A thermal receptor for nonvisual sunlight detection in myriapods

Area of Science:

• Sensory Biology
• Animal Physiology
• Molecular Mechanisms

Background:

• Many organisms, including animals lacking vision, exhibit sunlight avoidance behavior.
• The mechanism for nonvisual light detection, particularly via photothermal conversion, remains experimentally unverified.

Purpose of the Study:

• To elucidate a nonvisual, extraocular sunlight detection mechanism in centipedes.
• To identify the molecular and physiological basis of this sensory pathway.

Main Methods:

• Identification and characterization of the broad-range thermal receptor 1 (BRTNaC1) ion channel in centipede antennae.
• Analysis of BRTNaC1's heat activation, pH dependence, and response to sunlight exposure.
• Investigation of testosterone's effect on BRTNaC1 activity and behavior.

Main Results:

• Discovered BRTNaC1, a heat-activated cation channel (33–48°C) in centipede antennae, structurally related to epithelial sodium channels.
• Demonstrated that sunlight exposure induces a photothermal effect on antennae, activating BRTNaC1.
• Showed that acidic body fluid (pH 6.1) enhances BRTNaC1's thermal sensitivity via protonation.
• Found that testosterone inhibits BRTNaC1 activation and sunlight avoidance behavior.

Conclusions:

• Centipedes possess a sophisticated nonvisual sunlight detection system mediated by BRTNaC1 in their antennae.
• This mechanism involves photothermal conversion, pH-dependent ion channel gating, and hormonal modulation.
• The findings offer insights into diverse sensory strategies in myriapods.