bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electron microscopy of a dna helix destabilizing protein crystal (gp32*i)
Authors: Chiu Wah , Hosoda Junko 
Published: June 2020

Gp 32 is a protein coded by gene 32 in bacteriophage T4. It is essential for DNA replication, recombination and repair. Gp32*I with molecular weight of 27,000 was obtained by proteolytic removal of 8000-dalton peptide from COOH-terminal of gp32 (Hosoda et al. to be published). It is a stronger helix destabilizer than gp32, and has been found to be able to replace gp32 in constructing an in vitro DNA replication apparatus, which is active in the leading strand synthesis.Thin gp32*I crystal was formed under a low salt condition in the absence of glycerol. Figure 1 shows a typical image of the crystal embedded in 1% glucose taken at low magnification. The optical diffractogram in the insert confirms the crystallinity, though no visible feature is seen in the micrograph due to the low magnification power. By using the tungsten shadowing technique, the thickness of the crystal was measured, along with polystyrene latex spheres as a standard, to be between 85 to 400 Å.
Ultracytochemical studies on effects of cortisone acetate on the lysosomal system of Yoshida ascites sarcoma cells
Authors: Abe Shyogo , Ogawa Kazuo 
Published: June 2020

Effects of cortisone acetate (CA) on the lysosomal system were investigated in Yoshida ascites sarcoma cells maintained by serial intraperitoneal passage at 6-day intervals in the peritoneal cavity of adult male Donryu rats both in vivo and in vitro under the light and the regular (75-100KV) as well as the high voltage (1,000KV) electron microscopes (EM).In in vivo experiments ascites sarcoma cells taken from CA-treated rats half an hour to 8 hours after intravenous injection of CA (24mg/kg b. w.) suspended in 0. 5ml of saline were investigated. In control rats only saline was injected. Routine morphological observation as well as the demonstration of acid phosphatase (ACPase) activity was performed. Light microscopic observation revealed an obvious increase in number of lysosomes having strongly positive ACPase activity in cells collected 2 to 4 hours after CA injection, but 8 hours after no marked differences were observed between cells taken from the control and CA-treated rats.
An attempt to modify the configurational states of mitochondria from the ependyma of the choroid plexus in vivo.
Authors: Rydzynski Konrad 
Published: June 2020

It was shown in vitro-on isolated mitochondria as well as on mitochondria from Ehrlich Ascites Tumor Cells-that adding of 2,4-dinitrophe- nol /DNP/ to the incubation medium leads to characteristic structural changes coinciding with adequate respiratory states. The aim of this study is to investigate, at the ultrastructural level, to what extent it would be possible to modify the configurational states in vivo on the model of the choroid plexus of rats' brain lateral ventricles. It produces the cerebrospinal fluid /CSP/, and is responsible for its composition through the active secretion of certain ions. ATP is indispensable in the process. It has been proved that DNP penetrates the plexus' epithelium and probably inhibits the active processes there by means of uncoupling the oxidative phosphorylation in the mitochondria.Material and MethodsWistar rats, weighed 280-330 g,were anesthetized with Nembutal /30 mg/kg i.p./ and fortal /1 mg/kg i.m./, then placed in stereotactic apparatus for ventriculo-cisternal perfusion.
The effect of nocodazole on microtubule formation and histamine release from mast cells
Authors: Holm Nielsen Ellen , Johansen Torben 
Published: June 2020

In exocrine and endocrine gland cells and in nerve cells microtubules (MT) seem to be associated with intracellular transport or secretory activity, although this association has been questioned by contradictory results. A role of MT in secretion of histamine from mast cells is not established. Experiments with drugs, which inhibit either polymerization or depolymerization of MT as colchicine and D2O so far have led to contradictory conclusions. The reason for this may be that the effect of colchicine and D2O in the intact cell is not well defined. This study compares the number and distribution of MT in untreated and in compound 48/80 treated mast cells, and examines the effect of a new synthetical MT inhibitor, Nocodazole, on histamine release and on MT in mast cells.Mixed peritoneal cells from male Sprague-Dawley rats, 400-500 g, were obtained as previously described and used for the TEM experiments.
A scanning electron microscope study of lectin receptors on neuroblastoma cells
Authors: Maher P. , Molday R.S. 
Published: June 2020

The organization and redistribution of concanavalin A (Con A), Ricinus communis agglutinin I (RCA I) and wheat germ agglutinin (WGA) receptors on mouse neuroblastoma cells was analyzed using lectins conjugated to fluorescent polymeric microspheres as visual markers for scanning electron microscopy (SEM) and fluorescent light microscopys. Results indicate that all three lectins are internalized by these cells but the patterns of redistribution for Con A differ from those of RCA I and WGA.Labeling of prefixed undifferentiated and differentiated neuroblastoma cells indicated that Con A, WGA and RCA I receptors were densely and uniformly distributed over the cell surface and neurites. Cells treated with lectin for 5-10 minutes at 37°C, washed free of excess reagent and maintained for up to 15 minutes in buffer exhibited uniform labeling patterns.
Ultrastructure of immunoblastic sarcoma as observed by freeze-fracturing
Authors: Nakai Ei-Ichi , Asamoto Hitoshi , Furuta Mutsuhiro , Nishiura Mitsugu 
Published: June 2020

Malignant tumor cells have an enhanced rate of cell division and of metabolic activities of cells. We studied IgG positive immunoblastic sarcoma cells by means of freeze-fracturing and found significant structural differences between these tumor cells and control B-cells.Lymphnodes infiltrated with sarcoma cells were dissected from the cervical areas of two patients. The sarcoma cell suspension was obtained from these lymphnodes. Sarcoma cells had fine granules stained with PAS and mothyl green pyronin in cytoplasma. Most of sarcoma cells were positive fluorescent (SIgG bearing). Alpha-naphthyl-acetate-esterase test was negative or false positive. Single cell suspension of lymphnodes was obtained from patients of non-lymphatic diseases. EAC rosette forming cells and adherent cells to nylon column fiber were used as control B-cells. The pellet of sarcoma cells and control B-cells were fixed with 2. 5% glutaraldehyde solution. Freeze-fracture was done as described previously. Under the electron microscope, EAC rosette forming cells were selected as control B-cells.
High resolution imaging of the rigid layer of bacterial cell walls at liquid helium temperatures
Authors: Fox F. , Knapek E. , Weyl R. 
Published: June 2020

Construction and working capability of a superconducting lens system installed in a 400 kV electron microscope have already been described in. The main features of the imaging possibilities are shown in Fig. 1 As a consequence of cooling the object to liquid helium temperature and the ideal cryovacuum the lens system is especially suited for investigating biological specimens (absence of contamination and ion etching)We tried to obtain information on the structure of murein or peptido- glycan, the rigid layer of bacterial cell walls. Details on the preparation of the specimens, which are decorated with heavy atoms (3 Hg or Pt) are given elsewhere in these proceedings. Graphite oxide was normally used as a carrier foil with little contrast. The images taken from the murein in most cases showed a large number of dark spots which probably are contaminations dating from the preparation of the specimens (Fig. 2).
Sensitivity of scanning electron microscopy for the detection of mycoplasma contamination
Authors: Quinn Patricia A. , Ho Tai Y. 
Published: June 2020

Mycoplasma contamination of cell cultures causes a serious problem in the interpretation of experimental data. These organisms interfere with cell metabolism, induce heritable chromosome abnormalities, alter the antigenicity and function of the cell membrane, contaminate virus preparations and make the interpretation of cell surface structures difficult. Mycoplasmas can be isolated by direct culture. However certain strains will not grow in cell-free media. Indirect methods based on the staining of cultures and the assay of uridine phosphorylase enzyme activity require large numbers of organisms to yield positive results. With SEM, individual particles or clusters on only a few cells in the culture can be visualized.The actual sensitivity of SEM as a detection method is difficult to evaluate since many mycoplasmas grow in aggregates and reproduce by budding or the breaking apart of filaments as in Fig. 1.
Structural aspects of osmoregulation in porphyra
Authors: Wiencke C. , Lauchli A. 
Published: June 2020

Osmoregulatory mechanisms in algae were investigated mainly from a physiological point of view (KAUSS 1977, HELLEBUST 1976). In Porphyra two osmotic agents, i. e. floridoside/isofloridoside (KAUSS 1968) and certain ions, such as K+ and Na+(EPPLEY et al. 1960) are considered for osmotic balance. Accumulations of ions (particularly Na+) in the cytoplasm during osmotic adaptation is improbable, because the activity of enzymes is generally inhibited by high ionic concentrations (FLOWERS et al. 1977).The cellular organization of Porphyra was studied with special emphasis on the development of the vacuolar system under different hyperosmotic conditions. Porphyra was cultivated at various strengths of the culture medium ASP 12 (PROVASOLI 1961) ranging from normal to 6 times concentrated (6x) culture medium. Por electron microscopy freeze fracturing was used (specimens fixed in 2% glutaraldehyde and incubated in 30% glycerol, preparation in a BALZERS BA 360 M apparatus), because chemical fixation gave poor results.
Ultrastructure of mimosa leaflet and pulvinule
Authors: Stein-Margolina V. A. 
Published: June 2020

The ultrastructure of leaflet and tertiary pulvini (pulvinule) of the sensitive plant, Mimosa pudica L., as well as the distribution of ATPase were studied before and after stimulation.There are two zones in the majority of upper epidermis cells of the leaflet (Fig. 1). The upper zone contains a thin layer of cytoplasma, a large central vacuole and much tannin. The lower zone of these cells is electron-transparent and has a lens-like shape. It is filled with fibrillar-foamy material (Fig. 2). “The foam” fibrills are 30-100 Å in diameter. “The foam” is stained with ruthenium red and is supposed to be a mucilaginous inner (lower) wall of the epidermal cell. The cells of the lower epidermis of the leaflet and the pulvinule epidermis do not contain “the foam”. The lens-shaped foamy material might focus light, promote its reception and transfer the light stimuli within the leaflets and pulvini, thus regulating the heliotropic and nyctinastic position of the leaf itself.
Fine structure of the vitteline cells in the cestode Proteocephalus longicollis (proteocephalidea)
Authors: Swiderski Z. , Eklu-natey R. D. , Subilia L. , Huggel H. 
Published: June 2020

The mature vitelline cells of Proteocephalus longicollis (Zeder, 1800) are ovoid or spherical and measure about 30μm in diameter. They represent the holocrine type of secretory cells.The spherical nuclei, about 10μm in diameter, are localized in the central part of the cell. They contain more or less prominent nucleoli enclosed in the moderately electrondense nucleoplasm (Fig. 1).The cytoplasm (Fig. 2, 3, 4) is packed with numerous shell globules of heterogenous type, large lipid droplets, and a few glycogen islands composed mainly of α-glycogen rosettes.The remaining granular cytoplasmic matrix (Fig. 3, 4) contains: (a) numerous polysomes, (b) cysternae of granular endoplasmic reticulum, (c) several mitochondria, and (d) extended Golgi regions, composed of vesicles of different sizes and density.The extensive development of granular endoplasmic reticulum (GER) and Golgi complexes indicates high secretory activity of these cells. Both Golgi and GER are evidently engaged in shell globule formation and are considered therefore to function as the shell-protein producing units
A dense cell in the epithelium of the gill lamellae of the fresh-water brook trout, salvelinus fontinalis
Authors: Morrison C. M. 
Published: June 2020

Introduction Unspecialized, dark, chloride and mucous cells have been described in the epithelium of the gill lamellae of Salmo gairdneri and the chloride cell of fresh-water Salvelinus fontinalis has been described. In the course of other studies we found another cell type in the epithelium of fresh-water Salvelinus fontinalis, which is described in the following account.Methods Six fresh-water brook trout, and two adapted to salt-water were killed by a blow on the head, and gill filaments were removed, fixed in Karnovsky's fixative then osmium tetroxide, dehydrated in acetone and embedded in epoxy resin. Thin sections for electron microscopy were stained with 25% uranyl acetate in methanol and lead citrate.Observations The epithelial cells described in Salmo gairdneri were also found in Salvelinus fontinalis, but another type was seen in fresh-water Salvelinus fontinalis. These cells were often as large as chloride cells and had a similar shape, but the cytoplasm and basal nucleus were usually darker, round vesicles were present in the apical cytoplasm, and large membrane-bound bodies were often present in the basal cytoplasm (Fig. 1).
Association of microtubules and microfilaments with mucin granules in tracheal goblet cells—their possible role in exocytosis
Authors: Adler Kenneth B. , Brody Arnold R. , Craighead John E. 
Published: June 2020

Accumulating experimental evidence suggests that microtubules (MT) and microfilaments (MF) play a major role in the translocation of intracellular organelles. MF are composed of the contractile protein actin; several groups of investigators (Bikle, D. et al: Protoplasma 61:322, 1966; Van Oberghen, E. et al: Diabetes 24:892, 1975) have speculated that these structures provide the force which propels intracellular granules along a pathway delineated by a network of MT. We carried out an ultrastructural investigation of the possible role of MT and MF in the intracellular transport and exocytosis of membrane-bound mucin granules by goblet cells.Tracheal tissue was excised from newborn female piglets and immersed in 4% gluteraldehyde in a buffer at pH 6. 9 of 1mM GTP, 1mM MgSO4, l00mM PIPES, and 2mM EGTA, a fixative designed to improve visualization of MT (Luftig, R. B. et al: J. Histochem. Cytochem. 25:l75, 1977).
A simple method for ultrastructural visualization of cytoplasmic microfilament bundles (mfb) in rat hepatocytes
Authors: Yokota S. , Fahimi H.D. 
Published: June 2020

Microfilaments (MF) are present in a variety of animal and plant cells, and there is substantial evidence that they are involved in cellular motility and contractility (1). Although MF's were first discovered by electron microscopy (EM), they are not distinctly visible in routine EM preparations of whole tissue. In partially disrupted hepatocytes and in isolated bile canaliculi, however, the MF's are prominently contrasted with the uranyl acetate en bloc treatment (2). We now report our observations on the treatment of glutaraldehyde- (GA) fixed rat liver with various detergents. This procedure, followed by uranyl staining, increases markedly the electron density and the contrast of MFB's in tissue sections.Materials and Methods: Livers of adult rats were fixed by perfusion with 2.5% purified GA in 0.1M Na-cacodylate buffer, pH 7.2, and 0.05% CaCl2 for 10 min. 50-μm chopper sections were treated with 0.1-1% Triton X-100 or sodium deoxycholate (DOC) for 1 h at 25°C, rinsed briefly with the buffer, and then postfixed in 2% aqueous OsO4 for 60 min. at 4°C. This was followed by en bloc staining for 60 min. with 1% uranyl acetate in 0.2M Tris-maleate buffer, pH 5.2, and embedding in Epon. Ultrathin sections were stained with uranyl acetate and lead citrate. In control preparations the detergent treatment was omitted, but all other procedures were identical.
A scanning electron microscopic study on dissolving process of cholesterol gallstones by chenodeoxycholic acid (CDCA)
Authors: Kanetaka T. , Cho M. , Kawamura S. , Sado T. , Hara K. 
Published: June 2020

The authors have investigated the dissolution process of human cholesterol gallstones using a scanning electron microscope(SEM). This study was carried out by comparing control gallstones incubated in beagle bile with gallstones obtained from patients who were treated with chenodeoxycholic acid(CDCA).The cholesterol gallstones for this study were obtained from 14 patients. Three control patients were treated without CDCA and eleven patients were treated with CDCA 300-600 mg/day for periods ranging from four to twenty five months. It was confirmed through chemical analysis that these gallstones contained more than 80% cholesterol in both the outer surface and the core.The specimen were obtained from the outer surface and the core of the gallstones. Each specimen was attached to alminum sheet and coated with carbon to 100Å thickness. The SEM observation was made by Hitachi S-550 with 20 kV acceleration voltage and with 60-20, 000X magnification.
Investigations into the mechanism of hormone release by rat steroid-producing cells
Authors: Nussdorfer G. G. , Neri G. , Robba C. , Mazzocchi G. , Bortolussi M. 
Published: June 2020

Biochemical evidence suggests that an exocytotic mechanism underlies hormone release in steroid producing cells. However, the demonstration of secretory granules has been so far elusive, probably owing to the fact that in steroid-producing cells there is little or no appreciable intracellular storage of hormonal products. Since numerous reports indicate that microtubules play a permissive role in exocytotic mechanisms, we devised to investigate the effects of vinblastine (an antimicrotubular agent) on rat lutein and adrenocortical cells.Fifteen adult male rats were divided into 3 experimental groups. Group 1 served as a control; group 2 was given an ip. injection of 25mg/kg of vinblastine (Velban, Lilly) 2 hours before sacrifice; group 3 was treated as group 2, but in addition received an ip. injection of 20IU/kg of ACTH 1 hour before sacrifice. An analogous experiment was performed using fifteen pseudogravid prepubertal rats, except that group 3 received 250 IU of HCG 1 hour before sacrifice. The corticosterone and progesterone concentrations in male and female rats, respectively, were determined by radioimmunological methods, in both the peripheral plasma and the homogenates of the right adrenal or ovary.
Effects of renovascular hypertension on rat adrenal zona glomerulosa
Authors: Mazzocchi G. , Rebuffat P. , Robba C. , Vassanelli P. , Nussdorfer G. G. 
Published: June 2020

It is well known that the rat adrenal zona glomerulosa steroidogenic activity is controlled by the renin-angiotensin system. The ultrastructural changes in the rat zona glomerulosa cells induced by renovascular hypertension were described previously, but as far as we are aware no correlated biochemical and morphometric investigations were performed.Twenty adult male albino rats were divided into 2 experimental groups. One group was subjected to restriction of blood flow to the left kidney by the application of a silver clip about the left renal artery. The other group was sham-operated and served as a control. Renovascular hypertension developed in about 10 days: sistolic blood pressure averaged 165 ± 6. 4 mmHg, whereas it was about 110 ± 3. 8 mmHg in the control animals. The hypertensive and control rats were sacrificed 20 days after the operation. The blood was collected and plasma renin activity was determined by radioimmunological methods. The aldosterone concentration was radioimmunologically assayed both in the plasma and in the homogenate of the left capsular adrenal gland.
Healing in the central nervous system of mammals
Authors: Ashhurst Doreen E. , Berry M. 
Published: June 2020

Regeneration of axons in the mammalian CNS appears to be limited to a small group of unmyelinated fibres; the majority of axons are unable to grow across a lesion. Despite much work, the mechanism by which the growth of these axons is inhibited, is not understood. A mature, fully healed lesion is filled by collagenous tissue and bordered by the foot processes of astrocytes. Little is known of the early stages in the healing of a lesion, and since it was considered that the sequence of events in the days immediately following injury might be of special significance in determining whether the regenerating axons cross the lesion, this study was initiated.Lesions made with a knife were placed stereotactically in the left cerebral hemisphere of 30-day-old Wistar rats of either sex. After periods of 1, 2, 4, 8, 12 and 30 days, the brains were perfused first with 20% and then 5% glutaraldehyde in 0. 1M phosphate buffer, pH 7. 2 containing 0. 05M sucrose.
Undecagold labeling of tRNA
Authors: Hainfeld James F. , Alford Kyra M. , Sprinzl Mathias , Mandiyan Valsan , Tumminia Santa J. , Boublik Miloslav 
Published: June 2020

The undecagold (Au11) cluster was used to covalently label tRNA molecules at two specific ribonucleotides, one at position 75, and one at position 32 near the anticodon loop. Two different Au11 derivatives were used, one with a monomaleimide and one with a monoiodacetamide to effect efficient reactions.The first tRNA labeled was yeast tRNAphe which had a 2-thiocytidine (s2C) enzymatically introduced at position 75. This was found to react with the iodoacetamide-Aun derivative (Fig. 1) but not the maleimide-Aun (Fig. 2). Reaction conditions were 37° for 16 hours. Addition of dimethylformamide (DMF) up to 70% made no improvement in the labeling yield. A high resolution scanning transmission electron micrograph (STEM) taken using the darkfield elastically scattered electrons is shown in Fig. 3.
Ultrastructural evaluation of the effects induced by a macrolide antibiotic (LY281389) on L6 muscle cells in vitro
Authors: Horn J. W. , White S. L. , Laska D. A. , Buening M. K. , Novilla M. N. , Jensen C. B. , Hoover D. M. 
Published: June 2020

Toxic doses of LY281389 (9-N(n-propyl)erythromycylamine), a cationic amphophilic macrolide antibiotic, induce a generalized cytoplasmic vacuolar change in tissues of rats and dogs. The present in vitro study using L6 cells (a line derived from neoplastic skeletal muscle) was done to evaluate sequentially early cytologic changes.The L6 cells seeded on tissue culture plates were allowed to grow to a uniform density. The culture medium was then replaced with control medium or medium containing 0.25 mg/ml LY281389 for exposures of 0.5, 2, 6, 12, 24, or 48 hours. The L6 cells were then fixed for 1-hour in modified Karnovsky's solution (pH 7.2), rinsed with 0.1 M sodium cacodylate buffer (pH 7.2) and postfixed for an additional hour in 2% osmium tetroxide (pH 7.2). Following a second buffer rinse, the L6 cells were dehydrated in graded ethanol solutions. The cells on each plate were embedded with epoxy resin (EPON 812), selected areas were scribed out and re-embedded for orientation. Ultrathin sections (silver to gold color interference range) were mounted on copper 200 mesh grids, counterstained, and examined using a Philips EM410LS electron microscope at 60kV.