We are interested in the biology of a small, evolutionarily related group of fungi that cause disease in healthy humans. These environmental fungi are exquisitely responsive to mammalian body temperature, which triggers drastic changes in cell shape and the induction of virulence properties. We dissect temperature-dependent signaling in these thermally dimorphic fungal pathogens to reveal fundamental molecular paradigms with broad significance to our understanding of cellular circuits. Specifically, we study the circuitry used to establish and maintain thermosensation in Histoplasma and Coccidioides species and elucidate how temperature-induced fungal effectors manipulate the biology of innate immune cells. Ultimately we hope fundamental discoveries can be applied to a variety of biological contexts, including generating synthetic temperature-response circuits and harnessing fungal effectors as immunomodulatory agents during disease.