title: Microcystin accumulation and antioxidant responses in the freshwater clam Diplodon chilensis patagonicus upon subchronic exposure to toxic Microcystis aeruginosa.
abstract: We investigated the accumulation and toxicity of microcystin-LR (MCLR) in the digestive gland of the freshwater clam Diplodon chilensis patagonicus. Treated clams were fed with a toxic strain of Microcystis aeruginosa (NPJB1) during 6 weeks and control clams received the non-toxic strain NPDC1. Filtration rate was estimated for both groups. Toxic effects were evaluated through the hepatosomatic index (HSI) and different oxidative stress biomarkers, lipid peroxidation (content of thiobarbituric reactive substances-TBARS), protein oxidation (carbonyl groups) and reduced glutathione (GSH) levels, and enzymatic activities of superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST). The extractable MCLR measured by ELISA in digestive gland extracts showed little or no change during the first 3 weeks and increased significantly at weeks 5 and 6. HSI was reduced by 30% in treated clams at weeks 5 and 6. No significant oxidative damage to lipids or proteins was. All the antioxidant defense parameters analyzed were significantly increased at week 5 or 6. GSH increased in treated clams at week 5, reaching 62% increase at week 6. SOD, CAT and GST activities were significantly increased in treated clams by 50%, 66% and 60%, respectively, at the end of the experiment. D. chilensis patagonicus can be exposed to prolonged cyanobacterial blooms accumulating significant quantities of MCLR, which could be a risk for mammals and birds, which feed on this species and, in a lesser extent, to humans.
authors.affiliation: Department of Biological Chemistry, College of Exact and Natural Sciences, University of Buenos Aires, Argentina. sabatini@bg.fcen.uba.ar
authors.forename: Sebastián E
authors.initials: SE
authors.lastname: Sabatini
authors.forename: Beatríz M
authors.initials: BM
authors.lastname: Brena
authors.forename: Carlos M
authors.initials: CM
authors.lastname: Luquet
authors.forename: Magdalena
authors.initials: M
authors.lastname: San Julián
authors.forename: Macarena
authors.initials: M
authors.lastname: Pirez
authors.forename: María Del
authors.initials: MD
authors.lastname: Carmen Ríos de Molina
mesh_terms: D000818:Animals; D049872:Bivalvia / Q000187:drug effects / Q000378:metabolism* / Q000382:microbiology; D002374:Catalase / Q000378:metabolism; D005618:Fresh Water / Q000737:chemistry / Q000382:microbiology; D005978:Glutathione / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D015227:Lipid Peroxidation / Q000187:drug effects; D008070:Lipopolysaccharides / Q000378:metabolism; D008387:Marine Toxins; D052998:Microcystins / Q000378:metabolism / Q000633:toxicity*; D046931:Microcystis / Q000472:pathogenicity*; D018384:Oxidative Stress; D013482:Superoxide Dismutase / Q000378:metabolism; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000378:metabolism / Q000633:toxicity*
chemical_list: D008070:Lipopolysaccharides; D008387:Marine Toxins; D052998:Microcystins; D017392:Thiobarbituric Acid Reactive Substances; D014874:Water Pollutants, Chemical; D002374:Catalase; D013482:Superoxide Dismutase; D005982:Glutathione Transferase; C057862:cyanoginosin LR; D005978:Glutathione