Epidermal cell surface structure and chitin-protein co-assembly determine fiber architecture in the Locust cuticle

Abstract

<jats:title>Summary</jats:title><jats:p>The geometrical similarity of helicoidal fiber arrangement in many biological fibrous extracellular matrices, such as bone, plant cell wall or arthropod cuticle, to that of cholesteric liquid mesophases has led to the hypothesis that they may form passively through a mesophase precursor rather than by direct cellular control. In search of direct evidence to support or refute this hypothesis, here, we studied the process of cuticle formation in the tibia of the migratory locust, <jats:italic>Locusta migratoria</jats:italic>, where daily growth layers arise by the deposition of fiber arrangements alternating between unidirectional and helicoidal structures. Using FIB/SEM volume imaging and scanning X-ray scattering, we show that the epidermal cells determine an initial fiber orientation from which the final architecture emerges by the self-organized co-assembly of chitin and proteins. Fiber orientation in the locust cuticle is therefore determined by both active and passive processes.</jats:p>

Gradients of orientation, composition and hydration of proteins for efficient light collection by the cornea of the horseshoe crab

“…2B). We detected an elevated Br signal in the epicuticle, as previously observed in insects ( 18 ), but not in the outer cornea. Br was also present in the cones but not in the intercone region (Fig.…”

“…The occurrence of these peaks is indicative of cross-beta structures in proteins ( 16 , 17 ). Cross-beta protein organization is common in arthropod cuticles ( 18 , 19 ), however it is often difficult to discriminate the protein reflections from those of chitin as they typically coincide and since chitin-poor or protein-rich layers are usually thin with respect to the probed volume. In L. polyphemus an especially thick epicuticle (the part of the cuticle that is devoid of chitin) allows direct insight into the dominant protein structure in the cuticle.…”

A Spatiotemporal Reconstruction of the C. elegans Pharyngeal Cuticle Reveals a Structure Rich in Phase-Separating Proteins

“…The incorporation of chitin and chitosan within Ecdysozoan cuticles is firmly established ( 75, 76 ). Mounting evidence also indicates that the arthropod cuticle has abundant IDR-rich proteins ( 65 ) with amyloid-like folds ( 77 ). However, of the 12 families of known arthropod cuticle proteins, only CPAP1 and CPAP3 have recognizable conservation with nematodes ( 54, 76 ).…”

Biological Materials Processing: Time-Tested Tricks for Sustainable Fiber Fabrication

“…292,293 In almost all cases, cellulose and chitin-based tissues are processed into hierarchical structures by direct secretion from living cells. 294,295 However, recent work on mistletoe plants provides an example of an abiotic and extracorporeal fiber formation process that may have important relevance for inspiring sustainable polymer processing methods.…”