The synthesis of mycosporine-like amino acids (MAAs) by cultured, symbiotic dinoflagellates

We tested the hypothesis that there is a relation between phylotypes (phylo genetic types, as determined by restriction fragment length polymorphism (R FLP) and partial sequence analysis of the small subunit ribosomal RNA gene (SSUrDNA)) and the synthesis of mycosporine-like amino acids (MAAs) by symb iotic dinoflagellates under the influence of ultraviolet radiation (UV-B/A) and photosynthetically active radiation (PAR). We exposed 27 isolates of s ymbiotic dinoflagellates simultaneously to UV-B/A and PAR, and subsequently determined the MAAs present in cell extracts and in the media. The algae u sed included 24 isolates of Symbiodinium spp. originating from jellyfishes, sea anemones, zoanthids, scleractinians, octocorals, and bivalves, and thr ee others in the genera Gymnodinium, Gloeodinium and Amphidinium from a jel lyfish, an hydrocoral and a flatworm, respectively. In this study, all of t he phylotype A Symbiodinium spp, synthesized up to three identified MAAs. N one of the 11 cultured phylotypes B and C Symbiodinium spp. synthesized MAA s. The three non-Symbiodinium symbionts also synthesized up to three MAAs. The results support a conclusion that phylotype A Symbiodinium spp. have a high predilection for the synthesis of MAAs, while phylotypes B and C do no t. Synthesis of MAAs by symbiotic dinoflagellates in culture does not appea r to relate directly to depths or to the UV exposure regimes from which the consortia were collected. (C) 2000 Elsevier Science B.V. All rights reserv ed.