An ABCB transporter regulates anisotropic cell expansion via cuticle deposition in the moss Physcomitrium patens.

Anisotropic cell expansion is crucial for the morphogenesis of land plants, as cell migration is restricted by the rigid cell wall. The anisotropy of cell expansion is regulated by mechanisms acting on the deposition or modification of cell wall polysaccharides. Besides the polysaccharide components in the cell wall, a layer of hydrophobic cuticle covers the outer cell wall and is subjected to tensile stress that mechanically restricts cell expansion. However, the molecular machinery that deposits cuticle materials in the appropriate spatiotemporal manner to accommodate cell and tissue expansion remains elusive. Here, we report that PpABCB14, an ATP-binding cassette transporter in the moss Physcomitrium patens, regulates the anisotropy of cell expansion. PpABCB14 localized to expanding regions of leaf cells. Deletion of PpABCB14 resulted in impaired anisotropic cell expansion. Unexpectedly, the cuticle proper was reduced in the mutants, and the cuticular lipid components decreased. Moreover, induced PpABCB14 expression resulted in deformed leaf cells with increased cuticle lipid accumulation on the cell surface. Taken together, PpABCB14 regulates the anisotropy of cell expansion via cuticle deposition, revealing a regulatory mechanism for cell expansion in addition to the mechanisms acting on cell wall polysaccharides.

Repression of drought-induced cysteine-protease genes alters barley leaf structure and responses to abiotic and biotic stresses.

To survive under water deficiency, plants alter gene expression patterns, make structural and physiological adjustments, and optimize the use of water. Rapid degradation and turnover of proteins is required for effective nutrient recycling. Here, we examined the transcriptional responses of the C1A cysteine protease family to drought in barley and found that four genes were up-regulated in stressed plants. Knock-down lines for the protease-encoding genes HvPap-1 and HvPap-19 showed unexpected changes in leaf cuticle thickness and stomatal pore area. The efficiency of photosystem II and the total amount of proteins were almost unaltered in stressed transgenic plants while both parameters decreased in stressed wild-type plants. Although the patterns of proteolytic activities in the knock-down lines did not change, the amino acid accumulation increased in response to drought, concomitant with a higher ABA content. Whilst jasmonic acid (JA) and JA-Ile concentrations increased in stressed leaves of the wild-type and the HvPap-1 knock-down lines, their levels were lower in the HvPap-19 knock-down lines, suggesting the involvement of a specific hormone interaction in the process. Our data indicate that the changes in leaf cuticle thickness and stomatal pore area had advantageous effects on leaf defense against fungal infection and mite feeding mediated by Magnaporthe oryzae and Tetranychus urticae, respectively.

Effects of Shape and Orientation of Pore Canals on Mechanical Behaviors of Lobster Cuticles.

The work is to investigate the relationships between the microstructures and mechanical behaviors of lobster cuticles and reveal the inner mechanisms of the anisotropic mechanical properties of the cuticles and give the helpful guidance for the design of high-performance man-made composites. First, the tensile mechanical properties of the longitudinal and transverse specimens of the cuticles of American lobsters were tested with a mechanical-testing instrument. It is was found that the fracture strength and elastic modulus of the longitudinal specimens are distinctly larger than those of the transverse specimens. Then, the microstructural characteristics of the fracture surfaces of the specimens were observed with scanning electron microscope. It was observed that the pore canals in the cuticles are elliptic and their orientations are along the longitudinal orientation of the cuticles. Furthermore, the stresses and micro-damage of the longitudinal and transverse specimens were calculated with the rule of progressive damage by finite element method. It was revealed that the shape and orientation of the pore canals in the cuticles give rise to the anisotropic mechanical property of the cuticles and ensure that the cuticles possess the largest fracture strength and elastic modulus along their largest main-stress orientation.

Plant cuticles repress organ initiation and development during skotomorphogenesis in Arabidopsis.

After germination in the dark, plants produce a shoot apical hook and closed cotyledons to protect the quiescent shoot apical meristem (SAM), which is critical for seedling survival during skotomorphogenesis. The factors that coordinate these processes, particularly SAM repression, remain enigmatic. Plant cuticles, multilayered structures of lipid components on the outermost surface of the aerial epidermis of all land plants, provide protection against desiccation and external environmental stresses. Whether and how cuticles regulate plant development are still unclear. Here, we demonstrate that mutants of BODYGUARD1 (BDG1) and long-chain acyl-CoA synthetase2 (LACS2), key genes involved in cutin biosynthesis, produce a short hypocotyl with an opened apical hook and cotyledons in which the SAM is activated during skotomorphogenesis. Light signaling represses expression of BDG1 and LACS2, as well as cutin biosynthesis. Transcriptome analysis revealed that cuticles are critical for skotomorphogenesis, particularly for the development and function of chloroplasts. Genetic and molecular analyses showed that decreased HOOKLESS1 expression results in apical hook opening in the mutants. When hypoxia-induced expression of LITTLE ZIPPER2 at the SAM promotes organ initiation in the mutants, the de-repressed expression of cell-cycle genes and the cytokinin response induce the growth of true leaves. Our results reveal previously unrecognized developmental functions of the plant cuticle during skotomorphogenesis and demonstrate a mechanism by which light initiates photomorphogenesis through dynamic regulation of cuticle synthesis to induce coordinated and systemic changes in organ development and growth during the skotomorphogenesis-to-photomorphogenesis transition.

Lignocellulosic Membranes Grafted with N-Vinylcaprolactam Using Radiation Chemistry: Load and Release Capacity of Vancomycin.

Radiation chemistry presents a unique avenue for developing innovative polymeric materials with desirable properties, eliminating the need for chemical initiators, which can be potentially detrimental, especially in sensitive sectors like medicine. In this investigation, we employed a radiation-induced graft polymerization process with N-vinylcaprolactam (NVCL) to modify lignocellulosic membranes derived from Agave salmiana, commonly known as maguey. The membranes underwent thorough characterization employing diverse techniques, including contact angle measurement, degree of swelling, scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier-transform infrared-attenuated total reflectance spectroscopy (FTIR-ATR), nuclear magnetic resonance (CP-MAS 13C-NMR), X-ray photoelectron spectroscopy (XPS), and uniaxial tensile mechanical tests. The membranes' ability to load and release an antimicrobial glycopeptide drug was assessed, revealing significant enhancements in both drug loading and sustained release. The grafting of PNVCL contributed to prolonged sustained release by decreasing the drug release rate at temperatures above the LCST. The release profiles were analyzed using the Higuchi, Peppas-Sahlin, and Korsmeyer-Peppas models, suggesting a Fickian transport mechanism as indicated by the Korsmeyer-Peppas model.

Outer and internal cuticle in the leaves of Malus (Rosaceae) in mountains and plains.

The outer and internal cuticles in apple (Malus domestica Borkh.) leaves on the plain and in the mountains was studied using transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM). The outer cuticle consisted of lamellate and homogeneous layers of the cuticle proper and cuticular layer containing electron-transparent plates and electron-dense dendrites. Blue fluorescence predominated in the cell wall. The cuticle fluoresced green and red. The intensity of the red part of the spectrum in the cuticle increased with altitude, and the number of electron-transparent plates increased within the cuticular layer. The cell wall on both leaf sides was the thinnest in the arid conditions (300 m). At an altitude of 600 m, under favorable temperature and rainfall conditions, the cuticle thickness increased due to the cuticular layer adjacent to the cell wall. The internal cuticle was distinguished by intense yellow or red autofluorescence, similar in color and spectrum to the outer cuticle. The outer and internal cuticles had cuticular folds. The average distance between the ridges of the internal cuticle was almost the same in the samples at different altitudes. The ridge height was maximum at 600 m. RESEARCH HIGHLIGHTS: The altitudinal effects on outer and internal cuticles in apple leaves were studied. In the forest-mountain zone, the cuticle thickness increased due to the cuticular layer adjacent to the cell wall. The cell wall was the thinnest in arid conditions.

Extraction, physicochemical characterization, and morphological properties of chitin and chitosan from cuticles of edible insects.

As an alternative, cuticles from edible insects was proposed as an unconventional but viable source of chitin and chitosan. The chitin present in the mealworm's (Tenebrio molitor) cuticles was obtained biotechnologically in one step of enzymatic deproteinization and after deacetylated. Differences in the physicochemical characteristics and the properties of the cuticles, chitin, and chitosan were investigated in this study. Commercial chitosan was used as a reference sample to validate the methods used. The enzymatic deproteinization used to obtain chitin showed an efficiency of 85%. The global yield of the process (cuticle-to-chitosan) was 31.9%. The characterization results of these polymers using DSC, FT-IR, XRD, TGA, and SEM techniques demonstrate consistency with the degree of deacetylation of the obtained chitosan, allowing the differentiation between chitin and chitosan. This study suggests that the wastes of edible insect breeding should be collected and evaluated as an alternative of chitin/chitosan source.

Mechanical Performances of Isolated Cuticles Along Tomato Fruit Growth and Ripening.

The cuticle is the most external layer that protects fruits from the environment and constitutes the first shield against physical impacts. The preservation of its mechanical integrity is essential to avoid the access to epidermal cell walls and to prevent mass loss and damage that affect the commercial quality of fruits. The rheology of the cuticle is also very important to respond to the size modification along fruit growth and to regulate the diffusion of molecules from and toward the atmosphere. The mechanical performance of cuticles is regulated by the amount and assembly of its components (mainly cutin, polysaccharides, and waxes). In tomato fruit cuticles, phenolics, a minor cuticle component, have been found to have a strong influence on their mechanical behavior. To fully characterize the biomechanics of tomato fruit cuticle, transient creep, uniaxial tests, and multi strain dynamic mechanical analysis (DMA) measurements have been carried out. Two well-differentiated stages have been identified. At early stages of growth, characterized by a low phenolic content, the cuticle displays a soft elastic behavior. Upon increased phenolic accumulation during ripening, a progressive stiffening is observed. The increment of viscoelasticity in ripe fruit cuticles has also been associated with the presence of these compounds. The transition from the soft elastic to the more rigid viscoelastic regime can be explained by the cooperative association of phenolics with both the cutin and the polysaccharide fractions.

Building a Barrier: The Influence of Different Wax Fractions on the Water Transpiration Barrier of Leaf Cuticles.

Waxes are critical in limiting non-stomatal water loss in higher terrestrial plants by making up the limiting barrier for water diffusion across cuticles. Using a differential extraction protocol, we investigated the influence of various wax fractions on the cuticular transpiration barrier. Triterpenoids (TRPs) and very long-chain aliphatics (VLCAs) were selectively extracted from isolated adaxial leaf cuticles using methanol (MeOH) followed by chloroform (TCM). The water permeabilities of the native and the solvent-treated cuticles were measured gravimetrically. Seven plant species (Camellia sinensis, Ficus elastica, Hedera helix, Ilex aquifolium, Nerium oleander, Vinca minor, and Zamioculcas zamiifolia) with highly varying wax compositions ranging from nearly pure VLCA- to TRP-dominated waxes were selected. After TRP removal with MeOH, water permeability did not or only slightly increase. The subsequent VLCA extraction with TCM led to increases in cuticular water permeabilities by up to two orders of magnitude. These effects were consistent across all species investigated, providing direct evidence that the cuticular transpiration barrier is mainly composed of VLCA. In contrast, TRPs play no or only a minor role in controlling water loss.

Cutin from Solanum Myriacanthum Dunal and Solanum Aculeatissimum Jacq. as a Potential Raw Material for Biopolymers.

Plant cuticles have attracted attention because they can be used to produce hydrophobic films as models for novel biopolymers. Usually, cuticles are obtained from agroresidual waste. To find new renewable natural sources to design green and commercially available bioplastics, fruits of S. aculeatissimum and S. myriacanthum were analyzed. These fruits are not used for human or animal consumption, mainly because the fruit is composed of seeds. Fruit peels were object of enzymatic and chemical methods to get thick cutins in good yields (approximately 77% from dry weight), and they were studied by solid-state resonance techniques (CPMAS 13C NMR), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), atomic force microscopy (AFM) and direct injection electrospray ionization mass spectrometry (DIESI-MS) analytical methods. The main component of S. aculeatissimum cutin is 10,16-dihydroxypalmitic acid (10,16-DHPA, 69.84%), while S. myriacanthum cutin besides of 10,16-DHPA (44.02%); another two C18 monomers: 9,10,18-trihydroxy-octadecanoic acid (24.03%) and 18-hydroxy-9S,10R-epoxy-octadecanoic acid (9.36%) are present. The hydrolyzed cutins were used to produce films demonstrating that both cutins could be a potential raw material for different biopolymers.

Fractionation of plant-cuticle-based bio-oils by microwave-assisted methanolysis combined with hydrothermal pretreatment and enzymatic hydrolysis.

Microwave-assisted methanolysis was performed to fractionate a mixture of fatty acid methyl-esters from the cuticles of various wild plants and agricultural wastes. A combination of hydrothermal pretreatment and enzymatic hydrolysis effectively removed hemicellulose and cellulose to afford plant cuticles concentrated in residual materials. The subsequent methanolysis treatment afforded bio-oil from plant cuticles in ∼10% yield with a maximum higher heating value (HHV) of 32 MJ kg-1 from bagasse. The proposed cascading treatments allow the total use of herbaceous soft biomass by utilizing hemicellulose and cellulose fractions as well as plant cuticles to produce bio-oils with high HHVs.

Elements for optimizing a one-step enzymatic bio-refinery process of shrimp cuticles: Focus on enzymatic proteolysis screening.

This article complements an earlier work published in 2015 Baron et al. (2015) that showed the interest of a shrimp shells bio-refining process. We compare here the effect of eleven commercial proteases at pH 3.5 or 4.0 on a residual amount of shrimp shells proteins after 6 h at 50 °C. The two pH are obtained when respectively 40 and 25 mmol of formic acid are added to 5 g of mild dried shell. Deproteinisation yield above 95% are obtained. Residual amino acids profile in the solid phase was identical for the eleven proteases except for pepsin which was similar to the raw material profile. A significant relative increase in the proportion of Glycine is observed for the ten other cases. Likewise, shapes of size exclusion chromatograms of the dissolved phase are similar except with pepsin.

Comparative studies of cutins from lime (Citrus aurantifolia) and grapefruit (Citrus paradisi) after TFA hydrolysis.

Grapefruit and lime cutins were analyzed and compared in order to obtain information about their cutin architecture. This was performed using a sequential hydrolysis, first with trifluoroacetic acid to remove most of the polysaccharides present in the cutins, followed by an alkaline hydrolysis in order to obtain the main aliphatic compounds. Analysis by CPMAS 13C NMR and ATR FT-IR of the cutins after 2.0 M TFA revealed that grapefruit cutin has independent aliphatic and polysaccharide domains while in the lime cutin these components could be homogeneously distributed. These observations were in agreement with an AFM analysis of the cutins obtained in the hydrolysis reactions. The main aliphatic compounds were detected and characterized as 16-hydroxy-10-oxo-hexadecanoic acid and 10,16-dihydroxyhexadecanoic acid. These were present in grapefruit cutin at 35.80% and 21.86% and in lime cutin at 20.44% and 40.36% respectively.

Mind the Microgap in Iridescent Cellulose Nanocrystal Films.

A new photonic structure is produced from cellulose nanocrystal iridescent films reflecting both right and left circularly polarized light. Micrometer-scale planar gaps perpendicular to the films' cross-section between two different left-handed films' cholesteric domains are impregnated with a nematic liquid crystal. This photonic feature is reversibly tuned by the application of an electric field or a temperature variation.

Two strategies by epiphytic orchids for maintaining water balance: thick cuticles in leaves and water storage in pseudobulbs.

Epiphytes are an important component of tropical and subtropical flora, and serve vital ecological functions in forest hydrology and nutrient fluxes. However, they often encounter water deficits because there is no direct contact between their roots and the soil. The strategies employed by epiphytes for maintaining water balance in relatively water-limited habitats are not completely understood. In the present study, we investigated the anatomical traits, water loss rates, and physiology of leaves and pseudobulbs of four Dendrobium species with different pseudobulb morphologies to understand the roles of leaf and pseudobulb in maintaining water balance of epiphytic orchids. Our results showed that two species (D. chrysotoxum and D. officinale), with lower rates of water loss, have thicker leaves and upper cuticles, but lower epidermal thickness and leaf dry mass per area. In contrast, the other two species (D. chrysanthum and D. crystallinum) with thinner cuticles and higher rates of water loss, have less tissue density and greater saturated water contents in their pseudobulbs. Therefore, our results indicate that these latter two species may resist drought by storing water in the pseudobulbs to compensate for their thin cuticles and rapid water loss through the leaves. Under the same laboratory conditions, excised pseudobulbs with attached leaves had lower rates of water loss when compared with samples comprising only excised leaves. This implies that epiphytic orchids utilize two different strategies for sustaining water balance: thick cuticles to conserve water in leaves and water storage in pseudobulbs. Our results also show that Dendrobium species with thin cuticles tend to have pseudobulbs with high water storage capacity that compensates for their faster rates of water loss. These outcomes contribute to our understanding of the adaptive water-use strategies in Dendrobium species, which is beneficial for the conservation and cultivation of epiphytic orchids.

Acetylation of cell wall is required for structural integrity of the leaf surface and exerts a global impact on plant stress responses.

The epidermis on leaves protects plants from pathogen invasion and provides a waterproof barrier. It consists of a layer of cells that is surrounded by thick cell walls, which are partially impregnated by highly hydrophobic cuticular components. We show that the Arabidopsis T-DNA insertion mutants of REDUCED WALL ACETYLATION 2 (rwa2), previously identified as having reduced O-acetylation of both pectins and hemicelluloses, exhibit pleiotrophic phenotype on the leaf surface. The cuticle layer appeared diffused and was significantly thicker and underneath cell wall layer was interspersed with electron-dense deposits. A large number of trichomes were collapsed and surface permeability of the leaves was enhanced in rwa2 as compared to the wild type. A massive reprogramming of the transcriptome was observed in rwa2 as compared to the wild type, including a coordinated up-regulation of genes involved in responses to abiotic stress, particularly detoxification of reactive oxygen species and defense against microbial pathogens (e.g., lipid transfer proteins, peroxidases). In accordance, peroxidase activities were found to be elevated in rwa2 as compared to the wild type. These results indicate that cell wall acetylation is essential for maintaining the structural integrity of leaf epidermis, and that reduction of cell wall acetylation leads to global stress responses in Arabidopsis.

Allergy to hypoallergenic nail polish: does this exist?

Abstract The main allergen responsible for contact dermatitis to nail polish is tosylamide-formaldehyde resin. The so-called hypoallergenic nail polishes are suposedly free of agents that commonly trigger reactions. The commercially available products and their compositions were studied. It was observed that most brands present at least one component capable of triggering the disease; therefore, allergic reaction may occur even when hypoallergenic polishes are used. There should be a proper investigation of the specific allergen through a patch test, because more than one component can cause an allergy, and we need to check the exact composition of each product.

Comparison of nail lacquer clobetasol efficacy at 0,05%, 1% and 8% in nail psoriasis treatment: prospective, controlled and randomized pilot study / Comparação da eficácia do clobetasol em esmalte 0,05%, 1% e 8% no tratamento da psoríase ungueal: estudo piloto, prospectivo, controlado e randomizado

BACKGROUND: Nail psoriasis may affect up to 90% of patients with psoriasis in the course of the disease throughout their lives and it is often a therapeutic challenge to dermatologists. Topical treatments described in the literature have demonstrated variable efficacy, and unsatisfactory results have been associated to inefficient penetration of the active ingredient into the nail plate and proximal nail fold. Recently the use of clobetasol on nail lacquer vehicle has been suggested, with satisfactory results and no side effects. OBJECTIVE: To determine the efficacy and safety of clobetasol in nail lacquer vehicle in three concentrations (0.05%, 1% and 8%) in patients with nail psoriasis. METHODS: Prospective, controlled, randomized pilot study in fifteen patients with nail bed and/or nail matrix psoriasis in both hands, subdivided into three groups: A(0.05% clobetasol nail lacquer), B(1% clobetasol nail lacquer) and C(8% clobetasol nail lacquer). All groups used clobetasol nail lacquer on the left hand and base coat nail lacquer as control on the right, twice a week for 16 weeks. Clinical evaluation was done by photographic records and the NAPSI score of both treated and control hands, as well as modified NAPSI score of the most affected nail of the treated hand. RESULTS: Group C showed a statistically relevant clinical response compared to the other groups, reflected in the improvement of clinical parameters, of treated hand NAPSI score, when compared to the control hand, and modified NAPSI score of the most affected nail in the treated hand. CONCLUSION: The 8% clobetasol nail lacquer was effective and safe, and it can be considered a good option of topical therapy in the treatment of nail psoriasis.

FUNDAMENTOS: A psoríase ungueal, de difícil manejo terapêutico, pode afetar até 90% dos portadores de psoríase no transcurso da doença, ao longo de suas vidas. Os tratamentos tópicos descritos na literatura têm eficácia variável, muitas vezes com resultados insatisfatórios causados pela ineficiência da penetração da substância ativa através da placa ungueal e dobra proximal. Recentemente tem sido proposto o uso do clobetasol em veículo esmalte, demonstrando resultados satisfatórios e ausência de efeitos colaterais. OBJETIVO: Determinar a eficácia e segurança do clobetasol em veículo esmalte em três concentrações (0,05%, 1% e 8%) nos pacientes com psoríase ungueal. MÉTODOS: Estudo piloto, prospectivo, controlado e randomizado com quinze pacientes portadores de psoríase ungueal em ambas as mãos. Os pacientes foram subdivididos em três grupos: A (esmalte clobetasol 0,05%), B (esmalte de clobetasol 1%) e C (esmalte de clobetasol 8%). Os pacientes usaram esmalte de clobetasol na mão esquerda e esmalte base (sem medicação - controle) na direita, aplicandoos duas vezes por semana, por 16 semanas. Fez-se a avaliação clínica por registros fotográficos e pelos MÉTODOS: NAPSI da mão tratada e controle e NAPSI modificado da unha mais acometida da mão tratada. RESULTADOS: O grupo C apresentou de forma estatisticamente significativa a resposta clínica mais relevante, refletida na melhora dos parâmetros clínicos, do NAPSI da mão tratada comparado ao da mão controle e do NAPSI modificado da unha mais acometida da mão tratada. CONCLUSÕES: Neste estudo piloto, o esmalte de clobetasol a 8% foi eficaz e seguro, mostrando-se uma boa opção de terapêutica tópica no tratamento da psoríase ungueal.