Nanoparticle Transport to Oocytes and Toxicological Consequences in Fathead Minnows

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).0853707DenslowGrowing evidence suggests that many nanomaterials are taken up into fish species through the gills or digestive track. Once internalized, there is a potential for nanomaterials to cross into the blood stream, where they could pose a risk to internal organs including the ovary. Emerging literature and preliminary evidence in the current application suggest that nanomaterials may be capable of entering oocytes, potentially impacting embryonic development. There is a need to understand fundamental mechanisms that enable nanomaterial transport to oocytes, and the subsequent alterations of natural biological processes. It is currently understood that the physiological behavior of nanomaterials is largely impacted by adsorbed proteinaceous layers, which form upon seconds of exposure to biological media. Female fish that are actively reproducing have high serum levels (up to 20 mg/ml) of the egg yolk precursor protein, vitellogenin. This protein is a large phospholipoglycoprotein that has the capacity to bind to nanomaterials through various conduits, including areas of high negative charge and areas of high hydrophobicity. Vitellogenin is naturally targeted to developing oocytes and is imported into these oocytes via a vitellogenin-specific receptor. The overall hypothesis of this project is that vitellogenin-bound nanomaterials will be imported into yolk granules in developing oocytes and eventually merge with lysosomes. Furthermore, upon reaching this compartment certain nanomaterials could dissolve and leach into the cell causing toxicity for developing embryos. To address these hypotheses, the researchers have 3 specific aims: (1) Determine the effect of surface modification on uptake, cellular distribution and retention of nanomaterials in fish ovarian cultures. (2) Characterize the protein surface coating of nanomaterials exposed to male and female fathead minnow plasma. (3) Determine the distribution and reproductive toxicity of nanoparticles in vivo. To achieve these aims they will use model luminescent nanoparticulates, namely dye doped silica and quantum dots of carefully chosen size distributions and surface properties that will enable detailed analysis of the movement of these materials in vitro and in vivo. The proposed research will provide critical insights into the role of nanoparticulate properties on their translocation to oocytes. This information is anticipated to be highly important in the development of predictive models for nanotoxicity in fish species, and methods to mitigate potentially adverse outcomes of nanomaterial exposure to the environment. Cross-disciplinary training of graduate, undergraduate, and high school students at the interface between particle science and engineering and biology will be an essential part of the research program. The Southeast Alliance for Graduate Education and the Professoriate (SEAGEP), related Research Experience for Undergraduates (REU) programs, and established minority fellowship programs at the University of Florida will be leveraged to ensure diversity in the research program. Research results will be published in peer-reviewed journals and disseminated at national and international meetings. The investigators also plan to collaborate with national nanotechnology resources such as the Center for Nanotechnology in Society at Arizona State University and ICON at Rice to disseminate research results to the scientific and educational communities, and to society at large. The students will also participate in public outreach programs (e.g., UF's Engineering Fair)providing a conduit for them to engage the general public about the excitement of nanoscience and the importance of environmental stewardship. UF's Graham Center for Public Policy will be engaged to ensure that research findings are appropriately communicated to policy makers. The proposed research will provide fundamental knowledge of factors that mediate nanoparticle transport to oocytes, and offer insights on mechanisms that may lead to alterations in fish embryos.