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Molecular basis of infrared detection by snakes

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Abstract

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.

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Figure 1: Anatomy of the pit organ and comparison of gene expression in snake sensory ganglia.
Figure 2: Expression of TRPA1 and TRPV1 in rattlesnake sensory ganglia.
Figure 3: Functional analysis of snake TRPA1 channels.
Figure 4: Analysis of TRPA1 from python and boa.
Figure 5: Functional analysis of snake sensory neurons.

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Accession codes

Primary accessions

Gene Expression Omnibus

Data deposits

Deep sequencing data are archived under GEO accession number GSE19911. GenBank accession numbers are GU562965 (Python regius TRPA1), GU562966 (Elaphe obsoleta lindheimeri TRPA1), GU562967 (Crotalus atrox TRPA1), GU562968 (Crotalus atrox TRPV1), and GU562969 (Corallus hortulanus TRPA1).

Change history

  • 15 April 2010

    A correction was made to the spelling of an author name (N.T.I.) on 15 April.

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Acknowledgements

We thank A. Priel for advice and assistance with calcium imaging and electrophysiology, C. Chu for help with sequencing, J. Poblete for technical assistance, and the staff of the Natural Toxins Research Center serpentarium for animal husbandry. We thank P. Garrity for providing the dTrpA1 cDNA. This work was supported by a Ruth L. Kirschstein National Research Service Award (GM080853) (N.T.I.), a NIH Institutional Research Service Award in Molecular and Cellular Basis of Cardiovascular Disease (A.T.C.), the Howard Hughes Medical Institute (J.S.W.), and grants from the National Institutes of Health, including NCRR Viper grant P40 RR018300-06 (E.E.S. and J.C.P.), P01 AG010770 (J.S.W.) and NS047723 and NS055299 (D.J.).

Author Contributions E.O.G., J.F.C.-M. and N.T.I. designed and performed experiments and analysed data. N.T.I. and J.S.W. developed analytical tools and analysed data. Y.M.K., G.H. and A.T.C. performed experiments and/or provided reagents and analysed data. E.E.S. and J.C.P. supervised snake husbandry and handling. E.O.G., Y.M.K., J.F.C.-M. and D.J. wrote the manuscript with discussion and contributions from all authors. J.S.W. and D.J. provided advice and guidance throughout. D.J. initiated and supervised the project.

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Correspondence to David Julius.

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Gracheva, E., Ingolia, N., Kelly, Y. et al. Molecular basis of infrared detection by snakes. Nature 464, 1006–1011 (2010). https://doi.org/10.1038/nature08943

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