Ramji Bhandari, PhD
Assistant Professor, Department of Biology
University of North Carolina Greensboro
Gene environment interactions lead to emergence of a phenotype which can consistently be expressed in subsequent generations if these effects are mediated by germ cells and transmitted vertically via germline transmission (transgenerational). Such environmentally induced transgenerational phenotypic traits have been observed in diverse phyla, from plants to mammals. In some species, the exposure-induced phenotypic traits exhibit unique epigenetic alterations in germline stem cells, sperm, and somatic cells. My research group is investigating how environment induces epigenetic alterations in germ cells and the fate of these epigenetic alterations as the organism grows into adulthood, using medaka fish as animal model. Our results suggest that environmental chemicals, mainly bisphenol A (BPA, plastic component), ethinylestradiol (EE2, birth control pill component), and atrazine (herbicide) induce transgenerational reproductive impairment in fish in the third and 4th generation due to a transient exposure of embryos in the first generation. Somatic cells and germline stem cells are able to remove parentally acquired epigenetic marks during epigenetic reprogramming events that occur in embryos after fertilization or prior to sex determination, respectively. In medaka, we have found that some of the environmentally induced epigenetic alterations in germline stem cells can resist reprogramming events and be passed on to sperm and subsequent generation. Studies to elucidate the role of these stable epigenetic alterations (epimutations) in development of phenotypic traits are under progress. Additionally, our laboratory is trying to develop strategies to minimize environmentally induced epigenetic aberrations by nutritional epigenomic method. Results of our research will provide insights into mechanisms underlying environmentally epigenetic inheritance of phenotypes and emergence of phenotypic traits and help develop management plan for prevention of environmentally induced epigenetic in humans.
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