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Aquatic Research Consortium

Issue

Many estuaries suffer from chemical contamination and nutrient-overload due to rapidly increasing human coastal populations, urbanization, industrial effluents, and agricultural run-off. The detrimental effects of nutrient-stimulated hypoxia and contaminants such as polycyclic aromatic hydrocarbons (PAHs) upon aquatic ecosystems have been well-documented. Currently, the effects of hypoxia on the plants and animals living in an ecosystem experiencing low oxygen levels coincide with a reduction of demersal fish and death of benthic fauna. Prolonged exposure to hypoxia results in behavioral or physiological changes such as increased ventilation frequency and cardiac output in both fish and crustaceans. While these responses are valuable indices of low oxygen conditions, they cannot serve as effective hypoxia biomarkers since they involve in situ measurements of the organisms and are not practical for monitoring. Indicators of hypoxia at the organism and cellular level are needed to assess the onset, duration and severity of chronic as well as intermittent hypoxia and its effect on biota. Genes that respond to hypoxia can potentially serve as indicators of hypoxic stress

Approach

Toxicogenomics combines the emerging technologies of genomics and bioinformatics to identify and characterize the actions of toxins in ecosystems. New opportunities for studying toxicological and ecosystem processes enable molecular biologists to examine genetic changes in expression. This is done simultaneously, using miniaturized chemical reaction areas to test DNA fragments, antibodies, or proteins (microarray technology). By investigating the effects of environmental contaminants on aquatic organisms in laboratory and field-based exposures, researchers attempt to link gene and protein expression profiles to biologically relevant endpoints such as reproduction and immune function. Eventually, the findings of these studies will help identify effects at higher levels of biological organization, such as communities and ecosystems. Such research will identify populations differing in their sensitivities to contaminant-induced immunotoxicity. The toxicogenomic approach allows investigators of diverse research disciplines to potentially discover structural DNA and RNA molecule sequences at a unique physical location in the genome This allows investigation of the molecular mechanisms behind resistant and sensitive populations. Ultimately, this shows genetic expression based on particular environmental conditions, and allows us to better understand heritable factors of complex traits such as behavior, disease resistance, and other attributes using experimental animal models.

Accomplishments

The Aquatic Research Consortium is a collaboration of scientists from the Gulf Coast Research Laboratory of The University of Southern Mississippi and from Southwest Texas State University. The studies' overall aim is to delineate specific genetic changes reflecting exposures to adverse environmental conditions. The proposed program will build on collective expertise in molecular genetics and toxicology, aquatic animal stock maintenance, refined exposure methodologies and toxicological response assessments. Ultimately, the data acquired and the models developed will be used to assess and monitor responses of both laboratory and feral fishes to environmental perturbations.

The project is developing genomic and proteomic tools in the Japanese medaka, Swordtails and Platyfish (Xiphophorus), and sheepshead minnows models. The project investigates the molecular responses of these fish models to hypoxia at the protein and gene expression levels. In addition, morphological, physiological, and molecular responses of fish early life stages (ELS) to environmentally-relevant levels of hypoxia and/or PAHs are being investigated. The research will uncover important similarities and differences in responses to hypoxia and PAHs among fish species, life stages, and several levels of biological organization (i.e., molecular, physiological, and morphological).

These studies, in their third year of funding, are delineating specific genetic changes reflective of exposures to adverse environmental conditions. The Consortium is building on collective expertise in molecular genetics and toxicology, aquatic animal stock maintenance, refined exposure methodologies and toxicological response assessments. The data acquired and the models developed are needed to assess and monitor responses of both laboratory and feral fishes to environmental perturbations. This information will assist federal agencies in assessing of the health of fish stocks and the effects of anthropogenic inputs, and will add fundamental knowledge on the genomic effects of environmental toxicants.

Management Policy Implications

By providing resource managers with sensitive early-warning indicators of potential problems with the population, Aquatic Research Consortium's (ARC) goal is development of stressor-specific diagnostic tools which indicate initial ecological change due to decreased water quality. Such indicators are of vital importance for effective management of ecological systems because they will allow proactive rather than reactive strategies for restoring ecosystem health. The indicators will be critical for rapidly evaluating the success of environmental remediation efforts. Ideally, the development of the next generation of molecular indicators, based on a genomics and proteomics approach, will detect environmental stress responses in fish, determine population differences in stress responses and link these indicators in individuals to responses at the population level.

Research Projects