bluuebunny/crossref_metadata_2025_split huggingface dataset:
Where is the prolamine located in rice endosperm?
Authors: Wu Hsin-Kan , Chung Mei-Chu 
Published: June 2020

In one of our earlier papers (Wu et al. 1978), we suggested that glutelin is the major composition of the round storage protein bodies although they also contain relatively more prolamine than the angular one does. Immunochemical studies of Krishnan et al. (1986) later showed the presence of glutelin in the irregularly-shaped (angular) protein bodies while the prolamines were found in the round ones. Our recent experiment using protein A-gold technique found that prolamine is mainly deposited into the angular protein bodies.Small blocks (1 mm3) of 7 DAF (days after flowering) caryopsis of Orvza perennis were fixed with 3% paraformaldehyde and 3% glutaraldehyde in 0.1M sodium phosphate, pH7.4, dehydrated in a graded ethanol series and infiltrated with Spurr’s resin. Thin sections, after gold labeling, were stained with uranyl acetate and lead citrate. Rabbit antibodies were raised against purified prolamine. Protein A-gold sol complex was prepared based on the technique of Horisberger et al. (1977).
Scanning Electron Microscopy of the gill arch of Plecostomus commersonii (Pisces)
Authors: Fanta E. , Eiras-Stofella D. R. 
Published: June 2020

The fish Pleaosomus commersonii occurs in Brazilian rivers and has the whole body covered with shields. It can remain out of the water for long periods without dying and is very resistant to environmental changes. It has 4 U-shaped branchial arches (Fig. 1a) with two special features: the absence of hooks or spines in the gill raker, in the pharyngeal region; and the presence of a second row of filaments, external to the branchial filaments (Fig. 1b).Through SEM it was possible to describe externally both structures. The branchial filaments have flat secondary respiratory lamellae, which show irregular thickness (Fig. 2). At their tip, buds with one or more openings can be seen. The primary lamellae have an irregular epithelium with many round structures between the flat polygonal epithelial cells. The extra filament has a different aspect: it has no secondary lamellae. The side close to the branchial filament is different from the opposite one; the epithelium resembles that of the primary lamella.
Effects of long-term exposure to modified Karnovsky’s fixative on tissue ultrastructure
Authors: White S. L. , Hoover D. M. 
Published: June 2020

In toxicology studies, the potential to store tissues in the primary fixative offers the flexibility to collect selected specimens and hold them for further processing contingent upon findings in other areas such as histopathology and biochemistry. This would allow conservation of resources and time by eliminating the need to duplicate studies specifically for electron microscopy. Previous investigators have dealt primarily with the morphological effects on the tissue produced by various fixatives, buffers, and osmolalities while using optimum processing schedules. However, little information is available on longterm exposure to the primary fixative25. In the present study, we investigated the ultrastructural morphological effects on tissues stored 1 month or 6 months in modified Kamovsky's fixative as compared to tissues given a 3 hr exposure to the primary fixative.Three male and 3 female Fisher 344 rats ages 6 to 7 weeks were prepared for whole body fixative perfusion by giving an I.V. heparin sodium injection followed by ether anesthesia.
Localization of lectin binding sites in the lens of rats: A study by a labeling frozen thin-section method
Authors: Tanaka Toshikazu , Sakai Masahiro , Ihara Nobuo , Honda Yoshihito , Ogawa Kazuo 
Published: June 2020

In various tissues, many investigators have reported that sugar residues of cell-membrane proteins participate important functions such as cellular recognition, adhesion and differentiation. As an organ, the lens has distinct polarity from anterior to posterior face as one of its unique structural characteristics. However, a only few studies have been performed about the localization of sugar residues at light-microscope level. The purpose of this study is to detect lectin binding sites in lenses of normal rats and Ihara Cataract Rats (ICR) by utilizing a labeling frozen thin-section method.The lectins, concanavalin A (Con A) and wheat germ agglutinin (WGA) were used in this study. Wistar rats and ICR rats which develop hereditary cataracts were used as experimental animals. For light microscopy, frozen semi-thin sections were stained with the lectins, using an avidin-biotin-complex procedure and visualized by incubation with 0.1% diaminobenzidine (DAB) and 0.01% H2O2 in PBS.
Ultrastructural localization of secretory glycoconjugates in the gallbladder epithelium of the Richardson’s ground squirrel before and during cholesterol gallstone formation
Authors: MacPherson Brian R. 
Published: June 2020

Hypersecretion of mucin is a critical feature of gallbladder epithelial cells in ground squirrels fed a 2% cholesterol-enriched diet for the induction of cholesterol gallstone formation. The timing of this physiological response indicates a potential role for mucin as an initiator of cholesterol crystal nucleation from supersaturated bile. There is little information regarding the specific type of glycoprotein secreted by gallbladder epithelia and routine light microscope histochemistry proved unproductive for detection of specific glycoprotein types being synthesized as the intracellular accumulations were not large enough to permit visualization of a colored precipitate. Ultrastructural histochemistry was utilized to differentiate between the two main mucin types secreted by the gastrointestinal tract - sulphated and sialomucins.Two ultrastructural methods utilizing the histochemical basis of the high and low iron diamine techniques were used. The high iron diamine (HID) technique imparts density to sulphated complex carbohydrates while the low iron diamine (LID) method imparts density to acidic glycoconjugates.
EM and biochemical determinations of chromaffin cell ecto-ATPase activity
Authors: Kriho V. , Pappas G. D. , Becker R. P. 
Published: June 2020

Exocytotic granules of bovine chromaffin cells contain both catecholamines and ATP. Upon stimulation, the granule contents are discharged into the extracellular space. Catecholamines are eventually hydrolyzed. The resultant choline is then taken up by the cell for recycling. The fate of the extracellular ATP has not been determined. Ecto-ATPase activity has been localized at the plasma membrane of the chromaffin cell in the adrenal gland. This ATPase activity may play a role in the local metabolism of the released ATP.Our present study further investigates this ecto-ATPase activity, using biochemistry and EM cytochemistry, on isolated, intact bovine chromaffin cells. Our biochemical results are seen in the histogram of Fig. 1. ATPase assays show considerable ATPase activity when both Ca++ and Mg++ are present in physiological concentrations in the incubating solution. Even when Ca++ is omitted from the incubating solution, a great deal of ecto-ATPase activity is still demonstrated. Omitting Mg++ from the medium, however, reduced the level of ATPase activity by 91%.
Hydrated cryo-section studies of endocytic structures in cells containing internalized gold markers imaged by TEM
Authors: McDowall Alasdair , Griffiths Gareth 
Published: June 2020

A question often raised when interpreting ultrastructural TEM images of sectioned biological material is, “to what degree do the se images reflect structure in vivo?”. It is difficult to unambiguously answer this question by classical electron microscopy alone, due to the necessity to use chemical procedures whose mechanism of action is never completely understood. More commonly, ultrastructural analyses are interpreted from information obtained using a variety of approaches and techniques.We describe here structures of the endocytic pathway in cultured cells as seen in TEM following two cryo-preparative procedures: 1) Frozen thin sections of chemically fixed and sucrose infused cells (the Tokuyasu technique), and 2) the frozen hydrated technique on non-chemically fixed cells. The Tokuyasu technique offers one of the best methods available for intracellular localization of membrane antigens. In the present study, labelling living cells with colloidal gold conjugates could be complemented by further labelling fixed cryo-sections of the same cells. This was achieved with a range of antibodies and different sizes of protein A gold probes. From this and other data, a current model for the endocytic pathway evolved in which thre e major compartments exist between the plasma membrane-derived clathrin coated vesicles and the degredative lysosomes. Specifically, these compartments are an early endosome, an endosome ‘tran sport’ vesicle and the pre-lysosomal compartment/late endosome.
Quantitative Examination of Semicrystalline Polymers Via Atomic-Force Microscopy, Transmission Electron Microscopy, and Small-Angle X-Ray Scattering
Authors: Bischel M. S. , Balijepalli S. , Schultz J. M. 
Published: June 2020

The Atomic Force Microscope (AFM) has been used to reliably measure lamellar thickness in semi-crystalline polymers, and to distinguish phases within blends of these polymers.Traditionally, lamellar thicknesses of semi-crystalline polymers have been determined by (1) measuring structures directly from TEM micrographs or (2) using small angle X-ray scattering (SAXS) spectra. In the first case, the sample must either be etched and replicated, or stained with heavy metals or chlorosulfonic acid to reveal the lamellar structures. Good SAXS measurements require access to a synchrotron, or rotating anode diffractometer. In contrast, the AFM has been used to relaibly measure the lamellar structures in polymer specimens which have undergone minimal sample preparation.The tapping mode of operation of a Digital Nanoprobe AFM has been used on the free surfaces of polyethylene oxide (PEO) specimens to determine lamellar thicknesses that are in excellent agreement with measurements obtained from both TEM and SAXS. Examples of such comparisons in the existing literature are few.
Characterization of triological sealing system components using scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS)
Authors: Shuster Mark , Deis Mick 
Published: June 2020

A system approach to solving the tribological problems associated with sealing joints implies comprehensive investigation of all the components. To recognize the root cause of any problem and formulate the required performance for extended reliability we have to evaluate any changes in the system as quantitatively as possible. Any measurable parameters, including geometry, density (porosity), hardness distributions, microstructure and grain size changes observed during routine metallurgical analysis could provide evidence of the root cause of failure. In the head-gasket-block sealing system of the internal combustion engine, the EDS evaluation of the chlorine and sulfur distribution through the head gasket flange fracture in conjunction with analysis of the sludge between the head, block and gasket surfaces pointed to the corrosive nature of the gasket flange cracking.This approach is even more useful for the closed tribological system of telescopic hydraulic cylinders or rotary axle shaft oil seals.
Low-Voltage, High-Resolution, Scanning Electron Microscopy of Platelet-Bound Fibrinogen
Authors: Simmons S.R. , Albrecht R.M. 
Published: June 2020

An essential element in blood clot formation is fibrinogen-mediated platelet aggregation. Fibrinogen is an adhesive plasma protein which binds to the αIIbp3 integrin on activated platelet surfaces. Platelets do not aggregate in the absence of fibrinogen binding, and fibrinogen bound to surfaces of platelets in aggregates is localized to regions of platelet-platelet contact. The fibrinogen molecule is symmetrical and bifunctional and may directly bridge the gap between platelets to bind to receptors on two adjacent platelets. However, the precise mechanism by which fibrinogen links platelets is unclear.Previously we have utilized colloidal gold labeling with correlative light and electron microscopy to investigate the binding of fibrinogen to receptors on surfaces of spread, substrate adherent platelets. The initial binding of gold-conjugated fibrinogen (FgnAu) and subsequent ligand-triggered receptor movement was followed on living platelets by video-enhanced light microscopy. Fibrinogen receptors initially are dispersed over much of the platelet surface and move centripetally upon fibrinogen binding, ultimately forming a band of bound fibrinogen on the platelet surface overlying a densely woven band of actin filaments surrounding the central granulomere. After preparation for electron microscopy, the same platelets as were followed in the light microscope were located in the high voltage TEM and the low voltage, high resolution, SEM (Hitachi S-900) and the final locations of the gold labeled receptor/ligand complexes were determined relative to internal or surface ultrastructure, respectively. More recently, we have utilized the SEM operated at low (1-2 kV) beam voltage to examine in detail the binding of unlabeled fibrinogen to platelets. With appropriate specimen preparation, individual cell surface macromolecules can be resolved in situ by low voltage SEM. In addition to the centripetal receptor redistribution seen with FgnAu, unlabeled fibrinogen appeared to undergo self-adhesive interactions following binding to platelet fibrinogen receptors, forming small, branched and globular protein aggregates during translocation across the platelet surface.(Fig. 1)
Z-Contrast Imaging of Grain Boundaries in Semiconductors
Authors: Chisholm M. F. , Pennycook S. J. 
Published: June 2020

Interest in grain boundaries in semiconductors is linked to the application of polycrystalline semiconductors as photovoltaic and interconnect materials. In real devices such as solar cells and MOS structures as well as future devices such as flat-panel displays, the intergranular regions of the polycrystalline solid have a significant effect on the flow of electronic current. These grain boundary barriers exist because the chemical potential of the boundary atoms are shifted from the bulk value by the change in local symmetry. The chemical potential is also changed by impurities, other structural defects, and other phases in the boundary. The lack of knowledge on the atomic structure of grain boundaries is, at present, the greatest barrier to advancements in the understanding of the electrical properties of these defects.The advances of the last few years have provided the tools with which to probe these interfaces at the true atomic scale. One such tool is the high-resolution scanning transmission electron microscope installed at Oak Ridge National Laboratory (VG Microscopes HB603) that can form a 1.27Å electron probe. Images are formed by scanning the probe across a thin sample and using an annular detector to collect electrons scattered to high angles. Because the annular detector collects electrons scattered over a wide range of angles, phase correlations and dynamical diffraction effects are averaged by this annular integration. Thus, an image with incoherent characteristics is produced and retained to relatively large specimen thickness.
Electron Microscopy Over the Internet as an Outreach Tool
Authors: Cousens D. R. , Waddell D. , Cribb B. , Jones M. , Drennan J. 
Published: June 2020

Microscopy is an ideal medium to explore the wider applications of science and technology within the community in science and technology awareness programs. It bridges many individual disciplinary areas in science allowing many different facets of science and technology to be presented within a familiar framework.The development of low cost video-audio conference software at Cornell University and the concurrent installation of Internet connections in Queensland schools at both primary and secondary level have provided an opportunity to enhance the science awareness and community service aspects of the Centres’ operation beyond physical visits by school groups. This increases dramatically the potential audience that can be reached for a given investment of time. It also allows school communities in the more remote areas of the state to have some access to advanced scientific instruments and the applications for which they are used. The project is being initially piloted with schools in regional areas around Brisbane as this provides immediate feedback in the exploratory stages of the program.
A 200kV Comprehensive Analytical Electron Microscope
Authors: Tomita T. , Kawasaki M. , Takeguchi M. , Honda T. , Kersker M. 
Published: June 2020

With the use of a high-brightness electron source, the performance of the analytical electron microscope (AEM) has significantly improved. It features a variety of sophisticated analytical functions, such as X- ray spot analysis, area analysis, electron beam energy analysis, electron diffraction, and phase analysis using a biprism for holography. Here, we report the results of our analysis using a 200kV comprehensive AEM which has an integrated ZrO/W emitter as its optic source. The AEM (JEM- 2010F) is equipped with an X-ray energy dispersive spectrometer (EDS), scanning image observation device (ASID), parallel detection electron energy loss spectrometer (PEELS), and TV camera.(1) X-ray mapping using EDS and ASID With FEG, the probe current in a 1 nm probe is increased by two-order orders of magnitude, and the background noise generated near the sample and in the illumination system is minimized. As a result, EDS analysis features high sensitivity at a minimum detection of 1% weight fraction from an ultra-micro area of lnm diameter.
STEM investigation of the chemistry and bonding changes associated with the grain boundary embrittlement of Cu by Bi
Authors: Keast V. J. , Bruley J. , Williams D. B. 
Published: June 2020

It has long been known that trace amounts of Bi can embrittle Cu after appropriate heat treatments. The Bi segregates to the grain boundaries and weakens them such that failure occurs through intergranular fracture without plastic deformation. This behavior is demonstrated in the scanning electron micrograph of a typical Cu-Bi fracture surface in Figure 1. It is known that the Bi extends for only a few atomic layers into the grains on either side of the grain boundary. This narrow segregation width was been confirmed using Energy Dispersive X-ray Spectroscopy (EDS) on a VG HB603 STEM. Figure 2 shows the ratio of Bi to Cu as the probe is stepped across the grain boundary.The segregation behavior is well understood, however it is not yet properly understood how the Bi causes embrittlement once it is at the grain boundaries. The Bi must change the bonding at the boundaries so that the boundaries become weak and hence the most likely fracture path. The Electron Energy Loss Near Edge Structure (ELNES) coupled with the small probes and high current density available in a field emission STEM can provide information about the localized electronic structure and hence bonding at grain boundaries. Previous investigations indicated that the near edge structure of Cu was altered at the grain boundaries due to the presence of Bi.
EXELFS study of the structure of silica and sodium silicate glasses
Authors: Winkler Dennis C. , Williams David B. , Jain Himanshu 
Published: June 2020

The conventional extended X-ray absorption fine structure (EXAFS) method is not ideal for determining local structure around light elements in a solid. Although the “electron yield” EXAFS technique can be used to increase sensitivity to lighter elements, it is mainly a surface technique. We have employed the extended energy-loss fine structure (EXELFS) technique for determining the local structure (partial radial distribution function, inter atomic distance, and disorder parameter) in oxide glasses, specifically around Si and O in silica and sodium silicate glasses. Because a scanning transmission electron microscope is used, EXELFS also allows high spatial resolution which is particularly useful for a glass prone to phase separation.EXELFS results from the same phenomenon responsible for EXAFS, namely the interference of the
outgoing spherical wave of the ejected electron with portions of itself which have been backscattered
from the neighboring atoms in the solid. This produces oscillations in intensity beyond the absorption edge. These variations in intensity are transformed to radial distribution functions in the same fashion as EXAFS data. EXELFS, like EXAFS, provides local atomic environment information that is element specific.
Tomography of paracrystalline specimens
Authors: Taylor Kenneth A. , Winkler Hanspeter 
Published: June 2020

3-D image reconstruction of objects with no symmetry are produced by combining images of specimens tilted at finely spaced intervals about a single tilt axis. Image fiducials, usually gold particles applied to the surface of the specimen, are used to orient and align the separate views and 3-D images calculated by back projection methods. Electron microscope tomography has developed into a powerful method for producing a 3-D image of objects lacking crystalline symmetry. Crystalline objects are usually reconstructed using Fourier based methods that produce averaged 3-D images. Electron crystallography has become a powerful tool for solving the 3-D structure of proteins at atomic resolution.Paracrystalline objects lie between crystalline and nonperiodic specimens because part of their structure is often well ordered but they have as well a significant disordered part. Muscle is one of the more notable members of this type of specimen because often the actin and myosin filaments form a well ordered array but the crossbridges, i.e. the motor domain of myosin, are much more disordered.
Digital imaging: When should one take the plunge?
Authors: Mansfield John F. 
Published: June 2020

The current imaging trend in optical microscopy, scanning electron microscopy (SEM) or transmission electron microscopy (TEM) is to record all data digitally. Most manufacturers currently market digital acquisition systems with their microscope packages. The advantages of digital acquisition include: almost instant viewing of the data as a high-quaity positive image (a major benefit when compared to TEM images recorded onto film, where one must wait until after the microscope session to develop the images); the ability to readily quantify features in the images and measure intensities; and extremely compact storage (removable 5.25” storage devices which now can hold up to several gigabytes of data).The problem for many researchers, however, is that they have perfectly serviceable microscopes that they routinely use that have no digital imaging capabilities with little hope of purchasing a new instrument.