bluuebunny/crossref_metadata_2025_split huggingface dataset:
Redistribution of Membranes during Conidiogeneses and Nuclear Development in Verticillium Dahliae
Authors: Mayfield J. E. , Tolmsoff W. J. , Wheeler M. H. 
Published: June 2020

Verticil1ium dahliaeis an asexual fungus that produces unicellular, mononucleate conidia as its primary means of reproduction. For conidial formation, specialized hyphal cells convert into verticillate conidiophores, bearing tapered phialides. A conidium develops from the phialide as a protrusion through the terminal pore. Each phialide has a single nucleus that divides repeatedly during the sequential production of numerous conidia. Nuclear material has been found to migrate into developing conidia just before their separation from the phialide tip (1). The present report suggests a possible mechanism for nuclear division and migration.The ultrastructure of phialides and developing conidia ofV. dahliaewas examined from a narrow zone 5 mm behind the periphery of colonies grown on potato-carrot-dextrose agar. Cells were fixed with 3l glutaraldehyde in cacodylate buffer (pH 6.8) at room temperature, postfixed in cold 2% OsO4in the same buffer, and thin sections were counter stained with 2% uranyl acetate and lead citrate.
Cytochemical Studies of Biogenic Amines
Authors: Wood Joe 
Published: June 2020

The electron microscopic localization of biogenic amine neurotransmitters can provide for a definitive approach to the study of these chemical agents in relation to the neuroanatomical substrate of the nervous system. Therefore, if one can specifically identify a neurotransmitter within certain ultrastructural nervous system components then a better understanding is developed of the chemico-morphologic functional relationships. Thus one can develop further the concepts of the chemical interactions within the nervous system.The localization technique must be chemically specific for a particular compound yet must be so conducted that it produces relatively little artifact or damage within the tissue to disturb the morphological integrity. The cytochemical localization of the agent should possess contrast either in density or chemical configuration so that it can be specifically identified even after the tissue is treated with a relatively nonspecific agent such as osmium tetroxide or is stained after sectioning with conventional stains such as uranyl acetate and/or lead citrate.
Localization of gp70 and p30 Murine Type C. Virus Antigens in Thin Section Electron Microscopy Using Novel Immunolatex Spheres and Comparison with Immunoferritin and Immunoperoxidase Methods
Authors: Gonda M.A. , Hager H. , Oroszlan S. , Gilden R.V. , Hsu K.C. 
Published: June 2020

Mammalian type C RNA tumor viruses are composed of several structural proteins that can be identified by molecular weight and location on the virion (1). Rauscher leukemia virus (RLV), a murine type C virus, has a 70,000 dalton glycoprotein (gp70) in its envelope and a 30,000 dalton core protein (p30) as two of its major structural proteins (1,2). Synthetic latex microspheres have been shown to be useful surface markers for the scanning electron microscope (SEM) (3). Presented here is a thin section method utilizing novel latex spheres containing aromatic amines which, when coupled to antibodies by diazotization, act as electron-dense markers for indirect immunoelectron microscopic (IEM) detection of gp70 and p30 antigens of RLV. These results are compared with those obtained by immunoferritin and immunoperoxidase methods.RLV-infected murine JLSV-10 cells were used for all IEM. All reactions prior to fixation were carried out at 4°C. Pelleted cells were resuspended in primary serum, either goat anti-RLV p30, goat anti-RLV gp70, or normal goat, and allowed to react for 30 min. Cells were washed and sedimented 3X in buffer. Cell pellets for indirect immunolatex labeling were resuspended and gently agitated for 30 min in donkey anti-goat IgG coupled to latex spheres.
Ultrastructural Examination of T1 Virus by High Resolution SEM
Authors: Panessa Barbara J. , Broers Alec N. 
Published: June 2020

This non-contractile coliphage has a small capsid, slender hollow tail and lacks an end-plate as well as tail fibers. The work presented here shows the first scanning electron micrographs of intact adsorbed T1 coliphages and demonstrates the presence of repeating morphological subunits comprising the tail which supports the hypothesis of Bradley1. New morphological data about adsorbed phage particles are also revealed.Virus particles were added to log phase E. coli B on agar-goated Si02 slivers, or in nutrient broth, incubated for 10 or 15 minutes at 30°C and fixed in 1.5% glutaraldehyde in 0.1 M cacodylate buffer (pH 7.2). Samples were dried by the critical point method (C02), metal coated (2-5 nm Au-Pd), and examined using the low-loss mode of operation2 in an SEM having a condenser-objective final lens and a lanthanum hexaboride gun3. An accelerating potential of 45KV was used and a beam diameter below 10Å.
Transmission Electron Microscopic Evidence of Rhopheocytosis as the Mechanism of Melanosome Transfer in Human Hair Bulbs
Authors: Harris Ronald T. 
Published: June 2020

Rhopheocytosis is a term first proposed by Marcel Bessis in 1956 to describe the apparent cytophagocytic phenomenon in erythroblast islands of red bone marrow. In this system, rhopheocytosis has been demonstrated to be the mechanism by which ferritin is transferred from reticulum cells (island cells) to erythroblasts. Subsequent to these early studies, the mechanism had not been observed in any other mammalian tissue. The present paper reports TEM evidence that rhopheocytosis is the mechanism by which melanosomes are transferred to living germinal matrix cells in human hair bulbs.Melanin pigmentation in human scalp hair results from the intimate interaction between neural crest-derived melanocytes and epidermis-derived germinal matrix cells. The major functions of melanocytes are to synthesize the pigment melanin from the amino acids tyrosine and phenylalanine, to deposit this substance on a protein-phospholipid structural framework, and to package the complex in granules, the so-called melanosomes.
Structural Homology between Prokaryotic and Eukaryotic Ribosomes
Authors: Boublik M. , Hellmann W. , Jenkins F. 
Published: June 2020

The structural complexity of ribosomes is evident from the large number of their constituents - ribosomal proteins and ribonucleic acids. The simplest known prokaryotic (70S) ribosome from E. coli is composed of 53 different proteins and three ribonucleic acid molecules (23S, 16S and 5S RNA). Eukaryotic (80S) ribosomes also consist of three RNAs (28S, 18S and 5S) but contain a higher number of proteins, approximately 70. The mutual interactions of ribosomal proteins and RNAs determine the final structure and thus the biological activity of the ribosome. As expected for particles with the above composition, ribosomes and both ribosomal subunits have no symmetry or repetition in structure.Electron micrographs of ribosomes (stained with 0.5% aqueous uranyl acetate and deposited on a fine carbon support) show distinct contours and electron dense pattern. Critical evaluation of different views of the two-dimensional projections of the ribosomal contours can provide a reasonable basis for proposing a three-dimensional model of the ribosome.
Ultrastructural Localization of NA+-K+ -Atpase in Rabbit Cornea Using 5-Nitroindoxyl Phosphate as Substrate
Authors: Tsou K. C. , Khatami Mahin 
Published: June 2020

Recently, Leunberger and Novikoff (1) have shown that the endothelial cells are the primary sites of Na+-K+-ATPase, a key mechanism in the control of hydration of cornea. Since this enzyme would be a useful marker for our study of endothelial damage by CO2 laser (2), we have undertaken a comparative study for the localization of this enzyme at ultrastructural level with different methods. In the course of this work we developed a new method with the use of 5-nitroindoxyl phosphate as a synthetic substrate. This new substrate, like p-nitrophenyl phosphate (3), meets the requirements for the demonstration of the K+ activated step of dephosphorylation of ATPase. In addition, it can be used with glutaraldehyde fixed tissue, thereby offering an important advantage over the previous method (3).Rabbit corneas were freshly excised under pentobarbitol anesthesia.
Immuno-Enzyme Histochemistry of Creatine Phosphokinase
Authors: Baba N. , Poe E.T. , Scillian J. , Myser T. 
Published: June 2020

With a commercially available rabbit muscle (MM) type isoenzyme of the creatine phosphokinase (CPK) (Worthington Biochemical), anti-CPK antibody was produced in chicken and goat (Figure 1). Fab' fragments of the chicken and goat IgG were isolated and conjugated with a commercially available horseradish peroxidase (HRP) according to the Nakane method (J. Histochem. Cytochem,, 22:1084, 1974).Rabbit hearts were perfused in vivo with freshly prepared 2% paraformaldehyde solution, and the left ventricular myocardium was fixed for 30 minutes. Forty-micrometer-thick frozen sections of the myocardium were incubated with the Fab'-HRP conjugate overnight at 4°C. After a thorough rinse, the sections were stained for the peroxidase reaction.In an electron microscope, diffuse cytoplasmic staining of the heart muscle cells was noted, indicating the diffuse cytosol distribution of CPK (Figure 2). In addition, there was strong staining of the intermembranous and intracristal space of the mitochondria as well as the M-lines of the myofibrils (Figures 3 and 4).
Adrenocorticotropin Production by a Mammary Carcinoma
Authors: McCarty K.S. , Wallace N.R. , Litaker W. , Wells S. , Eisenbarth G. 
Published: June 2020

The production of adrenocorticotropic hormone by non-pituitary carcinomas has been documented in several tumors, most frequently small cell carcinoma of the lung, islet cell carcinomas of the pancreas, thymomas and carcinoids. Electron microscopy of these tumors reveals typical membrane-limited "neurosecretory" granules. Confirmation of the granules as adrenocorticotropin (ACTH) requires the use of OsO4 as a primary fixative to give the characteristic cored granule appearance in conjunction with immunohistochemical demonstration of the hormone peptide. Because of the rarity of ectopic ACTH production by mammary carcinomas and the absence of appropriate ultrastructural studies in the two examples of such ectopic hormone production in the literature of which we are aware (1,2), we present biochemical and ultrastructural data from a carcinoma of the breast with apparent ACTH production.The patient had her primary tumor in the right breast in 1969. The tumor recurred as visceral and subcutaneous metastases in 1976 and again in 1977.
Destruction of Actin Filaments by Osmium Tetroxide
Authors: Maupin-Szamier P. , Pollard T. D. 
Published: June 2020

We have studied the destruction of rabbit muscle actin filaments by osmium tetroxide (OSO4) to develop methods which will preserve the structure of actin filaments during preparation for transmission electron microscopy.Negatively stained F-actin, which appears as smooth, gently curved filaments in control samples (Fig. 1a), acquire an angular, distorted profile and break into progressively shorter pieces after exposure to OSO4 (Fig. 1b,c). We followed the time course of the reaction with viscometry since it is a simple, quantitative method to assess filament integrity. The difference in rates of decay in viscosity of polymerized actin solutions after the addition of four concentrations of OSO4 is illustrated in Fig. 2. Viscometry indicated that the rate of actin filament destruction is also dependent upon temperature, buffer type, buffer concentration, and pH, and requires the continued presence of OSO4. The conditions most favorable to filament preservation are fixation in a low concentration of OSO4 for a short time at 0°C in 100mM sodium phosphate buffer, pH 6.0.
Cytoplasmic Filaments in the Chick Lens Fiber Cells
Authors: Bradley Ronald H. , Alcala Jose , Maisel Harry 
Published: June 2020

Filaments (average diameter, 12 nm) are a prominent feature of the water- insoluble fraction of chick lens fiber cells (1) (fig. 1). Isolation of the filaments was achieved in the following manner. The lens fiber mass was homogenized in standard salt solution pH 7.2 to which 10 mM B-mercaptoethanol was added. The homogenate was centrifuged at 37,000 g for 20 min. and the pellet washed in buffer until free of soluble proteins (lens crystallins) when tested with antisera to the crystallins. The pellet was then extracted in 8M urea and centrifuged at 77,000 g for 15 min. The membrane-rich pellet was discarded and the urea-soluble fraction was dialysed against the buffer to remove the urea. Negative stain analysis showed that intact filaments were present in the urea-free solution (UFS).A pellet rich in filaments was obtained by centrifugation of the UFS at 77,000 g for 1 hr. (fig. 2).
A Complex Glycoprotein Released from Platelets by Thrombin Action
Authors: Lawler John W. , Slayter Henry S. 
Published: June 2020

Human blood platelets contain a glycoprotein previously called thrombin sensitive protein (TSP) which is released into the extracellular environment as a result of the action of thrombin. TSP had been variously reported to be 150,000 to 190,000 daltons (1) by SDS polyacrylamide gel electrophoresis. A recent report (2) has indicated that TSP is really a 150,000 dalton component produced by reduction of a 450,000 dalton complex macro- glycopeptide, which we have now isolated. We shall call this glycoprotein thrombospondin (TSN) (because it is liberated intact by the action of thrombin from blood platelets), in order to distinguish it from its more commonly identified subunits which may or may not be identical chemically, to each other.TSN is purified by treatment of fresh washed platelets with 3U/ml of thrombin, followed by hirudin treatment to stop thrombin action, and subsequent removal of platelets by centrifugation.
Cell Surface Markers and Labeling Techniques for Scanning Electron Microscopy
Authors: Molday R.S. 
Published: June 2020

Cell surface labeling has provided valuable information on the organization and dynamics of specific antigens and receptors in cell membranes. Such studies have generally utilized fluorescent dyes, radioisotopes, enzymes or biological macromolecules (ferritin, hemocyanin, viruses) bound to specific ligands (antibodies, lectins, hormones and toxins) as visual probes for light and transmission electron microscopy (TEM). More recently, visual markers and labeling methods have been developed for scanning electron microscopy (SEM). These techniques have been used to map the topographical distribution of specific molecules on complex cell surfaces (1).Visualization of cell labeling by SEM relies on the use of macromolecular markers which are resolvable under the SEM. Such markers also must i) be uniform in size and shape to facilitate their identification on cell surfaces, ii) show little, if any, nonspecific binding to cell surfaces, iii) interact with surface specific ligands via covalent bonding or high affinity binding and iv) be stable against degradation or aggregation during labeling and preparation of samples for SEM.
Cell Surface Characteristics of a Human Breast Carcinoma Cell Line (MCF-7)
Authors: Russo J. , Russo I. 
Published: June 2020

Modifications of the acid mucopolysaccharide coat of mammalian cells is considered an important marker of cell transformation in vitro.In the present paper, the ultrastructural localization of acid mucopolysaccharides on the cell surface of MCF-7 cells is reported. MCF-7 is a cell line derived from a metastatic human breast carcinoma which has been cultured in monolayer in Eagle's minimum essential medium for more than five years. Cells growing in monolayer for more than 142 transfers and cells of the same transfer seeded in collagen-coated cellulose sponges (1) were used in these experiments. Both groups of cells were either rinsed three times in caco- dylate buffer, 0.1 M, pH 7.2, and then fixed and stained with ruthenium red RR (2), or labeled and fixed with cationized ferritin (CF) according to Danon's (3).All the cells growing in monolayer had a continuous electron-dense fuzzy layer of RR attached to the outer leaflet of the cell membrane at both the free surface and the intercellular spaces (Fig. 1).
Fine Structural Changes in the Adenohypophyses of Rats Following Destruction of the Pituitary Stalk
Authors: Kovacs K. , Horvath E. , Bilbao J. M. , Laszlo F. A. , Domokos I. 
Published: June 2020

Electrolytic lesions of the pituitary stalk in rats interrupt adenohypophysial blood flow and result in massive infarction of the anterior lobe. In order to obtain a deeper insight into the morphogenesis of tissue injury and to reveal the sequence of events, a fine structural investigation was undertaken on adenohypophyses of rats at various intervals following destruction of the pituitary stalk.The pituitary stalk was destroyed electrolytically, with a Horsley-Clarke apparatus on 27 male rats of the R-Amsterdam strain, weighing 180-200 g. Thirty minutes, 1,2,4,6 and 24 hours after surgery the animals were perfused with a glutaraldehyde-formalin solution. The skulls were then opened and the pituitary glands removed. The anterior lobes were fixed in glutaraldehyde-formalin solution, postfixed in osmium tetroxide and embedded in Durcupan. Ultrathin sections were stained with uranyl acetate and lead citrate and investigated with a Philips 300 electron microscope.
Basal Lamina Formation in DMBA Induced Mammary Carcinoma
Authors: Russo I. , Saby J. , Russo J. 
Published: June 2020

It has been previously demonstrated that DMBA-induced rat mammary carcinoma originates in the terminal end bud (TEB) of the mammary gland by proliferation of intermediate type cells (1). The earliest lesion identified is the intraductal proliferation (IDP), which gives rise to intraductal carcinomas. These evolve to cribriform, papillary and comedo types (2). In the present work, we report the ultrastructural changes that take place in the IDP for the formation of a cribriform pattern.Fifty-five-day-old Sprague Dawley virgin female rats were inoculated intra- gastrically with 20 mg 7,12-dimethylbenz(a)anthracene (DMBA) in 1 ml sesame oil. Non-inoculated, age-matched females were used as controls. Mammary glands from both control and experimental rats were removed weekly from the time of inoculation until 86 days post-inoculation. The glands were fixed and processed for electron microscopy (2).The first change observed in IDP's was the widening of intercellular spaces and the secretion of an electron dense material into these spaces (Fig. 1).
Contamination at Low Temperature
Authors: Wall J. , Bittner J. , Hainfeld J. 
Published: June 2020

Contamination of biological specimens has been a practical limitation for many years. It is especially noticeable in the dark field STEM (Scanning Transmission Electron Microscope) since contamination only occurs near the area irradiated by the beam and since we are most often observing very thin specimens (20 - 40 Å). Contamination can be greatly reduced by baking the specimen to 100°C in vacuum prior to observation, (1), but such heating may alter biological structures and cause heavy atom migration away from heavy atom staining sites.Since contamination results from surface migration (2), it might be eliminated by cooling the specimen to a sufficiently low temperature. The Brookhaven STEM (3).is equipped with a cold stage capable of attaining -170°C with less than 5 Å vibration. Contamination was observed as a function of temperature for a clean carbon film and for two biological specimens. The specimens were prepared on slotted Titanium grids covered by a holey carbon film with thin carbon (˜ 20 A) stretched across the holes.
The Frozen Biological Specimen in Fly Ash Investigations
Authors: Hayes T. L. 
Published: June 2020

Fly ash is the major particulate pollutant resulting from coal combustion. These micron and sub-micron sized particles have been shown to contain many toxic chemical elements (1) and the chemical composition can vary greatly from particle to particle. In studying the biological effects which may be associated with these particles, attention to damage to even a single cell is necessary. Carcinogenesis, in particular, may have an initiating event associated with the transformation of a single cell. Both the exposure in terms of variation in single particle chemistry and biological effect in terms of single cell alterations must be measured at the microscopic level rather than relying exclusively on bulk techniques which average the chemical composition of a great number of particles and the damage to a great many cells.The frozen specimen helps to preserve the chemical properties of the fly ash particles by reducing the number of solvent steps needed during preparation. The biological surface can also be maintained in the frozen specimen with the possibility of either retaining hydration during SEM analysis in .he form of ice or removing the water by freeze drying techniques.
Vesiculation and Loss of the Plasma Membrane along the Midpiece of Physa Sp. Spermatozoon
Authors: Ackerson A. , Koehler L. 
Published: June 2020

The Physidae are among the advanced families of the freshwater snails having very extensive and elaborate genital ducts. To achieve cross fertilization the spermatozoon must travel a long distance along a tortuous path through the oviduct and its secretions. The concept that spermatozoon structure is related to the physiological demands of the fertilization environment has been stated previously (1). The present paper describes a specialized structure associated with the plasma membrane and the loss of the plasma membrane along the midpiece of Physa spermatozoa.In early Physa spermatids, plasma membrane vesiculation is observed concurrently with cellular and nuclear condensation. The midpiece exhibits coiling and folding within the boundaries of the plasma membrane as it develops (Fig. 1). Fig. 2 shows a later stage of maturation in which the plasma membrane becomes closely associated with the midpiece and undergoes extensive vesiculation. The surface of the midpiece is a microtubular sheath.
In situ observation of Dense-Body Release from Hydrated Human Platelets
Authors: Hui S.W. , Costa J.L. , Smith M.A. , Strozewski C.M. 
Published: June 2020

Dense bodies, electron-dense granules are believed to be storage sites for large pools of platelet serotonin, pyrophosphate, adenine nucleotides, and calcium. In order to prove that dense bodies exist as such in living platelets, we examined hydrated human platelets in the electron microscope, utilizing the differentially pumped hydration chamber.Human platelets were resuspended in the sodium chloride-Tris-citrate buffer with 0.35% bovine serum albumin, and were allowed to settle on carbon-coated grids covered with a thin film of liquid. Specimens were viewed and photographed at 100 kV in a Siemens 1A electron microscope equipped with an environmental chamber. The beam dose per micrograph was 5 x 10-5 coulombs/cm2. Although details of some platelets were obscured by a thick film of water, dense bodies were clearly visible in a large proportion of the platelets photographed (Figure 1). The distribution of platelets by dense-body content was similar to that described previously for air-dried whole mounts.