Elucidating the Role of Toxin Transporter Proteins in conferring chemical tolerance in Fish

The proposed marine ecotoxicology research is aimed at elucidating the influence of environmental chemicals, including the algal toxin saxitoxin and agricultural pesticides, on the expression and function of toxin transport proteins (i.e. multi drug resistance proteins) in killifish. The traditional detoxification paradigm describes the biotransformation of chemicals by drug metabolizing enzymes to more easily excretable hydrophilic forms. That the excretion of these metabolites is an energy dependent process facilitated by toxin transport proteins is currently under appreciated . Insufficient attention has been focused on the influence of transporters on disposition, bioavailability, and toxicity of anthropogenic organic contaminants. We will elucidate the role ABC toxin transport proteins play in the multixenobiotic resistance phenotype observed in wild populations of killifish which are highly exposed to putative substrates, such as organic pollutants, in their aquatic environment.


Genomic and Metabonomic research to examine the response of Atlantic salmon to the natural toxin saxitoxin. Saxitoxin is produced by phytoplankton during red tide events and is responsible for paralytic shellfish poisoning. Fish can generally tolerate low levels of
saxitoxin, although fish kills do rarely occur following red tides. Using a microarray generated by our National Research Council collaborators, we are examining the expression of 4000 genes in salmon exposed to saxitoxin. In collaboration with National Research Council colleagues, we are also undertaking a metabonomic study to fingerprint the hepatic metabolites generated during saxitoxin exposure to shed
light on the chemical defense strategies these fish employ.


Elucidate the cellular defense mechanisms responsible for chemical resistance in a population of estuary fish (Fundulus heteroclitus) inhabiting the Sydney tar ponds in Nova Scotia. This study will be undertaken in collaboration with analytical chemists from St. Mary's University and marine ecologists from University of Cape Breton College. We will examine the role of a suite of detoxification enzymes (cytochrome P450s, glutatione-S-transferase, etc.) and multidrug resistance transporters (P-glycoproteins, MRPs, etc.) in providing chemical tolerance in these fish.


Intertidal Ecotoxicology with applications to marine management

Develop biological indicators of contaminant exposure to monitor the effect of sewage contamination in Halifax Harbour. In collaboration with colleagues in the Department of Fisheries and Oceans we will select appropriate biological indictors to measure contaminant exposure at the community, organismal, and cellular levels. This baseline
data will be used to track recovery of the Halifax Harbour habitat over the next decade as sewage treatment is initiated in the near future.


Developing a geographic information system (GIS) to map marine diversity and contaminants

For more than a decade, the Georgia Strait Alliance marine environmental advocacy group has collected scientifically rigorous intertidal diversity data using quadrat and transect technique at over 33 sites around Georgia Strait, British Columbia. Georgia Strait is the body of water separating Vancouver Island from the mainland and the majority of British Columbians live along its borders and watersheds. A geographic information system (GIS) will be developed of the Georgia Strait overlaying data from GSA's intertidal species diversity studies with Department of Fisheries and Oceans contaminant surveys, along with urban and industrial development, fishing management, oceanographic and census data. GIS is a powerful computational tool which aids in the identification of data patterns, temporal trends, and facilitates forecasting of future conditions. GIS will provide insight into which factors are associated with greatest species depletions, identify depleted sites in need of further clean up, and will be used to predict the environmental outcomes of a given pollution abatement or other marine management policy. This project will be undertaken in the ecotoxicology laboratory of Dr. Shannon Bard at Dalhousie University in collaboration with researchers at the Centre of Geographic Sciences (COGS) in Nova Scotia.



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