Transcriptomic approach to identify toxin producing genes in the dinoflagellate Alexandrium tamutum. Alexandrium tamutum

Alexandrium is one of the most common marine microalgal genera responsible for seasonal harmful algal blooms (HAB). Alexandrium sp. are small, marine cyst forming dinoflagellates, which consist of 33 species known up to date. Interestingly, 15 of these have shown to express toxicity. The main toxins produced by the genera are saxitoxin, neosaxitoxin, gonyautoxin, spirolides, goniodomines and tetrodotoxin, which harms both marine organisms and humans.Alexandrium tamutum was firstly identified in the Gulf of Naples. It was also chemically analysed, and any known toxins were detected. Considering that A. tamutum showed toxic effects on its predators and anticancer activity, we supposed that it may produce some toxic compounds. The aim of this study was to analyse the transcriptome of A. tamutum in order to identify transcripts coding enzymes involved in toxin production or in synthesis of other possible bioactive compounds. Therefore, suggesting evidence of the toxin production by A. tamutum.Results showed the presence of 2 homologous genes involved in saxitoxin biosynthesis in cyanobacteria, sxtA and sxtU, and 8 other transcripts, annotated for proteins related to toxin biosynthesis: 2 sequences of “toxicos en levadura”, 3 sequences of toxin biosynthesis protein, gliotoxin biosyn-thesis protein and 2 sequences of aflatoxin b1 aldehyde reductase member 4-like and member 2 proteins. The presence of these transcripts, combined with the antipredator and anticancer activities previously observed, suggest the production of toxic compounds. Further chemical analyses will clarify which compounds are produced.