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Nascone-Yoder, Nanette, PhD
Assistant Professor
Ecological Developmental Biology and Ecotoxicology
It is becoming increasingly appreciated that the environment can markedly influence the ultimate manifestation of genotype, and expose a surprising degree of phenotypic plasticity in embryos of the same species, even to the extreme of generating alternative “morphs” within a single population. One of the best studied examples of this environmentally-induced polyphenism occurs in several species of tadpoles, which develop morphs with very distinct craniofacial, tail and gut morphologies, depending on as yet undefined cues originating from predators, conspecifics, and/or diet, among other factors. Since such polyphenism may be mediated by semiochemical or endocrinological cues, we are employing the tools and principles of chemical genetics to identify molecules that can induce phenotypic transformations in the developing guts of aquatic embryos. For example, in collaboration with David Pfennig (UNC-CH), an expert in the evolution and development of alternative phenotypes in tadpoles of the genus Spea, we plan to identify the hormonal cues and gut-specific gene expression patterns that underlie the development of a carnivorous morph in otherwise omnivorous Spadefoot toad larvae.
The general role that environmental chemical cues, such as natural products or anthropogenic toxins, may play in the development of the gut in other species is unknown. In collaboration with Alex Deiters, we are using chemical genetics to ask questions about the role of natural product-like compounds in the normal and abnormal development of the gut in embryos of the aquatic vertebrates, Xenopus laevis (the African claw-toed frog) and Danio rerio (the zebrafish). In the context of the unexplained high frequency of intestinal malrotation in the human population, such strategies may provide much needed insight into the role of the environment in the etiology of gut-specific birth defects.