Abstract
Common bottlenose dolphins (Tursiops truncatus) have been proposed as potential biosensors for monitoring of emerging health hazards in the coastal marine environment. As mammals, they are susceptible to many of the same diseases and pathogens as humans, and as top level predators they are particularly sensitive indicators for chemicals and biotoxins that accumulate and biomagnify in the marine food chain. Prior investigations of bottlenose dolphins have provided insights into the trophic transfer and potential health effects of algal toxins, and have also warned of abnormally high levels of chemical contaminants in the coastal food web1,2. While these investigations have significantly advanced our understanding of potential exposure vectors as well as health risks from marine toxins and coastal pollutants, they have only come with considerable investment of effort and cost. The current state of technology requires a variety of biological samples (e.g., blood, urine, feces, blubber, skin) to be taken through capture-release health assessments3 in order to measure for even a limited suite of chemical or biological toxins. Limitations in available diagnostics and the logistical complexity of capture-release sampling to obtain the tissue samples necessary for current diagnostic assays necessitate a significant advancement of technology and tools in order to develop the bottlenose dolphin as a biosensor. We are currently investigating the potential for screening for contaminant and/or algal toxin exposure and associated immunological and/or endocrine perturbations using gene expression profile analysis. A newly developed dolphin oligo microarray (4 x 44k Agilent) representing 24,418 unigene sequences generated through both 454 and Sanger sequencing (publicly available at NCBI) was used to analyze blood samples from 74 dolphins collected from 4 different geographic locations (Beaufort, NC, Sarasota Bay, FL, Saint Joseph Bay, FL, Sapelo Island, GA and Brunswick, GA) during the years 2005–2010. Analysis of the gene expression data, in conjunction with chemical contaminant and algal toxin data, is currently underway. If successful, subsequent studies will attempt to identify gene expression profiles in other tissues (e.g., blubber).
The transcriptomic data analysis will be a first step towards identification of markers/patterns indicative of exposure to chemical contaminants as well as marine toxins and will promote an understanding of toxic mechanisms and/or pathways that are currently not well understood in marine mammals This information will not only be helpful for assessing health risks for dolphin populations, but may also suggest potential toxic pathways relevant to coastal human residents who may be exposed to the same compounds.
Acknowledgments
This study was performed under permits 932-1489-10 and 522-1785 from the National Marine Fisheries Service (NMFS) and supported by awards from the Oceans and Human Health Initiative (OHHI), Dolphin Quest, Georgia Aquarium, Disney's Animal Programs, Morris Animal Foundation's Betty White Wildlife Rapid Response Fund, and NOAA Fisheries Service.
References
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