Research in my laboratory is focused on identifying factors that regulate or stimulate development of the nervous system in the frog, Xenopus laevis. Our experiments have been directed toward identifying the influence of early patterning genes in eye and olfactory system development and the tissue interactions and hormones that effect the olfactory system during embryonic development and metamorphosis. In one set of experiments, we isolated cDNA clones for the transcription factor, Pax-6, and we are examining the function of this gene in neural development. Other experiments are focused on determining the roles played by Distal-less 5 in the developing olfactory system. To study tissue interactions, we have used olfactory placode removal and olfactory nerve transection. We demontrated that olfactory axons are critical for normal development of their central target, the olfactory bulb, during embryonic development and metamorphosis. In addition, we have shown that the sensory afferents change during metamorphosis, stimulated, at least in part, by thyroid hormone secretion. Prior to metamorphosis, there are two different types of olfactory epithelium. At metamorphosis, a third area of olfactory epithelium develops de novo, and one of the previous areas of epithelium undergoes major cellular transformations. Coincident with the transformations in the periphery are significant changes in the olfactory bulb. We hope to determine whether the patterns of development that occur during metamorphosis resemble those observed during embryonic development, with regard to gene expression and tissue interactions, and whether thyroid hormone is required to stimulate all the changes occurring at metamorphosis.