Meeting Abstract
Boid and crotaline snakes (boas, pythons and pit vipers) image their worlds simultaneously in two very different regions of the electromagnetic spectrum – visible light, and mid-to-long-wavelength infrared. This fascinatingly novel approach to targeting potential prey and predators and for locating appropriate refugia provides interesting opportunities to understand thermosensation and the evolution of imaging sensors in animals generally. In addition, analysis of this unique and rare sensory system may inform the development of new artificial thermosensors that could someday approach the sensitivity and effectiveness of those utilized by these snakes. Here we report a comprehensive analysis of transient receptor potential (TRP) ion channels as molecular thermosensors in the snake pit organ-based infrared imaging system. Immunofluorescence (including appropriate controls) and laser-scanning confocal microscopy revealed multiple TRP channels – particularly TRPA1 – in terminal nerve masses of snake pit organs in both pythons and pit vipers. Pharmacological manipulation of infrared-based thermal targeting through the use of a TRPA1 antagonist dramatically inhibited the ability of copperheads (Agkistrodon contortrix) to accurately and efficiently target warm objects. Finally, the same TRPA1 antagonist inhibited heat-induced, pit organ-mediated activity in the brain, demonstrated by functional magnetic resonance imaging (fMRI). The latter result provides not only physiological evidence for TRPA1 as the snake pit organ’s molecular thermosensor, but also the first demonstration by real-time neuroimaging of the infrared imaging system’s neural pathway in the snake brain.
