bluuebunny/crossref_metadata_2025 huggingface dataset:
Use of Electron Microscopy in Plant Pathology: Abiotic Diseases
Authors: Krause C. R.
Published: June 2020

To the casual observer it seems that abiotic diseases induced by nonliving or noninfectious agents, generally, have been ignored by plant pathologists in lieu of diseases caused by biotic agents (ie. fungi, bacteria, nematodes etc.) or viruses. The apparent lack of interest in abiotic disease problems is not entirely by choice nor by design. Inattention to abiotic disease has been fostered by inadequate techniques and methodologies required to study, characterize and quantify exogenous agents and their effects on host plants.

Occasionally plant pathologists have difficulty in defining terms that describe various aspects of disease. In question are terms like healthy, diseased, normal and abnormal, that in the final analysis are concepts to be developed and carefully considered. Webster's Third New International Dictionary defines disease as “impairment of the normal state of the living plant body or of any of its components that interrupts or modifies the performance of the vital function of the organism, being a response to environmental factors, of specific infective agents, to inherent defects of the organism, or to combinations of these factors”. In essence, environmental factors produce environmental stress that, in turn, induce abiotic disease.
The Internal Structure of Coir (Coconut) Fiber
Authors: Barish Leo
Published: June 2020

The source of commercial coir fiber (actually, a vascular strand) is the massive fibrous husk (3-5 cm thick) surrounding the coconut. This paper reports a SEM study of some aspects of this interesting fiber. The specimens were sputter coated with Au Pd and observed with 4 KV accelerating voltage.

A cut cross section of a retted coir fiber is seen in Figures 1 and 2. A high degree of porosity is apparent; a core of the vascular or conductive bundle is seen surrounded by a large area of elongated sclerenchymatous cells which are cemented together into a composite with pectins or hemicelluloses.

The sclerenchymatous cells may be separated by a maceration process, in this work a dilute solution of sodium hypochlorite. A bent, partially macerated coir fiber showing the configuration and orientation of the cells is given in Figure 3. A completely separated cell showing its general shape and pits is shown in a light photomicrograph in Figure 4.
The Influence of Suture Tautness on Wound Healing
Authors: Stone I.K. , von Fraunhofer J.A. , Masterson B.J. , Apkarian R.P.
Published: June 2020

Wound closure by suturing is necessary to achieve continuity of epithelial covering, to prevent infection and to obviate loss of tissue fluids at the surgical site as well as being necessary in a variety of anastomoses and other procedures. The selection of sutures and the knotting regimen are central to this and these factors have been studied in depth by this group and others. An important aspect of suturing, however, is the tautness or tissue apposition force applied during wound closure although this has been largely neglected in the literature.

The abdominal fascial muscle of rats was sutured by 00-gauge polydioxanone in a loose and a tight apposition mode. Tight closure was the normal suturing force applied by an experienced surgeon while loose wound apposition was achieved by inserting a 3mm dia. rod within the suture loop prior to securing the first throw and then removing the rod after wound closure was complete. After healing for 7 days, tissue at the wound site was sampled for tensile testing and for microscopic examination.
Leiomyosarcoma of Small Vein From Forearm
Authors: Sun C.N. , Schaefer R. , White H.J.
Published: June 2020

Although some 120 cases of leiomyosarcomas of large arteries and veins have been reported since the original case cited by Perl in 1981, with an additional 30 cases of smooth muscle tumors from major veins reported in 1960, it is an unusual event to find malignant smooth muscle tumors arising from the walls of smaller vessels. This report concerns a rather rare type of leiomyosarcoma involving the veins of the upper extremity, having its origin in the antecubital vein in the forearm of a 65 year old white male. The tumor was 2 cm in diameter and pearly white, smooth and somewhat lobulated in configuration. The tumor cells are moderately enlarged and flattened occurring in groups. Cells are arranged in various patterns and whorls. Mitotic figures are frequently observed.
Analysis of the Structure of Paired Helical Filaments
Authors: Crowther R.A. , Wischik C.M. , Stewart M.
Published: June 2020

The neurofibrillary tangles that occur in the brain in senile dementias of the Alzheimer type contain a class of filament with a distinctive morphology, the paired helical filament (PHF). Rather little definitive information is available about the structure or biochemical nature of the PHF. We have recently made a detailed ultrastructural analysis of PHFs. We will summarise here the results of that study, as the findings have an important bearing on the interpretation of the image reconstructions presented below.

PHF enriched fractions were prepared from brains obtained post-mortem from cases with a clinical diagnosis of senile dementia of the Alzheimer type, confirmed histologically by the presence of large numbers of plaques and tangles in frontal and temporal cortex. The preparative protocol involved a series of differential centrifugations.
The Structure and Function Of Intermediate Filament Networks In Mammalian Cells
Authors: Goldman Robert D. , Goldman Anne , Jones Jonathan , Parysek Linda
Published: June 2020

Intermediate filaments (IF) are major cytoskeletal components found in most mammalian cells. One of the most intriguing properties of IF is their high degree of variability with regard to their structural subunit proteins. This ariability is most evident when one compares the protein composition of IF from different cell types. For example, nerve cell IF (neurofilaments) contain the so-called neurofilament triplet proteins, while different epithelial cells contain two or more of the family of IF proteins called keratins. Indeed other cell types appear to have primarily a single subunit species such as in fibroblasts (vimentin, decamin) and muscle cells (desmin).

In the specific case of the nervous system, there is very little information available on specific functions of neurofilaments, although they are thought to be involved in nerve cell shape formation and maintenance, as well as in axoplasmic transport and flow.
Scanned Probe Microscopy: Past, present, and future
Authors: Fisher Knute A.
Published: June 2020

In the past decade a new family of image-forming devices has been developed, machines that do not use lenses and are collectively called scanned probe microscopes (SPM). The SPM family evolved from the scanning tunneling microscope (STM) developed by Binnig and Rohrer in the early 1980s. The tunneling microscope and subsequent probe microscopes, such as the atomic force microscope (AFM), are based on the precise positioning and scanning of a probe within nanometer distances of a surface. Sub-nanometer precision is accomplished using piezoelectric ceramics that change shape with applied electrical potential allowing probes to be moved laterally with less than 0.1-nm resolution and vertically with less than 0.01-nm resolution. This method of positioning has been routinely used with SPM over the past 10 years, during which time many different probes have been developed. These probes measure signals from a variety of physical phenomena such as electron tunneling, atomic force, electrical conductivity, temperature gradients, light absorption, ion currents, and magnetic properties. A significant difference between SPM and conventional light and electron microscopes is that the probes can operate in a wide range of environments including pressures that range from ultrahigh vacuum to ambient pressure, temperatures that range from liquid helium to hundreds of degrees Kelvin, and physical states that include immersion in hydrophobic liquids such as oil and hydrophilic liquids such biological buffers. The probes are usually scanned in either a constant signal mode or in a constant height mode. Signals are amplified and can be used to control the probe's vertical position. The signal is recorded digitally and displayed on a computer screen and thus can be manipulated by image-processing tools to generate topographic maps of the surface. The references at the end of this article cite several of the major reviews of probe microscopy.
Textured crystallization of germanium telluride
Authors: Libera M.
Published: June 2020

Phase-change optical storage uses a focused laser to locally switch a chalcogenide film between the crystalline and amorphous states. Data bits are stored as amorphous spots in a crystal matrix. They can be erased by laser annealing, but applications require fast crystallization during the erase. The crystallization kinetics are not well understood. A recent study of germanium telluride (GeTe) used time-resolved optical measurements and TEM to show that crystallization in Ge48Te52 films is dominated by the 2-D growth of crystallites in the film plane. Current work relates the complex crystallite morphology to the operative transformation kinetics.
Raised ferrite: Yet another austenite decomposition product in microalloyed steel
Authors: Malis T.F. , Dogan B. , Boyd J.D.
Published: June 2020

In a recent study of microstructural evolution in a Ti-V microalloyed steel it was observed that a significant proportion of the ferrite showed a slower etching response and appeared in relief in secondary electron SEM images. Figure 1 shows 2 examples of this “raised ferrite” constituent. Figure la is a Ti-V microalloyed steel controlled rolled and quenched from above the Ar3, temperature. The ferrite (66%) is a mixture of polygonal ferrite (PF) and raised ferrite (RF). The rest of the microstructure is bainite (22%), pearlite (7%) and martensite-austenite (5%). Figure lb is the same steel rolled and quenched from the 2-phase (α+γ) region, and the microstructure comprises deformed ferrite-DF (62%), raised ferrite (24%) and martensite-austenite (14%). Two-surface SEM examination shows that a raised ferrite grain stands in relief on both surfaces, i.e. there is no orientation dependence. Also, no preferred orientation of the raised ferrite grains were detected in the TEM analysis. It was further determined that the hardness of the raised ferrite (235 ± 10 VPH) is higher than polygonal ferrite (182 ± 3 VPH) or deformed ferrite (204 ± 3 VPH), and that it fractures preferentially at low and ambient temperatures (Fig. 2). The literature contains numerous micrographs similar to Figures 1 and 2 which show raised ferrite, yet the structure and origin of this constituent have not been discussed. It is clearly distinguishable from other ferritic phases, and it can influence the fracture properties of steels by acting as a brittle crack-initiating phase.
Structural effect of the SC-AF transition in BSCYCO system
Authors: Wen Shulin , Song Chenyu , Eades J.A.
Published: June 2020

The transition between the SC (superconductor) and the AF (antiferromagnetic semiconductor) has been investigated in the BSCYCO (Bi2Sr2Ca1-xYxCu2O8+Y) system. During the investigation a tetragonal(T)-orthorhombic(O) structural transformation accompanied by a sharp drop in Tc around at Xc=0.4 has been observed.

Some of previous studies on BSCYCO revealed the transition from the SC to the AF around at x=0.5, and interpreted it as a result of a decreasing hole concentration, We have also studied the SC-AF transition of BSCYCO with analytical data combination from not only Tc measurements, but also X-ray diffraction, electron diffraction and energy dispersive spectroscopy (EDS) results. We found that a structural transformation from the tetragonal(T) to the orthorhombic(O) system would be mainly responsible for the SC-AF transition.
Mirror-hexapole corrector with compact beam splitter for eliminating the chromatic and spherical aberration of low-voltage EMs
Authors: Rose H.
Published: June 2020

To significantly improve the performance of electron microscopes it is necessary to enlarge the usable aperture. At low voltages this requirement can only be met if the chromatic and the spherical aberration are corrected simultaneously. For imaging surfaces with reflected electrons (LEEM) a magnetic deflection system separating the illuminating beam from the image-forming beam must be incorporated in the region above the objective lens. Since the use of an electrostatic mirror for the correction of the chromatic aberration also necessitates such a system, it would be extremely helpful if the beam splitter can be designed in such a way that it also separates the parts of the image-forming beam heading toward and away from the mirror.
Surface reconstructions of (001) cleaved GdBa2Cu3O7-δ
Authors: Zandbergen H.W. , McCartney M.R.
Published: June 2020

Very few electron microscopy papers have been published on the atomic structure of the copper oxide based superconductor surfaces. Zandbergen et al. have reported that the surface of YBa2Cu3O7-δ was such that the terminating layer sequence is bulk-Y-CuO2-BaO-CuO-BaO, whereas the interruption at the grain boundaries is bulk-Y-CuO2-BaO-CuO. Bursill et al. reported that HREM images of the termination at the surface are in good agreement with calculated images with the same layer sequence as observed by Zandbergen et al. but with some oxygen deficiency in the two surface layers. In both studies only one or a few surfaces were studied.
Accurate measurements of mean inner potential of crystal wedges using electron holography
Authors: Gajdardziska-Josifovska M. , McCartney M. R. , Weiss J. K.
Published: June 2020

The phase of an electron wave which has interacted with a material is measured in electron holography experiments with respect to a coherent reference wave which has travelled through vacuum. In non-magnetic electron-transparent materials, and under kinematical diffracting conditions, the phase change (Δφ) of the transmitted electron wave depends only on the thickness (t) and the mean inner potential (Ui) of the material: Δφ = c |Ui| t; c being an energy-dependent constant. This phase change measured from electron holograms has been used previously to determine the mean inner potential of amorphous and polycrystalline films of known thicknesses. Refraction effects in RHEED patterns have also been used to determine the mean inner potential of several crystals with flat surfaces. The reported accuracies in these studies have ranged from 2.5% to 9.5%, although uncertainties in specimen thickness and the unknown effects of surface contamination and/or reconstruction are very likely sources of systematic errors. This paper shows that numerical reconstruction of digital holograms, combined with use of cleaved crystal wedges, enables measurement of the mean inner potential of crystals with enhanced accuracy.
Analysis of solute and precipitate effects in microalloyed medium carbon steels by TEM
Authors: McCormick M.A. , Boyd J.D.
Published: June 2020

Modern microalloyed steels most often utilize the austenite grain refining and precipitation strengthening effects of microalloy precipitates. In addition, effects of these elements as solutes have also been noted, although it is often difficult to determine whether solute or precipitate processes are dominant from mechanical or microstructural data. Extensive work has been done to quantify the mechanisms of grain coarsening, recrystallization, and precipitation for austenite in low carbon, flat rolled products. Presently, work is underway to develop this knowledge for medium carbon, round products with the goal of tailoring the final microstructure by Thermomechanical processing.
The chiral smectic H liquid crystalline structure of a comb-shaped side-chain polymer
Authors: Li L.S. , Stupp S. I.
Published: June 2020

The polymer investigated is a comb-shaped polymer with long oligomeric side chains containing a chiral center. The chiral center contains the strongly dipolar nitrile group bound to the aliphatic spacer between aryl units in a stereo-ordered fashion. The chemical structure of the comb polymer is shown below:
The temperature stability of ligand stabilized gold and bimetallic colloids
Authors: Bovin Jan-Olov
Published: June 2020

Preparation and characterization of new monodispersed clusters and colloids of different metals are important for use in several applications like catalysis, microelectronics and sintering. The atomic structure of ligand stabilized, 18 nm, gold colloid is important, since they can serve as the core in preparation of bimetallic systems. The recent developments in preparative cluster chemistry have made it possible to make 35 nm bimetallic layered colloids of gold-platinum and gold-palladium. If the colloids should be useful as catalysts, it is important to establish their thermal stability and structure at the elevated temperatures where catalytic reactions take place. The first preliminary results from a high temperature study in an electron microscope with a heating stage are presented here.
Platinum nanoclusters in doped glassy carbon: An EM investigation
Authors: Spontak Richard J. , Huston Michael E. , Pocard Nicolas L. , Callstrom Matthew R.
Published: June 2020

Fabrication of materials which possess a fine dispersion of nanoscale metallic clusters (referred to here as nanoclusters) is of both commercial and fundamental importance. The relatively large surface area of these particulates makes them particularly attractive for applications in molecular catalysis and microelectronics. From a more fundamental viewpoint, they collectively represent structural intermediates between single atoms and crystalline solids. Efforts designed to produce metallic nanoclusters systematically on specific surfaces or in bulk media have relied on a variety of techniques, such as metal evaporation and sol-gel processes, just to name two. Recent efforts have shown that thermolysis of platinum-containing carbon precursors results in Pt(0) nanoclusters dispersed within a stable conductive carbon matrix. These doped materials, at only 1 atom% Pt, exhibit voltammetric responses for H+ and O2 similar to those of pure platinum while remaining significantly more stable (presumably due to the rigid matrix). The focus of the present work is to employ transmission electron microscopy (TEM) to correlate the characteristics of these nanoclusters with conditions of preparation.
Microstructure and reactivity of small metal particles: The role of Ce additives
Authors: Schmidt L.D. , Krause K. R. , Schwartz J. M. , Chu X.
Published: June 2020

The evolution of microstructures of 10- to 100-Å diameter particles of Rh and Pt on SiO2 and Al2O3 following treatment in reducing, oxidizing, and reacting conditions have been characterized by TEM. We are able to transfer particles repeatedly between microscope and a reactor furnace so that the structural evolution of single particles can be examined following treatments in gases at atmospheric pressure. We are especially interested in the role of Ce additives on noble metals such as Pt and Rh. These systems are crucial in the automotive catalytic converter, and rare earths can significantly modify catalytic properties in many reactions. In particular, we are concerned with the oxidation state of Ce and its role in formation of mixed oxides with metals or with the support. For this we employ EELS in TEM, a technique uniquely suited to detect chemical shifts with ∼30Å resolution.
In situ TEM of silicon oxidation
Authors: Gibson J. Murray , Ross F.M. , Twesten R.D.
Published: June 2020

Oxidation is an important process in materials science. Silicon oxidation is particularly relevant for electronic device fabrication, but it also provides a model system. We report here the use of in-situ TEM for the examination of the microstructural details of the oxidation process.
Flotation of Athabasca oil sands: Microscopical determination of structure of bituminous froth
Authors: Lam W.W. , Payette C. , Munoz V.A. , Mikula R.J. , Tyerman J.
Published: June 2020

The extraction of bitumen from oil sands involves the flotation process where the initial separation of the oil phase, or the bituminous froth, from the inorganic solids and water occurs. However, the froth obtained has high solids concentration and water, which produces problems in downstream operations. Concurrently, some of the oil reports to the tailings, with economic and environmental impact.

Flotation can be considered to be a physical-chemical separation process which depends on the selective adhesion of air to the desired component (bitumen) in order to separate it from the water and solids. The feed to the flotation process is an oil-in-water emulsion with relatively high solids. At some point in the separation vessel, this emulsion inverts and becomes a water-in-oil emulsion and forms the bituminous froth. Understanding this inversion process will help in maximizing water and mineral matter drainage from the bitumen product, leading to an improvement in bitumen extraction from oil sands. As well, the partitioning of solids can be understood by studying their wettability with the froth and thus determining whether or not these solids report to the tailings, or are carried upward by attachment to air bubbles in the flotation cell.
Phase changes during heat treatment of electrodeposited WO3, MoO3 and V2O5
Authors: Veilleux G. , Guerfi A. , Saint-Jacques R. G. , Dao Lê H.
Published: June 2020

Many transition metal oxides have been studied in the last two decades. By an appropriate chemical or electrical means, ions can be inserted into the structure of these oxides with minimal structural changes. This process known as coloration can easily be reversed. This reversible mechanism is of particular interest in applications such as battery and fuel cell electrodes, chemical sensors, electrochromic displays and catalysts.

In this study, films of three transition metal oxides (WO3, MoO3, V2O5) were prepared by electrodeposition. The morphology and the structure of these films were analyzed by transmission electron microscopy (TEM) in their as-deposited states and after heat treatment in ambient air up to 500°C. Previous measurements made by differential scanning calorimetry (DSC) showed exothermic peaks corresponding to phase changes. The temperature values determined at those peaks were then chosen as specific treatment temperatures.
EELS fine structure analysis of radiation damage of V2O5
Authors: Lin Xiwei , Dravid Vinayak P.
Published: June 2020

The oxides of maximum valence transition metals have been extensively studied in view of their useful physical and chemical properties. Vanadium pentoxide is one such compound which exhibits important catalytic properties, but is sensitive to electron beam irradiation. Vanadium pentoxide has the orthorhombic symmetry and the structure is built from deformed octahedra with a longer and weak V-O bond along the c direction. Consequently, V2O5 is a layered structure with (001) cleavage plane, and the oxygen atoms located at the cleavage plane can be easily lost during the electron beam irradiation. In this paper we present time resolved parallel detection EELS study of radiation damage of V2O5 with a 200 kV cold field emission analytical electron microscope (HF-2000). Samples of V2O3 and VO2 are also analyzed for comparison. The EELS spectra were obtained with a spectrometer dispersion of 0.1 eV per channel in TEM image mode using probe sizes of 20-50 nm. The beam current recorded by a picoammeter connected to the screen was calibrated by the direct measurement with a Faraday cup for the calculation of electron dosage.
Cross-section TEM sample preparation of Ti-6Al-4V/SCS6 (SiC) fiber-reinforced composites
Authors: Moberly Warren J. , Apt Scott
Published: June 2020

Titanium-based metal matrix composites (MMC) and titanium aluminide intermetallic matrix composites (IMC) have been selected for future aerospace structural applications. The mechanical integrity of these composites are dictated by the thermodynamic stability of the fiber / matrix interface and deformation that occurs at the interface. The thermal processing incurred during hot-isostatic-pressing (HIP) results in the formation of intermetallic phases, with detrimental mechanical properties, at the interface. In addition, the thermal processing results in residual stresses due to the mismatch in coefficient of thermal expansion (CTE) between the Ti-based matrix and the SiC fiber. In some cases the thermal stresses are sufficient to cause yielding in the matrix, and/or lead to fatigue from the thermal cycling that will be incurred during application.
TEM sample preparation of transparent polycrystalline alumina: Correlation between optical microscopy and TEM images
Authors: Ostreicher K.J. , Sung C.M.
Published: June 2020

Since the discovery of the Lucalox process, a considerable amount of research effort has been devoted to locating both impurities and additives in transparent polycrystalline alumina (PCA). The control of grain growth and porosity by introducing dopants such as MgO and Y2O3 has been shown to directly affect the strength and transmittance properties of the material. The presence of impurities or dopants in excess of their solubility limits leads to precipitation in the bulk and along grain boundaries. It is essential that TEM sample preparation be controlled so as not to introduce damage or pull-out of sec materials it becomes a good method to obtain information concerning grain size and shape, grain orientation relationships, and porosity. The purpose of this study is to describe such a sample preparation process and demonstrate its usefulness in allowing effective correlation of optical microscopy and TEM results.
Mounting of specimens for SEM with the common glue gun
Authors: Barish Leo
Published: June 2020

Specimens are usually attached to SEM studs by means of either sticky tape, adhesives, or melts. The use of sticky tape is very convenient and fast; unfortunately, the bonds formed are not strong or stable. In addition, it is difficult to attach large, irregular shaped specimens with tape. Adhesives, usually solvent–based, can form strong bonds; however, for the satisfactory operation of the coater and the SEM, the solvent must be evaporated completely which can take considerable time.

Melt adhesives can set up strong bonds very quickly and there is available a commercial melt adhesive mounting kit; however, the procedure for its use is cumbersome. When using this kit, the adhesive is first melted onto thin aluminum plates, which are then cooled and placed aside. When ready for the attachment of the specimen, a plate is heated to remelt or soften the adhesive; the specimen is then adhered to the surface. After cooling, the plate with the attached specimen is clamped onto a special SEM stud.
Electron crystallography of membrane phospholipids
Authors: Dorset Douglas L.
Published: June 2020

Membrane phospholipids are notoriously difficult to crystallize to sample sizes suitable for collection of single crystal X-ray intensity data, accounting for the relatively few crystal structures which have been reported to date. At the 24th Annual EMSA meeting, Parsons and Nyburg suggested that the enhanced scattering of electrons by matter be exploited to obtain single crystal electron diffraction patterns from the more readily available microcrystalline preparations, an example of which was shown in a subsequent paper. For almost 20 years ve have investigated the utility of such intensity data forab initiocrystal structure analysis.
Helical polymers of the REV protein of human immunodeficiency virus 1
Authors: Misra Manoj , Trus Benes L. , Wingfield Paul , Steven Alasdair C.
Published: June 2020

The pattern of viral gene expression in cells infected with HIV-1 is orchestrated by several regulatory proteins. One such viral gene product is Rev (regulator of expression of virus), a 13 kDa basic protein that plays a crucial role in determining whether full-length transcripts coding for the major structural proteins of HIV-1 are exported intact from the nucleus into the cytoplasm, so that active proliferation of the virus can ensue. Purified Rov has been shown to polymerize in vitro into long filamentous polymers. Based on this and other observations, it has been hypothesized that Rev functions rather like the nucleocapsid protein of a filamentous RNA virus, and that coating of the transcripts in question by Rev is the mechanism whereby they are protected from splicing. To explore this hypothesis further, we have studied the structure of these Rev polymers in greater detail.
Variations in signal-mediated transport through the nuclear pores as a function of cellular activity
Authors: Feldherr C.M. , Akin D.
Published: June 2020

Previously, we utilized colloidal gold particles coated with nucleoplasmin, which contains well characterized nuclear localization signals (NLS), to study signal-mediated nuclear transport in proliferating and quiescent BALB/c 3T3 cells. The particles were injected into the cytoplasm, and nuclear uptake (N/C gold ratios) was later determined by TEM. The functional size of the transport channels was also analyzed by measuring the particles that entered the nucleoplasm. When large gold particles (110 to 270 Åin diameter) were injected, nuclear uptake was significantly greater in proliferating as compared to quiescent cells. The average fonctional pore diameter was approximately 230 Å during proliferation, and 140 Åor less in quiescent populations.
Correlative light and electron microscopy of primary (9+0) cilia: Response of ciliary varicosities to hypotonic treatment in kidney epithelial cells
Authors: Bowser Samuel S. , Roth Karen E. , Rieder Conly L.
Published: June 2020

Primary cilia are centrosomal appendages which in kidney epithelia extend several micrometers from the apical cell surface into the lumen of the kidney tubule. Although considered by some to be “rudimentary appendages” because they are nonmotile, their intimate structural association with the Golgi apparatus and nucleus suggests to others that they mediate interactions between the cell and its environment. Such a sensory role is not without precedence since various photo- and chemoreceptors are highly modified primary cilia. Despite the near-ubiquitous distribution of primary cilia few studies have addressed their function experimentally, and little detailed information is available regarding their behaviorin vivo.
The dynamics of lipoprotein binding and endocytosis in macrophages: A correlative ultrastructural and light microscopic approach
Authors: Jones Nancy L. , Landers Stephen C. , Allen Nina S. , Lewis Jon C.
Published: June 2020

The dynamics of lipoprotein binding and endosome formation on pigeon monocyte-derived macrophages have been studied using Allen video-enhanced contrast, differential interference-contrast microscopy (AVEC-DIC) and nanovid (video-enhanced brightfield) microscopy. Subsequent to video-microscopy the ultrastructural (3-D) organization was examined by correlative Intermediate Voltage Electron Microscopy (IVEM). The use of gold “finder” grids mounted on glass coverslips provided the mechanism by which cells after being observed in the video system were located in the electron microscope. The lipoprotein, beta migrating low density lipoprotein (βVLDL), was conjugated to gold colloids (15-40 nm) to enhance visibility in both video-microscopy and IVEM. Subsequent to video microscopy, the cells were fixed with glutaraldehyde, dehydrated through ethanol and dried from CO2 by the critical point method for whole-mount EM. Such a correlative approach allowed static ultrastructural features to be associated with cellular dynamics as observed and recorded by video.
Three-dimensional organization and functional relationships of endocytotic compartments in pig intestinal epithelial cells
Authors: Heath Julian P. , Nichols Buford L. , Kömüves László G.
Published: June 2020

The newborn pig intestine is adapted for the rapid and efficient absorption of nutrients from colostrum. In enterocytes, colostral proteins are taken up into an apical endocytotic complex of channels that transports them to target organelles or to the basal surface for release into the circulation. The apical endocytotic complex of tubules and vesicles clearly is a major intersection in the routes taken by vesicles trafficking to and from the Golgi, lysosomes, and the apical and basolateral cell surfaces.

Jejunal tissues were taken from piglets suckled for up to 6 hours and prepared for electron microscopy and immunocytochemistry as previously described.
Three-dimensional reconstruction by HVEM tomography
Authors: McEwen Bruce F. , Frank Joachim
Published: June 2020

Electron Tomography has recently emerged as an effective tool for three-dimensional (3D) ultrastructural analysis, particularly when combined with Intermediate or High Voltage Electron Microscopy (IVEM and HVEM) (reviewed in 1-3). In this approach a tilt series is recorded over a large angular range, up to 180°, typically with an angular interval of 2-5°. The individual images are digitized, rotationally and translationally aligned, the image density normalized, and finally the 3D reconstruction computed. After low pass filtration to the limiting resolution, the reconstruction volume can be examined by a growing number of computer graphic tools. The chief advantages of tomography are that: 1) the reconstruction is an objectively determined, uninterrupted 3D density map of the specimen, as seen in the electron microscope; and 2) the method is generally applicable to any sample which is sufficiently contrasted or isolated from its surrounding environment.
Spatial and temporal expression of fibronecttns and integrins duringXenopusdevelopment
Authors: DeSimone Douglas W. , Dalton M. Susan , Hens Mark D. , Hill Bethanne , Ramos Joe W. , Ransom David G. , Whittaker Charles A.
Published: June 2020

A central challenge in biology is to understand the cellular processes that direct morphogenesis and the formation of the basic body plan during development. These events are controlled to large extent, by adhesive interactions of cells with one another and with their extracellular environments. Specifically, we are investigating the structure, function and expression of two groups of molecules thought to play important roles in promoting cell adhesion and migration in the embryo: fibronectins (FNs), which are large extracellular matrix (ECM) glycoproteins with many adhesion related functions; and integrins, which are the cellular transmembrane-receptors for FNs and several other components of the ECM.
EM as an important diagnostic tool in neuronal ceroid-lipofuscinosis (NCL, Batten's disease)
Authors: Muss Wolfgang H. , Puttinger Rudolf , Thurner Josef
Published: June 2020

Neuronal Ceroid-Lipofuscinoses (NCL) are a group of neurometabolic/neurodegenerative disorders characterized by an accumulation of metabolites (autofluorescent “1ipopigments-Ceroid-Lipofuscin”) in central and peripheral nerve system as well as in retina, skeletal muscle, fibroblasts, histiocytes and other body organs. Batten's Disease (syn:SPIELMEYER-VOGT Disease; iuvenile onset NCL) presents with an autosomal recessive inheritance (1). Immunochemical studies (2) suggest that subunit c of mitochondrial ATP-Synthase is stored in the late infantile, iuvenile and adult forms of NCL ; chromosome studies indicate Batten's Disease maps to human chromosome 16 (3); erythrocyte and platelet phospholipids and fatty acids have been reported to be decreased (4), also concentrations of phosphorylated dolichol are reported to be 10 to 20-fold higher in brain from NCL than age-matched controls (5). Intracel1ular/lysosomal storage products histologically are PAS-positive, extractable and, ultrastructurally, the inclusions/accumulation products display characteristic recti-and curvilinear profiles as well as fingerprint bodies (for histological / ultrastructural classification criteria cf. (6)).
Correlative light and transmission electron microscopy of tubular aggregates in skeletal muscle
Authors: Manfredi Thomas G. , Ding Wenjing , Bronson Roderick
Published: June 2020

Tubular aggregates (TAs) have been identified with a number of myopathies in humans. Periodic paralysis and muscle pain are frequently associated with TAs. Very little is known about the functional and anatomical significance of TAs in myopathic and aging human muscle. Recently, animal models for TAs have been identified which suggested that TAs are gender specific. However, recent studies suggest a need for more controls.
Effects of ryanodine and caffeine on subcellular elemental distributions in relaxed and tetanized rat papillary muscles
Authors: Hurley B.J. , Cantino M.E. , Johnson D.E.
Published: June 2020

Regulation of intracellular free calcium is crucial to the process of contraction in cardiac muscle. Many inotropic agents are thought to exert their effects by way of changes in the levels of myoplasmic free Ca2+. While the effects of caffeine and ryanodine on myocardial contractility share some similarities, their pharmacological properties appear to be quite different. Although both agents affect Ca sequestration by the sarcoplasmic reticulum, ryanodine appears to act specifically on the Ca release channels of the jSR, while caffeine may affect transsarcolemmal calcium transport and calcium sensitivity of the myofilaments as well. To date, several investigators have applied electron probe X-ray microanalysis (EPXMA) to study effects of one or the other of these agents on subcellular elemental distributions, however, none have compared them in the same system. We have used EPXMA to compare suteellular elemental concentrations in rat papillary muscle in the presence of caffeine and ryanodine, in relaxed and tetanized conditions.
Ultrastructure and immunogold labeling of cytoplasmic fibrous bundles in tobacco leaf cells infected with tobacco vein mottling virus
Authors: Ammar E. D. , Thombury D. W. , Pirone T. P.
Published: June 2020

Tobacco vein mottling virus (TVMV) is a potyvirus, with flexuous filamentous particles ca. 765 nm long and 12-13 nm in diameter. TVMV is transmitted by sap inoculation and by aphid vectors. Cylindrical inclusions characteristic of infections with potyviruses have been found in the cytoplasm of TVMV-infected tobacco leaves and protoplasts, and the presence of fibrous inclusions of unknown composition in the cytoplasm and nuclei of TVMV-infected tobacco has been reported. Here, we report the results of transmission electron microscopy (TEM) and immunogold labeling of cytoplasmic fibrous bundles found in TVMV-infected leaf cells, providing evidence that these bundles are composed of TVMV virions and/or coat protein.
Ultrastructural study of uptake of monastral blue by the pulmonary intravascular macrophages of sheep in the presence and absence of surface coat
Authors: Singh B. , Jassal D. S. , Atwal O. S. , Minhas K.
Published: June 2020

Pulmonary intravascular macrophage (PIM) is an important mononuclear phagocyte of some animal species. In sheep these cells are actively involved in the clearance of microbes and endotoxins. By treating the tissue with tannic acid we have identified at the ultrastructural level a unique globular surface coat, arranged at a distance of 30-40 nm from the cell periphery, This coat is hypothesized to be lipoprotein in nature as tannic acid complexes with the globules to enhance their electron density. This surface coat is highly sensitive to in vitro lipolytic lipase digestion and in vivo heparin treatment.
In situmetal mirror cryofixation of rat kidney for electron probe x-ray microanalysis
Authors: Freudenrich Craig C. , Hockett Daniel , Winter Kerri , Ingram Peter , LeFurgey Ann
Published: June 2020

Many studies of proximal tubule function require information about the elemental composition in subcellular compartments that can be obtained by electron probe x-ray microanalysis (EPXMA). While experiments of this type have been performed on isolated proximal tubule preparations, it is also necessary to conduct parallel experiments on intact tissue to verify those results obtained with isolated tubules. One limitation in conducting EPXMA analysis on whole tissue is obtaining adequately cryopreserved tissue. Metal mirror cryofixation techniques have yielded excellent preservation in dissected tissues or cell cultures. Therefore, experiments were performed to assess the efficacy ofin situmetal minor fixation of the intact rat kidney.
Snapshot blotting: The transfer of nucleic acids and nucleoprotein complexes from electrophoresis gels to EM grids
Authors: Jett Stephen D.
Published: June 2020

The electrophoresis gel mobility shift assay is a popular method for the study of protein-nucleic acid interactions. The binding of proteins to DNA is characterized by a reduction in the electrophoretic mobility of the nucleic acid. Binding affinity, stoichiometry, and kinetics can be obtained from such assays; however, it is often desirable to image the various species in the gel bands using TEM. Present methods for isolation of nucleoproteins from gel bands are inefficient and often destroy the native structure of the complexes. We have developed a technique, called “snapshot blotting,” by which nucleic acids and nucleoprotein complexes in electrophoresis gels can be electrophoretically transferred directly onto carbon-coated grids for TEM imaging.
Detection of cyclosporin A and its cytosolic binding protein, cyclophilin, in CYC A high-producing strain of Tolypocladium terricola
Authors: Matha Vladimír , Jegorov Alexander , Weyda Frantíšek
Published: June 2020

Cyclosporin A (Cyc A), a cyclic fungal undecapeptide produced by various deuteromyces is a potent immunosuppressant widely used in human medicine to prevent rejection of transplanted organs such a kidney, liver, heart and bone marrow. Although originally isolated as an antifungal compound, practically no attention was devoted to its effect on the physiology of its high-producing organisms. In vertebrate cells, the cytosolic Cyc-A binding protein, cyclophilin, is expected to be a primary target involved in the regulation of Cyc A immunosuppressive effect. Similarly, the direct cyclophilin-mediated effect (toxicity) confirming the key role of this Cyc A receptor in Cyc A function, was determined even in Neurospora crassa and Saccharomyces cerevisiae. Induction of Cyc A resistance in both microorganisms was characterized by either of the complete lost of cyclophilin or by the lost of its ability to bind Cyc A.
Lobular patterns of the immunocytochemical localization of enzymes involved in hepatic carbohydrate metabolism
Authors: Giffin Bruce F. , Morris Randal E. , Drake Richard L. , Cardell Robert R.
Published: June 2020

A heterogeneous distribution of many of the enzymes involved in carbohydrate metabolism has been demonstrated within the lobules of the liver. Biochemical studies have demonstrated that hepatocytes in the periportal zone exhibit higher activities of gluconeogenic enzymes, whereas higher activities of glycolytic enzymes are found in cells surrounding the central vein (pericentral). These studies were undertaken to determine the lobular distribution of phosphoenolpyruvate carboxykinase (PEPCK), glycogen synthase (GS) and glycogen phosphorylase (GP) in fed and fasted rats with an immunocytochemical technique using a gold conjugated secondary antibody.
Scanning electron microscopy of erythrophagocytosis by Entamoeba histolytica trophozoites
Authors: Tsutsumi Victor , Martinez-Palomo Adolfo , Tanikawa Kyuichi
Published: June 2020

The protozoan parasite Entamoeba histolytica is the causative agent of amebiasis in man. The trophozoite or motile form is a highly dynamic and pleomorphic cell with a great capacity to destroy tissues. Moreover, the parasite has the singular ability to phagocytize a variety of different live or death cells. Phagocytosis of red blood cells by E. histolytica trophozoites is a complex phenomenon related with amebic pathogenicity and nutrition.
Banded aggregates containing fibrillin are present in the cartilage matrix adjacent to chondrocytes in individuals affected with scoliosis
Authors: Keene Douglas R. , Fairhurst Magaret , Ridgway Catherine C. , Sakai Lynn Y.
Published: June 2020

Matrix microfibrils are present in the connective tissue matrices of all tissues. Following standard TEM processing, they appear in cross section as cylindrical fibrils 8-10 nm in diameter, often associated with amorphous elastin. They are also seen in the absence of amorphous elastin, for example in the shallow papillary layer of skin, and also in cartilage matrix (Figure 1). Negative stain and rotary shadowing studies suggest that microfibrils are composed of laterally associated globular structures connected by fine filamentous strands (“ beaded strings”), and that they are extendable. Immunoelectron microscopy has demonstrated that fibrillin, a 350 Kd glycoprotein, is distributed along all microfibrils with a relaxed periodicity of about 54 nm The gene coding for fibrillin has recently been identified and is defective in the Marfan syndrome.
3-D analysis of spindle structure in the yeast,Schizosaccharomyces pombe(S. pombe)
Authors: Ding Rubai
Published: June 2020

Mitosis in yeast is currently the subject of many genetic and molecular biological studies, but structural work on yeast mitosis has been comparatively limited due in part to the difficulty of obtaining well preserved samples. A structural study of yeast spindles is important because yeast are unicellular, eukaryotic organisms that may provide a simple model of mitosis.S. pombewas chosen because much is known about its molecular biology, and there are several mutants that affect its mitosis. Here we describe a method for obtaining well preserved samples ofS. pombeduring mitosis using high pressure freezing. This method has been used together with EM of serial sections and computer facilitated reconstruction to build three dimensional (3-D) models of spindle structures.
Preplate neurons in embryonic mouse cortex: Ultrastructural observations using photoconversion of the fluorescent lipophilic dye dil
Authors: Hassinger Linda C. , Crandall James E.
Published: June 2020

We have begun to look directly at small numbers of afferent axons to early generated neurons that form the preplate in the developing mouse cortex. The carbocyanine dye Dil (1’1, dioctadecyl-3,3,3’3’-tetramethyl-indocarbocyanine) has proved especially useful for this goal. DiI labels axons and their terminals with greater sensitivity and without some of the disadvantages of axon filling with HRP. The increased sensitivity provided by labeling embryonic axons with DiI has given us new insights into the development of cortical afferents. For instance, we reported originally that afferents from the thalamus were present below the cortex as early as embryonic day 15 (E15) based on HRP injections into mouse embryos. By using DiI placements into the thalamus in aldehyde-fixed brains, we now know that thalamic fibers reach the cortex 24 hrs earlier.
Nuclear change during differentiation of Entamoeba invadens
Authors: Morales-Vallarta M. , Mata-Cárdenas B. , Ramírez-Bon E.
Published: June 2020

The cyst of Entamoeba histolytica is the infective phase of this parasite, but much of its differentiation process remains unknown since it is not possible its in vitro encystation. However, differentiation of E. invadens, an ameba that parasites reptiles is used as an experimental model for amebiasis research, specially in differentiation aspects, since E. invadens can be induced to in vitro encystation.

The nuclear division during encystation of E. invadens has been described by some authors, but this work, has described this process through light microscopy. In the present work we report the morphologic nuclear change and the chromatin organization observed by electron microscopy.

Trophozoites of E. invadens IP-1 were grown in TP-S-1 medium, and encysted in Rengpien and Bailey medium (AEM). During encystation several samples were analysed for different times. The cysts of trophozoites were washed with phosphate buffer saline, postfixed in 1% osmium tetroxide in 0.2 M phosphate buffer pH 7.2 dehydrated in ethyl alcohol and embedded in epoxi resin.