bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultracytochemical demonstration of sulfhydryl groups in the rabbit erythrocytic membrane
Authors: Ogawa Kazuo , Tanaka Teruo
Published: June 2020

Elucidation of the macromolecular structure of the cellular membrane is one of the most current topics in cell biology. In relation to such study, development of the membrane ultracytochemistry, in particular ultracytochemistry of functional groups, is of great value in elucidation of the structure and function of the cell as well as in filling gap between the morphological findings and the physicochemical or biochemical findings on the cellular membrane. At first development of the methods for amino groups (NH2) was tried and then sulfhydryl groups (SH). In the present report recent findings on SH groups are presented.

Formaldehyde-glutaraldehyde-fixed rabbit erythrocytes, intact or ghost, were used to demonstrate SH groups. SH groups were detected by 4 different ways. Fast blue BBN (FBBBN) method: Specimens were incubated in 0. 5% FBBBN in 0.1M cacodylate buffer, pH 7.4, for 40 to 45 min at 0-4°C, fixed in osmium tetroxide (OT) and processed for electron microscopy (EM).
Correlative LM, SEM and TEM of argentaffin cells
Authors: Frederickson R.G. , Spagnoli D.B. , DeNee P.B.
Published: June 2020

The identification of small numbers of cells containing specific materials or having a particular location in a tissue can be observed cften in light microscopic (IM) sections by selective staining. In contrast, the same cells are often difficult to identify in alternate thin sections on grids by transmission electron microscopy (TEM). Grid bars produce periodic obstructions and consequently prevent the visualization of tissue continuity, making it difficult to identify landmarks. Also, the TEM image of a thin section of tissue does not correlate well with the thicker IM image. This is a matter of interpretation based on the different principles of image formation and the different levels of resolution.

The purpose of this paper is to demonstrate a method which allows the same cells identified by IM to be more easily located in thin sections for TEM. This method combines the principles of backscattered electron imaging (BSI), secondary electron imaging (SEI) and heavy metal staining with scanning electron microscopy (SEM).
Direct observations of semithin sections by the use of TEM and STEM
Authors: Sakai Toshio
Published: June 2020

It has been routin to cut semithin sections to look for desired areas before cutting ultrathin sections for electron microscope studies. A new method made it possible to observe larger semithin sections of epoxy resin-embedded tissue with both light microscope and two kinds of electron microscopes,: Transmission Electron Microscope and Scanning Transmission Electron Microscope.

Samples obtained from kidneys of rats and mice were sliced to 0. 5.mm to 1 mm thickness. They were fixed for 4 hours in Sorensen phosphate buffer of pH 7.4, containing 2 % glutaraldehyde and 1.5 % paraformaldehyde, rinsed in plain buffer for 12 hours (overnight) and postfixed in 1 % osmium tetroxide buffered with phosphate for 90 minutes. The tissu blocks were then embedded in epoxy resin in a ratio of 6:4 or 5:5 by weight, based on the method of Luft.
Scanning transmission electron microscopy and X-ray microanalysis of unstained biological thin sections
Authors: Freeman R. , Griffiths G.W. , Jones A. V. , Leonard K.R.
Published: June 2020

The scanning transmission electron microscope (STEM) has two distinct advantages over the conventional transmission electron microscope (CTEM) for the investigation of low contrast specimens such as unstained thin sections. These are the much higher collection efficiency for scattered electrons and the possibility of electronic enhancement of the image forming signal. The addition of an X-ray analysis system to STEM may also enable the identification of some of the elements contributing to the overall image contrast and to detect individual element concentrations in features of high contrast occurring in the specimens.

Fresh tissue was fixed in 1-2.5% glutaraldehyde in PIPES buffer, quickly dehydrated in ethanol and embedded in epon. Thin (silver/grey) sections were collected on carbon coated copper or nylon grids and viewed in the STEM without further treatment. The microscope used was a Vacuum Generators HB5 STEM with field emission source operating at lOOkV with simultaneous bright field (BF) and dark field (DF) detection systems.
Diffusible ions in amebae studied by scanning electron microscopy and X-ray microanalysis
Authors: Schäfer D. , Zierold K.
Published: June 2020

Calcium ions are involved in the regulation of ameboid movement but, so far, little is known about the distribution of calcium and other electrolyte ions in the amebae. This problem seems solvable by X-ray microanalysis with the scanning electron microscope (SEM). For this purpose Amoeba proteus was placed in the cultivation medium (Chalkey's solution) on the specimen stub covered with aluminum foil. Rapid freezing was done in liquid Freon 12 or propane precooled by liquid nitrogen. The specimens were either freeze-dried at -45° C for 15 hours and then coated with carbon or kept in the deep-frozen state throughout the preparation and investigation procedure by using a special cooling chain method. After coating ice was sublimated in the SEM under visual control until the ameboid structures became visible. Energy-dispersive microanalysis was done at 12.5 keV and 0.1 - 0.5 nA.
X-ray microanalysis of cryofixed skeletal muscle in culture
Authors: Zierold K. , Pietruschka F. , Schäfer D.
Published: June 2020

X-ray microanalysis of electrolyte ions in cells and tissues involves the problem of preserving the distribution of diffusible substances throughout preparation and investigation in the scanning electron microscope. Cryofixation of objects thicker than about 200,um induces considerable freezing artifacts. The dissection of the specimen from the intact tissue also influences the distribution of diffusible ions. With respect to these problems, tissue culture cells seem advantageous, because they need not be dissected from their environment and are small enough to be frozen without ice crystal damage.

Tissue cultures were grown from skeletal muscle of the hindleg of 20-day-old rat embryos on plastic coverslips. Small pieces of the specimens (diameter about 4 mm) were mounted on cupreous specimen stubs with conducting silver paint and frozen in liquid propane.
Quantitative X-ray microanalysis of a mouse cardiac muscle by means of the freeze substitution method
Authors: Mizuhira Vinci , Shiihashi Michiko
Published: June 2020

"Analytical electron microscope": We have deviced a new analytical electron microscope in Japan for the detection of elemental localization in tissues and cells in 1973.

Our analytical EM is basically composed of a JEM 100C transmission electron microscope fitted with a scanning device(ASID-4), a side-entry goniometer stage and an energy dispersive type X-ray microanalyzer unit(EDAX-707B) with an EDIT-Computer system.

Freeze substitution method: We compared the results between the freeze dried and the freeze substituted sections of fresh mouse kidney before the cardiac muscle examination. The results were clear that the freeze substitution method with ether or acetone followed by vinylcyclohexane dioxide (ERL-4206) resin mixture seems superior both in the STEM-image and the X-ray microanalysis to that of the freeze dried method.

Freshly prepared mouse heart muscle was cut in small pieces within a 3 mm3 in size, mounted on an alminum foil, and frozen with cooled methycyclohexane at the liquid nitrogen temperature, after acrolein vapor fixation for 3 min.
The detection of P and Ca by X-ray microanalysis in the cyto-chemical reaction product of alkaline phosphatase in the epithelial surface of the rat duodenum
Authors: Makita Takashi
Published: June 2020

Alkaline phosphatase activity (ALP-ase) can be localized both over the brush border and on the lateral wall of the duodenal columnar epithelium. (Figs.1,2). Dense precipitate can also be observed on or in the mucus ‘bodies’present on the luminal surface. (Figs.3,4). In order to find out whether it is real phosphatase reaction product(lead phosphate) or not, unstained semi-thin sections (3-500 nm) of glutaraldehyde- fixed tissue, were subjected to X-ray microanalysis, after being incubated in an appropriate substrate medium (Mayahara's lead citrate method), post-fixed in buffered OsO4, and embedded in Spurr resin. A scanning transmission electron micrograph(STEM) was first taken at 25-50 kv(JEOL 50A SEM or 100 C TEM),after which the section was analysed by either a wavelength dispersive detector attached to the SEM or an energy dispersive type enfaced to the TEM at 40-60 kv.
Replication of biological specimens at -150°c with an improved freezefracture apparatus
Authors: Pscheid P. , Müller W.
Published: June 2020

It is advantageous to fracture at the lowest temperature possible to minimize the plastic deformation of the specimen. However, the contamination rate is in- versly proportional to the temperature. One way to avoid this problem is to decrease the pressure and therefore the contamination rate.

The present paper describes inexpensive modifications of the Balzer freeze-etch machine (BA 360 M) which reduces the contamination rate of the specimen. This is done by an improvement of the vacuum and a modification in the specimen table.

The vacuum can be improved in the following manner: by desorption of water from the surfaces of the vacuum chamber; by condensation of water in the residual gas mixture of the vacuum on cold surfaces; by minimizing frost build-up at the specimen surface during the transfer to the machine.
Immunoferritin localization of intracellular antigens in positively stained frozen sections
Authors: Tokuyasu K. T.
Published: June 2020

During the past investigations of immunoferritin localization of intracellular antigens in ultrathin frozen sections, we found that the degree of negative staining required to delineate u1trastructural details was often too dense for the recognition of ferritin particles. The quality of positive staining of ultrathin frozen sections, on the other hand, has generally been far inferior to that attainable in conventional plastic embedded sections, particularly in the definition of membranes. As we discussed before, a main cause of this difficulty seemed to be the vulnerability of frozen sections to the damaging effects of air-water surface tension at the time of drying of the sections.

Indeed, we found that the quality of positive staining is greatly improved when positively stained frozen sections are protected against the effects of surface tension by embedding them in thin layers of mechanically stable materials at the time of drying (unpublished).
Aggregation properties of electric eel acetylcholinesterase: a possible mechanism of enzyme association at the synapse
Authors: Cartaud J. , Bon S. , Massoulié J.
Published: June 2020

Electrophorus acetylcholinesterase activity (E.C.3.1.1.7) is associated with several molecular forms (D = 18.5 S, M.W.= 1,150,000; C = 14.4 S, M.W.= 796,000; A = 9 S, M.W. = 410,000; G = 11.8 S, M.W.= 330,000; G' = 7.7 S, M.W.= 165,000 and G” = 5.3 S, M.W. = 70,000). All the lighter forms probably derive from the heaviest (D) which is an asymmetric assembly of three tetramers of catalytic subunits linked by a collagen-like filament or “tail”. The two lighter asymmetric forms, A and C, contain respectively one and two tetramers linked to a tail.

When exposed to low ionic strength conditions, the asymmetric forms of the enzyme associate reversibly into fast sedimenting aggregates (70 S), the process not being correlated with any change in catalytic activity.
Cytochemical study of the plant interphase nucleolus
Authors: Luck B. , Lafontaine J.G.
Published: June 2020

Under light microscopy, plant interphase nucleoli show a heterogeneous organization due to the presence of a coarse, contorted filamentous structure which, at high magnification, may be demonstrated to give rise to the fibrillar zones. This thread-like structure, or nucleolonema, is continuous with extranucleolar segments of chromosomes and corresponds, therefore, to the nucleolar organizer. It is observed that this filamentous structure gradually contracts during prophase and eventually forms a nucleolar secondary constriction. The latter chromosomal segment differentiates during telophase and is intimately involved in the process of nucleolar reformation.

A still unresolved feature of the nucleolonema is the presence of a series of complexly organized lighter areas referred to as lacunae. A dense structure, or core, sometimes observed in the central portion of these lacunae is believed to consist of compact chromatin whereas the surrounding lighter material presumably represents diffuse chromatin. Digestion with deoxyribonuclease as well as high resolution radioautography indicate that DNA is indeed present within the nucleolonema.
Synaptonemal complexes in the mosquitoCulex quinquefasciatus
Authors: Fiil Annelise
Published: June 2020

The presence of synaptonemal complexes between the paired homologous chromosomes at meiotic prophase is a prerequisite for meiotic crossing over, and it may be important for the regular disjunctions of the chromosomes at meiosis I (Moses, 1968; Westergaard and von Wettstein, 1972; Gillies, 1975). Reconstructions of nuclei during zygotene and pachytene have shown that the ends of the synaptonemal complexes in many organisms are attached to the nuclear membrane, often in a polarized fashion (Moens, 1969; Rasmussen, 1976); such a bouquet arrangement of the chromosomes is found in Culex.

Materials and Methods

Ovaries from Culex quinquefasciatus were fixed in glutaraldehyde, followed by 0s04, and embedded in Epon. The synaptonemal complexes were reconstructed from serial sections.

Results and Discussion

Culex has 3 pairs of very long metacentric or slightly submetacentric chromosomes which during pachytene loop around the nucleus several times (Fig. 1). The centromeric regions are fused, and the synaptonemal complexes do not continue through the structure.
Centromeric heterochromatin in phyllotis darwini
Authors: Eduardo Couve M.
Published: June 2020

Centric fusion plays an important role in karyotype evolution as a mechanism of chromosomal change. Centromeric Heterchromatic regions (CeHR) can be observed in optical and electron microscopes and their location during meiotic stages should be fundamental for the occurrence of centric fusion.

This work is concerned with centromeric he terochromatin orientation and cytochemistry of this structure in meiotic male cells of Phyllotis darwini rupestris, obtained from their natural region. This is a Chilean species with diploid number 38, all chromosomes biarmed (meta- and submetacentric). Heterochromatin is always located in the centromere region, except the Y chromosome.

Spreads for light microscopy were made from testicular tissues and stained with Arrighi and Hsu (1971) procedure. For electron microscope pieces of seminiferous tubules were fixed in glutaraldehyde 3% in 0.2M cacodylate buffer pH 7.2 and postfixed in osmium tetroxide 1%. Tissue was stained in block with 5% uranyl acetate, dehydrated in ethanol and embedded in Epon 812.
High resolution autoradiographic visualization of transcription complexes in spread chromatin from mammalian cells
Authors: Fakan S. , Villard D. , Hughes M.E.
Published: June 2020

The technique developed by Miller and collaborators for spreading genetic material allows direct visualization of RNA transcription in the electron microscope. This technique has been applied rarely to mammalian cells as its application seems more difficult in mammalian than in other systems because the concentration of chromatin is generally very high and interpretation of the figures obtained is sometimes difficult. High resolution autoradiography of spread chromatin from cells pulse labelled with 3H-uridine permits us to reveal labelled RNA chains, and at the same time, to confirm the nature of the fibrils visualized within chromatin. The lysis technique we use was previously employed for isolation of chromatin from the same cell strain. Such isolated chromatin exhibits properties well defined from both biochemical and ultrastructural points of view.
Mitochondrial changes related to yolk formation in oocytes of a viviparous teleost
Authors: Azevedo Carlos , Coimbra Antonio
Published: June 2020

Mitochondria have been implicated in yolk formation in amphibians the oocytes of which were shown to contain intramitochondrial yolk crystals. We recently observed, however, in the viviparous teleost Xiphophorus helleri, that mitochondria seem to intervene in yolk accumulation in a different way by developing invaginations of their contour which enclose materials that are later incorporated into yolk globules. Ovaries were fixed in glutaraldehyde—osmium or osmium alone and epon embedded.

In 15 day-old females, at leptotene, oocyte mitochondria appeared closely associated with granulo-fibrilar perinuclear masses identical to other masses situated on both sites of nuclear pores or near the nucleoli (Fig. 1). Granules in all these masses measured 12 nm in diameter and were similar to those forming the nucleolar pars granulosa. At dictyate, while nucleoli became vacuolated and ring-shaped, mitochondria surrounded the granulo-fibrilar masses (Fig. 2), though by the second half of this stage they appeared detached from those masses and showed constrictions and sinuous contours.
Mitochondria microcrystals deposition in some inherited diseases of lipid metabolism.
Authors: Laoussadi S. , Kahan A. , Aubouy G. , Delbarre F.
Published: June 2020

Several patients with Fabry's, Gaucher's diseases and hyperlipoproteinemia type II and with arthropatic manifestations were observed.As no histological explanation for these symptoms was available,an ultrastructural study of synovial tissue was done to establish an anatomoclinical relation.

Material and Methods :synovial membrane samples were obtained by needle biopsies of the knee from three patients with arthropatic manifestations of each disease.They were fixed in 5% glutaraldehyde, postfixed in 1% osmium tetraoxyde and embedded in Epon 812. Thin sections coloured by uranyl acetate and lead citrate were observed with an Elmiskop I Siemens electron microscope.

Two important phenomena were observed in synovial tissue:

Specific patterns of each lipid storage disease,which are now well known.

In all the three metabolic diseases, hydroxyapatite-like crystals were found. They are characterized by their intramitochondrial localization, without any relation with cristae,an anarchic disposition and a mean size of 550 A.

Crystals may be found also free in the cytoplasm of synoviocytes Some micrographs suggest an evolution in four steps :

a. mitochondria with only a few microcrystals

b. mitochondria stuffed with these structures

c. disruption of mitochondria membranes

d. microcrystals appear free in the cytoplasm
Thermotropic lipid clustering in endoplasmic reticulum membranes of tetrahymena
Authors: Wunderlich F. , Kreutz W.
Published: June 2020

Freeze-etch electron microscopy detects lipid-protein-segregations in endoplasmic reticulum membranes directly within Tetrahymena cells. This manifests in the emergence of smooth areas on the fracture faces at ˜12°C upon cooling the cells from their suboptimal growth temperature of 18°C to 0°C (Figs.1,2). The membrane-intercalating-particles do not become laterally aggregated, but rather appear to be displaced perpendicularly to the membrane plane. Our previous studies using electron spin resonance, fluorescence spectroscopy, proton nuclear magnetic resonance, and differential thermal calorimetry have indicated that these lipid-protein-segregations are induced by a thermotropic lateral lipid clustering.

In order to support this suggestion we have now analyzed the thermotropism of the lipids gxtracted from microsomal membranes isolated from cells grov/n at 18°C by wide- and small-angle X-ray diffraction. Our data show that total lipids undergo a broad thermotropic fluid→ ordered phase separation (Figs. 3-5).
Ultrastructure and raman spectra changes caused by uncouplers of oxidative phosphorylation in artificial membranes
Authors: Pasquali-Ronchetti I. , Ghisellini M. , De Alojsio G. , Fini G.
Published: June 2020

Despite substantial evidence showed the existence of ultrastructural changes in uncoupled mitochondrial membranes, the precise mechanisms by which some chemicals uncouple oxidation from phosphorylation are still to be established.

In the present study evidence is presented that some uncoupling agents at the same concentrations (related to lipid content) that uncouple phosphorylation from oxidation in isolated mitochondria, alter the lipid phase of artificial phospholipid membranes.

Dipalmitoyl phosphatidyl choline dispersions in saline were studied by freeze-etching electron microscopy and Raman spectrometry and the changes caused by the uncoupling agents on the membrane structure were compared to those obtained by increasing the temperature of the system.
Types of cell contacts in different smooth muscles
Authors: Henderson Ruth M.
Published: June 2020

It is generally agreed that, where present, gap junctions or nexuses provide low-resistance pathways for cell-to-cell coupling of activity. Though these contacts were first described in smooth muscle and occur widely there, some types of smooth muscle contain few or no gap junctions, and many contain other types of contacts.

A variety of smooth muscles from several species was fixed with phosphate-buffered glutaraldehyde by intra-arterial perfusion or by immersion of small strips. Samples were prepared for electron microscopy by standard methods, using oriented embedding to view muscle in both longitudinal and cross sections.

Four types of cell contacts were identified in various smooth muscles, which have been previously recognized. 1) The gap junction or nexus appears with the usual double staining as a five-layered contact, often with adjacent clear areas of cytoplasm (Fig. 1).
Role of spectrin in membrane fusion and in shape change of human erythrocyte ghost
Authors: Hayashi Hideo , Hirai Yoshikazu , Penniston John T.
Published: June 2020

Spectrin is a membrane associated protein most of which properties have been tentatively elucidated. A main role of the protein has been assumed to give a supporting structure to inside of the membrane. As reported previously, however, the isolated spectrin molecule underwent self assemble to form such as fibrous, meshwork, dispersed or aggregated arrangements depending upon the buffer suspended and was suggested to play an active role in the membrane conformational changes. In this study, the role of spectrin and actin was examined in terms of the molecular arrangements on the erythrocyte membrane surface with correlation to the functional states of the ghosts.

Human erythrocyte ghosts were prepared from either freshly drawn or stocked bank blood by the method of Dodge et al with a slight modification as described before. Anti-spectrin antibody was raised against rabbit by injection of purified spectrin and partially purified.
Freeze-etch observations on the tight junctions of sertoli cells grown in organ culture with FSH
Authors: Meyer Rita , Posalaky Zoltan , Mcginley Dennis
Published: June 2020

The Sertoli cell tight junctional complexes have been shown to be the most important structural counterpart of the physiological blood-testis barrier. In freeze etch replicas they consist of extensive rows of intramembranous particles which are not only oriented parallel to one another, but to the myoid layer as well. Thus the occluding complex has both an internal and an overall orientation. However, this overall orientation to the myoid layer does not seem to be necessary to its barrier function. The 20 day old rat has extensive parallel tight junctions which are not oriented with respect to the myoid layer, and yet they are inpenetrable by lanthanum. The mechanism(s) for the control of Sertoli cell junction development and orientation has not been established, although such factors as the presence or absence of germ cells, and/or hormones, especially FSH have been implicated.
Preparation of the rigid layer (murein) of bacterial cell walls for high resolution electron microscopy
Authors: Formanek Helmut
Published: June 2020

I. Preparation of murein Murein or peptidoglycan is responsible for the rigidity of the cell- walls of almost all bacteria. It is a network of polysaccharide chains crosslinked by short peptide chains (Fig. 1 and 2). Based on the known primary structure and on X-ray and IR data a three dimensional model of peptidoglycan could be derived by theoretical considerations (Fig. 3). Peptidoglycan was prepared from deep frozen cells of the Gram negative bacterium Spirillum serpens.

The free aminogroups of peptidoglycan are brought to reaction with an excess of propylenesulfide in 1, 5 M K2HPO4, After removal of the excess of propylenesulfide by dialysis against water, the -SH groups incorporated into the peptidoglycan have been stained with equimolar amounts of the following heavy atom compounds: 2, 4, 6 Tri-acetoxymercuri-acet- aminotoluene or platinum blue Pt (CH3CONH)2. Since one free amino- group has been found per mesh of the murein network its periodicity has been marked with the single heavy atom molecules.
Reconstruction of the crystal-like particle arrangement within a bacterial membrane interlayer
Authors: Schiske P. , Reuber E. , Tesche B. , Wecke J. , Giesbrecht P.
Published: June 2020

Recently the existence of crystal-like particle arrangements in the interlayer between cell wall and cytoplasmic membrane in Gram-positive bacteria could be demonstrated for the first time, Results so far show the crystal-like regions as networks of interlinked ring-shaped units.

For further analysis of these structures, despite the limited extension of the ordered regions, digital image processing was attempted. For comparison of different preparation methods, specimens treated with freeze-etching and specimens treated with negative stain were used. The latter proved to be more amenable to reconstruction without separate correction of non-linear lattice distortion.

The micrographs were scanned along a 24-micron square grid with an effective collecting aperture of 50 micron diameter. 256 x 256 point Fourier transform was used. The filter mask was built from Gaussian peaks of equal shape and magnitude. Fourier transform of this shape in direct space gives an estimate of the area contributing to a single point of the reconstructed image.
Tubuloreticular structures in rubella virus-infected human fetuses
Authors: Kistler Gonzague S. , Groscurth Peter
Published: June 2020

Tubuloreticular structures (TRS) consisting of branching tubules of variable length and with a diameter of 18-30 nm have been described within dilated endoplasmic reticulum cisternae of endothelial and other cells in a variety of conditions. Thus, TRS have been observed in apparently normal human and animal cells, in cells of patients with auto-immune disease (e. g. systemic lupus erythematodes), with neoplasia (leukemias, carcinomas, sarcomas) as well as with a number of viral infections caused by both DNA or RNA viruses. Whereas earlier investigators regarded TRS as viral or virus-like in nature, it is now widely accepted that these structures represent focal proliferations of ER-membranes and that they reflect a cellular response to a broad range of stimuli. The biological significance of TRS has, however, not been resolved.

In rubella-infected human embryos and fetuses, vascular lesions are the most frequently observed light microscopical findings.
An investigation of experimental factors affecting the identification of enteroviruses by immunoelectron microscopy
Authors: Lee F. K. , Anderson N. , Doane F. W.
Published: June 2020

In 1973 Anderson and Doane described a rapid method for serotyping enteroviruses on the EM grid, using immunoelectron microscopy (IEM). By mixing an unknown viral isolate with individual or pooled enterovirus antisera, the resulting typing test could be read by electron microscopy, using the presence of virus-antibody aggregates as indication of a positive result. The reaction was found to be serotype specific when tested with a wide range of enteroviruses (coxsackie, polio, echo). These results were in contrast to those obtained earlier by Chaudhary et al., who observed cross-reactivity among enteroviruses using IEM. In light of the potential usefulness of this method for rapid virus diagnosis, a study was carried out on some of the experimental factors that might affect the reliability of enterovirus serotyping by IEM.

The most important factor in avoiding heterologous cross reactions was found to be the concentration of antiserum. As shown in Table I, when antisera were used at low dilutions they produced aggregation not only with the. homologous virus but also with the heterologous strains.
Permissivity of cerebellar explants for neurotropic viruses
Authors: Fournier J. G.
Published: June 2020

Cerebellar explants from 3 days old new born hamsters were infected with a viral suspension of 105 PFU/mI for measles virus and 106 for herpes (HSV 2) virus.

Under measles virus infection, nucleocapsids were observed after 10 days in the cytoplasm under the form of paracristalline structures (Fig. 1), sometimes associated with hidding of the cell surface. After 20 days nucleocapsids were also observed in the nucleus.

Under HSV infection cell lysis occured within 48 hours and was preceded by extensive production of nucleocapsids (Fig. 2). Maturation of the particles was visible in the nuclear envelope and the cell membranes.

In both infections the apparition of nucleocapsids was correlated with cellular changes, especially in the nucleus. Most alterations were observed in the chromatin, the nucleolus and perichromatin granules. The cell type, glial or neuronal, of the infection was analyzed.
Sendai virus maturation in actinomycin D pretreated and glutamine starved 37 RC and vero cells
Authors: Djaczenko Wiktor , Benedetto Arrigo , Stefania Zaniratti Maria
Published: June 2020

Actinomycin D (AMD) pretreatment (0. 5 μg/ml, 72h) causes surface glycoprotein accumulation in 37 RC and Vero cells (submitted for publication). On the other hand glutamine starvation in these cells does not inhibit the cell replication but reduces the cell adhesiveness to the plastic and glass substrates probably by depletion of glucosamine pool. In such metabolic conditions the modifications of plasma membrane flexibility could be expected. Since such a flexibility influences Sendai virus maturation we decided to study the replication of this virus in AMD pretreated and glutamine starved cells.

Three groups of 37 RC and Vero cells grown in monolayers, one untreated control, one AMD pretreated and one glutamine (G) starved were infected with Sendai virus. At 3. 5h and 24 h of infection corresponding cultures were fixed by: (a) classical methods, (b) TAPO techniqe and (c) ruthenium red method.
High resolution surface structure of foot-and-mouth disease virus
Authors: Breese S. S. , Bachrach H. L.
Published: June 2020

Models for the structure of foot-and-mouth disease virus (FMDV) have been proposed from chemical and physical measurements (Brown, et al., 1970; Talbot and Brown, 1972; Strohmaier and Adam, 1976) and from rotational image-enhancement electron microscopy (Breese, et al., 1965). In this report we examine the surface structure of FMDV particles by high resolution electron microscopy and compare it with that of particles in which the outermost capsid protein VP3(ca. 30, 000 daltons) has been split into smaller segments, two of which VP3aand VP3bhave molecular weights of about 15, 000 daltons (Bachrach, et al., 1975).

Highly purified and concentrated type A12, strain 119 FMDV (5 mg/ml) was prepared as previously described (Bachrach, et al., 1964) and stored at 4°C in 0. 2 M KC1-0. 5 M potassium phosphate buffer at pH 7. 5. For electron microscopy, 1. 0 ml samples of purified virus and trypsin-treated virus were dialyzed at 4°C against 0. 2 M NH4OAC at pH 7. 3, deposited onto carbonized formvar-coated copper screens and stained with phosphotungstic acid, pH 7. 3.
Electron investigations of rhabdovirus-like particles in mexican bean beetles and crickets
Authors: Adams J. R. , Tompkins G. J , Heimpel A. M. , Dougherty E.
Published: June 2020

As part of a continual search for potential pathogens of insects for use in biological control or on an integrated pest management program, two bacilliform virus-like particles (VLP) of similar morphology have been found in the Mexican bean beetle Epilachna varivestis Mulsant and the house cricket, Acheta domesticus (L. ).

Tissues of diseased larvae and adults of E. varivestis and all developmental stages of A. domesticus were fixed according to procedures previously described. While the bean beetles displayed no external symptoms, the diseased crickets displayed a twitching and shaking of the metathoracic legs and a lowered rate of activity.

Examinations of larvae and adult Mexican bean beetles collected in the field in 1976 and 1977 in Maryland and field collected specimens brought into the lab in the fall and reared through several generations revealed that specimens from each collection contained vesicles in the cytoplasm of the midgut filled with hundreds of these VLP's which were enveloped and measured approximately 16-25 nm x 55-110 nm, the shorter VLP's generally having the greater width (Fig. 1).
Canadian bunyavirus morphogenesis in arctic mosquitoes
Authors: Wong K. K. , McLean D. M.
Published: June 2020

Morphogenesis of two Canadian Bunyavirus isolates, the snowshoe háre subtype of California encephalitis (CE) virus, and Northway (NOR) virus, has been studied in salivary glands of wild-caught Aedes communis mosquitoes from the Western Canadian Arctic. An Australian flavivirus, Murray Valley encephalitis (MVE) virus has also been studied in these mosquitoes. Female mosquitoes were inoculated intrathoracically with 100-1000 mouse LD50 CE or MVE virus or 300 plaque forming units NOR virus. Mosquitoes were incubated at 13°C for extended periods, after which salivary glands were dissected away from mosquitoe thoraces. With the proboscis attached, glands were fixed with glutaraldehyde and postfixed with osmic acid before embedding in Epon 812. Thin sections of salivary glands were examined, using a Philips EM-300 electron microscope. Infectivity titrations of salivary glands or thoraces of the same batch of mosquitoes were performed whenever possible.
Surface structure of the bacteriophage λ head: location of the gpD
Authors: Wurtz M. , Imber R. , Tosi M. , Hohn T.
Published: June 2020

The mature bacteriophage λ head contains two major proteins: gene products E and D (gpE and gpD). These proteins are arranged in a composite (gpE/gpD ratio = 1/1) T=7 icosahedral surface lattice.

In previous studies using tubular head related forms, “polyheads”, we had proposed models for head maturation and structure. But with the methods used, it was not possible to localize unambiguously the position of the gpD clusters added during the last steps of the head maturation. New experiments are performed to choose between the two different models previously proposed.

In a first step we have analysed with optical filtration some structures obtained after self-assembly of guanidine hydrochloride dissociated heads. One sided preferentially stained polyhead (Fig. 1) or monolayer (sheets) (Fig. 2) show the triangular shape clusters which could be the gpD trimers. We were able to get some improvement of the resolution of normal polyhead images by removal of associated debris with a mild treatment of citraconyl anhydride (10 mg/mg of polyhead) before preparing the specimen for the conventional electron microscope (Fig. 3) or the scanning transmission electron microscope (Fig. 4).
Ultrastructure of diplodia maydis infection process in zea mays
Authors: Murphy Judith A. , Thompson Mary R. , Pappelis A. J.
Published: June 2020

Diplodia maydis(Schw.)Lev.is one of the major pathogens causing stalk rot of corn (Zea mays L), a complex disease resulting in an annual loss of more than one billion bushels of corn. Many studies concerning resistance or susceptibility of corn to D. maydis have been reported but none at the ultrastructure level. Because of the importance of D. maydis as a pathogen, it was the purpose of this study to investigate the host- parasite relationship, to elucidate the penetration phenomenon at the ultrastructural level, and to study any changes apparent in the host cell wall and in the fungal cell during the infection process.

Samples for TEM were fixed in cold 3% buffered glutaraldehyde, buffer washed 3-6 times and post-fixed in 1% OSO4. Samples were then dehydrated through a graded EtOH series and propylene oxide and embedded in Epon-Araldite. Sections were cut on a Reichert 0m U2,stained with uranyl acetate/lead citrate or dipotassium tetramethyl osmate and examined in an Hitachi HU11AB at 50 KV.
Silicalemma membrane pattern and valve formation of a centric diatom
Authors: Schulz Dieter
Published: June 2020

From scanning electron micrographs we know the morphology of the mature frustule of Thalassiosira eccentrica (Ehrenb.) Cleve. The valve surface is build up of rounded areolae in more or less hexagonal pattern with pores being also hexagonal arranged. The authors (1) also documented micrographs showing great variation of this pattern in the same species, for example, with rows of silica running radially from the centre of the valve to the valve margins. Our investigations, dealing with the pattern formation of the diatom wall can possibly explain this variation in a simple manner. Using the freeze-etching technique we have been able to demonstrate a significant change in the surface pattern of silicalem-ma (Sil) membranes during valve formation. Fig. 1 shows the PF-face of the inner SiL membrane at a young stage of valve formation short after the completion of cleavage in T. eccentrica. Small knob-like structures (arrowheads in fig 1) with a diameter of about 50 nm intermingled with 100Å particles seem to alternate randomly with smooth membrane areas.
Membrane biogenesis on isolated protoplasma surface
Authors: Salyaev R. K. , Chernyshov V. I. , Kuzevanov V. Ya.
Published: June 2020

A number of papers show the formation of a new membrane on the surface of protoplasm run out after cutting of Characeae alga cells in a medium containing bivalent cations.

The drops of isolated protoplasm were prepared by cutting of Nitella cells in a special decompression chamber under the conditions of turgor pressure compensation. The drops were transferred into agar microcapsules (Fig. 1), the preparation of which was described in detail earlier (Salyaev, 1968). The walls of agar microcapsule were transparrent therefore protoplasm drops were clearly observed in a light microscope (Fig. II). All other operations such as fixation, dehydratation and embedding in epoxy resins were made in agar microcapsule.

Electron microscopic investigation revealed that the method of a drop preparation preserved all components of a protoplasmic ultrastructure: endoplasmic reticulum, ribosomes, mitochondria etc., the hyaloplasm being rather hydrated (Fig. III). The surface of isolated protoplasmic drop was shown to be a typical membrane 80-90Åthick (Fig. IV).
Architectonics of structural elements of photosynthetic apparatus
Authors: Shiryaev A. I. , Reingard T. A. , Ostrovskaya L. K.
Published: June 2020

Utilization of electron microscopy possessing a high resolution enriched the picture of macromolecular organization of chloroplasts, their individual structural elements and molecular complexes. Great possibilities have been opened in this direction with the development of negative staining method and other most recent ones allowing to study macromolecular topography of photosynthetic membranes and producing out of them grana thylakoids and stroma thylakoids. we succeeded in isolation of stroma thylakoids by means of developing the conditions of fragmentation of isolated chloroplasts. They differed radically from grana thylakoids in form and size. The analysis of submicroscopic and macromolecular organization of thylakoids was carried out by the method of negative staining (2% PTA) and ultrathin sections. Grana thylakoids (Fig. 1) isolated from chloroplasts with the aid of high pressure (150 atm) were observed in the form of rounded membranes with the diameter about 0. 5 Mm and had the particles of coupling factor on their surface (about 100 Å in diameter).
In vitro and in vivo polysaccharides assembly: ultrastructural and cytochemical study of growing plant cell wall components.
Authors: Reis D. , Vian B. , Roland J. C.
Published: June 2020

Wall morphogenesis in higher plants is a problem still open to controversy. Until now the possibility of a transmembrane control and the involvement of microtubules were mostly envisaged. Self-assembly processes have been observed in the case of walls of Chlamydomonas and bacteria. Spontaneous gelling interactions between xanthan and galactomannan from Ceratonia have been analyzed very recently. The present work provides indications that some processes of spontaneous aggregation could occur in higher plants during the formation and expansion of cell wall.

Observations were performed on hypocotyl of mung bean (Phaseolus aureus) for which growth characteristics and wall composition have been previously defined.

In situ, the walls of actively growing cells (primary walls) show an ordered three-dimensional organization (fig. 1). The wall is typically polylamellate with multifibrillar layers alternately transverse and longitudinal. Between these layers intermediate strata exist in which the orientation of microfibrils progressively rotates. Thus a progressive change in the morphogenetic activity occurs.
Fine structure of the fish chloride cell associated with both acute and chronic exposure to mercury
Authors: Koepp Stephen J. , Dorato NAncy C.
Published: June 2020

Prior cytopathologic studies have demonstrated the sensitivity of fish respiratory and transporting epithelia to mercurials. Despite a well-documented role in extrarenal osmoregulation, the specific involvement of the teleost chloride cell in mercurialism has not been reported. This paper describes the response of this primary filament cell versus acute and chronic exposure to mercuric chloride. The estuarine fish (Fundulus heteroclitus) was used as the target organism. Locally-collected male mummichogs (3. 5-4. 5 g) were acclimated in the laboratory two weeks prior to use. For acute contaminations fish were incubated in artificial seawater containing one of three concentrations of mercury (0. 25, 0. 75 and 1. 50 mg/1) at 20 C and 20 o/oo salinity. In a similar manner other fish were exposed for 30 days to an environmental concentration of toxicant (0. 05 mg/1). Gill tissues of survivors at 12, 36 and 96 hours (acute) and 30 days (chronic) plus controls were fixed for three hours in cold 4% phosphate-buffered glutaraldehyde, postfixed in 1% osmium tetroxide and subsequently embedded in Epon 812.
Mucosubstances of the granulocytes studied by means of electron microscopic radioautography and X-ray microanalysis
Authors: Murata F. , Yoshida K. , Ohno S. , Nagata T.
Published: June 2020

As a series of histochemical studies on the mucosubstances of the granulocytes in this laboratory, the results obtained by electron microscopic radioautography and X-ray microanalysis have been reported.

The femur bone marrows of adult rabbits weighing 1. 0-1. 5kg were diced into small pieces and incubated for 10, 30 and 60 minutes in Eagle's MEM supplemented with 10 % bovine serum, containing radioactive carrier free sulfuric acid at a concentration of lmCi/ml. They were fixed doubly in glutaraldehyde buffered with 0. 1 M phosphate buffer (pH 7. 2) and osmium tetroxide buffered with 0. 1 M phosphate buffer(pH 7. 2), dehydrated through a graded series of ethanol and acetone and embedded in Epon. Ultrathin sections were cut with an LKB ultrotome and radioautographed with Sakura NR-H2 emulsion by wire loop method, exposed for 127-203 days, developed with phenidone developer after gold latensification, stained with lead citrate and observed in Hitachi HS-9 electron microscope.
The cytoskeleton of human platelets at rest and after spreading: whole mounts viewed at 200 KV correlated with negatively stained specimens examined at 50 KV
Authors: Nachmias V. T. , Sullender J. S.
Published: June 2020

New morphological approaches are needed to determine what changes take place in the cytoskeleton of platelets during activation by spreading or by agonists, for little information can be gained from thin sections alone. For whole mount study, we fixed platelets in plasma at 37°C very briefly with 0. 1% or 2. 5% formaldehyde freshly prepared from paraformaldehyde. We deposited the platelets on carbon-substrated grids, lysed them with 1% triton X 100, critically point dried them and examined them without staining in a JE0L JEM 200A electron microscope at 200 KV. These specimens were compared with unfixed platelets lysed with 1% triton-X 100 and subsequently negatively stained with 2% uranyl acetate and examined at 50 KV.

Discoid, resting platelets fixed in suspension and viewed as whole mounts contained a dense interior which was removed to a variable degree by the lytic agent. In favorable specimens, the interior was observed to be made up of globular masses which could be roughly divided into two size classes
Ultrastructure of pulmonary microvasculature in acute endotoxemia
Authors: Gerrity R. G. , Richardson M.
Published: June 2020

Dogs were injected intravenously with E_. coli endotoxin (2 mg/kg), and lung samples were taken at 15 min., 1 hr. and 24 hrs. At 15 min., occlusion of pulmonary capillaries by degranulating platelets and polymorphonuclear leukocytes (PML) was evident (Fig. 1). Capillary endothelium was intact but endothelial damage in small arteries and arterioles, accompanied by intraalveolar hemorrhage, was frequent (Fig. 2). Sloughing of the surfactant layer from alveolar epithelium was evident (Fig. 1). At 1 hr., platelet-PML plugs were no longer seen in capillaries, the endothelium of which was often vacuolated (Fig. 3). Interstitial edema and destruction of alveolar epithelium were seen, and type II cells had discharged their granules into the alveoli (Fig. 4). At 24 hr. phagocytic PML's were frequent in peripheral alveoli, while centrally, alveoli and vessels were packed with fibrin thrombi and PML's (Fig. 5). In similar dogs rendered thrombocytopenic with anti-platelet serum, lung ultrastructure was similar to that of controls, although PML's were more frequently seen in capillaries in the former (Fig. 6).
The developing nephron of the sea lamprey during metamorphosis
Authors: Ooi E. C. , Youson J. H.
Published: June 2020

The definitive opisthonephric kidneys of lamprey each contains a single renal corpuscle with multiple nephric capsules surrounding a single compound glomerulus (glomus), which extends the length of the kidney. Each nephric capsule possesses a visceral layer of podocytes and a parietal layer continuous with the tubular epithelium. The development of these renal corpuscles and proximal portions of the tubules in the sea lamprey, Petromyzon marinus L., during metamorphosis was studied using electron microscopy.

The nephron rudiments of the definitive opisthonephros arose as condensations of undifferentiated cell mass (Fig. 1) closely associated with the peritoneum. The differentiation of nephron rudiments along the entire nephrogenic cord was initiated synchronously at the onset of metamorphosis resulting in a series of rudimentary nephron units (RNU) which formed connections with the archinephric duct. The branching of RNU gave rise to secondary and tertiary rudimentary nephrons which radiated semicircularly from the original point of attachment to the peritoneum.