Impact/Purpose:

Subtask #1 - Changes in Tissue Gene Expression

This task aims to develop molecular methods to

1. diagnose exposures to specific chemical compounds or families of related compounds;

2. detect the estrogenic potential of surface waters;

3. accurately measure biological responses in aquatic organisms, thereby, determining bioavailability of temporal or persistent organic compounds, pesticides, endocrine disrupting compounds in streams, lakes, and large rivers;

4. provide a reliable means to detect and identify previously uncharacterized genes that are transcriptionally responsive to specific pesticides and other chemical compounds and

5. to use the novel technique (developed in MERB) of successive gill resections (single animal model) to provide molecular indicator data, before and after, environmental exposure.

Subtask #2 - Indicators of Genetic Damage

1. A primary objective will be a comparison of the sensitivity of cellular indicators of genetic damage in model stream fish using controlled laboratory exposures. The work will progress to field applications of the measurements in fish in the Little Miami River Watershed (EERD Near Site), and/or other field sites. The ultimate objective will be the development of an indicator both diagnostic of exposure to genotoxic chemicals and informative of the mutagenic frequency of aquatic ecosystem resources. This development will be an advantage for comparative exposure assessments in regional studies. Correlation of this indicator coverage with those of other condition indicators may be informative regarding the vulnerability of specific aquatic receptors to further stressor exposures.

Description:

Accurate and precise characterization of exposure of aquatic ecological resources to chemical stressors is required for ecological risk assessment. Within this assessment, the study of the vulnerability of these resources requires comparative exposure assessments across watersheds and regions which, in turn, require sensitive, diagnostic indicators of specific stressors.
Advances in molecular biology are allowing the development of new diagnostic indicators of exposure. These indicators are bringing entirely new data to ecological risk assessment. Not only are tools being made available to study the intensity and duration of exposure to specific chemicals, but also new windows on bioavailability, surrogate ecosystem use and field indicator measurement are being opened. For example, detection of changes in liver gene expression in field exposed fish can allow measurement of total exposure to estrogenic compounds. Overall, this indicator development is expected to contribute substantially to the detection of pesticides, metals and endocrine disrupting compounds in stream and large river ecosystems. Such research will support the construction of regional stressor profiles and provide methods for comparative exposure assessment.
This research is being carried out by the conduct of three subtasks. Subtask 1 is directed toward the development of fish tissue gene expression indicators for the measurement of exposure to estrogenic compounds, metals, polycyclic aromatic hydrocarbons and modern pesticides such as alachlor and atrazine. Subtask 2 is directed toward the application of genetic damage indicators to regional field studies. Subtask 3 involves the development of protein and DNA adducts of pesticides as indicators of exposure and tools for the measurement of bioavailability.

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