bluuebunny/crossref_metadata_2025 huggingface dataset:
Cryoelectron microscopy of complexes of human rhinovirus with a monoclonal FAB and the viral cellular receptor
Authors: Olson Norman H. , Smith Thomas J. , Kolatkar Prasanna R. , Oliveira Marcos A. , Rueckert Roland R. , Greve Jeffrey M. , Rossmann Michael G. , Baker Timothy S.
Published: June 2020

Cryo-electron microscopy and image analysis techniques make it possible to study structural and functional relationships of macromolecular complexes that currently are not easily examined with crystallographic techniques. We have recorded images of frozen-hydrated human rhinovirus serotype-14 (HRV-14) complexed with a neutralizing, monoclonal, antibody fragment (Fab-17Ia; Fig. 1 A); and HRV-16 complexed with the amino-terminal, two-domain fragment (D1D2) of its cellular receptor (intercellular adhesion molecule-1, ICAM-1; Fig. 1B). Three-dimensional reconstructions (Figs. 2A,B) were calculated to ∽3nm resolution from 35 and 44 images of each complex, respectively. The HRV-14/Fab structure clearly identified the footprint of the Fab on the surface of the virion. The HRV-16/D1D2 reconstruction presents, for the first time, the three-dimensional structure of a complete virus complexed with its cellular receptor.
The microtubule associated protein (MAP) tau forms a new class of triple-stranded left-hand helical fibrous protein polymer
Authors: Ruben G. C. , Iqbal K. , Grundke-Iqbal I. , Wisniewski H. , Ciardelli T. L. , Johnson J. H.
Published: June 2020

In neurons, the microtubule associated protein, tau, is found in the axons. Tau stabilizes the microtubules required for neurotransmitter transport to the axonal terminal. Since tau has been found in both Alzheimer neurofibrillary tangles (NFT) and in paired helical filaments (PHF), the study of tau's normal structure had to preceed TEM studies of NFT and PHF. The structure of tau was first studied by ultracentrifugation. This work suggested that it was a rod shaped molecule with an axial ratio of 20:1. More recently, paraciystals of phosphorylated and nonphosphoiylated tau have been reported. Phosphorylated tau was 90-95 nm in length and 3-6 nm in diameter where as nonphosphorylated tau was 69-75 nm in length. A shorter length of 30 nm was reported for undamaged tau indicating that it is an extremely flexible molecule. Tau was also studied in relation to microtubules, and its length was found to be 56.1±14.1 nm.
Ultrastructural analysis of the spatial distribution of MRNA
Authors: Bassell Gary , Singer Robert H.
Published: June 2020

We have been investigating the spatial distribution of nucleic acids intracellularly using in situ hybridization. The use of non-isotopic nucleotide analogs incorporated into the DNA probe allows the detection of the probe at its site of hybridization within the cell. This approach therefore is compatible with the high resolution available by electron microscopy. Biotinated or digoxigenated probe can be detected by antibodies conjugated to colloidal gold. Because mRNA serves as a template for the probe fragments, the colloidal gold particles are detected as arrays which allow it to be unequivocally distinguished from background.
Ultrastructural analysis of early pre-messenger RNA processing events using the Miller chromatin spreading method
Authors: Beyer Ann , Osheim Yvonne
Published: June 2020

We use the Miller chromatin spreading technique for electron microscopic visualization of transcriptionally active genes. In this method, cells are hypotonically disrupted and cellular contents are diluted into water at pH 8-9 and fixed with formaldehyde. The dispersed cellular contents are centrifuged onto a carbon-coated EM grid; the majority of the material that is deposited on the grid consists of entangled masses of dispersed chromatin, some regions of which are transcriptionally active (Fig 1). Our interests lie in ultrastructural analysis of co-transcriptional RNA processing events on pre-mRNA transcripts, which we analyze by mapping structural features on successive nascent transcripts on a given gene. The two processing events that we have been able to study by this approach are the removal of introns by splicing and generation of the 3’ end of the transcript.
Ciliary coordination in newt lung cells requires microtubule-based linkages between basal bodies: A correlative light and EM study
Authors: Hard Robert , Rupp Gerald , Withiam-Leitch Matthew L. , Cardamone Lisa
Published: June 2020

In a coordinated field of beating cilia, the direction of the power stroke is correlated with the orientation of basal body appendages, called basal feet. In newt lung ciliated cells, adjacent basal feet are interconnected by cold-stable microtubules (basal MTs). In the present study, we investigate the hypothesis that these basal MTs stabilize ciliary distribution and alignment. To accomplish this, newt lung primary cultures were treated with the microtubule disrupting agent, Colcemid. In newt lung cultures, cilia normally disperse in a characteristic fashion as the mucociliary epithelium migrates from the tissue explant. Four arbitrary, but progressive stages of dispersion were defined and used to monitor this redistribution process. Ciliaiy beat frequency, coordination, and dispersion were assessed for 91 hrs in untreated (control) and treated cultures. When compared to controls, cilia dispersed more rapidly and ciliary coordination decreased markedly in cultures treated with Colcemid (2 mM). Correlative LM/EM was used to assess whether these effects of Colcemid were coupled to ultrastructural changes. Living cells were defined as having coordinated or uncoordinated cilia and then were processed for transmission EM.
3D x-ray microscopy with a storage phosphor plate detector
Authors: Johnson Roger H. , Fisher Robert M. , Nelson Alan C.
Published: June 2020

X-ray microscopy provides the ability to obtain transmission, micron-order spatial resolution images of thick, wet objects at atmospheric pressure, e.g. to image some living specimens under dynamic conditions. Past excitement in the field was dulled by difficulties in extracting desirable information from the vast amount of data which gets superimposed on an integrating planar detector such as film. Tomographic techniques such as backprojection reconstruction and laminography can solve the detail superimposition problem. Recent advances in solid state detectors facilitate the timely acquisition of multiple images required for tomographic imaging. We report here on our x-ray source and detector characteristics as well as initial planar microscopy and 3D imaging results from our ongoing development of a low-cost x-ray microtomograph.
Ultrastructural three-dimensional reconstruction of a T lymphocyte
Authors: Bovard Karen K. , Marcus Joseph N.
Published: June 2020

There have been many electron microscopy studies of normal and neoplastic lymphocyte microanatomy. However, only a few use three-dimensional analysis techniques to visualize organelle relationships, such as nuclear shape and chromatin distribution, nucleolar organizing regions, and, by high voltage electron microscopy, the microtubular networks over a limited depth though the cell. To date, there has been no three-dimensional serial reconstuction of a T Lymphocyte and its organelles.
In vivo targeting of erythrocytes to circulating T-cells
Authors: Chiarantini Laura , Droleskey Robert E. , DeLoach John R.
Published: June 2020

The use of carrier erythrocytes to specifically deliver toxic drugs to cancer cells has been a continuing effort in many laboratories. Carrier erythrocytes offer the advantages of having a large volume, are biodegradable, are easily obtained and prepared, and have the capability of circulating as well as normal erythrocytes. The selectivein vivotargeting of drug loaded carrier erythrocytes to the liver and spleen has been demonstrated. By the use of intraperitoneal (IP) injection of carrier erythrocytes DeLoach et al. have demonstrated that carrier erythrocytes can not only be targeted to the lymphatic system but to normal circulation as well. In an attempt to determine the feasibility of targeting carrier erythrocytes to circulating murine T-cells we coupled a monoclonal antibody (Mab) (antimouse Thy 1.2) to murine erythrocytes using chromic chloride as a coupling agent. Murine erythrocytes coupled with antimouse Thy 1.2 have been shown to form rosettes with a cytotoxic T-lymphocyte line (CTLL)in vitro.
Electron microscopic and electron probe x-ray microanalysis (EPXMA) of prostatic intraluminal “crystalloids”
Authors: Bui H.X. , delRosario A. , Abdulla M. , Sheehan C.E. , Emerson R.J. , Singh J. , Ross J.S.
Published: June 2020

Prostatic intraluminal “crystalloids” are intensely eosinophilic, non-birefringent crystalline-like structures readily identified with light microscopy. Well documented to be associated with prostatic adenocarcinoma, these rhomboidal, hexagonal, triangular, polyhedral, or needle-like structures are almost exclusively confined to well differentiated prostatic adenocarcinomas and may occasionally be seen in adjacent benign glands bordering the tumors. Although of significant potential as a signal of nearby cancer in a limited biopsy of benign prostate, these “crystalloids” are poorly defined and their chemical composition has not been determined.
Ultrastructural characterization of murine Fcε RI-bearing cells in IL-3 dependent bone marrow cultures with and without stem cell factor
Authors: Goff J.P. , Rottem M. , Albert J.P. , Metcalfe D. D.
Published: June 2020

It is known that mast cells arise from pluripotent hematopoietic progenitor cells and express their mature phenotypes in tissues (1,2). Information concerning the early development of mast cells and basophils is limited and the sequence of events involved in maturation is incompletely understood. Mast cells and basophils are unique in that they are the only cells known so far to express high-affinity receptors for IgE (Fc∊ RI) on their surface (3). They are characterized in part, by both the presence of these receptors and metachromatic cytoplasmic granules that contain histamine. At early stages of development the distinction between mast cells and basophils by light microscopy is very difficult. Since mast cells and basophils express different biochemical and functional properties, accurate identification is essential for understanding the role these cells play in health and disease.
Ultrastructural autoradiography of L6 skeletal-muscle cells exposed to a tritiated macrolide antibiotic (LY237216) in vitro
Authors: White S.L. , Jensen C.B. , Giera D.D. , Laska D.A. , Novilla M.N. , Hoover D.M.
Published: June 2020

In vitro exposure to LY237216 (9-Deoxo-11-deoxy-9,11-{imino[2-(2-methoxyethoxy)ethylidene]-oxy}-(9S)-erythromycin), a macrolide antibiotic, was found to induce cytoplasmic vacuolation in L6 skeletal muscle myoblast cultures (White, S.L., unpubl). The present study was done to determine, by autoradiographic quantitative analysis, the subcellular distribution of 3H-LY237216 in L6 cells.

L6 cells (ATCC, CRL 1458) were cultured to confluency on polycarbonate membrane filters (Millipore Corp., Bedford, MA) in M-199 medium (GIBCO® Labs) with 10% fetal bovine serum. The cells were exposed from the apical surface for 1-hour to unlabelled-compound (0 μCi/ml) or 50 (μCi/ml of 3H-LY237216 at a compound concentration of 0.25 mg/ml. Following a rapid rinse in compound-free growth medium, the cells were slam-frozen against a liquid nitrogen cooled, polished copper block in a CF-100 cryofixation unit (LifeCell Corp., The Woodlands, TX). Specimens were dried in the MDD-C Molecular Distillation Drier (LifeCell Corp.), vapor osmicated and embedded in Spurrs low viscosity resin. Ultrathin sections collected on formvar coated stainless steel grids were counter-stained, then individually mounted on corks. A monolayer of Ilford L4 nuclear emulsion (Polysciences, Inc., Warrington, PA) was placed on the sections, utilizing a modified “loop method”. The emulsions were exposed for 7-weeks in a light-tight box at 4°C. Autoradiographs were developed in Microdol-X developer and examined on a Philips EM410LS transmission electron microscope. Quantitative analysis of compound localization employed the point and circle approach of Williams; incorporating the probability circle method of Salpeter and McHenry.
Ultrastructural diagnosis of renal oncocytoma
Authors: Siew Shirley , Fatteh Mehboob
Published: June 2020

Renal oncocytoma is a comparatively rare tumor, having an incidence 1/20th that of renal cell carcinoma, from which it has to be differentiated. We report a case of a 61 year old man who was found to have albuminuria 100 mg/dL on a routine physical examination. A retrograde pyelogram showed splaying of the right upper pole infundibula. Two right renal tumors were shown on renal CT scan and there were multiple hypervascular masses on angiography. A right radical nephrectomy was performed. The kidney weighed 176 grains and measured 11 × 7.5 × 5 cm. There were several dark brown nodules in the upper pole, lower pole and midportion of the kidney. Some of the nodules protruded onto the cortical surface, stretching the overlying capsule, but, there was no evidence of capsular nor renal vein invasion. The largest nodule measured 4.5 × 4 × 4 cm. Histologic examination showed a distinct line of demarcation between the tumors and the normal kidney. Occasional thickened vessels were noted at the border. For the greater part, the tumor showed a tubular or acinar architecture, although the lumina of some of the tubules were narrow. The tubules were lined by large, polygonal eosinophilic cells with a granular cytoplasm. There was no evidence of nuclear atypicality nor mitotic activity. Thin walled blood vessels were present between the tubules. Transmission electron microscopy showed the presence of irregular tubules, surrounded by a well formed basement membrane. The tubules were separated by thin walled blood vessels (Fig. 1). The luminal surface of the cells lacked microvilli – Nuclei were comparatively small and irregular in shape. Lysosomes were concentrated towards the luminal surface. There were occasional lipid vacuoles. The cytoplasm contained large numbers of mitochondria with membranous cristae (Fig. 2) . These ultrastructural characteristics are in keeping with those of a renal oncocytoma. Comment: The term oncocyte1 is applied, at the light microscopic level, to large epithelial cells, which have a markedly eosinophilic and granular cytoplasm. Transmission electron microscopy shows the presence of an abundance of mitochondria filling the cytoplasm. Oncocytomas are tumors composed of a uniform population of such cells. Renal oncocytoma is considered to be a benign cortical adenoma. It has been postulated that it arises from proximal tubular epithelium. Features that distinguish renal oncocytoma from other adenomas are that they may reach a large size (7cm) and that they maybe multicentric in the same kidney (reported in 5% of cases). The dark brown bulging nodules present in our case are typical of the gross appearance of renal oncocytoma. Various theories have been proposed to account for the marked increase of mitochondria, including that it is due to a neoplastic proliferation of them, at the expense of other subcellular organelles. The diagnosis of oncocytoma is established by the ultrastructural demonstration of the abnormal abundance of mitochondria.
Ultrastructure of the lesion induced by toxin T-514 isolated from K. humboldtiana in the alveolar region of the lung
Authors: Sepúlveda-Saavedra Julio , González-Corona Beatriz , Tamez Rodríguez Víctor A. , Bermúdez de Rocha Ma. Victoria , López Alfredo Piñeyro
Published: June 2020

It has been shown in previous studies that the toxin T-514 isolated from K. humboldtiana induces severe damage to the lung in treated rodents. Histopathological findings include edema, and alveolar hemorrage. However, the ultraestructure of the lesion has not been investigated. In this study we used two species of rodents: Hamster and guinea pig, and a primate: Macaca fascicularis. Animals received different single dosis of the toxin via intraperitoneal. Control animals received only the vehicle (propylen glycol). Inmediately after spontaneous death, lung samples were fixed in Karnovsky-Ito fixative, post fixed in osmium tetroxide and embedded in epon. Thin sections were prepared with an Ultratome V LKB, stained with uranly acetate and lead citrate, and studied in an electron microscope Zeiss-EM109.
Piroximone (MDL 19,205)-induced ultrastructural and biochemical changes in early adrenal medullary proliferative disease in rats
Authors: Sprinkle-Cavallo J. , Thompson F.Y. , Loudy D.E. , Dudley M.W. , Ogden A.M. , Gibson J.P.
Published: June 2020

Piroximone is a cardiotonic agent (phosphodiesterase inhibitor) proposed for the treatment of congestive heart failure. The drug causes adrenal medullary proliferative disease (AMPD) in rats after 1 year or more of treatment. In this study we investigated the effects on adrenal chromaffin cells prior to the development of obvious hyperplasia. Male rats were administered 0, 300, or 600 mg/kg/day of piroximone in the diet for three months.

For morphometry studies, adrenals from 5 rats/group were fixed in 10% formalin and stained with hematoxylin and eosin (H&E). For differentiation of chromaffin cell types, left adrenals from 5 rats/group were fixed in 2% glutaraldehyde and 4% EM grade formaldehyde and stained with Gomori's methanamine silver and also (after pretreatment with 2.5% potassium dichromate in 1% sodium sulfate) with H&E as well as toluidine blue. For electron microscopy studies, adrenal medulla from 5 rats/group was fixed in 5% glutaraldehyde with post-fixation in 4% paraformaldehyde.
Characterization of spontaneously occurring corneal changes in Wistar rats
Authors: Baker K.W. , Wojcinski Z. , Piscopo I. , Rogers J. , Houston B. , Gragtmans B.
Published: June 2020

Spontaneously-occurring changes in the cornea have been periodically observed during routine ophthalmologic examination of various strains of mice and rats. The clinical appearance of these changes has been variably described as corneal opacities, corneal dystrophy, or corneal roughness. The purpose of this study was to characterize corneal changes in Wistar rats by light and transmission electron microscopy (LM and TEM), and x-ray microanalysis.
Application of immunogold/quantitative x-ray microanalysis to study infectious hematopoietic necrosis virus
Authors: Helmick Consetta M. , Bailey J. Franklin , Avila Jeanene De , Ristow Sandra S.
Published: June 2020

Monoclonal antibody staining followed by immunogold labeling and energy dispersive x-ray microanalysis was utilized to detect the presence of the nucleoprotein (N) and glycoprotein (G) of infectious hematopoietic necrosis virus (IHNV) on the surface of cultured coho salmon embryo (CSE-119) and rainbow trout heart (RTH) cell lines. The objectives of this study were to first, demonstrate that anti-G and anti-N monoclonal antibodies labeled with streptavidin gold would identify virus bound to the surface of cultured fish cells. Secondly, we sought to demonstrate the quantities of colloidal gold particles associated with the surface region of IHNV infected cells at 1, 4, 6, 8, 14, 24, and 30 hours.
Ultrastructural evidence of sink function of central canal of spinal cord as demonstrated by clearance of horseradish peroxidase
Authors: Milhorat T.H. , Nakamura S. , Heger I. , Nobandegani F. , Murray S.
Published: June 2020

It has been recently reported that when Evan’s blue dye is microinjected into the spinal cord, or when it is injected into blood following freeze lesioning of the spinal cord, the marker passes rapidly from the parenchyma into the central canal, and drains rostrally to the fourth ventricle. This pattern of clearance is similar to the clearance of blood and blood products in experimental hematomyelia, and suggests that the central canal functions as a sink for the extracellular compartment of the spinal cord.
Regional differentiation of the malpighian tubules of Pieris canidia larva: An electron microscopic study
Authors: Cheung W.W.K. , Wang J.B.
Published: June 2020

Malpighian tubules in insects arose primarily for the purpose of hydromineral regulation. In the small cabbage white Pieris canidia larva there are six tubules, with three on each side of the body. Together with the common cabbage white Pieris brassicae larva they are frequently encountered pests on cruciferous plants. Although physiological studies on the functions of Pieris brassicae larval malpighian tubules have been well documented, detailed ultrastructural studies on these tubules have not been thoroughly studied. For the sake of further understanding on how these malpighian tubules function an electron microscopic study of different regions of the malpighian tubules of Pieris canidia have been carried out.
SEM analysis of fish scale cross sections: A technique study
Authors: Lee M.E. , Moller A. , Fouche P.S.O. , Gaigher I.G
Published: June 2020

Scanning electron microscopy of fish scales has facilitated the application of micro-structures to systematics. Electron microscopy studies have added more information on the structure of the scale and the associated cells, many problems still remain unsolved, because of our incomplete knowledge of the process of calcification. One of the main purposes of these studies has been to study the histology, histochemistry, and ultrastructure of both calcified and decalcified scales, and associated cells, and to obtain more information on the mechanism of calcification in the scales. The study of a calcified scale with the electron microscope is complicated by the difficulty in sectioning this material because of the close association of very hard tissue with very soft tissues. Sections often shatter and blemishes are difficult to avoid. Therefore the aim of this study is firstly to develop techniques for the preparation of cross sections of fish scales for scanning electron microscopy and secondly the application of these techniques for the determination of the structures and calcification of fish scales.
A Langendorf preparation for quick-freezing small hearts
Authors: Sommer Joachim , High Teresa , Ingram Peter , Nassar Rashid , Shepherd Neal
Published: June 2020

The validity of studies of cell structures at high spatial and temporal resolution depends on the fidelity with which tissue preparation maintains in vivo conditions. Optimal preservation of structural substrates of precisely timed physiological intracellular events is offered by cryopreservation followed by freeze-fracture and freeze-substitution; we have established criteria for gauging that quality of cryopreservation in skeletal and cardiac muscle. Ciyopreservation is indispensable for electron probe x-ray microanalysis (EPXMA) of freeze-dried cryosections. We have developed a Langendorf preparation for small hearts (Figs. 1,2) suitable for use in our quick-freeze device (“Cryopress”; Med-Vac, Inc., St. Louis, MO 63117) to a) investigate the spatial distribution of physiologically important elements (e.g. calcium) during excitation-contraction coupling (ECC), especially in intact avian hearts and, b) assess damage to cardiac ultrastructure that is caused by pathological conditions (e.g. ischemia), rather than by artifacts due to chemical fixation (e.g. membrane damage by glutaraldehyde). In our Langendorf preparation, the tips of hearts can be quick-frozen at optimal freezing conditions, and comparative studies of the hearts of different animal species performed.
In situ microtomy and serial block face imaging by SEM
Authors: Kuzirian Alan M. , Leighton Stephen B.
Published: June 2020

The ability to view objects, including subcellular structures, in three-dimensions is crucial to understanding their form and function. For example, the three-dimensional (3-D) structure of the brain and its neurons has been the central focus of neuroanatomists for well over 100 years. Yet, what role a nerve cell’s three dimensional structure plays in controlling the flow of information within the nervous system remains a mystery. Part of the problem has been the difficulty in obtaining an accurate 3-D picture of a nerve cell’s shape as well as documenting its synaptic interconnections. Although many neurobiologists have turned to biochemical studies in recent years, it is becoming clear that precise structure and network diagrams will be necessary to relate the work of cell biologists with that of computational neuroscientists.
Microscopic evaluation of structural changes in brittle, hydrated, gelatin capsules
Authors: Robson J. , Snow G. , Park J.Y. , Moretz R.C. , Krenkel H.-O. , Angel A.
Published: June 2020

Gelatin capsules are a commonly used dosage form for prescription medications. Storage conditions as well as drug formulation can directly affect capsule integrity over time. Often, capsule brittleness following storage can be related to water loss. In this report an encapsulated drug formulation containing 77% anhydrous citric acid became brittle following two years of storage at 25° C/60% RH. However, Thermogravimetric data showed that capsule brittleness did not result from changes in water content. Both normal(without drug formulation) and brittle capsules contained 12% water. Microscopy was then applied to examine capsule walls to determine if the change in physical integrity could be related to a structural change.

LM of normal capsules showed both the interior and exterior walls to be smooth, without indentations. SEM examination of the interior wall of the normal capsules revealed fairly smooth walls (Fig. 1). Sections of normal capsules examined with the TEM revealed intact walls with little variation between sections or capsules (Fig. 2). Examination of capsules stored for one year revealed interior surfaces stippled with particulate identified as active ingredient(AI) and citric acid. The particulate was not fused to the interior wall and no morphological changes were observed for the Al or citric acid when compared to known active/excipient morphology. In contrast, the interior wall of capsules stored for two years showed striking morphological changes. LM presented an eroded interior wall indicating a loss or redistribution of gelatin. TEM further illustrated that the structure of the capsule had been altered; subsurface pockets were seen throughout the section of the capsule (Fig. 3). TiO2 particles, a whitener used in the capsules, were redistributed in the areas where degradation was apparent. SEM presented irregular interior surfaces with abundant particulate fused to the capsule wall (Fig. 4). The fused particulate presented structure which contrasted with the known morphology of the citric acid and Al starting materials indicating that dissolution and recrystallization had taken place. Comparable crystal structure was determined when Al and citric acid were dissolved in water and allowed to recrystallize at room temperature.
Cytochemical detection of gene expression: Light and electron microscope evaluation of bacterial β-galactosidase reaction product
Authors: Liu Hsiao-Sheng , Cardell Emma Lou , Stambrook Peter , Cardell Robert R.
Published: June 2020

Recombinant DNA technology allows the introduction of genes into the genome of cells in vitro and in vivo. “Reporter” genes cotransfected with other genes of interest indicate successful transfection because cellular expression can be detected by histochemistry, autoradiography, or in situ hybridization histochemistry. The Escherichia coli gene, lacZ, is a frequently used reporter gene because it does not affect the usual functions or activities of the cell; the gene is present and expressed in successive generations; and bacterial β-galactosidase (β-gal), the enzyme produced as a result of expression of the gene, can be detected cytochemically. Studies that evaluate transfected cells among mixed cell populations in vivo, e.g. gene therapy and cell lineage studies, can benefit from the detectability of the cytochemical reaction product at the light and electron microscope levels. After incubation at pH 7.4 in X-gal (5-bromo-4-chloro-3 indolyl-β-D-galactoside), a commercially available indigogenic substrate, a blue-green reaction product results in cells that have synthesized functional bacterial β-galactosidase enzyme. This reaction product is visible in intact cells, and is retained during processing and embedment for thin section analysis in the transmission electron microscope. This report demonstrates the value of lacZ as a reporter gene using a clone of transfected HTD114 cells of human fibrosarcoma origin, selected for their high lacZ expression. Figure 1 is a dark field image of reaction product in 1 μm thick epon sections of cells that were incubated in X-gal, fixed, pelleted, osmicated, dehydrated, and embedded by routine methods. Figure 2 shows the appearance of the reaction product at the ultrastructural level. At both LM and EM levels, the reaction product varies in quantity among cells; appears focally concentrated in some cells, diffuse in others; and is confined to the cytosome with a noticeable ring-like distribution around the nucleus in yet other cells. Dark field analysis of sections is especially helpful for detecting relatively low quantities of reaction product. The distinctive ultrastructural appearance of the reaction product allows the unequivocal identification of cells expressing lacZ as well as the ultrastructural features of the cells. Ultrastructural characterization of the cell is often important for precise identification of cell type, especially in tissues such as lung in which there are many different cell types.
Localization of hydrogen peroxide and serum albumin in experimental optic neuritis: Combined cytochemistry amd immunocytochemistry
Authors: Ellis E. Ann , Guy John R.
Published: June 2020

The oxidant, hydrogen peroxide (H2O2), is discharged by inflammatory cells that infiltrate the central nervous system and has been shown to play a role in disruption of the blood-brain barrier (BBB) and demyelination in the optic neuritis of experimental allergic encephalomyelitis (EAE)1, an animal model for multiple sclerosis (MS). Alterations in the BBB and vascular permeability in EAE have been studied with exogenous, injected tracers; but there have been no studies of native, endogenous proteins. In order to study the role of oxidants in vascular permeability in EAE, we localized H2O2 at the ultrastructural level followed by immunocytochemical localization of endogenous serum albumin in the optic nerves of guinea pigs sensitized to EAE.
Immunocytochemical localization of nitrogen oxide synthase, NADPH diaphorase and soluble guanylyl cyclase in neuronal and non-neuronal tissues of the rat
Authors: Gagne Gerard D. , Schmidt Harald H.H.W. , Miller Mahlon F.
Published: June 2020

Nitrinergic signal transduction involves two protein components, NO synthase (NOS) types I-III, which form nitrogen oxides (NO) from L-arginine and soluble guanylyl cyclase (GC-S), which is activated by NO and catalyzes the conversion of GTP to cyclic GMP. A polyclonal antiseruzn (6761-8) to rat cerebellar type I NOS and a monoclonal antibody to rat lung GC-S (B4) were generated in order to localize both signal transduction proteins in various rat tissues. NOS was also visualized by its NADPH-diaphorase (NADPH-d) properties through NADPH-dependent nitroblue tetrazolium (NBT) formazan formation.
Ca++-ATPase activity in the hepatopancreas cells ofOniscus asellus
Authors: Vernon G.M. , Surace A. , Witkus R.
Published: June 2020

The hepatopancreas consists of a pair of bilobed tubules comprised of two epithelial cell types. S cells are absorptive and accumulate metals such as copper and zinc. Ca++concentrations vary between the S and B cells and during the molt cycle. Roer and Dillaman implicated Ca++-ATPase in calcium transport during molting inCarcinus maenas. This study was undertaken to compare the localization of Ca++-ATPase activity in the S and B cells during intermolt.
Ultrastructural pathology and immunohistochemistry of mustard gas lesion
Authors: Petrali J.P. , Oglesby S.B. , Hamilton T.A. , Mills K.R.
Published: June 2020

The ultrastructural pathology of sulfur mustard gas (HD) skin toxicity has been documented for several model systems. In animal models, development of skin basal cell nuclear pathology was followed by progressive cytoplasmic changes leading to cell death. These cellular changes along with a disabling of hemidesmosomes at the lamina lucida were persistent features leading to the formation of characteristic microblisters at the dermal-epidermal junction.In this paper we correlate an ultrastructural pathologic study of HD exposed hairless guinea pig skin with a companion immunohistochemical study describing HD effects on extra-cellular structural proteins of the dermal-epidermal junction. The structural proteins summarized for this report are bullous pemphigoid antigen and laminin.
Effect of acid deposition on trichome morphology and dogwood anthracnose biology
Authors: Thornham Kyle T. , Stipes R. Jay , Grayson Randolph L.
Published: June 2020

Dogwood anthracnose, caused by Discula destructiva (1), is another new catastrophic tree disease that has ravaged natural populations of the flowering dogwood (Cornus florida) in the Appalachians over the past 15 years, and the epidemic is prognosticated to continue (2). An estimated 9.5 million acres have been affected, primarily in the Appalachian Mountains, from VA southwards, alone, and an estimated 50% of all dogwoods in PA have been killed. Since acid deposition has been linked experimentally with disease induction, and since the disease incidence and severity are more pronounced at higher elevations where lower pH precipitation events occur, we investigated the effect of acidic foliar sprays on moiphologic changes in the foliar cuticle and trichomes (3), the initial sites of infection and foci of Discula sporulation.
Correlative SEM, freeze-fracture, and laser scanning microscopy ofTilletia controversa teliosporesheath morphology
Authors: Rowe Kimberly A. , Gardner John S. , Hess W.M.
Published: June 2020

The bunts of wheat are infected byTilletiawhich have teliospores with complex multilayered walls. The outer layer or sheath ofTilletiacontroversa teliospores is difficult to characterize unless it is hydrated. The morphology of the sheath has been characterized with freeze-fracture, thin sectioninging and SEM studies. By using specialized, time-consuming thin-sectioning specimen preparation procedures the sheath can be a factor in distinguishingT. cariesandT. controversateliospores. Distinguishing the species is important for marketing wheat. The purpose of these investigations was to develop better methods to characterize the sheath which will help to distinguish teliospores of these two species and races ofTilletiamuch more easily and quickly.
Plants in response to copper toxicity
Authors: Tsay Ching-Chiann , Huang Yu-Fen , Wang Li-Wen , Chen Yung-Reui
Published: June 2020

Plant response to heavy metal in soil varies with plant species, their developmental stages and the ways of pollution. Plants seedlings studied by morphological and biochemical markers through hydroponic culture can provide a way for screening Cu-tolerant plants which are potential plants for removing copper from Cupolluted soil.

Seeds of tested plants obtained from both commercial sources and open field of Cu-polluted regions were germinated in petri dishes. Ten-day-old seedlings were transferred to a Hoagland's solution containing different concentrations of copper. Tested plants with symptoms of copper toxicity were collected as the materials for microscopic observations with OM and TEM, and for isozyme analysis with PAGE electrophoresis.
Intramembrane particles distribution in the naturally synchronous stage of Physarum polycephalum
Authors: Taylor Randolph , Turner Henrie
Published: June 2020

Comparative ultrastructural investigations of the Physarum polycephalum intramembrane particles in the plasma membrane at different stages of the cycle has provided valuable information in relation to possible changes that occur in the plasma membrane of higher organisms. In addition, it gives insight on how plasma membrane changes correlate with gene expression and gene regulation in eukaryotes. In this report Freeze-fracture-etched techniques were utilized to study the arrangements of intramembrane particles (IMP) distribution and density at eight hours of the naturally synchronous plasmodial stage.
Bacterial biofilm behavior in water-supply lines of dental units
Authors: Tall B.D. , George K.S. , Gray R. T. , Williams H.N.
Published: June 2020

Studies of bacterial behavior in many environments have shown that most organisms attach to surfaces, forming communities of microcolonies called biofilms. In contaminated medical devices, biofilms may serve both as reservoirs and as inocula for the initiation of infections. Recently, there has been much concern about the potential of dental units to transmit infections. Because the mechanisms of biofilm formation are ill-defined, we investigated the behavior and formation of a biofilm associated with tubing leading to the water syringe of a dental unit over a period of 1 month.
Ultrastructural analysis of unique glycoconjugates in the rat olfactory system
Authors: Crandall James E. , Hassinger Linda C. , Schwarting Gerald A.
Published: June 2020

Cell surface glycoconjugates are considered to play important roles in cell-cell interactions in the developing central nervous system. We have previously described a group of monoclonal antibodies that recognize defined carbohydrate epitopes and reveal unique temporal and spatial patterns of immunoreactivity in the developing main and accessory olfactory systems in rats. Antibody CC2 reacts with complex α-galactosyl and α-fucosyl glycoproteins and glycolipids. Antibody CC1 reacts with terminal N-acetyl galactosamine residues of globoside-like glycolipids. Antibody 1B2 reacts with β-galactosyl glycolipids and glycoproteins. Our light microscopic data suggest that these antigens may be located on the surfaces of axons of the vomeronasal and olfactory nerves as well as on some of their target neurons in the main and accessory olfactory bulbs.
Neutrophil migration through in vitro interstitial matrix
Authors: Roemer J. , Simon S.R.
Published: June 2020

We are developing an in vitro interstitial extracellular matrix (ECM) system for study of inflammatory cell migration. Falcon brand Cyclopore membrane inserts of various pore sizes are used as a support substrate for production of ECM by R22 rat aortic smooth muscle cells. Under specific culture conditions these cells produce a highly insoluble matrix consisting of typical interstitial ECM components, i.e.: types I and III collagen, elastin, proteoglycans and fibronectin.
Microscopic study of the room temperature deformation mechanisms in β+γ' – (70 at.% Ni −30 at.% Al) in situ composite
Authors: Misra A. , Gibala R.
Published: June 2020

Ductile phase reinforcement is an attractive approach for enhancing the room temperature ductility and toughness of brittle intermetallics such as β−NiAl. For example, a directionally solidified alloy of nominal composition 70 at.% Ni −30 at.% Al, having a two-phase β (brittle matrix) and γ (ductile second phase) microstructure, exhibits up to 9% tensile ductility at room temperature [1]. In the present investigation, a microscopic study has been made to understand the mechanisms involved in the ductility enhancement of the β + γ composite.
3-D examination of the cytoskeletal sheets of mammalian eggs
Authors: Larabell Carolyn A. , Capco David G. , Gallicano G. Ian , McGaughey Robert W. , Dierksen Karsten , Downing Kenneth H.
Published: June 2020

Mammalian eggs and embryos contain an elaborate cytoskeletal network of “sheets” which are distributed throughout the entire cell cytoplasm. Cytoskeletal sheets are long, planar structures unlike the cytoskeletal networks typical of somatic cells (actin filaments, microtubules, and intermediate filaments), which are filamentous. These sheets are not found in mammalian somatic cells nor are they found in nonmammalian eggs or embryos. Evidence that they are, indeed, cytoskeletal in nature is derived from studies demonstrating that 1) the sheets are retained in the detergent-resistant cytoskeleton fraction; 2) there are no associated membranes (determined by freeze-fracture); and 3) the sheets dissociate into filaments at the blastocyst stage of embryogenesis. Embedment-free sections of hamster eggs viewed at 60 kV show sheets running across the egg cytoplasm (Fig. 1). Although this approach provides excellent global views of the sheets and their reorganization during development, the mechanism of image formation for embedment-free sections does not permit evaluation of the sheets at high resolution.
The bone-dental implant interface: HVEM and TEM observations
Authors: Steflik D.E. , Berkery D.J. , Parr G.R. , Sisk A.L. , Hanes P.J. , Lake F.T. , Singh B.B. , Brewer P.
Published: June 2020

Previous studies have suggested the prerequisite of bone interfacing successful endosteal dental implants. This is the concept of osseointegration of dental implants within the jaw. However, the morphology of the actual bone interface on the ultrastructural level is lacking. This current study attempts to elucidate, with correlative high voltage electron microscopy (HVEM) and conventional electron microscopy (TEM), the morphology of the bone-dental implant interface.
Kinetic study of mitochondria in erythropoiesis of anemized amphibians, applying rhodamine 123, flow cytometry and in situ detection of oxidation-reduction enzymes
Authors: Cianciarullo Aurora Marques , Bertho Álvaro Luiz , de Nazareth Maria , de Meirellesu Leal
Published: June 2020

Amphibians erythropoiesis is similar to that of vertebrates in general, comprising: (1) an erythropoietin hormonal stimulation, for differentiation, (2) a lineage of pre cursor maturing cells, (3) alfa and beta globin chains synthesis, (4) an adequate iron supply for heme synthesis, followed by (5) the final hemoglobin (Hb) biosynthesis. Several studies try to establish a correlation between mitochondria and heme synthesis, and the final Hb biosynthesis.
Limits for high-resolution electron microscopy of inorganic materials?
Authors: Smith David J.
Published: June 2020

The era of atomic-resolution electron microscopy has finally arrived. In virtually all inorganic materials, including oxides, metals, semiconductors and ceramics, it is possible to image individual atomic columns in low-index zone-axis projections. A whole host of important materials’ problems involving defects and departures from nonstoichiometry on the atomic scale are waiting to be tackled by the new generation of intermediate voltage (300-400keV) electron microscopes. In this review, some existing problems and limitations associated with imaging inorganic materials are briefly discussed. The more immediate problems encountered with organic and biological materials are considered elsewhere.

Microscope resolution. It is less than a decade since the state-of-the-art, commercially available TEM was a 200kV instrument with a spherical aberration coefficient of 1.2mm, and an interpretable resolution limit (ie. first zero crossover of the contrast transfer function) of 2.5A.
Microtwinning Evidence For The Apparent Five-Fold Symmetry in T2(Al6Li3Cu)
Authors: Vecchio Kenneth S. , Williams David B.
Published: June 2020

Since the discovery in 1984 by Shechtman et al. of crystals which display apparent five-fold symmetry, extensive effort has been given to establishing a theoretical basis for the existence of icosahedral phases (eg.2.). Several other investigations have been centered on explaining these observations based on twinning of cubic crystals (eg.3.). Recently, the existence of a stable, equilibrium phase T2Al6 Li3Cu) possessing an icosahedral structure has been reported in the Al-Li-Cu system(4-6).

In the present study an Al-2.6wt.%Li-l.5wt.%Cu-0.lwt.%Zr alloy was heat treated at 300°C for 100hrs. to produce large T2 precipitates. Convergent Beam Electron Diffraction (CBED) patterns were obtained from two-fold, three-fold, and apparent five-fold axes of T2 particles. Figure 1 shows the five-fold symmetric zero layer CBED pattern obtained from T2 particles.
The energy dependence of axial coherent bremsstrahlung in the high-voltage electron microscope
Authors: Butler J.H. , Spence J.C.H. , Humphreys C.J. , Johnson E.A.
Published: June 2020

Coherent bremsstrahlung (CB) emitted by 200 to 1000 keV electrons traversing oriented silicon crystal targets has been detected using a high voltage electron microscope equipped with an energy dispersive x-ray spectrometer. In this energy range there 1s a strong dependence on the relativistic properties of the Incident electrons: β = v/c varies from about 0.69 (E = 200 keV) to 0.94 (E = 1 MeV); whereas in higher energy accelerator CB experiments β remains close to unity and the variation of any particular peak energy with respect to E is small.

This work concentrates on the detection of the “type B” CB which arises from “juddering” of the electron beam as it traverses successive planes of atoms and is prominent 1n directions transverse to the beam. These spectra exhibit harmonics, peak energies which are Integral multiples of a basic value, which can be ascribed to Umklapp processes in successively higher order Laue zones (H0LZ) of the reciprocal lattice.
Electron spectroscopic imaging of nucleic acid in nucleoprotein complexes
Authors: Locklear L. , Bazett-Jones D.P. , Rattner J.B.
Published: June 2020

The morphological and analytical characterization of chromatin and other nucleo-protein complexes has only been partially successful because of the limitations of normal transmission electron microscopy (TEM). These limitations include the inability to distinguish between the nucleic acid and protein moieties of nucleoprotein complexes and the obligatory use of heavy metal fixatives and stains which can obscure high resolution structure. The high contrast that can be obtained with electron spectroscopic imaging (ESI), a microanalytical technique, circumvents one limitation of ordinary TEM by eliminating the requirement for staining. The most advantageous feature of ESI though is its ability to map the distribution of a specific chemical element within a larger structure. For example, by determining the distribution of phosphorous in a nucleoprotein complex the nature of the organization of the nucleic acid will be revealed.
Valence shell excitations in silicon compounds using ELS
Authors: Skiff W.M. , Carpenter R.W. , Lin S.H.
Published: June 2020

Variations in the valence-shell excitation cross section, as a function of energy loss, across the series of silicon compounds, Si, SiC, Si3N4, and SiO2, were studied using electron energy loss spectroscopy. These variations can be explained in terms of elemental and chemical effects.

Each spectrum was collected using a 100keV beam, a 10mrad collection half-angle, and a 5mrad beam divergence, at 0.7eV resolution, in a Philips 400 FEG, with the thin specimen in kinematic diffracting conditions. The background-stripped Si L edge was fitted to a calculated Si L atomic ionization cross section, hence normalizing the spectrum to cross section per Si atom. The spectrum was finally converted to that per valence electron by using the stoichiometry and the number of valence electrons per formula unit.