Biology Commons^™

A Stimulus Timing Device For Capturing Fast Physiologic Events By Quick-Freezing, R. Nassar, J. R. Sommer

Scanning Microscopy

A timing device was designed that, in conjunction with an impact type of quick-freezing apparatus and an externally-triggerable stimulus generator, allows the application of an electrical stimulus to a muscle preparation at a selected time interval before quick-freezing and the measurement of the interval with submillisecond precision. This is needed for stopping fast physiological events in calcium release and excitation-contraction coupling and allows studying the morphological parameters (by freeze-fracture and freeze-substitution) and elemental distributions (by x-ray microanalysis) as a function of time after stimulation. The device should be adaptable for use with most equipment designed for quick-freezing electrically excitable tissue …

Histochemical Demonstration And Microanalysis Of Possible Calcium Binding Sites In The Enamel Organ Of Rat Incisors, Y. Takano

Scanning Microscopy

The rat incisors obtained from rats perfused with high-calcium solution containing 30 to 50 mM CaCl₂ were processed for rapid freeze/freeze-substitution and embedded in epoxy resin. GBHA staining, a histochemical staining for calcium, of unhydrously prepared sections revealed a large number of granular Ca-GBHA reactions in the enamel organ, most of which being located along the lateral plasma membranes of the ameloblasts. In the ameloblast layer, the reaction was negative in the presecretory stage, became intense in concert with the onset of enamel matrix formation, and remained so by the end of the transitional stage where the reaction gradually …

Coherent Strain And Clustering In Ge/Si Heteroepitaxy, Jeff Drucker

Scanning Microscopy

The Ge/Si heteroepitaxial system grows in the Stranski-Krastanov (layer + island) growth mode with an equilibrium intermediate layer thickness of 3 monolayers. Initially, coherent (dislocation free) islands form above the intermediate layer. These coherent islands relieve part of their lattice mismatch by elastic deformation of the layer + island + substrate system. After cluster growth, these islands may reach a critical radius above which it becomes energetically favorable for strain relief through the introduction of misfit dislocations. Particle size distributions generated from digitally acquired secondary electron images of Ge/Si(100) films grown in situ in an ultra-high scanning transmission electron microscope …

An Approach To Solid Phase Identification In A Ca-S-O System By Quantitative Energy Dispersive X-Ray Microanalysis, K. Wieczorek-Ciurowa, S. J. Sivonen, P. Kokkonen

Scanning Microscopy

Solid phases formed in the limestone sulphation reaction were identified by scanning electron microscopy with backscattered electron (BSE) imaging and by quantitative energy dispersive X-ray (EDX) microanalysis of calcium and sulphur. Since calcium and sulphur can form several compounds in the Ca-S-O system, two quantities, the sum of oxides (CaO+SO₃) and the molar ratio (CaO/SO₃), were used to calculate empirical formulae for the compounds actually present.

A method for analysing the experimental results is proposed, the mathematical expressions employed are presented and the numerical coefficients tabulated. It is shown with some examples that the method used …

Functional And Morphological Studies Of Mitochondria Exposed To Undecagold Clusters: Biologic Surfaces Labeling With Gold Clusters, E. Valdivia, C. Gabel, J. E. Reardon, C. A. Cajacob, H. Yang, R. S. Wehbi, G. L. Scott, P. A. Frey, L. A. Fahien

Scanning Microscopy

This study reports morphological and functional alterations observed in respiring isolated mitochondria when they are exposed to nonpenetrating, positive electrostatically charged synthetic undecagold clusters. Modification of the undecagold clusters positive charges change or prevent the functional effects and the binding to the outside surface of the mitochondria. The mitochondrial functional alterations are dependent on the oxidative phosphorylation capacity of the isolated organelles. The results of these experiments indicate that artificial undecagold may be useful to explore the molecular mechanisms of biological energy transducers which require electric charges separation, ionic fluxes, and electric surface properties.

Scanning X-Ray Microanalysis Of Microcarrier Cultured Endothelial Cells: Elemental Changes During The Transition To Confluency And The Effect Of Ionophore A23187, S. R. Hall, D. C. Sigee, J. E. Beesley

Scanning Microscopy

Porcine endothelial cells were grown on microcarrier beads and examined by scanning electron microscopy (SEM) at various times after initiation of culture. Total cell coverage on the bead surface varied from mean values of approximately 7% (3h) to 80% (96h). Beam penetration into the subcellular matrix presents a major problem with SEM X-ray microanalysis of microcarrier cultured cells and necessitates the use of an accelerating voltage not exceeding 10kV. At this voltage and below, X-ray contribution from elements present in the microcarrier bead has minimal effect on the determination of cell elemental levels. Washing the cells with 0.15M sucrose was …

Application Of Cathodoluminescence In Paint Analysis, W. Stoecklein, R. Göbel

Scanning Microscopy

When solving cases of burglary or investigating ship collisions, the forensic scientist frequently has to examine several layers of paint of the same color, often white. As a rule, the usual microscopic and spectroscopic methods [fluorescence microscopy, FT-IR (Fourier Transform Infrared Spectroscopy), pyrolysis, GC/MS (Gas Chromatography - Mass Spectrometry), etc.] are not sufficient to prove that the paint traces found on the scene, which are often only available in the form of fragments, originated from the same source as the reference material. It is possible to achieve convincing proof of this using either an optical cathodoluminescence-microscope or a cathodoluminescence-scanning electron …

On A Nature Of Cathodoluminescence Contrast Of Fine-Dispersed Structures In The Scanning Electron Microscope, M. V. Viskov, S. K. Obyden, G. V. Saparin

Scanning Microscopy

Fine-dispersed structures (FDS) consisting of a large number of microcrystalline or amorphous particles of different sizes and shapes were examined in cathodoluminescence (CL) mode scanning electron microscopy (SEM). Line dimension of each particle (about 10 - 100 μm) was larger than the electron beam diameter as well as electron scattering volume in material under investigation. An analysis of observed images showed the existence of some peculiarities in contrast which have not been observed in the CL-images for solid specimens. The FDS CL-image topographic contrast arises as a result of detection of CL-emission from an aggregate of FDS-elements surrounding an irradiated …

Electron Beam Induced Capacitance, O. V. Kononchuk, Eu. B. Yakimov

Scanning Microscopy

A model of signal formation in the Electron Beam Induced Capacitance (EBICap) mode of the Scanning Electron Microscopy (SEM) is proposed. In the frame of this model the possibilities of this technique are analyzed. It is shown that EBICap is suitable to obtain a local depletion region width and for mapping of this parameter. Experimental results demonstrating the potentialities of EBICap are presented.

Enamel Structure In Astrapotheres And Its Functional Implications, John M. Rensberger, Hans Ulrich Pfretzschner

Scanning Microscopy

Astrapotheres, large extinct ungulates of South America, share with rhinoceroses vertical prism decussation in the cheek tooth enamel. The similarity extends beyond merely the direction of the planes of decussation. The vertical decussation in astrapotheres is confined to the inner part of the enamel and has uniformly well-defined zones in which the prism direction differs by nearly 90° and the zones are separated by narrow transitional borders of intermediate prism direction. The outer enamel consists of predominantly occlusally and outwardly directed prisms. Within the outer enamel is a region of horizontally decussating prisms; here the angle of decussation is usually …

Mechanisms Of Ciliary Movement: Contributions From Electron Microscopy, Peter Satir

Scanning Microscopy

A brief review of important contributions of electron microscopy to the study of ciliary motility is presented. The electron microscope was used to show the universality of axonemal structure of cilia, and to develop the sliding microtubule model of ciliary motility and later the switch point hypothesis to explain the conversion of sliding into bending. Unexpectedly, insights into the importance of cilia in human health have stemmed from these studies.

Microwear And Striae Of Retzius Of Canines Of The Wild Japanese Monkeys (Macaca Fuscata), Teruyuki Hojo

Scanning Microscopy

This is a description of microwear and striae of Retzius of canine teeth of wild-caught female Japanese monkeys (Macaca fuscata) from Oita Takasakiyama, Kyushu. Micrographs were taken of high resolution casts using a scanning electron microscope (SEM). Before the casts were made, the diet of the captive monkeys was water-softened for three or four days. This softened diet probably added little wear to the surfaces of the teeth. These animals are part of a sample used in a previous report published in this journal. Others have observed that wild Japanese monkeys eat hard foods (such as grasshoppers, cicads …

Early Effects On The Morphology Of Mouse Small Intestine Of Single Or Combined Modality Treatment With Hyperthermia And X-Irradiation, G. R. Dickson, H. M. H. Kamel, S. P. Hume, M. Jaber, K. E. Carr

Scanning Microscopy

This study describes the effects of hyperthermia and X-irradiation on the morphological appearance of normal, at risk tissues in the ileum of the mouse. The early morphological effects day after a combined modality treatment are compared with those due to either hyperthermia or X-irradiation given alone. The response was assessed qualitatively and semiquantitatively using scanning electron microscopy and a villous scoring technique.

Early post-irradiation effects on topography did not differ significantly from those observed after small intestine exteriorisation without treatment. The villous scores for the combined modality treatments reflected greater damage than would be expected from the sum of villous …

A Preparation Protocol For Postembedding Immunoelectron Microscopy Of Dictyostelium Discoideum Cells With Monoclonal Antibodies, Bruno M. Humbel, Elke Biegelmann

Scanning Microscopy

On-section-labelling of Dictyostelium discoideum cells poses severe problems in retaining adequate morphology and antigenicity. Monoclonal antibodies are an essential tool in biochemistry and molecular biology because of their specificity and low. background staining. Unfortunately their advantage, the recognition of only one distinct epitope, is often a handicap for immunoelectron microscopy. Resin embedding and steric hindrance of the gold-tagged secondary antibodies further reduce the efficiency in detecting antigens making the localization of less abundant antigens difficult if not impossible. A successful preparation protocol should retain morphology and antigenicity, allow the antibodies easy access to the antigen and use a detection system …

Three-Dimensional Characterization Of Dense Bodies In Contracted And Relaxed Mesenteric Artery Smooth Muscle Cells, Linda J. Mcguffee, Sally A. Little

Scanning Microscopy

We have previously shown that dense bodies are not the static planar simple ovoidal structures they appear to be in thin sections. In this report, we present three-dimensional reconstructions from consecutive serial thin sections through shortened and non-shortened large mesenteric artery cells. Profiles of the cell surface, membrane dense bodies, and cytoplasmic dense bodies were reconstructed from consecutive thin sections and the distribution, size, shape, and spatial relationships among these components was examined. Within the cell, membrane dense bodies are numerous and occupy approximately 10% of the cell volume. Membrane dense bodies can attach to the cell surface laterally, obliquely …

Review And New Case Reports On Scanning Electron Microscopy Of Pili Annulati, Monilethrix And Trichothiodystrophy, K. Meyvisch, M. Song, N. Dourov

Scanning Microscopy

Pili annulati, Monilethrix and Trichothiodystrophy are uncommon conditions in which the hair shaft has a distinct appearance as seen by optical microscopy and scanning electron microscopy (SEM). We report several new cases and review the characteristic ultrastructural abnormalities investigated by SEM.

Pili annulati: abnormal areas which show a longitudinal, "curtain-like" folding of the cuticular cells, alternating with normal areas. The latter present regularly non-systematized, superficial depressions. Hair specimens of the patient's mother show the same surface irregularities.

Monilethrix: most hair shafts show variations in thickness giving a typical nodal appearance. In the isthmus area we noticed longitudinal ridging …

Cryofixation Of Tissues For Electron Microscopy: A Review Of Plunge Cooling Methods, Keith P. Ryan

Scanning Microscopy

This review of cryofixation by plunge cooling surveys liquid coolants, plunge cooling devices, modeling and applications featuring time resolution. It then focuses on thermocouple experiments and ice crystal analyses. These highlight the effects of the design of specimen holders, the cold gas above the coolant which can freeze the specimen prematurely, specimen size, plunge velocity, coolant depth and ultimate coolant efficiencies. The ice crystal cavity analyses are validated by experiments which monitor the effects of high subzero temperatures on the storage of plunge cooled specimens and an experiment which monitored the rate of cryosubstitution. Ethane was found to be more …

Scanning Electron Microscopy Of The Mammalian Organ Of Corti: Assessment Of Preparative Procedures, A. Forge, G. Nevill, G. Zajic, A. Wright

Scanning Microscopy

Different fixation, drying and coating procedures have been applied in preparation of the organ of Corti for scanning electron microscopy (SEM), and structural features of the apical surface of the tissue in unfixed, freeze-fractured preparations used in assessing their effects on morphology. Fixation with glutaraldehyde alone or osmium tetroxide alone causes artefacts that are substantially avoided when tissue is doubly fixed in glutaraldehyde followed by osmium. Significant improvements in preservation are also obtained when tissue is additionally processed through thiocarbohydrazide-osmium (TOTO) processing. In addition to providing a conducting coat, it stabilises the tissue against deformations that might otherwise occur during …

Scanning Electron Microscopic Studies Of The Oral Mucosa And Its Microvasculature: A Review Of The Palatine Mucosa And Its Microvascular Architecture In Mammals, Y. Ohta, S. Okada, I. Toda, H. Ike

Scanning Microscopy

The present paper deals with the microvascular architecture of the palatine mucosa in primates, camivorae, and rodentia utilizing microvascular corrosion castings and epithelium-separated specimens.

The submucous vascular network is under-developed since the bard palatine mucosa was designated the mucoperiosteum, except some areas. The palatine venous plexus appears to show regional differences with animal species differences. The well-developed plexus is observed to be two-layered and may contribute to the process of regurgitation of rough food and assist in mastication with the palatine plicae. Formation and patterns of the arterial network in the lamina propria are in a close relation with connective …

The Use Of Organ Cultures To Study Vessel Wall Pathobiology, Edward W. Y. Koo, Avrum I. Gotlieb

Scanning Microscopy

Organ culture of the vessel wall is an useful in vitro method to study vascular cell biology. The intact vessel allows for the study of cell-cell and cell-substratum interactions including the structure and function of the vessel wall matrix. Long term organ cultures of porcine aorta show that neointimal formation is due primarily to cell proliferation of pre-existing intimal smooth muscle cells. Neointimal formation in these cultures is more pronounced in the presence of an endothelium that is turning over. In endothelial wound repair studies, the endothelium of the organ culture shows some important differences when compared to tissue culture …

Off-Line Data Evaluation Of Elemental Maps Obtained From Scanning Nuclear Microprobe Analyses, N. E. G. Lövestam, E. Swietlicki

Scanning Microscopy

The results of scanning nuclear microprobe (SNM) analyses are normally presented as elemental maps showing the number of detector events, acquired within a certain energy region, for every pixel irradiated. Such elemental maps can be misleading if they are interpreted as directly reflecting the variations in the elemental concentrations across the analysed sample. The aim of this paper is to demonstrate how such elemental maps can be treated in order to facilitate the interpretation and extract the information contained in the data set, such as the covariation between elements. Examples of sample thickness correction, image processing and spectrum filtering as …

Detection Of X-Ray Damage Repair By The Immediate Versus Delayed Plating Technique Is Dependent On Cell Shape And Cell Concentration, Nandanuri M. S. Reddy, Maria Kapiszewska, Christopher S. Lange

Scanning Microscopy

A method commonly used to measure the ability of cells to repair potentially lethal damage (PLD) is to compare immediate plating (IP) and delayed plating (DP) survival. Lower cell survival under IP conditions relative to that after DP conditions has been interpreted to indicate a higher ability of cells to repair potentially lethal damage (PLO) under DP conditions. However, this IP radiosensitization has not been observed in several cell lines and tumor models. IP conditions involve treatment of cells with trypsin and plating them into fresh growth medium. We have investigated the possibility that radiosensitization under IP conditions may be …

Structure Of Rat Kidneys Following Microwave Accelerated Fixation, Jayashree A. Gokhale, Saeed R. Khan

Scanning Microscopy

In contrast to fixation of tissue in externally heated fixative, microwave-irradiation can generate uniform internal heat, which is of utmost importance for successful fixation of biological tissue. To evaluate the effectiveness of microwave-accelerated chemical fixation, we compared the structure of rat kidney fixed by a conventional method and a microwave-accelerated method, by scanning and transmission electron microscopy. Following perfusion, rat kidney pieces 1-2 mm in size were irradiated in Karnovsky's fixative in a domestic Amana microwave oven, till the temperature of the fixative reached 45-50°C. For conventional fixation, tissue pieces were fixed overnight at room temperature in the same fixative. …

Silicified Mississippian Paleosol Microstructures: Evidence For Ancient Microbial-Soil Associations, Ray Kenny, David H. Krinsley

Scanning Microscopy

Silica-replaced microfeatures in a well-developed, Upper Mississippian paleosol from north-central Arizona, were examined by scanning electron microscopy using back-scattered electron imagery. Preserved microfeatures include hollow and solid tubiform filaments and mycelium-like stringers which radiate from problematic (biogenic?) soil structures. Preservation of these features suggest that microstructures in the soil zone are not uniformly destroyed during post-diagenetic silica replacement and that biological soil symbionts may have occurred as early as the Upper Mississippian (~280 Mya).

Scanning Electron Microscopy Of A Soil Fungus Gliocladium Roseum, David Jones, Derek Vaughan, William J. Mchardy

Scanning Microscopy

The paper describes the ultra-structural features of cryofixed and critical point-dried sporing cultures of a soil fungus Gliocladium roseum. Features described are Acrostalagmus-like conidiophores with spore masses in mucoid balls borne at the tips of branchlets and penicillate heads with conidia massed in rope-like formations. A particular feature of the aerial hyphae and conidiophores is the presence of blister-like swellings on their walls. These observations help to accurately characterize the organism in taxonomic studies.

The Diagnostic And Phylogenetic Significance Of Widened And Pronged Hamuli In Feathers, Tim G. Brom, Uri Frank

Scanning Microscopy

The taxonomic distribution of widened and/or pronged hamuli (hooklets) on distal barbules in the pennaceous part of feathers was studied with light microscopy (LM) and scanning electron microscopy (SEM) in order to assess the diagnostic and phylogenetic significance of these structures. Comparison of the LM and SEM appearance of these structures indicates that "thickened" hamuli are artifacts, arising from the misinterpretation of rotated tape-like structures. Pronged hamuli, on the contrary, are non-artifacts. These structures have a much wider taxonomic distribution than was reported by earlier workers, and therefore do not seem to be useful for identifying feather fragments.

Augmentation Of Natural Populations Of Entomophagous Insects Through The Use Of Secondary Food Sources, John Swallow

Undergraduate Honors Capstone Projects

Local densities of predators, including ladybeetles, parasitoids, big-eyed bugs, and minute pirate bugs, increased with the application of artificial honeydew, consisted of sugar and wheast dissolved in water. Sugar, rather than wheast, was the active ingredient causing predators to aggregate, although wheast prolonged the effect of the sugar treatment for the ladybeetles. Furthermore, the artificial honeydew treatments had a marked effect for a period of one week. These results suggest a potentially important role of the use of synthetic honeydew as a means of pest control in an Integrated Pest Management system.

Circulating Antibodies To Thymic Antigens In Autism And Alzheimer's Disease, Chih-Li Chen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Abnormal T lymphocyte reactions in both autism and Alzheimer's disease (AD) have been reported. This research investigated the possibility that these abnormalities may involve circulating antithymic antibodies. Plasma samples from autistic patients, AD patients, and normal-matched controls were tested for reactivity against murine thymocytes.

In the first of 3 studies results of the enzyme-linked immunosorbent assay (ELISA) were statistically significant for binding (P < 0.001) between antithymic antibodies in plasmas of AD patients and murine thymocytes. Binding (P < 0.05) in low dilutions (1/2.5 and 1/5} of autistic patient plasmas was also observed. In the second study, plasmas of neither autistic nor AD patients significantly inhibited DNA synthesis of thymic cells in the presence of interleukin-1 (IL-l} and phytohemagglutinin (PHA). In the third study, no significant increases (P > 0.05) in cytotoxic activities were detected using AD patient plasmas and both untreated and heat-treated autistic patient plasmas. After further testing, these heat-treated plasmas diluted 1/64 and 1/128 had increased cytotoxicities (P < 0.05) when rabbit complement was added, an indication that cytotoxicity of antithymic antibodies is complement dependent.

Therefore, circulating antithymic antibodies may …

Biosystematics Of Seven Species Of Stipa From Southwestern United States And Northern Mexico, Penelope S. Hoge

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Two previously unidentified taxa of Stipa L. were evaluated morphologically, electrophoretically, and ecologically. The two 'new' taxa (tentatively referred to as "puzzlei" and "valdesii") were compared with five species from southwestern United States and northern Mexico (Stipa lobata Swallen, Stipa alta Swallen, Stipa scribneri Vasey, Stipa lettermanii Vasey, and Stipa nelsonii Scribner), all of which are considered to belong in the Achnatherum species-group. Anatomical and micromorphological features show that the 'new' taxa also belong in this species-group. Principal coordinate analyses of the morphological data showed that each of the seven taxa tended to occupy a …

The Influence Of Dietary Factors On The Risk Of Urinary Stone Formation, A. Hesse, R. Siener, H. Heynck, A. Jahnen

Scanning Microscopy

The action of various beverages and foods on the composition of the urine in the circadian rhythm and in the 24-hour urine has been investigated under standardized conditions. Orange juice leads to a significant increase of urinary pH and citric acid excretion. Black tea leads to a raised excretion of oxalic acid by only 7.9%. In the short term, beer increases diuresis, but afterwards leads to a compensatory antidiuresis with increased risk of stone formation. Depending on their composition, mineral waters have very different effects on the urinary constituents. Milk as well as cocoa beverage significantly increase calcium excretion; moreover, …