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Ultrathin Sections (ultrathin + section)
Selected AbstractsThe Occurrence of Phytoplasmas in Apple Trees Showing Branch TwistingJOURNAL OF PHYTOPATHOLOGY, Issue 7-8 2005J. Fránová Abstract Apple trees showing malformation of branches were found at different locations in the Czech Republic. Ultrathin sections of tissues from diseased trees showed the presence of pleomorphic bodies resembling phytoplasma. Nested-polymerase chain reaction (PCR) assays with primers amplifying16S,23S ribosomal RNA (rRNA) sequences specific for phytoplasma and the subsequent restriction fragment length polymorphism (RFLP) analyses allowed to classify the detected phytoplasmas in the aster yellows group, subgroup 16SrI-C in 12 trees, single (11 plants) or mixed with phytoplasma belonging to subgroup 16SrI-B (1 plant). Phytoplasma of apple proliferation group (16SrX-A subgroup) were identified in cv. Mat,ino. Apple tree cv. P,e,tické r,,ové was infected by phytoplasma of the 16SrX-A and 16SrI-B subgroups. No phytoplasmas were detected in asymptomatic apple trees. [source] Myelin thickenings in val 102/fs null mutation of MPZ geneJOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 2 2004MV De Angelis Myelin thickenings, abnormal myelin foldings and tomacula have been rarely described in CMT1B. In two unrelated patients of different age (patient 1: 29 years old; patient 2: 65 years old) with CMT1B and Val 102/fs null mutation of MPZ gene we performed morphometric analysis, teased fibers and ultrastructural examination of sural nerve. We found: 1) markedly decreased fiber density with prevalent loss of large diameter fibers (patient 1: 4419 fibers/mm2; patient 2: 1326 fibers/mm2); 2) evidence of de-remyelination; and 3) paranodal and internodal myelin thickenings in virtually all fibers. Patient 1 has myelin thickenings measuring more than 50% of the fiber diameter in 14% of fibers and thickenings greater than 30% in 33% of fibers. Patients 2 presents myelin thickenings measuring more than 50% of fiber diameter in 23% of fibers and thickening greater than 30% in 49% of fibers. When considering the absolute measure of myelin thickenings and their number over 100 internodes, patient 1 presents 150 small myelin thickenings (<8 mm of diameter) whereas patient 2 has 57. The number of globules (8,12 mm of diameter) is 56 in patient 1 and 45 in patient 2. The number of myelin thickenings greater than 12 mm is 33 in patient 1 and 45 in patient 2. Ultrathin sections showed myelin infoldings, outfoldings and uncompacted myelin. CMT1B with a heterozygous null mutation of MPZ gene is characterized by abundant focal myelin thickenings. Similar findings have been described in the P0 deficient heterozygous mice. [source] Characterization of the Surface Properties of Commercially Available Dental Implants Using Scanning Electron Microscopy, Focused Ion Beam, and High-Resolution Transmission Electron MicroscopyCLINICAL IMPLANT DENTISTRY AND RELATED RESEARCH, Issue 1 2008Tobias Jarmar PhD ABSTRACT Background:, Since osseointegration of the respective implant is claimed by all manufacturing companies, it is obvious that not just one specific surface profile including the chemistry controls bone apposition. Purpose:, The purpose was to identify and separate out a particular set of surface features of the implant surfaces that can contribute as factors in the osseointegration process. Material and Methods:, The surface properties of several commercially available dental implants were extensively studied using profilometry, scanning electron microscopy, and transmission electron microscopy. Ultrathin sections prepared with focused ion beam microscopy (FIB) provided microstructural and chemical data which have not previously been communicated. The implants were the Nobel Biocare TiUnite® (Nobel Biocare AB, Göteborg, Sweden), Nobel Biocare Steri-Oss HA-coated (Nobel Biocare AB, Yorba Linda, CA, USA), Astra-Tech OsseoSpeedÔ (Astra Tech AB, Mölndal, Sweden), Straumann SLA® (Straumann AG, Waldenburg, Switzerland), and the Brĺnemark Integration Original Fixture implant (Brĺnemark Integration, Göteborg, Sweden). Results:, It was found that their surface properties had differences. The surfaces were covered with crystalline TiO2 (both anatase and rutile), amorphous titanium oxide, phosphorus doped amorphous titanium oxide, fluorine, titanium hydride, and hydroxyapatite, respectively. Conclusion:, This indicates that the provision of osseointegration is not exclusively linked to a particular set of surface features if the implant surface character is a major factor in that process. The studied methodology provides an effective tool to also analyze the interface between implant and surrounding bone. This would be a natural next step in understanding the ultrastructure of the interface between bone and implants. [source] Ultrastructural and electron energy-loss spectroscopic analysis of an extracellular filamentous matrix of an environmental bacterial isolateENVIRONMENTAL MICROBIOLOGY, Issue 9 2007Uta Böckelmann Summary Strain F8, a bacterial isolate from ,river snow', was found to produce extracellular fibres in the form of a filamentous network. These extracellular filaments, which were previously shown to be composed of DNA, have been studied for the first time by ultrastructural and electron energy-loss spectroscopy in the present work. ,Whole mount' preparations of strain F8 indicate these polymers are ultrastructurally homogeneous and form a network of elemental filaments, which have a width of 1.8,2.0 nm. When incubated at pH 3.5 with colloidal cationic ThO2 tracers they become intensely stained (electron dense), affording direct evidence that the fibres are negatively charged and thus acidic chemically. Elemental analysis of the extracellular filaments by Energy-filtered Transmission Electron Microscopy revealed phosphorus to be the main element present and, because pretreatment of F8 cells with DNase prevented thorium labelling, the fibres must be composed of extracellular DNA (eDNA). Neither ultrathin sections nor ,whole mount negative stain' caused DNA release by general cell lysis. Additionally, cells infected with phages were never observed in ultrathin sections and phage particles were never detected in whole mount samples, which rules out the possibility of phages being directly involved in eDNA release. [source] Convergence of excitatory and inhibitory inputs onto CCK-containing basket cells in the CA1 area of the rat hippocampusEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2004Ferenc Mátyás Abstract The number and distribution of excitatory and inhibitory inputs affect the integrative properties of neurons. These parameters have been studied recently for several hippocampal neuron populations. Besides parvalbumin- (PV) containing cells that include basket and axo-axonic cells, cholecystokinin (CCK)-containing interneurons also form a basket cell population with several properties distinct from PV cells. Here, at the light microscopic level, we reconstructed the entire dendritic tree of CCK-immunoreactive (IR) basket cells to describe their geometry, the total length and laminar distribution of their dendrites. This was followed by an electron microscopic analysis of serial ultrathin sections immunostained against ,-aminobutyric acid, to estimate the density of excitatory and inhibitory synapses on their somata, axon initial segments and different subclasses of dendrites. The dendritic tree of CCK-IR basket cells has an average length of 6300 µm and penetrates all layers. At the electron microscopic level, CCK basket cells receive dendritic inputs with a density of 80,230 per 100 µm. The ratio of inhibitory inputs is relatively high (35%) and increases towards the soma (83%). The total numbers of excitatory and inhibitory synapses converging onto CCK-IR cells are ,,8200. Comparison of the two, neurochemically distinct basket cells reveals that CCK-containing basket cells receive much less synaptic input than PV cells; however, the relative weight of inhibition is higher on CCK cells. Additional differences in their anatomical and physiological properties predict that CCK basket cells are under a more diverse, elaborate control than PV basket cells, and thus the function of the two populations must be different. [source] Inter-crystallite nanoretention of self-etching adhesives at enamel imaged by transmission electron microscopyEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 6 2002Matthias Hannig The purpose of this in vitro study was to analyse the mode of action of self-etching adhesive systems when applied for resin-to-enamel bonding. Transmission electron microscopy was used to investigate the enamel,resin interface after application of non-rinsing self-etching adhesive systems based on phosphoric acid estered methacrylates (Clearfil Liner Bond 2, Clearfil SE Bond, Etch & Prime 3.0 and Resulcin AquaPrime) compared with conventional phosphoric acid etching and bonding (Heliobond). Non-decalcified ultrathin sections from the interface between enamel and self-etching adhesive systems revealed a 1.5,3.2-µm deep enamel surface layer characterized by a less-dense arrangement of enamel crystallites separated from each other by nanometer-sized spaces. A 1.5,3.2-µm wide, netlike resinous structure was observed in corresponding decalcified specimens, indicating that self-etching priming agents dissolve the peripheral and central part of the enamel crystallites, while simultaneously promoting inter- and intra-crystallite monomer infiltration. A similar pattern, but greater depth (6.9 µm) of enamel surface hybridization was found in the phosphoric acid-etched and bonded specimens. The nanoretentive interlocking between enamel crystallites and resin could explain the potential of self-etching adhesive systems in resin-to-enamel bonding despite the less distinct enamel etching pattern observed in scanning electron microscopy investigations. [source] Ultrastructural preservation of rat embryonic dental tissues after rapid fixation and dehydration under microwave irradiationEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 1 2000Luciana F. Massa Adequate preservation of the cells and matrix of mineralising tissues remains difficult, as organic components and initial mineral deposits may be lost during conventional processing for electron microscopy. In this study, we have reduced significantly the processing time using microwave irradiation. Rat molar tooth germs were fixed in 4% glutaraldehyde+4% formaldehyde with 0.1 M sodium cacodylate in a laboratory microwave oven for two periods of 20 s with a maximal temperature of 37°C. After conventional washing and post-fixation, specimens were dehydrated in graded ethanols under microwave irradiation for a total of 7 min 20 s. For comparison, some specimens were processed by conventional methods. After embedding, ultrathin sections were examined by electron microscopy. In differentiating ameloblasts and odontoblasts, plasma membranes, mitochondria, rough endoplasmic reticulum, the Golgi complex, together with all other cytoplasmic organelles exhibited excellent preservation. Microtubules, microfilaments and coated vesicles were particularly evident. Crystal-like mineral deposits were conspicuously present in relation to dentine matrix vesicles and collagen fibrils as well as in enamel matrix. The matrix of forming enamel had a globular electron-lucent appearance. It is concluded that this is a rapid method which provides a preserved or even improved morphology. [source] Expression of chemosensory proteins in hairs on wings of Locusta migratoria (Orthoptera: Acrididae)JOURNAL OF APPLIED ENTOMOLOGY, Issue 6 2008S.-H. Zhou Abstract The hairs on the wings of Locusta migratoria were observed and mapped using light microscopy, as well as by scanning and transmission electron microscopy. Based on their ultrastructure, we can distinguish four main types of hairs on the wings of adult L. migratoria, viz, short, medium and long hairs, and sensilla chaetica. The long hairs are located only on the ventral surface of the hindwing, whereas the other three types are present both on the dorsal and ventral surfaces of forewing and hindwing in both sexes. Medium hairs and sensilla chaetica are significantly more abundant on the dorsal surface of forewings in both females and males, than on the ventral surface, whereas the opposite was observed for short hairs (P < 0.01). No significant difference between males and females was observed in the density of any type of hairs (P > 0.1). Several dendritic branches, enveloped by a dendrite sheath, are situated in the lymph cavity of sensilla chaetica. Instead, no dendritic structure was observed in the cavity of the other three types of hairs. Immunocytochemical localization of chemosensory proteins (CSPs) was performed on ultrathin sections of hairs on wings. The antiserum against chemosensory proteins from L. migratoria (LmigCSP-II) strongly labelled sensilla chaetica, with gold granules only found in the outer sensillum lymph. In addition, the epidermal cell membrane of the wing was stained by the antiserum against LmigCSP-II. The other three types of hairs were never labelled. The results indicate that the wings might involve in contact chemoreception process. [source] Rapid contrasting of ultrathin sections using microwave irradiation with heat dissipationJOURNAL OF MICROSCOPY, Issue 2 2001F. Hernández-Chavarría The use of microwave irradiation (MWI) to accelerate fixation, dehydration and contrasting (staining) for electron microscopy has been applied to the development of rapid methods to process biological samples in electron microscopy. A simple explanation is that the reduced time in those procedures is due to heating. In this paper we propose a contrasting method for thin sections that avoids the thermal effects of MWI. Grids with thin sections of mouse kidney, the dinoflagellate Alexandrium monilatum, spermatophores of the fly Archicepsis diversiformis, the bacteria Acinetobacter calcoaceticum and Enterobacter cloacae were placed into Beem capsules and stained with uranyl acetate and lead citrate, while immersed in an ice-water bath, and irradiated for periods ranging from 30 s to 2 min. After each contrasting procedure, the Beem capsule was filled with distilled water to wash the grids under MWI with the same irradiation time as used to contrast. Good results were obtained on irradiating for 1 min and the temperature of the Beem capsule was maintained around 5 °C. [source] Ultrastructure of the protonephridial system in Neodasys chaetonotoideus (Gastrotricha: Chaetonotida) and in the ground pattern of Gastrotricha,JOURNAL OF MORPHOLOGY, Issue 7 2007Alexander Kieneke Abstract The taxon Neodasys has a basal position within Gastrotricha. This makes it very interesting for phylogenetic considerations in this group. To complete the reconstruction of the nephridial system in the stem species of Gastrotricha started earlier, we have studied the whole protonephridial system of Neodasys chaetonotoideus by means of complete sets of ultrathin sections and TEM. In many characters, protonephridia of N. chaetonotoideus resemble those of macrodasyidan gastrotrich species. For example, each of the six protonephridia, arranged in three pairs, consists of three distinct cells that constitute the continuous protonephridial lumen. Especially, the terminal cell of the protonephridia of N. chaetonotoideus shows a striking pattern: The perforation of the filter region is a meandering cleft that is continuous with the seam of the enfolded lumen of that cell. With the results presented here and that of former TEM studies, we give a comprehensive idea of the excretory organs in the ground pattern of Gastrotricha. Moreover, we can elaborate on the hypothesized protonephridial system in the stem species of Bilateria. We suggest that a meandering filtration cleft is a feature of the ground pattern of the Bilateria. J. Morphol., 2007. © 2007 Wiley-Liss, Inc. [source] Immunolocalization of 1,3-,-Glucanases Secreted by Gaeumannomyces graminis var. tritici in Infected Wheat RootsJOURNAL OF PHYTOPATHOLOGY, Issue 5 2010Yongting Yu Abstract The distribution of extracellular 1,3-,-glucanase secreted by Gaeumannomyces graminis var. tritici (Ggt) was investigated in situ in inoculated wheat roots by immunogold labelling and transmission electron microscopy. Antiserum was prepared by subcutaneously injecting rabbits with purified 1,3-,-glucanase secreted by the pathogenic fungus. A specific antibody of 1,3-,-glucanase, anti-GluGgt, was purified and characterized. Double immunodiffusion tests revealed that the antiserum was specific for 1,3-,-glucanase of Ggt, but not for 1,3-,-glucanase from wheat plants. Native polyacrylamide gel electrophoresis of the purified and crude enzyme extract and immunoblotting showed that the antibody was monospecific for 1,3-,-glucanase in fungal extracellular protein populations. After incubation of ultrathin sections of pathogen-infected wheat roots with anti-1,3-,-glucanase antibody and the secondary antibody, deposition of gold particles occurred over hyphal cells and the host tissue. Hyphal cell walls and septa as well as membranous structures showed regular labelling with gold particles, while few gold particles were detected over the cytoplasm and other organelles such as mitochondria and vacuoles. In host tissues, cell walls in contact with the hyphae usually exhibited a few gold particles, whereas host cytoplasm and cell walls distant from the hyphae were free of labelling. Furthermore, over lignitubers in the infected host cells labelling with gold particles was detected. No gold particles were found over sections of non-inoculated wheat roots. The results indicate that 1,3-,-glucanase secreted by Ggt may be involved in pathogenesis of the take-all fungus through degradation of callose in postinfectionally formed cell wall appositions, such as lignitubers. [source] Ultrastructure of the vegetative gametophytic cells of Porphyra leucosticta (Rhodophyta) grown in red, blue and green lightPHYCOLOGICAL RESEARCH, Issue 4 2002Ioannes Tsekos SUMMARY The ultrastructure of the vegetative gametophytic cells of Porphyra leucosticta Thuret grown in red, blue and green light was studied both in ultrathin sections and in replicas of rapidly frozen cells. High activity of dictyosornes and mucilage sacs results in a dramatic decrease of the protoplasmic area and in thicker cell walls in red light in comparison with blue light and the control. There are numerous well-formed phycobili-somes in blue light, whereas not well-formed ones are present in red and especially in green light. There are also many phycobilisomes in the intrapyrenoidal thylakoids in blue light, fewer in green light, but they are absent in red light and in the control. It seems that in red and especially in green light, the phycobilisomes have fewer rods than in blue light. In green light, chloroplasts bear numerous genophores in contrast to blue and red light. The spacings of neighboring parallel thylakoids are as follows: control 64.3 nm, blue light 90.6 nm, red light 41.3 nm, green light 43.7 nm. Due to the relatively small spacing of the neighboring parallel thylakoids in red (41.3 nm) and in green light (43.7 nm) and of the given height of phycobilisomes (35 nm), the alternate phycobilisomes attached to neighboring lamellae are forced to interdigitate. The density of phycobilisomes per square micrometer of thylakoid surface dramatically increases in blue light (800 ,m,2) in relation to red (250 ,m,2) and green light (180 ,m,2). The protoplasmic fracture face of the thylakoids reveals numerous, tightly packed, but randomly distributed particles. The particle size distribution is uniform in the two types of fracture faces, with an average diameter of about 11.5 nm. In blue light, both the phycobilisomes and exoplasmic face particles are organized into rows with a spacing of 60,70 nm. The results (changes: in the protoplasmic area; in the spacing of the thylakoids; in phycobilisome arrangement; in structure, shape and size of phycobilisomes; and in the accumulation of plastoglobuli), have shown that the monochromatic light (blue, red and green) brings about marked changes in the package effect and consequently in the efficiency of light absorption. In addition, the blue light contributes to the intense production of chlorophyll a, phycoerythrin, phycocyanin and soluble proteins, while intense production of polysaccharidic material is attributed to red light. [source] Intercellular Junctions in Rabbit Eye Ora SerrataANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 5 2006L. Nobeschi Summary The aim of this study was to describe and localize the intercellular junctions in the ora serrata region of albino and pigmented rabbit eyes. Eyes of albino and pigmented rabbits were fixed and processed for transmission electron microscopy. Light and electron microscope examination was carried out on semithin and ultrathin sections. The ora serrata region showed adherens, gap and tight junctions in the retinal and ciliary margins of albino and pigmented rabbit eyes. In the retinal margin, zonulae adherens between Müller cells and photoreceptors are associated with tight junctions. In the ciliary margin, epithelial cells are joined by adherens, gap and tight junctions localized between apical and apicolateral cell membranes. Tight junctions appear as zonulae occludens in the non-pigmented apicolateral cell membranes and as tight focal junctions between pigmented and non-pigmented apical cell membranes. Between the ciliary and retinal margins there are adherens and tight focal junctions which attach pigmented apical cell membranes to adjacent cells. There were no differences in the distribution of intercellular junctions between albino and pigmented rabbits. [source] | |||||||||||||