…Especially for zooplankton residing in browning waters, the net result of increased DOM levels is thus seen as primarily positive. This is largely due to photoprotection from UVR, which is known to be harmful via a range of mechanisms, including direct DNA damage, protein denaturation and lipid peroxidation (Pellegri et al, 2014;Tartarotti et al, 2014). Interactions between DOM and UVR have been shown to affect growth and survival of zooplankton, as well as inducing DNA damages (Rautio and Korhola, 2002;Geddes, 2009;Wolf et al, 2017).…”