THE STRUCTURE OF INSECT CUTICLES
THE STRUCTURE OF INSECT CUTICLES
复制标题
DOI：
10.1098/rspb.1947.0006
复制
发表时间：
1947-01-01
期刊：
影响因子：
--
通讯作者：
RUDALL, KM
中科院分区：
文献类型：
--
作者：
FRAENKEL, G;RUDALL, KM
The dried mature larval cuticle of Sarcophaga falculata contains 50.3% chitin, 45.7% protein and 4% residue, corresponding to successive longitudinal monolayers of beta-protein and chitin in the approximate ratio of 3 amino acid residues to 1 chitobiose, a fact which is confirmed by X-ray diffraction studies. On conversion of the cuticle to puparium, dry weight increases 6.3% without corresponding increase in the absolute amount of protein and chitin, accounted for by incorporation in the cuticle of phenolic substances derived from free tyrosine in the blood. Free tyro-sine rises from 0.37% to 0.71% in the larva in the last 48 hrs. before pupation, and falls dramatically to 0.085% in the 30 hr. old pupa. The water soluble cuticular protein, arthro-podin is soluble in hot water and hot, but not cold, 10% tri-chloroacetic acid, and may be precipitated cold by alcohol 45% and stronger. The pigment-protein complex in puparia is soluble in 5% hydrochloric acid or potassium hydroxide and reprecipitated as a dark brown precipitate on neutralization. Its nitrogen content of 8.6% indicates about equal portions of protein and non-nitrogenous phenolic substances. The amount of pigment in the puparium, 5.6% corresponds to the gain of weight in conversion of cuticle to puparium. The cuticle may be artificially hardened and darkened by benzoquinone, catechol and hydroquinone. Melanin is precipitated in unheated cuticles treated with tyrosine or "dopa", but tanning and darkening is more specific with catechol. When mature larvae are immersed in methanol, cuticular darkening and hardening takes place in 4 days in a manner closely analogous to pupatibn. Darkening occurs equally anterior and posterior to a ligature behind the ganglion, so that hormonal effects are eliminated. Methanol probably inhibits the dehydrogenase of blood which normally inhibits the tyrosinase in larvae. Comparative results are presented in less detail on Phormia terranovae, Sphinx ligustri, Bombyx mori, Tenebrio molitor, Dytiscus, Locusta migratoria, Dixippus morusus, Buthus quinquestriatus, Ephestia kuehniella, Gal-leria melonella, and on ventral intersegmental cuticle of lobster.
