Drosophila hygrosensation requires the TRP channels water witch and nanchung

Wet and dry Since the early years of the last century, it has been known that many organisms possess the ability to detect ambient humidity. For some organisms, this ability is crucial for survival. Because their small body size makes them particularly susceptible to changes in moisture, insects are an ideal model for investigating this sense. Yet, despite much effort, the cellular and molecular mechanisms responsible have remained a mystery. Now, Liu et al. have discovered two Drosophila transient receptor potential channels involved in sensing humidity: water witch (wtrw) is required to detect moist air, while nanchung (nan) is required to detect dry air. Neurons expressing these channels innervate distinct sensory hairs in the fly antenna. Mechanosensation may be the sensory modality that underlies the ability to detect opposing environmental cues, while these opposing cues might allow minute changes in moisture content of the environment to be detected.