Document Detail


Feeding mechanics as the basis for differential uptake of the neurotoxin domoic acid by oysters, Crassostrea virginica, and mussels, Mytilus edulis.
MedLine Citation:
PMID:  20153533     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The neurotoxin domoic acid (DA), produced by diatoms Pseudo-nitzschia spp., is transferred to humans via consumption of contaminated bivalves. This study examines feeding mechanisms, namely reduced filtration, pre-ingestive rejection and poor absorption, that might explain the comparatively low DA levels commonly found in oysters during toxic Pseudo-nitzschia blooms. Clearance rate (CR), absorption efficiency (AE) of organic matter and selective rejection in pseudofeces of oysters (Crassostrea virginica) and mussels (Mytilus edulis) were investigated in relation to the DA levels accumulated during 2-wk, simultaneous exposure to toxic Pseudo-nitzschia multiseries. Effects of temperature and P. multiseries cell size were also tested to identify conditions, if any, under which oysters can accumulate unsafe DA levels. Oysters accumulated 3.0-7.5x less DA than mussels from a short-celled P. multiseries clone (length=24microm) at 12 degrees C. This was related to the 7.4-8.5x lower CRs determined for oysters relative to mussels at this temperature. Exposure to a longer-celled P. multiseries clone (81microm) resulted in up to 70x lower toxin levels in oysters compared to mussels, which was attributed to differential feeding selectivity. Mussels were unable to discriminate between long- and short-celled P. multiseries clones from a mixed suspension, whereas oysters were previously shown to preferentially reject long cells (>70microm) in pseudofeces. Both bivalves selectively rejected P. multiseries cells from mixed suspensions containing a flagellate but not another diatom. AE of organics from P. multiseries cells by oysters and mussels was comparably low (42 and 39%, respectively) and thus unlikely to explain their differential DA accumulation. CR and DA uptake by oysters were negligible at <or=4 degrees C but increased with increasing temperature up to 18 degrees C, although mean DA levels barely attained the regulatory limit (20microg g(-1)) when oysters were exposed to long P. multiseries cells. The maximum DA levels accumulated by mussels (320microg g(-1)) and oysters (44microg g(-1)) exposed to short P. multiseries cells in our study support the inter-specific differences in toxicity during Pseudo-nitzschia blooms, which are expected to be exacerbated at lower temperatures and when long cells or chains are dominant. Additionally, when alternate, non-diatom phytoplankton species are present, both bivalves can feed selectively and thus accumulate much lower DA levels than those predicted from their overall CRs. Our results provide support for the evaluation of species-specific management of DA-contaminated shellfish and need to be considered in modeling DA toxin kinetics of the two target species.
Authors:
Luiz L Mafra; V Monica Bricelj; Christine Ouellette; Stephen S Bates
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-01-25
Journal Detail:
Title:  Aquatic toxicology (Amsterdam, Netherlands)     Volume:  97     ISSN:  1879-1514     ISO Abbreviation:  Aquat. Toxicol.     Publication Date:  2010 Apr 
Date Detail:
Created Date:  2010-03-08     Completed Date:  2010-06-02     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8500246     Medline TA:  Aquat Toxicol     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  160-71     Citation Subset:  IM    
Affiliation:
Institute for Marine Biosciences, National Research Council, 1411 Oxford St., Halifax, NS, B3H 3Z1, Canada. mafrajr@gmail.com <mafrajr@gmail.com>
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MeSH Terms
Descriptor/Qualifier:
Animals
Biomechanics / physiology
Crassostrea / physiology*
Diatoms / metabolism*
Eating / physiology
Kainic Acid / analogs & derivatives*,  pharmacokinetics,  toxicity
Mytilus edulis / physiology*
Neurotoxins / pharmacokinetics*,  toxicity
Seawater
Chemical
Reg. No./Substance:
0/Neurotoxins; 14277-97-5/domoic acid; 487-79-6/Kainic Acid

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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