Proximate und ultimate Gründe der Faserorientierung in der Kutikula von Insekten

Overview

Insect cuticle shows the presence of daily growth bands which consist of layers with parallel (deposited at day) and helicoidal (deposited at night) orientated chitin fibres. In our previous DFG-project (281694208), we used this local light sensitivity of locust cuticle to successfully identify several fundamental mechanisms of chitin fibre orientation. Specifically, we showed that while the formation of cuticle with unidirectional fiber architecture is tightly controlled by cells, the formation of helicoidal patterns involves co-assembly of chitin and proteins and occurs away from the cell surface. Also, we found that cuticle thickness does not scale linearly with the number of deposited layers, suggesting progressive compactization. Moreover, we identified the chitin modifying deacetylase LmCDA2 being crucial for chitin fibre orientation. The objective of this follow-up proposal in collaboration with the TU Dresden and the University of Tübingen is two-fold: (1) establish a deeper mechanistic understanding of the cell-regulated and co-assembly processes including the role of microvilli and newly discovered vesicular structures, the physico-chemistry of the co-assembly and the genetic control of the processes. And (2) to identify the “ultimate” reasons for this alternating fiber organization pattern, including a materials-level study of its effect on the cuticle physical properties. At the HSB we will investigate fundamental proximal and ultimate principles of the dermal light sensor. We will grow insects under controlled conditions to investigate the wavelength and intensity response of the cuticular light sensor. We will also perform a comprehensive mechanical analysis to investigate possible biomechanical advantages of the alternating cuticle layers.