The First Study on Nuclear Polyhedrosis Virus Histopathological and Morphological Effects on the Strawberry Pest, Pentodon Algerinum (coleoptera: Scarabaeidae)

In Egypt, strawberry is an economically important crop that has recently been destroyed by Pentodon algerinum, a worldwide polyphagous destructive insect pest. This study aimed to distinguish, for the first time, the histopathological and morphological effects of Spodoptera littoralis Nuclear polyhedrosis virus (SpliNPV) and Pentodon algerinum Nuclear polyhedrosis virus (PNPV) on Pentodon algerinum third instar larvae to confirm their success as safe alternative control agents against this pest. The results showed that PNPV and SpliNPV affected Pentodon larvae by the same effects in causing the following: integument deformation and rupture; the destruction of the hypodermal layer resulting in the inhibition of the process of molting into the pupa stage, reducing pest survival; larva leg corrosion, which prevents its spreading; the rupture of fat bodies, which leads to the loss of stored energetic materials; the distortion of muscle sarcolemma and fibers resulting in weakness and softness; the tracheal cuticular layer destruction, which inhibits breathing; midgut rupture with cells detaching from each other; irregular cytoplasm distribution; the loss of the columnar shape of cells; the appearance of vacuoles between cells, which results in their inability to feed or to digest; the swelling, softness, liquefaction, and, lastly, death of the larva.

Chitin and cuticle proteins form the cuticular layer in the spinning duct of silk-spinning arthropods

Chitin is found in the exoskeleton and peritrophic matrix of arthropods, but recent studies have also identified chitin in the spinning duct of silk-spinning arthropods. Here, we report the presence and function of chitin and cuticle proteins ASSCP1 and ASSCP2 in the spinning duct of silkworms. We show that chitin and these proteins are co-located in the cuticular layer of the spinning duct. Ultrastructural analysis indicates that the cuticular layer has a multilayer structure by layered stacking of the chitin laminae. After knocking down ASSCP1 and ASSCP2, the fine structure of this layer was disrupted, which had negative impacts on the mechanical properties of silk. This work clarifies the function of chitin in the spinning duct of silk-spinning arthropods. Chitin and cuticle proteins are the main components of the hard and rigid cuticular layer, providing the shearing stress during silk fibrillogenesis and regulating the final mechanical properties of silk.

Asymmetric water transport in dense leaf cuticles and cuticle-inspired compositionally graded membranes

Most of the aerial organs of vascular plants are covered by a protective layer known as the cuticle, the main purpose of which is to limit transpirational water loss. Cuticles consist of an amphiphilic polyester matrix, polar polysaccharides that extend from the underlying epidermal cell wall and become less prominent towards the exterior, and hydrophobic waxes that dominate the surface. Here we report that the polarity gradient caused by this architecture renders the transport of water through astomatous olive and ivy leaf cuticles directional and that the permeation is regulated by the hydration level of the cutin-rich outer cuticular layer. We further report artificial nanocomposite membranes that are inspired by the cuticles’ compositionally graded architecture and consist of hydrophilic cellulose nanocrystals and a hydrophobic polymer. The structure and composition of these cuticle-inspired membranes can easily be varied and this enables a systematic investigation of the water transport mechanism.

Cuticular Chemistry of the Queensland Fruit Fly Bactrocera tryoni (Froggatt)

The cuticular layer of the insect exoskeleton contains diverse compounds that serve important biological functions, including the maintenance of homeostasis by protecting against water loss, protection from injury, pathogens and insecticides, and communication. Bactrocera tryoni (Froggatt) is the most destructive pest of fruit production in Australia, yet there are no published accounts of this species’ cuticular chemistry. We here provide a comprehensive description of B. tryoni cuticular chemistry. We used gas chromatography-mass spectrometry to identify and characterize compounds in hexane extracts of B. tryoni adults reared from larvae in naturally infested fruits. The compounds found included spiroacetals, aliphatic amides, saturated/unsaturated and methyl branched C12 to C20 chain esters and C29 to C33 normal and methyl-branched alkanes. The spiroacetals and esters were found to be specific to mature females, while the amides were found in both sexes. Normal and methyl-branched alkanes were qualitatively the same in all age and sex groups but some of the alkanes differed in amounts (as estimated from internal standard-normalized peak areas) between mature males and females, as well as between mature and immature flies. This study provides essential foundations for studies investigating the functions of cuticular chemistry in this economically important species.

Monitoring of changes in 5-n-alkylresorcinols during wheat seedling development

For seven days of wheat growth, caryopsis remained the main source of 5-n-alkylresorcinols with C19 and/or C21 homolog as a main compound. Shoot contained small amount of these phenolic lipids; their average content was 3.23% of level obtained in the whole seedling. Moreover, 41.38% of resorcinolic lipids of seven-day-old shoot was accumulated in part of leaf covered by coleoptile. Interestingly, a removal of 1.07% of the primary pool of kernel alkylresorcinols by short-term washing (10 s) of wheat seed with acetone before planting decreased their level only in seed of seven-day old seedling. Compared to the respective controls, this treatment did not affect the amount of these lipids in the green part of seedling that proved that de novo synthesis of 5-n-alkylresorcinols takes place in shoots. The very similar homolog profiles of these lipids in four- and seven-day-old shoots turned out to be markedly less diversified than those found in respective seed samples. Compared to the mature wheat caryopsis, the rise in the content of very-long-chain homologs was observed only in the oldest shoot. Their increased accumulation was probably connected with formation of cuticular layer providing the defensive barrier against various phytopathogens.

Cerebral Coenurosis Masquerading as Malignancy: A Rare Case Report from India

ABSTRACTHuman coenurosis is a rare zoonotic disease caused by the larvae of Tinea multiceps seen in sheep-rearing countries. We report the case of a 63-year-old male who was referred to our hospital with a working diagnosis of skull base chondrosarcoma. Histopathological examination after surgical excision revealed characteristic feature of coenurus with multiple scolices invaginating from the outer cuticular layer. Coenuri are often mistaken for giant cysticercal cysts and hydatid cysts. Despite its wide prevalence in cattle, only two cases of human coenurosis are reported from India till date. We report the third case from India.

Structural origins of coloration in the spider Phoroncidia rubroargentea Berland, 1913 (Araneae: Theridiidae) from Madagascar

This study investigates the structural basis for the red, silver and black coloration of the theridiid spider, Phoroncidia rubroargentea (Berland, 1913) from Madagascar. Specimens of this species can retain their colour after storage in ethanol for decades, whereas most other brightly pigmented spider specimens fade under identical preservation conditions. Using correlative optical, structural and chemical analysis, we identify the colour-generating structural elements and characterize their optical properties. The prominent silvery appearance of the spider's abdomen results from regularly arranged guanine microplatelets, similar to those found in other spiders and fish. The microplatelets are composed of a doublet structure twinned about the [ ] axis, as suggested by electron diffraction. The red coloration originates from chambered microspheres (approx. 1 µm in diameter), which contain structured fluorescent material. Co-localization of the red microparticles on top of the reflective guanine microplatelets appears to enhance the red coloration. The spider's thick cuticular layer, which encases its abdomen, varies in its optical properties, being transparent in regions where only guanine reflectors are present, and tanned, exhibiting light absorption where the red microspheres are found. Moreover, colour degradation in some preserved spider specimens that had suffered damage to the cuticular layer suggests that this region of the exoskeleton may play an important role in the stabilization of the red coloration.

How do cuticular hydrocarbons evolve? Physiological constraints and climatic and biotic selection pressures act on a complex functional trait

Cuticular hydrocarbons (CHCs) cover the cuticles of virtually all insects, serving as a waterproofing agent and as a communication signal. The causes for the high CHC variation between species, and the factors influencing CHC profiles, are scarcely understood. Here, we compare CHC profiles of ant species from seven biogeographic regions, searching for physiological constraints and for climatic and biotic selection pressures. Molecule length constrained CHC composition: long-chain profiles contained fewer linear alkanes, but more hydrocarbons with disruptive features in the molecule. This is probably owing to selection on the physiology to build a semi-fluid cuticular layer, which is necessary for waterproofing and communication. CHC composition also depended on the precipitation in the ants' habitats. Species from wet climates had more alkenes and fewer dimethyl alkanes than those from drier habitats, which can be explained by different waterproofing capacities of these compounds. By contrast, temperature did not affect CHC composition. Mutualistically associated (parabiotic) species possessed profiles highly distinct from non-associated species. Our study is, to our knowledge, the first to show systematic impacts of physiological, climatic and biotic factors on quantitative CHC composition across a global, multi-species dataset. We demonstrate how they jointly shape CHC profiles, and advance our understanding of the evolution of this complex functional trait in insects.

A new species of Postia (Basidiomycota) based on morphological and molecular characteristics

A new wood-decaying polypore from southern China, Postia cylindrica, is described and illustrated using morphological characteristics and rDNA ITS sequences. The new species is characterized by resupinate to effused reflexed basidiocarps, cream to buff and azonate pileal surface, reddish-brown and incurved margin, gloeoplerous hyphal cells in cuticular layer, absence of cystidia, and cylindrical, thin-walled basidiospores. Molecular analyses confirm the phylogenetic position of the new species Postia. The discriminating characters of the new species and the closely related species are discussed.