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Description
Endocrine disruptors (ED) include plasticizers, pesticides, detergents and pharmaceuticals. Many of these chemicals enter rivers and the ocean, where they directly interact with fish and disrupt endocrine responses. Humans are exposed to these chemicals from drinking water and consumption of fish. Endocrine disruptors interfere with a variety of hormone-regulated physiological pathways and have complex effects on human and fish physiology due to the diversity of the hormone receptors and enzymes that they bind. The detailed mechanisms by which ED compounds act is not completely understood, but many are known to bind to nuclear receptors, such as the estrogen receptor (ER), retinoid X receptor (RXR) and peroxisome proliferator-activated receptors (PPARs). Binding of endocrine disruptors to these and other receptors, as well as key steroidogenic enzymes, can disrupt normal physiological processes. Health effects attributed to endocrine disrupting compounds include reproductive dysfunction (e.g., reduced fertility, male and female reproductive tract abnormalities, skewed male/female sex ratios in fish, and altered hormone levels); early puberty; brain and behavior problems; impaired immune function; various cancers and obesity. Recent studies highlight that nanotechnology may have an adverse outcome on the environment and biological systems by interfering with key developmental and endocrine processes. Although nanotechnology byproducts have not been reported as EDs, their effect on development requires study. In my thesis proposal, I will use various molecular methods to identify biomarkers for several nanoparticles (NPs), including sliver, aluminum and silica. The goal of this research proposal is to obtain a more complete understanding of the targets and responses in embryos and adults that are modulated by these NPs and investigate if they serve as EDs. To accomplish this goal, I will uncover novel mRNA biomarkers as precise molecular fingerprints for these NPs using two Massively Parallel Signature Sequencing (MPSS). I propose to use zebrafish for NP biomarker discovery during embryonic development and in adult tissues because the genome sequence is complete. The homology of the zebrafish genome to the human genome allows us to use it as a proxy for human health. Transcriptome data sets using next generation sequencing from zebrafish exposed to NPs have been generated by the Hardiman laboratory at UCSD. RNA-seq profiling (using MPSS) will be carried out with embryonic RNA and liver extracted from zebrafish adult males. These data sets will (1) provide precise genomic signatures for each NP and (2) elucidate the mechanism of interference of these NPs during embryonic development and in adult fish.
