Photoreception and Circadian Regulation of Cuticle Formation in Insects

• Applicant: Professor Dr. Jan-Henning Dirks
• Subject Area: Animal Physiology and Biochemistry ; Systematics and Morphology (Zoology)
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 581918994

The exoskeleton of insects consists of the cuticle, a complex biological composite material that fulfils multiple structural and physiological functions. The exceptional properties of the cuticle arise from the hierarchical organisation of chitin fibres and proteins arranged in fine layers. In the exoskeletons of many insect species, regularly alternating layers can be observed that result from time-of-day-dependent differences in cuticle deposition. Previous studies on locusts have shown that this process is controlled by a circadian clock, which in turn responds to light stimuli. Remarkably, the photoreceptive sensor responsible for this regulation is located within the epidermis itself. The proposed research project will, for the first time, systematically investigate how widespread this circadian-controlled and locally light-sensitive cuticle deposition is among insects and which molecular mechanisms underlie this system. The study addresses three central questions: 1. Is the light-induced alignment of chitin fibres a universal feature of insects or a derived trait of specific taxa? 2. How does the circadian control of cuticle formation differ among insect groups, and to what extent do they respond to different light intensities and spectral ranges? 3. Which molecular pathways and photoreceptive proteins in the epidermis of locusts are involved in local light perception and circadian regulation of cuticle synthesis? To answer these questions, selected insect species will be reared under defined light and temperature conditions. The microscopic organisation and periodic layering of the cuticle will be analysed using polarised-light and electron microscopy. Complementary molecular analyses (RT-qPCR) will quantify the light- and time-dependent expression of genes involved in circadian regulation and photoreception. By combining comparative morphology, physiology, and molecular biology, the project will establish a new foundation for understanding how light perception, circadian timing, and biomaterial formation are functionally linked within the insect exoskeleton. The results will provide fundamental insights into the evolution of peripheral circadian systems and illuminate the physiological principles of cuticle formation as an example of adaptive, light-controlled biomaterial synthesis.

• DFG Programme: Research Grants