Centrodinium punctatum (Dinophyceae) produces significant levels of saxitoxin and related analogs

Abstract

Centrodinium punctatum is a fusiform dinoflagellate with a global marine distribution. Due to its close relation with Alexandrium species, toxin production was assessed through analysis of culture of one strain from the East China Sea using liquid chromatography coupled to tandem mass spectrometry. The paralytic shellfish toxin (PST) in the strain of C. punctatum was dominated by six analogs, i.e. STX (30%), GTX-1 (20%) and neoSTX (24%), followed by GTX2 (9%), GTX-4 (9%) and GTX3 (8%); deoxy-STX was also putatively identified while no gymnodimines, spirolides or goniodomins were detected. This is the first record of C. punctatum producing saxitoxins. The estimated cellular toxicity was rather elevated, between 91 and 212 pg cell-1 (or 259 and 601 fmol cell-1). When considering the toxicity equivalent factors, results suggest that this species can produce high cellular toxicity compared to other STX-producing dinoflagellates. In addition, morphological details of the sulcal area and the hypotheca of this species were re-examined by scanning electron microscopy (SEM). SEM revealed that in the sulcal area, the left posterior sulcal plate (Ssp) is larger and longer than the left posterior sulcal plate and extended into the hypotheca. A revised interpretation of the sulcus and hypotheca is proposed.