Search results for "Arthropod cuticle"

2018

BackgroundThe insect cuticle covers the whole body and all appendages and has bi-directionnal selective permeability: it protects against environmental stress and pathogen infection and also helps to reduce water loss. The adult cuticle is often associated with a superficial layer of fatty acid-derived molecules such as waxes and long chain hydrocarbons that prevent rapid dehydration. The waterproofing properties of cuticular hydrocarbons (CHs) depend on their chain length and desaturation number.DrosophilaCH biosynthesis involves an enzymatic pathway including several elongase and desaturase enzymes.MethodsThe link between desiccation resistance and CH profile remains unclear, so we tested…

The fine structural organization of sternal glands of pseudergates and workers in termites (Isoptera): a comparative survey

2008

1873-5495 (Electronic) Comparative Study Journal Article; Thirty-nine species belonging to different families of termites are studied to give a comprehensive view of the evolution of the sternal glands. Several modifications occurring at cuticular and cytological levels are described in neuter castes. The outer epicuticle is always pierced by epicuticular pores. In advanced termites the epicuticular filaments greatly increase in number and length creating a thick layer. The pore canals gradually enlarge while the cuticle changes into a lattice structure lining an extracellular space in which the secretion is stored. Two classes of cells are present in basal termites (Mastotermitidae, Hodote…

A cluster of cuticle protein genes of Drosophila melanogaster at 65A: sequence, structure and evolution

1997

0016-6731 (Print) Journal Article Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S.; A 36-kb genomic DNA segment of the Drosophila melanogaster genome containing 12 clustered cuticle genes has been mapped and partially sequenced. The cluster maps at 65A 5-6 on the left arm of the third chromosome, in agreement with the previously determined location of a putative cluster encompassing the genes for the third instar larval cuticle proteins LCP5, LCP6 and LCP8. This cluster is the largest cuticle gene cluster discovered to date and shows a number of surprising features that explain in part the genetic complexity of the LCP5, LCP6 and LCP8 loci. The genes encoding LCP5 a…

Histochemical and biochemical investigations concerning the function of larval oenocytes of Tenebrio molitor L. (Coleoptera, Insecta).

1980

Larval oenocytes of Tenebrio molitor were investigated histochemically. In contrast to the lipid droplets of the fat body, they did not stain with Sudan black. A positive reaction for lipoproteins appeared only after destructive oxidation with sodium hypochlorite. These lipoproteins are the remnants of degenerated membranes, as revealed by ultrastructural analysis. Polyphenols could be identified in the exocuticle of exuvia, and in the newly formed procuticle. Endocuticle, epidermis and oenocytes showed no staining reaction. In oenocytes a great amount of lipase is also present which could be detected with several Tweens as substrates. The significance of these lipases remains unclear, sinc…

The regulation of expression of insect cuticle protein genes

2010

International audience; The exoskeleton of insects (cuticle) is an assembly of chitin and cuticle proteins. Its physical properties are determined largely by the proteins it contains, and vary widely with developmental stages and body regions. The genes encoding cuticle proteins are therefore good models to study the molecular mechanisms of signalling by ecdysteroids and juvenile hormones, which regulate molting and metamorphosis in insects. This review summarizes the studies of hormonal regulation of insect cuticle protein genes, and the recent progress in the analysis of the regulatory sequences and transcription factors important for their expression.

Effects of cuticle structure and crystalline wax coverage on the coloration in young and old males of Calopteryx splendens and Calopteryx virgo

2010

Male secondary sexual characters, such as color patterns, are often investigated at the macroscale level. However, micro- and nanoscale levels of morphological investigations may reveal functional features responsible for a particular coloration, thus providing more information, e.g., about the condition dependence of male sexual characters. The aim of this paper was to investigate cuticle color and its structure in males of two congeneric damselfly species, Calopteryx splendens and Calopteryx virgo, and reveal possible color changes with age. According to spectrometer measurements, C. splendens males were bluer and had a greater saturation of blue in their abdomen than C. virgo males, whic…

Ultrastructure and formation of the physogastric termite queen cuticle

1982

0040-8166 (Print) Journal Article; The physogastric termite queen is the most striking example in insects of growth in size without cuticular moulting. This phenomenon has been studied with electron microscopy and histochemical tests in two species of higher termites, Cubitermes fungifaber and Macrotermes bellicosus. The abdominal hypertrophy (physogastry) is allowed by growth of the arthrodial membranes of the swarming imago. The growth is slow (over several years) but important: the cuticular dry weight is multiplied by 20 in C. fungifaber, by 100-150 in M. bellicosus. The termite queen cuticle arises from the transformation of the cuticle of the swarming imago or imaginal cuticle (unfold…

Fine Determination of the Molt Cycle Stages in Orchestia cavimana Heller (Crustacea: Amphipoda)

1986

ABSTRACT The successive stages of the molt cycle of the terrestrial crustacean amphipod Orchestia cavimana are finely described and illustrated in order to give precise reference marks for experimental, physiological, and biochemical studies. The method of determination, very rapid and easy, is based upon the observation of the morphogenesis of the dactylopodite and the propodite from the third pereiopod. The events of the early morphogenesis of the claw from the dactylopodite divide the intermolt period C into four stages. The formation of spines and the secretion of the epicuticle and then the procuticle at the level of the propodite divide the premolt period into seven stages. The entire…

Embryonic integument and "molts" in Manduca sexta (Insecta, Lepidoptera).

2002

In Manduca sexta the germ band is formed 12 h post-oviposition (p.o.) (=10% development completed) and is located above the yolk at the egg surface. The cells show a polar organization. They are engaged in the uptake and degradation of yolk globules, pinched off from the yolk cells. This process can be observed in the integumental cells during the first growth phase of the embryo that lasts until “katatrepsis,” an embryonic movement that takes place at 40% development completed. At 37% development completed, the ectoderm deposits a thin membrane at its apical surface, the first embryonic membrane, which detaches immediately before katatrepsis. The second period of embryonic growth—from kata…

Diflubenzuron-Induced alterations during in vitro development ofTenebrio molitor pupal integument

1987

The effects of diflubenzuron (DFB) in Tenebrio molitor pupae were first investigated on cuticle secretion induced by 20-hydroxyecdysone in vitro. The sternal integuments were treated by DFB either 3 days before culture or during culture. DFB, when applied before culture, did not prevent the molting hormone from inducing a new cuticle deposition by integument explants in vitro. However, this cuticle showed several architectural alterations and a thickness reduction. When applied during the culture in the presence of 20-hydroxyecdysone, DFB at high dose (≥ 20 μg/ml) was able to inhibit cuticle secretion, but lower doses (⩽ 10 μg/ml) resulted in epicuticle deposition. These observations confir…