Genomics of Fathead Minnow Pb Toxicity in Different Water ChemistriesEPA Grant Number: F07D10649
Title: Genomics of Fathead Minnow Pb Toxicity in Different Water Chemistries
Investigators: Mager, Edward M.
Institution: University of Miami
EPA Project Officer: Hahn, Intaek
Project Period: August 22, 2007 through August 31, 2010
RFA: STAR Graduate Fellowships (2007) RFA Text | Recipients Lists
Research Category: Ecological Assessment , Academic Fellowships , Fellowship - Environmental Toxicology
The establishment of water quality criteria for lead (Pb) continues to rely principally on relationships between mortality and water hardness despite mounting evidence that other parameters (e.g. dissolved organic carbon (DOC) and alkalinity) may hold equal or greater importance in mediating toxicity. Moreover, the extent to which the influences of water chemistry are consistent during acute and chronic exposures remains unclear. This project seeks to define the key water chemistry parameters influencing chronic Pb toxicity and to identify robust molecular markers of Pb exposure and effect in the fathead minnow (Pimephales promelas). The ultimate goal of this research is to facilitate improved environmental management and risk assessment decisions for Pb through the development of genomic methodologies and a new chronic Biotic Ligand Model (BLM).
To analyze the effects of various water chemistry parameters on Pb toxicity fathead minnows will be exposed to waterborne Pb under flow-through conditions using low-ionic strength base water modified by addition of concentrated stock solutions. Concentration-dependent gene expression responses as well as full-life cycle, chronic responses (in the context of ambient water quality) will be examined by microarray analysis. Reproductive endpoints will also be monitored for the full-life cycle exposure with the aim of establishing links between early gene expression responses and ecologically relevant chronic effects. Tissue-specific gene expression responses will be examined by whole mount in situ hybridizations to identify the principal target organs of toxicity. To examine a potential anemic response to Pb, metabolic rates and sustained aerobic performance will be determined using an automated swim-tunnel respirometer. Neurological effects will be evaluated by assessing behavioral endpoints such as startle response, prey capture ability and/or performance from a memory alternation task.
These efforts are anticipated to reveal signature molecular responses that will greatly improve the predictive toxicology of Pb by accounting for variances in local water conditions. It is predicted that DOC and carbonate ions will afford the greatest protection against chronic waterborne Pb toxicity. The underlying mechanisms of Pb toxicity, which may hold significant relevance to human exposures, are expected to be more clearly defined and tied directly to physiological responses thereby improving the ability to predict outcomes of ecological significance.