Temperature sensing is critical for survival: animals must avoid conditions that would freeze or burn them and choose the best conditions for growth and reproduction. To achieve these goals, animals possess highly sensitive temperature sensors. However, the mechanisms by which these sensors operate at the molecular level are largely unknown. Furthermore, it is unknown whether differences in these sensors contribute to the adaptation of different animals to different environments. This research project,entitled "The molecular basis of thermal preference variation in Drosophila", addresses these basic questions by combining molecular, genetic and physiological approaches to study the thermal sensors of Drosophila fruit flies from different climates, ranging from temperate regions to the Mojave Desert. By comparing the molecular properties of thermal sensors from different fruit fly populations and examining how these properties affect behavioral responses to temperature, this study will provide fundamental insights into how thermal sensors respond to temperature at the molecular level and how these sensors contribute to variations in animal behavior. As closely related thermal sensors are found in vertebrates as well as in other invertebrate species, results from these studies will have direct implications for thermal sensing and behavior across a wide range of animals. In addition to the scientific impact, this project also incorporates an experiential learning opportunity for undergraduates, directly engaging students in scientific research examining natural variation in temperature sensing among Drosophila populations.
Temperature has dramatic effects on animal physiology, and animals use multiple strategies to respond to temperature and maintain acceptable body temperatures. However, precisely how animals perform these essential functions is not well understood. In terms of intellectual merit, this research project studied how relatively simple model organisms, fruit flies, sense and respond to variations in temperature. The approach was to study the temperature responses of multiple fruit fly species, including the widely used genetic model system Drosophila melanogaster. Among the outcomes of this work was the examination of temperature responses among many species. This work contributed to the discovery of a way in which these animals can control the activity of their temperature sensors by making multiple variations of the temperature sensing molecule using a process called alternative transcriptional initiation, a process all animals use to regulate expression of genes. This work also provided a new dimension to our understanding of the molecular basis of inter-species differences in thermal preference, and led to the discovery of a new class of temperature sensing molecule, a molecule which surprisingly resembled molecules usually used taste signaling. This suggests a potentially close relationship between these sensory modalities. In terms of broader impact, this project incorporated undergraduate education in the form of a laboratory course, "Project Laboratory in Neurobiology and Behavior", created in the Biology Department at Brandeis University. This course provided students with an experiential learning opportunity in which they engaged in scientific research by characterizing the temperature sensing behavior of various fly species. This allowed students to perform original research and gain experience in how to analyze and present data. To date, two research papers have been published that involve work supported by this grant: 1. K. Kang, V.C. Panzano, E.C. Chang, L. Ni, A.M. Dainis, A.M. Jenkins, K. Regna, M.A.T. Muskavitch and P.A. Garrity. (2012) Modulation of TRPA1 thermal sensitivity enables sensory discrimination in Drosophila. Nature, 481: 76-80. PMC3272886 2. L. Ni, P. Bronk, E.C. Chang, A.M. Lowell, V.C. Panzano, J.O. Flam, D.L. Theobald, L.C. Griffith, and P.A. Garrity. (2013) A gustatory receptor paralogue controls rapid warmth avoidance in Drosophila. Nature, 500, 580-584.
