Geographic differences in paralytic shellfish poisoning toxin profiles among Japanese populations of Alexandrium tamarense and A. catenella (Dinophyceae)

Abstract

SUMMARY To reconsider whether toxin profile could be used as a marker for populations from different geographical areas, clonal isolates of the toxic dinoflagellates Alexandrium tamarense (Lebour) Balech and Alexandrium catenella (Whedon et Kofoid) Balech from Ofunato Bay (Iwate Prefecture), Atsumi Bay (Aichi Prefecture), Tanabe Bay (Wakayama Prefecture), Harima-Nada (Kagawa Prefecture), Uranouchi Bay (Kochi Prefecture), Hiroshima Bay (Hiroshima Prefecture) and Yamakawa Bay (Kagoshima Prefecture), which were identified on the basis of morphotaxonomy, immunological and molecular biological techniques, were subjected to analysis of paralytic shellfish poisoning toxins by high performance liquid chromatography-fluorometric method. All the isolates except A. tamarense OF152 from Ofunato Bay contained mainly N-sulfocarbamoyl toxins (C1 +2) with various amounts of derivatives, and a typical north-to-south trend of decreasing toxicity was observed. In both A. tamarense and A. catenella, toxin profiles were rather constant within a geographical area and divergent among different geographical areas. The toxin profiles of A. tamarense from Harima-Nada were well conserved among different bloom years. Toxin profile showed that isolates of A. tamarense from Ofunato Bay, A. tamarense from Harima-Nada isolated in 1988 and A. catenella from Uranouchi Bay were heterogeneous. However, only two or three groups of isolates with different toxin profiles were observed in a geographical region, suggesting that several representative isolates express the genotype in a given region. These observations confirmed that toxin composition could be used as a marker to discriminate different geographical populations of these species.