Speaker: Helen Poynton

THE BREN SCHOOL OF Environmental Science & Management
at the University of California, Santa Barbara


Helen Poynton
Postdoctoral Fellow
U.S. Environmental Protection Agency

Wednesday, Feb. 25
12:30 - 1:30 p.m.
Bren Hall 1414

"Small, Smaller, Nano! A Daphnia Magna DNA Microarray for Biomarker Discovery

and Environmental Monitoring of Metal-based Nanomaterials."

Hosted by Patricia Holden



Nanotechnology research and development has created unprecedented advances in many commercial and industrial sectors. However, this rapidly growing field has also created an urgent need for toxicological studies addressing the exposure potential and ecological effects of nanomaterials once they are introduced into the environment. Recent studies have shown that slight changes in the coatings or size of nanoparticles can drastically alter their chemical properties and toxicity. Our research focuses on characterizing the exposure potential of nanoparticles and addressing how differences in coatings and size affect their bioavailability to aquatic invertebrates. Aquatic invertebrates are well suited for these studies as they serve as an avenue for nanomaterials to enter the food web. In addition, they are sensitive indicators of toxicity to many chemicals, including nanomaterials. 

The integration of genomic techniques, including DNA microarrays, into environmental monitoring has presented many exciting possibilities to investigate chemical exposure. By profiling thousands of genes in one experiment, microarrays can provide an expression signature or fingerprint specific for one chemical. Previous research illustrated the ability of a DNA microarray for the bioindicator species Daphnia magna to distinguish metal toxicants based on their gene-expression fingerprint. When applied to a field setting in California, the gene-expression fingerprints successfully predicted the toxicants present in water samples collected from abandoned copper mines. Our current challenge is to apply this technology to study nanoparticle exposure and bioavailability. We are using the D. magna microarray to reveal biomarkers that respond specifically to metal-based nanoparticles and can distinguish between exposure to the nanoparticles and their corresponding metal ions. These biomarkers will help us understand how environmental factors and nanoparticle characteristics affect the bioavailability of nanomaterials.



Helen Poynton took an early interest in environmental science with a hope to better understand the environmental factors that cause disease. With an undergraduate degree from Temple University and undergraduate research in cancer cell biology, Helen enrolled in the UC Berkeley graduate program in Nutritional Sciences and Toxicology. At Berkeley, she focused on ecosystem health with the rationale that healthy ecosystems will create better environments both for wildlife and people. Her graduate work focused on developing gene expression biomarkers for the aquatic invertebrate Daphnia magna and demonstrating the potential of genomics in ecotoxicology. That work led to three peer-reviewed articles in Environmental Science and Technology and a book chapter reviewing the promise and challenges of genomics in environmental science.  After receiving her PhD from UC Berkeley in 2007, Helen joined the Molecular Indicators Research Branch of the U.S. Environmental Protection Agency in Cincinnati, Ohio, as an Oak Ridge Institute–sponsored post-doctoral fellow. She is currently studying the effects of nanomaterials on gene expression and developing biomarkers that will help predict the exposure potential and potential risk from nanomaterials in the environment as this technology takes center stage in the 21st century. 



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