Characterization of polar brevetoxin derivatives isolated from Karenia brevis cultures and natural blooms

The toxic effects of three dinoflagellate species from the genusKareniaon invertebrate larvae and finfish

“…The strain of K. brevis used in the present study was from Florida and produced four main BTXs which were each present in the SPE extracts as the parent toxin and the lactone ring-opened hydrolysis product (Abraham et al 2006). The total concentration of these BTXs in the culture at 20 days was 490 mg L Á1 (52 pg cell Á1 ).…”

“…The toxic mechanism of K. brevis in fish is believed to relate to BTXs from cells or water being absorbed directly across the gill membranes of fish. Type A BTXs such as BTX-1 are more potent than Type B BTXs (BTX-2, BTX-3) (Baden 1989;Landsberg 2002;Abraham et al 2006). Lethal concentrations for 50% of fish exposed for 24 h were 3Á4 nM for BTX-1, 16Á25 nM for BTX-2 and 10Á37 nM for BTX-3 (Baden 1989).…”

“…1B). In contrast, K. brevis cultures produced mainly the lactone ring-closed BTXs with only c. 10Á20% of the ring-opened hydrolysis products (Abraham et al 2006). The toxin productivity was also higher for K. brevis (52 pg cell Á1 ) than K. brevisulcata (0.5 pg cell Á1 ).…”

Loss of waterborne brevetoxins from exposure to phytoplankton competitors

“…We found that PbTx-2 and PbTx-3 shared almost identical standard curves within the range of 0-1 mg mL À1 , and therefore we quantified PbTx-3 concentrations for Experiments 4 and 5 by comparison to a PbTx-2 standard curve. We also checked for PbTx-9 ions ([M+H] + m/z 899), known shellfish metabolite ions (Morohashi et al, 1995;Poli et al, 2000), and oxidation product ions (Abraham et al, 2006) to determine if PbTx-2 had been converted into other previously described brevetoxin forms. Intracellular and extracellular extracts collected after 9 d from Experiment 1 were combined for each replicate and further analyzed by a competitive ELISA for total type II brevetoxins as reported by Naar et al (2002).…”

“…When released by cell lysis, brevetoxin molecular structures can be altered abiotically by oxidative and UV-intense conditions found during blooms (Abraham et al, 2006). In addition, some marine organisms have been shown to metabolize brevetoxins (Poli et al, 2000;Naar et al, 2004;Plakas et al, 2004;Wang et al, 2004).…”