The mechanical properties of the mussel byssal thread have been investigated via nanoindentation, with the emphasis on the differences between the cuticle and the fibrous interior. The cuticle hardness was found to be 30-40% higher than that of the underlying fibrous interior. In contrast, the Young’s moduli in the two regions were virtually identical to one another. Elemental analysis via ener...

Clearance of microfilariae from the circulation of hamsters infected with Dipetalonema viteae was demonstrated following passive transfer of serum obtained from hyperinfected hamsters. The exclusion fraction after gel filtration of this serum on Sephacryl S 200 also cleared microfilariae whereas the other fractions did not. There was no clearance with serum taken during the pre-patent, patent o...

Evidence obtained on the relation between the pH of the medium and the growth of intact stem sections is compatible with the acid-growth theory only if the proton conductance of the cuticle is so low that the cuticle is an effective barrier to the entry or exit of protons from the tissue. By measuring the rate at which protons cross frozen-thawed epidermal strips of sunflower (Helianthus annuus...

The cuticle of the scarab beetle Cotinis mutabilis reflects left-handed polarized light indicating the presence of a helicoidal structure. Different in-depth pitches in the cuticle are corroborated by optical microscopy images of the cuticle which originally is yellowish or reddish but becomes greenish after gently scratching its top side. Using the Mueller-matrix formalism the degree of polari...

When the diploid histoblasts, the precursors of adult abdominal epidermal cells, of the larva of Drosophila are deleted by gamma-radiation, the polytene larval epidermal cells survive metamorphosis and secrete cuticle and cuticular outgrowths. A comparison of the morphology of the cuticle secreted by the larval epidermal cells in the different regions of the abdominal segments to that secreted ...

Extracellular matrix barriers and inducible cytoprotective genes form successive lines of defense against chemical and microbial environmental stressors. The barrier in nematodes is a collagenous extracellular matrix called the cuticle. In Caenorhabditis elegans, disruption of some cuticle collagen genes activates osmolyte and antimicrobial response genes. Physical damage to the epidermis also ...

A plant cuticle forms a hydrophobic layer covering plant organs, and plays an important role in plant development and protection from environmental stresses. We examined epicuticular structure, composition, and a MYB-based regulatory network in two Australian wheat cultivars, RAC875 and Kukri, with contrasting cuticle appearance (glaucousness) and drought tolerance. Metabolomics and microscopic...

The nature of the interaction of insect cuticular proteins and chitin is unknown even though about half of the cuticular proteins sequenced thus far share a consensus region that has been predicted to be the site of chitin binding. We previously predicted the preponderance of beta-pleated sheet in the consensus region and proposed its responsibility for the formation of helicoidal cuticle (Icon...

All arthropods periodically molt to replace their exoskeleton (cuticle). Immediately after shedding the old cuticle, the neurohormone bursicon causes the hardening and darkening of the new cuticle. Here we show that bursicon, to our knowledge the first heterodimeric cystine knot hormone found in insects, consists of two proteins encoded by the genes burs and pburs (partner of burs). The pburs/b...

The lamellate appearance of the cuticle in the abdomen of the Rhodnius larva conforms to the conception of Bouligand in being an optical artifact which results from the spiral arrangement of successive layers of oriented fibrils. But superimposed on this structure is an actual lamination of bound lipid with the same spacing. The relation of the lipid layers to the optical lamination changes wit...