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TP12A Assessment in Tropical Ecosystems
() Cellular toxicological responses of the coral Madracis mirabilis to acute Irgarol 1051 exposure.
Owen, R1, 2, Downs, C3, Buxton, L2, Downs, A4, 1 UK Environment Agency, Bristol, U.K2 Bermuda Biological Station for Research, St Georges, Bermuda3 Envirtue Biotechnologies, Winchester, VA, U.S.A4 Yale University, New Haven, CT, U.S.A
ABSTRACT- Irgarol 1051 is a herbicide formulated with Cu in antifouling paints. There have been widespread reports of Irgarol 1051 contamination in temperate and tropical coastal waters. Our group and others have recently shown that Irgarol 1051 is a potent photosynthetic inhibitor at environmentally relevant concentrations in both isolated coral zooxanthellae (in vitro) and the intact coral symbiosis (in vivo) for a number of common coral species. We have also shown that Irgarol 1051 is comparatively more toxic to coral photosynthesis when compared to other common triazine and non triazine herbicides. Photosynthetic inhibition associated with Irgarol 1051 exposure is an important but predictable physiological response given the known photosystem II inhibitory mode of action for this herbicide. Further important toxicological responses have not however been investigated in corals (or indeed any other species). In order to address this we used cellular diagnostics to measure changes in 18 cellular parameters in algal and host fractions of the common branching coral Madracis mirabilis associated with in vivo 8 hour and 24 hour exposure to a nominal initial Irgarol 1051 concentration of 10 g L-1. Cellular toxicological responses measured were a) xenobiotic response (multixenobiotic resistance (MXR), CYP P450 -3 class, CYP P450 - 6 class, GST ; b) oxidative damage and response (Cu / Zn / Mn SOD , GPx, catalase, protein carbonyl); c) metabolic homeostasis (sHsp, PPO , ferrochelatase, heme oxygenase); d) protein metabolic condition (Hsp 60, Hsp 70, ubiquitin, ubiquitin ligase). Responses to acute Irgarol 1051 exposure included increased algal and host MXR, host PPO, host heme oxygenase, total protein carbonyl and algal Cu / Zn SOD, decreases in host GPx and large decreases in host CYP 450 3 and 6 class, host ferrochelatase and host catalase. Related implications of Irgarol 1051 exposure to coral health are discussed.
Key words: Antifoulant, Coral, Herbicide, Biomarkers
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