title: UV-B-induced synthesis of mycosporine-like amino acids in three strains of Nodularia (cyanobacteria).
abstract: Three filamentous and heterocystous cyanobacterial strains of Nodularia, Nodularia baltica, Nodularia harveyana and Nodularia spumigena, have been tested for the presence and induction of ultraviolet-absorbing/screening mycosporine-like amino acids (MAAs) by simulated solar radiation in combination with 395 (receiving photosynthetically active radiation (PAR) only), 320 (receiving PAR + UV-A) and 295 (receiving PAR + UV-A + UV-B) nm cut-off filters. Absorption spectroscopic analyses of the methanolic extracts of samples revealed a typical MAA peak at 334 nm in all three cyanobacteria. Specific contents of MAAs had a pronounced induction in the samples covered with 295 nm cut-off filters after 72 h of irradiation. In comparison, there was little induction of MAAs in the samples covered by 395 and 320 nm cut-off filters. High performance liquid chromatographic (HPLC) studies revealed the presence of two types of MAAs in all three cyanobacteria, which were identified as shinorine and porphyra-334, both absorbing maximally at 334 nm. The occurrence of porphyra-334 is rare in cyanobacteria. Specific content of both shinorine and porphyra-334 were induced remarkably only in the samples covered with 295 nm cut-off filters. The results indicate that in comparison to UV-A and PAR, UV-B is more effective in eliciting MAAs induction in the studied cyanobacteria.
authors.affiliation: Institut für Botanik und Pharmazeutische Biologie, Friedrich-Alexander-Universität, Staudtstr. 5, Erlangen D-91058, Germany.
authors.forename: Rajeshwar P
authors.initials: RP
authors.lastname: Sinha
authors.forename: Navin K
authors.initials: NK
authors.lastname: Ambasht
authors.forename: Jiweshwar P
authors.initials: JP
authors.lastname: Sinha
authors.forename: Manfred
authors.initials: M
authors.lastname: Klisch
authors.forename: Donat P
authors.initials: DP
authors.lastname: Häder
mesh_terms: D000596:Amino Acids / Q000138:chemical synthesis* / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D000458:Cyanobacteria / Q000737:chemistry / Q000528:radiation effects*; D013045:Species Specificity; D014466:Ultraviolet Rays
chemical_list: D000596:Amino Acids