bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chemoselective cluster labelling of biomolecules
Authors: Foley C. J. , Maelia L. E. , Hainfeld J. F. , Wall J. S. 
Published: June 2020

The Brookhaven STEM is capable of visualizing single heavy atoms at a beam dose of >103 el/Å2. Heteropolytungstate clusters, including W12PO403, have been found to incorporate several desirable properties as labels for biological specimens. They may be resolved at much lower beam doses due to their high concentrations of multiple heavy atoms and are directly visible labels. A lower beam dose also helps to preserve the biological structure of the specimens. Furthermore, they are extremely stable in the electron beam. Lastly, they are capable of being derivatized as chemoselective reagents for specific binding sites on biomolecules, as in the previously reported undecagold compound.Two new classes of heavy atom labels, one specific for sulfhydryl and the other specific for both amino and sulfhydryl binding sites on proteins, have been synthesized by reactions analogous to those illustrated in Scheme 1.
Correlative light and high-voltage electron microscopy of primary (9 + 0) cilia in cultured kidney epithelial cells
Authors: Roth K. E. , Davison E. A. , Myers N. , Rieder C. L. , Bowser S. S. 
Published: June 2020

With few exceptions, a single primary cllium is associated with virtually all vertebrate cell types. These cilia are often located adjacent to the nucleus and possess a 9+0 axonemal microtubule pattern which is generated by the “eldest” or “parent” centriole. Despite their ubiquity, the in vivo properties of primary cilia are largely unknown, primarily because their orientation perpendicular to the dorsal cell surface (and parallel to the optical axis) makes them difficult to observe by LM. To circumvent this problem, we have developed novel methods for imaging primary cilia in vivo and for examining selected cilia at the EM level.Kidney epithelial cells (PtK, MDCK, BSC) are grown to confluency on 22 x 40mm solvent-cast Formvar films (0.5 μm thick). A side view of the mono-layer is obtained by folding the film, cell-side out, and sandwiching it in a simple coverslip chamber.
Anatomy and ultrastructure of Colocasia esculenta (L.) Schott (Araceae)
Authors: Stein B. D. , Strauss M. S. 
Published: June 2020

Taro, Colocasia esculenta (L.) Schott (Araceae), is a staple crop grown in much of the tropics and subtropics. The plant consists of an underground stem, the corm, which is the harvestable portion, and aerial leaves. Most production is by subsistance farmers and the plant is an important part of the culture of these people.Only a few studies have been done on the plant and its anatomy. In addition, much of the previous work on monocot anatomy has been done on the Poaceae. To establish a baseline for non-symptomatic plants for the study of diseases and physiology of taro and to expand the knowledge of the anatomy of monocotyledons, taro was examined ultrastructurally.Leaf tissues for TEM were fixed in glutaraldehyde, postfixed in osmium tetroxide, dehydrated in acetone, infiltrated and embedded in Spurr's epoxy. Blocks were sectioned on a LKB Ultramicrotome III.
Ultrastructure and peroxidase activity of alveolar macrophages in cystic fibrosis
Authors: Garlich D. J. , Clawson C. C. , Elliott G. R. 
Published: June 2020

Alveolar macrophages (AMs) and polymorphonuclear leukocytes (PMNs) are the two host defense cells responsible for bacterial clearance in infected lungs. In cystic fibrosis (CF), with its accompanying pulmonary infection, these cells are unable to rid the lung of invading bacteria. This has raised doubts about CF-AMs’ phagocytic ability and metabolism. Their in vivo morphology has had little attention, but a commonly held belief is that the CF-AM ultrastructure is essentiaIly normal and that these cells have not been phagocytically active. The present morphologic study was undertaken for evidence of ingestion by the CF-AM. Cytochemical staining for myeloperoxidase (MPO) was performed to aid in determining the cause for increased luminol-dependent chemiluminescence by the CF-AM, when stimulated by phorbol myristate acetate.Fiberoptic broncho-alveolar lavage was performed on 12 CF patients and 17 normal healthy volunteers.
Kidney proximal tubules: Ultrastructural response to changes in calcium and adenosine triphosphate
Authors: Craig B. L. , Lefurgey A. , Jacobs W. R. , Mandel L. J. 
Published: June 2020

Use of conventional transmission electron microscopy (TEM) and x-ray microanalysis (EPXMA) to identify the intracellular sites of Ca binding and release has provided valuable Information concerning the mechanism for the cellular action of Ca in a variety of cells. In the kidney much indirect evidence links Ca with cellular Injury, but direct measurements of Ca compartmentation are lacking. We report here our initial ultrastructural observations of kidney proximal tubules exposed to agents which alter the compartmentation of Ca in predictable ways. This TEM evaluation of intracellular structural compartments such as mitochondria or endoplasmic reticulum provides the basis for correlative EPXMA studies of elemental compartmentation under the same conditions.A suspension of kidney proximal tubules was isolated from the rabbit kidney as previously described and incubated at 37°C for up to 20’ with the Ca lonophores A23187 (5μM) or ionomycin (10 μM) or with the mitochondrial uncoupler FCCP (4 μM).
Effects of aging on axon terminals in the dentate molecular layer
Authors: Cullen-Dockstader K. , Fifkova E. 
Published: June 2020

Normal aging results in a pronounced spatial memory deficit associated with a rapid decay of long-term potentiation at the synapses between the perforant path and spines in the medial and distal thirds of the dentate molecular layer (DML), suggesting the alteration of synaptic transmission in the dentate fascia. While the number of dentate granule cells remains unchanged, and there are no obvious pathological changes in these cells associated with increasing age, the density of their axospinous contacts has been shown to decrease. There are indications that the presynaptic element is affected by senescence before the postsynaptic element, yet little attention has been given to the fine structure of the remaining axon terminals. Therefore, we studied the axon terminals of the perforant path in the DML across three age groups.5 Male rats (Fischer 344) of each age group (3, 24 and 30 months), were perfused through the aorta.
Scanning Electron Microscopy of mouse BALB/C/Cd polycystic renal disease
Authors: Keyhani E. , Penasse W. 
Published: June 2020

Mouse BALB/C/Cd exhibited spontaneous transplantable kidney adenocarcinoma which affected both sexes and involved both kidneys. This disease is characterized by plain cysts and cysts with single or multiple polyps to solid tumors at various stages of evolution. The fine structure of solid tumor was previously described.Single or multiple (up to 10) cysts were present throughout the cortex parenchyma. Their sizes ranged from 1 to 8 mm in diameter. The cysts occurred from both proximal and distal tubules and were composed of a single layer of cubic-cylindrical epithelial cells. Most cysts exhibited single or multiple focal areas of epithelial polypoid hyperplasia. Single polyps consisted of accumulations of hyperplasic cells piling up on top of each other (Fig. l). The other form consisted of single or multiple branched polyps with a central vascularized core (Fig. 2). The number of cells forming polyps hyperplasia varied between a dozen to up to several hundreds of cells.
The effects of different fixatives on the porcine integument
Authors: Monteiro-Riviere N. A. , Manning T. O. 
Published: June 2020

The porcine integument is structurally similar to the human integument and is frequently used in dermatological studies. To assess the viability of porcine skin or to study cutaneous toxicity, normal cells and organelles must be optimally preserved with minimum alteration from the living state. Several investigators have proposed different fixation methods to study the integument. However, some of these methods are not appropriate for the porcine species. The objective of this study is to assess different fixatives and osmolalities for the porcine integument.Skin samples were obtained from Yorkshire pigs, minced and placed in one of the following fixatives overnight at 4°C; 1. 2% glutaraldehyde(G) in O.1M phosphate buffer (PB) (397 mOsm), 2. 2% G in 0.2M PB (535mOsm), 3. 4% G in 0.1M PB (566 mOsm), 4. 4% G in 0.2M PB (786 mOsm), 5. 4% formaldehyde and 1% G in PB (1774mOsm), 6. 5% G and 4% paraformaldehyde in 0.2M cacodylate buffer (CB) (1522mOsm), 7. 2.5% G and 2% paraformaldehyde in 0.2M CB (976mOsm).
Ultrastructure of a caffeine-resistant mutant of Aspergillus parasiticus during aflatoxin production
Authors: Jones S. B. , Dobson T. O. , Stahl H. G. , Buchanan R. L. 
Published: June 2020

Caffeine (1,3,7-trimethylxanthine) inhibits growth and aflatoxin synthesis in A. parasiticus. A caffeine-resistant mutant (BCR1) of A. parasiticus NRRL 2999 was isolated in which sporulation and aflatoxin production occurred only in the presence of caffeine. Further, when cultured in glucose-mineral salts (GMS), BCR1 required amino acids in addition to caffeine in order to produce aflatoxin. A system for ultrastructure study was thus available in which aflatoxin synthesis was controlled by supplementation with amino acids. Experiments were conducted to identify morphology that could be correlated with aflatoxin production in the mutant.Cultures were conidia-initiated in GMS at 28C with agitation, with 6% peptone as amino acid source. Caffeine at 4 mg/ml permitted full growth and stimulated maximal aflatoxin accumulation. Fungal pellets were retrieved at 4 days and portions of the periphery were fixed in 3% glutaraldehyde in 80 mM Na-cacodylate, pH 7.0, for 3 hr.
A comparative study of fixation and dehydration techniques for the preservation of conidial structures in fungi for SEM
Authors: Edelmann Richard E. , Hogan Margaret E. 
Published: June 2020

Conventional preparative techniques for biological specimens For scanning electron microscopy (SEM), when used for Fungal specimens, involve immersion in fixation and dehydration solutions. This often results in physical damage to delicate reproductive structures. Attempts at eliminating this damage using OsO4 vapors as a fixative, followed by air drying, may also produce less than optimal results.In order to devise an improved method for preparing fungal specimens, several genera were selected for their very delicate aerial conidial structures, and were prepared using six different procedures. The various protocols were as Follows:1)Immersion Fixation in 1% paraformaldehyde, 2.5% glutaraldehyde in H2O, post-fixation with 2% OsO4, and critical point drying2)2% OsO4 (in H2O) vapor fixation and air drying3)2% OsO4 (in H2O) vapor fixation and freeze drying4)Powdered paraformaldehyde in a 6% relative humidity atmosphere vapor fixation and air drying5)Aqueous 5% paraformaldehyde/8% glutaraldehyde vapor fixation, and air drying6)Aqueous 5% paraFormaldehyde/8% glutaraldehyde vapor fixation, and freeze drying
Adapting cytochemical protocols to localize antigens, labeled-ligands, and labeled probes for mRNA
Authors: Childs Gwen V. , Unabia Geda , Lloyd Jonathan 
Published: June 2020

Current methods available in immunocytochemistry can be adapted to obtain multiple stains for antigens, labeled-ligands, and/or mRNA and thus achieve a wider view of the structural and functional organization of a cell. In this presentation, applications of immunocytochemical stains for pituitary hormones in combination with affinity cytochemical stains for labelled probes for ligand-receptor complexes or messenger RNA will be described along with a practical view of how each stain is quantified.The ABC peroxidase stains are useful for studies of antigens in semi-thin (1 μm) plastic-embedded sections or for antigens, biotinylated ligands or biotinylated probes for mRNA in whole cells. For the first group, cells or tissues are fixed optimally for the antigen and then embedded in plastic with a-protocol adapted to the antigen or antigenic site. Commonly used plastics that avoid harsh dehydrating or curing conditions include Lowicryl or LR White. Epoxy plastics may be used for hardy antigens.
A new high-resolution Electron Energy-Loss Spectroscopy microscope
Authors: Tanaka Michiyoshi , Terauchi Masami , Kuzuo Ryuichi , Tsuno Katsushige , Ohyama Junichi , Harada Yoshiyasu 
Published: June 2020

Boersch, Geiger and coworkers constructed high resolution electron energy-loss spectroscopy (EELS) instruments. These had a very high energy resolution of approximately 3meV, but were operated at a relatively low accelerating voltage of about 30kV and could only obtain spectra from specimen areas greater than about 10µm in diameter.We have been developing a new EELS instrument to investigate detailed electronic structures and thermal vibrations by taking spectra from specified small specimen areas and specified small reciprocal space areas. Our EELS microscope is composed of a thermal-type field emission gun, a Wien-filter monochrometer, the basic part of a JEM-1200EX microscope, a Wien-filter analyzer and a CCD detection system (Fig.1). Figure 2 schematically shows an xy-section of the Wien filter. The filter was designed to produce the Wien condition E=vxB (E:electric field, B:magnetic field, v:velocity of electrons) not only in the filter but also in the fringing field regions and to produce the stigmatic focus. The length of the filter was chosen to be 4cm.
Electron-optical design of a high-resolution objective lens for low-voltage Scanning Electron Microscope of biological applications
Authors: Ximen J. , Lin P. S. D. , Pawley J. B. , Schippert M. 
Published: June 2020

By providing higher image contrast and reduced charging artifacts, the low voltage scanning electron microscope (LVSEM) is a valuable tool for surface characterization, of particular importance on nonconductive material such as biological specimens. Several SEM designs optimized for use at low voltage have been proposed.Recently, we have designed a new high resolution LVSEM using a field emission gun. The key problem is to decrease both the spherical and chromatic aberration coefficients by using a magnetic lens of small bore diameters(5mm and 10mm) and a narrow gap (7.5mm) (FIG. 1). In our first design, the magnetic lens is built around the side-entry stage of a Philips 300kV TEM and performs as well as that in the present Hitachi SEM H-900 or H-900S. Its simple design has been chosen for reliability and flexibility in farbrication.
A new tool for rapid development of electron microscopy negatives and micrographs: Initial impressions of the MOHR/PRO-8 processor
Authors: Long James C. 
Published: June 2020

Over the years, many techniques and products have been developed to reduce the amount of time spent in a darkroom processing electron microscopy negatives and micrographs. One of the latest tools, effective in this effort, is the Mohr/Pro-8 film and rc paper processor.At the time of writing, a unit has been recently installed in the photographic facilities of the Electron Microscopy Center at Texas A&M University. It is being evaluated for use with TEM sheet film, SEM sheet film, 35mm roll film (B&W), and rc paper.Originally designed for use in the phototypesetting industry, this processor has only recently been introduced to the field of electron microscopy.The unit is a tabletop model, approximately 1.5 × 1.5 × 2.0 ft, and uses a roller transport method of processing. It has an adjustable processing time of 2 to 6.5 minutes, dry-to-dry. The installed unit has an extended processing switch, enabling processing times of 8 to 14 minutes to be selected.
Exit-surface wave reconstruction using a focal series
Authors: de Ruijter W.J. , McCartney M.R. , Smith David J. , Weiss J.K. 
Published: June 2020

Further advances in resolution enhancement of transmission electron microscopes can be expected from digital processing of image data recorded with slow-scan CCD cameras. Image recording with these new cameras is essential because of their high sensitivity, extreme linearity and negligible geometric distortion. Furthermore, digital image acquisition allows for on-line processing which yields virtually immediate reconstruction results. At present, the most promising techniques for exit-surface wave reconstruction are electron holography and the recently proposed focal variation method. The latter method is based on image processing applied to a series of images recorded at equally spaced defocus.Exit-surface wave reconstruction using the focal variation method as proposed by Van Dyck and Op de Beeck proceeds in two stages. First, the complex image wave is retrieved by data extraction from a parabola situated in three-dimensional Fourier space. Then the objective lens spherical aberration, astigmatism and defocus are corrected by simply dividing the image wave by the wave aberration function calculated with the appropriate objective lens aberration coefficients which yields the exit-surface wave.
The use of radial density plots to calibrate images of frozen-hydrated specimens
Authors: Belnap David M. , Olson Norman H. , Grochulski Witold D. , Baker Timothy S. 
Published: June 2020

Accurate magnification calibration for transmission electron microscopy is best achieved with appropriate external or internal standards. The use of the icosahedral polyoma virus as a standard in frozen-hydrated preparations was previously described. This method used the known diameter of polyoma (from x-ray measurements) as a reference to calibrate the diameters of other viruses. Measurements were made from circular averages computed from individual particle images or from an average image of many individual particle images. The measured diameters of several different spherical viruses are in good agreement with measurements of the same viruses made with x-ray crystallographic and solution scattering techniques.We found, however, that it is very difficult to accurately measure particle diameters in images taken from frozen-hydrated specimens. This difficulty is attributable to several factors including i) uncertainty about the solvent density level, ii) superposition of density features that occur in two-dimensional projections of three-dimensional objects, iii) uneven outer surfaces of virus particles, iv) characteristically high noise and low contrast levels in micrographs, and v) contrast transfer function (CTF) effects.
Structure hierarchy in liquid crystalline polymers
Authors: Sawyer Linda C. 
Published: June 2020

Structure models have been developed for the liquid crystalline polymers (LCPs), showing the existence of fibrillar hierarchies for both the lyotropic aramids and the thermotropic aromatic copolyesters. Hierarchies of structure have also been observed for biological materials. The nature of the smallest nanostructure that aggregates, typically microfibrils, and their interaction, are important in understanding the behavior of the material. This paper discusses the first application of scanning tunneling microscopy (STM) and field emission scanning electron microscopy (FESEM) to image the microfibrils in LCPs, in the 1-10 nm size range, resulting in a new LCP structural model.The structure model proposed earlier, was based on the study of Vectra®thermotropic LCP moldings and extrudates, and Vectran®and Kevlar®fibers. The model resulted from characterization by light microscopy, and transmission and scanning electron microscopy. Recent studies of similar fibers by STM and low voltage FESEM has provided additional insights. Details of single microfibrils and their aggregation into fibrils and macrofibrils was shown.
The 50 years before the Electron Microscope: From electron to electron lens — hans busch and the “Göttingen Group”
Authors: Rudenberg H. Gunther 
Published: June 2020

Much of the research to characterize the electron at the turn of the century was made by physics professors at Göttingen University in Germany. Their efforts led their student Hans Busch to experiment and later to analyze the focusing action of a magnetic coil. With this he gave birth to the field of electron optics. Little known are either the delays associated with his discovery or the contributions of others in the “Göttingen Electron Group.”In 1881, fifty years before the invention of the electron microscope, Rieke in Göttingen analyzed the constriction of the canal rays in a Crookes tube by a surrounding magnetic coil. Next, in 1897, which was a particularly exciting year in the history of the electron, Braun conceived the cathode ray oscillograph tube - now named for him in Europe - and J. J. Thomson in England made fundamental measurements on the electron. Also that year Wiechert, who must be recognized as co-discoverer of the electron, made similar measurements in Königsberg. After his appointment to Göttingen later in 1897 there followed a decade of intensive experimental research on the e/m ratio and characteristics of the electron by a half-dozen Göttingen physics professors (e.g. desCoudres, Kaufmann, Rieke, Simon, Stark, Wiechert).
Early contributions to the electron microscope: The relevant work and patents of reinhold rüdenberg
Authors: Rudenberg F. Hermann , Rudenberg H. Gunther 
Published: June 2020

Few know that Reinhold Rüdenberg studied with the “Göttingen Electron Group” in 1906-8, that he was the first to detail the electron microscope in 1930-31 in Germany, that in the 1940's he contributed to the Farrand electron microscope, or that he conceived a number of other electron beam devices. Histories of the electron microscope seldom cite his work, and then only denigrate his role. Our objective here is to correct this misconception.Reinhold Rüdenberg first demonstrated his interest in electronic devices as a high school junior in 1899 when he built a Rühmkorff induction coil which he used to power an x-ray tube and to generate Hertzian waves. While still a student of electrical engineering at Hannover, he applied for his first patent, on a radio oscillator, and published the first of over 100 technical articles. With a Doctor of Engineering from Hannover he was appointed instructor under L. Prandtl at the University of Göttingen.
A TEM study of the microstructure of avian eggshells
Authors: Xiao S. Q. , Baden S. , Heuer A. H. 
Published: June 2020

The avian eggshell is one of the most rapidly mineralizing biological systems known. In situ, 5g of calcium carbonate are crystallized in less than 20 hrs to fabricate the shell. Although there have been much work about the formation of eggshells, controversy about the nucleation and growth mechanisms of the calcite crystals, and their texture in the eggshell, still remain unclear. In this report the microstructure and microchemistry of avian eggshells have been analyzed using transmission electron microscope (TEM) and energy dispersive spectroscopy (EDS).Fresh white and dry brown eggshells were broken and fixed in Karnosky's fixative (kaltitanden) for 2 hrs, then rinsed in distilled H2O. Small speckles of the eggshells were embedded in Spurr medium and thin sections were made ultramicrotome.The crystalline part of eggshells are composed of many small plate-like calcite grains, whose plate normals are approximately parallel to the shell surface. The sizes of the grains are about 0.3×0.3×1 μm3 (Fig.l). These grains are not as closely packed as man-made polycrystalline metals and ceramics, and small gaps between adjacent grains are visible indicating the absence of conventional grain boundaries.