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Uplaonkar, Shilpa V., Mandakini Tengli, Syeda Farheen e Pratima S. "Histopathological Study of Tumours of Epidermis and Epidermal Appendages". Indian Journal of Pathology: Research and Practice 6, n.º 2 (Part-2) (2017): 460–66. http://dx.doi.org/10.21088/ijprp.2278.148x.62(pt-ii)17.22.
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Bogdanova, I. O., e L. A. Kartseva. "Leaf epidermal structure of extant gnetales (Gnetum L.) and the Middle Jurassic bennettitales (Nilssoniopteris Nathorst and Ptilophyllum Morris)". Palaeobotany 12 (2021): 56–87. http://dx.doi.org/10.31111/palaeobotany/2021.12.56.
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The leaf epidermis of four species of Gnetum L. and four species of the Jurassic Bennettitales (Nilssoniopteris Nathorst and Ptilophyllum Morris) were studied. In addition to the description of qualitative characters, the analysis of various quantitative characters was carried out using statistical methods. Coefficients of variation for quantitative characters of the epidermal structure in Gnetum range from 6.4 to 24.0%, in Ptilophyllum from 15.7 to 63.5%, in Nilssoniopteris from 18.0 to 39.9%. The sinuosity of tangential cell walls of the epidermal cells in the upper and lower epidermis is the stable character in both groups of plants (Cv ≤ 18.0%). In Ptilophyllum and Gnetum, the length of stomata demonstrates a low level of common variability (Cv ≤ 16.8%). A significant range in the coefficients of variation in both Gnetum and the studied genera of Bennettitales is typical for the number of epidermal cells per 1 mm2 of the upper and lower epidermis (17.5% ≤ Cv ≤ 31.9%), the area of the epidermal cells of the upper and lower epidermis (21.2% ≤ Cv ≤ 63.5%), and the number of stomata per 1 mm2 of the epidermis (29.3% ≤ Cv ≤ 39.9%). The similarity in the correlation structure of epidermal characters is manifested in the correlation between sinuosity of tangential cell walls of epidermal cells, the number of stomata per 1 mm2 of the epidermis, and size of epidermal cells, as well as between the length of the stomata and the number of epidermal cells and also between the stomatal index and the number of cells in epidermis. In Gnetum, the ratio of the number of differentiated stomata correlates with the number of aborted stomata per 1 mm2 of epidermis. In N. angustifolia and P. caucasicum, the number of stomata correlates with the number of papillae per 1 mm2.
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DESAI, Rinku Jitendrakumar, Vinay Madhukar RAOLE e Arun Omprakash ARYA. "Comparative Foliar Epidermal Studies in Coix lacryma-jobi L. andCoix aquatica Roxb. (Poaceae)". Notulae Scientia Biologicae 1, n.º 1 (7 de dezembro de 2009): 37–40. http://dx.doi.org/10.15835/nsb113449.
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As micromorphological knowledge was not available for Coix aquatica Roxb., the foliar epidermal studies were carried out for Coix lacryma-jobi L. and Coix aquatica Roxb. with the aim of determining the patterns of variation in their epidermal characteristics and assessing their value in species identification. Comparative foliar analysis was carried out by using light microscopy, after following routine scraping method. The characters of diagnostic importance in the identification of C. aquatica are the sparsely distributed prickle hairs with long pointed apex in the abaxial epidermis and dumbbell shaped silica cells in both the epidermises. The diagnostic characters for C. lacryma-jobi are the cross shaped silica cells and dumbbell shaped on the abaxial and adaxial epidermis respectively. The observed differences in certain micromorphological characters helps in identification of presently studied two species of Coix.
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du Cros, D. L., K. Isaacs e G. P. Moore. "Distribution of acidic and basic fibroblast growth factors in ovine skin during follicle morphogenesis". Journal of Cell Science 105, n.º 3 (1 de julho de 1993): 667–74. http://dx.doi.org/10.1242/jcs.105.3.667.
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Acidic and basic fibroblast growth factors (aFGF and bFGF) have been localized by immunochemistry in ovine skin during wool follicle morphogenesis. At 40 days of gestation, prior to the appearance of follicle primordia, bFGF immunoreactivity was detected in the intermediate and periderm layers of the epidermis and at the dermal-epidermal junction. Antibodies to aFGF did not bind to skin at this age. During early follicle formation, at 76 days of gestation, both FGFs were found in the epidermis and associated with the follicle primordia. Antibodies to aFGF, in particular, bound to the basal cells of the epidermis and the follicle cell aggregations. With the development of epidermal plugs, bFGF was confined to the intermediate layers of the epidermis and the dermal-epidermal junction, whereas aFGF staining was associated with the cells of the epidermis and the plugs. At 90 days, when many different stages of follicle development were in evidence, immunoreactivity for both FGFs was associated with the cells of the elongating epidermal column, particularly those adjacent to the dermal-epidermal junction. During follicle maturation, bFGF was found in the suprabasal layer of the epidermis, in the outer root sheath of the follicle and in the basement membrane zone surrounding the bulb matrix. Conversely, strong staining for aFGF was observed in the epidermis and pilary canal contiguous with the epidermis, and in cells of the upper bulb matrix of the follicle in the region of the keratogenous zone. Western blotting of extracts of mature follicles that had been isolated from the skin showed the presence of a major aFGF immunoreactive band with an apparent molecular mass of 27 kDa.(ABSTRACT TRUNCATED AT 250 WORDS)
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Lewis, Natasha Steffi, Geetika Chouhan, Vivek Belapurkar, Prateek Arora, Satyanarayan, Sri Rama Koti Ainavarapu e Mahendra Sonawane. "A new tension induction paradigm unravels tissue response and the importance of E-cadherin in the developing epidermis". International Journal of Developmental Biology 64, n.º 4-5-6 (2020): 343–52. http://dx.doi.org/10.1387/ijdb.190219ms.
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The epidermis, being the outermost epithelial layer in metazoans, experiences multiple external and self-generated mechanical stimuli. The tissue-scale response to these mechanical stresses has been actively studied in the adult stratified epidermis. However, the response of the developing bi-layered epidermis to differential tension and its molecular regulation has remained poorly characterised. Here we report an oil injection based method, which in combination with atomic force microscopy (AFM), allows manipulation as well as estimation of tension in the developing epidermis. Our results show that the injection of mineral oil into the brain ventricle of developing zebrafish embryos stretches the overlying epidermis. The epidermal tension increases linearly with the injected volume of oil and the injection of 14-17 nL oil results in a two-fold increase in epidermal tension. This increase in epidermal tension is sufficient to elicit a physiological response characterised by temporal changes in the cell cross-sectional area and an increase in cell proliferation. Our data further indicate that the depletion of E-cadherin in the epidermis is detrimental for tissue integrity under increased mechanical stress. The application of this experimental paradigm in a genetically tractable organism such as zebrafish can be useful in uncovering mechanisms of tension sustenance in the developing epidermis.
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Ogawa, Youichi, Manao Kinoshita, Shinji Shimada e Tatsuyoshi Kawamura. "Zinc in Keratinocytes and Langerhans Cells: Relevance to the Epidermal Homeostasis". Journal of Immunology Research 2018 (9 de dezembro de 2018): 1–11. http://dx.doi.org/10.1155/2018/5404093.
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In the skin, the epidermis is continuously exposed to various kinds of external substances and stimuli. Therefore, epidermal barriers are crucial for providing protection, safeguarding health, and regulating water balance by maintaining skin homeostasis. Disruption of the epidermal barrier allows external substances and stimuli to invade or stimulate the epidermal cells, leading to the elicitation of skin inflammation. The major components of the epidermal barrier are the stratum corneum (SC) and tight junctions (TJs). The presence of zinc in the epidermis promotes epidermal homeostasis; hence, this study reviewed the role of zinc in the formation and function of the SC and TJs. Langerhans cells (LCs) are one of the antigen-presenting cells found in the epidermis. They form TJs with adjacent keratinocytes (KCs), capture external antigens, and induce antigen-specific immune reactions. Thus, the function of zinc in LCs was examined in this review. We also summarized the general knowledge of zinc and zinc transporters in the epidermis with updated findings.
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Matsui, Takeshi. "Epidermal Barrier Development via Corneoptosis: A Unique Form of Cell Death in Stratum Granulosum Cells". Journal of Developmental Biology 11, n.º 4 (30 de novembro de 2023): 43. http://dx.doi.org/10.3390/jdb11040043.
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Epidermal development is responsible for the formation of the outermost layer of the skin, the epidermis. The establishment of the epidermal barrier is a critical aspect of mammalian development. Proper formation of the epidermis, which is composed of stratified squamous epithelial cells, is essential for the survival of terrestrial vertebrates because it acts as a crucial protective barrier against external threats such as pathogens, toxins, and physical trauma. In mammals, epidermal development begins from the embryonic surface ectoderm, which gives rise to the basal layer of the epidermis. This layer undergoes a series of complex processes that lead to the formation of subsequent layers, including the stratum intermedium, stratum spinosum, stratum granulosum, and stratum corneum. The stratum corneum, which is the topmost layer of the epidermis, is formed by corneoptosis, a specialized form of cell death. This process involves the transformation of epidermal keratinocytes in the granular layer into flattened dead cells, which constitute the protective barrier. In this review, we focus on the intricate mechanisms that drive the development and establishment of the mammalian epidermis to gain insight into the complex processes that govern this vital biological system.
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Stoler, A., R. Kopan, M. Duvic e E. Fuchs. "Use of monospecific antisera and cRNA probes to localize the major changes in keratin expression during normal and abnormal epidermal differentiation." Journal of Cell Biology 107, n.º 2 (1 de agosto de 1988): 427–46. http://dx.doi.org/10.1083/jcb.107.2.427.
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We report here the isolation and characterization of three antisera, each of which is specific for a single keratin from one of the three different pairs (K1/K10, K14/K5, K16/K6) that are differentially expressed in normal human epidermis and in epidermal diseases of hyperproliferation. We have used these antisera in conjunction with monospecific cRNA probes for epidermal keratin mRNAs to investigate pathways of differentiation in human epidermis and epidermal diseases in vivo and in epidermal cells cultured from normal skin and from squamous cell carcinomas in vitro. Specifically, our results suggest that: (a) the basal-specific keratin mRNAs are down-regulated upon commitment to terminal differentiation, but their encoded proteins are stable, and can be detected throughout the spinous layers; (b) the hyperproliferation-associated keratin mRNAs are expressed at a low level throughout normal epidermis when their encoded proteins are not expressed, but are synthesized at high levels in the suprabasal layers of hyperproliferating epidermis, coincident with the induced expression of the hyperproliferation-associated keratins in these cells; and (c) concomitantly with the induction of the hyperproliferation-associated keratins in the suprabasal layers of the epidermis is the down-regulation of the expression of the terminal differentiation-specific keratins. These data have important implications for our understanding of normal epidermal differentiation and the deviations from this process in the course of epidermal diseases of hyperproliferation.
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Dubé, Martin, e Pierre Morisset. "L'emploi des caractères épidermiques dans l'étude taxonomique du Festuca rubra lato sensu (Poaceae)". Canadian Journal of Botany 74, n.º 3 (1 de março de 1996): 469–85. http://dx.doi.org/10.1139/b96-058.
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The leaf epidermis from a collection of 33 specimens encompassing most of the morphological variation of Festuca rubra in Eastern Canada and including two cytotypes (2n = 42 and 2n = 56) is described with 16 characters. The leaf epidermal composition differs markedly between culms and vegetative shoots. Many epidermal characters, particularly those from the vegetative shoots, are among the best ones for distinguishing between the two cytotypes. Parallel analyses using nine anatomical characters show the greater taxonomical potential of epidermis. Keywords: Festuca rubra, leaf, epidermis, anatomy, cytotypes.
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Sabandar, Agave, A. Hiariej e D. E. Sahertian. "Struktur Sel Epidermis Dan Stomata Aegiceras corniculatum D dan Rhizophora apiculata pada Muara Sungai Desa Poka dan Desa Leahari". Biosel: Biology Science and Education 10, n.º 1 (1 de junho de 2021): 81. http://dx.doi.org/10.33477/bs.v10i1.1896.
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Research has been carried out to determine the cell structure of the epidermis and stomata in some mangrove plants in the species Aegiceras corniculatum and Rhizophora apiculata. Descriptive method is used to describe the cell structure of the epidermis and stomata of Aegiceras corniculatum and Rhizophora apiculata and quantitative leaves to calculate the number of stomata, number of epidermis and stomata index based on nail polish on the cross section of epidermal cells on the lower underside of the leaf using a light microscope, while the incision longitudinal to determine leaf thickness between the upper epidermis and the lower epidermis. The results showed that the two mangrove species that grow in the mouth of the Poka and Leahari villages namely Aegiceras corniculatum and Rhizophora apiculata were found to have the same anatomical structure and leaf anatomical characteristics in terms of the shape of epidermal cells, rectangular, octagonal, elongated, and irregular. Aegiceras corniculatum and Rhizophora apiculata have anomositic stomata type because neighboring cells surround the stomata and have the same shape as epidermal cells. Mangrove species in the river estuary of Poka Village have higher number of stomata and smaller epidermal size and lower stomata index than mangrove species in Leahari Village due to the influence of the shade.
Keywords: Aegiceras corniculatum, Rhizophora apiculata, Epidermal cells,
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Walker, Dan B., e David K. Bruck. "Incompetence of stem epidermal cells to dedifferentiate and graft". Canadian Journal of Botany 63, n.º 12 (1 de dezembro de 1985): 2129–32. http://dx.doi.org/10.1139/b85-300.
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An intact mature epidermis precluded formation of approach grafts of stems of five angiospermous species. When the epidermis was excised, unsclerified cortical tissue exhibited tissue responses resulting in wound closure, including cell dedifferentiation and redifferentiation into callus tissue. Removal of the epidermis from both partners resulted in a graft union. Cortical callus tissue proliferated and coalesced to bind the partners. None of these responses associated with grafting or wound closure occurred in either epidermal or subepidermal tissue in intact partners. Whereas cortical cells adjacent to a cut region reacted in a similar way to those underlying the cut, neighboring epidermal cells were usually unaltered. This developmental quiescence of epidermal cells is a unique characteristic, useful in studies of epidermal differentiation and determination.
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Lobo, Ghislaine Maria, Thaysi Ventura de Souza, Caroline Heinig Voltolini, Ademir Reis e Marisa Santos. "Leaf Epidermis of the RheophyteDyckia brevifoliaBaker (Bromeliaceae)". Scientific World Journal 2013 (2013): 1–7. http://dx.doi.org/10.1155/2013/307593.
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Some species ofDyckiaSchult. f., includingDyckia brevifoliaBaker, are rheophytes that live in the fast-moving water currents of streams and rivers which are subject to frequent flooding, but also period of low water. This study aimed to analyze the leaf epidermis ofD. brevifoliain the context of epidermal adaptation to this aquatic plant’s rheophytic habitat. The epidermis is uniseriate, and the cuticle is thickened. The inner periclinal and anticlinal walls of the epidermal cells are thickened and lignified. Stomata are tetracytic, located in the depressions in relation to the surrounding epidermal cells, and covered by peltate trichomes. While the epidermal characteristics ofD. brevifoliaare similar to those of Bromeliaceae species, this species has made particular adaptations of leaf epidermis in response to its rheophytic environment.
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Cnops, G., X. Wang, P. Linstead, M. Van Montagu, M. Van Lijsebettens e L. Dolan. "Tornado1 and tornado2 are required for the specification of radial and circumferential pattern in the Arabidopsis root". Development 127, n.º 15 (1 de agosto de 2000): 3385–94. http://dx.doi.org/10.1242/dev.127.15.3385.
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The cell layers of the Arabidopsis primary root are arranged in a simple radial pattern. The outermost layer is the lateral root cap and lies outside the epidermis that surrounds the ground tissue. The files of epidermal and lateral root cap cells converge on a ring of initials (lateral root cap/epidermis initial) from which the epidermal and lateral root cap tissues of the seedling are derived, once root growth is initiated after germination. Each initial gives rise to a clone of epidermal cells and a clone of lateral root cap cells. These initial divisions in the epidermal/lateral root cap initial are defective in tornado1 (trn1) and trn2 plants indicating a requirement for TRN1 and TRN2 for initial cell function. Furthermore, lateral root cap cells develop in the epidermal position in trn1 and trn2 roots indicating that TRN1 and TRN2 are required for the maintenance of the radial pattern of cell specification in the root. The death of these ectopic lateral root cap cells in the elongation zone (where lateral root cap cells normally die) results in the development of gaps in the epidermis. These observations indicate that TRN1 and TRN2 are required to maintain the distinction between the lateral root cap and epidermis and suggest that lateral root cap fate is the default state. It also suggests that TRN1 and TRN2 repress lateral root cap fate in cells in the epidermal location. Furthermore, the position-dependent pattern of root hair and non-root hair cell differentiation in the epidermis is defective in trn1 and trn2 mutants. Together these results indicate that TRN1 and TRN2 are required for the maintenance of both the radial pattern of tissue differentiation in the root and for the subsequent circumferential pattern within the epidermis.
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Böckelmann, PK, BS Ochandio e IJ Bechara. "Histological study of the dynamics in epidermis regeneration of the carp tail fin (Cyprinus carpio, Linnaeus, 1758)". Brazilian Journal of Biology 70, n.º 1 (fevereiro de 2010): 217–23. http://dx.doi.org/10.1590/s1519-69842010000100030.
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Teleostean fins when partially amputated suffer a regenerative process called epimorphic regeneration, characterized by the following stages: healing, based on the formation of a multistratified epidermal layer, the formation of a mass of pluripotent cells known as blastema, the differentiation of these cells, the synthesis and disposition of the extracellular matrix, morphological growth and restoration. The epidermis has a fundamental role in the regenerative process of fish fins, as the healing time of this structure leads it to a faster regenerative process and it also works as a defense against the external environment. In this sense, due to the fast regeneration shown by the epidermis, the aim of this paper is to study the histology of the regenerative dynamics of the carp fin tail (Cyprinus carpio), under the light and transmission electron microscope. Epidermic regeneration begins right in the first hours after the fin amputation and it continues throughout the regenerative process. After 24 hours, an apical epidermal cap is established. Cytoplasmatic prolongations and intercellular junctions are observed and the cells of the basal layer of the epidermis change from the cubic form to the cylindrical, due to the development of the cytoplasmatic organelles responsible for the synthesis of the basal membrane, lost after amputation. These results show the importance of histological studies in regenerative processes. We believe that the association of molecular biology with histological studies can throw further light onto these regenerative dynamics.
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Chidgey, Martyn, Cord Brakebusch, Erika Gustafsson, Alan Cruchley, Chris Hail, Sarah Kirk, Anita Merritt et al. "Mice lacking desmocollin 1 show epidermal fragility accompanied by barrier defects and abnormal differentiation". Journal of Cell Biology 155, n.º 5 (19 de novembro de 2001): 821–32. http://dx.doi.org/10.1083/jcb.200105009.
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The desmosomal cadherin desmocollin (Dsc)1 is expressed in upper epidermis where strong adhesion is required. To investigate its role in vivo, we have genetically engineered mice with a targeted disruption in the Dsc1 gene. Soon after birth, null mice exhibit flaky skin and a striking punctate epidermal barrier defect. The epidermis is fragile, and acantholysis in the granular layer generates localized lesions, compromising skin barrier function. Neutrophils accumulate in the lesions and further degrade the tissue, causing sloughing (flaking) of lesional epidermis, but rapid wound healing prevents the formation of overt lesions. Null epidermis is hyperproliferative and overexpresses keratins 6 and 16, indicating abnormal differentiation. From 6 wk, null mice develop ulcerating lesions resembling chronic dermatitis. We speculate that ulceration occurs after acantholysis in the fragile epidermis because environmental insults are more stringent and wound healing is less rapid than in neonatal mice. This dermatitis is accompanied by localized hair loss associated with formation of utriculi and dermal cysts, denoting hair follicle degeneration. Possible resemblance of the lesions to human blistering diseases is discussed. These results show that Dsc1 is required for strong adhesion and barrier maintenance in epidermis and contributes to epidermal differentiation.
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Luedke, Kory P., Jiro Yoshino, Chang Yin, Nan Jiang, Jessica M. Huang, Kevin Huynh e Jay Z. Parrish. "Dendrite intercalation between epidermal cells tunes nociceptor sensitivity to mechanical stimuli in Drosophila larvae". PLOS Genetics 20, n.º 4 (25 de abril de 2024): e1011237. http://dx.doi.org/10.1371/journal.pgen.1011237.
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An animal’s skin provides a first point of contact with the sensory environment, including noxious cues that elicit protective behavioral responses. Nociceptive somatosensory neurons densely innervate and intimately interact with epidermal cells to receive these cues, however the mechanisms by which epidermal interactions shape processing of noxious inputs is still poorly understood. Here, we identify a role for dendrite intercalation between epidermal cells in tuning sensitivity of Drosophila larvae to noxious mechanical stimuli. In wild-type larvae, dendrites of nociceptive class IV da neurons intercalate between epidermal cells at apodemes, which function as body wall muscle attachment sites, but not at other sites in the epidermis. From a genetic screen we identified miR-14 as a regulator of dendrite positioning in the epidermis: miR-14 is expressed broadly in the epidermis but not in apodemes, and miR-14 inactivation leads to excessive apical dendrite intercalation between epidermal cells. We found that miR-14 regulates expression and distribution of the epidermal Innexins ogre and Inx2 and that these epidermal gap junction proteins restrict epidermal dendrite intercalation. Finally, we found that altering the extent of epidermal dendrite intercalation had corresponding effects on nociception: increasing epidermal intercalation sensitized larvae to noxious mechanical inputs and increased mechanically evoked calcium responses in nociceptive neurons, whereas reducing epidermal dendrite intercalation had the opposite effects. Altogether, these studies identify epidermal dendrite intercalation as a mechanism for mechanical coupling of nociceptive neurons to the epidermis, with nociceptive sensitivity tuned by the extent of intercalation.
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Bin, Bum-Ho, Jinhyuk Bhin, Mikiro Takaishi, Koh-ei Toyoshima, Saeko Kawamata, Kana Ito, Takafumi Hara et al. "Requirement of zinc transporter ZIP10 for epidermal development: Implication of the ZIP10–p63 axis in epithelial homeostasis". Proceedings of the National Academy of Sciences 114, n.º 46 (23 de outubro de 2017): 12243–48. http://dx.doi.org/10.1073/pnas.1710726114.
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Skin tissues, in particular the epidermis, are severely affected by zinc deficiency. However, the zinc-mediated mechanisms that maintain the cells that form the epidermis have not been established. Here, we report that the zinc transporter ZIP10 is highly expressed in the outer root sheath of hair follicles and plays critical roles in epidermal development. We found that ZIP10 marked epidermal progenitor cell subsets and that ablating Zip10 caused significant epidermal hypoplasia accompanied by down-regulation of the transactivation of p63, a master regulator of epidermal progenitor cell proliferation and differentiation. Both ZIP10 and p63 are significantly increased during epidermal development, in which ZIP10-mediated zinc influx promotes p63 transactivation. Collectively, these results indicate that ZIP10 plays important roles in epidermal development via, at least in part, the ZIP10–zinc–p63 signaling axis, thereby highlighting the physiological significance of zinc regulation in the maintenance of skin epidermis.
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Verna, J. M. "In vitro analysis of interactions between sensory neurons and skin: evidence for selective innervation of dermis and epidermis". Development 86, n.º 1 (1 de abril de 1985): 53–70. http://dx.doi.org/10.1242/dev.86.1.53.
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Axons from dorsal root ganglion cells cultured in a serum-free medium on poly-L-lysine or collagen substrates interact differently with dermis and epidermis. The orientation of neurite growth is not changed by encountering mesenchymal cells migrating from the outgrowth zone of a dermal explant, and neurites form close membrane associations with some dermal cells; in contrast, neurites strongly avoid epidermis and deviate around the edge of an epidermal explant. When cultures are grown on polylysine this avoidance behaviour occurs at a distance from the epidermis. It is suppressed in the presence of necrotic epidermal cells. We suggest that this avoidance is due to epidermal diffusible factor(s) which bind preferentially to polylysine. The possibility of an absence of specific recognition cues between neurites and epidermal cells is discussed.
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Wang, H. Q., e R. C. Smart. "Overexpression of protein kinase C-alpha in the epidermis of transgenic mice results in striking alterations in phorbol ester-induced inflammation and COX-2, MIP-2 and TNF-alpha expression but not tumor promotion". Journal of Cell Science 112, n.º 20 (15 de outubro de 1999): 3497–506. http://dx.doi.org/10.1242/jcs.112.20.3497.
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Protein kinase Calpha (PKCalpha) is one of six PKC isoforms expressed in keratinocytes of mouse epidermis. To gain an understanding of the role of epidermal PKCalpha, we have localized its expression to specific cells of normal mouse skin and examined the effect of keratin 5 (K5) promoter directed expression of PKCalpha in transgenic mice. In normal mouse skin, PKCalpha was extensively expressed in the outer root sheath (ORS) keratinocytes of the anagen hair follicle and weakly expressed in keratinocytes of interfollicular epidermis. K5-targeted expression of PKCalpha to epidermal basal keratinocytes and follicular ORS keratinocytes resulted in a tenfold increase in epidermal PKCalpha. K5-PKCalpha mice exhibited no abnormalities in keratinocyte growth and differentiation in the epidermis. However, a single topical treatment with the PKC activator, 12-O-tetradecanoylphorbol-13-acetate (TPA) resulted in a striking inflammatory response characterized by edema and extensive epidermal infiltration of neutrophils that formed intraepidermal microabscesses in the epidermis. Compared to TPA-treated wild-type mice, the epidermis of TPA-treated K5-PKCalpha mice displayed increased expression of cyclooxygenase-2 (COX-2), the neutrophil chemotactic factor macrophage inflammatory protein-2 (MIP-2) mRNA and the proinflammatory cytokine TNFalpha mRNA but not IL-6 or IL-1alpha mRNA. To determine if K5-PKCalpha mice display an altered response to TPA-promotion, 7, 12-dimethylbenz[a]anthracene-initiated K5-PKCalpha mice and wild-type mice were promoted with TPA. No differences in papilloma incidence or multiplicity were observed between K5-PKCalpha mice and wild-type littermates. These results demonstrate that the overexpression of PKCalpha in epidermis increases the expression of specific proinflammatory mediators and induces cutaneous inflammation but has little to no effect on epidermal differentiation, proliferation or TPA tumor promotion.
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Efremova, Nadia, Marie-Christine Perbal, Alexander Yephremov, Winfried A. Hofmann, Heinz Saedler e Zsuzsanna Schwarz-Sommer. "Epidermal control of floral organ identity by class B homeotic genes in Antirrhinum and Arabidopsis". Development 128, n.º 14 (15 de julho de 2001): 2661–71. http://dx.doi.org/10.1242/dev.128.14.2661.
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To assess the contribution of the epidermis to the control of petal and stamen organ identity, we have used transgenic Antirrhinum and Arabidopsis plants that expressed the Antirrhinum class B homeotic transcription factors DEFICIENS (DEF) and GLOBOSA (GLO) in the epidermis. Transgene expression was controlled by the ANTIRRHINUM FIDDLEHEAD (AFI) promoter, which directs gene expression to the L1 meristematic layer and, later, to the epidermis of differentiating organs. Transgenic epidermal DEF and GLO chimeras display similar phenotypes, suggesting similar epidermal contributions by the two class B genes in Antirrhinum. Epidermal B function autonomously controls the differentiation of Antirrhinum petal epidermal cell types, but cannot fully control the pattern of cell divisions and the specification of sub-epidermal petal cell-identity by epidermal signalling. This non-autonomous control is enhanced if the endogenous class B genes can be activated from the epidermis. The developmental influence of epidermal B function in Antirrhinum stamen development is very limited. In contrast, epidermal B function in Arabidopsis can control most if not all epidermal and sub-epidermal differentiation events in petals and stamens, without any contribution from the endogenous class B genes. Possible reasons for differences in the efficacy of B-function-mediated cell communication between the two species are discussed. Interestingly, our experiments uncovered partial incompatibility between class B functional homologues. Although the DEFICIENS/PISTILLATA heterodimer is functional in transgenic Arabidopsis plants, the APETALA3/GLOBOSA heterodimer is not.
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Sandstrom, D. J., e L. L. Restifo. "Epidermal tendon cells require Broad Complex function for correct attachment of the indirect flight muscles in Drosophila melanogaster". Journal of Cell Science 112, n.º 22 (15 de novembro de 1999): 4051–65. http://dx.doi.org/10.1242/jcs.112.22.4051.
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Drosophila Broad Complex, a primary response gene in the ecdysone cascade, encodes a family of zinc-finger transcription factors essential for metamorphosis. Broad Complex mutations of the rbp complementation group disrupt attachment of the dorsoventral indirect flight muscles during pupal development. We previously demonstrated that isoform BRC-Z1 mediates the muscle attachment function of rbp(+) and is expressed in both developing muscle fibers and their epidermal attachment sites. We now report two complementary studies to determine the cellular site and mode of action of rbp(+) during maturation of the myotendinous junctions of dorsoventral indirect flight muscles. First, genetic mosaics, produced using the paternal loss method, revealed that the muscle attachment phenotype is determined primarily by the genotype of the dorsal epidermis, with the muscle fiber and the ventral epidermis exerting little or no influence. When the dorsal epidermis was mutant, the vast majority of muscles detached or chose ectopic attachment sites, regardless of the muscle genotype. Conversely, wild-type dorsal epidermis could support attachment of mutant muscles. Second, ultrastructural analysis corroborated and extended these results, revealing defective and delayed differentiation of rbp mutant epidermal tendon cells in the dorsal attachment sites. Tendon cell processes, the stress-bearing links between the epidermis and muscle, were reduced in number and showed delayed appearance of microtubule bundles. In contrast, mutant muscle and ventral epidermis resembled the wild type. In conclusion, BRC-Z1 acts in the dorsal epidermis to ensure differentiation of the myotendinous junction. By analogy with the cell-cell interaction essential for embryonic muscle attachment, we propose that BRC-Z1 regulates one or more components of the epidermal response to a signal from the developing muscle.
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Bosher, Julia M., Bum-Soo Hahn, Renaud Legouis, Satis Sookhareea, Robby M. Weimer, Anne Gansmuller, Andrew D. Chisholm, Ann M. Rose, Jean-Louis Bessereau e Michel Labouesse. "The Caenorhabditis elegans vab-10 spectraplakin isoforms protect the epidermis against internal and external forces". Journal of Cell Biology 161, n.º 4 (19 de maio de 2003): 757–68. http://dx.doi.org/10.1083/jcb.200302151.
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Morphogenesis of the Caenorhabditis elegans embryo is driven by actin microfilaments in the epidermis and by sarcomeres in body wall muscles. Both tissues are mechanically coupled, most likely through specialized attachment structures called fibrous organelles (FOs) that connect muscles to the cuticle across the epidermis. Here, we report the identification of new mutations in a gene known as vab-10, which lead to severe morphogenesis defects, and show that vab-10 corresponds to the C. elegans spectraplakin locus. Our analysis of vab-10 reveals novel insights into the role of this plakin subfamily. vab-10 generates isoforms related either to plectin (termed VAB-10A) or to microtubule actin cross-linking factor plakins (termed VAB-10B). Using specific antibodies and mutations, we show that VAB-10A and VAB-10B have distinct distributions and functions in the epidermis. Loss of VAB-10A impairs the integrity of FOs, leading to epidermal detachment from the cuticle and muscles, hence demonstrating that FOs are functionally and molecularly related to hemidesmosomes. We suggest that this isoform protects against forces external to the epidermis. In contrast, lack of VAB-10B leads to increased epidermal thickness during embryonic morphogenesis when epidermal cells change shape. We suggest that this isoform protects cells against tension that builds up within the epidermis.
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Cai, Ti, Keigo Nishida, Toshio Hirano e Paul A. Khavari. "Gab1 and SHP-2 promote Ras/MAPK regulation of epidermal growth and differentiation". Journal of Cell Biology 159, n.º 1 (7 de outubro de 2002): 103–12. http://dx.doi.org/10.1083/jcb.200205017.
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În epidermis, Ras can influence proliferation and differentiation; however, regulators of epidermal Ras function are not fully characterized, and Ras effects on growth and differentiation are controversial. EGF induced Ras activation in epidermal cells along with phosphorylation of the multisubstrate docking protein Gab1 and its binding to SHP-2. Expression of mutant Gab1Y627F deficient in SHP-2 binding or dominant-negative SHP-2C459S reduced basal levels of active Ras and downstream MAPK proteins and initiated differentiation. Differentiation triggered by both Gab1Y627F and SHP-2C459S could be blocked by coexpression of active Ras, consistent with Gab1 and SHP-2 action upstream of Ras in this process. To study the role of Gab1 and SHP-2 in tissue, we generated human epidermis overexpressing active Gab1 and SHP-2. Both proteins stimulated proliferation. In contrast, Gab1Y627F and SHP-2C459S inhibited epidermal proliferation and enhanced differentiation. Consistent with a role for Gab1 and SHP-2 in sustaining epidermal Ras/MAPK activity, Gab1−/− murine epidermis displayed lower levels of active Ras and MAPK with postnatal Gab1−/− epidermis, demonstrating the hypoplasia and enhanced differentiation seen previously with transgenic epidermal Ras blockade. These data provide support for a Ras role in promoting epidermal proliferation and opposing differentiation and indicate that Gab1 and SHP-2 promote the undifferentiated epidermal cell state by facilitating Ras/MAPK signaling.
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Nishida, H. "Localization of egg cytoplasm that promotes differentiation to epidermis in embryos of the ascidian Halocynthia roretzi". Development 120, n.º 2 (1 de fevereiro de 1994): 235–43. http://dx.doi.org/10.1242/dev.120.2.235.
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Embryogenesis in ascidians is of the mosaic type. This property suggests the presence of cytoplasmic factors in the egg that are responsible for specification of the developmental fates of early blastomeres. The epidermal cells that surround the entire tadpole larva originate exclusively from blastomeres of the animal hemisphere of early embryos. To obtain direct evidence for cytoplasmic determinants of epidermis fate, we carried out cytoplasmic transfer experiments by fusing blastomeres and anucleate cell fragments from various regions of eggs and embryos. Initially, presumptive non-epidermis blastomeres (blastomeres from the vegetal hemisphere) were fused to cytoplasmic fragments from various regions of blastomeres of 8-cell embryos of Halocynthia roretzi, and development of epidermal cells was monitored by following the expression of an epidermis- specific antigen, as well as by observations of morphology and the secretion of larval tunic materials. Formation of epidermis was observed when vegetal blastomeres were fused with cytoplasmic fragments from the presumptive epidermis blastomeres. The results suggested that cytoplasmic factors that promoted epidermis differentiation (epidermis determinants) were present in epidermis progenitors. Vegetal blastomeres only manifested this change in fate when fused with cytoplasmic fragments of roughly equal or larger size. Next, to examine the presence and localization of epidermis determinants in the uncleaved egg, cytoplasmic fragments from various regions of unfertilized and fertilized eggs were fused with the vegetal blastomeres. The results suggested that epidermis determinants were already present in unfertilized eggs and that they were segregated by movements of the ooplasm after fertilization. After the first phase of ooplasmic segregation, these determinants were widely distributed, with the highest activity being located in the equatorial region. There were no indications of regional differences in the activity within the equatorial region of eggs at this stage. After the second phase of ooplasmic segregation, prior to the first cleavage, the activity moved in the animal direction, namely, to the animal hemisphere, from which future epidermis-lineage blastomeres are normally formed.
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Nedukha, Olena, Olena Zolotareva e Maksym Netsvetov. "Phenotypic variability of epidermis structure and silicon inclusions in the leaves of Quercus robur in the Feofaniya Park". Plant Introduction 97-98 (30 de abril de 2023): 18–32. http://dx.doi.org/10.46341/pi2023001.
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The micromorphology of the leaf epidermis, localization, and silicon content in the epidermal cells of Quercus robur leaves growing in the shade and under direct sunlight in the Feofaniya Park (Kyiv, Ukraine) were studied using scanning electron microscopy and laser confocal microscopy. Silicon inclusions were found in the anticlinal and periclinal walls of adaxial epidermal cells, trichomes, guard cells of stomata, and walls of regular epidermal cells on the abaxial leaf surface, the amount of which varied according to the conditions of growth. Natural shading and the intensity of solar irradiation were found affecting the size of leaf blades, the ultrastructure of the leaf epidermis, and changes in the silicon content of oak leaves. Studies have shown that the anticlinal walls of the adaxial epidermis and the trichomes and stomata of the abaxial epidermis of leaves are the main silicon accumulators. The findings suggest that changes in leaf microstructure and silicon content contribute to maintaining optimal water balance in plants and can be regarded as signs of phenotypic plasticity in plants and an adaptive marker depending on the sunlight conditions of oak growth.
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Merritt, Anita J., Mohamed Y. Berika, Wenwu Zhai, Sarah E. Kirk, Baijing Ji, Matthew J. Hardman e David R. Garrod. "Suprabasal Desmoglein 3 Expression in the Epidermis of Transgenic Mice Results in Hyperproliferation and Abnormal Differentiation". Molecular and Cellular Biology 22, n.º 16 (15 de agosto de 2002): 5846–58. http://dx.doi.org/10.1128/mcb.22.16.5846-5858.2002.
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ABSTRACT The desmoglein 1 (Dsg1) and desmocollin 1 (Dsc1) isoforms of the desmosomal cadherins are expressed in the suprabasal layers of epidermis, whereas Dsg3 and Dsc3 are more strongly expressed basally. This differential expression may have a function in epidermal morphogenesis and/or may regulate the proliferation and differentiation of keratinocytes. To test this hypothesis, we changed the expression pattern by overexpressing human Dsg3 under the control of the keratin 1 (K1) promoter in the suprabasal epidermis of transgenic mice. From around 12 weeks of age, the mice exhibited flaking of the skin accompanied by epidermal pustules and thinning of the hair. Histological analysis of affected areas revealed acanthosis, hypergranulosis, hyperkeratosis, localized parakeratosis, and abnormal hair follicles. This phenotype has some features in common with human ichthyosiform diseases. Electron microscopy revealed a mild epidermal spongiosis. Suprabasally, desmosomes showed incorporation of the exogenous protein by immunogold labeling but were normal in structure. The epidermis was hyperproliferative, and differentiation was abnormal, demonstrated by expression of K14 in the suprabasal layer, restriction of K1, and strong induction of K6 and K16. The changes resembled those found in previous studies in which growth factors, cytokines, and integrins had been overexpressed in epidermis. Thus our data strongly support the view that Dsg3 contributes to the regulation of epidermal differentiation. Our results contrast markedly with those recently obtained by expressing Dsg3 in epidermis under the involucrin promoter. Possible reasons for this difference are considered in this paper.
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Eckert, Richard L., Gautam Adhikary, Christina A. Young, Ralph Jans, James F. Crish, Wen Xu e Ellen A. Rorke. "AP1 Transcription Factors in Epidermal Differentiation and Skin Cancer". Journal of Skin Cancer 2013 (2013): 1–9. http://dx.doi.org/10.1155/2013/537028.
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AP1 (jun/fos) transcription factors (c-jun, junB, junD, c-fos, FosB, Fra-1, and Fra-2) are key regulators of epidermal keratinocyte survival and differentiation and important drivers of cancer development. Understanding the role of these factors in epidermis is complicated by the fact that each protein is expressed, at different levels, in multiple cells layers in differentiating epidermis, and because AP1 transcription factors regulate competing processes (i.e., proliferation, apoptosis, and differentiation). Variousin vivogenetic approaches have been used to study these proteins including targeted and conditional knockdown, overexpression, and expression of dominant-negative inactivating AP1 transcription factors in epidermis. Taken together, these studies suggest that individual AP1 transcription factors have different functions in the epidermis and in cancer development and that altering AP1 transcription factor function in the basal versus suprabasal layers differentially influences the epidermal differentiation response and disease and cancer development.
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DiPersio, C. M., R. van der Neut, E. Georges-Labouesse, J. A. Kreidberg, A. Sonnenberg e R. O. Hynes. "alpha3beta1 and alpha6beta4 integrin receptors for laminin-5 are not essential for epidermal morphogenesis and homeostasis during skin development". Journal of Cell Science 113, n.º 17 (1 de setembro de 2000): 3051–62. http://dx.doi.org/10.1242/jcs.113.17.3051.
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Continuous regeneration and homeostasis of the stratified epidermis requires coordinated regulation of cell proliferation, cell differentiation, and cell survival. Integrin-mediated cell adhesion to the extracellular matrix has important roles in regulating each of these processes. Integrins alpha3beta1 and alpha6beta4 are both receptors on epidermal keratinocytes for the basement membrane protein laminin-5, the major ligand for epidermal adhesion in mature skin. Ablation in mice of either alpha3beta1 or alpha6beta4, through null mutation of the gene encoding the alpha3, alpha6, or beta4 integrin subunit, results in epidermal blistering of varying severity. Our previous studies showed that, despite blistering, differentiation and stratification of the epidermis appeared essentially normal in mice that lacked either alpha3beta1 or alpha6beta4. However, these studies did not definitively address the specific developmental importance of each integrin, since they may have overlapping and/or compensatory functions. Given the individual importance of alpha3beta1 or alpha6beta4 in maintaining the dermo-epidermal junction in mature skin, we sought to determine the importance of these integrins for embryonic skin development and epidermal morphogenesis. In the current study, we analyzed skin development in mutant embryos that completely lack both integrins alpha3beta1 and alpha6beta4. Although alpha3beta1/alpha6beta4-deficient embryos displayed epidermal blistering by stage E15.5 of development, they also retained regions of extensive epidermal adhesion to the basement membrane through stage E16.5, indicating alternative adhesion mechanisms. Apoptosis was induced in detached epidermis of alpha3beta1/alpha6beta4-deficient embryos, exemplifying vividly the importance of epithelial attachment to the basement membrane for cell survival. However, apoptotic cells were completely absent from attached epidermis of alpha3beta1/alpha6beta4-deficient embryos, showing that epithelial adhesion that occurred independently of alpha3beta1 and alpha6beta4 also protected cells from apoptosis. Remarkably, in the absence of the known laminin-5 binding integrins (alpha3beta1, alpha6beta4, and alpha6beta1), keratinocytes retained the capacity to proliferate in the epidermis, and epidermal stratification and skin morphogenesis appeared normal prior to blister formation. These findings show that while alpha3beta1 and alpha6beta4 are both required for integrity of the dermo-epidermal junction, neither one is essential for epidermal morphogenesis during skin development.
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Mac Neil, S., W. F. G. Tucker, R. A. Dawson, S. S. Bleehen e S. Tomlinson. "The calmodulin content of the epidermis in psoriasis". Clinical Science 69, n.º 6 (1 de dezembro de 1985): 681–86. http://dx.doi.org/10.1042/cs0690681.
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1. The calmodulin content of epidermis was determined by assay of biologically active and radioimmunoassayable calmodulin in epidermal biopsy samples of 16 normal control subjects and 36 patients with psoriasis. 2. Calmodulin levels in the involved epidermis of patients with psoriasis were significantly greater than in epidermis of control subjects, with both methods of calmodulin measurement. Levels of calmodulin in the uninvolved epidermis were also elevated but to a lesser degree, achieving statistical significance only when measured by radioimmunoassay. However, the degree of correlation between the two measurements of calmodulin was poor for the patient samples, suggesting that each may measure a different form of calmodulin. 3. The specificity of the elevated calmodulin in psoriatic epidermis was investigated by measuring calmodulin in another unrelated tissue. Calmodulin activity in circulating peripheral blood lymphocytes of seven patients with psoriasis was similar to that found in the lymphocytes of ten normal volunteers. 4. The relationship between calmodulin and the hyperproliferative state of the psoriatic epidermis was investigated. No significant increase in calmodulin activity was found after mitogen stimulation of lymphocyte proliferation or after Sellotape-stripping of the epidermis by a protocol which has been shown to cause hyperproliferation of the epidermis. 5. Elevated calmodulin in psoriatic epidermis therefore appears to be a localized phenomenon of the disease and does not appear to be a consequence of the hyperproliferative state of the epidermis.
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Murty, Rohan, Abishek Sankaranarayanan, Isabella I. Bowland, Juan Mena-Lapaix e Mark R. Prausnitz. "Angled Insertion of Microneedles for Targeted Antigen Delivery to the Epidermis". Pharmaceutics 14, n.º 2 (1 de fevereiro de 2022): 347. http://dx.doi.org/10.3390/pharmaceutics14020347.
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Peanut and tree nut allergies account for most food-induced anaphylactic events. The standard allergy immunotherapy approach involves subcutaneous injection, which is challenging because severe adverse reactions can occur when antigens spread systemically. Allergen localization within the epidermis (i.e., the upper 20–100 µm of skin) should significantly reduce systemic uptake, because the epidermis is avascular. Microneedle (MN) patches provide a convenient method for drug delivery to the skin, but they generally target both epidermis and dermis, leading to systemic delivery. In this study, we adapted MN technology for epidermal localization by performing angled insertion of 250 µm–long MNs that limits MN insertion depth mostly to the epidermis. We designed a biplanar insertion device to aid the repeatability of angled insertions into porcine skin ex vivo at specified angles (90°, 45°, and 20°). When compared to 90° insertions, MN application at 20° decreased mean insertion depth from 265 ± 45 µm to 97 ± 15 µm. Image analysis of histological skin sections revealed that acute-angle insertion increased epidermal localization of delivery for antigen-coated MNs from 25% ± 13% to 70% ± 21%. We conclude that angled insertion of MNs can target antigen delivery to epidermis.
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Zhao, Qiuxia, Rekha Rangan, Shinuo Weng, Cem Özdemir e Elif Sarinay Cenik. "Inhibition of ribosome biogenesis in the epidermis is sufficient to trigger organism-wide growth quiescence independently of nutritional status in C. elegans". PLOS Biology 21, n.º 8 (31 de agosto de 2023): e3002276. http://dx.doi.org/10.1371/journal.pbio.3002276.
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Interorgan communication is crucial for multicellular organismal growth, development, and homeostasis. Cell nonautonomous inhibitory cues, which limit tissue-specific growth alterations, are not well characterized due to cell ablation approach limitations. In this study, we employed the auxin-inducible degradation system in C. elegans to temporally and spatially modulate ribosome biogenesis, through depletion of essential factors (RPOA-2, GRWD-1, or TSR-2). Our findings reveal that embryo-wide inhibition of ribosome biogenesis induces a reversible early larval growth quiescence, distinguished by a unique gene expression signature that is different from starvation or dauer stages. When ribosome biogenesis is inhibited in volumetrically similar tissues, including body wall muscle, epidermis, pharynx, intestine, or germ line, it results in proportionally stunted growth across the organism to different degrees. We show that specifically inhibiting ribosome biogenesis in the epidermis is sufficient to trigger an organism-wide growth quiescence. Epidermis-specific ribosome depletion led to larval growth quiescence at the L3 stage, reduced organism-wide protein synthesis, and induced cell nonautonomous gene expression alterations. Further molecular analysis reveals overexpression of secreted proteins, suggesting an organism-wide regulatory mechanism. We find that UNC-31, a dense-core vesicle (DCV) pathway component, plays a significant role in epidermal ribosome biogenesis-mediated growth quiescence. Our tissue-specific knockdown experiments reveal that the organism-wide growth quiescence induced by epidermal-specific ribosome biogenesis inhibition is suppressed by reducing unc-31 expression in the epidermis, but not in neurons or body wall muscles. Similarly, IDA-1, a membrane-associated protein of the DCV, is overexpressed, and its knockdown in epidermis suppresses the organism-wide growth quiescence in response to epidermal ribosome biogenesis inhibition. Finally, we observe an overall increase in DCV puncta labeled by IDA-1 when epidermal ribosome biogenesis is inhibited, and these puncta are present in or near epidermal cells. In conclusion, these findings suggest a novel mechanism of nutrition-independent multicellular growth coordination initiated from the epidermis tissue upon ribosome biogenesis inhibition.
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Sidiq, Yasir, Daisuke Tamaoki e Takumi Nishiuchi. "Proteomic Profiling of Plant and Pathogen Interaction on the Leaf Epidermis". International Journal of Molecular Sciences 23, n.º 20 (12 de outubro de 2022): 12171. http://dx.doi.org/10.3390/ijms232012171.
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The plant epidermis is the first line of plant defense against pathogen invasion, and likely contains important regulatory proteins related to the plant–pathogen interaction. This study aims to identify the candidates of these regulatory proteins expressed in the plant epidermis. We performed comparative proteomic studies to identify rapidly and locally expressed proteins in the leaf epidermis inoculated with fungal phytopathogen. The conidia solutions were dropped onto the Arabidopsis leaf surface, and then, we collected the epidermal tissues from inoculated and mock-treated leaves at 4 and 24 hpi. The label-free quantification methods showed that expressions of Arabidopsis proteins, which are related to defense signals, such as BAK1, MKK5, receptor-like protein kinases, transcription factors, and stomatal functions, were rapidly induced in the epidermal tissues of inoculated leaves. In contrast, most of them were not differentially regulated by fugal inoculation in the whole leaves. These findings clearly indicate that epidermal proteomics can monitor locally expressed proteins in inoculated areas of plant tissues. We also identified the 61 fungal proteins, including effector-like proteins specifically expressed on the Arabidopsis epidermis. Our new findings suggested that epidermal proteomics is useful for understanding the local expressions of plant and fungal proteins related to their interactions.
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Jouin, Claude. "The ultrastructure of a gutless annelid, Parenterodrilus gen. no v. taenioides (= Astomus taenioides) (Polychaeta, Protodrilidae)". Canadian Journal of Zoology 70, n.º 9 (1 de setembro de 1992): 1833–48. http://dx.doi.org/10.1139/z92-250.
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An ultrastructural investigation of the mouthless protodrilid Parenterodrilus taenioides shows that the residual gut, with its very narrow ciliated lumen, has lost any digestive function. Salivary glands are retained in some anterior segments and their canals converge in a ventral area of the prostomium and open at the epidermal surface. The epidermal ciliation is much more developed than in any other protodrilid species. In the middle and posterior body segments the enlarged epidermal surface area is covered by a cuticle bearing an array of epidermal microvilli which are probably the site of active transport of dissolved organic compounds. The presence of numerous subcuticular coated vesicles and lysyosomes in the support cells suggests that particulate material from the ambient milieu is taken up by endocytosis and finally digested in the epidermis. The origin and nature of the organic substances that constitute the food of P. taenioides are still unknown. There are no symbiotic bacteria in the cuticle, epidermis, or residual gut. Abundant intracellular crystals in the nonfunctional gut indicate that this residual organ plays a role in the bioaccumulation of environmental substances which enter the body through the epidermis. The epidermis is the only absorptive surface of this unique polychaete, which is devoid of both a functional gut and symbiotic bacteria.
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Yang, Hui, Zheng Wang, Zhong Zhang, Chao Shu, Jiaqi Zhu, Ying Li e Junxiang Zhang. "Diversity of ‘Cabernet Sauvignon’ Grape Epidermis and Environmental Bacteria in Wineries from Different Sub-Regions of the Eastern Foothills of Helan Mountain, Ningxia". Foods 13, n.º 2 (12 de janeiro de 2024): 252. http://dx.doi.org/10.3390/foods13020252.
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Understanding the composition of the bacterial community on the epidermis of wine grapes and in winery environments, as well as the response of grape epidermal bacteria to climatic factors, plays a significant role in ensuring grape health and promoting grape conversion into wine. This study utilized high-throughput sequencing to explore the composition of the bacterial community on the wine grape epidermis and representative wineries of three sub-regions of the Eastern Foothills of Helan Mountain, Ningxia. The results showed that the bacterial diversity and richness in the Yongning (YN) sub-region were the highest, with Qingtongxia (QTX) having the lowest levels of grape epidermal bacteria. The bacterial diversity and richness were the highest in Yinchuan (YC) and the lowest in YN in the winery environment (p < 0.05). The composition of dominant bacteria on the grape epidermis and in winery environments of the three sub-regions was not different at the phylum and genus level, but the levels of these dominant bacteria were different among the sub-regions. There was a correlation between grape epidermal bacteria and climatic factors. Approximately 93% of the bacterial genera on the grape epidermal genera in the three sub-regions are present in the winery environment and contain all the dominant bacterial genera on the epidermis.
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Maksymowych, Roman, Norman Dollahon, Louise P. Di Cola e Joseph A. J. Orkwiszewski. "Chloroplasts in tissues of some herbaceous stems". Acta Societatis Botanicorum Poloniae 62, n.º 3-4 (2014): 123–26. http://dx.doi.org/10.5586/asbp.1993.017.
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Serial sections of mature stems of ten species of herbaceous dicotyledonous plants were examined by light microscopy and the number of chloroplasts per cell was estimated in epidermis, collenchyma and cortex. Chloroplast identification was made by both light and transmission electron microscopy. Chloroplasts were present in epidermis, collenchyma and cortex tissues of all stems examined. The smallest number of chloroplasts was observed in the epidermis. Collenchyma cells had the largest number of plastids in four of the genera and cortex cells had the largest number in the remaining six genera. The stem epidermis of all genera contained stomates as demonstrated by scanning electron microscopy and aceto-orcein stained epidermal peels.
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Soffer, Arad, Adnan Mahly, Krishnanand Padmanabhan, Jonathan Cohen, Orit Adir, Eidan Loushi, Yaron Fuchs, Scott E. Williams e Chen Luxenburg. "Apoptosis and tissue thinning contribute to symmetric cell division in the developing mouse epidermis in a nonautonomous way". PLOS Biology 20, n.º 8 (15 de agosto de 2022): e3001756. http://dx.doi.org/10.1371/journal.pbio.3001756.
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Mitotic spindle orientation (SO) is a conserved mechanism that governs cell fate and tissue morphogenesis. In the developing epidermis, a balance between self-renewing symmetric divisions and differentiative asymmetric divisions is necessary for normal development. While the cellular machinery that executes SO is well characterized, the extrinsic cues that guide it are poorly understood. Here, we identified the basal cell adhesion molecule (BCAM), a β1 integrin coreceptor, as a novel regulator of epidermal morphogenesis. In utero RNAi-mediated depletion of Bcam in the mouse embryo did not hinder β1 integrin distribution or cell adhesion and polarity. However, Bcam depletion promoted apoptosis, thinning of the epidermis, and symmetric cell division, and the defects were reversed by concomitant overexpression of the apoptosis inhibitor Xiap. Moreover, in mosaic epidermis, depletion of Bcam or Xiap induced symmetric divisions in neighboring wild-type cells. These results identify apoptosis and epidermal architecture as extrinsic cues that guide SO in the developing epidermis.
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Connor, M. J., e M. H. Smit. "Terminal-group oxidation of retinol by mouse epidermis. Inhibition in vitro and in vivo". Biochemical Journal 244, n.º 2 (1 de junho de 1987): 489–92. http://dx.doi.org/10.1042/bj2440489.
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Locally applied retinol is metabolized to retinoic acid in mouse epidermis in vivo. To characterize the oxidation system we investigated the ability of soluble extracts of hairless-mouse epidermis to convert retinol and retinal into retinoic acid. The extracts oxidized retinol to retinoic acid in two steps catalysed by two NAD+-dependent enzymes that were resolved on h.p.l.c. The first enzyme catalyses the reversible oxidation of retinol to retinal and is an alcohol dehydrogenase isoenzyme. The second enzyme oxidizes retinal to retinoic acid. Retinol oxidation by epidermal extracts was inhibited by the alcohol dehydrogenase inhibitor 4-methylpyrazole and by the polyene citral. The toxicity and relatively low potency at inhibiting the epidermal alcohol dehydrogenase isoenzyme curtailed the use of 4-methylpyrazole in vivo. However, citral significantly inhibited retinoic acid formation from retinol in the epidermis in vivo. The ability to inhibit the oxidation of retinol to retinoic acid in mouse epidermis provides a potential method to resolve the roles of retinol and retinoic acid in epithelial function.
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Steele, K. E., K. Stabler e L. VanderZanden. "Cutaneous DNA Vaccination Against Ebola Virus by Particle Bombardment: Histopathology and Alteration of CD3-positive Dendritic Epidermal Cells". Veterinary Pathology 38, n.º 2 (março de 2001): 203–15. http://dx.doi.org/10.1354/vp.38-2-203.
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We analyzed the localization of gold particles, expression of immunogenic protein, and histopathologic changes after vaccinating guinea pigs and mice with a DNA vaccine to the Ebola virus glycoprotein administered by cutaneous particle bombardment. Gold particles were deposited in all layers of the epidermis and in the dermis. Those in the epidermis were lost as the damaged layers sloughed, while those in the dermis were phagocytized by macrophages. Glycoprotein was demonstrated by immunohistochemistry primarily in keratinocytes in the epidermis and hair follicle epithelium and less frequently in dermal macrophages, fibroblasts, sebocytes, and cells that appeared to be Langerhans cells. The number of cells that expressed glycoprotein increased between 4 and 8 hours postvaccination, then decreased to near zero by 48 hours. The vaccine sites were histologically divisible into three zones. The central portion, zone 1, contained the most gold particles in the dermis and epidermis and had extensive tissue damage, including full-thickness epidermal necrosis. Zone 2 contained fewer gold particles in the epidermis and dermis and had less extensive necrosis. The majority of cells in which glycoprotein was expressed were in zone 2. Zone 3 contained gold particles only in the epidermis and had necrosis of only a few scattered cells. Regeneration of the epidermis in damaged areas was evident at 24 hours postvaccination and was essentially complete by day 5 in the mice and day 10 in the guinea pigs. Inflammatory changes were characterized by hemorrhage, edema, and infiltrates of neutrophils initially and by infiltrates of lymphocytes and macrophages at later times. In zone 1, inflammation affected both the epidermis and dermis. Peripherally, inflammation was relatively limited to the epidermis. CD3-positive dendritic epidermal cells were demonstrated in the epidermis and superficial hair follicles of unvaccinated immunocompetent mice and beige mice but not of SCID mice. These cells disappeared from all but the most peripheral portions of the vaccine sites of vaccinated mice within 24 hours. They reappeared slowly, failing to reach numbers comparable with unvaccinated mice by 35 days postvaccination. The epidermis of control guinea pigs also had CD3-positive cells, but they did not have dendrites. These findings should contribute to a better understanding of the mechanisms operating in response to DNA vaccination by particle bombardment.
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Bodó, Enikő, Benedikt Kany, Erzsébet Gáspár, Jana Knüver, Arno Kromminga, Yuval Ramot, Tamás Bíró et al. "Thyroid-Stimulating Hormone, a Novel, Locally Produced Modulator of Human Epidermal Functions, Is Regulated by Thyrotropin-Releasing Hormone and Thyroid Hormones". Endocrinology 151, n.º 4 (22 de fevereiro de 2010): 1633–42. http://dx.doi.org/10.1210/en.2009-0306.
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Several elements of the hypothalamic-pituitary-thyroid axis (HPT) reportedly are transcribed by human skin cell populations, and human hair follicles express functional receptors for TSH. Therefore, we asked whether the epidermis of normal human skin is yet another extrathyroidal target of TSH and whether epidermis even produces TSH. If so, we wanted to clarify whether intraepidermal TSH expression is regulated by TRH and/or thyroid hormones and whether TSH alters selected functions of normal human epidermis in situ. TSH and TSH receptor (TSH-R) expression were analyzed in the epidermis of normal human scalp skin by immunohistochemistry and PCR. In addition, full-thickness scalp skin was organ cultured and treated with TSH, TRH, or thyroid hormones, and the effect of TSH treatment on the expression of selected genes was measured by quantitative PCR and/or quantitative immunohistochemistry. Here we show that normal human epidermis expresses TSH at the mRNA and protein levels in situ and transcribes TSH-R. It also contains thyrostimulin transcripts. Intraepidermal TSH immunoreactivity is up-regulated by TRH and down-regulated by thyroid hormones. Although TSH-R immunoreactivity in situ could not be documented within the epidermis, but in the immediately adjacent dermis, TSH treatment of organ-cultured human skin strongly up-regulated epidermal expression of involucrin, loricrin, and keratins 5 and 14. Thus, normal human epidermis in situ is both an extrapituitary source and (possibly an indirect) target of TSH signaling, which regulates defined epidermal parameters. Intraepidermal TSH expression appears to be regulated by the classical endocrine controls that determine the systemic HPT axis.
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Fisher, Chris, e Edward J. Kollar. "Abnormal skin development in pupoid foetus (pf/pf) mutant mice". Development 87, n.º 1 (1 de junho de 1985): 47–64. http://dx.doi.org/10.1242/dev.87.1.47.
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At 13 days of development the epidermis of mice homozygous for the pupoid foetus (pf/pf) mutation varies in thickness between one and ten cell layers. By 16 days of development cells from the dermis have invaded the epidermis and may be found throughout the epidermis and on its surface. Among these cells are nerve fibres and Schwann cells as well as other unidentified cells. Antibodies directed against fibronectin bind to these abnormal groups of cells in the mutant epidermis and on its surface. A basal lamina, as determined by ultrastructure and by the immuno-fluorescent localization of laminin, was always found at the interface of the mutant epidermis and the invading cell population. By 19 days of development the mutant epidermis is thickened and is permeated by a network of cells including nerve fibres, Schwann cells, blood vessels, and collagen and fibronectin-secreting cells. A basal lamina always separates these groups of invading cells from the epidermal cell population.
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Yenmiş, Melodi, e Dinçer Ayaz. "The Story of the Finest Armor: Developmental Aspects of Reptile Skin". Journal of Developmental Biology 11, n.º 1 (28 de janeiro de 2023): 5. http://dx.doi.org/10.3390/jdb11010005.
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The reptile skin is a barrier against water loss and pathogens and an armor for mechanical damages. The integument of reptiles consists of two main layers: the epidermis and the dermis. The epidermis, the hard cover of the body which has an armor-like role, varies among extant reptiles in terms of structural aspects such as thickness, hardness or the kinds of appendages it constitutes. The reptile epithelial cells of the epidermis (keratinocytes) are composed of two main proteins: intermediate filament keratins (IFKs) and corneous beta proteins (CBPs). The outer horny layer of the epidermis, stratum corneum, is constituted of keratinocytes by means of terminal differentiation or cornification which is a result of the protein interactions where CBPs associate with and coat the initial scaffold of IFKs. Reptiles were able to colonize the terrestrial environment due to the changes in these epidermal structures, which led to various cornified epidermal appendages such as scales and scutes, a beak, claws or setae. Developmental and structural aspects of the epidermal CBPs as well as their shared chromosomal locus (EDC) indicate an ancestral origin that gave rise to the finest armor of reptilians.
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Foster, C. A., H. Yokozeki, K. Rappersberger, F. Koning, B. Volc-Platzer, A. Rieger, J. E. Coligan, K. Wolff e G. Stingl. "Human epidermal T cells predominantly belong to the lineage expressing alpha/beta T cell receptor." Journal of Experimental Medicine 171, n.º 4 (1 de abril de 1990): 997–1013. http://dx.doi.org/10.1084/jem.171.4.997.
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The epidermis of clinically normal-appearing human skin harbors a phenotypically heterogeneous population of T lymphocytes (TCs), the majority of which are CD2+/CD3+/CD5+ "memory" cells, but in an unactivated state, and express the TCR-alpha/beta. In contrast to murine skin, only a very minor subpopulation of CD3+ cells in the human epidermis bears the TCR-gamma/delta. Epidermal TCs primarily are distributed along the rete ridges in the basal keratinocyte layer and are often in close apposition to Langerhans cells (LCs). These TCs were propagated from epidermal cell suspensions after stimulation with TC activating agents (Con A, rIL-1, rIL-2), then evaluated for phenotypic features and TCR diversity. Similar to the in situ situation, most were CD4-/CD8+/TCR-alpha/beta+. In addition, two cultures contained TCR-gamma/delta+ cells; one of these determined to be an adherent CD4-/CD8+ population. Epidermal TCs were significantly (p less than 0.0001) more abundant in the sole than in the other body regions examined (i.e., 40 vs. 7 CD3+ cells/linear centimeter of epidermis) and seemed to have a particular affinity for the acrosyringial epithelium of eccrine sweat ducts. Moreover, the sole usually contained a greater number of CD8+ relative to CD4+ TCs, whereas the epidermal CD4/CD8 ratio in the trunk and extremities was quite variable, although the trend also was towards a slightly larger percentage of CD8+ cells. Collectively, our data suggest that the volar epidermis has a unique microenvironment which is responsible for both the higher density of TCs, preferentially CD8+, and lower number of LCs. This study has not only provided evidence for significant regional variability in the human epidermal TC population of normal skin, but also strengthens the concept for skin-associated lymphoid tissues (SALT), whereby memory TCs recirculate back to the epidermis and interact with resident antigen-presenting cells (i.e., LC).
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Liu, Lingxi, Mei Ju, Yu Hu, Chao Luan, Jiaan Zhang e Kun Chen. "Genome-wide DNA methylation and transcription analysis in psoriatic epidermis". Epigenomics 15, n.º 4 (fevereiro de 2023): 209–26. http://dx.doi.org/10.2217/epi-2022-0458.
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Aim: To identify DNA methylation and transcription biomarkers in the psoriatic epidermis. Materials & methods: Gene transcription and DNA methylation datasets of psoriatic epidermal tissue were obtained from the Gene Expression Omnibus. Machine learning algorithm analysis and weighted gene coexpression network analysis were carried out to screen hub genes. Results: Differentially methylated and expressed genes were identified in the psoriatic epidermis. Six hub genes were selected – GZMB, CRIP1, S100A12, ISG15, CRABP2 and VNN1 – whose transcript levels showed a significant correlation with Psoriasis Area and Severity Index scores and immune infiltration. Conclusion: Psoriatic epidermis is primarily in a hypermethylated status. Epidermis-specific hub differentially methylated and expressed genes are potential biomarkers to help judge the condition of psoriasis.
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Hisham majeed shlash. "Acomparative Anatomical Study of the Species Aster subulatus and Aster tripolium (Asteraceae) inTikrit- Iraq." Tikrit Journal of Pure Science 21, n.º 4 (7 de fevereiro de 2023): 30–35. http://dx.doi.org/10.25130/tjps.v21i4.1049.
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The two species Aster subulatus and Aster tripolium have been studied in the present study. It involves an anatomical study of epidermis of the leaf, the anatomical characters of diameters, and the numbers of epidermal cell stomata and Indumentum are found to be considerable in taxonomic value which separated and diagnostic both species. The abesence of the hairs on both sides upper and lower epidermis of the leaf have been showed. Also there are many differences in average of stomata numbers on both epidermis surfaces in both studied species. So the characters Also queditatie such as the shape and thickness of epidermis and the stomata are found to be with taxonomic value.
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Joye, Gary F., e Rex N. Paul. "Histology of Infection of Hydrilla verticillata by Macrophomina phaseolina". Weed Science 40, n.º 2 (junho de 1992): 288–95. http://dx.doi.org/10.1017/s0043174500057362.
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Infection of Hydrilla verticillata by Macrophomina phaseolina was investigated using scanning and transmission electron microscopy. Sprigs of plants in petri plates were inoculated with suspensions of fungal hyphae. Samples of inoculated and noninoculated plants were taken over time. Fungal cells attached to lower epidermal cell walls but not the upper epidermal cell walls of leaves. In less than 40 h, penetration through the cell wall was completed and colonization of host cells was observed. Penetration of upper epidermis was limited to the cell wall adjacent to a lower epidermal cell. No penetration was observed through the outer cell wall of upper epidermis. Inhibition of penetration through the outer cell wall of the upper epidermis may be attributable to an osmiophilic layer below the cell wall. Disruption of the host cell walls and subsequent host cell death was preceded by massive colonization of the host by this pathogen.
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Tsutsumi, O., Y. Kubota e T. Oka. "Effect of sialoadenectomy, treatment with epidermal growth factor (EGF) antiserum and replacement of EGF on the epidermis in mice". Journal of Endocrinology 113, n.º 2 (maio de 1987): 193—NP. http://dx.doi.org/10.1677/joe.0.1130193.
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ABSTRACT Epidermal growth factor (EGF) was present at a mean concentration of 266±18 (s.e.m.) pmol/mg wet tissue in the submandibular gland of 3-month-old male mice; it was also present in plasma at a concentration of 364±149 pmol/l. Sialoadenectomy (removal of the submandibular glands) decreased the plasma EGF content to undetectable levels (< 16·5 pmol/l), lowered the concentration of EGF in the skin from 1·22±0·11 to 0·47±0·08 fmol/mg wet tissue and reduced the thickness of the epidermis from 28·9±2·7 to 11·0±0·8 μm in 3 weeks (P < 0·001). Epidermal growth factor antiserum given to sialoadenectomized mice further decreased the thickness of the epidermis to 8·3 ±0·6 μm. No appreciable change was observed in the dermis and subcutaneous tissue. In sialoadenectomized mice, replacement of EGF prevented the decrease in thickness of the epidermis in a dose-dependent manner when started immediately after the operation. Treatment with EGF also effectively restored the normal morphology of the epidermis when its thickness had declined to its lowest level. These results suggest that EGF plays a physiological role in the maintenance of the epidermis. J. Endocr. (1987) 113, 193–197
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Elbe, A., E. Tschachler, G. Steiner, A. Binder, K. Wolff e G. Stingl. "Maturational steps of bone marrow-derived dendritic murine epidermal cells. Phenotypic and functional studies on Langerhans cells and Thy-1+ dendritic epidermal cells in the perinatal period." Journal of Immunology 143, n.º 8 (15 de outubro de 1989): 2431–38. http://dx.doi.org/10.4049/jimmunol.143.8.2431.
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Abstract The adult murine epidermis harbors two separate CD45+ bone marrow (BM)-derived dendritic cell systems, i.e., Ia+, ADPase+, Thy-1-, CD3- Langerhans cells (LC) and Ia-, ADPase-, Thy-1+, CD3+ dendritic epidermal T cells (DETC). To clarify whether the maturation of these cells from their ill-defined precursors is already accomplished before their entry into the epidermis or, alternatively, whether a specific epidermal milieu is required for the expression of their antigenic determinants, we studied the ontogeny of CD45+ epidermal cells (EC). In the fetal life, there exists a considerable number of CD45+, Ia-, ADPase+ dendritic epidermal cells. When cultured, these cells become Ia+ and, in parallel, acquire the potential of stimulating allogeneic T cell proliferation. These results imply that CD45+, Ia-, ADPase+ fetal dendritic epidermal cells are immature LC precursors and suggest that the epidermis plays a decisive role in LC maturation. The day 17 fetal epidermis also contains a small population of CD45+, Thy-1+, ADPase-, CD3- round cells. Over the course of 2 to 3 wk, they are slowly replaced by an ever increasing number of round and, finally, dendritic CD45+, Thy-1+, CD3+ EC. Thus, CD45+, Thy-1+, ADPase-, CD3- fetal EC may either be DETC precursors or, alternatively, may represent a distinctive cell system of unknown maturation potential. According to this latter theory, these cells would be eventually outnumbered by newly immigrating CD45+, Thy-1+, CD3+ T cells--the actual DETC.
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Pera, E., S. Stein e M. Kessel. "Ectodermal patterning in the avian embryo: epidermis versus neural plate". Development 126, n.º 1 (1 de janeiro de 1999): 63–73. http://dx.doi.org/10.1242/dev.126.1.63.
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Ectodermal patterning of the chick embryo begins in the uterus and continues during gastrulation, when cells with a neural fate become restricted to the neural plate around the primitive streak, and cells fated to become the epidermis to the periphery. The prospective epidermis at early stages is characterized by the expression of the homeobox gene DLX5, which remains an epidermal marker during gastrulation and neurulation. Later, some DLX5-expressing cells become internalized into the ventral forebrain and the neural crest at the hindbrain level. We studied the mechanism of ectodermal patterning by transplantation of Hensen's nodes and prechordal plates. The DLX5 marker indicates that not only a neural plate, but also a surrounding epidermis is induced in such operations. Similar effects can be obtained with neural plate grafts. These experiments demonstrate that the induction of a DLX5-positive epidermis is triggered by the midline, and the effect is transferred via the neural plate to the periphery. By repeated extirpations of the endoderm we suppressed the formation of an endoderm/mesoderm layer under the epiblast. This led to the generation of epidermis, and to the inhibition of neuroepithelium in the naked ectoderm. This suggests a signal necessary for neural, but inhibitory for epidermal development, normally coming from the lower layers. Finally, we demonstrate that BMP4, as well as BMP2, is capable of inducing epidermal fate by distorting the epidermis-neural plate boundary. This, however, does not happen independently within the neural plate or outside the normal DLX5 domain. In the area opaca, the co-transplantation of a BMP4 bead with a node graft leads to the induction of DLX5, thus indicating the cooperation of two factors. We conclude that ectodermal patterning is achieved by signalling both from the midline and from the periphery, within the upper but also from the lower layers.
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Çinar, Kenan, Mustafa Öztop e Emel Demirbağ. "The Histochemical Characterization of the Glycoconjugates in the Epidermal Mucous Cells of the Red Californian Earthworm, Eisenia foetida". Journal of Histology 2014 (3 de setembro de 2014): 1–6. http://dx.doi.org/10.1155/2014/130497.
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The aim of this study was to characterize the nature and regional distribution of the glycoconjugates secreted by epidermal mucous cells in Eisenia foetida (Annelida). Specimens were divided into six regions from anterior to posterior. The histochemistry was carried out by using standard histochemical methods. Histochemical staining properties of glycoconjugates in epidermal mucous cells were determined regionally. The epidermis of all regions contained strong to stronger PAS (+) cells in various degrees. The epidermis of the first, fourth, fifth, and sixth regions had strong to stronger AB pH 2.5 (+) cells. On the contrary, all regions contained weak to moderate AB pH 0.5 and AB pH 1.0 (+) cells. Most of mucous cells in epidermis of the first region contained both PAS (+) and AB (+) mucosubstances. All regions included weaker to weak AF (+) cells. All regions featured KOH/PAS (+) cells, with a slight reduction in reaction intensity in the epidermis of the last three regions. In this context, the different staining patterns observed in epidermal mucous cells hinted at their functional roles with respect to production of mucus with different physical properties. This study provided comprehensive information about the regional distribution patterns of the glycoconjugates and an opportunity to compare their distributional patterns in other annelids.
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Symonette, Caitlin J., Aman Kaur Mann, Xiao Cherie Tan, Cornelia Tolg, Jenny Ma, Francisco Perera, Arjang Yazdani e Eva A. Turley. "Hyaluronan-Phosphatidylethanolamine Polymers Form Pericellular Coats on Keratinocytes and Promote Basal Keratinocyte Proliferation". BioMed Research International 2014 (2014): 1–14. http://dx.doi.org/10.1155/2014/727459.
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Aged keratinocytes have diminished proliferative capacity and hyaluronan (HA) cell coats, which are losses that contribute to atrophic skin characterized by reduced barrier and repair functions. We formulated HA-phospholipid (phosphatidylethanolamine, HA-PE) polymers that form pericellular coats around cultured dermal fibroblasts independently of CD44 or RHAMM display. We investigated the ability of these HA-PE polymers to penetrate into aged mouse skin and restore epidermal function in vivo. Topically applied Alexa647-HA-PE penetrated into the epidermis and dermis, where it associated with both keratinocytes and fibroblasts. In contrast, Alexa647-HA was largely retained in the outer cornified layer of the epidermis and quantification of fluorescence confirmed that significantly more Alexa647-HA-PE penetrated into and was retained within the epidermis than Alexa647-HA. Multiple topical applications of HA-PE to shaved mouse skin significantly stimulated basal keratinocyte proliferation and epidermal thickness compared to HA or vehicle cream alone. HA-PE had no detectable effect on keratinocyte differentiation and did not promote local or systemic inflammation. These effects of HA-PE polymers are similar to those reported for endogenous epidermal HA in youthful skin and show that topical application of HA-PE polymers can restore some of the impaired functions of aged epidermis.