Survey for Karlotoxin Production in 15 Species of Gymnodinioid Dinoflagellates (Kareniaceae, Dinophyta)1

Toxin analysis of 15 species of Kareniaceae revealed the presence of karlotoxin, KmTx 2, in only a single species (Karlodinium veneficum) but with variable activity in strains from the Swan (Km(Swan) Tx 2-1, 2.1 pg · cell(-1) ; and Km(Swan) Tx 2-2, 0.53 pg · cell(-1) ), Huon (Km(Huon) Tx 2, 0.86 pg · cell(-1) ), and Derwent rivers (<0.001 pg · cell(-1) ) in Australia. A newly isolated Southern Ocean species, Karlodinium conicum, contained a novel poorly hemolytic karlotoxin analogue (Kmconicum Tx, 2.8 pg · cell(-1) ). The hemolytic potency (HD50%) of the Australian karlotoxins were as follows: Km(Swan) Tx 2-1 (65.9 ± 4.8 ng) and Km(Swan) Tx 2-2 (63.4 ± 3.7 ng), Km(Huon) Tx 2 (343 ± 4.9 ng), and Kmconicum Tx (>4,000 ng). Species from the closely related genera Takayama (T. helix, T. tasmanica, T. tuberculata), Karenia (K. asterichroma, K. brevis, K. mikimotoi, K. papilionacea, K. umbella), and Karlodinium (Ka. australe, Ka. antarcticum, Ka. ballantinum, Ka. corrugatum, Ka. decipiens) were all consistently negative for karlotoxin production. Brevetoxin (PbTx) was only detected in K. brevis, and hemolytic activity was only observed in Ka. veneficum strains.