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Epidermal Cells (epidermal + cell)
Kinds of Epidermal Cells Terms modified by Epidermal Cells Selected AbstractsRELATIONSHIPS BETWEEN PRIMARY PLANT CELL WALL ARCHITECTURE AND MECHANICAL PROPERTIES FOR ONION BULB SCALE EPIDERMAL CELLSJOURNAL OF TEXTURE STUDIES, Issue 6 2004DAVID G. HEPWORTH ABSTRACT This article investigates onion epidermal tissue (Allium cepa) using a combination of mechanical testing, microscopy and modeling and relates tissue mechanical properties to the known structure of the cell walls. Onion epidermal tissue has a simple, regular structure of elongated cells, which have been used to enable the contributions to mechanical properties of cell walls and of higher order structures to be separated and analyzed. Two models of wall behavior were used to explore how Poisson's ratio of cell walls parallel to the plane of the epidermal surface may vary with applied strain. In the first model, cellulose microfibrils can be reorientated in an unrestricted way with the result that the cell wall volume decreases. In the second model the volume of the cell wall remains constant, which controls the reorientation of microfibrils, hence the Poisson's ratio. Measurements made from uniaxially stretched cells show that the data most closely fits model I, therefore, it is concluded that the bulk of the matrix has little influence on the observed mechanical properties (at a test rate of 1 mm/min), allowing cellulose microfibrils to reorient through the matrix in an unrestricted way during uniaxial tests. In its mechanical attributes the primary cell wall resembles more a knitted cloth than a semisolid composite material. When biaxial stretching is applied to tissue, so that there is no re-orientation of microfibrils, the cell wall material is still able to reach surprisingly large elastic strains of up to 12.5% and no plastic deformation was recorded. Current theory suggests that cellulose microfibrils can stretch elastically by a maximum of 7%, therefore further work is required to identify mechanisms that could account for the extra elastic strain. [source] Co-Culture of Mouse Epidermal Cells for Studies of PigmentationPIGMENT CELL & MELANOMA RESEARCH, Issue 2 2003Tae-Jin Yoon Interactions between melanocytes and keratinocytes in the skin suggest bi-directional interchanges between these two cell types. Thus, melanocytes cultured alone may not accurately reflect the physiology of the skin and the effects of physiological regulators in vivo, because they do not consider possible interactions with keratinocytes. As more and more pigment genes are identified and cloned, the characterization of their functions becomes more of a challenge, particularly with respect to their roles in the processing and transport of melanosomes and their transfer to keratinocytes. Immortalized melanocytes mutant at these loci are now being routinely generated from mice, but interestingly, successful co-culture of murine melanocytes and keratinocytes is very difficult compared with their human counterparts. Thus, we have now optimized co-culture conditions for murine melanocytes and keratinocytes so that pigmentation and the effects of specific mutations can be studied in a more physiologically relevant context. [source] Epidermal structures and stomatal parameters of Chinese endemic Glyptostrobus pensilis (Taxodiaceae)BOTANICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 2 2004QING-WEN MA Glyptostrobus pensilis K. Koch, the only living species, is endemic to southern China. Epidermal structures of G. pensilis have been studied on leaves collected from Guangzhou, southern China, the native locality of the species, and from Hangzhou, eastern China, the cultivated locality. Leaves are linear, linear-subulate and scale-like. Epidermal cells are rectangular and elongate parallel to the mid-vein on areas lacking stomata, and short, with rounded corners, on intrastomatal areas. Stomatal bands lie parallel to the mid-vein on both surfaces of leaves. Commonly the stomata have five or six subsidiary cells. Stomatal parameters (density and index) of the same surfaces of linear leaves from Guangzhou and Hangzhou show no statistically significant differences (P > 0.05). Considering the stomatal parameters of the same surfaces of linear-subulate leaves between the two localities, the stomatal index of the abaxial surfaces reveals no significant differences (P > 0.05), while the stomatal index of the adaxial surfaces and the stomatal density of both surfaces exhibit significant differences (P < 0.05). Intra-individual variation in stomatal index is smaller than that in stomatal density based on the coefficient of variability of stomatal parameters of the same areas of leaves. When studying the correlation between stomatal parameters of G. pensilis and atmospheric CO2 concentrations, the stomatal parameters of linear leaves are mostly significant, and stomatal index is more useful than stomatal density. © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society, 2004, 146, 153,162. [source] CD4 is expressed by epidermal Langerhans' cells predominantly as covalent dimersEXPERIMENTAL DERMATOLOGY, Issue 5 2003G. W. Lynch Abstract:, Langerhans' cells (LC) of skin are CD4 expressing, dendritic, antigen-presenting cells, that are essential for activation of primary immune responses and are productively infected by HIV. We have shown previously that lymphocytes and monocytes express CD4 both as monomers and covalently linked homodimers. In those cells the 55-kDa monomer structure predominates. LC in un-fractionated human epidermal cell (EC) suspension also expresses both forms of CD4, but in EC the dimer form is predominant. Because isolation of LC into single cell suspension by trypsin, as is routinely used for LC isolation, degrades CD4, a systematic study for an alternate procedure for LC isolation was performed. Thus it was found that collagenase blend F treatment can efficiently release LC into suspension, under conditions of only minimal degradation of control soluble recombinant CD4 or CEM-T4 or THP-1 cell CD4, or importantly of LC surface CD4. SDS,PAGE immunoblotting of purified LC extracted from EC by collagenase confirmed CD4 structure as predominantly 110-kDa dimers, with only minimal 55-kDa monomers. The suitability of LC prepared thus for functional studies was demonstrated with binding of functional ligand HIV gp120. It remains to be determined, however, why tissue embedded LC express mainly CD4 dimers, but single-celled blood lymphocytes and monocytes mainly monomers. [source] Secretory Cavity Development and Its Relationship with the Accumulation of Essential Oil in Fruits of Citrus medica L. var. sarcodactylis (Noot.) SwingleJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 5 2006She-Jian Liang Abstract The developmental types of secretory cavities in Citrus remain controversial. The relationship between secretory cavity development and the accumulation of essential oil in fruits of Citrus species is also unknown. In order to develop better insights into these problems, histological, histochemical, and cytochemical methods were used to investigate secretory cavity development and the accumulation of essential oil at different developmental stages of fruits of Citrus medica L. var. sarcodactylis (Noot.) Swingle. The results indicate that the secretory cavity of the variety seemed to originate from an epidermal cell and a subepidermal cell. These two cells underwent successive divisions, resulting in the formation of two parts: (i) a conical cap; and (ii) a globular gland. The formation of the lumen was schizolysigenous. Regular changes in the size of vacuoles and the accumulation of essential oil were revealed during the process of secretory cavity development. In addition, when fruits were a light yellow or golden color, the structure of secretory cavities was well developed and the content of essential oil in a single fruit reached a maximum. It would be most appropriate to collect the fruit as a medicinal material at this time. (Managing editor: Wei Wang) [source] Multivesicular compartments proliferate in susceptible and resistant MLA12 -barley leaves in response to infection by the biotrophic powdery mildew fungusNEW PHYTOLOGIST, Issue 3 2006Qianli An Summary ,,There is growing evidence that multivesicular bodies and cell wall-associated paramural bodies participate in the enhanced vesicle trafficking induced by pathogen attack. ,,Here, we performed transmission electron microscopy in combination with cytochemical localization of H2O2 to investigate multivesicular compartments during establishment of compatible interaction in susceptible barley (Hordeum vulgare) and during hypersensitive response in resistant MLA12 -barley infected by the barley powdery mildew fungus (Blumeria graminis f. sp. hordei). ,,Multivesicular bodies, intravacuolar vesicle aggregates and paramural bodies proliferated in the penetrated epidermal cell during development of the fungal haustorium. These vesicular structures also proliferated at the periphery of intact cells, which were adjacent to the hypersensitive dying cells and deposited cell wall appositions associated with H2O2 accumulation. All plasmodesmata between intact cells and hypersensitive cells were constricted or blocked by cell wall appositions. ,,These results suggest that multivesicular compartments participate in secretion of building blocks for cell wall appositions not only to arrest fungal penetration but also to contain hypersensitive cell death through blocking plasmodesmata. They may also participate in internalization of damaged membranes, deleterious materials, nutrients, elicitors and elicitor receptors. [source] Embryonic dermal condensation and adult dermal papilla induce hair follicles in adult glabrous epidermis through different mechanismsDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 2 2006Mutsumi Inamatsu Hair induction in the adult glabrous epidermis by the embryonic dermis was compared with that by the adult dermis. Recombinant skin, composed of the adult sole epidermis and the embryonic dermis containing dermal condensations (DC), was transplanted onto the back of nude mice. The epidermis of transplants formed hairs. Histology on the induction process demonstrated the formation of placode-like tissues, indicating that the transplant produces hair follicles through a mechanism similar to that underlying hair follicle development in the embryonic skin. An isolated adult rat sole skin piece, inserted with either an aggregate of cultured dermal papilla (DP) cells or an intact DP between its epidermis and dermis, was similarly transplanted. The transplant produced hair follicles. Histology showed that the epidermis in both cases surrounded the aggregates of DP cells. The epidermis never formed placode-like tissues. Thus, it was concluded that the adult epidermal cells recapitulate the embryonic process of hair follicle development when exposed to DC, whereas they get directly into the anagen of the hair cycle when exposed to DP. The expression pattern of Edar and Shh genes, and P-cadherin protein during the hair follicle development in the two types of transplants supported the above conclusion. [source] Ultrastructural identification of the antennal gland complement in Siagona europaea Dejean 1826, a myrmecophagous carabid beetleACTA ZOOLOGICA, Issue 3 2005Anita Giglio Abstract We examined antennal exocrine glands in adults of a myrmecophagous carabid beetle, Siagona europaea Dejean 1826 (Coleoptera, Carabidae), by light and electron microscopy and we identified two types of integumentary glands. The first type includes glands formed by three cells (a secretory cell, an intercalary cell and a duct cell) known as class 3 of Noirot and Quennedey (1991). The secretory cell has several large multivesicular electron-lucent bodies, indicating a glycoprotein product associated with lipids. We hypothesize that this secretion protects the surface of antennae and sensilla from wear. The second group of glands includes unicellular glands known as oenocytes (class 2 of Noirot and Quennedey, 1991), which secrete epicuticular hydrocarbons through epidermal cells. [source] Differentiation of the epidermis of scutes in embryos and juveniles of the tortoise Testudo hermanni with emphasis on beta-keratinizationACTA ZOOLOGICA, Issue 3 2005L. Alibardi Abstract The sequence of differentiation of the epidermis of scutes during embryogenesis in the tortoise Testudo hermanni was studied using autoradiography, electron microscopy and immunocytochemistry. The study was mainly conducted on the epidermis of the carapace, plastron and nail. Epidermal differentiation resembles that described for other reptiles, and the embryonic epidermis is composed of numerous cell layers. In the early stages of differentiation of the carapacial ridge, cytoplasmic blebs of epidermal cells are in direct contact with the extracellular matrix and mesenchymal cells. The influence of the dermis on the formation of the beta-layer is discussed. The dermis becomes rich in collagen bundles at later stages of development. The embryonic epidermis is formed by a flat periderm and four to six layers of subperidermal cells, storing 40,70-nm-thick coarse filaments that may represent interkeratin or matrix material. Beta-keratin is associated with the coarse filaments, suggesting that the protein may be polymerized on their surface. The presence of beta-keratin in embryonic epidermis suggests that this keratin might have been produced at the beginning of chelonian evolution. The embryonic epidermis of the scutes is lost around hatching and leaves underneath the definitive corneous beta-layer. Beneath the embryonic epidermis, cells that accumulate typical large bundles of beta-keratin appear at stage 23 and at hatching a compact beta-layer is present. The differentiation of these cells shows the progressive replacement of alpha-keratin bundles with bundles immunolabelled for beta-keratin. The nucleus is degraded and electron-dense nuclear material mixes with beta-keratin. In general, changes in tortoise skin when approaching terrestrial life resemble those of other reptiles. Lepidosaurian reptiles form an embryonic shedding layer and crocodilians have a thin embryonic epidermis that is rapidly lost near hacthing. Chelonians have a thicker embryonic epidermis that accumulates beta-keratin, a protein later used to make a thick corneous layer. [source] Correlation of fluorescence and electron microscopy of F-actin-containing sensory cells in the epidermis of Convoluta pulchra (Platyhelminthes: Acoela)ACTA ZOOLOGICA, Issue 1 2002R Pfistermüller Abstract Phalloidin-stained whole mounts of acoel turbellarians show brightly fluorescing club-shaped structures distributed over the epidermis and concentrated especially at the anterior and posterior tips of the body. By correlating electron micrographic images and fluorescence images of Convoluta pulchra, these structures can be seen to be sensory receptors with a central cilium surrounded by a collar of microvilli. The other candidate for showing fluorescence in the epidermis, namely gland necks, can be ruled out since their distribution is too dense to resemble the distribution of the fluorescent structures seen here. The collared sensory receptors were inserted between epidermal cells, and each bore a central cilium surrounded by a collar of 6,18 microvilli and an additional centrally positioned 2,7 microvilli of which 2 or 3 were associated with a modified rootlet called the swallow's nest. Confocal scanning laser microscopy resolved the core of actin filaments within the microvilli of the collar and their rootlet-like connections to the base of the sensory cell. Such receptors could also be identified by fluorescence microscopy in several other species of acoel turbellarians. [source] Host plant changes produced by the aphid Sipha flava: consequences for aphid feeding behaviour and growthENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 2 2002W.L. Gonzáles Abstract Induced plant responses may affect the behaviour and growth of the attacking herbivore insect. The aphid Sipha flava (Forbes) produces reddish spots on the infested leaf of its host plant Sorghum halepense (L.). In order to assess the consequences on the aphid of this presumptive induced plant response, we studied the feeding behaviour and growth of S. flava on previously infested and non-infested leaves of S. halepense. Considering that the reddish pigment could play a defensive role, its effect on aphid survival was determined in artificial diets. In addition, changes in the histology of the leaf and the chemical nature of the induced pigment were also studied. Aphids devoted a significantly shorter total time to non-penetration activities in infested than in non-infested leaves. Time before the first phloem ingestion tended to be shorter in infested leaves. The mean relative growth rate of S. flava nymphs was significantly higher on infested than on non-infested leaves. Survival of aphids on diet containing the reddish extract was not significantly different from that on the control diet. Infestation of S. halepense by S. flava produced a reddish coloration in the leaf, which was identified as an anthocyanin by UV-visible spectrometry. Light microscopy showed that only mesophyll cells of previously infested plants presented swelled, dispersed, and heterogeneously stained chloroplasts with a higher accumulation of starch granules, no grana arranged in stacks, and reduction in the amount of inner membranes (thylakoids), relatively to chloroplasts of non-infested leaves. Scanning electron micrographs of leaf surface revealed reduced presence of crystalline epicuticular waxes of epidermal cells in infested leaves as compared to non-infested ones. The main conclusion is that the attack of S. flava to S. halepense leaves induced plant susceptibility where aphid feeding behaviour and growth were both enhanced on previously infested leaves. [source] Two similar enhanced root-colonizing Pseudomonas strains differ largely in their colonization strategies of avocado roots and Rosellinia necatrix hyphaeENVIRONMENTAL MICROBIOLOGY, Issue 12 2008Clara Pliego Summary Pseudomonas alcaligenes AVO73 and Pseudomonas pseudoalcaligenes AVO110 were selected previously as efficient avocado root tip colonizers, displaying in vitro antagonism towards Rosellinia necatrix, causal agent of avocado white root rot. Despite the higher number of antagonistic properties shown in vitro by AVO73, only AVO110 demonstrated significant protection against avocado white root rot. As both strains are enhanced root colonizers, and as colonization is crucial for the most likely biocontrol mechanisms used by these strains, namely production of non-antibiotic antifungal compounds and competition for nutrients and niches, we decided to compare the interactions of the bacterial strains with avocado roots as well as with R. necatrix hyphae. The results indicate that strain AVO110 is superior in biocontrol trait swimming motility and establishes on the root tip of avocado plants faster than AVO73. Visualization studies, using Gfp-labelled derivatives of these strains, showed that AVO110, in contrast to AVO73, colonizes intercellular crevices between neighbouring plant root epidermal cells, a microhabitat of enhanced exudation. Moreover, AVO110, but not AVO73, also colonizes root wounds, described to be preferential penetration sites for R. necatrix infection. This result strongly suggests that AVO110 meets, and can attack, the pathogen on the root. Finally, when co-inoculated with the pathogen, AVO110 utilizes hyphal exudates more efficiently for proliferation than AVO73 does, and colonizes the hyphae more abundantly than AVO73. We conclude that the differences between the strains in colonization levels and strategies are likely to contribute to, and even can explain, the difference in disease-controlling abilities between the strains. This is the first report that shows that two similar bacterial strains, selected by their ability to colonize avocado root, use strongly different root colonization strategies and suggests that in addition to the total bacterial root colonization level, the sites occupied on the root are important for biocontrol. [source] Silencing of an abdominal Hox gene during early development is correlated with limb development in a crustacean trunkEVOLUTION AND DEVELOPMENT, Issue 2 2010Cheryl C. Hsia SUMMARY We tested whether Artemia abd-A could repress limbs in Drosophila embryos, and found that although abd-A transcripts were produced, ABD-A protein was not. Similarly, developing Artemia epidermal cells showed expression of abd-A transcripts without accumulation of ABD-A protein. This finding in Artemia reveals a new variation in Hox gene function that is associated with morphological evolution. In this case, a HOX protein expression pattern is completely absent during early development, although the HOX protein is expressed at later stages in the central nervous system in a "homeotic-like" pattern. The combination of an absence of ABD-A protein expression in the Artemia limb primordia and the weak repressive function of Artemia UBX protein on the limb-promoting gene Dll are likely to be two reasons why homonomous limbs develop throughout the entire Artemia trunk. [source] Expression of the human Cathepsin L inhibitor hurpin in mice: skin alterations and increased carcinogenesisEXPERIMENTAL DERMATOLOGY, Issue 9 2007Markus Walz Abstract:, The serine protease inhibitor (serpin) hurpin (serpin B13) is a cross class-specific inhibitor of the cysteine protease Cathepsin (Cat) L. Cat L is involved in lysosomal protein degradation, hair follicle morphogenesis, epidermal differentiation and epitope generation of antigens. Hurpin is a 44 kDa protein which is expressed predominantly in epidermal cells. In psoriatic skin samples, hurpin was strongly overexpressed when compared with normal skin. Keratinocytes overexpressing hurpin showed increased resistance towards UVB-induced apoptosis. To further analyse the functional importance of this inhibitor, we have generated transgenic mice with deregulated Cat L activity by expressing human hurpin in addition to the endogenous mouse inhibitor. The three independent transgenic lines generated were characterized by identical effects excluding insertional phenotypes. Macroscopically, mice expressing human hurpin are characterized by abnormal abdominal fur. The number of apoptotic cells and caspase-3 positive cells was reduced after UV-irradiation in transgenic animals compared with wild-type mice. Interestingly, after chemical carcinogenesis, transgenic mice showed an increased susceptibility to develop skin cancer. Array analysis of gene expression revealed distinct differences between wild-type and hurpin-transgenic mice. Among others, differentially expressed genes are related to antigen presentation and angiogenesis. These results suggest an important role of Cat L regulation by hurpin which might be of clinical relevance in human skin diseases. [source] Effective inhibition of melanosome transfer to keratinocytes by lectins and niacinamide is reversibleEXPERIMENTAL DERMATOLOGY, Issue 7 2005Amanda Greatens Abstract:, Skin pigmentation results in part from the transfer of melanized melanosomes synthesized by melanocytes to neighboring keratinocytes. Plasma membrane lectins and their glycoconjugates expressed by these epidermal cells are critical molecules involved in this transfer process. In addition, the derivative of vitamin B3, niacinamide, can inhibit melanosome transfer and induce skin lightening. We investigated the effects of these molecules on the viability of melanocytes and keratinocytes and on the reversibility of melanosome-transfer inhibition induced by these agents using an in vitro melanocyte,keratinocyte coculture model system. While lectins and neoglycoproteins could induce apoptosis in a dose-dependent manner to melanocytes or keratinocytes in monoculture, similar dosages of the lectins, as opposed to neoglycoproteins, did not induce apoptosis to either cell type when treated in coculture. The dosages of lectins and niacinamide not affecting cell viability produced an inhibitory effect on melanosome transfer, when used either alone or together in cocultures of melanocytes,keratinocytes. Cocultures treated with lectins or niacinamide resumed normal melanosome transfer in 3 days after removal of the inhibitor, while cocultures treated with a combination of lectins and niacinamide demonstrated a lag in this recovery. Subsequently, we assessed the effect of niacinamide on facial hyperpigmented spots using a vehicle-controlled, split-faced design human clinical trial. Topical application of niacinamide resulted in a dose-dependent and reversible reduction in hyperpigmented lesions. These results suggest that lectins and niacinamide at concentrations that do not affect cell viability are reversible inhibitors of melanosome transfer. [source] Connections between nerve endings and epidermal cells: are they synapses?EXPERIMENTAL DERMATOLOGY, Issue 1 2004Yannick Chateau Abstract: Based on electron microscopy and confocal scanning microscopy, contacts between sensory axons and the cells of the epidermis have been described: with keratinocytes, Langerhans cells, melanocytes and Merkel cells. We would like to initiate a debate on this question: "Are neuro-epidermal connections synapses?". Anatomically, neuro-epidermal junctions can be considered as synapses in our opinion. If neuro-epidermal junctions are synapses, they probably belong to the family of en passant synapses, with nerve endings passing along epidermal cells and occasionally connecting to them. In conclusion, we suggest that neuro-epidermal junctions could be considered as true synapses, but this does not exclude non synaptic interactions. [source] In vivo UVB irradiation induces clustering of Fas (CD95) on human epidermal cellsEXPERIMENTAL DERMATOLOGY, Issue 6 2003Bo Bang Abstract:,In vitro studies with human cell lines have demonstrated that the death receptor Fas plays a role in ultraviolet (UV)-induced apoptosis. The purpose of the present study was to investigate the relation between Fas expression and apoptosis as well as clustering of Fas in human epidermis after a single dose of UVB irradiation. Normal healthy individuals were irradiated with three minimal erythema doses (MED) of UVB on forearm or buttock skin. Suction blisters from unirradiated and irradiated skin were raised, and Fas, FasL, and apoptosis of epidermal cells were quantified by flow cytometry. Clustering of Fas was demonstrated by confocal laser scanning microscopy on cryostat sections from skin biopsies. Soluble FasL in suction blister fluid was quantified by ELISA. Flow cytometric analysis demonstrated increased expression intensity of Fas after irradiation, with 1.6-, 2.2- and 2.7-fold increased median expression at 24, 48 and 72 h after irradiation, respectively (n = 4). Apoptosis was demonstrated by the TUNEL reaction, and the maximum of apoptotic cells was detected at 48 h after irradiation. Double-staining for Fas and TUNEL showed that apoptosis was restricted to the Fas-positive epidermal subpopulation, but there was no correlation between the intensities of Fas expression and TUNEL reaction. Median expression intensity of FasL-positive cells transiently decreased to 0.9- and 0.8-fold of the preirradiation respective level after 24 h and 48 h, respectively, and returned to the respective preirradiation level at 72 h after irradiation (n = 4). Concentrations of soluble FasL in suction blister fluid from UVB-irradiated skin did not differ from those in unirradiated skin (n = 5). Confocal laser scanning microscopy showed a rapid clustering of Fas within 30 min after irradiation. A simultaneous clustering of the adapter signalling protein FADD suggested that Fas clustering has a functional significance. Our results are in accordance with previous findings from in vitro studies, and suggest that Fas is activated in vivo in human epidermis after UVB exposure. [source] Serum-free cultured keratinocytes fail to organize fibronectin matrix and possess different distribution of beta-1 integrinsEXPERIMENTAL DERMATOLOGY, Issue 2 2001G. Altankov Abstract: The development of serum free medium formulation for culturing keratinocytes was a breakthrough in achieving a high number of epidermal cells for experimental and therapeutic studies, in particular to support the wound healing process. It is not clear, however, if switching the cells to highly proliferative phenotype may reflect change in other cellular functions important for the wound repair as their adhesive interactions with the extracellular matrix components. Remodelling of the extracellular matrix, particularly of fibronectin plays an essential role for guiding the cells during wound healing. The molecular mechanisms for organization of this provisional fibronectin matrix, however, are still not clear. We found that keratinocytes in serum containing medium, although in fewer numbers than fibroblasts, were able to remove adsorbed fluorescent labelled fibronectin from the substratum and reorganize it in a fibrilar pattern along the cell periphery. After 3 days the secreted fibronectin had also been organized as matrix-like fibers and as clusters deposited on the substratum after migrating cells. In contrast, serum free cultured keratinocytes fail to organize pre-adsorbed fluorescent labelled fibronectin, as well as the secreted fibronectin, although they grow very well under these conditions. Switching the cells to serum containing medium initiates the removal of fluorescent labelled fibronectin from the substratum, however without reorganization in fibrillar pattern. Most likely, these keratinocytes remove fluorescent labelled fibronectin by the expression of proteolytic activity, rather than with the mechanical function of ,1 integrins. The latter were diffusely dispersed in serum containing conditions and tend to organize in focal adhesions in serum free cultured cells. We assumed their transient expression and different affinity state might be important for the keratinocyte migration and matrix assembly mechanism. [source] Solar-simulating irradiation of the skin of human subjects in vivo produces Langerhans cell responses distinct from irradiation ex vivo and in vitroEXPERIMENTAL DERMATOLOGY, Issue 4 2000J. K. Laihia Abstract: It has been postulated that Langerhans cells (LC) provide tolerogenic signals in the local impairment of cutaneous immune functions and antigen-specific tolerance induced by UV radiation. Studies in vitro and ex vivo have indicated that UV radiation may down-regulate the expression of costimulatory molecules on LC, leading to reduced antigen-presenting function. In contrast, we recently observed an up-regulatory stage in the number of human epidermal LC with induced expression of B7 costimulatory molecules 12,24 h after solar-simulating UV radiation (SSR) in vivo. To examine the apparent discrepancy between the observed human LC responses in vitro, ex vivo and in vivo, we compared the three protocols in a parallel fashion. The intact skin as well as skin explants and epidermal cell suspensions from the same individuals were irradiated with a single erythematogenic dose of SSR. The expression of cell surface markers in the epidermal cells was analysed with flow cytometry 24 h later. The number of CD1a+/HLA-DR+ LC increased post-SSR in vivo by a factor of 2.8±0.4, whereas in irradiated skin explants ex vivo or in cell suspensions in vitro, reduced numbers were seen. HLA-DR expression intensities were found to have increased on DR+ and CD1a+/DR+ cells in vivo. Similarly, SSR induced B7-2 (CD86) expression in CD1a+ cells significantly in vivo (P=0.031) but reduced the expression ex vivo or in vitro. We conclude that the early up-regulatory stage of human LC number and membrane markers, recorded at 24 h after a single exposure to SSR, is exclusively an in vivo phenomenon. [source] Vanadium-induced apoptosis of HaCaT cells is mediated by c-fos and involves nuclear accumulation of clusterinFEBS JOURNAL, Issue 14 2009Soultana Markopoulou Vanadium exerts a variety of biological effects, including antiproliferative responses through activation of the respective signaling pathways and the generation of reactive oxygen species. As epidermal cells are exposed to environmental insults, human keratinocytes (HaCaT) were used to investigate the mechanism of the antiproliferative effects of vanadyl(IV) sulfate (VOSO4). Treatment of HaCaT cells with VOSO4 inhibited proliferation and induced apoptosis in a dose-dependent manner. Inhibition of proliferation was associated with downregulation of cyclins D1 and E, E2F1, and the cyclin-dependent kinase inhibitors p21Cip1/Waf1 and p27Kip1. Induction of apoptosis correlated with upregulation of the c-fos oncoprotein, changes in the expression of clusterin (CLU), an altered ratio of antiapoptotic to proapoptotic Bcl-2 protein family members, and poly(ADP-ribose) polymerase-1 cleavage. Forced overexpression of c-fos induced apoptosis in HaCaT cells that correlated with secretory CLU downregulation and upregulation of nuclear CLU (nCLU), a pro-death protein. Overexpression of Bcl-2 protected HaCaT cells from vanadium-induced apoptosis, whereas secretory CLU overexpression offered no cytoprotection. In contrast, nCLU sensitized HaCaT cells to apoptosis. Our data suggest that vanadium-mediated apoptosis was promoted by c-fos, leading to alterations in CLU isoform processing and induction of the pro-death nCLU protein. [source] Expression of MsPG3-GFP fusions in Medicago truncatula,hairy roots' reveals preferential tip localization of the protein in root hairsFEBS JOURNAL, Issue 2 2003Ignacio D. Rodríguez-Llorente Tip growth is a specialized type of polar growth where new cell wall is deposited in a localized region of the cell, the growing tip. These cells show a characteristic zonation, with a high accumulation of secretory vesicles containing cell wall components at the tip, followed by an organelle-enriched zone. MsPG3 is a Medicago sativa polygalacturonase gene isolated in our laboratory, specifically expressed during the interaction of this plant with its symbiotic partner Sinorhizobium meliloti and which might participate in tip growth processes during symbiosis. We have used MsPG3-GFP fusions to study in vivo protein transport processes and localization during root hair growth. Different MsPG3-GFP fusions were expressed in Medicago truncatula,hairy roots' following a protocol developed for this study and also tested by transient expression in onion epidermal cells. Preferential accumulation of an MsPG3-GFP fusion protein in the tip of the growing root hair at different developmental stages was found, confirming the delivery of MsPG3 to the newly synthesized cell wall. This indicates that this protein may participate in tip growth processes during symbiosis and, in addition, that this fusion could be a useful tool to study this process in plants. [source] Ericoid mycorrhizal fungi are common root inhabitants of non- Ericaceae plants in a south-eastern Australian sclerophyll forestFEMS MICROBIOLOGY ECOLOGY, Issue 2 2008Susan M. Chambers Abstract Fungi were isolated from the roots of 17 plant species from the families Apiaceae, Cunoniaceae, Cyperaceae, Droseraceae, Fabaceae-Mimosoideae, Lomandraceae, Myrtaceae, Pittosporaceae, Proteaceae and Stylidiaceae at a sclerophyll forest site in New South Wales, Australia. Internal transcribed spacer (ITS) restriction fragment length polymorphism (RFLP) and sequence comparisons indicated that the isolated fungi had affinities to a range of ascomycetes, basidiomycetes and zygomycetes. Four RFLP types had closest affinities to previously identified Helotiales ericoid mycorrhizal (ERM) or Oidiodendron spp. Isolates representing six RFLP types, which were variously isolated from all 17 plant species, formed ERM coils in hair root epidermal cells of Woollsia pungens (Ericaceae) under gnotobiotic conditions. Three of these isolates formed intercellular hyphae, intracellular hyphae and/or microsclerotia, which are typical of dark septate endophyte infection, in roots of Stylidium productum (Stylidiaceae), indicating an ability to form different types of association with roots of different hosts. Overall the data indicate that a broad range of plant taxa may act as repositories for ERM fungi in sclerophyll forest soil. [source] The development and endophytic nature of the fungus Heteroconium chaetospiraFEMS MICROBIOLOGY LETTERS, Issue 2 2005Teruyoshi Hashiba Abstract The root endophytic fungus Heteroconium chaetospira was isolated from roots of Chinese cabbage grown in field soil in Japan. This fungus penetrates through the outer epidermal cells of its host, passes into the inner cortex, and grows throughout the cortical cells, including those of the root tip region, without causing apparent pathogenic symptoms. There are no ultrastructural signs of host resistance responses. H. chaetospira has been recovered from 19 plant species in which there was no disruption of host growth. H. chaetospira has a symbiotic association with Chinese cabbage. The fungus provides nitrogen in exchange for carbon. These associations are beneficial for the inoculated plants, as demonstrated by increased growth rate. When used as a preinoculum, H. chaetospira suppresses the incidence of clubroot and Verticillium yellows when the test plant is post-inoculated with the causal agents of these diseases. H. chaetospira is an effective biocontrol agent against clubroot in Chinese cabbage at a low to moderate soil moisture range and a pathogen resting spore density of 105 resting spores per gram of soil in situ. Disease caused by Pseudomonas syringae pv. macricola and Alternaria brassicae on leaves can be suppressed by treatment with H. chaetospira. The fungus persists in the roots and induces systemic resistance to the foliar disease. [source] EMBRYO YELLOW gene, encoding a subunit of the conserved oligomeric Golgi complex, is required for appropriate cell expansion and meristem organization in Arabidopsis thalianaGENES TO CELLS, Issue 6 2008Takaaki Ishikawa We identified an embryo yellow (eye) mutation in Arabidopsis that leads to the abnormal coloration and morphology of embryos. The eye mutant formed bushy plants, with aberrant organization of the shoot apical meristem (SAM) and unexpanded leaves with irregular phyllotaxy. The epidermal cells of the eye mutant were much smaller than that of the wild-type. Thus, EYE is required for expansion of cells and organs, and for formation of the organized SAM. Hydrophobic layers of epidermal cells were also disrupted, suggesting that EYE might be involved in the generation of the extra-cellular matrix. The mutated gene encoded a protein that is homologous to Cog7, a subunit of the conserved oligomeric Golgi (COG) complex, which is required for the normal morphology and function of the Golgi appratus. The eye mutation caused mislocalization of a Golgi protein. In addition, the size of the Golgi apparatus was also altered. Thus, EYE might be involved in transport or retention of Golgi-localized proteins and in maintenance of Golgi morphology. We propose that some Golgi-localized proteins, distributions of which are controlled by EYE, play important roles in expansion of cells and organs, and in formation of the properly organized SAM in plants. [source] Dyskeratosis congenita with isolated neutropenia and granulocyte colony-stimulating factor treatmentINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 3 2002Kutluhan Yilmaz A 3-year-old Turkish boy with a history of chronic cough, recurrent bronchopneumonia, and a borderline sweat chloride test (40 mEq/L) was referred for further evaluation to our department. He was born at term (2100 g) to a marriage with no consanguinity. His mother and father were 40 and 46 years old, respectively. Physical examination (Fig. 1) revealed hypopigmented, atrophic, and hyperkeratotic skin lesions surrounded by reticulate hyperpigmentation on the entire body, predominantly on the face, neck, arms, shoulders, and legs, which had been noticed initially at the age of 18 months. Dystrophic toenails, sparse and thin hair, and phimosis were also observed. Laboratory tests disclosed an isolated neutropenia (white blood cell count, 1800/mm3). Bone marrow (BM) aspiration showed a decreased myelopoiesis without myelodysplastic changes, but normal erythropoiesis, megakaryopoiesis, and normal stroma. Lymphocyte subgroups containing CD4, CD5, CD6, CD8, CD19, CD23, and CD25, and immunoglobulin G (IgG), IgM, IgA, and IgE, were in the normal range; hemoglobin F (HbF), 2.8%. Spontaneous and clastogen-induced chromosome breaks were not increased. A skin biopsy showed increased pigmentation at the basal layer, dyskeratotic epidermal cells, and marked IgM deposition and cytoid bodies and mild IgA and IgG deposits at the dermo-epidermal junction. Lactate response to glucose challenge, amino acid chromatography, and urine organic acid analysis were normal. Figure 1. Hypopigmented, atrophic, and hyperkeratotic skin lesions surrounded by reticulate hyperpigmentation involving predominantly the face, neck, arms, shoulders, and legs, dystrophic toenails, and sparse and thin hair A diagnosis of dyskeratosis congenita (DC) was made with typical skin lesions, dystrophic toenails, thin and sparse hair, and neutropenia with decreased myelopoiesis in BM. Treatment with granulocyte colony-stimulating factor (G-CSF) was considered for the neutropenia. As the increase in neutrophil count at a dose of 5 µg/kg was not adequate, 10 µg/kg G-CSF was tried (Fig. 2). With 10 µg/kg once to three times a week, a 1.8,4.8-fold increase in the absolute neutrophil count (ANC) was achieved with no side-effects. Treatment was more frequent during infection (days 22,28). Figure 2. Response of absolute neutrophil count (ANC) to granulocyte colony-stimulating factor (G-CSF) administration (5 µg/kg on days 1 and 3; 10 µg/kg on days 5, 10, 16, 23, 26, 28, 34, 40, 48, 54) [source] Eccrine poroma of the heelINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 6 2000Harvey Lemont A 67-year-old African,American woman had a tender red nodule on the posterior aspect of her left heel of 20 years' duration. The lesion had initially grown quickly to its present size, but subsequently remained unchanged through the years. No previous history of trauma to the area could be elicited. The lesion was not tender or painful, although the patient related some recent discomfort when wearing shoes with high heel counters. Examination revealed a soft, multilobulated, skin-colored nodule, measuring approximately 1.1 cm at its greatest diameter ( Fig. 1), with a rim space or moat ( Fig. 2) surrounding the lesion. Biopsy of the lesion demonstrated a uniform proliferation of basaloid cells exhibiting a sharp demarcation between the adjacent normal epidermis ( Fig. 3). No horn cysts were present. The papillary dermis demonstrated multiple ectatic blood vessels ( Fig. 4) which may be responsible for its reddish appearance. Figure 1 Multilobulated,. red, granulating lesion on the posterior heel Figure 2 Note. the characteristic ,,moat'' surrounding the lesion Figure 3 Biopsy. reveals a proliferation of uniformly small cuboidal cells sharply demarcated from the adjacent normal epidermal cells Figure 4 Ectatic. vessel dilatation most likely responsible for the reddish color of the lesion [source] Ciliary ultrastructure of neomeniomorphs (Mollusca, Neomeniomorpha = Solenogastres)INVERTEBRATE BIOLOGY, Issue 4 2001Kennet Lundin Abstract. The ultrastructure of the ciliary apparatus of multiciliated epidermal cells of the trochophore of Epimenia babai and the adult of Strophomenia scandens was studied. The trochal cirri of E. babai consists of long cilia with unspecialized tips. The surfaces between the trochs are sparsely covered with shorter cilia of similar structure except for length. In the adult of S. scandens, the foot is covered by a dense mat of cilia with blunt electron-dense tips. In both E. babai and S. scandens, all cilia have two perpendicularly orientated rootlets. This condition is similar to that of the Chaetodermomorpha (=Caudofoveata) and Polyplacophora. In other molluscs studied to date, the cilia of multiciliated epidermal cells have a single rootlet or a derivative thereof. The presence of two ciliary rootlets likely represents the basal plesiomorphic state for the Bilateria. The existence of this character in the Neomeniomorpha, Chaetodermomorpha, and Polyplacophora is congruent with the hypothesis of a basal position of these taxa within the Mollusca. [source] Expression of beta-keratin mRNAs and proline uptake in epidermal cells of growing scales and pad lamellae of gecko lizardsJOURNAL OF ANATOMY, Issue 1 2007Lorenzo Alibardi Abstract Beta-keratins form a large part of the proteins contained in the hard beta layer of reptilian scales. The expression of genes encoding glycine,proline-rich beta-keratins in normal and regenerating epidermis of two species of gecko lizards has been studied by in situ hybridization. The probes localize mRNAs in differentiating oberhautchen and beta cells of growing scales and in modified scales, termed pad lamellae, on the digits of gecko lizards. In situ localization at the ultrastructural level shows clusters of gold particles in the cytoplasm among beta-keratin filaments of oberhautchen and beta cells. They are also present in the differentiating elongation or setae of oberhautchen cells present in pad lamellae. Setae allow geckos to adhere and climb vertical surfaces. Oberhautchen and beta cells also incorporate tritiated proline. The fine localization of the beta-keratin mRNAs and the uptake of proline confirms the biomolecular data that identified glycine,proline-rich beta-keratin in differentiating beta cells of gecko epidermis. The present study also shows the presence of differentiating and metabolically active cells in both inner and outer oberhautchen/beta cells at the base of the outer setae localized at the tip of pad lamellae. The addition of new beta and alpha cells to the corneous layer near the tip of the outer setae explains the anterior movement of the setae along the apical free-margin of pad lamellae. The rapid replacement of setae ensures the continuous usage of the gecko's adhesive devices, the pad lamellae, during most of their active life. [source] Internalization of bioluminescent Escherichia coli and Salmonella Montevideo in growing bean sproutsJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2003K. Warriner Abstract Aims: Investigate the interaction of bioluminescent Escherichia coli and Salmonella Montevideo with germinating mung bean sprouts. Methods and Results:E. coli or Salm. Montevideo introduced on mung beans became established both internally and externally on sprouts after the initial 24 h germinating period. In both cases the inoculated bacterium formed the predominant microflora on the sprouted beans throughout. From the bioluminescent profile of inoculated sprouting beans, bacterial growth was found to be in close proximity to the roots but not on the hypocotyls. Clumps (biofilms) of cells with low viability were observed within the grooves between epidermal cells on hypocotyls. Treatment with 20 000 ppm sodium hypochlorite removed the majority of bacteria from the surface of hypocotyls although nonviable single cells were occasionally observed. However, viable bacteria were recovered from the apoplastic fluid, and extracts of surface-sterilized sprouts indicating that the internal bacterial populations had been protected. This was confirmed using in situ , -glucuronidase staining of surface-sterilized sprouts where cleaved enzyme substrate (by the action of internalized E. coli) was visualized within the plant vascular system. Conclusions:E. coli or Salmonella present on seeds become internalized within the subsequent sprouts and cannot be removed by postharvest biocidal washing. Significance and Impact of the Study: Mung bean production should be carefully controlled to prevent contamination occurring in order to minimize the health risk associated with raw bean sprouts. [source] Insulin receptor substrate 1 (IRS-1) plays a unique role in normal epidermal physiology,JOURNAL OF CELLULAR PHYSIOLOGY, Issue 2 2007Marianna Sadagurski Insulin receptor substrate (IRS) proteins play a central role in insulin signaling. Previously we have demonstrated that insulin is essential for normal skin development and function. In the present study we investigated the involvement of the IRS-1 and IRS-2 proteins in skin physiology and in mediating insulin action in skin. For this purpose we have investigated the effects of inactivation of each of the IRSs on skin, studying skin sections and primary skin cells derived from IRS-1 or IRS-2 null mice. We have demonstrated that while the skin of the IRS-2 null mice appeared normal, the skin of the IRS-1 null mice was thinner and translucent. Histological analysis revealed that the thinning of the IRS-1 null skin was a consequence of the thinning of the spinous compartment, consisting of fewer layers. Proliferation of the IRS-1 and IRS-2 null skin epidermal cells was normal. However, the differentiation process of the IRS-1 skin and skin cells was impaired. There was a marked decrease in the induction of the expression of K1, the marker of advanced stages of skin differentiation. In contrary, IRS-2 inactivation had no effects on skin differentiation. In conclusion, we have shown for the first time that IRS-1 but not IRS-2 has an effect on skin formation and development, being one of the main activators of the differentiation process in skin keratinocytes. Furthermore, we suggest that IRS-1 and IRS-2 have distinct roles in skin physiology. J. Cell. Physiol. 213: 519,527, 2007. © 2007 Wiley-Liss, Inc. [source] | ||||||||||||||||||||||||||||||||||