title: Dynamics of protein phosphatase gene expression in Corbicula fluminea exposed to microcystin-LR and to toxic Microcystis aeruginosa cells.
abstract: This study investigated the in vivo effects of microcystins on gene expression of several phosphoprotein phosphatases (PPP) in the freshwater clam Corbicula fluminea with two different exposure scenarios. Clams were exposed for 96 h to 5 μg L(-1) of dissolved microcystin-LR and the relative changes of gene expression of three different types of PPP (PPP1, 2 and 4) were analyzed by quantitative real-time PCR. The results showed a significant induction of PPP2 gene expression in the visceral mass. In contrast, the cyanotoxin did not cause any significant changes on PPP1 and PPP4 gene expression. Based on these results, we studied alterations in transcriptional patterns in parallel with enzymatic activity of C. fluminea for PPP2, induced by a Microcystis aeruginosa toxic strain (1 × 10(5) cells cm(-3)) during 96 h. The relative changes of gene expression and enzyme activity in visceral mass were analyzed by quantitative real-time PCR and colorimetric assays respectively. The clams exhibited a significant reduction of PPP2 activity with a concomitant enhancement of gene expression. Considering all the results we can conclude that the exposure to an ecologically relevant concentration of pure or intracellular microcystins (-LR) promoted an in vivo effect on PPP2 gene expression in C. fluminea.
authors.affiliation: CIIMAR/CIMAR, Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Rua dos Bragas 289, 4050-123 Porto, Portugal. jcmmartins@hotmail.com
authors.forename: José Carlos
authors.initials: JC
authors.lastname: Martins
authors.forename: João
authors.initials: J
authors.lastname: Machado
authors.forename: António
authors.initials: A
authors.lastname: Martins
authors.forename: Joana
authors.initials: J
authors.lastname: Azevedo
authors.forename: Luís
authors.initials: L
authors.lastname: OlivaTeles
authors.forename: Vitor
authors.initials: V
authors.lastname: Vasconcelos
mesh_terms: D000818:Animals; D049874:Corbicula / Q000201:enzymology* / Q000382:microbiology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D052998:Microcystins / Q000494:pharmacology*; D046931:Microcystis / Q000737:chemistry / Q000472:pathogenicity*; D054645:Protein Phosphatase 1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D054648:Protein Phosphatase 2 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: D004791:Enzyme Inhibitors; D052998:Microcystins; C078588:microcystin; D054645:Protein Phosphatase 1; D054648:Protein Phosphatase 2