title: Does the marine biotoxin okadaic acid cause DNA fragmentation in the blue mussel and the pacific oyster?
abstract: Two bivalve species of global economic importance: the blue mussel, Mytilus edulis and the pacific oyster, Crassostrea gigas were exposed in vivo, to the diarrhoetic shellfish toxin okadaic acid (OA), and impacts on DNA fragmentation were measured. Shellfish were exposed using two different regimes, the first was a single (24 h) exposure of 2.5 nM OA (∼0.1 μg/shellfish) and algal feed at the beginning of the trial (T0), after which shellfish were only fed algae. The second was daily exposure of shellfish to two different concentrations of OA mixed with the algal feed over 7 days; 1.2 nM OA (∼0.05 μg OA/shellfish/day) and 50 nM OA (∼2 μg OA/shellfish/day). Haemolymph and hepatopancreas cells were extracted following 1, 3 and 7 days exposure. Cell viability was measured using the trypan blue exclusion assay and remained above 85% for both cell types. DNA fragmentation was examined using the single-cell gel electrophoresis (comet) assay. A significant increase in DNA fragmentation was observed in the two cell types from both species relative to the controls. This increase was greater in the pacific oyster at the higher toxin concentration. However, there was no difference in the proportion of damage measured between the two cell types, and a classic dose response was not observed, increasing toxin concentration did not correspond to increased DNA fragmentation.
authors.affiliation: School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland; Environmental Research Institute, University College Cork, Cork, Ireland. Electronic address: mc_moira@yahoo.co.uk.
authors.forename: Moira
authors.initials: M
authors.lastname: McCarthy
authors.affiliation: School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland; Environmental Research Institute, University College Cork, Cork, Ireland.
authors.forename: John
authors.initials: J
authors.lastname: O'Halloran
authors.affiliation: School of Food and Nutritional Sciences, University College Cork, Cork, Ireland.
authors.forename: Nora M
authors.initials: NM
authors.lastname: O'Brien
authors.affiliation: Department of Pharmacology and Therapeutics, University College Cork, Cork, Ireland; Environmental Research Institute, University College Cork, Cork, Ireland.
authors.forename: Frank F N A M
authors.initials: FFNAM
authors.lastname: van Pelt
mesh_terms: D000818:Animals; D020552:Comet Assay; D049896:Crassostrea / Q000187:drug effects* / Q000235:genetics; D053938:DNA Fragmentation / Q000187:drug effects*; D008387:Marine Toxins / Q000633:toxicity*; D049880:Mytilus edulis / Q000187:drug effects* / Q000235:genetics; D019319:Okadaic Acid / Q000633:toxicity*
chemical_list: D008387:Marine Toxins; D019319:Okadaic Acid
keywords: Algal toxins; DNA; Filter feeding; Genotoxicity; Mussel; Okadaic acid; Oyster