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My research team is currently focused on the following four areas:
(1) Interactions of nanomaterials with ubiquitous environmental contaminants
As nanomaterial use increases the inevitable environmental release of these materials leaves us with questions regarding their effects on environmental health and safety. While numerous publications have examined the toxicity of nanomaterials themselves, the highly sorptive nature of many nanomaterials warrants investigation of their interactions with contaminants already present in the environment. Using single-walled carbon nanotubes as a model nanomaterial, we are examining how the interactions of these materials with other organic contaminants may influence downstream responses. Preliminary data indicates that though these materials effectively sorb contaminants, they may still be bioavailable to aquatic biota, especially during oral exposures.
(2) Gastrointestinal systems as a target for xenobiotic and nutrient stress
While much aquatic toxicology research focuses on waterborne uptake of contaminants and biochemical responses in other organs, the GI represents a large epithelial surface likely to be a target of hydrophobic contaminants that are more likely to bioaccumulate in food chains. The GI can also be susceptible to nutrient depletion in the presence of contaminants as physical binding of nutrients may prevent their uptake or modulation of uptake transporters and processing enzymes can cause nutrient deficiency. Finally, while much research on endocrine active compounds focuses on brain as a target, the GI system is extensively involved in endocrine function, yet little is understood about its interplay with other endocrine systems. While this line of research is obviously important for understanding the impacts of hydrophobic organic contaminants on fish toxicity, it may also have applications in obesity research.
(3) Receptor binding and activation assays as contaminant screening tools
Ubiquitous contamination of aquatic environments with mixtures of chemicals makes it difficult to pinpoint individual compounds responsible for effects on organisms. Chemical analysis of water samples can be expensive and often results in detection of hundreds of analytes leaving investigators pondering which contaminants are influencing observed effects. Receptor binding and activation assays have emerged as quick and inexpensive techniques to assess the collective effect of chemical mixtures on specific receptors that can be linked to phenotypic effects. Based on results from our team at the University of Florida, we have shown these assays are activated by extremely low concentration extracts from field collected samples. We have successfully used these assays in local and international settings which demonstrates their wide ranging application. For example, we have recently received a small contract with the state of Florida to use these assays in their endocrine disruptor survey this coming year. For the past two years I have traveled to Haiti to collect samples from rural and urban centers to determine what level of exposure people from this resource poor country may be experiencing.
(4) Behavior as an indicator of low level toxicity
Though much of our environmental risk assessments are based on overt toxicity data, low level exposures may still result in sub lethal toxicity with population level consequences. Behaviors such as feeding, reproductive, swimming, and predator avoidance behaviors are all crucial for fish population survival and subtle effects on these endpoints are often overlooked during standardized acute and chronic exposure studies. Using assays targeting these behaviors we are able to determine how contaminants may alter these sensitive endpoints and determine if aquatic organisms may be at risk during sublethal exposures.
Keywords: Aquatic Toxicology; Nanomaterials; Environmental Toxicology; Pharmaceuticals; Endocrine Disruptors; Metals; Organic contaminants; Pesticides; Behavioral Toxicology
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