自上世纪初以来，科学家就已经知道很多生物具有探测环境湿度的能力。实际上，对很多生物来说，这种能力是生存的关键。昆虫身体很小，这使得它们对于湿度的变化尤其敏感，因此昆虫一直是研究这种感觉能力的最好模型。然而，尽管科学家作了很多努力，但这种感觉的细胞和分子机制仍然是一个谜。现在，Liu等人提供了关于这一复杂感觉体系中所涉及的分子机制的一些线索。他们发现，果蝇的3个TRP通道参与湿度的探测：water witch (ww)是探测潮湿空气所需要的，而nanchung (nan)和inactive (iav)是探测干燥空气所需要的。他们还发现，表达这些通道的神经元能够刺激果蝇触角上不同的传感性茸毛。机械传感模块可能是决定果蝇探测其所碰到的环境提示能力的生理基础，而这些环境提示也许又能使环境中水分含量的微小变化能被探测到。
原始出处:
Nature 450, 294-298 (8 November 2007) | doi:10.1038/nature06223; Received 25 June 2007; Accepted 3 September 2007
Drosophila hygrosensation requires the TRP channels water witch and nanchung
Lei Liu1, Yuhong Li1, Runping Wang1,2, Chong Yin3, Qian Dong1,2, Huey Hing3, Changsoo Kim4 & Michael J. Welsh1,2
Departments of Internal Medicine,
Departments of Physiology and Biophysics, Howard Hughes Medical Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA
Department of Cell and Structure Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju 500-757, Korea
Correspondence to: Michael J. Welsh1,2 Correspondence and requests for materials should be addressed to M.J.W. (Email: michael-welsh@uiowa.edu).
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The ability to detect variations in humidity is critical for many animals. Birds, reptiles and insects all show preferences for specific humidities that influence their mating, reproduction and geographic distribution1, 2. Because of their large surface area to volume ratio, insects are particularly sensitive to humidity, and its detection can influence their survival3, 4, 5, 6, 7. Two types of hygroreceptors exist in insects: one responds to an increase (moist receptor) and the other to a reduction (dry receptor) in humidity4, 6, 8. Although previous data indicated that mechanosensation might contribute to hygrosensation6, 9, the cellular basis of hygrosensation and the genes involved in detecting humidity remain unknown. To understand better the molecular bases of humidity sensing, we investigated several genes encoding channels associated with mechanosensation, thermosensing or water transport. Here we identify two Drosophila melanogaster transient receptor potential channels needed for sensing humidity: CG31284, named by us water witch (wtrw), which is required to detect moist air, and nanchung (nan), which is involved in detecting dry air. Neurons associated with specialized sensory hairs in the third segment of the antenna express these channels, and neurons expressing wtrw and nan project to central nervous system regions associated with mechanosensation. Construction of the hygrosensing system with opposing receptors may allow an organism to very sensitively detect changes in environmental humidity.
