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PM05 Aquatic Vertebrate/Invertebrate Toxicology
(PM108) Effects of municipal sewage effluent on immune function of rainbow trout (Oncorhynchus Mykiss).
Müller, C1, Ruby, S2, Fournier, M1, 1 INRS-Institut Armand-Frappier, Pointe-Claire, Québec, Canada2 Concordia University, Montréal, Québec, Canada
ABSTRACT- Sublethal stressors such as pollution cause reduction in growth, resistance to disease reproductive function and behavioural capabilities and have long-term consequences for survival of fish populations. Contamination of the aquatic environment with polluants such as heavy metals, dioxins, polychlorined biphenyls and pesticides originates from anthropogenic sources such as industries, agriculture and city sewage. The aim of this study is to examine how an exposure of rainbow trout (Oncorhynchus mykiss) to municipal effluents, released by the Outaouais sewage treatment plan, at concentrations comparable to those reported from polluted natural waters interferes with immunological functions. Four groups of 15 juvenile rainbow trout were exposed to 0.1%, 1% and 10% concentrations of Outaouais municipal effluent for a period of 30 days. Fish kidneys were collected and three immunological parameters were using as biomarker of toxicity corresponding to phagocytosis functional assay, lymphoblastic transformation and also cell cytotoxicity. Phagocytosis by kidney macrophages was measured by flow cytometry using fluorescent latex beads. Proliferative responses to phytohemagglutinin (PHA) and lipopolysaccharide (LPS) by kidney lymphocytes were determined by 3H-thymidine incorporation into replicating DNA. The cell cytotoxicity assays were performed, in flow cytometry, with NK cells and YAC-1 transformed cells as target. The percentage of phagocytic activity was significantly decreased for fish exposed to a 10% concentration relative to the control group, suggesting a immunosuppressive effect. LPS stimulation of lymphocyte proliferation was decreased in trout exposed to 1% and 10% effluent concentrations. PHA stimulation of lymphocyte proliferation was decreased in trout exposed to 1% effluent concentration. These data suggest that lymphocytes are suppressed by effluent exposure. The Nk activity was increased in trout exposed to 10% effluent concentration, suggesting a immunostimulation of NK cells. Because water is a primarily necessity and can cause important diseases for many organisms, it appear strongly important to take care of the resource.
Key words: immunotoxicity, municipal effluents, rainbow trout, phagocytosis
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