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Cortical Cells (cortical + cell)
Kinds of Cortical Cells Selected AbstractsHydroclathrus (Scytosiphonaceae, Phaeophyceae): Conspectus of the genus and proposal of new species from Australia and HawaiiPHYCOLOGICAL RESEARCH, Issue 4 2003Gerald T. Kraft SUMMARY Representatives of the two current species of Hydroclathrus, Hydroclathrus clathratus (C. Agardh) Howe (the generitype) and Hydroclathrus tenuis Tseng et Lu, are compared to recent collections of the genus from isolated localities in the central and south Pacific: Necker Island and Lord Howe Island, respectively. Although published descriptions of the virtually pan-tropical/warm-temperate H. clathratus portray a species highly variable in the habits and soral distribution patterns of the macro-phases of its life history, our observations support the hypothesis that the newly discovered Pacific island populations represent new species. Hydroclathrus steph-anosorus Kraft, sp. nov., from Lord Howe Island, differs from seemingly typical H. clathratus by the low-domed profiles of its surface cortical cells, aggregates of moniliform hair primordia that are almost always associated with plurangial sori, and particularly by the configurations of the sori themselves, which form discrete, nearly circular rings around the central hair tufts. Hydroclathrus tumulis Kraft et Abbott, sp. nov., from two deep-water localities in the northwestern Hawaiian Islands, has subacutely papillate cortical cells, scattered single, paired or laxly aggregated hair primordia of distinctive obcuneate morphology, and discrete, angular plurangial sori with no predetermined relationship to hairs, the plurangia being relatively laxly aggregated by virtue of their often arising on pedicels formed by the peaked crests of the cortical bearing cells. H. tenuis, although making the most striking visual impression of any of the species because of its exceedingly narrow, fibrous membranes, seems otherwise closest to H. clathratus in cortical cell, hair and soral features, absolute morphological boundaries between the two species being perhaps difficult to draw at times. [source] Neocortical Potassium Currents Are Enhanced by the Antiepileptic Drug LamotrigineEPILEPSIA, Issue 7 2002Cristina Zona Summary: ,Purpose: We used field-potential recordings in slices of rat cerebral cortex along with whole-cell patch recordings from rat neocortical cells in culture to test the hypothesis that the antiepileptic drug (AED) lamotrigine (LTG) modulates K+ -mediated, hyperpolarizing currents. Methods: Extracellular field-potential recordings were performed in neocortical slices obtained from Wistar rats aged 25,50 days. Rat neocortical neurons in culture were subjected to the whole-cell mode of voltage clamping under experimental conditions designed to study voltage-gated K+ currents. Results: In the in vitro slice preparation, LTG (100,400 ,M) reduced and/or abolished epileptiform discharges induced by 4-aminopyridine (4AP, 100 ,M; n = 10), at doses that were significantly higher than those required to affect epileptiform activity recorded in Mg2+ -free medium (n = 8). We also discovered that in cultured cortical cells, LTG (100,500 ,M; n = 13) increased a transient, 4AP-sensitive, outward current elicited by depolarizing commands in medium containing voltage-gated Ca2+ and Na+ channel antagonists. Moreover, we did not observe any change in a late, tetraethylammonium-sensitive outward current. Conclusions: Our data indicate that LTG, in addition to the well-known reduction of voltage-gated Na+ currents, potentiates 4AP-sensitive, K+ -mediated hyperpolarizing conductances in cortical neurons. This mechanism of action contributes to the anticonvulsant effects exerted by LTG in experimental models of epileptiform discharge, and presumably in clinical practice. [source] Callosal contribution to ocular dominance in rat primary visual cortexEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 7 2010Chiara Cerri Abstract Ocular dominance (OD) plasticity triggered by monocular eyelid suture is a classic paradigm for studying experience-dependent changes in neural connectivity. Recently, rodents have become the most popular model for studies of OD plasticity. It is therefore important to determine how OD is determined in the rodent primary visual cortex. In particular, cortical cells receive considerable inputs from the contralateral hemisphere via callosal axons, but the role of these connections in controlling eye preference remains controversial. Here we have examined the role of callosal connections in binocularity of the visual cortex in naïve young rats. We recorded cortical responses evoked by stimulation of each eye before and after acute silencing, via stereotaxic tetrodotoxin (TTX) injection, of the lateral geniculate nucleus ipsilateral to the recording site. This protocol allowed us to isolate visual responses transmitted via the corpus callosum. Cortical binocularity was assessed by visual evoked potential (VEP) and single-unit recordings. We found that acute silencing of afferent geniculocortical input produced a very significant reduction in the contralateral-to-ipsilateral (C/I) VEP ratio, and a marked shift towards the ipsilateral eye in the OD distribution of cortical cells. Analysis of absolute strength of each eye indicated a dramatic decrease in contralateral eye responses following TTX, while those of the ipsilateral eye were reduced but maintained a more evident input. We conclude that callosal connections contribute to normal OD mainly by carrying visual input from the ipsilateral eye. These data have important implications for the interpretation of OD plasticity following alterations of visual experience. [source] Endothelial cell-derived bone morphogenetic proteins regulate glial differentiation of cortical progenitorsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 7 2008Tetsuya Imura Abstract Gliogenesis is an important component of cortical development during the postnatal period. Two macroglial cells are generated in a particular order, i.e. astrocytes first and oligodendrocytes later. The mechanisms underlying this sequence of glial differentiation are unknown but interactions with blood vessels are postulated to play a role. We show, using a mouse in-vitro coculture system, that endothelial cells promote astrocyte differentiation but inhibit oligodendrocyte differentiation of postnatal cortical progenitors. Endothelial cells produce bone morphogenetic proteins (BMPs) to activate Sma- and Mad-related protein (Smad) signalling in progenitors and the effects of endothelial cells on glial differentiation are blocked by the BMP antagonist Noggin. Differentiation of progenitors into astrocytes results in the inhibition of endothelial cell growth, accompanied by changes in gene expression of angiogenic factors, indicating bidirectional interactions between progenitors and endothelial cells. In vivo, Smad signalling is activated in various types of cortical cells including progenitors in association with astrogenesis but is inactivated before the peak of oligodendrogenesis. Capillary vessels isolated from the developing cortex express high levels of BMPs. Together, these results demonstrate that endothelial cells regulate glial differentiation by secreting BMPs in vitro and suggest a similar role in cortical gliogenesis in vivo. [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] Cytokeratin profiles of the thymus and thymomas: histogenetic correlations and proposal for a histological classification of thymomasHISTOPATHOLOGY, Issue 5 2000Aims Since cytokeratins (CKs) are useful as differentiation markers for histogenetic and classification studies, we investigated the CK profiles of the thymus and thymomas in an attempt to understand the histogenetic correlation and to propose a histological classification. Methods and results Nine thymuses and 34 thymomas were immunostained for various CKs of different molecular weights and involucrin. Based on cytomorphology and histoarchitecture, thymomas were classified into spindle cell (SC), small polygonal cell (SPC), mixed, organoid, large polygonal cell (LPC) and squamoid (SQ) thymomas for compiling CK profiles. The thymus was shown to comprise four epithelial compartments, each expressing a different CK profile. Different histological types of thymoma expressed different CK profiles. By correlating the CK profiles of the thymus and thymoma, SPC, SC and LPC thymomas appeared to be related to subcapsular, medullary and cortical cells, respectively. Organoid thymoma recapitulated the structure and CK profile of the normal thymus, while SQ thymoma acquired additional squamous type CK. The applicability and usefulness of the proposed histological classification were evaluated on 147 thymomas by correlating the results with their invasive behaviour. One hundred and thirty-nine cases (95%) could be classified and different histological types correlated strongly with their invasive behaviour. Conclusions The thymus is a complex epithelial organ composed of heterogeneous cell types giving rise to various related histological types of thymoma. The results of the CK profile study supports the proposed histological classification, which is pathologically applicable and clinically useful in correlating with invasiveness. This cytomorphological classification, supported by the CK expression patterns, is comparable to Müller-Hermelink classification and the new WHO histological classification except that a separate group of SPC thymoma expressing only CK14 and CK19 was identified and separated from mixed thymoma. [source] Specificity of a new lipid mediator produced by testicular and peritoneal macrophages on steroidogenesisINTERNATIONAL JOURNAL OF ANDROLOGY, Issue 5 2000Lukyanenko Macrophage-derived factor (MDF) is a lipophilic factor produced by rat testicular and peritoneal macrophages that maximally stimulates testosterone production by rat Leydig cells through a steroidogenic acute regulatory protein independent mechanism. The purpose of the present study was to determine whether MDF is also produced by human macrophages, and/or if it acts on human steroidogenic cells. We also studied the tissue-specific functions of MDF by determining if it also acts on steroidogenic cells of the ovary and adrenal glands and, if so, does it require new protein synthesis. It was found that MDF was produced by human peritoneal macrophages, and was capable of stimulating human steroidogenic cells. In terms of tissue specificity, it was found that primary cultures of rat adrenocortical cells respond to MDF with increased secretion of aldosterone and corticosterone, as did rat granulosa cells by producing progesterone. MDF acted in the presence of cycloheximide, indicating that it does not require new protein synthesis. These results indicate that MDF may have significant therapeutic potential and provide a basis for future studies concerning its physiological role in humans. These results further suggest that MDF is not only involved in paracrine regulation of Leydig cells, but also has the potential for the local regulation of steroidogenesis in both granulosa and adrenal cortical cells. [source] The cell membrane complex: Three related but different cellular cohesion components of mammalian hair fibersINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 3 2010C. Robbins J. Cosmet. Sci., 60, 437,465 (July/August 2009) Synopsis The structure, chemistry and physical properties of the cell membrane complex (CMC) of keratin fibers are reviewed, highlighting differences in the three types of CMC. Starting with Rogers' initial description of the CMC in animal hairs, several important developments have occurred that will be described, adding new details to this important structure in mammalian hair fibers. These developments show that essentially all of the covalently bound fatty acids of the beta layers are in the cuticle and exist as monolayers. The beta layers of the cortex are bilayers that are not covalently bonded but are attached by ionic and polar linkages on one side to the cortical cell membranes and on the other side to the delta layer. The delta layer between cortical cells consists of five sublayers; its proteins are clearly different from the delta layer that exists between cuticle cells. The cell membranes of cuticle cells are also markedly different from the cell membranes of cortical cells. Models with supporting evidence are presented for the three different types of cell membrane complex: cuticle,cuticle CMC, cuticle,cortex CMC, and cortex,cortex CMC. [source] Thermal analysis of merino wool fibres without internal lipidsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2007M. Martí Abstract Merino wool is made up of cuticle and cortical cells held together by the cell membrane complex (CMC), which contains a small amount of internal lipids (IWL) (1.5% by mass). IWL have been extracted from wool on account of their considerable dermatological interest owing to their proportion of ceramides. IWL have been extracted by different methods and solvents, methanol and acetone at laboratory and pilot plant levels. Thermal analysis of these extracted wool fibers is presented using thermogravimetry (TG) and differential scanning calorimetry (DSC). TG provides a measurement of the weight loss of the sample as a function of time and temperature. DSC gives information about possible structure modification of extracted wool fibers. Thermoporometry was applied to evaluate the pore size distribution of extracted wool fibers. The results showed that the extraction process increased the pore size distribution and the cumulated pore volume, which is consistent with some changes in the extracted wool CMC. Extracted fiber becomes more hydrophilic and absorbs a large amount of water. We can conclude that the lipid extraction of wool produced no relevant changes in the crystalline fraction when extracted with acetone. However, part of the amorphous keratin material was extracted with methanol, the rest of the crystalline material becoming more stable. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 545,551, 2007 [source] Poster Sessions AP01: Gene Expression and RegulationJOURNAL OF NEUROCHEMISTRY, Issue 2001J. M. Calandria The formation of Cortico-Thalamic projections requires the precise spatial and temporal expression of proteins that are involved in the different stages of synaptogenesis. We reasoned that the underlying molecular mechanism of this process is the differential expression of genes that code for stage specific proteins. Our research objective was to identify the differential expressed mRNAs during the main stages of synapses formation, which starts at embryonic day 12 (E12) and finishes on the first postnatal days in the rat. We approach this problem using Differential Display technique on three distinct ages of rat cerebral cortex that were: E13, E18 and postnatal day 0 (P0). We found 80 differential bands using 54 random primers and 18 of them were cloned and sequenced. The sequence analysis showed among others, a cDNA fragment highly homologous with the human A Kinase Anchoring Protein 450/350 also called CG-NAP. We found that this cDNA fragment homologous to AKAP was up regulated at E15 when cortical cells are undergoing active axogenesis. The expression pattern of this cDNA was confirmed by Real Time PCR. Our findings suggest a possible function for AKAP 450 in the regulation of the state of phosphorylation of centrosomal components during the initial stages of synapses formation during the establishment of Cortico-Thalamic connection. [source] Protective effects of sesamin and sesamolin on hypoxic neuronal and PC12 cellsJOURNAL OF NEUROSCIENCE RESEARCH, Issue 1 2003Rolis Chien-Wei Hou Abstract Reactive oxygen species (ROS) are important mediators of a variety of pathological processes, including inflammation and ischemic injury. The neuroprotective effects of sesame antioxidants, sesamin and sesamolin, against hypoxia or H2O2 -induced cell injury were evaluated by cell viability or lactate dehydrogenase (LDH) activity. Sesamin and sesamolin reduced LDH release of PC12 cells under hypoxia or H2O2 -stress in a dose-dependent manner. Dichlorofluorescein (DCF)-sensitive ROS production was induced in PC12 cells by hypoxia or H2O2 -stress but was diminished in the presence of sesamin and sesamolin. We evaluated further the role of mitogen-activated protein kinases (MAPKs) and caspase-3 in hypoxia-induced PC12 cell death. Extracellular signal-regulated protein kinase (ERK) 1, c-jun N-terminal kinase (JNK), and p38 MAPKs of signaling pathways were activated during hypoxia. We found that the inhibition of MAPKs and caspase-3 by sesamin and sesamolin correlated well with the reduction in LDH release under hypoxia. Furthermore, the hypoxia-induced apoptotic-like cell death in cultured cortical cells as detected by a fluorescent DNA binding dye was reduced significantly by sesamin and sesamolin. Taken together, these results suggest that the protective effect of sesamin and sesamolin on hypoxic neuronal and PC12 cells might be related to suppression of ROS generation and MAPK activation. © 2003 Wiley-Liss, Inc. [source] Direct cell,cell interactions control apoptosis and oligodendrocyte marker expression of neuroepithelial cellsJOURNAL OF NEUROSCIENCE RESEARCH, Issue 3 2001J.P. Hugnot Abstract During brain development, the neuroepithelium generates neurons and glial cells. Proliferation and differentiation of neuroepithelial cells are controlled by a complex combination of secreted factors and more intrinsic or local mechanisms, such as lateral inhibition and asymmetric division. To obtain further insights into the signals governing neuroepithelial cell fate, we used the immortomouse to derive conditionally immortalised cell lines from mouse E10 neuroepithelium. We isolated a nestin-positive basic fibroblast growth factor (bFGF)-responsive cell line (SVE10-23) which mostly differentiate into astrocytes when cocultured with primary cortical cells. We found that, by simply lowering the cell density, SVE10-23 cells embarked on oligodendrocytic differentiation as indicated by the strong expression of galactocerebroside C and 2,3,-cyclic nucleotide 3,-phosphodiesterase. Apoptosis accompanied the differentiation, and all cells died within 1 week. We present here evidence that direct interactions between cells are the main mechanism regulating this oligodendrocytic differentiation. We demonstrate that SVE10-23 cells contact or proximity inhibit their differentiation, prevent apoptosis, and promote their proliferation. Similarly, others nestin-positive precursor cell lines and nonimmortalised bFGF-grown E10 cells were found to spontaneously differentiate at low density, thus generalising the idea that neural precursor fate is regulated by direct cell,cell interactions. The SVE10-23 cell line provides a valuable tool with which to study further the molecular components implicated in this mode of regulation. J. Neurosci. Res. 65:195,207, 2001. © 2001 Wiley-Liss, Inc. [source] ACTH and adrenocortical gap junctionsMICROSCOPY RESEARCH AND TECHNIQUE, Issue 3 2003Sandra A. Murray Abstract Since the initial identification of gap junctions in the adrenal gland, it has been proposed that a system involving direct cell,cell communication might be involved in adrenal cortical functions. Gap junction channels do, in fact, provide pathways for direct intercellular exchange of small molecules (<1,000 Da), many of which have the potential to influence a wide range of cellular activities. Gap junctions are composed of proteins called connexin which, in the adrenal cortex, have proven to be remarkably consistent in both type and zonal distribution with connexin 43 (Cx43) as the predominant component in mammalian adrenal glands thus far evaluated. Only the inner two zones of the cortex (zonae fasciculata and reticularis) exhibit significant amounts of Cx43 and functional coupling. Adrenocorticotropin (ACTH) has been shown to increase Cx43 protein in vivo and in vitro, and a strong correlation has been noted between the presence of gap junctions and certain adrenal cortical functions, especially steroidogenic capacity and cell proliferation. This review summarizes evidence of the Cx43 expression in adrenal cortical cells and the likely role of Cx43 in steroidogenesis and cell proliferation. It is concluded that control of gap junction expression in the adrenal gland is hormonally dependent and is functionally linked to adrenal gland zonation. Microsc. Res. Tech. 61:240,246, 2003. © 2003 Wiley-Liss, Inc. [source] Phymatotrichum (cotton) root rot caused by Phymatotrichopsis omnivora: retrospects and prospectsMOLECULAR PLANT PATHOLOGY, Issue 3 2010SRINIVASA RAO UPPALAPATI SUMMARY Phymatotrichum (cotton or Texas) root rot is caused by the soil-borne fungus Phymatotrichopsis omnivora (Duggar) Hennebert. The broad host range of the fungus includes numerous crop plants, such as alfalfa and cotton. Together with an overview of existing knowledge, this review is aimed at discussing the recent molecular and genomic approaches that have been undertaken to better understand the disease development at the molecular level with the ultimate goal of developing resistant germplasm. Taxonomy:Phymatotrichopsis omnivora (Duggar) Hennebert [synonym Phymatotrichum omnivorum (Shear) Duggar] is an asexual fungus with no known sexual stage. Mitosporic botryoblastospores occasionally form on epigeous spore mats in nature, but perform no known function and do not contribute to the disease cycle. The fungus has been affiliated erroneously with the polypore basidiomycete Sistotrema brinkmannii (Bres.) J. Erikss. Recent phylogenetic studies have placed this fungus in the ascomycete order Pezizales. Host range and disease symptoms: The fungus infects most dicotyledonous field crops, causing significant losses to cotton, alfalfa, grape, fruit and nut trees and ornamental shrubs in the south-western USA, northern Mexico and possibly parts of central Asia. However, this fungus does not cause disease in monocotyledonous plants. Symptoms include an expanding tissue collapse (rot) of infected taproots. In above-ground tissues, the root rot results in vascular discoloration of the stem and rapid wilting of the leaves without abscission, and eventually the death of the plant. Characteristic mycelial strands of the pathogen are typically present on the root's surface, aiding diagnosis. Pathogenicity: Confocal imaging of P. omnivora interactions with Medicago truncatula roots revealed that infecting hyphae do not form any specialized structures for penetration and mainly colonize cortical cells and eventually form a mycelial mantle covering the root's surfaces. Cell wall-degrading enzymes have been implicated in penetration and symptom development. Global gene expression profiling of infected M. truncatula revealed roles for jasmonic acid, ethylene and the flavonoid pathway during disease development. Phymatotrichopsis omnivora apparently evades induced host defences and may suppress the host's phytochemical defences at later stages of infection to favour pathogenesis. Disease control: No consistently effective control measures are known. The long-lived sclerotia and facultative saprotrophism of P. omnivora make crop rotation ineffective. Chemical fumigation methods are not cost-effective for most crops. Interestingly, no genetic resistance has been reported in any of the susceptible crop species. [source] Molecular Reproduction & Development: Volume 77, Issue 6, Cover imageMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 6 2010Article first published online: 21 APR 2010 This adrenal section shown was taken from a 1 year-old mouse lacking Sonic hedgehog (Shh) in the steroidogenic factor-positive adrenal cortical cells during fetal life. Lack of Shh did not affect formation of the cortex (magenta, positive for 3beta-HSD) and medulla (green, positive for tyrosine hydroxylase). However, the mutant adrenal cortex underwent hypoplasia and hypertrophy with age. The section was counterstained with the nuclear dye DAPI (blue). See the accompanying review by Huang and Yao in this issue. [source] Development, dilation and subdivision of cortical layers of gentian (Gentiana asclepiadea) rootNEW PHYTOLOGIST, Issue 1 2003ottníková Summary ,,The structure and development of the cortical layers, especially the endodermis and exodermis, and changes in the cortex caused by the secondary growth of vascular tissues are described in the adventitious roots of gentian (Gentiana asclepiadea). ,,Sections along the whole axis of the soil-grown roots were observed using light microscopy; fluorescence microscopy was used to determine developmental stages of the endodermis and exodermis. ,,Both endodermis and exodermis develop in three stages: Casparian band formation, suberin lamellae deposition and secondary thickening of walls. After the onset of cambial activity (20 mm from apex) cortical cells expand tangentially and subdivision of individual cells starts between 20 mm and 60 mm from apex. Highly differentiated endodermal cells are divided by 0,19 new anticlinal walls, exodermal cells by 0,3 and parenchymatous mid-cortex by 0,1. ,,The additional anticlinal cell walls of the endodermis and exodermis possess neither Casparian bands nor suberin lamellae. Suberin lamellae remain continuous on the surface of extended tangential walls of both layers. There is a correlation between increasing diameter of the secondary vascular tissues and the number of endodermal cells created by subdivision of the original cells. [source] Four new species of Rhodophyceae from Fiji, Polynesia and Vanuatu, South PacificPHYCOLOGICAL RESEARCH, Issue 1 2009Antoine D. R. N'Yeurt SUMMARY Four new species of Rhodophyceae are described from the South Pacific, with type localities in Fiji, French Polynesia and Vanuatu. Chondria bullata from the Tuamotus (French Polynesia), Vanuatu, Palmerston Atoll (Cook Islands) and Fiji is unique owing to its non-constricted axes with markedly protruding, bubble-like cortical cells. Halymenia nukuhivensis, from the Marquesas Islands in French Polynesia, is distinguished from others in the genus by its dichotomous, papery blades issued from a strap-shaped basal region, and the equal proportion of anti-clinal, periclinal and oblique filaments in its medullary layer. Jania articulata, so far known only from the Tuamotus in French Polynesia and Manihiki in the Northern Cook Islands, superficially resembles the genus Amphiroa with its articulated branches with numerous genicula between successive dichotomies, and its large axis diameter. Meristotheca peltata from the Fiji Islands is unique among the genus by its distinctly peltate, erect habit. The recent high number of newly described species from the South Pacific region emphasizes the need for more in-depth surveys, particularly in deeper outer reef slope habitats, which remain for the most part unexplored and could yield particularly interesting new taxa or distributional records. [source] Hydroclathrus (Scytosiphonaceae, Phaeophyceae): Conspectus of the genus and proposal of new species from Australia and HawaiiPHYCOLOGICAL RESEARCH, Issue 4 2003Gerald T. Kraft SUMMARY Representatives of the two current species of Hydroclathrus, Hydroclathrus clathratus (C. Agardh) Howe (the generitype) and Hydroclathrus tenuis Tseng et Lu, are compared to recent collections of the genus from isolated localities in the central and south Pacific: Necker Island and Lord Howe Island, respectively. Although published descriptions of the virtually pan-tropical/warm-temperate H. clathratus portray a species highly variable in the habits and soral distribution patterns of the macro-phases of its life history, our observations support the hypothesis that the newly discovered Pacific island populations represent new species. Hydroclathrus steph-anosorus Kraft, sp. nov., from Lord Howe Island, differs from seemingly typical H. clathratus by the low-domed profiles of its surface cortical cells, aggregates of moniliform hair primordia that are almost always associated with plurangial sori, and particularly by the configurations of the sori themselves, which form discrete, nearly circular rings around the central hair tufts. Hydroclathrus tumulis Kraft et Abbott, sp. nov., from two deep-water localities in the northwestern Hawaiian Islands, has subacutely papillate cortical cells, scattered single, paired or laxly aggregated hair primordia of distinctive obcuneate morphology, and discrete, angular plurangial sori with no predetermined relationship to hairs, the plurangia being relatively laxly aggregated by virtue of their often arising on pedicels formed by the peaked crests of the cortical bearing cells. H. tenuis, although making the most striking visual impression of any of the species because of its exceedingly narrow, fibrous membranes, seems otherwise closest to H. clathratus in cortical cell, hair and soral features, absolute morphological boundaries between the two species being perhaps difficult to draw at times. [source] Apical callus formation and plant regeneration controlled by plant growth regulators on axenic culture of the red alga Gracilariopsis tenuifrons (Gracilariales, Rhodophyta)PHYCOLOGICAL RESEARCH, Issue 3 2000Nair S. Yokoya SUMMARY Axenic cultures of Gracilariopsis tenuifrons (Bird et Oliveira) Fredericq et Hommersand (Gracilariales, Rhodophyta) were established in ASP12-NTA solid medium (0.4% agar and 1.0% sucrose) supplemented with plant growth regulators to evaluate the effects on apical callus formation and plant regeneration. Indole-3-acetic acid (IAA), 2,4-dichlorophenoxyacetic acid (2,4-D) and 6-benzylaminopurine (BA) were added individually or in combinations (IAA : BA) over a range of concentrations from 0.5 to 5 mg L,1. Growth of apical and intercalary segments was stimulated by high concentrations of 2,4-D (5 mg L,1) and a high IAA to BA ratio (IAA : BA = 5:1 mg L,1) respectively. Apical calluses were originated from divisions of apical and cortical cells located at apical regions of thallus segments and lateral branches. Low concentration of IAA (0.5 mg L,1) or a high IAA to BA ratio (IAA : BA = 5:1 mg L,1) were the optimal treatments for inducing apical callus formation in apical segments, while high concentration of IAA (5 mg L,1) stimulated the highest callus induction rate in intercalary segments. Conversely, equal parts IAA and BA (IAA : BA = 1:1 mg L,1) and low concentration of 2,4-D (0.5 mg L,1) stimulated growth of apical calluses from apical and intercalary segments, respectively. Two processes of regeneration were observed: direct regeneration (upright axis originated from cells of proximal region of intercalary segments) and indirect regeneration (adventitious plantlet originated from cells of apical calluses). Direct regeneration was promoted significantly by treatment with a low IAA to BA ratio (IAA : BA= 1:5 mg L,1), and treatments with IAA (0.5 mgL,1) or 2,4-D (0.5 or 5 mg L,1) significantly stimulated the elongation of upright axis. Plant growth regulators are essential to inducing indirect regeneration, and a high concentration of IAA (5 mg L,1) and BA (5 mg L,1) were the optimal treatments for inducing the regeneration of plantlets from apical calluses in apical and intercalary segments, respectively. Regenerating plantlets grew into plants morphologically similar to those formed from germinating spores, and became fertile after 6 weeks. The results suggest that auxins and cytokinins are involved in developmental regulatory processes in G. tenuifrons. The regeneration process from calluses in species of Gracilariales was observed for the first time in the present study. The culture system described for G. tenuifrons could be useful for micropropagation and for biotechnological applications in agarophytic algae. [source] Isolation and characterization of cgchi3, a nodule-specific gene from Casuarina glauca encoding a class III chitinasePHYSIOLOGIA PLANTARUM, Issue 3 2007Ana Fortunato Chitinases (EC 3.2.1.14) catalyse the hydrolysis of chitin, a homopolymer of ,-1,4-linked N -acetyl- d -glucosamine residues. Plant chitinases are involved in a wide variety of processes; in particular, their expression has been found to be enhanced in symbiotic and pathogenic plant,microbe interactions. During this work we have cloned and characterized a gene encoding a class III chitinase from actinorhizal nodules of Casuarina glauca (cgchi3). CGCHI3 was found to be encoded by a single gene that was specifically activated in nodules as compared with uninoculated control roots and leaves. The expression of this gene was further enhanced in nodules after salicylic acid treatment and completely repressed after wounding. In situ hybridisation analysis revealed that cgchi3 is an early nodulin gene, being expressed in the meristem and in the uninfected cortical cells of young nodules. Based on the obtained results we suggest that this gene is involved in nodule development. This is the first report on a class III chitinase coding gene that is specifically activated during actinorhizal symbiosis. [source] Pyrimidine nucleotide and nucleic acid synthesis in embryos and megagametophytes of white spruce (Picea glauca) during germinationPHYSIOLOGIA PLANTARUM, Issue 1 2002Claudio Stasolla Pyrimidine nucleotide synthesis was investigated in isolated germinating zygotic embryos and separated megagametophytes of white spruce by following the metabolic fate of 14C-labelled orotic acid, uridine, and uracil, as well as by measuring the activities of the major enzymes participating in nucleotide synthesis. The rate of nucleic acid synthesis in these tissues was also examined by tracer experiments and autoradiographic studies conducted with labelled thymidine, and by conventional light microscopy. From our results, it emerges that changes in the contribution of the de novo and salvage pathways of pyrimidines play an important role during the initial stages of zygotic embryo germination. Preferential utilization of uridine for nucleic acid synthesis, via the salvage pathway, was observed at the onset of germination, before the restoration of a fully functional de novo pathway. Similar metabolic changes, not observed in the gametophytic tissue, were also documented in somatic embryos previously. These alterations of the overall pyrimidine metabolism may represent a strategy for ensuring the germinating embryos with a large nucleotide pool. Utilization of 14C-thymidine for nucleic acid synthesis increased in both dissected embryos and megagametophytes during germination. Autoradiographic and light microscopic studies indicated that soon after imbibition, DNA synthesis was preferentially initiated along the embryonic axis, especially in the cortical cells. Apical meristem reactivation was a later event, and the root meristem became activated before the shoot meristem. Taken together, these results indicate that precise changes in nucleotide and nucleic acid metabolism occur during the early phases of embryo germination. [source] Protective effects of 3,-deoxy-4-O-methylepisappanol from Caesalpinia sappan against glutamate-induced neurotoxicity in primary cultured rat cortical cellsPHYTOTHERAPY RESEARCH, Issue 3 2010Hyung-In Moon Abstract To examine the neuroprotective effects of Caesalpinia sappan L., we tested its protection against the glutamate-induced neurotoxicity in primary cortical cultured neurons. We found that an aqueous extract of this medicinal plant exhibited significant protection against glutamate-induced toxicity in primary cultured rat cortical cells. In order to clarify the neuroprotective mechanism(s) of this observed effect, isolation was performed to seek and identify active fractions and components. By such fractionation, two known compounds , sappanchalcone and 3,-deoxy-4-O-methylepisappanol , were isolated from the methanol extracts from the air-dried and chipped C. sappan. Among these two compounds, 3,-deoxy-4-O-methylepisappanol exhibited significant neuroprotective activities against glutamate-induced toxicity, exhibiting cell viability of about 50%, at concentrations ranging from 0.1,,M to 10,,M. Therefore, the neuroprotective effect of C. sappan might be due to the inhibition of glutamate-induced toxicity by the protosappanin derivative it contains. Copyright © 2009 John Wiley & Sons, Ltd. [source] Neuroprotective effect of luteolin on amyloid , protein (25,35)-induced toxicity in cultured rat cortical neuronsPHYTOTHERAPY RESEARCH, Issue S1 2010Hao-Yuan Cheng Abstract The present study was carried out to investigate the neuroprotective effect of luteolin on amyloid , (A,) (25,35)-induced neurotoxicity using cultured rat cortical neurons. After exposure of primary cultures of rat cortical cells to 10 ,M A, (25,35) for 48 h, cortical cell cultures exhibited marked apoptotic death. Pretreatment with luteolin (1, 10 ,M) significantly protected cortical cell cultures against A, (25,35)-induced toxicity. Luteolin (1, 10 ,M) showed a concentration-dependent inhibition on 10 ,M A, (25,35)-induced apoptotic neuronal death, as assessed by MTT assay. Furthermore, luteolin reduced apoptotic characteristics by DAPI staining. For Western blot analysis, the results showed that the protective effect of luteolin on A, (25,35)-induced neurotoxicity was mediated by preventing of ERK-p, JNK, JNK-p, P38-p and caspase 3 activations in rat primary cortical cultures. Taken together, the results suggest that luteolin prevents A, (25,35)-induced apoptotic neuronal death through inhibiting the protein level of JNK, ERK and p38 MAP kinases and caspase 3 activations. Copyright © 2009 John Wiley & Sons, Ltd. [source] ESP-102, a combined extract of Angelica gigas, Saururus chinensis and Schizandra chinensis, protects against glutamate-induced toxicity in primary cultures of rat cortical cellsPHYTOTHERAPY RESEARCH, Issue 11 2009Choong Je Ma Abstract It was reported previously that ESP-102, a combined extract of Angelica gigas, Saururus chinensis and Schizandra chinensis, significantly improved scopolamine-induced memory impairment in mice and protected primary cultured rat cortical cells against glutamate-induced toxicity. To corroborate this effect, the action patterns of ESP-102 were elucidated using the same in vitro system. ESP-102 decreased the cellular calcium concentration increased by glutamate, and inhibited the subsequent overproduction of cellular nitric oxide and reactive oxygen species to the level of control cells. It also preserved cellular activities of antioxidative enzymes such as superoxide dismutase, glutathione peroxidase and glutathione reductase reduced in the glutamate-injured neuronal cells. While a loss of mitochondrial membrane potential was observed in glutamate treated cells, the mitochondrial membrane potential was maintained by ESP-102. These results support that the actual mechanism of neuroprotective activity of ESP-102 against glutamate-induced oxidative stress might be its antioxidative activity. Copyright © 2009 John Wiley & Sons, Ltd. [source] Oxidative gating of water channels (aquaporins) in corn rootsPLANT CELL & ENVIRONMENT, Issue 4 2006QING YE ABSTRACT An oxidative gating of water channels (aquaporins: AQPs) was observed in roots of corn seedlings as already found for the green alga Chara corallina. In the presence of 35 m m hydrogen peroxide (H2O2) , a precursor of hydroxyl radicals (*OH) , half times of water flow (as measured with the aid of pressure probes) increased at the level of both entire roots and individual cortical cells by factors of three and nine, respectively. This indicated decreases in the hydrostatic hydraulic conductivity of roots (Lphr) and of cells (Lph) by the same factors. Unlike other stresses, the plant hormone abscisic acid (ABA) had no ameliorative effect either on root Lphr or on cell Lph when AQPs were inhibited by oxidative stress. Closure of AQPs reduced the permeability of acetone by factors of two in roots and 1.5 in cells. This indicated that AQPs were not ideally selective for water but allowed the passage of the organic solute acetone. In the presence of H2O2, channel closure caused anomalous (negative) osmosis at both the root and the cell level. This was interpreted by the fact that in the case of the rapidly permeating solute acetone, channel closure caused the solute to move faster than the water and the reflection coefficient (,s) reversed its sign. When H2O2 was removed from the medium, the effects were reversible, again at both the root and the cell level. The results provide evidence of oxidative gating of AQPs, which leads on to inhibition of water uptake by the roots. Possible mechanisms of the oxidative gating of AQPs induced by H2O2 (*OH) are discussed. [source] Extracellular complexation of Cd in the Hartig net and cytosolic Zn sequestration in the fungal mantle of Picea abies , Hebeloma crustuliniforme ectomycorrhizasPLANT CELL & ENVIRONMENT, Issue 11 2000B. Frey ABSTRACT Compartmentation of heavy metals on or within mycorrhizal fungi may serve as a protective function for the roots of forest trees growing in soils containing elevated concentrations of metals such as Cd and Zn. In this paper we present the first quantitative measurements by X-ray microanalysis of heavy metals in high-pressure frozen and cryosectioned ectomycorrhizal fungal hyphae. We used this technique to analyse the main sites of Cd and Zn in fungal cells of mantle and Hartig net hyphae and in cortical root cells of symbiotic Picea abies , Hebeloma crustuliniforme associations to gain new insights into the mechanisms of detoxification of these two metals in Norway spruce seedlings. The mycorrhizal seedlings were exposed in growth pouches to either 1 mM Cd or 2 mM Zn for 5 weeks. The microanalytical data revealed that two distinct Cd- and Zn-binding mechanisms are involved in cellular compartmentation of Cd and Zn in the mycobiont. Whereas extracellular complexation of Cd occurred predominantly in the Hartig net hyphae, both extracellular complexation and cytosolic sequestration of Zn occurred in the fungal tissue. The vacuoles were presumed not to be a significant pool for Cd and Zn storage. Cadmium was almost exclusively localized in the cell walls of the Hartig net (up to 161 mmol kg,1 DW) compared with significantly lower concentrations in the cell walls of mantle hyphae (22 mmol kg,1 DW) and in the cell walls of cortical cells (15 mmol kg,1 DW). This suggests that the apoplast of the Hartig net is a primary accumulation site for Cd. Zinc accumulated mainly in the cell walls of the mantle hyphae (111 mmol kg,1 DW), the Hartig net hyphae (130 mmol kg,1 DW) and the cortical cells (152 mmol kg,1 DW). In addition, Zn occurred in high concentrations in the cytoplasm of the fungal mantle hyphae (up to 164 mmol kg,1 DW) suggesting that both the cell walls and the cytoplasm of fungal tissue are the main accumulation sites for Zn in P. abies resulting in decreased Zn transfer from the fungus to the root. [source] Histological Structure of the Adrenal Gland of the Bottlenose Dolphin (Tursiops truncatus) and the Striped Dolphin (Stenella coeruleoalba) from the Adriatic SeaANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 1 2010S. Vukovi Summary The structure of the adrenal gland was studied in 11 bottlenose dolphins (Tursiops truncatus), and five striped dolphins (Stenella coeruleoalba). These species are legally protected in Croatia. All examined animals died of natural causes and were found stranded along eastern Adriatic coast. In both species the adrenal gland consists of a cortex and a medulla; the cortex is divided into three zones. Whereas in the bottlenose dolphin, there is a zona arcuata which contains columnar cells arranged in the form of arches; in the striped dolphin this zone is replaced by zona glomerulosa containing rounded clusters of polygonal cells. In both species, the zona fasciculata consists of radially oriented cords of polygonal cells, whereas in zona reticularis cells are arranged in branching and anastomosing cords. The adrenal medulla in both species contains dark, epinephrine-secreting cells and light norepinephrine-secreting cells. Epinephrine-secreting cells are localized in the outer part of the medulla, whereas norepinephrine-secreting cells are found in the inner part, arranged in clusters and surrounded by septa of thin connective tissue. The gland is surrounded by a thick connective-tissue capsule, from where thick trabeculae extend towards the interior. In the bottlenose dolphin, group of cells resembling both medullar and cortical cells can be seen within the capsule; whereas only groups of cells resembling cortical cells are found within the capsule of the striped dolphin. In the bottlenose dolphin invagination of the adrenal cortex into the medulla is obvious as well as medullary protrusions extending through cortex to the connective tissue capsule. [source] On the Structure of the Adrenal Gland of the Common Seal (Phoca vitulina vitulina)ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 5 2004H. Bragulla Summary The adrenal gland is a vitally important endocrine gland that occupies a central role in the regulatory mechanisms of the body metabolism. Environmental stress factors lead to permanent strain and overload of the body resulting in structural alterations of the adrenals that in turn are followed by hormonal imbalances. This leads to an increased susceptibility to bacterial and viral diseases. The recurrence of numerous fatalities in the different seal populations of the North Sea (during the years 1988, 1989 and 2002), of the Baikal Lake and Caspian Sea (during the years 2000 and 2001) were the motive for a morphological investigation of the species-specific structure of the adrenal gland of the common seal in order to differentiate environmental stress-induced pathological alterations from the physiological structure of this organ. The study was based on adrenals of 112 common seals (Phoca vitulina vitulina) using light microscopic and transmission and scanning electron microscopic methods. The phocine adrenal gland displays several structural characteristics. Originating from the connective tissue organ capsule, narrow and broad septa intersperse the adrenal cortex. These septa contain blastemata as a reserve for the regeneration of hormone-producing cortical cells. Such blastemata are also occurring in the form of an intermediate zone in between the zona glomerulosa and zona fasciculata in the phocine adrenal cortex. Another species-specific characteristic is an inverse part of the adrenal cortex encircling the central vein of the organ. These structural features have to be considered in assessment and definition of pathological alterations of the adrenals as observed in the form of exhausted blastema cell pools in the adrenocortex of seals perished in the mentioned phocine mass mortalities. [source] Aberrantly differentiated cells in benign pilomatrixoma reflect the normal hair follicle: immunohistochemical analysis of Ca2+ -binding S100A2, S100A3 and S100A6 proteinsBRITISH JOURNAL OF DERMATOLOGY, Issue 2 2005K. Kizawa Summary Background, Pilomatrixoma is a common benign cutaneous tumour containing differentiated hair matrix cells. This tumour is mainly composed of basophilic, transitional, shadow and squamoid cells. Although some S100 proteins are expressed in a tissue-specific manner in the hair follicle (e.g. S100A2 in the outer root sheath, S100A3 in the cortex and cuticle, and S100A6 in the inner root sheath), little information is available concerning their distribution in the aberrantly differentiated tissues of pilomatrixoma. Objectives, To characterize the disordered epithelial elements of pilomatrixoma by localizing S100A2, S100A3 and S100A6 proteins. Methods, Immunohistochemistry and dual-immunofluorescence microscopy were performed on 22 pilomatrixoma specimens using antibodies specific to the three proteins. Results, Tissue-specific distribution of the S100 proteins investigated was preserved in the morphologically disordered tumour tissues. Anti-S100A2 antibody stained squamoid cells and putative outer root sheath cells; basophilic and potential hair matrix cells were occasionally stained. S100A3 staining was found in transitional cells and putative cortical cells, and was strong in both dispersed cells and hair-like structures surrounding cells which were presumably cuticular cells. Anti-S100A6 antibody labelled some S100A3-negative transitional cell strands, potentially inner root sheath cells. Conclusions, The epithelial elements of pilomatrixoma can be characterized using S100 proteins as biochemical markers. Our results show that pilomatrixomas retain a certain degree of differentiation indicative of distinct hair-forming cells. [source] Pinusolide and 15-methoxypinusolidic acid attenuate the neurotoxic effect of staurosporine in primary cultures of rat cortical cellsBRITISH JOURNAL OF PHARMACOLOGY, Issue 1 2007K A Koo Background and purpose: Apoptosis is a fundamental process required for neuronal development but also occurs in most of the common neurodegenerative disorders. In an attempt to obtain an anti-apoptotic neuroprotective compound from natural products, we isolated the diterpenoids, pinusolide and 15-MPA, from B. orientalis and investigated their neuroprotective activity against staurosporine (STS) -induced neuronal apoptosis. In addition, we determined the anti-apoptotic mechanism of these compounds in rat cortical cells. Experimental approach: Primary cultures of rat cortical cells injured by STS were used as an in vitro assay system. Cells were pretreated with pinusolide or 15-MPA before exposure to STS. Anti-apoptotic activities were evaluated by the measurement of cytoplasmic condensation and nuclear fragmentation. The levels of cellular peroxide, malondialdehyde (MDA) and [Ca2+]i, as well as the activities of superoxide dismutase (SOD) and caspase-3/7, were measured. Key results: Pinusolide and 15-MPA, at a concentration of 5.0 ìM, reduced the condensed nuclei and rise in [Ca2+]i that accompanies apoptosis induced by 100 nM STS. Pinusolide and 15-MPA also protected the cellular activity of SOD, an antioxidative enzyme reduced by STS insult. Furthermore, the overproduction of reactive oxygen species and lipid peroxidation induced by STS was significantly reduced in pinusolide and 15-MPA treated cells. In addition, pinusolide and 15-MPA inhibited STS-induced caspase-3/7 activation. Conclusions and Implications: These results show that pinusolide and 15-MPA protect neuronal cells from STS-induced apoptosis, probably by preventing the increase in [Ca2+]i and cellular oxidation caused by STS, and indicate that they could be used to treat neurodegenerative diseases. British Journal of Pharmacology (2007) 150, 65,71. doi:10.1038/sj.bjp.0706944 [source] | |||||||||||||||||||||||||