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Read e-book online Chitin PDF

By Riccardo A. A. Muzzarelli (Auth.)

ISBN-10: 0080203671

ISBN-13: 9780080203676

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Very little pigment can be recovered from chitinous material from Crustacea by exposure to the usual carotenoid solvents and/or protein denaturants, unless the shells have been decalcified. However, aqueous citric acid, disodium salt of ethylenediaminetetraacetic acid and hydrochloric acid dissolve calcium carbonate but leave all pigments firmly associated with the tough and pliable chitinous pieces; carotenoids, then, are not bound to the calcareous part. It has also been discounted that carotenoids are bound to the scleroproteins as occurs for instance in some feathers.

Arthropodins are soluble in water at high temperature; a suitable solvent for their extraction has been proposed by Trim (1941) and their analyses have been performed by many authors (Jeuniaux, 1971). Sclerotins are water-insoluble. Enzymic studies and acidic hydrolysis of cuticles have also led to the conclusion that a stable linkage exists, proteins being linked to chitin through a non-aromatic aminoacid (Lipke & Geoghegan, 1971; Lipke, Grainger & Siakotos, 1965). Fragments of mucoprotein with glycosyl, N-acetylglucosaminyl and peptidyl residues were isolated.

In fact, as the cuticle becomes more sclerotized, it becomes more lipophilic (Fraenkel & Rudall, 1940). The cuticle would then hold lipid soluble compounds. The high lipid content observed in some resistant insects, but not in others, 38 Chitin would depend on the availability of lipids for deposition in the cuticle and would be a manifestation of sclerotization. The lipid further increases the insecticide-holding power of the cuticle. Bradleigh & Law (1971) demonstrated that the cuticular composition of Heliotis virescens larvae differs according to the degree of penetration of DDT in the cuticle.

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Chitin by Riccardo A. A. Muzzarelli (Auth.)


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