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Authordc.contributor.authorSoto Liebe, Katia 
Authordc.contributor.authorMéndez A., Marco es_CL
Authordc.contributor.authorFuenzalida, Loreto es_CL
Authordc.contributor.authorKrock, Bernard es_CL
Authordc.contributor.authorCembella, Allan es_CL
Authordc.contributor.authorVásquez, Mónica es_CL
Admission datedc.date.accessioned2014-01-08T15:15:30Z
Available datedc.date.available2014-01-08T15:15:30Z
Publication datedc.date.issued2012
Cita de ítemdc.identifier.citationToxicon 60 (2012) 1324–1334en_US
Identifierdc.identifier.otherDOI:10.1016/j.toxicon.2012.09.001
Identifierdc.identifier.urihttps://repositorio.uchile.cl/handle/2250/119662
General notedc.descriptionArtículo de publicación ISIen_US
Abstractdc.description.abstractParalytic shellfish poisoning (PSP) toxins are a group of naturally occurring neurotoxic alkaloids produced among several genera of primarily freshwater cyanobacteria and marine dinoflagellates. Although saxitoxin (STX) and analogs are all potent Naþ channel blockers in vertebrate cells, the functional role of these compounds for the toxigenic microorganisms is unknown. Based upon the known importance of monovalent cations (such as sodium) in the maintenance of cellular homeostasis and ion channel function, we examined the effect of high extracellular concentrations of these ions on growth, cellular integrity, toxin production and release to the external medium in the filamentous freshwater cyanobacterium, Raphidiopsis brookii D9; a gonyautoxins (GTX2/3) and STX producing toxigenic strain. We observed a toxin export in response to high (17 mM) NaCl and KCl concentrations in the growth medium that was not primarily related to osmotic stress effects, compared to the osmolyte mannitol. Addition of exogenous PSP toxins with the same compositional profile as the one produced by R. brookii D9 was able to partially mitigate this effect of high Naþ (17 mM). The PSP toxin biosynthetic gene cluster (sxt) in D9 has two genes (sxtF and sxtM) that encode for a MATE (multidrug and toxic compound extrusion) transporter. This protein family, represented by NorM in the bacterium Vibrio parahaemolyticus, confers resistance to multiple cationic toxic agents through Naþ/drug antiporters. Conserved domains for Naþ and drug recognition have been described in NorM. For the D9 sxt cluster, the Naþ recognition domain is conserved in both SxtF and SxtM, but the drug recognition domain differs between them. These results suggest that PSP toxins are exported directly in response to the presence of monovalent cations (Naþ, Kþ) at least at elevated concentrations. Thus, the presence of both genes in the sxt cluster from strain D9 can be explained as a selective recognition mechanism by the SxtF/M transporters for GTX2/3 and STX. We propose that these toxins in cyanobacteria could act extracellularly as a protective mechanism to ensure homeostasis against extreme salt variation in the environment.en_US
Lenguagedc.language.isoen_USen_US
Type of licensedc.rightsAttribution-NonCommercial-NoDerivs 3.0 Chile*
Link to Licensedc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/3.0/cl/*
Keywordsdc.subjectCyanobacteriaen_US
Títulodc.titlePSP toxin release from the cyanobacterium Raphidiopsis brookii D9 (Nostocales) can be induced by sodium and potassium ionsen_US
Document typedc.typeArtículo de revista


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Except where otherwise noted, this item's license is described as Attribution-NonCommercial-NoDerivs 3.0 Chile