title: Osmotic stress does not trigger brevetoxin production in the dinoflagellate Karenia brevis.
abstract: With the global proliferation of toxic harmful algal bloom species, there is a need to identify the environmental and biological factors that regulate toxin production. One such species, Karenia brevis, forms nearly annual blooms that threaten coastal regions throughout the Gulf of Mexico. This dinoflagellate produces brevetoxins, which are potent neurotoxins that cause neurotoxic shellfish poisoning and respiratory illness in humans, as well as massive fish kills. A recent publication reported that a rapid decrease in salinity increased cellular toxin quotas in K. brevis and hypothesized that brevetoxins serve a role in osmoregulation. This finding implied that salinity shifts could significantly alter the toxic effects of blooms. We repeated the original experiments separately in three different laboratories and found no evidence for increased brevetoxin production in response to low-salinity stress in any of the eight K. brevis strains we tested, including three used in the original study. Thus, we find no support for an osmoregulatory function of brevetoxins. The original publication also stated that there was no known cellular function for brevetoxins. However, there is increasing evidence that brevetoxins promote survival of the dinoflagellates by deterring grazing by zooplankton. Whether they have other as-yet-unidentified cellular functions is currently unknown.
authors.affiliation: Beaufort Laboratory, National Centers for Coastal Ocean Science, National Ocean Service, National Oceanic and Atmospheric Administration, Beaufort, NC 28516, USA.
authors.forename: William G
authors.initials: WG
authors.lastname: Sunda
authors.forename: Cheska
authors.initials: C
authors.lastname: Burleson
authors.forename: D Ransom
authors.initials: DR
authors.lastname: Hardison
authors.forename: Jeanine S
authors.initials: JS
authors.lastname: Morey
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Wang
authors.forename: Jennifer
authors.initials: J
authors.lastname: Wolny
authors.forename: Alina A
authors.initials: AA
authors.lastname: Corcoran
authors.forename: Leanne J
authors.initials: LJ
authors.lastname: Flewelling
authors.forename: Frances M
authors.initials: FM
authors.lastname: Van Dolah
mesh_terms: D004141:Dinoflagellida / Q000378:metabolism* / Q000502:physiology; D005068:Eutrophication / Q000502:physiology*; D060851:Gulf of America; D057097:Harmful Algal Bloom / Q000502:physiology*; D008387:Marine Toxins / Q000096:biosynthesis / Q000378:metabolism*; D009997:Osmotic Pressure / Q000502:physiology*; D035964:Oxocins / Q000378:metabolism*; D054712:Salinity; D012623:Seawater; D014882:Water-Electrolyte Balance / Q000502:physiology; D000095702:Polyether Toxins
chemical_list: D008387:Marine Toxins; D035964:Oxocins; C053342:brevetoxin; D000095702:Polyether Toxins
keywords: HABs; red tides; toxic blooms