Despite over 30 years of effort, assessing the impacts of chemical contaminants on aquatic organisms and identifying the causes of ecological impairment still represent a challenging problem. Current diagnostic methods rely upon either monitoring of a limited number of contaminants or the use of relatively insensitive bioassays, such as whole effluent toxicity (WET) tests and toxicity identification evaluation (TIE) using acute toxicity as an endpoint. These approaches are resource intensive and limited in their ability to identify toxicants. Recent developments in molecular biology are providing new approaches for assessment of effects and identification of responsible contaminants. In this proposal, the PI will develop a new method, molecular TIE (mTIE), which uses gene expression as a ?fingerprint? to identify the contaminant(s) to which an organism has been exposed. As a test organism that is amenable to high throughput testing, they propose to use the freshwater aquatic eco-indicator model organism, Daphnia magna, which is ideal for this work because of its small size, easy culture, rapid generation time, and sensitivity to a diversity of contaminants. The proposed research will test an innovative new technology that will allow for rapid contaminant evaluation in environmental samples and has the potential to transform water quality assessment. The project will proceed in three phases; first, they will establish a mTIE biomarker suite for contaminants likely to be present in freshwater sites; second, they will assess the mTIE in simulated field conditions and make necessary modifications to increase likelihood of robust field performance; and finally they will test the mTIE biomarker suite in a series of field situations.
The intellectual merits of the proposed research are related to the development of a suite of molecular investigative tools that can be used for evaluation of field samples. To achieve their objectives, they will conduct controlled laboratory studies with known doses of toxicants and assess confounding factors that could be encountered under field conditions prior to applying the new technique to samples from well characterized sites. In the first phase of the project, they will carry out controlled laboratory studies to develop the necessary database of gene expression ?fingerprints? for contaminants likely to be found in environmental samples. They have already carried out exposures to over thirty common pollutants and they will expand this dataset with exposures to additional selected chemicals that pose potential risks to aquatic ecosystem and are likely to be found at the field site(s) to be studied. Their goal is to identify a specific ?fingerprint? for each toxicant. In the second phase of the project, they will test the robustness of these ?fingerprints? in laboratory studies under a variety of environmental conditions likely to be found in the field. These include assessing the dose-dependent response of the ?fingerprints?, the effects of abiotic and biotic factors, and the specificity of the ?fingerprints? in a complex mixture of contaminants likely to be found at field sites. Finally, in the last phase of the project, they will apply this approach to field sites that are subjected to different pollutant sources or where evidence of ecological impairment has been observed but standard analytic approaches have failed to identify the cause. Together these studies will provide an assessment of the practical utility of the molecular TIE approach to identify contaminants in environmental samples. If successful, this approach has the potential to transform environmental assessment of freshwater ecosystems and provide a faster, more selective and cost effective approach to identify the causes of ecological impairment.
The broader impacts of the proposed research will be realized through close interactions with potential users of the technology and mentoring of students from groups that are traditionally underrepresented in science and engineering. Through a series of workshops and informal interactions, they will actively communicate our results to important stakeholder in the water resource community. They will also communicate the project?s results through conventional channels that include publication as peer-reviewed literature and presentations at scientific and public meetings. They will also engage in activities designed to recruit and retain graduate students from underrepresented populations through existing campus programs, including the NSF funded Berkeley EDGE, UC-AGEP, and ELP programs
