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Background and Aims Internal root aeration is essential for root growth in waterlogged conditions. Aerenchyma provides a path for oxygen to diffuse to the roots. In most wetland species, including rice, a barrier to radial oxygen loss (ROL) allows more of the oxygen to diffuse to the root tip, enabling root growth into anoxic soil. Most dryland crops, including barley, do not form a root ROL barrier. We previously found that abscisic acid (ABA) signalling is involved in the induction of ROL barrier formation in rice during waterlogging. Although rice typically does not form a tight ROL barrier in roots in aerated conditions, an ROL barrier with suberized exodermis was induced by application of exogenous ABA. Therefore, we hypothesized that ABA application could also trigger root ROL barrier formation with hypodermal suberization in barley. Methods Formation of an ROL barrier was examined in roots in different exogenous ABA concentrations and at different time points using cylindrical electrodes and Methylene Blue staining. Additionally, we evaluated root porosity and observed suberin and lignin modification. Suberin, lignin and Casparian strips in the cell walls were observed by histochemical staining. We also evaluated the permeability of the apoplast to a tracer. Key Results Application of ABA induced suberization and ROL barrier formation in the adventitious roots of barley. The hypodermis also formed lignin-containing Casparian strips and a barrier to the infiltration of an apoplastic tracer (periodic acid). However, ABA application did not affect root porosity. Conclusions Our results show that in artificial conditions, barley can induce the formation of ROL and apoplastic barriers in the outer part of roots if ABA is applied exogenously. The difference in ROL barrier inducibility between barley (an upland species) and rice (a wetland species) might be attributable to differences in ABA signalling in roots in response to waterlogging conditions. [ABSTRACT FROM AUTHOR]

T-cell recruitment to skin tissues is essential for inflammation in different cutaneous diseases; however, the mechanisms by which these T cells access the skin remain unclear. High endothelial venules expressing peripheral node address in (PNAd), an L-selectin ligand, are located in secondary lymphoid organs and are responsible for increasing T-cell influx into the lymphoid tissues. They are also found in non-lymphoid tissues during inflammation. However, their presence in different common inflammatory cutaneous diseases and their correlation with T-cell infiltration remain unclear. Herein, we explored the mechanisms underlying the access of T cells to the skin by investigating the presence of PNAd-expressing vessels in different cutaneous diseases, and its correlation with T cells' presence. Skin sections of 43 patients with different diseases were subjected to immunohistochemical and immunofluorescence staining to examine the presence of PNAd-expressing vessels in the dermis. The correlation of the percentage of these vessels in the dermis of these patients with the severity/grade of CD3+ T-cell infiltration was assessed. PNAd-expressing vessels were commonly found in the skin of patients with different inflammatory diseases. A high percentage of these vessels in the dermis was associated with increased severity of CD3+ T-cell infiltration (P < 0.05). Additionally, CD3+ T cells were found both around the PNAd-expressing vessels and within the vessel lumen. PNAd-expressing vessels in cutaneous inflammatory diseases, characterized by CD3+ T-cell infiltration, could be a crucial entry point for T cells into the skin. Thus, selective targeting of these vessels could be beneficial in cutaneous inflammatory disease treatment. In our study, we observed that PNAd-expressing vessels, identified as a crucial gateway for CD3+ T-cell entry into secondary lymph nodes, are a hallmark feature in the dermis across various CD3+ T-cell-mediated cutaneous diseases. This observation correlates with the extent of CD3+ T-cell infiltration within these conditions, suggesting that PNAd-expressing vessels may serve as a critical conduit for CD3+ T cells into the skin. Graphical Abstract [ABSTRACT FROM AUTHOR]

Objectives Our previous studies have demonstrated that the Damage Associated Molecular Pattern (DAMP) protein, S100A4, is overexpressed in the involved skin and peripheral blood of patients with SSc. It is associated with skin and lung involvement, and disease activity. By contrast, lack of S100A4 prevented the development of experimental dermal fibrosis. Herein we aimed to evaluate the effect of murine anti-S100A4 mAb 6B12 in the treatment of preestablished experimental dermal fibrosis. Methods The effects of 6B12 were assessed at therapeutic dosages in a modified bleomycin-induced dermal fibrosis mouse model by evaluating fibrotic (dermal thickness, proliferation of myofibroblasts, hydroxyproline content, phosphorylated Smad3-positive cell count) and inflammatory (leukocytes infiltrating the lesional skin, systemic levels of selected cytokines and chemokines) outcomes, and transcriptional profiling (RNA sequencing). Results Treatment with 7.5 mg/kg 6B12 attenuated and might even reduce pre-existing dermal fibrosis induced by bleomycin as evidenced by reduction in dermal thickness, myofibroblast count and collagen content. These antifibrotic effects were mediated by the downregulation of TGF-β/Smad signalling and partially by reducing the number of leukocytes infiltrating the lesional skin and decrease in the systemic levels of IL-1α, eotaxin, CCL2 and CCL5. Moreover, transcriptional profiling demonstrated that 7.5 mg/kg 6B12 also modulated several profibrotic and proinflammatory processes relevant to the pathogenesis of SSc. Conclusion Targeting S100A4 by the 6B12 mAb demonstrated potent antifibrotic and anti-inflammatory effects on bleomycin-induced dermal fibrosis and provided further evidence for the vital role of S100A4 in the pathophysiology of SSc. [ABSTRACT FROM AUTHOR]

The microtubule motor dynein is critical for the assembly and positioning of mitotic spindles. In Caenorhabditis elegans , these dynein functions have been extensively studied in the early embryo but remain poorly explored in other developmental contexts. Here, we use a hypomorphic dynein mutant to investigate the motor's contribution to asymmetric stem cell–like divisions in the larval epidermis. Live imaging of seam cell divisions that precede formation of the seam syncytium shows that mutant cells properly assemble but frequently misorient their spindle. Misoriented divisions misplace daughter cells from the seam cell row, generate anucleate compartments due to aberrant cytokinesis, and disrupt asymmetric cell fate inheritance. Consequently, the seam becomes disorganized and populated with extra cells that have lost seam identity, leading to fatal epidermal rupture. We show that dynein orients the spindle through the cortical GOA-1Gα–LIN-5NuMA pathway by directing the migration of prophase centrosomes along the anterior–posterior axis. Spindle misorientation in the dynein mutant can be partially rescued by elongating cells, implying that dynein-dependent force generation and cell shape jointly promote correct asymmetric division of epithelial stem cells. [ABSTRACT FROM AUTHOR]

The stem, consisting of nodes and internodes, is the shoot axis, which supports aboveground organs and connects them to roots. In contrast to other organs, developmental processes of the stem remain elusive, especially those initiating nodes and internodes. By introducing an intron into the Cre recombinase gene, we established a heat shock–inducible clonal analysis system in a single binary vector and applied it to the stem in the flag leaf phytomer of rice (Oryza sativa). With detailed characterizations of stem structure and development, we show that cell fate acquisition for each domain of the stem occurs stepwise. Cell fate for a single phytomer was established in the shoot apical meristem (SAM) by one plastochron before leaf initiation. Cells destined for the foot (nonelongating domain at the stem base) also started emerging before leaf initiation. Cell fate acquisition for the node began just before leaf initiation at the flank of the SAM, separating cell lineages for leaves and stems. Subsequently, cell fates for the axillary bud were established in early leaf primordia. Finally, cells committed to the internode emerged from, at most, a few cell tiers of the 12- to 25-cell stage stem epidermis. Thus, internode cell fate is established last during stem development. This study provides the groundwork to unveil underlying molecular mechanisms in stem development and a valuable tool for clonal analysis, which can be applied to various species. A heat shock–inducible clonal analysis system for rice revealed the temporal order of cell fate establishment of stem organs in the flag leaf phytomer. [ABSTRACT FROM AUTHOR]

The vasculature along conifer needles is fundamentally different from that in angiosperm leaves as it contains a unique transfusion tissue inside the bundle sheath. In this study, we used specific tracers to identify the pathway of photoassimilates from mesophyll to phloem, and the opposing pathway of nutrients from xylem to mesophyll. For symplasmic transport we applied esculin to the tip of attached pine needles and followed its movement down the phloem. For apoplasmic transport we let detached needles take up a membrane-impermeable contrast agent and used micro-X-ray computed tomography to map critical water exchange interfaces and domain borders. Microscopy and segmentation of the X-ray data enabled us to render and quantify the functional 3D structure of the water-filled apoplasm and the complementary symplasmic domain. The transfusion tracheid system formed a sponge-like apoplasmic domain that was blocked at the bundle sheath. Transfusion parenchyma cell chains bridged this domain as tortuous symplasmic pathways with strong local anisotropy which, as evidenced by the accumulation of esculin, pointed to the phloem flanks as the preferred phloem-loading path. Simple estimates supported a pivotal role of the bundle sheath, showing that a bidirectional movement of nutrient ions and assimilates is feasible and emphasizing the role of the bundle sheath in nutrient and assimilate exchange. [ABSTRACT FROM AUTHOR]

Eighty-eight of the 255 Diospyros species from Madagascar are potential sources of ebony wood. Unfortunately, several species are currently threatened with extinction due in part to illegal and unsustainable logging. Reliable identification of living Diospyros species is necessary prior to any sustainable exploitation, so as not to compromise those species threatened with extinction. This study aims to identify features that might contribute to supporting taxonomic studies and to provide a complementary tool for the identification of standing trees. Fifteen species of Diospyros endemic to Madagascar were studied using standard anatomical methods. Each species showed a different shape of the leaf midrib and some have distinctive leaf anatomical characteristics, such as the presence of extrafloral nectaries in the distal part of the petiole in Diospyros baronii and filiform sclerenchyma in the mesophyll in Diospyros lewisiae. Statistical analysis showed that petiole and midrib vascular patterns, spongy parenchyma structure, the presence of papillae, thickness of epidermis, presence of extrafloral nectaries, stratification of epidermis, and presence of a cuticle are useful to distinguish species groups and even some species. The anatomy of young stems and leaves of Diospyros species from Madagascar is examined for the first time; the study will be extended to other potentially exploitable species. [ABSTRACT FROM AUTHOR]

Fish skin is mainly composed of the epidermis, dermis, and its derivative scales. There is a wide diversity in scale number in fishes, but the diversity of skin structure lacks systematic histological comparison. This research aimed to improve our understanding of the functional relationship between the scale number and the skin structure in freshwater fishes and to determine which ecological factors affect the scale number and skin structure. First, we presented a method to quantify skin structure in fish and histologically quantified the skin structure of 54 freshwater fishes. Second, we collected the scale number and habitat information of 509 Cyprinidae fishes in China and explored which ecological factors were related to their scale number. Third, common carp and scaleless carp were used as models to study the effects of scale loss on swimming. We found a strong negative correlation between scale thickness and scale number. The main factor affecting the skin structure of fishes was the species' water column position, and the skin of benthic fishes was the most well-developed (thicker skin layers (dermis, epidermis) or more/larger goblet cells and club cells). The scale number was related to two factors, namely, temperature and water column position, and cold, benthic and pelagic adaptation may have contributed to increased scale numbers. Only in benthic fishes, the more well-developed their skin, the more scales. In common carp, scale loss did not affect its swimming performance. In summary, we suggest that there is a rich diversity of skin structure in freshwater fishes, and the scales of fish with well-developed skin tend to degenerate (greater number/smaller size/thinner, or even disappear), but the skin of fish with degenerated scales is not necessarily well developed. [ABSTRACT FROM AUTHOR]

Dermatofibrosarcoma Protuberans (DFSP) is a rare, locally aggressive fibroblastic mesenchymal neoplasm, typically derived from the dermis, with the intramammary subtype being seen infrequently. We present a case of a 40-year-old woman whom was diagnosed with an intramammary DFSP during pregnancy, whom underwent successful surgical management during her second trimester. Our case demonstrates the importance of increased clinical awareness in the diagnosis and treatment of breast DFSP with careful multidisciplinary consideration. [ABSTRACT FROM AUTHOR]

A 56-year-old woman presented with abdominal, lumbar and thoracic livedo with 2 years of evolution, consisting of violaceous poikilodermatous patches with scattered petechiae on a base of erythema and telangiectasia, accompanied by diffuse and mild skin atrophy. Histological analysis revealed vasodilation of the superficial dermis and thickening of capillary walls, highlighted by periodic acid–Schiff stain and immunohistochemistry for collagen type IV. [ABSTRACT FROM AUTHOR]

Personalized management of neuropathic pain is an unmet clinical need due to heterogeneity of the underlying aetiologies, incompletely understood pathophysiological mechanisms and limited efficacy of existing treatments. Recent studies on microRNA in pain preclinical models have begun to yield insights into pain-related mechanisms, identifying nociception-related species differences and pinpointing potential drug candidates. With the aim of bridging the translational gap towards the clinic, we generated a human pain-related integrative miRNA and mRNA molecular profile of the epidermis, the tissue hosting small nerve fibres, in a deeply phenotyped cohort of patients with sodium channel-related painful neuropathy not responding to currently available therapies. We identified four miRNAs strongly discriminating patients from healthy individuals, confirming their effect on differentially expressed gene targets driving peripheral sensory transduction, transmission, modulation and post-transcriptional modifications, with strong effects on gene targets including NEDD4. We identified a complex epidermal miRNA–mRNA network based on tissue-specific experimental data suggesting a cross-talk between epidermal cells and axons in neuropathy pain. Using immunofluorescence assay and confocal microscopy, we observed that Nav1.7 signal intensity in keratinocytes strongly inversely correlated with NEDD4 expression that was downregulated by miR-30 family, suggesting post-transcriptional fine tuning of pain-related protein expression. Our targeted molecular profiling advances the understanding of specific neuropathic pain fine signatures and may accelerate process towards personalized medicine in patients with neuropathic pain. [ABSTRACT FROM AUTHOR]

Cystoliths are phytoliths of silica and calcium carbonate and are produced in a few groups of dicotyledonous angiosperms. Anatomical and, more recently, phytolith studies have recorded them in different families. In the present review, we analyse and integrate both types of research to compile information about their formation and composition, their distribution in vascular plants, their relation with anatomy and systematics and their potential roles in plant tissues. We also include analyses of specimens belonging to families having poorly-known cystolith information. According to our review, cystoliths can be considered to be Si-Ca phytoliths. They are well described in eight families, and in 14 other families the information is inconclusive. The production of cystoliths is limited to dicotyledons, but there is no clear phylogenetic relation between the families that produce them. Cystolith accumulation is predominantly in the epidermis of leaves and/or in parenchymatic rays of woods. Diverse roles related to photosynthesis enhancement and as Ca reservoirs have been assigned to cystoliths. Knowledge of cystolith production among vascular plants is relevant for anatomical, systematic and ecological research, and also for biogeochemical studies due to their importance as a source of Ca and Si. [ABSTRACT FROM AUTHOR]

Dermatofibrosarcoma protuberans (DFSP) is a rare, slow-growing malignancy that often presents with an ambiguous clinical presentation due to its nonspecific findings. We present the case of a 41-year-old male who presented with a slow-growing mass on his abdomen that became protuberant and firm, prompting his desire to pursue excision. Upon return of histologic examination, the specimen was noted to be DFSP. DFSP is a rare cutaneous neoplasm that originates from the dermis and invades the underlying tissue creating a classic protuberant appearance. In some cases, chemotherapy and radiation may be indicated based on margins and locations. The sarcoma is notoriously complicated with early recurrence, making the disease process difficult to control. Surgeons should be familiar with this malignancy due to the indication of additional nonsurgical treatments and the necessity for long-term follow-up for surveillance of recurrence. [ABSTRACT FROM AUTHOR]

Background Hidradenitis suppurativa (HS) is a debilitating inflammatory skin disease characterized by painful nodules, drainage and scarring in skin folds. Injectable adalimumab is the only drug approved by the US Food and Drug Administration for the treatment of HS. Although systemic Janus kinase (JAK) inhibitors show promise, serious side-effects have been reported. There are no highly effective topical treatments for HS; furthermore, the contribution of epidermal keratinocytes to the intense inflammation has largely been unexplored. Objectives We investigated the role of keratinocytes and epidermal immune cells in HS inflammation at all Hurley stages of disease severity. We aimed to determine whether ruxolitinib can mitigate inflammation from keratinocytes and to develop a better understanding of how topical therapeutics might benefit patients with HS. Methods We used skin samples from 87 patients with HS (Hurley stages I–III) and 39 healthy controls to compare keratinocyte- and immune cell-driven epidermal inflammation, in addition to the response of lesional HS keratinocytes to treatment with interferon (IFN)-γ and ruxolitinib. We used haematoxylin and eosin staining, immunohistochemistry, immunoblotting and quantitative reverse-transcription polymerase chain reaction assessments in whole skin, isolated epidermis, and cultured keratinocytes from healthy controls and both nonlesional and lesional HS skin to identify and define epidermal and keratinocyte-mediated inflammation in HS and how this may be targeted by therapeutics. Results HS lesional keratinocytes autonomously secreted high levels of chemokines, such as CCL2, CCL3 and CXCL3, which recruited neutrophils, CD8 T cells, and natural killer cells to the epidermis. Keratinocytes were the dominant source of tumour necrosis factor-α and interleukin (IL)-6 in HS lesions with little to no contribution from underlying dermal immune cells. In the presence of IFN-γ, which is dependent on immune cell infiltrate in vivo , keratinocytes expressed increased levels of additional cytokines including IL-1β, IL-12, IL-23 and IL-36γ. The JAK inhibitor ruxolitinib mitigated the expression of inflammatory cytokines and chemokines in HS lesional keratinocytes, thus providing a rationale for future study as a topical treatment for HS. Conclusions This study demonstrates that keratinocytes actively recruit immune cells to HS epidermis and interactions between these cells drive a broad inflammatory profile in HS epidermis. Targeting epidermal inflammation in HS with novel topical formulations may be highly efficacious with reduced systemic side-effects. [ABSTRACT FROM AUTHOR]

Plants develop in the absence of cell migration. As such, cell division and differentiation need to be coordinated for functional tissue formation. Cellular valves on the plant epidermis, stomata, are generated through a stereotypical sequence of cell division and differentiation events. In Arabidopsis , three master regulatory transcription factors, SPEECHLESS (SPCH), MUTE and FAMA, sequentially drive initiation, proliferation and differentiation of stomata. Among them, MUTE switches the cell cycle mode from proliferative asymmetric division to terminal symmetric division and orchestrates the execution of the single symmetric division event. However, it remains unclear to what extent MUTE regulates the expression of cell cycle genes through the symmetric division and whether MUTE accumulation itself is gated by the cell cycle. Here, we show that MUTE directly upregulates the expression of cell cycle components throughout the terminal cell cycle phases of a stomatal precursor, not only core cell cycle engines but also check-point regulators. Time-lapse live imaging using the multicolor Plant Cell Cycle Indicator revealed that MUTE accumulates up to the early G2 phase, whereas its successor and direct target, FAMA, accumulate at late G2 through terminal mitosis. In the absence of MUTE , meristemoids fail to differentiate and their G1 phase elongates as they reiterate asymmetric divisions. Together, our work provides the framework of cell cycle and master regulatory transcription factors to coordinate a single symmetric cell division and suggests a mechanism for the eventual cell cycle arrest of an uncommitted stem-cell-like precursor at the G1 phase. [ABSTRACT FROM AUTHOR]

Plants produce a large variety of lipophilic metabolites, many of which are secreted by cells and accumulated in apoplasts. These compounds often play a role to protect plants from environmental stresses. However, little is known about how these lipophilic compounds are secreted into apoplastic spaces. In this study, we used shikonin-producing cultured cells of Lithospermum erythrorhizon as an experimental model system to analyze the secretion of lipophilic metabolites, taking advantage of its high production rate and the clear inducibility in culture. Shikonin derivatives are lipophilic red naphthoquinone compounds that accumulate exclusively in apoplastic spaces of these cells and also in the root epidermis of intact plants. Microscopic analysis showed that shikonin is accumulated in the form of numerous particles on the cell wall. Lipidomic analysis showed that L. erythrorhizon cultured cells secrete an appreciable portion of triacylglycerol (24–38% of total triacylglycerol), composed predominantly of saturated fatty acids. Moreover, in vitro reconstitution assay showed that triacylglycerol encapsulates shikonin derivatives with phospholipids to form lipid droplet-like structures. These findings suggest a novel role for triacylglycerol as a matrix lipid, a molecular component involved in the secretion of specialized lipophilic metabolites. [ABSTRACT FROM AUTHOR]

Inonotus obliquus is a medicinal fungus with potential for use in various health applications. To better utilize this fungus, this study focused on epidermis and internal tissues of five sclerotia from different regions in Jilin, Inner Mongolia, and Heilongjiang, examining their polyphenols, polysaccharides, flavonoids, and total triterpenes contents. And evaluated the extracts from sclerotia for their total antioxidant capacity and scavenging ability of DPPH free radicals. The study also isolated the associated fungi from the epidermis and internal tissues of three sclerotia. Results revealed that the polyphenol content was higher in the epidermis than in internal tissue of every sclerotium. However, flavonoid and total triterpenoid content was lower in the epidermis of every sclerotium. The polysaccharide content was no significant in different parts of three sclerotia, but the epidermal polysaccharide content in two sclerotia was significantly higher than in internal tissues. The internal tissue extracts from tested sclerotia exhibited better scavenging ability of DPPH free radicals than those from the epidermis. There was no significant difference in total antioxidant capacity among different parts of three sclerotia, and the internal tissues' total antioxidant capacity in two sclerotia was higher than the epidermis. The number and species of associated fungi in the internal tissues were far less than that in the epidermis. The study suggests separating the epidermis and internal tissue for medicinal use. The research provides insights into the bioactive components and associated fungi of I. obliquus to inform its practical application in medicine. [ABSTRACT FROM AUTHOR]

In plants, plastids are thought to interconvert to various forms that are specialized for photosynthesis, starch and oil storage, and diverse pigment accumulation. Post-endosymbiotic evolution has led to adaptations and specializations within plastid populations that align organellar functions with different cellular properties in primary and secondary metabolism, plant growth, organ development, and environmental sensing. Here, we review the plastid biology literature in light of recent reports supporting a class of 'sensory plastids' that are specialized for stress sensing and signaling. Abundant literature indicates that epidermal and vascular parenchyma plastids display shared features of dynamic morphology, proteome composition, and plastid–nuclear interaction that facilitate environmental sensing and signaling. These findings have the potential to reshape our understanding of plastid functional diversification. [ABSTRACT FROM AUTHOR]

Objectives Evidence shows that dysfunctional SSc keratinocytes contribute to fibrosis by altering dermal homeostasis. Whether IL-25, an IL-17 family member regulating many epidermal functions, takes part in skin fibrosis is unknown. Here we address the role of IL-25 in skin fibrosis. Methods The expression of IL-25 was evaluated by immunofluorescence and in situ hybridization in 10 SSc and seven healthy donor (HD) skin biopsies. Epidermal equivalents (EE) reconstituted by primary HD keratinocytes were used as a model to study transcriptomic changes induced by IL-25 in the epidermis. RNA expression profile in EEs was characterized by RNAseq. The conditioned medium (CM) from primary SSc and HD keratinocytes primed with IL-25 was used to stimulate fibroblasts. IL-6, IL-8, MMP-1, type-I collagen (Col-I), and fibronectin production by fibroblasts was assessed by ELISA. Results SSc epidermis expressed lower levels of IL-25 compared with HDs. In EEs, IL-25 regulated several molecular pathways related to wound healing and extracellular matrix remodelling. Compared with control CM, the CM from IL-25-primed keratinocytes enhanced the fibroblast production of MMP-1, IL-6 and IL-8, but not of Col-I nor fibronectin. However, IL-25 significantly reduced the production of Col-I when applied directly to fibroblasts. The activation of keratinocytes by IL-25 was receptor-dependent and evident after a very short incubation time (10 min), largely mediated by IL-1, suggesting enhanced and specific release of preformed mediators. Conclusions These results show that IL-25 participates in skin homeostasis, and its decreased expression in SSc may contribute to skin fibrosis by favouring extracellular matrix deposition over degradation. [ABSTRACT FROM AUTHOR]

The Moso bamboo (Phyllostachys edulis) leaf copes well with cold winters in southeastern China. However, until now, there has been almost no research on its adaptation mechanisms to cold weather. Herein, we found that the Moso bamboo leaf has evolved several anatomical structures that may play a role in enhancing its cold tolerance. These structures include fewer fusiform cells, smaller bulliform cells, lower stomata density and many more trichomes, as well as lower relative water content than in the leaf of a cold-sensitive bamboo species, Bambusa ventricosa. Untargeted metabolomic analysis revealed that the winter leaf of Moso bamboo had 10- to 1000-fold higher stress-resistant metabolites such as glutathione, trehalose and ascorbic acid than the leaf of B. ventricosa on both warm and cold days. In contrast to the leaves that grew on a warm day, some metabolites such as glutathione and trehalose increased dramatically in the leaves of Moso bamboo that grew on a cold day. However, they unexpectedly decreased in the leaf of B. ventricosa growing at cold temperatures. Transcriptome analysis revealed a cold stress response network that includes trehalose, glutathione, flavonoid metabolism, DNA repair, reactive oxygen species degradation, stress-associated genes and abiotic stress-related plant hormones such as jasmonic acid, abscisic acid and ethylene. The potential mediator transcription factors, such as EREBP, HSF, MYB, NAC and WRYK, were also significantly upregulated in Moso bamboo leaves growing at cold temperatures. Interestingly, many newly identified genes were involved in the transcriptome of the winter leaf of the Moso bamboo. Most of these new genes have not even been annotated yet. The above results indicate that the Moso bamboo leaf has evolved special histological structures, metabolic pathways and a cold stress-tolerant transcriptome to adapt to the cold weather in its distribution areas. [ABSTRACT FROM AUTHOR]

Background Stomatal pores in many species are separated from the atmosphere by different anatomical obstacles produced by leaf epidermal cells, especially by sunken stomatal crypts, stomatal antechambers and/or hairs (trichomes). The evolutionary driving forces leading to sunken or 'hidden' stomata whose antechambers are filled with hairs or waxy plugs are not fully understood. The available hypothetical explanations are based mainly on mathematical modelling of water and CO2 diffusion through superficial vs. sunken stomata, and studies of comparative autecology. A better understanding of this phenomenon may result from examining the interactions between the leaf cuticle and stomata and from functional comparisons of sunken vs. superficially positioned stomata, especially when transpiration is low, for example at night or during severe drought. Scope I review recent ideas as to why stomata are hidden and test experimentally whether hidden stomata may behave differently from those not covered by epidermal structures and so are coupled more closely to the atmosphere. I also quantify the contribution of stomatal vs. cuticular transpiration at night using four species with sunken stomata and three species with superficial stomata. Conclusions Partitioning of leaf conductance in darkness (g tw) into stomatal and cuticular contributions revealed that stomatal conductance dominated g tw across all seven investigated species with antechambers with different degrees of prominence. Hidden stomata contributed, on average, less to g tw (approx. 70 %) than superficial stomata (approx. 80 %) and reduced their contribution dramatically with increasing g tw. In contrast, species with superficial stomata kept their proportion in g tw invariant across a broad range of g tw. Mechanisms behind the specific behaviour of hidden stomata and the multipurpose origin of sunken stomata are discussed. [ABSTRACT FROM AUTHOR]

How serine/threonine phosphatases are spatially and temporally tuned by regulatory subunits is a fundamental question in cell biology. Ankyrin repeat, SH3 domain, proline-rich-region-containing proteins are protein phosphatase 1 catalytic subunit binding partners associated with cardiocutaneous diseases. Ankyrin repeat, SH3 domain, proline-rich-region-containing proteins localize protein phosphatase 1 catalytic subunit to cell-cell junctions, but how ankyrin repeat, SH3 domain, proline-rich-region-containing proteins localize and whether they regulate protein phosphatase 1 catalytic subunit activity in vivo is unclear. Through a Caenorhabditis elegans genetic screen, we find that loss of the ankyrin repeat, SH3 domain, proline-rich-region-containing protein homolog, APE-1, suppresses a pathology called "jowls," providing us with an in vivo assay for APE-1 activity. Using immunoprecipitations and mass spectrometry, we find that APE-1 binds the protein phosphatase 1 catalytic subunit called GSP-2. Through structure-function analysis, we discover that APE-1's N-terminal half directs the APE-1-GSP-2 complex to intercellular junctions. Additionally, we isolated mutations in highly conserved residues of APE-1's ankyrin repeats that suppress jowls yet do not preclude GSP-2 binding, implying APE-1 does more than simply localize GSP-2. Indeed, in vivo reconstitution of APE-1 suggests the ankyrin repeats modulate phosphatase output, a function we find to be conserved among vertebrate homologs. [ABSTRACT FROM AUTHOR]

Skin hydration and the barrier properties of the stratum corneum have been reported to be influential factors in the potential for retention of solid and semi-solid substances on the skin surface. The measurement of these characteristics of the skin, however, remains relatively uncommon in exposure assessments performed by industrial or occupational hygienists, even when the focus of the assessment is exposure to the skin. This study provides measurements of skin hydration using multiple instruments and multiple relevant skin site locations for comparative analysis. Three different measurement metrics, trans-epidermal water loss (TEWL), hydration index (HI), and percent hydration, were measured for 25 healthy volunteers at two different body locations for comparison: the center of the volar forearm, as previously recommended for interindividual comparison of hydration and barrier property measurements, and also the palmar tip of the index finger. The purpose of the comparative measurements was to allow for comparison between other published baseline volar forearm measurements and the palmar skin, which has not often been quantitatively assessed and reported in the literature, but is a relevant skin surface for sampling of the hands. This comparison will allow for consideration of the potential influence of palmar wipe sampling protocols on TEWL or skin hydration, and for the evaluation of the influence of skin hydration and TEWL on measured dermal transfer values. Collectively, the skin hydration levels and barrier properties at these two different measurement locations were found to be statistically significantly different, and as a result it is suggested that they be measured and recorded separately. Both measurement types and locations are likely to be important for the purposes of establishing skin hydration and health. Volar forearm measurements can also be important for understanding the underlying condition and barrier function of the skin, and palmar index finger measurements are necessary to understand the influence of both TEWL and skin hydration on quantitative dermal loading and transfer of solids and semi-volatile materials. [ABSTRACT FROM AUTHOR]

We describe reconstruction of a sternal cleft in a neonate using acellular dermal matrix, full-thickness calvarial bone graft and myocutaneous pectoralis flaps. Sternal cleft is rare, representing <1% of chest wall deformities [1]. [ABSTRACT FROM AUTHOR]

γδ T cells expressing Vγ5Vδ1 TCR originally develop in the embryonic thymus and migrate to the epidermis, forming dendritic epidermal T cells (DETCs) throughout life. It is thought that a TCR signal is essential for their development; e.g. lack of TCR signal-transducer ZAP70 significantly decreases DETC numbers. On the other hand, lack of ZAP70 does not affect Vγ5Vδ1+ T cells in the embryonic thymus; thus, the involvement of TCR signaling remains elusive. Here, we used SKG mice with attenuated TCR signaling rather than gene-knockout mice. In SKG mice, Vγ5+ T cells showed a marked decrease [10% of wild-type (WT)] in adult epidermis; however, there was just a moderate decrease (50% of WT) in the embryonic thymus. In early postnatal epidermis in SKG mice, substantial numbers of Vγ5+ T cells were observed (50% of WT). Their activation markers including CD122, a component of the IL-15 receptor indispensable for DETC proliferation, were comparable to those of WT. However, the Vγ5+ T cells in SKG mice did not proliferate and form DETCs thereafter. Furthermore, in SKG/+ mice, the number of thymic Vγ5Vδ1+ T cells increased, compared to SKG mice; however, the number of DETCs remained significantly lower than in WT, similar to SKG mice. Our results suggest that signaling via Vγ5Vδ1 TCR is indispensable for DETC development, with distinct contributions to embryonic development and postnatal proliferation. [ABSTRACT FROM AUTHOR]

A novel in vitro 3D micronucleus assay was developed in China using the EpiSkin™ 3D human skin model. This EpiSkin™ Micronucleus Assay showed good predictivity and reproducibility during internal validation and is expected to contribute to in vitro genotoxicity testing as a follow-up for positive results from 2D micronucleus assay. Having developed the assay in one laboratory, further work focused on the transferability and inter-laboratory reproducibility in two additional Chinese authority laboratories (Guangdong Provincial Center for Disease Control and Prevention and Zhejiang Institute for Food and Drug Control). Formal training was provided for both laboratories, which resulted in good transferability based on the results of two positive compounds, such as mitomycin C and vinblastine. Independent experiments were then performed, and inter-laboratory reproducibility was checked using 2-acetylaminofluorene, 5-fluorouracil, 2,4-dichlorophenol, and d -limonene. The dose-responses of the positive control chemical, mitomycin C, were similar to those of the developing laboratory, and all test chemicals were correctly classified by all laboratories. Overall, there was a good transferability as well as intra- and inter-laboratory reproducibility of the EpiSkin™ Micronucleus Assay. This study further confirmed the assay's robustness and provided confidence to enter following validation stages for scientific acceptance. [ABSTRACT FROM AUTHOR]

During tissue closures, such as embryonic dorsal closure in Drosophila melanogaster, a proximate extra-embryonic layer, amnioserosa, generates forces that drive migration of the flanking lateral embryonic epidermis, thereby zip-shutting the embryo. Arguably, this paradigm of tissue closure is also recapitulated in mammalian wound healing wherein proximate fibroblasts transform into contractile myofibroblasts, develop cell junctions, and form a tissue layer de novo: contraction of the latter then aids in wound closure. Given this parallelism between disparate exemplars, we posit a general principle of tissue closure via proximate cell layer-generated forces. Here, we have tested this hypothesis in pupal thorax closure wherein 2 halves of the presumptive adult thorax of Drosophila, the contralateral heminotal epithelia, migrate over an underlying larval epidermal cell layer. We show that the proximate larval epidermal cell layer promotes thorax closure by its active contraction, orchestrated by its elaborate actomyosin network-driven epithelial cell dynamics, cell delamination, and death--the latter being prefigured by the activation of caspases. Larval epidermal cell dynamics generate contraction forces, which when relayed to the flanking heminota--via their mutual integrin-based adhesions--mediate thorax closure. Compromising any of these contraction forcegenerating mechanisms in the larval epidermal cell layer slows down heminotal migration, while loss of its relay to the flanking heminota abrogates the thorax closure altogether. Mathematical modeling further reconciles the biophysical underpinning of this emergent mechanism of thorax closure. Revealing mechanism of thorax closure apart, these findings show conservation of an essential principle of a proximate cell layer-driven tissue closure. [ABSTRACT FROM AUTHOR]

Six cycles of recurrent selection for early shoot vigour in wheat resulted in significant increases in leaf width and shoot biomass. Here, in replicated controlled-environment studies, the effect of early shoot vigour on root biomass, rhizosheath size, root hair length, and cell size in the roots and leaves was examined across different cycles of selection. Increased shoot vigour was associated with greater root biomass, larger rhizosheath size, and longer root hairs. Our findings demonstrate that rhizosheath size was a reliable surrogate for root hair length in this germplasm. Examination of the root epidermis revealed that the 'cell body' of the trichoblasts (hair-forming cells) and the atrichoblasts (non-hair-forming cells) decreased in size as shoot vigour increased. Therefore, in higher vigour germplasm, longer root hairs emerged from smaller trichoblasts so that total trichoblast volume (root hair plus cell body) was generally similar regardless of shoot vigour. Similarly, the sizes of the four main cell types on the leaf epidermis became progressively smaller as shoot vigour increased, which also increased stomatal density. The relationship between shoot vigour and root traits is considered, and the potential contribution of below-ground root traits to performance and competitiveness of high vigour germplasm is discussed. [ABSTRACT FROM AUTHOR]

The functional significance of osteoderms—ossified bony structures in the dermis—has been a topic of discussion for many years in biological sciences. Although a protective function has received significant attention in the past, evidence is accumulating that osteoderms might play an important role during physiological activities, specifically thermoregulation. Previous studies have shown that, in crocodilians, the temperature of the skin overlying the osteoderms differs from that of the non-ossified skin during basking. The direction of these differences, however, appears to vary among studies, warranting the re-evaluation of a potential thermoregulatory function. In this study, we explored the thermal benefits of osteoderm expression in dwarf caimans (Paleosuchus palpebrosus). We compared the difference in dorsal and lateral skin temperatures (ΔT) between individuals with fully developed osteoderms and those devoid of any osteoderms, under three different temperature gradients. Our results show that although significant differences in ΔT are present between individuals and between temperature gradients, they do not relate to the expression of osteoderms. The findings of the present study question the thermoregulatory role that osteoderms play in P. palpebrosus , and vertebrates in general, and we put forward a series of alternative (physiological) hypotheses explaining their enigmatic nature. [ABSTRACT FROM AUTHOR]

The spatiotemporal regulation of gene expression is essential to ensure robust phenotypic outcomes. Pigmentation patterns in Drosophila are determined by pigments biosynthesized in the developing epidermis and the cis-regulatory elements of the genes involved in this process are well-characterized. Here, we report that the known primary epidermal enhancer is dispensable for the transcriptional activation of ebony (involved in light-colored pigment synthesis) in the developing epidermis of Drosophila melanogaster. The evidence was obtained by introducing an approximately 1 kbp deletion at the primary epidermal enhancer by genome editing. The effect of the primary epidermal enhancer deletion on pigmentation and on the endogenous expression pattern of a mCherry-fused ebony allele was examined in the abdomen. The expression levels of the mCherry-fused ebony in the primary epidermal enhancer-deleted strains were slightly higher than that of the control strain, indicating that the sequences outside the primary epidermal enhancer have an ability to drive an expression of this gene in the epidermis. Interestingly, the primary epidermal enhancer deletion resulted in a derepression of this gene in the dorsal midline of the abdominal tergites, where dark pigmentation is present in the wild-type individuals. This indicated that the primary epidermal enhancer fragment contains a silencer. Furthermore, the endogenous expression pattern of ebony in the 2 additional strains with partially deleted primary epidermal enhancer revealed that the silencer resides within a 351-bp fragment in the 5' portion of the primary epidermal enhancer. These results demonstrated that deletion assays combined with reporter assays are highly effective in detecting the presence of positively and negatively regulating sequences within and outside the focal cis-regulatory elements. [ABSTRACT FROM AUTHOR]

Nelumbonaceae, along with Proteaceae and Platanaceae, comprise a sister clade to the family Sabiaceae in the order Proteales, although these families were previously not considered to be related. In this work, we investigated fruitlet development in Nelumbo with a special focus on the principal events of fruitlet ontogenesis and its pericarp histogenesis, aiming to determine whether fruit structure and histology can provide characters supporting current systematic positions and affinities of these families and reveal potential synapomorphies for the order. We demonstrated for the first time that each carpel comprises a biseriate outer and inner epidermis and thick mesophyll with numerous air canals, which differentiate after pollination into a pericarp with a biseriate palisade exocarp and undifferentiated endocarp. The mesocarp differentiated into a protective hard peripheral zone and a soft inner zone. We propose the following additional autapomorphies for Nelumbonaceae: (1) the development of a specific zone of palisade cells of the subdermal layer of the exocarp with U-shaped cell walls thickening to form a light line around the locule, and potentially preventing apoplastic water transport; (2) the presence of a soft inner parenchymatous zone of the pericarp comprising numerous air cavities, channels and layers of spongy parenchyma, which can function as a seed cushion; (3) simultaneous growth of pollinated and unpollinated fruiting carpels up until the middle developmental stages; and (4) intensive development of the embryo and the seed at the late developmental stage in both Nelumbo spp. which has not been reported in any other member of Proteales. The presence of numerous vascular bundles in the fruitlets of Nelumbonaceae, Platanaceae and some Proteaceae is a synapomorphy for these three families forming a well-supported clade in Proteales. [ABSTRACT FROM AUTHOR]

Introduction: Many patients have had penile enhancement surgery and the surgeon try to reduce postoperative complications including hemorrage, infection, wound dehiscence etc. we want to evaluate the benefits of closed wound drainage system with negative pressure in penile enhancement surgery. Objective: we want to evaluate the benefits of closed wound drainage system with negative pressure in penile enhancement surgery. Methods: We have experienced 500 penile enhancement surgery. We adopted a pre-pubic minimal incision and dissected penile shaft and pre-pubic space. Inserted graft materials were Allograft dermal grafts which were fixed at the Buck's fascia. And we dissected fundi-form ligaments and sutured transversely pre-pubic dead space with PDS 2.0. In group 1, silastic drain were inserted in 250cases in order to drain postoperative bleeding and prevent inflammation. In group 2, the remain 250 cases adopted closed wound drainage system with negative pressure. Results: In group 1, the wound infecton rate was 2.9% and no dermal graft infection was showed. In group 2, the wound infection rate was 0.6% and no dermal graft infection was appeared. Group 1 using closed wound drainage system with negative pressure is more effective than group 2 using silastic drain in order to reduce wound infection rate. Conclusions: In penile augmentation surgery using Allogenic dermis, Using closed wound drainage system with negative pressure is safer than using silastic drain as postoperative drainage system. Disclosure: No. [ABSTRACT FROM AUTHOR]

Introduction: Many patients have had penile enhancement surgery and the surgeon try to reduce postoperative complications including hemorrage, infection, wound dehiscence etc. we want to evaluate the benefits of closed wound drainage system with negative pressure in penile enhancement surgery. Objective: we want to evaluate the benefits of closed wound drainage system with negative pressure in penile enhancement surgery. Methods: We have experienced 500 penile enhancement surgery. We adopted a pre-pubic minimal incision and dissected penile shaft and pre-pubic space. Inserted graft materials were Allograft dermal grafts which were fixed at the Buck's fascia. And we dissected fundi-form ligaments and sutured transversely pre-pubic dead space with PDS 2.0. In group 1, silastic drain were inserted in 250cases in order to drain postoperative bleeding and prevent inflammation. In group 2, the remain 250 cases adopted closed wound drainage system with negative pressure. Results: In group 1, the wound infecton rate was 2.9% and no dermal graft infection was showed. In group 2, the wound infection rate was 0.6% and no dermal graft infection was appeared. Group 1 using closed wound drainage system with negative pressure is more effective than group 2 using silastic drain in order to reduce wound infection rate. Conclusions: In penile augmentation surgery using Allogenic dermis, Using closed wound drainage system with negative pressure is safer than using silastic drain as postoperative drainage system. Disclosure: No. [ABSTRACT FROM AUTHOR]

Actin and myosin mediate the epidermal cell contractions that elongate the Caenorhabditis elegans embryo from an ovoid to a tubularshaped worm. Contraction occurs mainly in the lateral epidermal cells, while the dorsoventral epidermis plays a more passive role. Two parallel pathways trigger actinomyosin contraction, one mediated by LET-502/Rho kinase and the other by PAK-1/p21 activated kinase. A number of genes mediating morphogenesis have been shown to be sufficient when expressed either laterally or dorsoventrally. Additional genes show either lateral or dorsoventral phenotypes. This led us to a model where contractile genes have discrete functions in one or the other cell type. We tested this by examining several genes for either lateral or dorsoventral sufficiency. LET-502 expression in the lateral cells was sufficient to drive elongation. MEL-11/Myosin phosphatase, which antagonizes contraction, and PAK-1 were expected to function dorsoventrally, but we could not detect tissue-specific sufficiency. Double mutants of lethal alleles predicted to decrease lateral contraction with those thought to increase dorsoventral force were previously shown to be viable. We hypothesized that these mutant combinations shifted the contractile force from the lateral to the dorsoventral cells and so the embryos would elongate with less lateral cell contraction. This was tested by examining 10 single and double mutant strains. In most cases, elongation proceeded without a noticeable alteration in lateral contraction. We suggest that many embryonic elongation genes likely act in both lateral and dorsoventral cells, even though they may have their primary focus in one or the other cell type. [ABSTRACT FROM AUTHOR]

Although skin health is of critical importance for all horse owners, understanding of cutaneous pH and trans-epidermal water loss (TEWL) and the normal ranges of these variables is lacking. Cutaneous pH and TEWL measures provide insight into the barrier function of the epidermis and have the potential to determine the resident dermal microbiota. However, these measures have been recorded to fluctuate due to a variety of factors such as environment and anatomical locations in other species. Accordingly, the objectives of this study were to identify the impacts of anatomical location, weather, and time of day on cutaneous pH and TEWL in equines. This study utilized nine (n = 9) stock type mares, group-housed in a pasture setting at Southern Illinois University Equine Center. Researchers measured cutaneous pH and TEWL three times (6:00 AM, 12:00 PM, 6:00 PM) daily across five anatomical locations (nose, whither, heart-girth, mid-back, and base of tail) for five consecutive days. All statistical analysis was conducted using SAS On Demand for Academics (P < 0.05). Analysis of changes in variables associated with time, anatomical location, and day were conducted utilizing a PROC GLM three-way repeated measures ANOVA utilizing a Greenhouse-Geiser correction. Cutaneous pH results displayed significant main effects of day (P = 0.0052) and time (P = 0.0073) as well as a significant interaction of day and location (P = 0.0004). Mean cutaneous pH fluctuated daily, however, certain anatomical locations fluctuated more than others each day. Additionally, pH was highest in the morning (mean of 7.28) and lowest in the evening (mean 7.011). However, the mean overall pH for the study is 7.14 which is congruent with other work. TEWL measurements had significant main effects of day (P < 0.0001), time (P < 0.0001), and location (P = 0.0231), as well as a significant interaction of day, time, and location (P < 0.0001). TEWL measurements fluctuated with day, likely a result of weather changes. Mean TEWL measurements were less in the morning (mean 24.68) and greatest in the afternoons (mean 38.52). Overall mean TEWL measurement was 30.25. The results of this work indicate fluctuations in dermal barrier variables are associated with day, anatomical location, and time of day. These findings may have implications for applications of dermal treatments for horses as well as catalog the natural fluctuations which may affect future research. [ABSTRACT FROM AUTHOR]

Umbilical lumps are a common presentation that can represent a diagnostic challenge as the differentials are broad. Epidermal inclusion cysts occur when epidermal cells are implanted in the dermis following trauma, or surgery. Although epidermal inclusion cysts are common, they are rarely cause of umbilical mass, with less than 10 cases described in the literature. Very few cases have been reported following abdominal surgery and none following laparoscopy. These lesions can occur with or without pain, mass, redness or spontaneous discharge and symptoms can persist for years. This paper reports a case of an umbilical epidermal inclusion cyst in a 52-year-old female presenting with a 6-week history of a painful, red umbilical lump on a background of two previous diagnostic laparoscopies. This was successfully treated with complete excision of the lesion. [ABSTRACT FROM AUTHOR]

Actinic keratoses (AKs) represent the precursor skin lesions in the pathogenesis of up to 87% of cutaneous squamous cell carcinomas (cSCCs). However, current treatment of AK lesions, at best, lead to only a 25% reduction in cSCC and relies on therapies that target abnormal keratinocytes using topical chemotherapy, immune stimulants or surgical resection. We have previously shown that 44% of AK tissue sample histologies contain koilocytes, wherein genotyping universally identified human papillomavirus 8 (HPV8). To determine the role of HPV8 in the pathogenesis of AKs, we used the K14–HPV8 complete early region (HPV8tg) to generate triple cross-lineage tracing transgenic mice: HPV8:K5-CreERT2:R26R-LoxP-flanked-Brainbow2.1 (Confetti reporter); HPV8:Lrig1-CreERT2:R26R-LoxP-flanked-Brainbow2.1; and HPV8:K15-PGR:R26R-LoxP-flanked-Brainbow2.1. Upon Cre activation, progeny clones exhibit one of four fluorescent colours. Compared to wild-type mice, all HPV8tg mice exhibited an expansion of keratinocytes in the hair follicle infundibulum (77.09 mm3 and 253.43 ± 54.15 mm3) and overlying epidermis. Clones from the Lrig1, but not K15, keratinocyte stem cell population were responsible for keratinocyte expansion of both the hair follicle infundibulum and overlying epidermis. Compared with wild-type mice, HPV8tg mice exhibited greater colony-forming efficiency (1.75 ± 0.69% vs. 6.27 ± 2.41%; n = 3), and, consistent with keratinocyte stem cell expansion, ΔNp63 expression was increased 4.14 ± 2.10-fold (P  < 0.05, n = 5). Flow-sorted epidermal clones from wild-type and HPV8tg mice were examined by RNA sequencing (n = 5). Warthin–Starry staining showed that the expanded population had no melanin 'cap' in our mouse models and human AK samples. In summary, expression of HPV8 early-region genes is associated with AK, wherein there is an expansion of the Lrig1, but not K15, keratinocyte stem cell population that results in epidermal thickening reminiscent of human AK pathology. These findings suggest that HPV8 results in translocation of hair follicle keratinocyte stem cells into the interfollicular epidermis without melanin production, making these cells susceptible to ultraviolet light transformation. [ABSTRACT FROM AUTHOR]

Staphylococcus cohnii is a potentially biotherapeutic skin commensal alleviating skin inflammation. Skin programming of inflammatory responses to Staphylococcus aureus is compartmentalized according to epidermal keratinocyte differentiation status. Https://doi.org/10.1093/bjd/ljac125 Specific skin-colonizing staphylococcal strains may confer protection against skin cancer,[1] have a therapeutic effect in the case of skin inflammation,[2] or promote the development or exacerbation of the chronic inflammatory skin disease atopic dermatitis (AD).[3],[4] Therefore, the interplay between staphylococci and the skin is of great interest. [Extracted from the article]

Heat stress in cattle has recently received growing attention because of anticipated increases in environmental temperature by global warming. Heat stress limits the production efficiency of cattle, and it is one of the principal causes of economic loss for beef cattle producers in these environments. Thermotolerance can be defined as the ability to maintain optimal growth, feed intake, and reproduction under the presence of heat stress, and it varies among individual animals and breeds. The objectives of the analysis were to investigate the amount of variation on epidermis thickness, test the effect of breed composition and age group on skin histology traits and to conduct a genome-wide association study on skin properties of beef cattle, focusing on the epidermis thickness. Skin biopsy samples were collected from 318 heifers from a UF multibreed population (animals ranging from 100% Brahman to 100% Angus), genotyped with the Bovine GGP F250K chip. Quality control was conducted with BLUPF90 software, including a call rate of 0.90 and a MAF < 0.01. BLUPF90 software was used to fit a single locus mixed model to test the effect of each marker. Breed group and age group were included as fixed effects. There is a significant effect in breed group ((P < 0.0001) and in age group (P < 0.0001). This study shows there is a large amount of variation in epidermis thickness across and within breed groups. Significant SNPs for the thickness of the epidermis were found in the HBEGF gene, which is a protein coding involved in several processes, including epidermal growth factor receptor signaling pathway and there is a variation across breed Skin histology traits are fundamental for the ability to lose heat more efficiently and allow the maintenance of normal body temperatures under extreme conditions. This study could contribute toward improving cattle's adaptation to thermal stress. [ABSTRACT FROM AUTHOR]