Relative sensitivity of DNA and photosystem II in Ulva intestinalis (Chlorophyta) under natural solar irradiation

Marine Ecology Progress Series

Lars Nichelmann¹  Frauke Pescheck¹  Hanna Campen¹  Wolfgang Bilger¹ 

关键词: Diel cycle;    DNA damage;    Intertidal zone;    Long-term data;    Photosynthetic efficiency;    Ultraviolet radiation;    Sunlight;    Ulva intestinalis;   

DOI  :  10.3354/meps11802

学科分类：海洋学与技术

来源: Inter-Research

【 摘 要 】

ABSTRACT: High intensities of sunlight can result in DNA and photosystem II (PSII) damage. However, the relative sensitivity of both these targets under natural sunlight and especially over a long period has not been studied in algae so far. Although DNA damage is highly specifically induced by ultraviolet-B radiation (UVB, 280-315 nm), PSII is inactivated by a broad spectrum. The green macroalga Ulva intestinalis is an appropriate and interesting study organism with which to investigate the relative importance of the 2 different targets of sunlight because this alga contains no UV-screening protective pigments, although it is exposed to strong solar irradiation in its natural habitat. This entails a high risk of DNA damage. Therefore, diel time courses and long‑term development of DNA damage and the optimal quantum yield of PSII (F_v/F_m) were studied in situ. F_v/F_m was extremely reduced at noon, but a fast recovery was observed in the afternoon. As dark-adapted basal fluorescence (F_o) of PSII was substantially decreased during the day, non-photochemical quenching is suggested to be a key photoprotective strategy in U. intestinalis. In contrast, even in samples with strongly reduced F_v/F_m, only very low DNA damage was found, irrespective of the accumulated UVB dose. We propose that efficient photoreactivation driven by natural sunlight balances the induction of dimers. This leads to a higher UVB tolerance of DNA than that observed in algae under experimental UVB irradition. In this field study, U. intestinalis suffered more from photoinhibition than from DNA damage.

【 授权许可】

Unknown