Transcriptomes: A Signature for Common Bottlenose Dolphin Exposure and Health
IAAAM 2013
Annalaura Mancia1,2*; James C. Ryan3; Frances M. Van Dolah3; John R. Kucklick4; Teresa K. Rowles5; Randall S. Wells6; Patricia E. Rosel7; Aleta A. Hohn8; Lori H. Schwacke3
1 Department of Life Sciences and Biotechnology, University of Ferrara, 44121, Ferrara, Italy; 2Marine Biomedicine and Environmental Science Center, Medical University of South Carolina, Hollings Marine Laboratory, Charleston, SC, 29412, USA; 3NOAA, National Ocean Service, Hollings Marine Laboratory, Charleston, SC, 29412, USA; 4National Institute of Standards and Technology, Hollings Marine Laboratory, Charleston, SC, 29412, USA; 5NOAA, National Marine Fisheries Service, Office of Protected Species, Silver Spring, MD, 20910, USA; 6Chicago Zoological Society, c/o Mote Marine Laboratory, Sarasota, FL, 34236, USA; 7National Marine Fisheries Service, Southeast Fisheries Science Center, Lafayette, LA, 70506 USA; 8NOAA, National Marine Fisheries Service, Southeast Fisheries Science Center, Beaufort, NC, 28516, USA
Abstract
As top level predators, bottlenose dolphins (Tursiops truncatus), are particularly sensitive to chemical and biological toxins that accumulate and biomagnify in the marine food chain. A dolphin's exposure to such toxins can be assessed using standard analytical methods, but it is costly and requires the collection of multiple tissue samples. These methods inferred toxic effects through the comparison of exposure measures to known toxic thresholds that were usually developed in different species. We are currently investigating the potential of screening for multiple contaminant and/or algal toxin exposure through their associated immunological and/or endocrine perturbations in bottlenose dolphins using microarray technology and gene expression profile analysis. If successful, the gene expression profile analysis could provide a cost-effective means to screen for indicators of chemical and biological toxin exposure as well as disease status in dolphins, and potentially other cetaceans.
A dolphin oligo microarray representing 24,418 unigene sequences was used to analyze blood samples collected from 47 dolphins sampled during capture-release health assessments from five geographic locations (Beaufort, NC, Sarasota Bay, FL, Saint Joseph Bay, FL, Sapelo Island, GA and Brunswick, GA). Organochlorine pesticide and polychlorinated biphenyl congener concentrations were determined in blubber biopsy samples from the same animals. Here we present the evidence of how strongly chemical contaminants impact dolphin gene expression.
A small group of samples (10 males and 8 females) with the highest and the lowest measured values of contaminants in their blubber were used as strata to search for genes that might indicate the differential gene expression of the exposure extremes. The resultant gene set could be a signature of contaminant exposure.
In order to test this hypothesis we next investigated the blood transcriptomes of the remaining dolphin samples using machine-learning approaches, such as Knn classifier and Support Vector Machines. Using the derived gene set, the algorithms worked very well at classifying dolphins according to the contaminant load accumulated in their 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.
Acknowledgements
This study was performed under permits 932-1489-10 and 522-1785 from the NMFS and supported by awards from the NOAA Oceans and Human Health Initiative, Dolphin Quest, Georgia Aquarium, Disney's Animal Programs, Morris Animal Foundation's Betty White Wildlife Rapid Response Fund, and NOAA Fisheries Service.
* Presenting author