Development of novel biomarkers of fish exposure to environmental contaminants
Abstract
Biomarkers of contaminant exposure and effect are useful tools in determining the degree to which toxic substances impact fish populations. Their usefulness, however, is often impeded by their lack of a direct association with chemical mode(s) of toxic action and their lack of chemical specificity. Therefore, the need to develop novel, effects-based biomarkers of fish exposure to contaminants exists. The advent of genomic, proteomic and physiological sensing technologies have allowed contaminant-induced effects to be determined on a broad scale and are well-suited to facilitate biomarker discovery. We utilized microarrays and two-dimensional gel electrophoresis combined with matrix assisted laser desorption/ionization time-of-flight (MALDI TOF/TOF) mass spectrometry in an effort to identify potential gene and protein biomarkers of fish contaminant exposure in male largemouth bass (Micropterus salmoides) and fathead minnows (Pimephales promelas). We also assessed the utility and sensitivity of a real-time biomonitor of oxygen consumption by fathead minnow embryos to detect the presence of aquatic contaminants. Proteomic analyses of largemouth bass hepatic tissues after 96 hours of exposure to one of five chemicals revealed changes in the expression of proteins associated with cellular ion homeostasis (toxaphene), oxidative stress (phenanthrene, PCB 126), and energy production including glycolysis (cadmium chloride, atrazine) and ATP synthesis (atrazine). Microarray analysis of these same tissues suggested that changes in the expression of genes associated with ethanol metabolism (cadmium chloride), protein biosynthesis (cadmium chloride, PCB 126, phenanthrene) and mRNA transcription and mRNA export from the nucleus (PCB 126, phenanthrene) were induced. Transcripts involved with one-carbon compound metabolism (PCB 126, phenanthrene, toxaphene) were likewise altered while little transcriptional response was observed in atrazine exposed fish. A comparison of the transcriptional response of largemouth bass and fathead minnows was also evaluated utilizing microarrays. This investigation revealed that the two models had little in common with regard to their gene expression responses. The whole organism biomonitor of water quality was able to detect oxygen consumption changes in fathead minnow embryos in the presence of pentachlorophenol, cadmium chloride, atrazine, carbonyl cyanide m-chlorophenylhydazone (CCCP), and rotenone, but did not detect the presence of malathion. These trials have indicated that this system is more sensitive to the presence of contaminants than other biomonitors in use. In all, this work has identified several gene transcripts and proteins that have the potential to serve as biomarkers of fish contaminant exposure and effect. It has also established a physiologically-coupled biomonitor system as a sensitive and reliable tool for the detection of aquatic contaminants.
Degree
Ph.D.
Advisors
Sepulveda, Purdue University.
Subject Area
Molecular biology|Ecology|Environmental science
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