bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure of ribosomes from a thermophilic bacterium
Authors: Dickie Janet , Kyle Karen , Flannigan Derrick , Harauz George 
Published: June 2020

The most direct and informative probe of ribosome structure is electron microscopy (EM), of negatively stained and antibody-labelled specimens. Ribosomes from Escherichia coli have been the most intensively studied, although those from other prokaryotes and eukaryotes have also been imaged [e.g., 3, 4, 5],The amount of structural information obtained from electron images can be significantly increased using multivariate statistical analysis and classification techniques [e.g., 6]. Noisy electron micrographs of single particles are sorted according to their principal features, and average images formed with an enhanced signal-to-noise ratio and better reproducible resolution. The class averages represent projections from which a three-dimensional reconstruction can be computed.Thermus aguaticus is a species of extremely thermophilic bacteria isolated from environments such as hot springs. This species possesses macromolecular enzyme complexes with a great thermostability which must be reflected somehow instructural differences. In this study, we investigate the structures of ribosomes and ribosomal subunits from this bacterium.
Two dimensional crystals of botulinum toxin, serotype B
Authors: Morgan D.G. , DasGupta B.R. , Stubbs G. , Robinson J.P. 
Published: June 2020

Botulinum toxin is a powerful, protein neurotoxin produced by Clostridium botulinum which exerts its toxic action by inhibiting the release of acetyl choline. There are several immunologically distinguishable types of botulinum toxin and most of these have been shown to bind the ganglioside GTlb. The ganglioside binding property of these neurotoxins has allowed us to prepare two dimensional crystals of serotypes A, B, and E. We report here our preliminary observations of two dimensional crystals of serotype B.Type B botulinum toxin was purified by methods reported by DasGupta and Woody. The two dimensional crystals were prepared by slightly modified procedures used previously to prepare similar crystals of tetanus and cholera toxins. Purified toxin was dialyzed into citric acid-sodium phosphate buffer at pH 4.0 to 6.5 and ionic strength of about 0.04. Dialyzed toxin was placed into the wells of microtiter dishes in 20 μl volumes at a concentration of fifty to one hundred μgm per ml. The toxin solutions were then layered with one to two μl of a solution of one to two mg per ml of egg lecithin (Sigma Cat. No. P- 2772) in chloroform containing five to ten percent by weight of the ganglioside GT1B (Supelco Cat. No. 4-6035). The microtiter dishes were then placed in the cold and crystallization was allowed to proceed for one to four days at 4°C. The crystals were then picked up on carbon coated electron microscope grids, negatively stained with one to two percent uranium acetate and examined in the electron microscope.
Correlation between myocardial glutathione content and extent of ischemia-reperfusion injury
Authors: Lee C. Y. , Singh Amar , Lee Kevin J. , Goldfarb Roy D. , Tsan Min-Fu 
Published: June 2020

Considerable evidence suggests that myocardial injury may occur during reperfusion of the ischemic myocardium. Reactive oxygen species are generated during reperfusion which may play an important role in the genesis of myocardial reperfusion injury. Glutathione (GSH) is an important antioxidant in the heart. A decrease in myocardial GSH content has been observed during ischemia and reperfusion of the ischemic myocardiijm. We hypothesized that this depletion of GSH may be detrimental to the ability of the ischemic myocardium to protect itself against reactive oxygen species during reperfusion.In this study, anesthetized open chest pigs were subjected to coronary occlusion for 45 minutes and 2 hours reperfusion. Myocardial GSH was experimentally depleted by pretreatment with buthionine sulfoximine (BSO), a potent inhibitor of cellular GSH synthesis, and was augmented by intravenous administration of GSH. For ultrastructural study multiple subepicardial biopsies 3 mm deep were taken from myocardium supplied by the occluded artery. The biopsies were processed by routine procedures. Thin sections were stained with uranyl acetate and lead citrate and examined with a Philip EM 300 electron microscope.
Ultra-high resolution cinematic digital 3-D imaging of the cell surface by field-emission scanning electron microscopy
Authors: Peters Klaus-Ruediger , Fox Martin D. 
Published: June 2020

Field emission scanning electron microscopes (FSEM) establish high resolution on rugged bulk surfaces. However, often visualization and recognition of image details are hindered by low contrasts. Retrieval of such obscured image information is possible with three-dimensional (3-D) imaging.3-D information can be accessed in several ways. At low magnifications direct TV-rate imaging is possible allowing continuous relocation of the specimen and deduction of 3-D information from dynamic changes of perspectives and parallax. Additionally, two images from different stereo perspectives can be simultaniously produced and 3-D information can directly be displayed through optical or electronic devices (stereo imaging). The combination of dynamic perspective changes and stereo-presentation matches the 3-D information input of the human visual system and provides an optimal tool for visual 3-D pattern recognition.At higher magnifications (>~10,000-20,000x) real time stereo imaging is not possible. 3-D information display becomes limited to stationary perspective displays generated with long frame times.
Correlative transmission and high-resolution scanning electron microscopic studies on pituitary cells
Authors: Tai S. 
Published: June 2020

Extensive cytological and histological research, correlated with physiological experimental analysis, have been done on the anterior pituitaries of many different vertebrates which have provided the knowledge to create the concept that specific cell types synthesize, store and release their specific hormones. These hormones are stored in or associated with granules. Nevertheless, there are still many doubts - that need further studies, specially on the ultrastructure and physiology of these endocrine cells during the process of synthesis, transport and secretion, whereas some new methods may provide the information about the intracellular structure and activity in detail.In the present work, ultrastructural study of the hormone-secretory cells of chicken pituitaries have been done by using TEM as well as HR-SEM, to correlate the informations obtained from 2-dimensional TEM micrography with the 3-dimensional SEM topographic images, which have a continous surface with larger depth of field that - offers the adventage to interpretate some intracellular structures which were not possible to see using TEM.
Fixation and conductive staining by tannin-RuO4 for transmission and scanning electron microscopy
Authors: Takahashi Gen 
Published: June 2020

Ruthenium tetroxide(RuO4) was first used as a stain in histology by Ranvier in 1887. Its use in TEM as a fixative or stain was reported by Gaylarde et al. However,the preservation of the cellular ultrastructure was very poor after RuO4 fixation alone, because RuO4 is a far more vigorous oxidant than osmium tetroxide. Peltari et al reported that a preceeding glutaraldehyde fixation helped to stabilize the ultrastructure, although the penetration of RuO4 into the tissue was poor.In the present study, RuO4 has been found to be a useful fixative and staining reagent with the prerequisite of using RuO4 as a postfixative after prefixation with tannic acid (TA)-glutaraldehyde(GL) for thin-section TEM(TA-RuO4 method) or after preceeding osmication followed by TA mordanting for non-coating SEM(OsO4-TA-RuO4 method).TA-RuO4 method for thin-section TEM
The polar development of membrane structure during spermiogenesis by freeze fracture and double replica technique
Authors: Liankai Dang 
Published: June 2020

With the developing process from the spermatid to the sperm, the great changes of membrane structure are token place both in plasma membrane and nuclear membrane. This note will report the development of polarization in membrane and the distribution of nuclear pores and protein particles during spermiogenesis, and also compare the number of protein in P-face with that in E-face.Mice, Rats, Rabbits and Dogs were operated by taking out the seminiferous tube. It was fixed in 2.5% glutaradehyde for 2 hrs 5 washed in cacodylated buffer, and then the sample was put in to 30% glycerol solution for 6-12hrs. Samples were put into liquid nitrogen rapidly and afterwards moved to BALZAR BAF-400D instrument to get Freeze-Fracture replica and double replica for observation with TEM.The expression and the development of the polarization in membrane structure of the spermatid. The spermatid in different stepshas different characteristics and there is more polarization for membrane structure following spermiogenesis.
Crystalline-like structure in sperm membrane of Chinese Rhodeus sinensis, Acheilognathinae
Authors: Guan Ting-Lu , Yang Yi 
Published: June 2020

It is well know that the spermatozoa are highly polarized cells. The membrane of mammals sperm have been studied in detail. The results have shown are markable diversity of structure with in an otherwise common place unit membrane. However, very few papers were dealt with teleost sperm membrane. Our privious report shows that Carassius auratus (Cyprinidae) sperm membrane have differentiated with regional specificity just like those in mammals. In general, intramembrane protein particles are highly organized at certain are as in the head plasma membrane forming crystalline-like structure, in contrast, rest areas of plasma membrane contain many random dispersed particles. The present study has shown the existence as well as the characteristics of crystalline-like structure in sperm membrane of Chinese Rhodeus sinensis, Acheilognathinae, Cyprinidae.In spawing season the male fish are killed, apart of test is were took out and put into 2.5% glutaraldehyde buffered to pH 7.2 with 0.1mol/L sodium cacodylate.
Fine structure and possible functions of the hermaphrodite duct of some pulmonate snails (Mollusca: Gastropoda)
Authors: Hodgson Alan N. 
Published: June 2020

The hermaphrodite duct of pulmonate snails connects the ovotestis to the fertilization pouch. The duct is typically divided into three zones; aproximal duct which leaves the ovotestis, the middle duct (seminal vesicle) and the distal ovotestis duct. The seminal vesicle forms the major portion of the duct and is thought to store sperm prior to copulation. In addition the duct may also play a role in sperm maturation and degredation. Although the structure of the seminal vesicle has been described for a number of snails at the light microscope level there appear to be only two descriptions of the ultrastructure of this tissue. Clearly if the role of the hermaphrodite duct in the reproductive biology of pulmonatesis to be understood, knowledge of its fine structure is required.Hermaphrodite ducts, both containing and lacking sperm, of species of the terrestrial pulmonate genera Sphincterochila, Levantina, and Helix and the marine pulmonate genus Siphonaria were prepared for transmission electron microscopy by standard techniques.
Transmission Electron Microscopy of testes in mice treated with gossypol acetic acid
Authors: Majumdar S.K. , Khanna Amit 
Published: June 2020

Recent studies have shown that gossypol acetic acid, a natural compound isolated from cotton seeds, is an effective and reversible male contraceptive in animals including humans. Gossypol has also demonstrated uncoupling activity in mitochondria and it is assumed that this is the major biochemical effect of the compound. Moreover, other studies have shown a variety of ultrastructural damage caused by gossypol in rat testes. Since little information on the ultrastructural effects of gossypol in mouse testes is available, this study was undertaken to evaluate the effects of the compound on testicular cells and sperm in DBA/2J mice.Gossypol acetic acid purchased from the Sigma Chemical Co., St. Louis, Missouri, was used for this study. The compound was mixed in olive oil and was administered orally to four groups of mice. Each group received either 0 (control), 10, 20 or 40 mg/kg of the agent twice per week. The mice were sacrificed in pairs at 3, 6, 9 and 12 week intervals. Reversibility of gossypol was studied on mice allowed to recover for 15 weeks after the last treatment.
Ultrastructural analysis of collagen formation in the developing primate amnion
Authors: King Barry F. , Fry Grete N. 
Published: June 2020

The amnion surrounding the mammalian embryo consists of the amniotic epithelium facing the amniotic cavity, a layer of extraembryonic mesoderm bordering the exocoelom and an intervening layer of extracellular matrix (Fig. 1). During gestation the amnion expands remarkably to acommodate the rapidly growing embryo. In this study we have examined the process of collagen fibril formation in the developing amnion of the rhesus monkey between 20 and 60 days of gestation.Most cytological evidence of collagen fibril formation was observed in association with the extraembryonic mesodermal cells rather than the amniotic epithelium. The mesodermal cells h ad abundant cisternae of rough endoplasmic reticulum and a prominent Golgi apparatus. Elongated secretory vacuoles were associated with the Golgi apparatus and often contained parallel aggregates of fine filaments (Fig. 2). In some secretory vacuoles, periodic densities also were observed. Some striated collagen fibrils were observed in an apparent intracellular location in long, membrane-limited compartments (Fig. 3). Still other striated fibrils were observed in dense bodies, presumably lysosomes (Fig. 4).
STM of macromolecules
Authors: Allison D. P. , Thompson J. R. , Jacobson K. B. , Warmack R. J. , Ferrell T. L. 
Published: June 2020

Beginning in 1982 when the first images were reported, the development of the scanning tunneling microscope (STM) has revolutionized microscopy in the 1980’s. Although the primary applications are for research on metal and semiconductor surfaces, success in imaging a number of biological samples, mounted on a variety of conductive surfaces, have established STM as a valuable emerging technology in biological research.In 1987 we began our biological STM studies using tobacco mosaic virus (TMV), an easily identifiable rod shaped virus, to test the feasibility of using STM on naked biological samples. We deposited TMV by spraying an aqueous solution of the virus onto evaporated or sputter-coated palladium-gold (Pd/Au) films supported on flat mica surfaces. Although TMV could be clearly identified, its observed width was typically 70-100 nm instead of the known diameter of the virus, 18 nm. On evaporated Pd/Au substrates, tip traces revealed structures elevated above the substrate surface suggesting that the virus became coated with Pd/Au allowing normal conduction to occur. On sputter-coated substrates tip traces revealed depressed substructures.
Topological Locationzation of Epitopes on Hemocyanin by Molecular Immunoelectron Microscopy
Authors: Lamy Josette , Motta Geneviève , Boisset Nicolas , Taveau Jean-Christophe , Billiald Philippe , Lamy Jean 
Published: June 2020

The intramolecular localization of an epitope on an antigen (AG) can be deduced from the architecture of the immunocomplex (IC) string. Indeed, the epitope is located in the surface portion of the AG in contact with the antibody (AB). The electron microscope is well adapted to the study of the IC architectures, and allows a direct topological localization of epitopes. In this work, the hemocyanin (Hc) of the scorpion Androctonus australis, a 1800 kDa protein comprising 24 polypeptide chains belonging to 8 different types, was used as the AG.Sixteen epitopes were located on the Aa6 subunit using a double approach. First, the architecture of the IC strings composed of native 24-meric Hc and monoclonal antibodies (MABs) was studied by electron microscopy and image processing. Second, the relative positions of the epitopes were determined using IC containing the free subunit.To determine the architecture of IC strings containing 24-meric Hc, whole Hemolecules were incubated with purified MABs specific for the Aa6 subunit, then the ICs were purified by gelfiltration on AcA 34, negatively stained with 2% uranylacetate, and observed in the electron microscope (Fig. 1).
Scanning Electron Microscope Reveals Striking Differences in Cytopathic Effects of Equine Herpesvirus (EHV) Strains
Authors: Brako Emmanuel E. , Phaire-Washington L. , Brown Allison , Brako Norma 
Published: June 2020

The phenomena of cytopathic effects (CPE) i.e., those virus-induced morphological changes in cultured cells observable at the level of light microscopy are commonly used in presumptive diagnosis of viral infections. The cytomorphological changes are similar for many viruses in the same Family or Genus. For example, in LLC-RK1 cell monolayers both EHV type 1-strain KyD (EHV-1) and EHV type 2-strain LK (EHV-2) cause focal cell rounding and polykaryocytosis which can be observed by phase-contrast microscopy (LM). To determine whether external and internal ultrastructural differences exist in LLC-RK1 cells (American Type Culture Collection # CCL 106) expressing CPE, cells were infected with each virus and processed for scanning electron microscopy (SEM).Monolayer cultures of LLC-RK1 cells on 12 mm glass coverslips were inoculated with EHV-1 or EHV-2 at low input multiplicity of infection. After an hour’s adsorption at 37 C, residual inoculum was removed, and cultures were washed twice with serum-free medium and incubated in growth medium at 37 C.
Correlative Video Light, Immunofluorescence, and Electron Microscopy of Chromosome Attachment to the Forming Vertebrate Spindle: Implications for Force Production During Mitosis
Authors: Rieder Conly L. , Alexander Stephen P. , Hayden John , Bowser Samuel S. 
Published: June 2020

This abstract summarizes a number of recently published observations from this laboratory on the formation of the mitotic spindle (1-3), and on the dynamic behavior of spindle microtubules (4).Since chromosome movement during mitosis is, for the most part, directed towards a pole the emphasis of most mitosis research is to elucidate the molecular force-producing mechanism(s) behind this movement. Past studies reveal that poleward chromosome motion is dependent on the attachment of spindle microtubules (MTs) to the kinetochore of the chromosome. However, the origin of these MTs and their role in force production remain controversial. It is similarly unclear whether prometaphase and anaphase chromosomes are moved by the same, or a different, force-producing mechanism(s).The mitotic spindle of cultured newt (T. granulosa) pneumocytes forms in an optically clear region of cytoplasm defined by a cage of keratin filaments (1). As in other cell types possessing an astral spindle, chromosomes in newt pneumocytes that are positioned closer to one pole at nuclear envelope breakdown initially form a monopolar attachment to, and move towards, that pole.
Visualization of the Cytoskeleton by Cryofixation, Immunoelectron Microscopy and 3-D Reconstruction Techniques
Authors: McDonald Kent 
Published: June 2020

We are using various combinations of the following techniques to study cytoskeleton structure and function: cryofixation by high pressure freezing, double jet or plunge freezing; freeze substitution; cryosectioning of frozen hydrated or frozen substituted cells; EM immunolocalization; high voltage and conventional cryoelectron microscopy; serial sectioning (thick and/or thin); and computer-mediated 3-D reconstructions from serial sections.One area where many of these tools and techniques are called into play is in the ultrastructural analysis of developmental mutant phenotypes in Drosophila. Staged embryos are ultrarapidly frozen by high pressure freezing then divided into three groups for further processing. One group is freeze-substituted in osmium-acetone then flat embedded and sectioned for examination by high voltage or conventional microscopy. This allows us to evaluate the quality of cryofixation and the percentage of well frozen embryos. From this material we will also cut serial sections which will be used to make 3-D models of the area of interest. The second group of frozen embryos will be put directly into a Reichert FC4 cryoultramicrotome and sectioned at -150 C. The cryosections are then examined in the cryostage of the high voltage EM. The third group is freeze-substituted in methanol plus aldehyde fixatives in preparation for immunological studies.
The Use of Noncryoprotected Frozen Tissue in Diagnostic Electron Microscopic Pathology
Authors: Minda J.M. , Lubensky I. , Pietra G.G. 
Published: June 2020

Aldehyde fixatives are the reagents of choice to preserve human tissues for diagnostic electron microscopic examination. Since the need for ultrastructural studies is often unanticipated at the time of frozen sections, tissues are not routinely fixed in aldehydes. Alternatively, even if properly fixed, the sample may not contain representative lesions. This may require retrieval of tissue for electron microscopy from paraffin-embedded blocks or slides in which preservation of fine structure is markedly inadequate.The present study was undertaken to evaluate the use of noncryoprotected frozen tissue for diagnostic electron microscopic evaluation. The tissues samples from the following lesions were available for study: bronchial carcinoid, duodenal somatostatinoma, granular cell tumor of breast, interstitial myocarditis (from an autopsy). The effect of the rapidity of freezing on ultrastructural preservation was studied in a normal rat liver. Each case had its own control in companion samples that had been routinely fixed by immersion in 2.5% glutaraldehyde and 2% paraformaldehyde in 0.1M sodium cacodylate, pH = 7.4, (Karnovsky’s fixative).
Human Breast Carcinoma (Ultrastructural Observation of Ductal Carcinoma in 346 Patients)
Authors: Elliott Robert L. , Elliott Mary C. , Ledford Lindsay 
Published: June 2020

Tissue from 346 patients with ductal carcinoma of the breast was fixed in Zambonis; post fixed in 1% OsO4; embedded in a Med Cast Resin; and thin sections were cut on an ultramicrotome. They were stained with uranyl acetate and lead citrate and examined in a Hitachi H-600 electron microscope.Histologically, the tumors were intraductal and invasive. Ultrastructurally, lesions ranged from very well differentiated to extremely anaplastic with all gradations in between. Well differentiated tumors have large round nuclei with evenly dispersed chromatin and the cytoplasm contains tubular granular endoplasmic reticulum, free ribosomes and normal appearing ovoid and rod-shaped mitochondria (Fig. 1). The more anaplastic tumors have large irregularly shaped nuclei with clumped peripheral chromatin and very bizarre nucleoli. The cytoplasm has sparse endoplasmic reticulum and mitochondria are virtually absent, however, ferritin granules are abundant (Fig. 2 and 3). The anatomical presence of ferritin supports a biochemical study of tissue ferritin concentration in breast carcinoma.