Chitin metabolism in insects: structure, function and regulation of chitin synthases and chitinases

Abstract

SUMMARY Chitin is one of the most important biopolymers in nature. It is mainly produced by fungi, arthropods and nematodes. In insects, it functions as scaffold material, supporting the cuticles of the epidermis and trachea as well as the peritrophic matrices lining the gut epithelium. Insect growth and morphogenesis are strictly dependent on the capability to remodel chitin-containing structures. For this purpose, insects repeatedly produce chitin synthases and chitinolytic enzymes in different tissues. Coordination of chitin synthesis and its degradation requires strict control of the participating enzymes during development. In this review, we will summarize recent advances in understanding chitin synthesis and its degradation in insects.

Gene Expression Profiling in Daphnia magna Part I: Concentration-Dependent Profiles Provide Support for the No Observed Transcriptional Effect Level

“…The ability of daphnids to reproduce is directly related to their molting activity. Molting is a highly coordinated process regulated by arthropod hormones and requires Chitinase activity and the synthesis of new cuticle proteins (21). Several chitinases and cuticle proteins were downregulated by Cu and Zn at high concentrations (see Table S3 in the Supporting Information).…”

Cloning and sequence analysis of chitin synthase gene fragments of Demodex mites

“…During ecdysis, the nascent and non-sclerotized epidermis is covered by the old one, and is gradually expanding when the old one is molting. Therefore, the insects synthesize and degrade chitin endlessly, with some regularity, to ensure the molting completion and PM regeneration (Merzendorfer and Zimoch, 2003).…”

Retroactive, a membrane‐anchored extracellular protein related to vertebrate snake neurotoxin‐like proteins, is required for cuticle organization in the larva of Drosophila melanogaster

“…The knk gene encodes an unknown protein, and the kkv gene codes for the Chitin Synthase-1 (CS-1/Kkv) that produces all chitin in the epidermis, including the head skeleton and the tracheae (Ostrowski et al, 2002;Merzendorfer and Zimoch, 2003). To test for the presence of chitin in rtv larvae in comparison to wild-type larvae, we performed a histochemical analysis to visualize chitin using Fluostain (Fig.…”

“…The stability of the cuticle arises from anti-parallel packing of the chitin fibers (␣-chitin). These fibers form microfibrils aligned in horizontal layers (laminae) that are often rotated with respect to each other (Bouligand, 1965;Neville, 1975;Merzendorfer and Zimoch, 2003). Additional hardening of the cuticle involves crosslinking of proteins and chitin with catecholamines and phenols, a process called sclerotization (Wright, 1987;Sugumaran, 1998).…”