Biology Commons^™

Atomic Force Microscopy Of Nucleoprotein Complexes, Y. L. Lyubchenko, B. L. Jacobs, S. M. Lindsay, A. Stasiak

Scanning Microscopy

Recent data on the AFM studies of nucleoprotein complexes of different types are reviewed in this paper. The first section describes the progress in the sample preparation methods for AFM studies of nucleic acids and nucleoprotein complexes. The second part of this paper reviews AFM data on studies of complexes of DNA with regulatory proteins. These studies include two different types of DNA distortion induced by proteins binding: local bending of DNA at sites of protein binding and formation of large loops due to protein-protein interactions between molecules bound to distant sites along the DNA molecules (DNA looping). The prospects …

Microvascular Corrosion Casting In The Study Of Tumor Vascularity: A Review, M. A. Konerding, A. J. Miodonski, A. Lametschwandtner

Scanning Microscopy

Tumor blood flow is dependent on the structure and three-dimensional (3-D) architecture of the vascular network. The latter can be best studied by scanning electron microscopy of microvascular corrosion casts. However, literature reviews show that nearly all studies using this technique render comparisons of different tumors more difficult since they are mainly based on descriptive terms that might lead to misunderstandings. Qualitative comparisons of 13 experimental and 3 human primary tumors of different origin show a high degree of similarity in the vasculature. Quantitative analysis of these casts reveals similar ranges of parameters such as diameters, intervascular and interbranching distances. …

Thymocyte Proliferation And Apoptosis Induced By Ionizing Radiation, Vera V. Shaposhnikova, Yuri N. Korystov

Scanning Microscopy

Proliferation and apoptosis of rat and mouse thymocytes caused by ionizing radiation were studied. The percentage of proliferating cells was determined by the method of colchicine metaphases and the apoptosis was estimated as DNA fragmentation. In vitro irradiation with 0.05-0.2 Gy was found to stimulate thymocyte proliferation, the maximum was observed at 0.05 Gy for mouse thymocytes and at 0.1 Gy for rat thymocytes. These doses caused a slight decrease in DNA fragmentation, as compared to control. By raising the radiation dose, proliferation was reduced and DNA fragmentation was increased. The results obtained indicate that low radiation doses stimulate cell …

Impact Of Escherichia Coli On Urine Citrate And Urease-Induced Crystallization, A. Edin-Liljegren, H. H. Hedelin, L. Grenabo, S. Pettersson

Scanning Microscopy

Escherichia coli (E. coli) is usually not a urease producer. It is, however, often cultured in urinary phosphate containing calculi including ammonium magnesium phosphate stones. This suggests the possibility that E. coli might be involved in stone forming process. The effect of E. coli on urine citrate and urease-induced crystallization in human urine has been studied in vitro. E. coli was found to strongly reduce urine citrate (after 48 hours). In the E. coli inoculated samples, the urease-induced crystallization was increased. There was a strong correlation, r = 0.8, between the citrate decrease and the increase in calcium precipitation. The …

A Reflection Upon The Applicability Of Electron Beam Induced Current (Ebic) As A Sensitive Microanalytical Technique (Ppb Range) For Silicon Materials Research, Martin Kittler, Winfried Seifert

Scanning Microscopy

This paper discusses the application of electron-beam-induced current (EBIC) technique as a tool which is able to provide at least qualitative microanalytical information not available from other techniques. Three examples are given which demonstrate a sensitivity in the parts per billion (ppb) range: temperature dependence of dislocation contrast as a fingerprint of level of metal (Cu) contamination, iron determination down to 1013 atoms per cm3, and visualization of phosphorous striations in silicon grown by float-zone (FZ) method (FZ-grown Si).

Microanalytical information by EBIC is rather indirect and, usually, identification of the impurity species is not possible. Conclusions about impurity content …

Apoptosis And Calcification, Kookmin M. Kim

Scanning Microscopy

Calcification in necrosis has long been known. Of the tissue components, the cells are most vulnerable. Nevertheless, little attention has been paid to the role of cell death in calcification. This review attempts to update the mechanism of calcification with an emphasis on the role of apoptosis in calcification. A brief review on the basic sciences relevant to calcification is followed by a discussion of abnormal Ca²⁺ and P_i homeostasis in cell injury and apoptosis. Concomitant increases in Ca²⁺ and P_i in blebs (and matrix vesicles) formed by apoptotic and/or necrotic cells are apparently the primary …

Interactions Of Low-Energy Electrons With Atomic And Molecular Solids, Leon Sanche

Scanning Microscopy

Low energy electrons are involved in a large number of analytical techniques for material analysis either as secondary particles or as the primary excitation source. The interaction of these electrons near the surface of solids can be investigated with high-resolution low-energy electron-beam techniques. The results of experiments performed on atomic and molecular solids in the range 0-30 eV with such techniques are reviewed in the present article. The major types of experiments are briefly described and examples of the results obtained from them are given to illustrate the basic mechanisms which control the electron-solid interactions and to provide a description …

Thermal Stability Of Polystyrene Latex Self-Assembled Arrays Studied By Atomic Force Microscopy, Igor Nevernov, Claudio Nicolini

Scanning Microscopy

Preliminary observation of the heat softening of self-assembled polystyrene latex arrays on the submicron scale using atomic force microscopy is reported. Samples of latex self-assembled arrays have been studied in the temperature range from the room temperature up to 120°C. It has been shown that the submicron scale structure remains stable up to the softening point of polystyrene. The experimental set-up used is described and the results obtained are discussed.

Low Temperature Scanning Electron Microscopy Of Clay And Organic Constituents And Their Relevance To Soil Microstructures, C. Chenu, D. Tessier

Scanning Microscopy

Low temperature scanning electron microscopy (LTSEM) is essential for studying the microstructure of small-sized soil constituents such as clays and organic matter. These hydrated and swelling materials naturally undergo drastic changes in water potential and water content in soils. The cryofixation of clays and organic macromolecules by immersion in cryogens and their LTSEM observation are evaluated. The microstructures of clay minerals, polysaccharide macromolecules and their associations, as revealed by LTSEM, contribute to a better understanding of the water retention properties and physical stabilities of these major soil constituents.

Induction Of Crystallization Of Calcium Oxalate Dihydrate In Micellar Solutions Of Anionic Surfactants, H. Füredi-Milhofer, L. Tunik, N. Filipovic-Vincekovic, D. Skrtic, V. Babic-Ivancic, N. Garti

Scanning Microscopy

Calcium oxalate dihydrate (CaC₂O₄.(2+x)H₂O; COD; x ≤ 0.5) does not readily crystallize from electrolytic solutions but appears as a component in crystalluria. In this paper, we review in vitro studies on the factors responsible for its nucleation and growth with special attention given to the role of surfactants. The following surfactants were tested: dodecyl ammonium chloride (cationic), octaethylene monohexadecylether (non-ionic), sodium dodecyl sulfate (SOS, anionic), dioctyl sulphosuccinate (AOT, anionic), and sodium cholate (NaC, anionic). The cationic and some of the anionic surfactants (SOS, AOT) induced different habit modifications of growing calcium oxalate crystals by …

Work Function Dependence Of Charge Transfer In Desorption And Sputtering Of Atoms From Surfaces, Sarah J. Steuber, Peter Nordlander, Hongxiao Shao, David C. Langreth

Scanning Microscopy

Using a recently developed many-electron theory, we investigate the work function dependence of charge transfer during desorption and sputtering of atoms from metal surfaces. We investigate the effects of substrate bandwidth, atomic velocity and level degeneracy on the charge transfer. We show that many-electron interactions introduce relatively small but measurable effects on the work function dependence of the charge transfer. We find that these effects can be stronger for negative ion states than for positive ion states. The reason is that for negative ions, a strongly correlated Kondo state may be formed near the surface.

Endoarticular Loose Bodies And Calcifications Of The Disk Of The Temporomandibular Joint: Morphological Features And Chemical Composition, C. Piacentini, C. Marchetti, A. Callegari, M. Setti, G. Bernasconi, U. Baciliero, P. Menghini, C. Brusotti

Scanning Microscopy

We studied articular disks and endoarticular loose bodies taken from patients suffering from different types of temporomandibular joint (TMJ) pathology. The scanning electron microscopy (SEM) analysis of the disks and the endoarticular loose bodies was followed by a chemical-compositional analysis using an energy dispersive spectrometer (EDS) and by characterization of the crystalline phases by X-ray powder diffraction (XRD). The articular disks were composed of a central radio-opaque area lacking any evident structural features, surrounded by compact bundles of collagen fibers. EDS and XRD analyses showed that endodiscal radio-opaque areas were hydroxyapatite. By SEM, we observed a fibrous network only in …

Low Temperature Techniques As A Tool In Plant Pathology, Sigrun Hippe-Sanwald

Scanning Microscopy

In plant pathology, low temperature preparation techniques now appear to be feasible methods to stabilize the dynamic ultrastructure of the host-(plant)-pathogen (fungi) interaction for an analysis by transmission electron microscopy. A well defined ultrastructure of small organisms (fungi) and large biological samples such as plant material and as well as the plant-pathogen (fungus) infection sites are presented. The mesophyll tissue of Arabidopsis thaliana is characterized by homogeneously structured cytoplasm closely attached to the cell wall. Infection sites of stem rust (Puccinia graminis f. sp. tritici) on primary leaves of wheat (Triticum aestivum) and powdery mildew (Erysiphe …

Atomic Force Microscopy Of Neuron Networks, A. Cricenti, G. De Stasio, R. Generosi, P. Perfetti, M. T. Ciotti, D. Mercanti

Scanning Microscopy

We imaged uncoated neuron networks by an atomic force microscope in the repulsive regime of contact mode. Images of granule cells and their axons have been clearly revealed with details smaller than 20 nm. The good stability of the sample and the mechanical reproducibility of the microscope allowed the imaging of a neuron culture area of several square microns. By combining tens of images, we were able to reconstruct a highly defined neuronal network. Furthermore, the images were very reproducible over repeated scanning acquisition, demonstrating the mechanical and thermal stability of the instrument-sample system.

Human Skin Physiology Studied By Particle Probe Microanalysis, B. Forslind, M. Lindberg, K. G. Malmqvist, J. Pallon, G. M. Roomans, Y. Werner-Linde

Scanning Microscopy

Particle probe methods (electron probe and proton probe X-ray microanalysis) have been applied to investigate the distribution of elements and water over the different layers of the epidermis. For major elements, electron probe X-ray microanalysis (XRMA) provides the advantage of superior spatial resolution, but for trace element analysis the more sensitive proton probe (particle induced X-ray emission, PIXE) analysis has to be used. On a dry weight basis, the concentration of S is rather constant across the epidermis, whereas the concentrations of P, K, Cl and Na show gradients with high levels in stratum germinativum (basale) and stratum spinosum but …

Comparison Of Dna Fragmentation And Color Thresholding For Objective Quantitation Of Apoptotic Cells, D. R. Plymale, D. S. Ng Tang, C. D. Fermin, D. E. Lewis, D. S. Martin, R. F. Garry

Scanning Microscopy

Apoptosis is a process of cell death characterized by distinctive morphological changes and fragmentation of cellular DNA. Using video imaging and color thresholding techniques, we objectively quantitated the number of cultured CD4 + T-lymphoblastoid cells (HUT78 cells, RH9 subclone) displaying morphological signs of apoptosis before and after exposure to γ-irradiation. The numbers of apoptotic cells measured by objective video imaging techniques were compared to numbers of apoptotic cells measured in the same samples by sensitive apoptotic assays that quantitate DNA fragmentation. DNA fragmentation assays gave consistently higher values compared with the video imaging assays that measured morphological changes associated with …

Imaging Of Cherenkov And Transition Radiation From Thin Films And Particles, N. Yamamoto, A. Toda

Scanning Microscopy

Cherenkov radiation and transition radiation, which are generated by high energy electrons with constant velocity, can be detected in a transmission electron microscope using a cathodoluminescence (CL) detection system. The characteristic peaks due to interference were observed in the emission spectra from thin films of mica, silicon and silver, and their dependence on sample thickness and accelerating voltage was studied. Particles of BaTiO3 and MgO also showed characteristic feature in the spectra which changed with their size. A recently developed imaging system revealed the two-dimensional intensity distribution of these radiations; for example, oscillating contrast, such as equal thickness contour appears …

Crystalline Composition Of Equine Urinary Sabulous Deposits, M. Díaz-Espiñeira, E. Escolar, J. Bellanato, J. A. Medina

Scanning Microscopy

The composition and crystal morphology of 141 equine sabulous deposits were determined by infrared spectroscopy (IR), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The IR analysis revealed that all investigated deposits contained calcium carbonates (calcite, CaCO₃, and/or vaterite, CaCO₃) as major constituents; 42 samples were composed of calcite and vaterite, 33 of calcite, 18 of calcite/vaterite and calcium oxalate, and 17 of vaterite. The remaining specimens contained calcite/vaterite and other compounds (calcium phosphates, sulphate and/or oxalates and/or silica). The examination of 44 selected samples by means of SEM/EDX, revealed the characteristic morphology and …

Photon Emission Induced By The Scanning Tunneling Microscope, Richard Berndt

Scanning Microscopy

By using the tip of a scanning tunneling microscope (STM) as a local source for electrons (or holes) light emission can be excited from metals, semiconductors and molecules. Using this technique, it is possible to combine the high spatial resolution of STM with optical techniques. We review results obtained using a variety of modes of measurements including fluorescence spectroscopy, isochromat spectroscopy and simultaneous mapping of photon emission and surface topography. In spatial maps of the photon emission, clear contrasts are observed with lateral resolutions below 1 nm which are related to the geometric and electronic structure of the sample and …

Discovery Of The Federally Endangered Freshwater Mussel, Epioblasma Obliquata Obliquata (Rafinesque, 1820) (Unionidae), In Ohio, Michael A. Hoggarth, Daniel L. Rice, Diana M. Lee

Biology and Earth Science Faculty Scholarship

Discovery of the purple catspaw, Epioblasma obliquata obliquata, in Killbuck Creek, Coshocton County, OH, is reported. This subspecies of unionid mollusc was thought to have been extirpated from the state in the mid to late 1800s and was known only from two nonreproductive populations in Kentucky and Tennessee. The mussel was thought to be on the verge of extinction. Fifteen living and 23 dead specimens of this subspecies were collected in September 1994 from Killbuck Creek. This is the largest known population of this rare subspecies and it is the only known population to currently support breeding individuals. It is …

Pattern Of Disease After Murine Hepatitis Virus Strain 3 Infection Correlates With Macrophage Activation And Not Viral Replication, M. Pope, O. Rotstein, E. Cole, S. Sinclair, Rebecca D. Parr, B. Cruz, R. Fingerote, S. Chung, R. Gorczynski, L. Fung, J. Leibowitz, Y. S. Rao, G. Levy

Faculty Publications

Murine hepatitis virus strain (MHV-3) produces a strain-dependent pattern of disease which has been used as a model for fulminant viral hepatitis. This study was undertaken to examine whether there was a correlation between macrophage activation and susceptibility or resistance to MHV-3 infection. Peritoneal macrophages were isolated from resistant A/J and susceptible BALB/cJ mice and, following stimulation with MHV-3 or lipopolysaccharide (LPS), analyzed for transcription of mRNA and production of interleukin-1 (IL-1), tumor necrosis factor alpha (TNF-alpha), transforming growth factor beta (TGF-beta), mouse fibrinogen-like protein (musfiblp), tissue factor (TF), leukotriene B4, and prostaglandin E2 (PGE2). Macrophages from BALB/cJ mice produced …

On The Dangers Of Interpopulational Transfers Of Monarch Butterflies, Lincoln P. Brower, Linda S. Fink, Andrew Van Zandt Brower, Kingston L. H. Leong, Karen Oberhauser, Sonia Altizer, Orley Taylor, Daniel Vickerman, William H. Calvert, Tonya Van Hook, Alfonso Alonso-Mejia, Stephen B. Malcolm, Denis F. Owen, Myron P. Zalucki

Biological Sciences

No abstract provided.

The Impact Of The New Management Package On Smaller Operators In The Western Rock Lobster Fishery, Ross Gould

Fisheries Management Papers

For the 1993/94 western rock lobster fishing season several new management strategies were introduced. The objective of the changes to the management package was to protect the rock lobster fishery. It was also to provide sufficient breeding stock to ensure viability of the industry. The most significant new measure was a temporary (two seasons) 18 percent pot reduction. Other changes were also made. There were considered sound reasons for reviewing and changing the previous management package. Despite this, some fishermen were critical of the new management package, and claimed that it unfairly disadvantaged smaller operators. Against this background, the Department …

2,4-Dichlorophenoxyacetic Acid-Degrading Bacteria Contain Mosaics Of Catabolic Genes, R. R. Fulthorpe, C. Mcgowan, O. V. Maltseva, William E. Holben, J. M. Tiedje

Biological Sciences Faculty Publications

DNA from 32 2,4-dichlorophenoxyacetic acid (2,4-D)-degrading bacteria from diverse locations was probed with the first three genes of the well-known 2,4-D degradation pathway found in Alcaligenes eutrophus JMP134(pJP4). The majority of strains did not show high levels of homology to the first three genes of the 2,4-D degradation pathway, tfdA, -B, and -C. Most strains showed combinations of tfdA-, B-, and C-like elements that exhibited various degrees of homology to the gene probes. Strains having the same genomic fingerprints (as determined by repetitive extragenic palindromic PCR) exhibited the same hybridization pattern regardless of the geographic origin of the …

Isolation And Analysis Of Nephritic-Producing Immune Complexes In Plasmodium Berghei-Infected Mice, Clarence Lee, Eric Toran

Department of Biology Faculty Publications

A nephritic condition was developed by infecting Swiss Webster albino mice with the malarial parasite Plasmodium berghei NK 65. These animals were tested for urinary protein and the presence of circulating immune complexes using reagent strips and a polyethylene glycol (PEG) precipitation assay. The circulating immune complexes were isolated from the sera using both affinity chromatography and PEG precipitation and from the kidney by acid elution. The isolated complexes were dissociated into their individual components and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The components of the complexes were transferred to nitrocellulose sheets and probed for the presence of …

The Cytoplasmic Tail Domain Of The Vacuolar Protein Sorting Receptor Vps10p And A Subset Of Vps Gene Products Regulate Receptor Stability, Function, And Localization, Joan Lin-Cereghino, Eric G. Marcusson, Scott D. Emr

College of the Pacific Faculty Articles

VPS10 of Saccharomyces cerevisiae encodes a type I transmembrane receptor protein required for the sorting of the soluble vacuolar hydrolase carboxypeptidase Y (CPY). To characterize the essential structural features and intercompartmental transport itinerary of the CPY receptor, we have constructed mutant forms of Vps10p that alter the carboxyterminal cytoplasmic tail of the protein. In addition, we have analyzed the effect these mutations as well as mutations in several VPS genes have on the function, stability, and localization of Vps10p. Although wild-type Vps10p is very stable over a 3-h chase period, overproduction of Vps10p results in PEP4-dependent degradation of the receptor. …

Cells Are Not Just Bags Of Water: A Personal Appreciation Of The Work Of Dr. Brij L. Gupta And His Contribution To Biological X-Ray Microanalysis, Alice Warley

Scanning Microscopy

This paper surveys the contribution made by the work of Dr. B.L. Gupta to the science of biological X-ray microanalysis. A brief biographical sketch of Brij's early years is given, this is followed by considerations about the models for water transport across epithelia. The ultrastructural and histochemical studies carried out by Brij Gupta and colleagues are reviewed to introduce the historical need for the use of EPXMA for the study of ion and water transport in epithelia. The outstanding contribution made by Brij Gupta's work in this field is outlined, and his understanding of the subcellular distribution ions in other …

The Effect Of Ionizing Irradiation On Type I Collagen Of The Tail In Growing Mice: A Histology And Electron Microscopy Study, M. Q. Yang, E. Kjellén, C. H. Håkansson, M. Palmegren

Scanning Microscopy

In order to examine the effect of radiation on growing tissue, especially the fibroblasts and their end-product, the collagen fibres, tails from 24 mice were irradiated at an age of 8 days with 20 Gy and 30 Gy (>°Co). Tails from 18 animals served as controls. Six mice from each group were sacrificed on day 8, 20 and 30. Transmission electron microscopy was used to examine the fibroblasts and the collagen fibrils. Non-irradiated fibroblasts had a nucleus rich in chromatin and an abundant endoplasmic reticulum with cistemae and condensing vacuoles.

On day 20, approximately 50 % , and on …

Elicitor-Induced Resistance In Tomato Plants Against Fungal Pathogens: Ultrastructure And Cytochemistry Of The Induced Response, Nicole Benhamou

Scanning Microscopy

The introduction of gold cytochemistry in plant pathology has opened new avenues for accurately localizing molecules thought to play important biological functions in the plant metabolism. In an effort to understand the process associated with the induction of plant disease resistance, we investigated the effect of fungal elicitors on the cellular response of tomato root tissues during attack by Fusarium oxysporum f. sp. radicis-lycopersici, the causal agent of tomato crown and root rot. Chitosan was found to induce marked morphological and ultrastructural changes in the fungus grown in pure culture, including cytoplasm aggregation and abnormal deposition of an amorphous …

Morphological Effects Of Glycosaminoglycans On Calcium Oxalate Monohydrate Crystals, Y. Shirane, Y. Kurokawa, Y. Sumiyoshi, S. Kagawa

Scanning Microscopy

The effects of individual glycosaminoglycan (GAG) species on calcium oxalate monohydrate (COM) crystal growth were studied in vitro by the observation of crystal morphology grown in a supersaturated calcium oxalate solution in the presence of GAGs using optical and scanning electron microscopes. GAGs affected the morphology of COM crystals differently depending on the species. The growth rates of the crystals formed in the presence of chondroitin-6-sulfate (ChS-C) were higher in length and lower in width and thickness than those of control crystals. The incorporation of dermatan sulfate or heparin into the crystals formed in the presence of these GAGs was …