Epicuticle Research Articles

Salix ×browiczii (Salicaceae) – a new nothospecies from northeastern Greece

A hybrid between Salix triandra and S. xanthicola, occurring in the Rhodope Mountains in northeastern Greece, is described as a new nothospecies. It differs from S. triandra by having distinctly hairy young stems and more deeply serrate-dentate leaf margins, and from S. xanthicola by a smooth, unstructured (without conicoids) wax layer on the lower side of the leaves and the presence of subsessile glands on the petioles.

A Comparative Evaluation of Apical Microleakage in Immediate vs Delayed Postspace Preparation using Four Endodontic Sealers seen under Stereomicroscope - An in vitro study

Context: An In-vitro research. Introduction: To evaluate the apical microleakage in immediate v/s delayed postspace preparation using four endodontic sealers; Endomethasone N, AH Plus, MTA Fillapex and Gutta Flow. Materials and Methods: One hundred and thirty recently excised single-rooted permanent teeth without caries were decorated. The postspace was created with a Peeso reamer from size 1–4, and 5 mm of gutta-percha was left after the root canals were biomechanically prepared up to F3 (ProTaper file) and obturated using the lateral condensation method. According to immediate and delayed postspace preparation, the samples were separated into eight groups, with 15 samples in each experimental group and 5 samples in each of the two control groups. Except for the apical 2 mm and the negative group, which were entirely sealed with two layers of sticky wax, all of the samples were covered with two layers of oppressive wax. Then, the samples were immersed in 2% methylene blue dye, centrifuged at 3000 rpm for 3 min, sectioned longitudinally and observed the extent of dye penetration under stereomicroscope. To compare the results between study groups and within each group, the Post hoc Tukey’s honestly significant difference comparison test and one-way ANOVA were utilized. When the P value was proved to be less than 0.05, the findings were deemed statistically significant. Results: Between all experimental groups, all samples revealed statistically significant differences. Group V (Endomethasone N-D) 3.46 ± 0.26 showed the greatest microleakage, whereas Group II (AH Plus I) 1.50 ± 0.40 showed little microleakage. Conclusions: Within the constraints of this study, postspace that was promptly prepared with all sealers experienced much-reduced microleakage.

In vitro analysis of durability of S-PRG filler-containing composite crowns for primary molar restoration.

To evaluate the reliability, maximum principal stress, shear stress, and crack initiation of a computer-aided design/computer-aided manufacturing (CAD/CAM) resin composite (RC) incorporating surface pre-reacted glass (S-PRG) filler for primary molar teeth. Mandibular primary molar crowns fabricated by experimental (EB) or commercially available CAD/CAM RCs (HC) were prepared and cemented to a resinous abutment tooth using an adhesive resin cement (Cem) or a conventional glass-ionomer cement (CX). These specimens were subjected to a single compressive test (n=5/each) and the step-stress accelerated life testing (SSALT) (n=12/each). Data was evaluated using Weibull analyses and reliability was calculated. Afterwards, the maximum principal stress and crack initiation point of each crown was analyzed by finite element analysis. To evaluate bonding of EB and HC to dentin, microtensile bond strength (μTBS) testing was conducted using primary molar teeth (n=10/each). There was no significant difference between the fracture loads of EB and HC for either cement (p>0.05). The fracture loads of EB-CX and HC-CX were significantly lower than EB-Cem and HC-Cem (p<0.05). The reliability at 600N for EB-Cem was greater than that for EB-CX, HC-Cem, and HC-CX. The maximum principal stress concentrated on EB was lower than that on HC. The shear stress concentrated in the cement layer for EB-CX was higher than that for HC-CX. There was no significant difference among the μTBSs of EB-Cem, EB-CX, HC-Cem, and HC-CX (p>0.05). The crowns fabricated with the experimental CAD/CAM RC incorporating S-PRG filler yielded greater fracture loads and reliability than the crowns manufactured with commercially available CAD/CAM RC regardless of the luting materials. These findings suggest that the experimental CAD/CAM RC crown may be clinically useful for the restoration of primary molars.

Anisotropic optical response of the cuticle of arthropods

Anisotropic optical response of the cuticle of arthropods

Post-fatigue fracture load, stress concentration and mechanical properties of feldspathic, leucite- and lithium disilicate-reinforced glass ceramics

ObjectiveTo evaluate the mechanical properties of different CAD/CAM ceramic systems and the post-fatigue fracture and stress distribution when used as cemented crowns. Materials and methodsSixty (60) CAD/CAM monolithic crowns were milled using three different ceramic materials (FD – Feldspathic [Vita Mark II]), LE - Leucite-based ceramic [IPS Empress CAD] and LD - Lithium Disilicate [IPS e.max CAD]) and adhesively cemented on resin composite dyes. Specimens were stored in distillated water (37 °C) for 7 days. After, half of the crowns were submitted to immediate fracture load test while the other half was submitted to fatigue cycling. The average cement layer of approximately 80 μm was assessed using scanning electron microscopy (SEM). The average thickness was used in the three-dimensional (3D) Finite Element Analysis (FEA). For each ceramic material, the density, Poisson ratio, shear modulus, Young modulus, fracture toughness, and true hardness were assessed (n = 3). The data was used to assess the Maximum Principal Stress throughout 3D-FEA according to each material during load to fail and post-fatigue. Data were submitted to two-way ANOVA and Tukey test (α = 0.05). ResultsLD showed the highest compression load, density, shear modulus, Young modulus, fracture toughness and true hardness values. While LE presented the lowest mechanical properties values. There is no difference in the Poisson ratio between the evaluated ceramics. ConclusionLD was susceptible to aging process but presented stronger physicomechanical properties, showing the highest post-fatigue fracture load and highest stress magnitude.

Species-specific influence of powdery mildew mycelium on the efficiency of PM accumulation by urban greenery

Particulate matter (PM) is one of the most important air pollutants, especially in urban areas. The efficiency of PM biofiltration by plants depends on the morphological features of the foliage. More PM is deposited on complex leaves, covered with thick wax layer, trichomes, epidermal glands, and convex venation. Very few literature reports suggest that also the presence of mycelium of nonparasitic and saprophytic fungi positively affects the accumulation of PM on the leaves. In this work, to our best knowledge, for the first time the effect of the mycelium of the parasitic powdery mildew on the efficiency of PM accumulation by urban greenery was studied. Uninfested and fungus-infested leaves of Acer negundo L., Malus domestica Borkh Quercus robur L., and Berberis vulgaris L. were harvested in July in the center of Warsaw city. The effect of powdery mildew infection on PM accumulation was species-specific. A higher amount of PM on leaves not infected with powdery mildew was found in M. domestica and Q. robur, while in A. negundo and B. vulgaris more PM was accumulated on leaves infected with fungus. All species (except A. negundo) accumulated more of the PM of 0.2–2.5-μm and 2.5–10-μm size fractions on leaves not infected with powdery mildew. One of the greatest consequences of the presence of powdery mildew mycelium on the foliage is most probably reduction of the direct involvement of waxes in PM accumulation and retention processes.

Cuticular profiling of insecticide resistant Aedes aegypti

Insecticides have made great strides in reducing the global burden of vector-borne disease. Nonetheless, serious public health concerns remain because insecticide-resistant vector populations continue to spread globally. To circumvent insecticide resistance, it is essential to understand all contributing mechanisms. Contact-based insecticides are absorbed through the insect cuticle, which is comprised mainly of chitin polysaccharides, cuticular proteins, hydrocarbons, and phenolic biopolymers sclerotin and melanin. Cuticle interface alterations can slow or prevent insecticide penetration in a phenomenon referred to as cuticular resistance. Cuticular resistance characterization of the yellow fever mosquito, Aedes aegypti, is lacking. In the current study, we utilized solid-state nuclear magnetic resonance spectroscopy, gas chromatography/mass spectrometry, and transmission electron microscopy to gain insights into the cuticle composition of congenic cytochrome P450 monooxygenase insecticide resistant and susceptible Ae. aegypti. No differences in cuticular hydrocarbon content or phenolic biopolymer deposition were found. In contrast, we observed cuticle thickness of insecticide resistant Ae. aegypti increased over time and exhibited higher polysaccharide abundance. Moreover, we found these local cuticular changes correlated with global metabolic differences in the whole mosquito, suggesting the existence of novel cuticular resistance mechanisms in this major disease vector.

Blastospores from Metarhizium anisopliae and Metarhizium rileyi Are Not Always as Virulent as Conidia Are towards Spodoptera frugiperda Caterpillars and Use Different Infection Mechanisms.

Infective conidia from entomopathogenic fungi are widely used to control insect pests. Many entomopathogenic fungi also produce yeast-like cells called blastospores under specific liquid culture conditions that can directly infect insects. However, little is known about the biological and genetic factors that allow blastospores to infect insects and make them potentially effective for biological control in the field. Here, we show that while the generalist Metarhizium anisopliae produces a higher number of and smaller blastospores, the Lepidoptera specialist M. rileyi produces fewer propagules with a higher cell volume under high-osmolarity conditions. We compared the virulence of blastospores and conidia of these two Metarhizium species towards the economically important caterpillar pest Spodoptera frugiperda. Conidia and blastospores from M. anisopliae were equally infectious, but acted slower, and killed fewer insects than M. rileyi conidia and blastospores did, where M. rielyi conidia had the highest virulence. Using comparative transcriptomics during propagule penetration of insect cuticles, we show that M. rileyi blastospores express more virulence-related genes towards S. frugiperda than do M. anisopliae blastospores. In contrast, conidia of both fungi express more virulence-related oxidative stress factors than blastospores. Our results highlight that blastospores use a different virulence mechanism than conidia use, which may be explored in new biological control strategies.

Identification of cuticular protein genes and analysis of their roles in phosphine resistance of the rusty grain beetle Cryptolestes ferrugineus

The rusty grain beetle, Cryptolestes ferrugineus (Stephens) is one of the most economically important stored grain pests, and it has evolved the high resistance to phosphine. Cuticular proteins (CPs) are the major structural components of insect cuticle, and previous studies have confirmed that CPs were involved in insecticide resistance. However, the CPs of C. ferrugineus are still poorly characterized, and thus we conducted transcriptome-wide identification of CP genes and analyze their possible relationships with phosphine resistance in this pest. In this study, a total of 122 putative CPs were annotated in the C. ferrugineus transcriptome data by blasting with the known CPs of Tribolium castaneum. The analysis of conserved motifs revealed these CPs of C. ferrugineus belonging to 9 different families, including 87 CPR, 13 CPAP1, 7 CPAP3, 3 Tweedle, 1 CPLCA, 1 CPLCG, 5 CPLCP, 2 CPCFC, and 3 CPFL proteins. The further phylogenetic analysis showed the different evolutionary patterns of CPs. Namely, we found some CPs (CPR family) formed species-specific protein clusters, indicating these CPs might occur independently among insect taxa, and while some other CPs (CPAP1 and CPAP3 family) shared a closer correlation based on the architecture of protein domains. Subsequently, the previous RNA-seq data were applied to establish the expression profiles of CPs in a phosphine susceptible and resistant populations of C. ferrugineus, and a large amount of CP genes were found to be over-expressed in resistant insects. Lastly, an up-regulated CP gene (CPR family) was selected for the further functional analysis, and after this gene was silenced via RNA interference (RNAi), the sensitivity to phosphine was significantly enhanced in C. ferrugineus. In conclusion, the present results provided us an overview of C. ferrugineus CPs, and which suggested that the CPs might play the critical roles in phosphine resistance.

Lipids as a key element of insect defense systems.

The relationship between insect pathogenic fungi and their insect hosts is a classic example of a co-evolutionary arms race between pathogen and target host: parasites evolve towards mechanisms that increase their advantage over the host, and the host increasingly strengthens its defenses. The present review summarizes the literature data describing the direct and indirect role of lipids as an important defense mechanism during fungal infection. Insect defense mechanisms comprise anatomical and physiological barriers, and cellular and humoral response mechanisms. The entomopathogenic fungi have the unique ability to digest the insect cuticle by producing hydrolytic enzymes with chitin-, lipo- and proteolytic activity; besides the oral tract, cuticle pays the way for fungal entry within the host. The key factor in insect resistance to fungal infection is the presence of certain types of lipids (free fatty acids, waxes or hydrocarbons) which can promote or inhibit fungal attachment to cuticle, and might also have antifungal activity. Lipids are considered as an important source of energy, and as triglycerides are stored in the fat body, a structure analogous to the liver and adipose tissue in vertebrates. In addition, the fat body plays a key role in innate humoral immunity by producing a range of bactericidal proteins and polypeptides, one of which is lysozyme. Energy derived from lipid metabolism is used by hemocytes to migrate to the site of fungal infection, and for phagocytosis, nodulation and encapsulation. One polyunsaturated fatty acid, arachidonic acid, is used in the synthesis of eicosanoids, which play several crucial roles in insect physiology and immunology. Apolipoprotein III is important compound with antifungal activity, which can modulate insect cellular response and is considered as important signal molecule.

Surfactants Improving the Wetting Behavior and Adhesion Mechanism of Pesticide Dilution Droplets on Jujube Leaf Surfaces.

Fruit tree leaves have different chemical compositions and diverse wax layer structures that result in different patterns of wetting and pesticide solution spreading on their surface. Fruit development is a time when pests and diseases occur, during which a large number of pesticides are needed. The wetting and diffusion properties of pesticide droplets on fruit tree leaves were relatively poor. To solve this problem, the wetting characteristics of leaf surfaces with different surfactants were studied. The contact angle, surface tension, adhesive tension, adhesion work, and solid-liquid interfacial tension of five surfactant solution droplets on jujube leaf surfaces during fruit growth were studied by the sessile drop method. C12E5 and Triton X-100 have the best wetting effects. Two surfactants were added to a 3% beta-cyfluthrin emulsion in water, and field efficacy tests were carried out on peach fruit moths in a jujube orchard at different dilutions. The control effect is as high as 90%. During the initial stage when the concentration is low, due to the surface roughness of the leaves, the surfactant molecules adsorbed at the gas-liquid and solid-liquid interfaces reach an equilibrium, and the contact angle on the leaf surface changes slightly. With increasing surfactant concentration, the pinning effect in the spatial structure on the leaf surface is overcome by liquid droplets, thereby significantly decreasing the contact angle. When the concentration is further increased, the surfactant molecules form a saturated adsorption layer on the leaf surface. Due to the existence of a precursor water film in the droplets, surfactant molecules on the interface continuously move to the water film on the surface of jujube tree leaves, thus causing interactions between the droplets and the leaves. The conclusion of this study provides theoretical guidance for the wettability and adhesion of pesticides on jujube leaves, so as to achieve the purpose of reducing pesticide use and improving pesticide efficacy.

Testing for adaptive changes linked to range expansion following a single introduction of the fall webworm.

Adaptive evolution following colonization can affect the impact of invasive species. The fall webworm (FWW) invaded China 40 years ago through a single introduction event involving a severe bottleneck and subsequently diverged into two genetic groups. The well-recorded invasion history of FWW, coupled with a clear pattern of genetic divergence, provides an opportunity to investigate whether there is any sign of adaptive evolution following the invasion. Based on genome-wide SNPs, we identified genetically separated western and eastern groups of FWW and correlated spatial variation in SNPs with geographical and climatic factors. Geographical factors explained a similar proportion of the genetic variation across all populations compared with climatic factors. However, when the two population groups were analysed separately, environmental factors explained more variation than geographical factors. SNP outliers in populations of the western group had relatively stronger response to precipitation than temperature-related variables. Functional annotation of SNP outliers identified genes associated with insect cuticle protein potentially related to desiccation adaptation in the western group and genes associated with lipase biosynthesis potentially related to temperature adaptation in the eastern group. Our study suggests that invasive species may maintain the evolutionary potential to adapt to heterogeneous environments despite a single invasion event. The molecular data suggest that quantitative trait comparisons across environments would be worthwhile.

Role of cuticle-degrading enzymes of Beauveria bassiana and Metarhizium anisopliae in virulence on Plodia interpunctella (Lepidoptera, Pyralidae) larvae

Entomopathogenic fungi (EPF) are important biological control agents in pest management programs in agroecosystems against insect pests. EPF such as Beauveria bassiana (Bals.) Vuillemin and Metarhizium anisopliae (Metchn.) Sorokin produce a wide range of extracellular enzymes involved in disturbance of the first barrier in the insect cuticle comprising proteins, chitin, and lipids. Realizing relationships between the expression of these enzymes and fungal virulence might aid in development of effective mycoinsecticides. The virulence of B. bassiana (isolates TV and OZ1) and M. anisopliae (isolate CS1) were investigated on Plodia interpunctella (Hübner) larvae in this study. The third instar larvae were immersed in a suspension containing 1 × 108 conidia.mL-1 of fungal conidial inoculum. The results revealed that all three fungal isolates caused mortality in larvae, but there was a considerable variation in their virulence. Total proteinase, exochitinase and lipase assays were done for these isolates. The TV isolate with the highest mortality with 41.7%, had the highest level of specific activity of exochitinase, protease, and lipase with 0.148, 0.654, and 0.190 U. mg-1 protein, respectively. In the current study, a positive correlation was determined between the virulence of fungal isolates and the activities of protease and lipase, but this link was not significant for exochitinase. Our results demonstrated that extracellular enzymes, particularly protease and lipase, may play a crucial role in the virulence of these fungal isolates against P. interpunctella larvae.

Comparative Studies on Leaf Micromorphology of the Abaxial Surface of Quercus robur L. subsp. robur and Quercus robur L. subsp. pedunculiflora (K. KOCH) MENITSKY

This study examined micromorphological traits on the abaxial surface of leaves using a Scanning Electron Microscope (SEM) to compare pedunculate oak and greyish oak taxa close-up. We selected a pedunculate oak population in Hungary and greyish oak population in Romania. The study randomly selected trees over 100 years old from these populations to investigate the differences between the two taxa based on leaf micromorphological characteristics. We focused mainly on indumentum because observing trichomes can be used in practice. Variation was found in trichome types, trichome-ray lengths, and stomata extent and shape. Stellate and fasciculate trichomes were absent on pedunculate oak leaves and densely developed on greyish oak leaves. The average length of the simple-uniseriate trichomes of pedunculate oak was 49.45 μm and 61.96 μm in greyish oak. On average, stomata surfaces on pedunculate oak leaves were 513.09 μm2 and 440.28 μm2 on greyish oak leaves. The study found no variation in epicuticular wax layer type. Despite the small sample size, in comparing the two populations, we found that the two taxa were distinguishable based on trichome types, and we believe that forestry practice could utilise this trait.

РАЗРАБОТКИ ПОДПРОГРАММЫ «МЕТАЛЛУРГИЯ», ВЫПОЛНЕННЫЕ В ИНТЕРЕСАХ ПРОМЫШЛЕННЫХ ПРЕДПРИЯТИЙ

The main results of the implementation of the tasks of the subprogram “Metallurgy” of the State Research Program “Mechanics, Metallurgy, Diagnostics in Mechanical Engineering”, 2021–2025, with an applied orientation are presented, which are obtained by the organizations of the National Academy of Sciences of Belarus, the Ministry of Education and the Ministry of Industry of the Republic of Belarus. Their contribution to the solution of practical problems is shown. In the field of metallurgy of iron-carbon alloys, a range of new grades of steels for large gears and large castings of supporting systems of machines are developed. Distinctive features of the developed steels are the possibility to obtain higher hardness values of the hardened layer and teeth of cemented gears compared with counterparts from serial steels. A new sparingly alloyed steel for gearboxes of tractors BELARUS has been developed. The steel is characterized by high hardenability of cemented layer. In the field of metallurgy of non-ferrous metals and alloys, theoretical and technological bases for production of complex configuration castings are developed. Application of these castings improves the dimensional accuracy of products. In the field of hardening of steels and alloys, the technology of coating formation on the working surfaces of metallurgical and foundry equipment parts by mechanical cladding with flexible tool is developed. The coatings provide 1.9 times higher durability of mold parts by compared to the parts without coatings. The technological process of induction cladding on the surfaces of friction nodes parts of wear-resistant antifriction coatings is developed. The service life of bimetallic parts with coatings is 1.25–1.33 times higher than that of serial parts. Physico-chemical principles of creation of aluminomatrix composites were developed on the basis of micro- and ultradispersed oxide powders. This provided a 5-fold increase in tribomechanical properties. In the field of metal forming, the strategy of ring rolling is developed as applied to the nomenclature of rings of the Belarusian enterprises. Technological substantiation is performed for reducing deformations and residual stresses after heat treatment of low-rigid parts such as discs using dynamic stabilization based on alternating cyclic loading.

Intraradicular Diameter, Remnant Dentin Thickness, and Endodontic Post to Dentin Distance: CBCT and Microscopic Analyses

The objective of this work was to measure the tooth root canals’ diameter, remnant dentin thickness, endodontic post to dentin distance, and resin-matrix cement layer after three types of root canal shaping. Thirty extracted human premolars were endodontically treated and groups of specimens were divided according to the cementation with two different endodontic posts as follow: A) Fibio Fiberglass Post™, Anthogyr, France; B) multi-filament GFRC (Rebilda GT™, VOCO, Germany). Cone beam computed tomography (CBCT) and conventional X-ray analyses were performed before and after the endodontic post cementation. After cementation, specimens were cross-sectioned and inspected by optical microscopy and scanning electron microscopy at magnification ranging from × 30 up to × 2000. Changes in shaping of the root canals caused a decrease in the thickness of the remnant tooth tissues. CBCT and microscopic analyses also revealed a clear variation of resin-matrix cement around the glass fiber-reinforced composite (GFRC) posts. A multi-filament GFRC post provided an adequate distribution of filaments although the resin-matrix cement revealed a high volume among the filaments. An increase in thickness and volume of resin-matrix cement was noticed at the coronal third since the fitting was compromised due to tooth anatomic variations and root canal preparation. Defects such macro-scale pores, cracks, and voids were also detected by microscopic analyses. The root canal shaping can promote a decrease in the thickness of the remnant tooth tissues that can increase the risks of clinical failures by fracture. The thickness and volume of resin-matrix cement varied around both GFRC posts and increased from the apex up to the coronal third due to the lack of fitting.Graphical

Genome-wide analysis of cuticle protein family genes in rice stem borer Chilo suppressalis: Insights into their role in environmental adaptation and insecticidal stress response

Insect cuticle plays a key role in insect survival, adaptation and prosperity by serving as the exoskeleton and the first barrier against environmental stresses. As the major components of insect cuticle, the diverse structural cuticle proteins (CPs) contribute to variation in physical properties and functions of cuticle. However, the roles of CPs in cuticular versatility, especially in the stress response or adaption, remain incompletely understood. In this study, we performed a genome-wide analysis of CP superfamily in the rice-boring pest Chilosuppressalis. A total of 211 CP genes were identified and their encoding proteins were classified into eleven families and three subfamilies (RR1, RR2, and RR3). The comparative genomic analysis of CPs revealed that C. suppressalis had fewer CP genes compared to other lepidopteran species, which largely resulted from a less expansion of his-rich RR2 genes involved in cuticular sclerotization, suggesting long-term boring life of C. suppressalis inside rice hosts might evolutionarily prefer cuticular elasticity rather than cuticular sclerotization. We also investigated the response pattern of all CP genes under insecticidal stresses. >50 % CsCPs were upregulated at least 2-fold under insecticidal stresses. Notably, the majority of the highly upregulated CsCPs formed gene pairs or gene clusters on chromosomes, indicating the rapid response of adjacent CsCPs to insecticidal stress. Most high-response CsCPs encoded AAPA/V/L motifs that are related to cuticular elasticity and >50 % of the sclerotization-related his-rich RR2 genes were also upregulated. These results suggested the potential roles of CsCPs in balancing the elasticity and sclerotization of cuticles, which is essential for the survival and adaptation of plant borers including C. suppressalis. Our study provides valuable information for further developing cuticle-based strategies of both pest management and biomimetic applications.

An environmentally friendly bio-based wood adhesive prepared via a green and mild method inspired by insect cuticle

Biobased adhesives have the potential to replace traditional adhesives because they are sustainable, biodegradable, and environmentally-friendly. This work presents a simple and effective strategy inspired by the insect exoskeleton hardening mechanism to react pyrogallol (PG, derived from gallnut) and branched polyamines (PAXN) into a high-performance and environmentally-friendly wood adhesive. Pyrogallol was oxidized (donated as OPG) with the aid of NaOH at room temperature to convert its phenolic hydroxyl group to quinone group, then the quinone group is cross-linked with PAXN by a Schiff base reaction to obtain the OPG-PAXN adhesive. The bonding performance of the bio-based adhesive was studied systematically, which shows that the optimal mass ratio of OPG/PAXN is 1:1, and the best performance was obtained with a solid content of 50%. The dry strength of the OPG-PA6 N adhesive reached 2.22 MPa, and the wet strength increased from 0 to 1.85 MPa. Furthermore, 13C NMR, FTIR, XPS, and other characterizations showed that OPG-PA6 N network was formed by imine bond. TG and DSC results indicated that the thermal properties of OPG-PA6 N adhesive was significantly enhanced compared with those of OPG or PA6 N. The proposed bio-based adhesive is expected to become a potential substitute for the traditional formaldehyde-based adhesive.

Ergot Alkaloids Contribute to the Pathogenic Potential of the Fungus Aspergillus leporis.

Opportunistically pathogenic fungi have varying potential to cause disease in animals. Factors contributing to their virulence include specialized metabolites, which in some cases evolved in contexts unrelated to pathogenesis. Specialized metabolites that increase fungal virulence in the model insect Galleria mellonella include the ergot alkaloids fumigaclavine C in Aspergillus fumigatus (syn. Neosartorya fumigata) and lysergic acid α-hydroxyethylamide (LAH) in the entomopathogen Metarhizium brunneum. Three species of Aspergillus recently found to accumulate high concentrations of LAH were investigated for their pathogenic potential in G. mellonella. Aspergillus leporis was most virulent, A. hancockii was intermediate, and A. homomorphus had very little pathogenic potential. Aspergillus leporis and A. hancockii emerged from and sporulated on dead insects, thus completing their asexual life cycles. Inoculation by injection resulted in more lethal infections than did topical inoculation, indicating that A. leporis and A. hancockii were preadapted for insect pathogenesis but lacked an effective means to breach the insect's cuticle. All three species accumulated LAH in infected insects, with A. leporis accumulating the most. Concentrations of LAH in A. leporis were similar to those observed in the entomopathogen M. brunneum. LAH was eliminated from A. leporis through a CRISPR/Cas9-based gene knockout, and the resulting strain had reduced virulence to G. mellonella. The data indicate that A. leporis and A. hancockii have considerable pathogenic potential and that LAH increases the virulence of A. leporis. IMPORTANCE Certain environmental fungi infect animals occasionally or conditionally, whereas others do not. Factors that affect the virulence of these opportunistically pathogenic fungi may have originally evolved to fill some other role for the fungus in its primary environmental niche. Among the factors that may improve the virulence of opportunistic fungi are specialized metabolites--chemicals that are not essential for basic life functions but provide producers with an advantage in particular environments or under specific conditions. Ergot alkaloids are a large family of fungal specialized metabolites that contaminate crops in agriculture and serve as the foundations of numerous pharmaceuticals. Our results show that two ergot alkaloid-producing fungi that were not previously known to be opportunistic pathogens can infect a model insect and that, in at least one of the species, an ergot alkaloid increases the virulence of the fungus.

Mechanical properties of larval mouthparts of the antlion Euroleon nostras (Neuroptera: Myrmeleontidae) and their correlation with cuticular material composition

The diversity of insects can be explained by their ability to fill various ecological niches, which includes the foraging from diverse sources. The cuticle-based feeding structures interact with the food and show adaptations in shape, material composition and mechanical properties to it. In this study, we focus on the mouthparts of a very prominent ambush predator, the antlion larvae of Euroleon nostras. By nanoindentation, we tested the hardness and the Young’s modulus of the mouthparts, which are significantly harder and stiffer than other insect cuticle structures. To gain insight into the origins of the high values, we studied the degree of tanning using confocal laser scanning microscopy. Additionally, we determined the content of transition and alkaline earth metals by energy dispersive X-ray spectroscopy. We found that the proportions of Zn, Mn, Fe, Cu, Ca, Mg, and Si correlate with the mechanical property values. We also conducted experiments on the breaking stress, the puncturing and biomechanical behaviour of the jaws, which highlighted their extraordinary strength. These findings are not only valuable for biologists, but also for material scientists, as they contribute to our understanding of the origins of mechanical property heterogeneities in insect cuticle.