News and Highlights: October 2006

EPA funding to study the ecotoxicology of nanomaterials in fish

CWH researcher T. Henry and his colleagues in UT's Center for Environmental Biotechnology and Departments of Chemistry and Physics have been awarded EPA funding to study the bioavailability and toxicity of a ‘nanomaterial’ (C60 fullerene).

Use of nanomaterials in various industries is projected to increase dramatically in the future and environmental contamination by these materials is expected. Aquatic ecosystems are likely to become contaminated by C60 in the future and the potential for toxicity in aquatic organisms should be investigated.  The researchers' objectives are to investigate characteristics of aqueous C60 aggregates, the impact of dissolved organic material on behavior of these aggregates, and to evaluate bioavailability and toxicity of C60 (both aqueous C60 aggregates and dietary C60) in fish by assessing changes in gene expression, histopathology, and bioaccumulation of C60 in tissues.  Hypotheses are 1) bioavailability of aqueous C60 aggregates is impacted by nanoparticle characteristics and presence of dissolved organic material; 2) exposure of fish to C60 can be detected by changes in expression of biomarker genes; and 3) toxic effects of C60 in fish can be detected only after long-term chronic exposure. Zebrafish Danio rerio and channel catfish Ictalurus punctatus are the species that will be investigated in this research.

Approach: The initial phase of research will investigate the behavior of aqueous C60 nanoparticles and associate particle characteristics with bioavailability in larval zebrafish.  Particle characteristics and the influence of dissolved organic material (humic, fluvic acid) will be investigated by integration of analytical techniques including HPLC, LC-MS, laser desorption MS, Raman spectroscopy under liquid nitrogen (RUN), FTIR, and transmission electron microscopy.  A set of biomarker genes will be selected from microarray analyses and developed in an RT-PCR format to serve as biomarkers of C60 exposure in larval zebrafish.  Chronic toxicity of aqueous C60 aggregates will be investigated in zebrafish exposed from embryos to adult life stages, toxicity will be assessed by survival, growth, biomarker gene expression in specific tissues, and histopathology.  Biomarker genes identified in zebrafish will be adapted for use in channel catfish in an RT-PCR format and gene expression will be assessed in specific tissues of fish chronically exposed to aqueous or dietary C60.  In channel catfish, the bioaccumulation of C60 among tissues will be assessed and lesions will be examined by histopathology of specific tissues.

Expected results:  Expected results include clarification of the characteristics of aqueous C60 nanoparticles and the influence of dissolved organic material on their bioavailability and toxicity in fish.  Genes identified as biomarkers of C60 exposure will be developed for use as tools to investigate C60 toxicity in fish.  Chronic toxicity of C60 will be determined and the potential for C60 to bioaccumulate in specific tissues will indicate the potential for human exposure to occur after consumption of fish chronically exposed to C60 in the future.

EPA Research Category: Nanotechnology Research Grants Investigating Environmental and Human Health Effects of Manufactured Nanomaterials (EPA-G2006-STAR-F1—Toxicology)

Investigators: Theodore B. Henry (thenry8@utk.edu), Gary S. Sayler (sayler@utk.edu), and Fu-Min Menn (fmenn@utk.edu), Center for Environmental Biotechnology; Robert N. Compton (rcompton@utk.edu) Departments of Chemistry and Physics.

Proposed Project Period: August 1, 2006 – July 31, 2009

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