Using dinoflagellate cox1 primer sets dinocox1F5-R3 [24] and universal cox1 primer set cox1_5b-3a (Table 2) , DNA fragments were amplified from genomic and cDNA templates of P. marinus (0.96 kb) and cDNA of P. chesapeaki (0.33 kb), respectively. Direct sequencing of these fragments proved that they were cox1 sequences with 50-60% identity to that of dinoflagellates and apicomplexans. When the 0.96-kb P. marinus cox1 sequence was used to BLAST against the P. marinus genome database, one 3147-bp sequence (AAXJ01004741) was obtained with 100% identity to the P. marinus DNA fragment we found. Nearly full-length cDNAs of cox1 were generated by PCR amplification using Perkinsus-specific cox1 primers for both Perkinsus species (GenBank accession numbers HQ670238, HQ670240; Figure 5 , Table 2 ). Both the cob and cox1 cDNA sequences matched the corresponding genomic DNAs, indicating that no mRNA editing events occurred in either transcript.