Preliminary result of de novo transcriptome sequencing of the marine toxic dinoflagellate Alexandrium catenella incubated under several different stresses

In cold water coastal regions, the marine dinoflagellate Alexandrium catenella (Group I) is associated with paralytic shellfish poisoning. Here, we characterized the transcriptome of A. catenella isolated from Korean coastal waters during spring. RNA sequencing generated 15.5 Gb nucleotides that were assembled into 103,362 unique transcripts (unigenes). Upon comparison with known proteins, 53,547 (51.81%) unigenes were successfully annotated in public databases, among which, 28,463 and 35,447 unigenes were assigned to gene ontology categories and evolutionary genealogy of genes with enhanced non-supervised orthologous groups, respectively. Notably, we identified numerous toxin- and cold response-related genes in this species. The conserved dinoflagellate spliced leader (dinoSL) was detected in many unigenes, thereby indicating the occurrence of trans-splicing mRNA processing. Moreover, the identification of second or third dinoSL relicts in a few genes indicate that they have been recycled in the past between the genome and mRNA and are potential sources of genome expansion in this species.