Pupal cuticle

Ohnishi, E. 1959. Pigment composition in the pupal cuticles of two colour types of the swallowtails, Papilio xuthus L. and P. pmtenor demetrius Cramer. J. Insect Physiol., 3 132-145. 

Stamecker G. (1997). Hormonal control of lutein incorporation into pupal cuticle of the butterfly Inachis io and the pupal melanization reducing factor. Physiol Entomol 22 65-72. 

Dopa is converted by at least some insects into N-P-alanyldopamine, which is a preferred substrate for the o-diphenol oxidase of the insect pupal cuticle. Oxidation of this substrate plays a crucial role in the... 

We have used solid state C-NMR to follow the changes in chemical composition that occur when M. sexta pupal cuticle becomes sclerotized (Table IX). The soft, newly ecdysed pupal cuticle is mostly water (80%) and protein (14%), with minor amounts of chitin, diphenol and lipid (<3%). The sclerotized pupal exuviae contain sixfold less water, twofold more protein and 17-fold more of both chitin and diphenol. Thus, the process of pupal cuticle sclerotization consists of dehydration together with substantial enrichment of chitin, protein and diphenolic compounds. 

Figure 3 Proposed structure for diphenol mediated cross-link between protein and chitin in M. sexta pupal cuticle (from Schaefer et al. 24).

In the search for the paper factor, extracts from several gymnosperms were assayed on P. apterus fifth instars (Table 1) [83, 84, 85]. Extracts of wood and bark of a number of these conifers were also injected into pupae of the wax moth, Galleria mellonella a localized scaleless patch was observed in the pupal cuticle at the site of injection with these extracts. However, no abnormal effects on development were observed [86]. The authors speculated that this absence of activity may be attributable to the dilute concentration of active ingredients in the extracts. 

Laccase. Laccase (EC 1.10.3.2, diphenol O2-oxidoreductase) is a copper-containing phenoloxidase that has been detected in cuticles of at least 16 species of insects, including the pupal cuticle of M. sexta (17,18, Thomas et.al, unpublished data). It is present in the inner epicuticle of L. cuprina (15). This enzyme is present in the active form during sclerotization and it probably generates the o-quinones that participate in cross-linking reactions. A common problem encountered in studies of cuticular laccase is its insolubility. Soluble laccases have been extracted from larval dipteran cuticle, but endogenous proteases are also known to be present in such cuticle. 

Yamazaki (19) was the first to discover laccases in insects. She has recently used sodium dodecyl sulfate to extract laccases from Bombyx mori cuticle. The enz3rmes can be identified by immunoblotting techniques after separation by sodium dodecyl sulfate polyacrylamide gel electrophoresis, but the enzjrmatic activity has not yet been recovered after the detergent treatment (20). The standard protocol involving proteolysis with exogenous trypsin solubilizes laccase from the pupal cuticle of M. sexta Q8). Following incubation of pupal cuticle from M, sexta with... 

Dopa quinone imine conversion factor M,sexta Pharate pupal cuticle 11,63... 

The biological test of the action of the juvenile hormone that is most often used is inhibition of the imaginal ecdysis . Williams o ugg, cecropia pupae and an injection technique Schneiderman et described a test done on the pupal cuticle, which is very sensitive. Wigglesworth has made investigations with a similar technique on various insects and found that only Rhodnius and Tenebrio were suitable. In Tenebrio an injection technique also produced good results. 

If tissue is shiny, then the pupal cuticle has been secreted and antibody staining will be difficult. 

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