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Electron-dense Material (electron-dense + material)
Selected AbstractsElectron microscopic findings in non-alcoholic fatty liver disease: Is there a difference between hepatosteatosis and steatohepatitis?JOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 3 2010Emel Ahishali Abstract Background and Aims:, Non-alcoholic fatty liver disease has long been accepted as benign; however, recent evidence suggests that the disease may progress to cirrhosis and hepatocellular carcinoma, although the natural course of the disease is still unclear. This study was designed to comparatively evaluate electron microscopic features of non-alcoholic fatty liver (NAFL) and non-alcoholic steatohepatitis (NASH). Methods:, Quantitative and semi-quantitative ultrastructural evaluations were performed on liver biopsies from 23 patients, 10 with NAFL and 13 with NASH. Results:, No statistically significant difference was noted between NAFL and NASH patients in ultrastructural features of hepatocytes including megamitochondria, intramitochondrial crystalline inclusions, mitochondrial matrix granules, foamy cytoplasmic appearance, electron-lucent and glycogen-containing nuclear regions, lipofuscin granules, or an increased frequency of vesicles containing electron-dense material in peribiliary Golgi zone; however, the mitochondrial diameter was significantly higher in the NASH patients. Intercellular distance and microvilli between hepatocytes, collagen and electron-dense material accumulation in the space of Disse, electron-dense material accumulation and microvillus density in bile canaliculi did not differ significantly between the groups. Conclusions:, Our data show that, although NAFL and NASH can be distinguished by their distinct light microscopic features, ultrastructural characteristics are similar, which suggests that NAFL may also have the potential to progress to fibrosis and cirrhosis like NASH. [source] Reproductive morphology of Brittanichthys axelrodi (Teleostei: Characidae), a miniature inseminating fish from South AmericaJOURNAL OF MORPHOLOGY, Issue 1 2007Robert Javonillo Abstract Light and electron microscopy were used to investigate the morphology of reproductive characters in a characid fish, Brittanichthys axelrodi. Spermatozoa were found in ovaries of females, thereby confirming insemination in this species. Bony hooks can be found on the fourth unbranched ray and branched rays 1,4 of the anal fin and the unique sigmoidally-curved ray of the caudal fin in mature males. Testes have three distinct regions: an anterior spermatogenic region, an aspermatogenic middle region lined with a simple squamous epithelium and used for storage of mature spermatozoa, and a posterior region of coiled chambers lined with a high simple cuboidal epithelium. The most posterior region appears to be instrumental in the formation and storage of spermatozeugmata, unencapsulated sperm packets. Thus far, this tripartite testis morphology is unique among characids. The mature spermatozoon has an elongate nucleus (,5 ,m in length). A striated rootlet originates at the anterior end of the distal centriole and continues to the anterior tip of the cell. The striated rootlet wraps around the entire ventral area of the anterior part of the nucleus and appears to continue around the anterior tip of the nucleus and down the dorsal side as electron-dense material. Several large, spherical mitochondria (,0.6 ,m in diameter) with lamellar cristae overlap the posterior end of the nucleus and continue beyond together with the cytoplasmic collar that contains the flagellum which lacks axonemal fins. Each spermatozeugma is lanceolate in shape when sectioned mid-sagitally, with the core staining positively for mucopolysaccharides. In both sexes, the gonopore opens posterior to the anus, with the urinary pore having a separate opening posterior to the gonopore. Bands of skeletal muscle were found in the area of the male gonopore. These morphological features are likely linked to the reproductive mode of insemination, a trait that is so far as known, relatively rare among teleost fishes, but is proving increasingly frequent among certain groups of characid fishes. J. Morphol, 2006. © 2006 Wiley-Liss, Inc. [source] Spatial organization and isotubulin composition of microtubules in epidermal tendon cells of Artemia franciscanaJOURNAL OF MORPHOLOGY, Issue 2 2005Godelieve R.J. Criel Abstract Epidermally derived tendon cells attach the exoskeleton (cuticle) of the Branchiopod crustacean, Artemia franciscana, to underlying muscle in the hindgut, while the structurally similar transalar tendon (epithelial) cells, which also arise from the epidermis and are polarized, connect dorsal and ventral exopodite surfaces. To establish these latter attachments the transalar tendon cells interact with cuticles on opposite sides of the exopodite by way of their apical surfaces and with one another via basal regions, or the cuticle attachments may be mediated through linkages with phagocytic storage cells found in the hemolymph. In some cases, phyllopod tendon cells attach directly to muscle cells. Tendon cells in the hindgut of Artemia possess microtubule bundles, as do the transalar cells, and they extend from the basal myotendinal junction to the apical domain located near the cuticle. The bundled microtubules intermingle with thin filaments reminiscent of microfilaments, but intermediate filament-like structures are absent. Microtubule bundles converging at apical cell surfaces contact structures termed apical invaginations, composed of cytoplasmic membrane infoldings associated with electron-dense material. Intracuticular rods protrude from apical invaginations, either into the cuticle during intermolt or the molting fluid in premolt. Confocal microscopy of immunofluorescently stained samples revealed tyrosinated, detyrosinated, and acetylated tubulins, the first time posttranslationally modified isoforms of this protein have been demonstrated in crustacean tendon cells. Microfilaments, as shown by staining with phalloidin, coincided spatially with microtubule bundles. Artemia tendon cells clearly represent an interesting system for study of cytoskeleton organization within the context of cytoplasmic polarity and the results in this article indicate functional cooperation of microtubules and microfilaments. These cytoskeletal elements, either acting independently or in concert, may transmit tension from muscle to cuticle in the hindgut and resist compression when connecting exopodite cuticular surfaces. © 2004 Wiley-Liss, Inc. [source] Expression of the hepatitis C virus structural proteins in mammalian cells induces morphology similar to that in natural infectionJOURNAL OF VIRAL HEPATITIS, Issue 1 2002S. J. Greive Like many positive-strand RNA viruses, replication of the hepatitis C virus (HCV) is associated with cytoplasmic membrane rearrangements. However, it is unclear which HCV proteins induce these ultrastructural features. This work examined the morphological changes induced by expression of the HCV structural proteins, core, E1 and E2, expressed from a Semliki Forest Virus (SFV) recombinant RNA replicon. Electron microscopy of cells expressing these proteins showed cytoplasmic vacuoles containing membranous and electron-dense material that were distinct from the type I cytoplasmic vacuoles induced during SFV replicon replication. Immunogold labelling showed that the core and E2 proteins localized to the external and internal membranes of these vacuoles, but at times were also associated with some of the internal amorphous material. Dual immunogold labelling with antibodies raised against the core protein and against an endoplasmic reticulum (ER)-resident protein (protein disulphide isomerase) showed that the HCV-induced vacuoles were associated with ER-labelled membranes. This report has identified an association between the HCV core and E2 proteins with induced cytoplasmic vacuoles which are morphologically similar to those observed in HCV-infected liver tissue, suggesting that the HCV structural proteins may be responsible for the induction of these vacuoles during HCV replication in vivo. [source] Ultrastructural features of bone marrow cells from patients with acquired sideroblastic anemiaMICROSCOPY RESEARCH AND TECHNIQUE, Issue 3 2004Meir Djaldetti Abstract The ultrastructural findings of the bone marrow cells from 15 patients with acquired sideroblastic anemia are presented. The red cell precursors from all patients showed the presence of electron-dense material in the mitochondria, representing most probably iron deposits. A great number of these mitochondria were completely destroyed. The erythropoietic precursors from one of the patients showed markedly elongated mitochondria that measured up to 3 ,m. In addition numerous cytoplasmic vacuoles were observed. The red cell precursors from 60% of the patients showed signs of dyserythropoiesis, such as incomplete nuclear division and nuclear distortion. The polymorphonuclears from 47% of the patients presented nuclear abnormalities expressed as nuclear bridges, appendices, and blebs. In addition, phagocytosis of red blood cells was observed. The results of the study underline the advantages of the transmission electron microscope examination in visualization of intricate alterations in hematopoietic cells that cannot be detected with a light microscope. Microsc. Res. Tech. 63:155,158, 2004. © 2004 Wiley-Liss, Inc. [source] Bunina bodies in amyotrophic lateral sclerosisNEUROPATHOLOGY, Issue 2 2008Koichi Okamoto Bunina bodies, which are small eosinophilic intraneuronal inclusions in the remaining lower motor neurons, are generally considered to be a specific pathologic hallmark of amyotrophic lateral sclerosis (ALS). One year before a publication by Bunina, van Reeth et al. described similar intracytoplasmic inclusions in the anterior horn cells in a patient with Pick's dementia with atypical ALS. At present, only two proteins have been shown to be present in Bunina bodies, one is cystatin C and the other is transferrin. Bunina bodies consist of amorphous electron-dense material surrounded by tubular and vesicular structures on electron microscopy. Although the nature and significance of Bunina bodies in ALS are not yet clear, the bodies may be abnormal accumulations of unknown proteinous materials. [source] Re-examination of ultrastructures of the stellate chloroplast organization in brown algae: Structure and development of pyrenoidsPHYCOLOGICAL RESEARCH, Issue 3 2007Atsuko Tanaka SUMMARY Some taxa of brown algae have a so-called ,stellate' chloroplast arrangement composed of multiple chloroplasts arranged in a stellate configuration, or else a single chloroplast with radiating lobes. The fine structures of chloroplasts and pyrenoids have been studied, but the details of their membrane configurations as well as pyrenoid ontogeny have not been well understood. The ultrastructure of the single stellate chloroplast in Splachnidium rugosum and Scytothamnus australis were re-examined in the present study, as well as the stellate arrangement of chloroplasts in Asteronema ferruginea and Asterocladon interjectum, using freeze-substitution fixation. It was confirmed that the chloroplast envelope invaginated into the pyrenoid in Splachnidium rugosum, Scytothamnus australis and Asteronema ferruginea, but chloroplast endoplasmic reticulum (CER) remained on the surface of the chloroplast. The space between the invaginated chloroplast envelope and CER was filled with electron-dense material. In Asteronema ferruginea, CER surrounding each pyrenoid was closely appressed to the neighboring CER over the pyrenoids, so that the chloroplasts formed a stellate configuration; however, in the apical cells chloroplasts formed two or more loose groups, or were completely dispersed. The pyrenoids of Asterocladon interjectum did not have any invagination of the chloroplast envelope, but a unique membranous sac surrounded the pyrenoid complex and occasionally other organelles (e.g. mitochondria). Immunolocalization of ,-1,3-glucans showed that the membranous sac in Asterocladon interjectum did not contain photosynthetic products such as chrysolaminaran. Observations in the dividing cells of Splachnidium rugosum and Scytothamnus australis indicated that the pyrenoid in the center of the chloroplast enlarged and divided into two before or during chloroplast division. [source] The circulative pathway of begomoviruses in the whitefly vector Bemisia tabaci, insights from studies with Tomato yellow leaf curl virusANNALS OF APPLIED BIOLOGY, Issue 3 2002HENRYK CZOSNEK Summary Our current knowledge concerning the transmission of begomoviruses by the whitefly vector Bemisia tabaci is based mainly on research performed on the Tomato yellow leaf curl virus (TYLCV) complex and on a number of viruses originating from the Old World, such as Tomato leaf curl virus, and from the New World, including Abutilon mosaic virus, Tomato mottle virus, and Squash leaf curl virus. In this review we discuss the characteristics of acquisition, transmission and retention of begomoviruses by the whitefly vector, concentrating on the TYLCV complex, based on both published and recent unpublished data. We describe the cells and organs encountered by begomoviruses in B. tabaci. We show immunolocalisation of TYLCV to the B. tabaci stylet food canal and to the proximal part of the descending midgut, and TYLCV-specific labelling was also associated with food in the lumen. The microvilli and electron-dense material in the epithelial cells of the gut wall were also labelled by the anti TYLCV serum, pointing to a possible virus translocation route through the gut wall and to a putative site of long-term virus storage. We describe the path of begomoviruses in their vector B. tabaci and in the non-vector whitefly Trialeurodes vaporariorum, and we follow the rate of virus translocation in these insects. We discuss TYLCV transmission between B. tabaci during mating, probably by exchange of haemolymph. We show that following a short acquisition access to infected tomato plants, TYLCV remains associated with the B. tabaci vector for weeks, while the virus is undetectable after a few hours in the non-vector T. vaporariorum. The implications of the long-term association of TYLCV with B. tabaci in the light of interactions of the begomovirus with insect receptors are discussed. [source] Disruption of tight junction structure in salivary glands from Sjögren's syndrome patients is linked to proinflammatory cytokine exposureARTHRITIS & RHEUMATISM, Issue 5 2010Patricia Ewert Objective Disorganization of acinar cell apical microvilli and the presence of stromal collagen in the acinar lumen suggest that the labial salivary gland (LSG) barrier function is impaired in patients with Sjögren's syndrome. Tight junctions define cell polarity and regulate the paracellular flow of ions and water, crucial functions of acinar cells. This study was undertaken to evaluate the expression and localization of tight junction proteins in LSGs from patients with SS and to determine in vitro the effects of tumor necrosis factor , (TNF,) and interferon-, (IFN,) on tight junction integrity of isolated acini from control subjects. Methods Twenty-two patients and 15 controls were studied. The messenger RNA and protein levels of tight junction components (claudin-1, claudin-3, claudin-4, occludin, and ZO-1) were determined by semiquantitative reverse transcriptase,polymerase chain reaction and Western blotting. Tight junction protein localization was determined by immunohistochemistry. Tight junction ultrastructure was examined by transmission electron microscopy. Isolated acini from control subjects were treated with TNF, and IFN,. Results Significant differences in tight junction protein levels were detected in patients with SS. ZO-1 and occludin were strongly down-regulated, while claudin-1 and claudin-4 were overexpressed. Tight junction proteins localized exclusively to apical domains in acini and ducts of LSGs from controls. In SS patients, the ZO-1 and occludin the apical domain presence of decreased, while claudin-3 and claudin-4 was redistributed to the basolateral plasma membrane. Exposure of isolated control acini to TNF, and IFN, reproduced these alterations in vitro. Ultrastructural analysis associated tight junction disorganization with the presence of endocytic vesicles containing electron-dense material that may represent tight junction components. Conclusion Our findings indicate that local cytokine production in LSGs from SS patients may contribute to the secretory gland dysfunction observed in SS patients by altering tight junction integrity of epithelial cells, thereby decreasing the quality and quantity of saliva. [source] Vegetative Storage Protein with Trypsin Inhibitor Activity Occurs in Sapindus mukorassi, a Sapindaceae Deciduous TreeJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 4 2009Shi-Biao Liu Abstract A vegetative storage protein (VSP) with trypsin inhibitor activity in a deciduous tree, Sapindus mukorassi, was characterized by means of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western-blot, immuno-histochemical localization, light- and electro-microscopy, together with analysis of proteinase inhibitor activity of the purified VSP in vitro. There were two proteins with molecular masses of about 23 and 27 kDa in a relatively high content in the bark tissues of terminal branches of S. mukorassi in leafless periods. The proteins decreased markedly during young shoot development, indicating their role in seasonal nitrogen storage. Immuno-histochemical localization with the polyclonal antibodies raised against the 23 kDa protein demonstrated that the 23 kDa protein was the major component of protein inclusions in protein-storing cells. The protein inclusions were identified by protein-specific staining and should correspond to the electron-dense materials in different forms in the vacuoles of phloem parenchyma cells and phloem ray parenchyma cells under an electron microscope. So, the 23 kDa protein was a typical VSP in S. mukorassi. The 23 and 27 kDa proteins shared no immuno-relatedness, whereas the 23 kDa protein was immuno-related with the 22 kDa VSP in lychee and possessed trypsin inhibitor activity. The 23 kDa protein may confer dual functions: nitrogen storage and defense. [source] | |||||||||||||