Epidermal Surface Research Articles

Benign Cutaneous Tumors

Tumors of the cutaneous surface may arise from the epidermis, dermis, or subcutaneous tissue or from any of the specialized cell types in the skin or its appendages. Broad categories include tumors derived from epithelial, melanocytic, or connective tissue structures. Within each location or cell type, lesions are classified as benign, malignant, or, in certain cases, premalignant. Benign epithelial tumors include tumors of the surface epidermis that form keratin, tumors of the epidermal appendages, and cysts of the skin. Melanocytic (pigment-forming) lesions are very common. One of the most frequently encountered forms is the nevus cell nevus. Tumors that are derived from connective tissue include fibromas, histiocytomas, lipomas, leiomyomas, and hemangiomas. This chapter provides an overview of each type of tumor, including sections on epithelial tumors, tumors of the epidermal appendages, familial tumor syndromes, melanocytic tumors, neural tumors, connective tissue tumors, vascular birthmarks, acquired vascular disorders, Kimura disease, lipoma, leiomyoma, and lymphangioma circumscriptum. The sections discuss various forms and their diagnosis, differential diagnosis, and treatment. Figures accompany the descriptions. This chapter contains 83 references, 26 highly rendered figures, and 5 MCQs.

A CYP380C10 gene is required for waterproofing and water retention in the insect integument

Cuticular hydrocarbons (CHCs) are important components in the integument of insects and are required for development and survival. Insect-specific CYP4G subfamily, of the P450 enzymes, catalyze the oxidative decarbonylation step in the biosynthesis of CHCs. Here, we characterized CYP380C10 gene function in a Hemiptera rice pest, Nilaparvata lugens. We used RNA interference–mediated expression silencing to reveal that NlCYP380C10 played a key role in waterproofing and water–retention in the integument of N. lugens. Knockdown of NlCYP380C10 significantly reduced body weight and caused mortality. Scanning electron microscopy showed the loss of the lipid layer on the surface of the abdominal cuticle of the dsNlCYP380C10-injected adults. Furthermore, CHC profile analysis revealed that NlCYP380C10 knockdown significantly decreased the amounts of CHCs in adult females. This suggested that NlCYP380C10 was involved in CHC biosynthesis. Reduction of CHC content caused the loss of the intact lipid layer of the cuticle, which resulted in loss of the waterproofing and water-retention functions. This led to failure of molting and eclosion. Our findings expanded the knowledge of CHC biosynthesis in the insect integument and led to a better understanding of the functional roles of CYP450 genes involved in waterproofing and water–retention in insects.

Bacterial anti-adhesive films of PDMS coated with microstructures of biogenic silica rosettes extracted from pineapple peels residues

The appearance of several multi-drug resistant strains has been linked to the extensive use of antibiotics. The use of bio-inspired plant and animal surfaces that exhibit new strategies such as contact-killing surfaces has been proposed to face this problem. Pineapple peels expose 10 µm in length and 5 µm height biogenic silica rosettes (BSR) on their cuticle surface. These BSRs are formed by granules with sized of about 300 nm, which improve their mechanical properties and responses against stresses such as microorganisms' attacks. This study presents a valuable application of pineapple peel BSRs, becoming an attractive raw material for generating products with economic value such as coatings against non-specific adhesion of cells and bacteria on polydimethylsiloxane. Characterization techniques such as scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), and water contact angle were used. We found that the high-density coverage coating formed by BSR increased the PDMS roughness and surface's water repellency while decreasing the Escherichia coli (E. coli) bacteria adhesion. Besides, the cell membrane disruption effect on red blood cells was investigated. Inspired also by the cuticle of pineapple plants formed by lipids and waxes, we further functionalized the BSR with octadecyltrietoxysilane with the aim of increasing the hydrophobicity of the areas between the BSR voids and BSR surface. Bacteria adhesion decreased from 27% to 14% and an increased in contact angle from 130° to 158°. This coating has other potential uses, such as serving as a platform for encapsulating active compounds due to its high porosity. Therefore, different BSR arrangements could be studied to improve its antifouling properties.

CPR Gene Contributes to Integument Function and Ovary Development in a Rice Planthopper.

Nicotinamide adenine dinucleotide phosphate (NADPH)-cytochrome P450 reductase (CPR) is an essential enzyme that transfers electrons from NADPH to cytochrome P450 monooxygenases. CPR is involved in cuticular hydrocarbon (CHC) synthesis in insects and is vital for insect development and survival. Here, we clarify the physiological function of a CPR gene in Nilaparvata lugens, an important rice pest, by using RNA interference. CPR gene knockdown leads to the functional loss of waterproofing and water retention in the integument of female adults, which causes significantly reduced body weight and a lethal phenotype. Scanning electron microscopy shows that the lipid layer on the outermost surface of the abdominal cuticle becomes thin in dsCPR-injected adults. Furthermore, CHC profile analysis reveals that CPR knockdown significantly decreases the contents of CHCs with a carbon chain length ≥ C27 in adult females. Moreover, we find that CPR knockdown generates a deficient phenotype in ovaries with deformed oocytes and a complete failure of egg-laying. These findings suggest that CPR plays multiple functional roles in CHC biosynthesis and embryo development in insects.

The effectiveness of green tea and sonophoresis on oily skin: a case report

Background: Oily skin can be extremely problematic for sufferersand presents a great challenge for cosmetologists. This condition is characterized by an excessive amount of sebum on epidermal surface and enlarged skin pores.Modern cosmetology is able to offer a wide range of treatments that are able to reduce excess sebum secretion, and an appropriate diagnosis and cosmetic interview will allow for the selection of a suitable cosmetic treatment. If there are no contraindications for device treatments and the client is not allergic to cosmetic products, an ultrasound treatment called sonophoresis may be used. Green tea is obtained from both the leaves and buds of the Camellia sinensis plant. The active ingredients of green tea are polyphenols, which have antimicrobial, anti-inflammatory, and antineoplastic properties. Thanks to modern cosmetic devices, we are able to use green tea and sonophoresis to introduce this preparation into the skin. Aim of the study: The aim of this study was to evaluate the effectiveness of a sonophoresis treatment on oily skin in a 20-year-old female. Case report:The participant reported issues with too much sebum on the epidermis. The sebum level was measured before and after a series ofsonophoresistreatments using a sebumeter (DermaUnitSCC3). For the treatment, an ultrasound device and a cosmetic ampoule containing green tea extract were used. The entire cosmetic procedure consisted of 4 treatments performed at weekly intervals. Conclusions: After the series of cosmetological treatments, there was a significant reduction in sebum secretion.Thus, the use ofsonophoresis and a green tea ampoule turned out to be a great help in reducing epidermal sebum. The participant also noticed that her skin had less sheenfollowing the series of treatments.The resultsindicate that the sonophoresis procedure is safe and effective.

Functional leaf anatomy of the invasive weed Solanum rostratum Dunal

AbstractSolanum rostratum Dunal is an aggressive invasive weed invading many countries worldwide. Our previous study indicated differences in herbicide response between young and mature plants. In this study, we explore the functional leaf surface anatomy of S. rostratum. Leaf area surface characterisation was performed by counting stomata, stellate and glandular trichomes on upper and lower leaf sides on scanning electron microscopy (SEM) micrographs. Total cuticular waxes were extracted and weighed in young and mature leaves. Young and mature leaves were tested for water permeability of the epidermal surfaces using the apoplastic tracer Calcofluor. S. rostratum plants were sprayed with luminous trace colour solution with and without 1% surfactant, droplet number and area were calculated. In young S. rostratum leaves, the leaf surface was densely covered with stellate trichomes on both leaf sides; however, in the mature leaf, stellate trichomes density became low, and prickle rigid increased in mature leaves. Wax amount was significantly higher in mature leaves, while number of stomata was higher in young leaves. Young leaves showed high leaf permeability, with the fluorescent dye permeating the leaf staining the vascular bundles. In young and mature leaves treated with a spraying solution with the addition of surfactant, low droplet number alongside higher coverage area was recorded. Our data highlight the notable differences in leaf epidermal structure of young versus mature plants. We conclude that differences in herbicide permeability, water loss and herbivory in young versus mature leaves of S. rostratum are governed by variation in leaf functional anatomy.

Secretory Products in Petals of Centaurea cyanus L. Flowers: A Histochemistry, Ultrastructure, and Phytochemical Study of Volatile Compounds.

(1) Background: Centaurea cyanus L. is a medicinal plant whose flowers are widely used in herbal medicine. The aim of the study was to localise flower tissues that are responsible for the production of secretory products in petals and to analyse the volatile compounds. The volatile compounds of the flowers of this species have not been investigated to date. (2) Methods: Light, fluorescence, scanning and transmission electron microscopy techniques were used in the study. Lipophilic compounds were localised in the tissues using histochemical assays. Volatile compounds were determined with the use of solid phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS). (3) Results: The study showed production of secretion in the petal parenchyma, whose ultrastructure has features of a secretory tissue. The lipophilic secretion was localised in the cells and intercellular spaces of the parenchyma and in the walls and surface of epidermal cells, where it accumulated after release through cuticle microchannels. Sesquiterpenes were found to constitute the main group of volatile compounds, with the highest content of β-caryophyllene (26.17%) and α-humulene (9.77%). (4) Conclusions: Given the presence of some volatile components that are often found in resins (caryophyllene, delta-cadinene) and the abundant secretion residues on the epidermal surface, we suppose that the C. cyanus secretion released by the flowers is a resinaceous mixture (oleoresin), which is frequently found in plants, as shown by literature data. This secretion may play an important role in the therapeutic effects of C. cyanus flowers.

Onion inspired hydrate-phobic surfaces

Hydrate plugging in gas- and oil-production and transport systems has long been a critical challenge. Traditional hydrate mitigation strategies through applying chemicals and thermal destabilization are costly and eco-unfriendly. Passive anti-hydrate surfaces with potential to enable self-removal of hydrates are desired. Surprisingly, thin onion film peeled off from an onion bulb scale is found to have low hydrate adhesion, thanks to the porous structures and the surface cuticle layer. Subsequently, through mimicking the bio-properties of an actual onion film, a hydrate-phobic onion inspired surface with super low hydrate adhesion strength is fabricated. By engineering abundant pores below smooth surface, the onion inspired surface dramatically decreases the cyclopentane (CyC5) hydrate adhesion strength from 95 kPa to 4.7 kPa. The onion inspired surface also maintains super low hydrate adhesion (8.7 kPa) after 20 hydrating/de-hydrating cycles. Furthermore, the performance of this new hydrate-phobic surface is enhanced by integrating a regenerable artificial cuticle layer, which enables even lower hydrate adhesion (2.9 kPa). Therefore, the onion inspired surface can provide alternative solutions for future hydrate mitigation.

Antibiofilm Effect of Curcumin Against Staphylococcus aureus Surface Wound Biofilm-Associated Infection: In Vitro and In Silico.

Biofilm is the consortia of the sessile group of microbial species that are adhered to the biotic and abiotic surfaces with the help of extracellular polymeric substances (EPS) and glycocalyx. A wound is a lesion on the epidermal surface that exposes the underlying tissues to the external environment and thus forms a region of proliferation for several species of Staphylococcus aureus. S. aureus is the most commonly observed nosocomial biofilm-forming organism that is responsible for the development of wound-associated infections. The biofilm prevents the penetration of the drug molecules thereby resulting in the development of antibiotic and multi-drug resistance among the organism. Thus, the use of alternative therapeutics has paved the path in the treatment of biofilm-associated infections. Curcumin has been used for the purpose of treating various illnesses from time immemorial. In this study, we observed that curcumin was able to bring about a reduction in the biofilm formed by S. aureus in the wound infection among the patients. The in silico studies revealed that curcumin possessed the ability to bring about interaction with the biofilm-forming proteins of S. aureus effectively.

Histology and Vascular Architecture Study of Keloid Tissue to Outline the Possible Terminology of Keloid Skin Flaps.

Using the keloid "epidermis" to cover a wound is widely used during treatment for keloids. Many flap terminologies have been used in literature. However, the definition of the flap is not well established. Here, we refined the definition of the flap and associated terminology and explored the survival mechanism of the 'flap' through histological analysis and blood supply studying. Histology and vascular study of keloid was carried out with keloid and its surrounding normal skin tissue which were collected from keloid patients following keloid resection operations. The histological structures and thicknesses of epidermal and subepidermal of the keloids were analyzed and measured using hematoxylin & eosin (H&E) staining. Vascular density and blood perfusion in the subepidermal layer of keloids (KDS) were analyzed using CD31 immunohistochemical staining and a laser speckle contrast imaging system (LSCI), respectively. The vascular network in KDS was visualized by CD31 immunofluorescence staining and three-dimensional reconstruction. 29 pieces of keloid and its surrounding normal skin tissue sample from ten patients were collected. Keloid samples were about 2 cm wide and 5 cm long. The normal skin samples were about 2 to 3 mm in width. The thickness of epidermal layer of keloids was (136.4 ± 35.3) μm, and the thickness of epidermal layer of surrounding normal skin was (78.8 ± 13.9) μm. There was statistical thickness difference between the two layers, t(20) = 7.469, P < 0.001. The total thickness of keloid epidermal and subepidermal layers was 391.4 ± 2.3 μm. The vascular density (13.9 ± 3.4/field) and blood flow perfusion (132.7 ± 31.3) PU in KDS were greater than that of surrounding normal skin (7.8 ± 2.3/field, 73.9 ± 17.9 PU), P < 0.001. Horizontally distributed vessels with several vertical branches were observed in 3D vascular network reconstruction. The epidermal layer of keloid is thicker than that of surrounding normal skin. There is a vascular network structure under it. The vessels mainly locate at a depth of about 150 to 400 μm from the surface of keloid epidermis, randomly distribute and run parallel to the epidermis. Based on these characteristics which may ensure an adequate blood supply, we propose the concept of a "keloid subepidermal vascular network flap." This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

ECM degradation in the Drosophila abdominal epidermis initiates tissue growth that ceases with rapid cell-cycle exit

SummaryDuring development, multicellular organisms undergo stereotypical patterns of tissue growth in space and time. How developmental growth is orchestrated remains unclear, largely due to the difficulty of observing and quantitating this process in a living organism. Drosophila histoblast nests are small clusters of progenitor epithelial cells that undergo extensive growth to give rise to the adult abdominal epidermis and are amenable to live imaging. Our quantitative analysis of histoblast proliferation and tissue mechanics reveals that tissue growth is driven by cell divisions initiated through basal extracellular matrix degradation by matrix metalloproteases secreted by the neighboring larval epidermal cells. Laser ablations and computational simulations show that tissue mechanical tension does not decrease as the histoblasts fill the abdominal epidermal surface. During tissue growth, the histoblasts display oscillatory cell division rates until growth termination occurs through the rapid emergence of G0/G1 arrested cells, rather than a gradual increase in cell-cycle time as observed in other systems such as the Drosophila wing and mouse postnatal epidermis. Different developing tissues can therefore achieve their final size using distinct growth termination strategies. Thus, adult abdominal epidermal development is characterized by changes in the tissue microenvironment and a rapid exit from the cell cycle.

Annona (Annonaceae) by-products derivatives: Toxicity to the European pepper moth and histological assessment

Obtaining derivatives with insecticidal properties from abundant plant biomass (waste) represents a good opportunity to transform environmental problems into innovative solutions for pest management programs. In the present study, we evaluated the toxicity of the aqueous emulsions of the ethanolic extract of Annona mucosa and Annona sylvatica (Annonaceae) seeds on the European pepper moth Duponchelia fovealis (Lepidoptera: Crambidae), a major pest of strawberry plants. In addition, we evaluated anti-feeding and developmental inhibitory effects, as well as macro and microscopic damage to the excretory and nervous systems of European pepper moth larvae. In the contact bioassay, the aqueous emulsion of A. mucosa extract provided the fastest action on larvae with LT50 of 6.10 h, followed by chlorfenapyr (Pirate®) (LT50 = 8.2 h) and the aqueous emulsion of the A. sylvatica extract (LT50 = 10.3 h). In contrast, the commercial bioinsecticide based on acetogenins (Anosom® 1 EC) had a higher LT50 (32.8 h). In addition to the lethal effects, the aqueous emulsions tested caused significant phagodeterrence (>90%) and inhibited the development of D. fovealis. Macroscopic observation revealed the presence of edemas as well as the darkening on the surface of the larvae's cuticle. Histological analyses detected alterations. Our results suggest that aqueous emulsions produced from ethanolic extract of A. mucosa and A. sylvatica seeds, a residue in fruit processing industrial complexes (pulp factories), are alternatives for the management of D. fovealis, especially in organic and/or ecological strawberry production systems.

Leaf anatomy of Eriocaulon (Eriocaulaceae, Poales) species reveals a correlation between life form, anatomical features and life cycle

The study presents leaf anatomy of 30 species of Eriocaulon (Eriocaulaceae) from India and Brazil. Observations of the anatomical traits and multivariate analyses were carried out to investigate the correlation between life cycle, life form, and leaf anatomical features of Eriocaulon species. The leaf anatomical characters of amphibian and submerged species were more consistent compared to those of emergent species. Features linked to amphibian form were non-sinuous outline with parallel adaxial and abaxial epidermal surfaces, dissimilar adaxial versus abaxial epidermal layers, acuminate leaf margins, interrupted subepidermal chlorenchyma, compactly arranged mesophyll diaphragm layers, well-developed bundles equidistant to both epidermal surfaces, and both adaxial and abaxial sheath extensions. The consistent features of the submerged species were continuous subepidermal chlorenchyma, poorly developed, vascular bundles directly below the subepidermal chlorenchyma with abaxial sheath extensions only, and similar adaxial and abaxial epidermal layers. However, emergent life form species did not show a consistent pattern. The Indian emergent species exhibited different combinations of the characters from the two other life forms, whilst the Brazilian emergent life forms were quite similar to the submerged species. The rheophytic life form showed a good degree of reduction in aerenchyma in its leaves. It presented a dual anatomical pattern; the epidermal cells were conspicuously small and thick-walled in the upper portion, but large and with thinner walls at the basal region. Unusual characters were present as well, such as trichome tufts guarding the stomata in E. brownianum. Regarding the life cycle patterns, the perennial pattern showed a positive correlation with the submerged and, to some extent, amphibian life forms, whereas the annual pattern was better embodied in the emergent life form species.

Morpho-anatomical, biochemical and molecular genetic responses of canola (Brassica napus L.) to sulphur application

Brassica napus (canola), a major economic crop in Egypt, contains much oils and proteins. In the present study, the foliar applications of ammonium sulphate (A.S.) [(NH4)2SO4] (0, 1% 0.2% and 0.3%) to canola plants had distinctive impacts on the morpho-anatomical, biochemical, and molecular genetic responses. Interestingly, there is a positive impact when sulphur (S) is foliarly applied at 0.2% of A.S. as revealed in antioxidants, flavonoids, total carbohydrates, and protein contents which were significantly affected. On the other hand, higher levels of glucosinolates were recorded for 0.3% and 1% A.S. (4.838 and 1.905, respectively). The electrophoretic analysis of proteins displayed 51 bands of molecular weights ranging from 8.555 to 240.6 kDa with 88.24% polymorphism with a mean band frequency of 0.373. Cytotoxicity assay revealed that the lower cell death was detected in treated root tips of canola plants following 0.2% A.S. treatment, as compared to control. With increasing of sulphur treatment, the root cortex thickness, number of conducting elements, and pericycle thickness decreased while root pith area increased. In canola leaves of high S level, the leaf blade thickness, the thickness of abaxial and adaxial epidermis surface, mesophyll thickness, and metaxylem area increased, while the xylem conducting elements number decreased. Moreover, SCoT molecular markers have been used to evaluate the genetic variation among Brassica napus genotypes subjected to different A.S. treatments. Four of the seven SCoT primers were revealed to be polymorphic in both treated and untreated samples. A total of 39 amplicons, ranging in size from 200 to 1080 bp, were amplified, with 9 (23.07%) of them being polymorphic. Clustering dendogram based on SCot markers data divided Brassica genotypes into two main clusters based on similarity coefficients indices. B. napus treated with 0.2% A.S. was separated in a distinct cluster. Furthermore, treatments with sulphur enhanced the activity of antioxidant enzymes as well as the expression level of their encoding genes (CAT, catalase; POD, peroxidase; APX, ascorbate peroxidase; SOD, superoxide dismutase; GR, glutathione reductase), particularly at 1% and 0.2% A.S. treatments. Taken together, this study revealed that foliar application of sulphur treatments, particularly at 0.2%, have a great potential to improve canola crop.

A subpopulation of green turtle suprabasal epidermal cells are Langerin+ and migrate under in vitro stimulation of the chemokine CCL21.

Dendritic cells form the link between the innate and adaptative immune response, particularly on mucosal and epidermal surfaces. The Langerhans, an epidermal dendritic cell subpopulation, play a key role in the skin immune response across several species. Scarse immune cell subpopulations, including Langerhans-like cells, have been identified in endangered green turtles thereby complicating the understanding of the pathogenesis of diseases such as fibropapillomatosis, which induces skin tumours in this species worldwide. In biopsies from green turtle skin, we demonstrated that the polyclonal anti-human Langerin antibodies strongly stained a Langerin+ cell population in epidermal sheets, the suprabasal layer of the epidermis in cryosections and in cells from cytospin preparation of migration assays. The morphology of these cells was round to amoeboid in normal skin; however, in skin with ulcerative dermatitis, Langerin+ cells aggregated around ulcers and adopted a more pleomorphic morphology. To our knowledge, this is the first identification of Langerin+ cells with a molecular marker in a reptile species.

Chemical Profiling and Wetting Behaviors of Endemic Salvia absconditiflora Greuter &amp; Burdet (Lamiaceae) Collected from Gypsum Areas

Objective: Salvia absconditiflora Greuter &amp; Burdet is an endemic plant and survives in nature by adapting to extreme conditions. The aims of this study are to characterize and compare the diversity in the spectral-chemical structure of S. absconditiflora’s plant parts using the FTIR spectroscopy technique, to determine the wettability of the adaxial and abaxial epidermal surfaces of S. abscontidiflora leaves and to interpret whether there is a difference between the contact angle (CA) measurements at the points determined in the surface area of the leaves from the part close to the petiole to the leaf tip. Materials and Methods: The ATR-FTIR spectra for the chemical content of S. absconditiflora were obtained from six different plant parts and information about their chemical compositions was obtained. CA measurements were carried out for the natural events of the leaf area, especially for the water holding capacity or hydrophilic-hydrophobic characteristics. Results: The biochemical fingerprint of S. absconditiflora was determined by the analysis of chemical groups in vegetative and generative plant parts using ATR-FTIR spectroscopy. The CAs showed that the leaf had a hydrophobic character. In addition, leaf hysteresis was determined for each plant part, and it was understood that the lotus effect also appeared in S. absconditiflora. Conclusion: Detailed biochemical profiling, wettability, and hysteresis reports of S. absconditiflora were created for the first time. With this study, important clues about the adaptation of plants to harsh conditions were obtained.

Achene micromorphological character study of six Kyllinga spp. (Cyperaceae) from south India using scanning electron microscope (SEM) for its taxonomic significance

Scanning electron microscope (SEM) study was used to examine achene epidermal surface features to add additional taxonomic characters for classification and to solve identification problems in six Kyllinga species of South India that are deposited in the Madras Herbarium (MH). The present study reveals that, the presence and absence of silica body in each cell based on the epidermal features plays an important role to differentiate the distinct individuals. Previous investigations support the data of achene micromorphology like exocarp cell shape, anticlinal and periclinal walls of the epidermal cell obtained using SEM delimits the taxa.

Bioinspired Imbricated Microthorn Scale Surfaces and their Abrasive Wear Performance

HighlightsImproving the wear resistance of soil-engaging components is an urgent need for the agricultural machinery industry.Sandfish (Scincus scincus) epidermis with exceptional wear resistance was selected as a bionic prototype.By adopting a bionic engineering approach, a novel bioinspired microthorn scale surface was designed and prepared.Numerical simulations were performed with EDEM to investigate the wear resistance mechanism.Abstract. To solve the problem of abrasive wear failure of the soil-engaging components of agricultural machinery, the imbricated microthorn scale structure of the sandfish (Scincus scincus) epidermis surface was selected as a bionic prototype. By adopting a bionic engineering approach, nine bionic microthorn scale surface specimens with different geometric structure parameters were designed and prepared. Wear resistance tests were performed in a rotating abrasive wear testing system. The results of the wear tests showed that the imbricated microthorn scale structured surfaces had substantially less abrasion loss than a conventional smooth surface. The influence of the geometric structure parameters on the wear performance was also identified. Numerical simulations were performed to explore the wear resistance mechanism of the imbricated microthorn scale structured surfaces. The abrasion of the bionic surfaces mainly occurred at the edge of the microthorn that faced the abrasive particle flow. The trajectory of subsequent abrasive particle flow was modified by the large dispersion of particle flow; hence, the number of particles that impacted the surface decreased. Therefore, the wear resistance performance of the bionic surfaces was enhanced. This bioinspired surface can provide a technical reference to mitigate the abrasive wear failure of the soil-engaging components of agricultural machinery. Keywords: Abrasive wear, Archard wear, Bionic design, Discrete element method, Scale surface.

Agronomic, anatomic and physiological characterization of Coffea arabica L. genotypes on irrigated system in the Central Cerrado

Due to climatic conditions and the possibility of using machineries, coffee has a potential to achieve high yields with reduced costs, in the biome of Cerrado. Leaf anatomy and physiology can help in the identification of more adapted cultivars to a given environmental condition. The objective is to verify the behavior of Coffea arabica L. genotypes in the Cerrado of the Brazilian Central Plateau through anatomical and physiological characterization and yield. Ten coffee genotypes from the Active Germplasm Bank located in the municipality of Planaltina, Distrito Federal, were evaluated. The genotypes evaluated were: Araponga MG1, Catiguá MG2, Catiguá MG3 P23, Catiguá MG3 P7, Catiguá MG3 P51, Catiguá MG3 P, Catuaí Amarelo IAC 62, Catuaí Vermelho IAC 15, Paraíso MG1 and Topázio MG 1190. The phenotypic characteristics evaluated were the thickness of: adaxial cuticle surface, adaxial and abaxial epidermis surfaces, the palisade and spongy parenchyma, the mesophyll layer, the phloem, number and diameter of the xylem vessels, stomatal density,relationship between the polar and equatorial diameter of the stoma, specific leaf area, stomatal conductance, transpiration rate, net photosynthetic rate, water use efficiency, intercellular carbon concentration and yield. Genotypes of Coffea arabica L. presented a distinction between the characteristics evaluated when grown under climatic conditions of the Brazilian Central Plateau Cerrado, highlighting the variations in the behavior and distinguished adaptation in this environment. The Araponga MG1 genotype stood out for anatomical and physiological characteristics of higher values, such as net photosynthetic rate, stomatal conductance, intercellular carbon concentration, abaxial and adaxial epidermis thickness, stomatal density and number of xylem vessels. The genotype Paraíso MG1 stands out for higher grain productivity. The genotype Catuaí Vermelho IAC 15 stands out for anatomical and physiological characteristics such as higher stomatal density, greater number of xylem vessels and greater efficiency in water use, resulting in improved productivity.Key words: Adaptability; Coffee tree; Morphology; Grain yield; Gas exchange.

Dynamic regulation of human epidermal differentiation by adhesive and mechanical forces.

The interfollicular epidermis is the multilayered epithelium that forms the outer layer of the skin. It is maintained by stem cells that are attached to a basement membrane, which lies on top of the underlying connective tissue, the dermis. Cells undergo terminal differentiation as they detach from the basement membrane and move toward the outer epidermal surface. Over time, many of the molecular regulators of this process have been identified. It is now is clear that these pathways also receive critical input from the physical properties of the tissue. In this review, we describe how changes in these factors regulate differentiation and how new insights from single cell RNA sequencing could provide validation or challenge to the existing experimental models.