Pyrexia is a new thermal transient receptor potential channel endowing tolerance to high temperatures in Drosophila melanogaster

Several transient receptor potential channels were recently found to be activated by temperature stimuli in vitro 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14. Their physiological and behavioral roles are largely unknown. From a temperature-preference behavior screen of 27,000 Drosophila melanogaster P-insertion mutants, we isolated a gene, named pyrexia (pyx), encoding a new transient receptor potential channel. Pyx was opened by temperatures above 40 °C in Xenopus laevis oocytes and HEK293T cells. It was ubiquitously expressed along the dendrites of a subset of peripheral nervous system neurons and was more permeable to K+ than to Na+. Although some pyx alleles resulted in abnormal temperature preferences, pyx null flies did not have significantly different temperature preferences than wild-type flies. But 60% of pyx null flies were paralyzed within 3 min of exposure to 40 °C, whereas only 9% of wild-type flies were paralyzed by the same stimulus. From these findings, we propose that the primary in vivo role of Pyx is to protect flies from high-temperature stress.