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Improved Visualization Of Dna In Aqueous Buffer With The Atomic Force Microscope, Magdalena Bezanilla, Carlos J. Bustamante, Helen G. Hansma

Scanning Microscopy

An improved method has been developed for imaging deoxyribonucleic acid (DNA) in aqueous buffer with the atomic force microscope (AFM). DNA on untreated mica can be imaged in aqueous buffer with the AFM if the DNA is deposited onto the mica in a buffer with HEPES and MgCl₂, if the sample is rinsed thoroughly with high water pressure, and if the imaging is done with an electron beam-deposited (EBD) tip that has been deposited in the scanning electron microscope (SEM). The water rinse removes DNA that is otherwise easily scraped off the substrate. There is evidence that sharper …

Quantitative Elemental Mapping Of Biomedical Specimens Using The Nuclear Microprobe., Jan Pallon, John Knox

Scanning Microscopy

Quantitative and structural elemental information is available from the nuclear microprobe through a time consuming fit of the (X-ray) spectrum at each point. An alternative technique is proposed which greatly shortens the analysis procedure and allows an increased number of samples to be processed. The method discussed here is to create elemental maps which, when they are divided by the charge/pixel and multiplied by a scaling factor, will form quantitative maps. The scaling factors are obtained from a calibration procedure comparing a large number of fitted X-ray spectra with the corresponding contents of selected energy windows. The technique also allows …

Ischemia/Reperfusion Injury Of The Ascending Colon In Ponies: A Correlative Study Utilizing Microvascular Histopathology And Corrosion Casting, B. J. Darien, P. A. Sims, W. C. Stone, D. R. Schilly, R. R. Dubielzig, R. M. Albrecht

Scanning Microscopy

Volvulus of the ascending colon (ACV) in the horse results in microvascular injury and necrosis of the intestinal mucosa. This study investigated the site and type of microvascular injury which occurs within the mucosa and sub mucosa following ACV. Histopathology of volvulus treated ponies demonstrated mucosa! necrosis with microvascular hemorrhage and thrombosis. Thrombi occurred within the subepithelial capillaries and edema and hemorrhage developed throughout the mucosa and submucosa. Vascular casts allowed 3-D viewing of samples obtained from the entire pelvic flexure and demonstrated two distinct microvascular changes: 1) disruption of the colonic glandular capillary network occurred concomitantly with the …

X-Ray Microanalysis Of Camp-Induced Ion Transport In Ncl-Sg3 Sweat Gland Cells, Ann-Christin Mörk, Godfried M. Roomans

Scanning Microscopy

cyclic AMP (cAMP)-induced ion transport in a human sweat gland cell line, NCL-SG3, was investigated by X-ray microanalysis. Stimulation with cAMP caused a decrease in cellular Cl and K content in cells grown on impermeable as well as permeable supports. In cells grown on plastic coverslips or Transwell inserts stimulation with cAMP caused a significant decrease of the Na concentration, but no significant effect on the intracellular Na was seen on cells grown on grids. cAMP had no significant effect on the intracellular Ca concentration.

Caesium On Si(100) Studied By Biassed Secondary Electron Microscopy, M. Azim, C. J. Harland, T. J. Martin, R. H. Milne, J. A. Venables

Scanning Microscopy

An ultra-high vacuum scanning electron microscope (UHV-SEM) has been used to study sub-monolayers of Cs on Si(100) surface. Cs adsorption on the surface causes a considerable change in the work function. Coverages below 1/2 monolayer (ML) have been estimated by correlating the work function changes with the secondary electron (SE) signal. It has been found that this signal is sensitive down to ~ 0.005 ML when the sample is biassed to a few hundred volts.

Electron trajectories from a biassed sample have been simulated for electrons originating from different areas with different work functions across the sample. This indicates that …

Calcium Phosphate In Aspergillosis Of The Maxillary Sinus, Hidekuni Tanaka, Toshiro Sakae, Hiroyuki Mishima, Hirotsugu Yamamoto

Scanning Microscopy

The unique appearance of apatite in fungus balls of aspergillosis in the maxillary sinus was investigated using scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray microdiffraction and Fourier transform infrared spectroscopy (FT-IR). Rod-shaped fragments with tubular structures, and globular vesicles covered with conidia were observed in the fungus balls. Massive fragments of a solid substance were demonstrated inside the fungus balls. Calcium and phosphate were detected in necrotic areas of the fungus balls by EDS. X-ray microdiffraction and FT-IR showed the presence of an apatite-like substance, but failed to demonstrate the presence of calcium oxalate crystals usually found in such …

Effects Of Modulated And Continuous Microwave Irradiation On Pyroantimonate Precipitable Calcium Content In Junctional Complex Of Mouse Small Intestine, Z. Somosy, G. Thuróczy, J. Kovács

Scanning Microscopy

The pyroantimonate precipitable calcium content of intestinal epithelial cells was investigated in mice following total body irradiation with 2450 MHz continuous and low frequency (16 Hz) square modulated waves. In the control animals the reaction products appeared in the intercellular space of adjacent cells including intermediate junctions and desmosomes and were absent in the area of tight junctions. Immediately after low frequency modulated microwave irradiation at 0.5 and 1mW/cm² power densities, a rapid distribution of pyroantimonate precipitable calcium content was observed. The pyroantimonate deposits were located on the cytoplasmic side of lateral membrane, in the area of junctional complex, …

Optimization And Application Of Jet-Freezing, T. Müller, S. Moser, M. Vogt, C. Daugherty, M. V. Parthasarathy

Scanning Microscopy

Cryofixation is considered to be the best method for immobilizing biological material in its natural state. In jet-freezing, the specimen typically is sandwiched between two carriers and kept in place while a coolant is moved very rapidly against the opposite surfaces. The JFD 030 jet-freezing device has been used to optimize the operating parameters. The course of the temperature in place of a specimen was measured with thermocouples and recorded by an IBM-compatible personal computer using a specifically developed software program. Mean cooling rates, over the temperature range of 273K to 173K, achievable with different cryogens, including the non-flammable HCFC …

Scanning Electron Microscopy Of High-Pressure-Frozen Sea Urchin Embryos, Paul Walther, Ya Chen, Marek Malecki, Sara L. Steffen Zoran, Gerald P. Schatten, James B. Pawley

Scanning Microscopy

High-pressure-freezing permits direct cryo-fixation of sea urchin embryos having a defined developmental state without the formation of large ice crystals. We have investigated preparation protocols for observing high-pressure-frozen and freeze-fractured samples in the scanning electron microscope. High-pressure-freezing was superior to other freezing protocols, because the whole bulk sample was reasonably well frozen and the overall three-dimensional shape of the embryos was well preserved. The samples were either dehydrated by freeze-substitution and critical-point-drying, or imaged in the partially hydrated state, using a cold stage in the SEM. During freeze-substitution the samples were stabilized by fixatives. The disadvantage of this method was …

Micro-Pixe (Particle Induced X-Ray Emission) Analysis Of Aluminum In Rat-Liver Using Mev Heavy Ion Microprobes, Yuji Horino, Yoshiaki Mokuno, Atsushi Kinomura, Kanenaga Fujii, Sakae Yumoto

Scanning Microscopy

Heavy ion microprobes (HIM) such as 3 MeV Si²⁺ and 3 MeV p²⁺ have been applied to the elemental analysis by PIXE (proton-induced X-ray emission). It was found that silicon and phosphorus microprobes have several times higher sensitivity for aluminum Kα X-rays than 2 MeV proton microprobes, and detection limits were more favorable in a phosphorus microprobe. Using a 3 MeV p²⁺ microprobe, the liver of a rat, which had been injected with aluminum-lactate, was investigated and it was found that aluminum segregates in areas with a dimension of about 10 μm. These areas could hardly be …

Intracellular And Extracellular Elemental Composition Of The Endolymphatic Sac Studied By X-Ray Microanalysis, Romuald Wroblewski

Scanning Microscopy

X-ray microanalysis was performed along with light microscopy (LM) on rapidly frozen and cryo-sectioned endolymphatic sac tissues of adult guinea pigs, to determine the elemental composition of the different cell types in this tissue as well as the content of the sac lumen. The morphological preservation and spatial resolution of cryo-sectioned endolymphatic sac was found adequate for the identification of the different cell types of the sac in the transmission electron microscope. Further cell type identification was performed by comparing scanning transmission electron microscopy images with LM images on adjacent serial sections. X-ray microanalysis demonstrated differences between epithelial and sub-epithelial …

Clock Control Of Circadian Changes Of Ommatidial Structure In The Cockroach, Leucophaea Maderae (L.), Zhuming Zhang

Masters Theses & Specialist Projects

All eukaryotic organisms display rhythms which persist under constant environmental conditions with periods of approximately, but very seldom exactly, 24 hours. Such rhythms are "circadian" and are driven by an internal "biological clock." Circadian rhythms of locomotor activity, retinal sensitivity to light and ommatidial morphology have been characterized in the cockroach, Leucophaea maderae (L.). It is not known whether the same clock(s) controls both circadian rhythms of electroretinogram (ERG) amplitude and morphological changes of the compound eye. In order to determine whether the location of the clock that controls morphological changes is in the same location as the one that …

Characterization Of Bartonella-Bacilliformis Flagella And Effect Of Antiflagellin Antibodies On Invasion Of Human Erythrocytes, David C. Scherer, Isaure Deburon-Connors, Michael F. Minnick

Biological Sciences Faculty Publications

Bartonella bacilliformis is the etiologic agent of Oroya fever in humans. Flagellum-mediated motility has been postulated as a major virulence factor for invasion of host cells. To address this hypothesis, we purified and characterized flagella from strain KC584 and then assessed their role in human erythrocyte association and invasion. Electron microscopy of the flagellar preparation showed a high concentration of filaments with a mean wavelength of 800 nm. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis, immunoblot analysis, and KBr density gradient centrifugation indicated that the flagellar filament is composed of a polypeptide of 42 kDa. The flagellin is partially (ca. 50%) resistant …

In Vivo & In Vitro Effects Of Light On Ommatidial Morphology In The Cockroach, Leucophaea Maderae, Channon Yule

Masters Theses & Specialist Projects

Clock-driven endogenous circadian rhythms in ommatidial morphology have been reported in Leucophaea maderae. The parameters used to measure changes in ommatidial morphology over time were palisade layer and rhabdom areas and the organization of lightscreening pigment granules about the rhabdom. The fact that the palisade layer area only partially returned to the light-adapted state in vivo during subjective midday was indicative of a passive mechanism, not involving the clock output. Complete return of the palisade layer area to the light-adapted state during the daytime in animals held under LD 12:12 indicated light might play an active role. Temporal changes …

The Mayfly Newsletter, Peter M. Grant

The Mayfly Newsletter

The Mayfly Newsletter is the official newsletter of the Permanent Committee of the International Conferences on Ephemeroptera.

Electrophysiological Properties Of Identified Classes Of Lamprey Spinal Neurons, James T. Buchanan

Biological Sciences Faculty Research and Publications

1. As part of a continuing analysis of the mechanisms of the central pattern generator underlying fictive swimming in lamprey, a systematic survey of electrophysiological properties of lamprey neurons was made in the in vitro spinal cord preparation with the use of intracellular current-clamp recordings. A total of 70 neurons was included in the study, representing 6 classes of spinal neurons. The classes were myotomal motoneurons, three classes of interneurons involved in fictive swimming [lateral interneurons, nerve cells with contralateral and caudal projecting axons (CC interneurons), and excitatory interneurons], and two classes of interneurons involved in sensory processes (edge cells …

Xenopus Laevis As A Model Organism, David C. Cannatella, Rafael O. De Sá

Biology Faculty Publications

Model organisms are often assumed to be representative of some more inclusive taxon of which the species is a part. This assumption leads to mistaken generalizations about the evolutionary and comparative significance of the data gathered. This paper reviews com? parative and evolutionary studies of Xenopus laevis and its relatives. Phylogenetic analysis of data from DNA sequences and morphology indicate that Xenopus is monophyletic and that Silurana is its sister group. The most basal lineages of Pipidae diverged prior to the breakup of Gondwana. The bizarre morphology of Xenopus is in part due to changes in the mode of meta? …

Complete Nucleotide Sequence Of Psti-L Fragment Of Tanapox Virus Genomic Dna, Sarah J. Neering

Masters Theses

Tanapox virus (TPV), of the genus Yatapoxvirus, is a human poxvirus that was originally isolated from the Tana River Valley in Kenya in 1962. TPV produces a mild disease characterized by a short febrile illness associated with one or more nodular skin lesions. Although there have been limited studies on TPV, other poxviruses such as vaccinia virus, have been extensively characterized and their genomic DNAs sequenced. In order to examine the molecular features of TPV, we have cloned approximately 17% of the genomic DNA. TPV DNA was digested with Pstl restriction endonuclease and cloned into pUC19. The Pst …

Migration Of Epithelium During Phenytoin-Dependent Gingival Overgrowth In Mice, S. H. Ashrafi, B. Atassi, R. Erickson, T. Sabet

Scanning Microscopy

A small cavity was made in the mesiopalatal area of the maxillary first molar adjacent to the gingiva. Mice were maintained on 40 mg/kg phenytoin (or on diluent for control) by daily intraperitoneal injections. After 9 weeks, light microscopic observations revealed that in experimental mice, epithelial cells migrated towards the cavity and covered it. In controls, epithelial cell migration towards the cavity did not occur. For scanning electron microscopic (SEM) studies, specimens were fixed in 4% glutaraldehyde in 0.1 M phosphate buffer, pH 7.2, for 2 hours, dehydrated, critical point dried and coated with gold. The surface of the outer …

Technical Improvements In Corrosion Casting Of Small Specimens: A Study On Mesonephric Tubules And Vessels Of Chicken Embryos, A. Carretero, H. Ditrich, M. Navarro, H. Splechtna, J. Ruberte

Scanning Microscopy

The injection technique for corrosion casting of small, embryonic material can be improved by using a "chemical ligature" (cyanocrylate). With this simple method, leakage of the resin at the injection site is prevented and the mechanical stability of the cannula-vessel coupling is improved.

The blood vascular system of chicken embryos as small as Hamburger-Hamilton stage 24 (approximately 4.5 days of incubation) has successfully been injected using this procedure. Corrosion casts of the mesonephric tubular system have been made in a similar manner. Additionally, a simple way for secure transport of the fragile casts by immersion in 10% gelatin is suggested.

Affinity Panning Of A Library Of Peptides Displayed On Bacteriophages Reveals The Binding Specificity Of Bip, Sylvie Blond-Elguindi, Steven E. Cwirla, William J. Dower, Robert J. Lipshutz, Stephen R. Sprang, Joseph F. Sambrook, Mary Jane H. Gething

Biological Sciences Faculty Publications

We have used affinity panning of libraries of bacteriophages that display random octapeptide or dodecapeptide sequences at the N-terminus of the adsorption protein (plll) to characterize peptides that bind to the endoplasmic reticulum chaperone BiP and to develop a scoring system that predicts potential BiP-binding sequences in naturally occurring polypeptides. BiP preferentially binds peptides containing a subset of aromatic and hydrophobic amino acids in alternating positions, suggesting that peptides bind in an extended conformation, with the side chains of alternating residues pointing into a cleft on the BiP molecule. Synthetic peptides with sequences corresponding to those displayed by BiP-binding bacteriophages …

Cross-Sections For Electron Scattering Accompanied By Ionization Of Inner-Shells, M. Kotera, K. Yamamoto, H. Suga

Scanning Microscopy

A method is presented to describe the electron scattering process at an ionization of inner-shell electrons. The differential cross-section with the energy transfer and the momentum transfer is calculated using the expression of the generalized oscillator strength. This cross-section and the total ionization cross-section are fairly close to the results obtained by the Gryzinski equation. The photo-absorption cross-section obtained by the present treatment shows good agreement with the experimental data in a wide range of the photon energy. Based on the present treatment, the scattering angle distribution of the primary electron is calculated.

Body Size In Amblyrhiza Inundata (Rodentia, Caviomorpha), An Extinct Megafaunal Rodent From The Anguilla Bank, West Indies: Estimates And Implications, Audrone R. Biknevicius, Donald A. Mcfarlane, Ross D. E. Macphee

WM Keck Science Faculty Papers

Rodent species typically evolve larger mean body sizes when isolated on islands, but the extinct caviomorph Amblyrhiza inundata, known only from Quaternary cave deposits on the islands of Anguilla and St. Martin (northern Lesser Antilles), provides an unusually dramatic example of insular gigantism. Here we report on a series of body mass estimates for Amblyrhiza using predictive equations based on anteroposterior diameters and cortical cross-sectional areas of humeral and femoral diaphyses. Analyses of 14 isolated specimens (5 femoral, 9 humeral), all representing adult or near adult animals, yield body mass estimates ranging from slightly less than 50 kg to more …

Proceedings Of The Charter Boat Management Workshop Held As Part Of The First National Fisheries Manager Conference Terrigal Nsw 21 September 1993, A. E. Magee

Fisheries Management Papers

General concern of all states was the actual AND potential impact of charter fishing on the resource and the inability to measure such impacts. The perceived problem with dual licensing was unregulated effort and the abilit to circumvent management controls. This paper provides current charter boat management arrangements in Australia, why they should be managed, types of charter vessels, Licensing, Management of recreational only charter vessels, Non-consumptive charters, Management guides and small scale charter operators, Commonwealth jurisdiction, Development of agreed strategies and Identification of future needs.

A Comparison Of No And N20 Production By The Autophic Nitrifier Nitrosomonas Europaea And The Heterotrophic Nitrifier Alcaligenes Faecalis, Iris C. Anderson, Mark Poth, Julie Homstead, David J. Burdige

OES Faculty Publications

Soil microorganisms are important sources of the nitrogen trace gases NO and N₂O for the atmosphere. Present evidence suggests that autotrophic nitrifiers such as Nitrosomonas europaea are the primary producers of NO and N₂O in aerobic soils, whereas denitrifiers such as Pseudomonas spp. or Alcaligenes spp. are responsible for most of the NO and N₂O emissions from anaerobic soils. It has been shown that Alcaligenes faecalis, a bacterium common in both soil and water, is capable of concomitant heterotrophic nitrification and denitrification. This study was undertaken to determine whether heterotrophic nitrification might be …

Bone As A Spring, Frank E. Fish

Biology Faculty Publications

No abstract provided.

The Direct Sensing Of Damage To Ion Implanted Materials, J. S. C. Mckee, M. S. Mathur, G. R. Smith

Scanning Microscopy

Material damage caused by the implantation of a high concentration of hydrogenic ions requires regular remote monitoring in order to study the atomic and nuclear reaction processes taking place within each sample. Real time continuous measurements of acoustic emission, X-ray production and emitted particle flux enable processes such as bubble or crack formation, changes in crystalline order, and nuclear fusion reactions can be studied in detail through examination of secondary or associated emission products. Fracturing of a material may generate a unique signature which, when taken in conjunction with time-averaged quantities such as changes in resistivity, surface strain, and induced …

Reduction Of Sunburn Damage To Skin By Topical Application Of Vitamin E Acetate Following Exposure To Ultraviolet B Radiation: Effect Of Delaying Application Or Of Reducing Concentration Of Vitamin E Acetate Applied, John R. Trevithick, David T. Shum, Sahle Redae, Kenneth P. Mitton, Christopher Norley, Stephen J. Karlik, Alan C. Groom, E. E. Schmidt

Scanning Microscopy

The skin of the skh-1 mouse after ultraviolet B (280-320 nm, UVB) irradiation shows the pathological changes typical of sunburn damage: spongiosis (edematous spaces) around some cells, necrosis of keratinocytes, giving rise to sunburn cells, inflammatory infiltration ofpolymorphonuclear leucocytes, etc. In our previous study, these were accompanied by erythema, increased skin sensitivity, and edematous swelling. The topical application of tocopherol acetate (TA) immediately after the UVB exposure decreased these changes. In this paper, multiple measurements of the skin thickness were made at different locations along the magnetic resonance imaging (MRI) cross-sectional image of the skin. This permits effects to be …

Atomic Force Microscopy Study Of Human Tooth Enamel Surfaces, Ph. Schaad, E. Paris, F. J. G. Cuisinier, J. -C. Voegel

Scanning Microscopy

Human enamel features from individual crystals up to prisms were observed by atomic force microscopy (AFM). Low magnification images of vestibular tooth surfaces show the existence of enamel prisms appearing as deep holes. Individual, parallel enamel crystals show lateral faces elongated and formed by the (100) planes of hydroxyapatite (HA). Height differences between (001) faces create the roughness of enamel surface. Individual (001) crystal faces can be observed clearly at higher magnification and show the characteristic hexagonal shape with 60° angles between (100) faces. This study confirms the applicability of AFM for studying biological hydroxyapatite crystals.

Biological Inventory, Natural History, And Human Impact Of Palo Alto National Battlefield, Norman L. Richard, Alfred T. Richardson

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Biology)

During 1993 a floral and fauna inventory was conducted on the Palo Alto National Battlefield Historic Site . Vegetational associations were mapped, and the impacts of agriculture and ranching were assessed. Attention was given to identifying endangered, threatened, or candidate species present within the site boundaries, and also species which may have been extirpated. An attempt has been made to envision where historic roadways were located and how the 1846 landscape may have appeared.