Transplanted leg imaginal discs establish nerve connections with the appropriate neuromeres of the host's thoracic ganglion in the flySarcophaga bullata

Summary Ectopic transplantations of prothoracic leg imaginal discs of mature 3rd instar larvae ofSarcophaga bullata on to young prepupae resulted in the development of supernumerary legs. The nerves that connected these legs with the host's CNS projected in the appropriate neuromere of the thoracico-abdominal ganglion.Supported by the Natural Sciences and Engineering Research Council of Canada.     

Taste responsiveness of the transplanted supernumerary leg in the fleshflySarcophaga bullata

Summary Ectopic legs were produced on the abdomen of the fleshflySarcophaga bullata by transplantation of prothoracic leg imaginal discs. Stimulation of the tarsal chemoreceptors of these ectopic legs with sucrose solution resulted in the extension of the host proboscis indicating the functional connectivity of the sensory axons.Supported by a grant from the Natural Sciences and Engineering Research Council of Canada.I appreciate the technical assistance of John Geibel, Paul Nitishin and Roger Smith.     

Postmolt cuticle growth in a cockroach: in vitro deposition of multilamellate and circadian-like layered endocuticle

Summary Pieces of the hind legs of freshly moltedBlaberus craniifer adults were cultivated in vitro. The deposition of multilamellate and circadian-like layered endocuticle was observed. In multilamellate cuticle, the number of double lamellae was frequently much greater than the number of days in culture. In circadian-like layered cuticle, the number of double layers corresponded to the numbers of days in culture, or it was smaller.I am indebted to Mrs Hassenrück, for excellent assistance. — Supported by the Deutsche Forschungsgemeinschaft (We 389/12-2).     

The postpharyngeal glands and the cuticle of Formicidae contain the same characteristic hydrocarbons

Summary Comparison of the contents of the postpharyngeal gland and cuticular hydrocarbons of five species of ant have shown them to contain the same compounds and to be characteristic of the species. For four species (Formica selysi, Camponotus lateralis, Camponotus vagus andManica rubida), quantitative similarity was very close, but more divergent in the fifth (Myrmica rubra). Glands and cuticle ofM. rubra queens were shown to be closely similar to those of workers, except the glands of queens are larger, but the cuticle of larvae was different from that of adult cuticle and postpharyngeal glands.     

Molecular and Cellular Basis of Regeneration and Tissue Repair

Nymphs of hemimetabolous insects such as cockroaches and crickets exhibit a remarkable capacity for regenerating complex structures from damaged legs. Until recent years, however, approaches to elucidate the molecular mechanisms underlying the leg regeneration process have been lacking. Taking the cricket Gryllus bimaculatus as a model, we found that a phenotype related to regeneration frequently appears during leg regeneration, even though no phenotype is induced by RNA interference (RNAi) in the cricket nymph, designated as regeneration-dependent RNAi. Since then, we have investigated the functions of various genes encoding signaling factors and cellular adhesion proteins like Fat and Dachsous during leg regeneration. In this review, we summarize the classical knowledge about insect leg regeneration and introduce recent advances concerning the signaling cascades required for regenerating a leg. Our results provide clues to the mechanisms of regeneration which are relevant to vertebrate systems.     

Resilin in the cuticle of physogastric queen termites

Summary Resilin is present in the endocuticle of the flexible abdominal intersegmental cuticle of the, physogastric queen of the termite,Odontotermes obesus (Rambur). Resilin seems to assist in the extension of abdomen of the queen termites during physogastry.Acknowledgments. I am grateful to Dr S. O. Anderson for examining the cuticle in the fluorescent microscope. I thank Prof. R. G. Michael for interest in this work, Prof. P. S. Ramakrishnan for providing UV Lamp (Toshnival) for the examination of chromatograms and Mr Sudip Dey for valuable discussions.Previously called A. Sannasi.     

Sclerotization and coloration of the insect cuticle

Summary Evidence indicating linkage between the processes of cuticle hardening and coloration are reviewed. Data and observations for the mutants black and ebony inDrosophila melanogaster are used to construct a possible model for the relationship between these developmental events.     

Chitin in the epidermal cuticle of a vertebrate (Paralipophrys trigloides,Blenniidae, Teleostei)

Lectin binding, endo-chitinase binding and enzymatic degradation studies show that the epidermal cuticle of the bony fishParalipophrys trigloides (Blenniidae) is chitinous. This is the first evidence that a vertebrate species possesses a chitinous tissue. Recently aXenopus gene has been identified which has significant sequence similarity to the catalytic domain of yeast chitin synthase III, a chitin producing enzyme^1,2. Taken together these two findings imply that chitin synthesis capability may be a basic vertebrate feature.     

Caenorhabditis elegans dpy-5 is a cuticle procollagen processed by a proprotein convertase

Genetic analysis of the nematode Caenorhabditis elegans reveals that all dpy-5 alleles are dominant suppressors of bli-4 blistering. Molecular cloning of dpy-5 establishes that it encodes a cuticle procollagen, defects in which are responsible for the short-body, dumpy phenotype. The null mutation, e907 removes the entire coding region, whereas the dpy-5 reference allele, e61, contains a nonsense substitution. RT-PCR analysis and a dpy-5::gfp fusion show that dpy-5 is expressed only in hypodermal cells at all post-embryonic life-cycle stages. Variable expression of dpy-5 in V lineage-derived seam cells suggests an alternative regulatory mechanism in these cells. The dpy-5 gene product contains an Arg-X-X-Arg cleavage motif that could be recognized by a proprotein convertase, such as BLI-4. Mutation of this site cause a dominant dumpy phenotype suggesting Dpy-5 procollagen requires processing for normal cuticle production. Received 13 January 2006; accepted 23 March 2006     

Haemolymph ecdysteroids level following the injection of ecdysone or ecdysterone; its relation with tegument and midgut response inAeshna cyanea (Insecta,Odonata)

Summary The haemolymph ecdysteroid level after injection of ecdysone or ecdysterone inAeshna cyanea larvae has been determined by a radioimmunoassay method. The rate of excretion appears to be dependent on both the ecdysteroid injected and the time of injection. In case of ecdysone injection, the secretion of the epidermis cuticle and the differentiation of the imaginal midgut epithelium occur when the ecdysteroid level remains low for many days.     

A somatotopic organization of leg afferents in the spiderCupiennius salei Keys. (Araneae,Ctenidae)

Summary Axonal anterograde degeneration after ablation of different leg segments of the spiderCupiennius salei was traced using LM-and EM-methods. The pattern of degeneration seen in cross sections of the leg nerves close to their entry into the subesophageal ganglion shows a somatotopic organization of afferents within the leg nerves coming from different leg segments. All afferents run through the ventral part of the nerve.Acknowledgment. We thank Dr E.A. Seyfarth for helpful discussions. Parts of the study were supported by the Deutsche Forschungsgemeinschaft (W.G., SFB45/A1).     

Induction of autotomy in the American bird grasshopperSchistocerca americana (Drury) by the ecdysone agonist RH-5849 and investigation of its mode of action

The non-steroidal ecdysone agonist RH-5849 (1,2-dibenzoyl-l-tert-butylhydrazine) was found to be an effective neurotoxicant on injection into the American bird grasshopper,Schistocerca americana (Drury). Treated grasshoppers became immediately hyperactive, followed by loss of coordination, paralysis and eventually death. We also discovered that this compound induced bilateral autotomy of the metathoracic legs during the early stages of intoxication. However, no evidence of ecdysonergic or morphogenetic activities was observed. Synergism studies with neurotoxins of known mode of action suggested that RH-5849 has a mechanism of action similar to that of 4-amino pyridine, which blocks potassium channels.     

Biological activity of flucycloxuron,a novel benzoylphenylurea derivative,onTenebrio molitor: comparison with diflubenzuron and triflumuron

Flucycloxuron, a novel benzoylphenylurea (BPU) derivative, exhibited insecticidal activity when injected into newly ecdysed pupae ofTenebrio molitor. Mortality occurs because of defective adult ecdysis. Treatment caused a reduction in both cuticle thickness and incorporation of¹⁴C-labelled precursor into chitin, although it had no significant effect on the protein synthesis. The potencies of other BPU compounds as inhibitors of chitin biosynthesis have been examined and results showed that diflubenzuron was less effective than either flucycloxuron or triflumuron.     

Excretion of acid hydrolases during molting inPhilosamia ricini

Summary The level of the acid hydrolases -glucuronidase (EC 3.2.3.11), acid phosphatase (EC 3.1.3.2) and acid protease (EC 3.4.4) was studied during larval growth and molting inP. ricini. The level of activity of these enzymes remained low during larval growth; however, the level increased sharply at the time of molting and declined sharply thereafter in the newly ecdysed insect. Interestingly, the diminished activity of these enzymes was almost quantitatively recovered in the cast-off cuticle. The excretion of acid hydrolases through the cast-off cuticle has hitherto not been reported in insects during molting.     

Changes in the free amino acid pattern of haemolymph of the common indian scorpionPalamnaeus bengalensis during moulting

Summary Haemolymph ofPalamnaeus bengalensis contains normally 12 and during moulting up to 15 free amino acids, being in maximal number at the end of ecdysis. Aminoacidaemia is most pronounced during the pharate stage. Tyrosine appeared for tanning of the cuticle. Taurine and methionine were not present.Acknowledgment. The author is thankful to Dr.S. C. Shrivastava for valuable guidance and State C.S.I.R. (U.P.) for funds.     

Site attachment of a protelean parasite (Erythraeidae:Leptus sp.)

Summary Leptus sp. showed no site preference when they attached to an insect host. After the chelicera penetrated the host's cuticle a substance was secreted to cement the mite to its host.     

Synchronization of deposition of daily growth layers in the cuticle of the cockroachBlaberus fuscus by gating of moult

Summary InBlaberus fuscus, combined light/dark-warm/cold cycles induce a rhythm of moulting. Most of the moults take place in the middle of the dark cold phases. Because of a stable phase-relation between moulting time and endocuticle growth rhythm, the latter is synchronized with the environmental cycles, too; lamellated layers are deposited during the light warm phases, which correspond to the time of resting of the cockroaches. Therefore, the cuticle growth is internally synchronized with rhythmic locomotory activity and metabolic rhythms.     

Quinone tanning in Agnatha

Summary The buccal teeth and notochordal sheath of the marine hagfish,Petromyzon marinus (L.) are phenolically tanned like the cuticle of insects and other arthropods.Acknowledgments. We are grateful to Dr Bill Lovejoy for generously supplyingP. marinus L. A.R.V. is thankful to Prof. R.G. Michael for encouragement.Previously called A. Sannasi.     

Isolation and partial characterization of cuticular collagen from the parasitic nematodeGaigeria pachyscelis

Summary The cuticle from adultGaigeria pachyscelis was isolated by solubilizing the internal tissues with sodium dodecyl sulphate (SDS) at 37°C. Cuticular protein was extracted with guanidine-HCl and -mercaptoethanol and purified by ammonium sulphate fractionation and DEAE-cellulose chromatography. SDS-polyacrylamide gel electrophoresis of purified protein revealed 2 polypeptides with apparent mol. wts of 58,000 and 74,000. As judged from their hydroxyproline content both of them are collagenous in nature. Results of gel filtration indicate that cuticular collagen exists in two forms, a non-associated form at low concentration and an associated form at high concentration.Acknowledgments. We thank Drs L.N. Singh and H.C. Tewari for providing the necessary facilities. Laboratory assistance of Mr Ram Kishore is highly appreciated.     

Initial transdetermination in the first leg discs of differentDrosophila species

Initial transdetermination leads from lateral and medial halves of male first leg imaginal discs almost exclusively to structures of the base and the spread (blade) of the wing. Mesonotum never appeared. The frequency of transdetermination is species-specific and most probably cell-autonomous. Medial halves transdetermine more frequently than lateral halves. Under the influence of an equivalent amount of blastema growthD. nigromelanica transdetermine with a much higher frequency thanD. virilis.