| Popis: |
The objective of this investigation was to demonstrate that “cuticulin” (the hard amber material of the insect cuticle) is a compost of sclerotin (quinone-tanned protein) with lipid, furnished by the oenocytes. The tubular system of the cuticle consists of a set of tubular filaments discharging polyphenols (sclerotin precursors) and a set of tubular filaments discharging lipids. These two secretions accumulate and combine in those sites where cuticulin is formed. It is suggested that the combination of sclerotin and lipid, which takes place at the molecular level during their secretion is due simply to hydrophobic interaction; and that the increase in water loss induced by lipid solvents, by detergents, and by heating to a critical temperature, results from the severing of this physical link. There are three sites for cuticulin deposition: (1) the thin waterproofing layer on the outer surface of the primary membrane or “outer epicuticle”, (2) in the substance of the amber-coloured inner epicuticle, (3) in the hard amber exocuticle. Cuticulin affords the insect both the hardness and strength of sclerotin and the waterproofing properties of wax. |
