Modulation of immune and antioxidant responses to Escherichia coli by azinphos-methyl in the freshwater mussel Diplodon chilensis

CASTRO J; BIANCHI V; VENTURINO A; LUQUET C

Buenos Aires

Congreso; 11th Biennial Meeting Society of Environmental Toxicology and Chemistry (SETAC) Latin America; 2015

SETAC LA

The aim of thiswork was to characterize the immune response and the oxidative balance in Diplodon chilensis upon exposure toenvironmentally relevant concentrations of AZM. Mussels were collected from an unpollutedsite and acclimated in laboratory for 3 days. Then, six groups were set: G1)Control: fed with the green algae Scenedesmus vacuolatus (SV, 3 days), G2)Solvent control (Acetone < 0.01%, 3 days), G3) Exposed to Escherichia coli (50,000 cell/mL, 3 days),G4) AZM (0.2 mg/L, 3 days), G5) Acetone (3 days) and then E. coli (3 days), G6) AZM (3 days) and then E. coli (3 days). Data were analyzed by one-way ANOVA and post hoccomparisons. Results: Total hemocyte number tends to increase in all treatedgroups respect to G1. Cell viability showed no variation between treatments. Hyalocyteproportion decreased in all treated groups, and was negatively modulated by AZMin G6. Granulocyte proportions showed the opposite trend to hyalocytes. Blustcells proportion increased significantly only in G5. Phagocytic activity inhyalocytes increased in all treated groups respect to G1, and was significantlyhigher in G4 compared with the rest. Phagocytic activity in granulocytesdecreased in G2-5 respect to G1, and was positively modulated by AZM in G6.Acid phosphatase activity increased in G3-6 respect to G1-2. Alkalinephosphatase and β-glucuronidase activity increased in all treated groupsrespect to G1, and was negatively modulated by AZM in G6 respect to G5. Lysosomalmembrane stability decreased in all treated groups respect to G1, and waspositively modulated by AZM in G6 respect to G5. Bacteriolytic activityincreased in G3, 5 and 6, while phenoloxidase activity decreased in G2, 4 and 6compared with the other groups. Gill GST activity increased in all treatmentsrespect to G1 and 2. Gill lipid peroxidation decreased in G4-6 respect to theother groups. Gill carboxyl esterase activity decreased in G4 and 6, respect toG2. Conclusion: Short-term exposure to AZM stimulates cellular response andpromotes granulocyte phagocytic activity and lysosomal membrane stability,while alkaline phosphatase and β-glucuronidase activities are inhibited by AZM.AZM alters cellular proportion towards granulocytes. Bacteriolytic activityincreases in all treatments with bacteria. Phenoloxidase activity decreases intreatments with pesticide or acetone. In gills, AZM stimulates antioxidantdefenses, while decreases carboxyl esterase activity.