Ultraviolet Radiation-Induced Changes in Mycosporine-Like Amino Acids and Physiological Variables in the Red Alga Lemanea fluviatilis

ABSTRACT

Samples of Lemanea fluviatilis were cultured in the laboratory under three different radiation regimes, which included the absence and presence of ultraviolet (UV) radiation. Photosynthetic pigment composition, photosynthetic activity, and mycosporine-like amino acids (MAAs) were analyzed after 16 and 64 h of exposure to the radiation. Two MAAs were identified as porphyra-334 and mycosporine-glycine. Mycosporine-glycine was specifically induced by UV-B radiation, but porphyra-334 was degraded by this radiation. The level of UV irradiance used in the induction experiment produced damages in the alga as revealed by reductions in photosynthetic activity and photosynthetic pigments (chlorophyll, phycocyanin, and total carotenoids). Our results indicate that the MAAs failed to fully protect the photosynthetic machinery against UV-B under the specific conditions used in this study.