The occurrence of UV-B absorbing mycosporine-like amino acids in freshwater and terrestrial microalgae (Chlorophyta)

The occurrence of mycosporine-like amino acids (MAAs) in freshwater and ter restrial microalgae and their accumulation in response to W-B exposure were examined. Three UV-B-resistant species, Enallax coelastroides, Scenedesmus sp. and Scotiella chlorelloidea, and four WE-sensitive microalgal species: Ankistrodesmus spiralis, Chlorella minutissima, Chlorella sorokiniana and Pseudococcomyxa sp, were found to contain MAAs. However, Coelastrum micropo rum did not appear to contain any MAA. A total of seven MAAs was identified among the tested species. Besides five known MAAs: mycosporine-Gly (lambda (max) = 310 nm), palythine (lambda(max) = 320 nm), asterina (lambda(max) = 330 nm), shinorine (lambda(max) = 334 nm) and porphyra (lambda(max) = 334 n m), two novel compounds (compound I: lambda(max) = 302 nm, Rt = 2.6 min; co mpound II: lambda(max) = 292 nm, Rt = 7.3 min) were found in Ch. sorokinian a and Scenedesmus sp. The accumulation of MAAs was induced by both artifici al and solar UV-B radiation, which was observed in both the W-B-resistant a nd W-B-sensitive species, No clear correlation between MAA accumulation and UV-B resistance of the photosynthetic apparatus was established. The respo nse of MAA accumulation to W-B exposure was species-dependent and individua l MAA-specific. (C) 1999 Elsevier Science B.V. All rights reserved.