Partial sequence of the 24S rRNA and polymerase chain reaction based assay for the toxic dinoflagellate Dinophysis acuminata

We describe the polymerase chain reaction (PCR) amplification of an 805 base pair fragment of 24S rRNA from the toxic dinoflagellate Dinophysis acuminata and the sequence of this fragment. We also describe a PCR-based assay for the specific detection of D. acuminata in seawater samples. Conserved primers, starting at positions 711 and 1489 of the 24S rRNA from the dinoflagellate Prorocentrum micans, were used for the PCR. The PCR product was cloned and sequenced. The fragment was aligned with rRNA sequences from other protists. Two oligonucleotides in variable domains of the sequence from D. acuminata were chosen and a protocol was defined for PCR-based detection of D. acuminata (30 cycles, 50 degrees C). Experiments conducted with seawater samples led to the detection of D. acuminata in naturally contaminated samples. The PCR enabled us to detect down to 30 cells/L seawater. The problem of interference from large concentrations of other phytoplankton species may be solved using nested PCR.