只有四种哺乳动物已知拥有能够探测红外线的“第六感”，它既被用于捕食目的，也被用于热调控目的。
这些动物包括三种有远亲关系的蛇（颊窝毒蛇和两种蟒蛇：英文名称分别为python和boa）及吸血蝙蝠。调控这一感觉的颊窝器官从解剖角度和行为角度都受到了广泛研究，但对红外线探测能力背后的信号传导机制或所涉及的分子人们却知之甚少。
现在，Gracheva等人发现，有颊窝的蛇依赖离子通道TRPA1来精确探测热量。这一发现增加了TRPA1家族蛋白所具有的探测功能，这些蛋白在哺乳动物中探测刺激性化学物质、在昆虫中探测热变化。(生物谷Bioon.com)
生物谷推荐原文出处：
Nature doi:10.1038/nature08943
Molecular basis of infrared detection by snakes
Elena O. Gracheva1,6, Nicholas T. Ingolia2,3,4,6, Yvonne M. Kelly1, Julio F. Cordero-Morales1, Gunther Hollopeter1,7, Alexander T. Chesler1, Elda E. Sánchez5, John C. Perez5, Jonathan S. Weissman2,3,4 & David Julius1,2
Department of Physiology,
Department of Cellular and Molecular Pharmacology,
Howard Hughes Medical Institute,
California Institute for Quantitative Biosciences, University of California, San Francisco, California 94158-2517, USA
Natural Toxins Research Center, Texas A&M University- Kingsville, Texas 78363, USA
These authors contributed equally to this work.
Present address: Department of Biology, University of Utah, 257 South 1400 East, Salt Lake City, Utah 84112-0840, USA.
Snakes possess a unique sensory system for detecting infrared radiation, enabling them to generate a ‘thermal image’ of predators or prey. Infrared signals are initially received by the pit organ, a highly specialized facial structure that is innervated by nerve fibres of the somatosensory system. How this organ detects and transduces infrared signals into nerve impulses is not known. Here we use an unbiased transcriptional profiling approach to identify TRPA1 channels as infrared receptors on sensory nerve fibres that innervate the pit organ. TRPA1 orthologues from pit-bearing snakes (vipers, pythons and boas) are the most heat-sensitive vertebrate ion channels thus far identified, consistent with their role as primary transducers of infrared stimuli. Thus, snakes detect infrared signals through a mechanism involving radiant heating of the pit organ, rather than photochemical transduction. These findings illustrate the broad evolutionary tuning of transient receptor potential (TRP) channels as thermosensors in the vertebrate nervous system.
