Digital Commons Network^™

Freeze Substitution And Low Temperature Embedding, B. Humbel, M. Müller

Scanning Electron Microscopy

The problems of conventional EM-preparation techniques based on chemical fixation may be overcome to a considerable extent by freeze substitution techniques. Although at present substitution cannot be performed at sufficiently low temperatures to prevent the recrystallization of vitrified aqueous specimens, thin sectioned biological samples show an improved information density. If freeze-substitution is combined with conventional embedding above 273 K (Epon/Araldite, Spurr's resin) the substituting organic solvent must contain stabilizing agents such as osmiumtetroxide, glutaraldehyde or uranylions. In combination with low temperature embedding procedures (Lowicryl) completely unfixed samples are obtained, which are suitable for immunolabelling and electron spectroscopic experiments. Water in …

Colloidal Gold Particles Detected On Highly Structured Surfaces Of Large Samples By Backscattered Electrons In The Scanning Electron Microscope, D. Studer, R. Hermann

Scanning Electron Microscopy

Colloidal gold labelled surface antigens on large, highly structured samples were unambiguously visualized at high magnification with backscattered electrons at 25 kV in a field emission scanning electron microscope (SEM). Secondary electron (SE) and backscattered electron (BSE) images of large and highly structured specimens are frequently disturbed by charging effects. By optimizing the thickness of the conducting carbon layer and the intensity of the incident electron beam, this problem can be overcome. The midgut of the lepidopteran larvae of Spodoptera litoralis was used as specimen. The activated 𝛿-endotoxin of Bacillus thuringiensis coupled to colloidal gold binds to the microvilli exposed …

To Resin Or Not To Resin In Immunocytochemistry, J. J. Wolosewick

Scanning Electron Microscopy

Hydrated resinless sections produced by a variety of methods (cryoultramicrotomy or polyethylene glycol techniques) appear to be excellent specimens for post-embedding immunocytochemistry at the electron microscopic level. A perplexing problem is the lack of apparent penetration throuqhout the section thickness of particulate probes such as ferritin or colloidal gold. This report draws attention to the possible causes for this phenomenon namely the size of the probe and the possible effects of fixation or processing. Smaller probes, gentler fixation or permeabilization procedures and increased incubation times all seem to be logical approaches to increasing penetration of immunoreagents into thick hydrated sections.

Immunocytochemical Labeling Of Enzymes In Low Temperature Embedded Plant Tissue: The Precursor Of Glyoxysomal Malate Dehydrogenase Is Located In The Cytosol Of Watermelon Cotyledon Cells, C. Sautter

Scanning Electron Microscopy

The Lowicryl-technique in combination with protein A gold was used in order to localize the precursor of glyoxysomal malate dehydrogenase in watermelon cotyledons. Preservation of the antigen was evaluated by a preembedding technique in isolated organelles. The glyoxysomal malate dehydrogenase was localized in tissue sections by a postembedding technique. Antigens of glyoxysomal malate dehydrogenase were found in the glyoxysomal matrix and in the cytosol, whereas the endoplasmic reticulum was completely free of labeling. Controls are presented by preimmunserum, by a serum against various proteins of the glyoxysomal membrane and by application of cycloheximide in order to inhibit translation at cytosolic …

Detection Of Small (5-15nm) Gold-Labelled Surface Antigens Using Backscattered Electrons, Paul Walther, Martin Müller

Scanning Electron Microscopy

The analysis of surface antigens by scanning electron microscopy represents a practicable alternative to replica techniques. It is generally observed that smaller markers provide for better labelling. In the SEM very small colloidal gold labels however are hardly discerned from contaminants or from surface structures of similar size. They are however unambiguously demonstrated by combining the surface information provided by the secondary electron signal and the material dependent signal provided by the backscattered electrons. A field emission SEM equipped with a highly sensitive single crystal backscattered electron detector allows the routine detection of 5 nm gold particles on biological surfaces. …

The Morphology Of Thin Metal Coatings Formed By Rotary Shadowing Biological Species In High Vacuum, J. A. Panitz

Scanning Electron Microscopy

Rotary Shadowing has been used to increase the image contrast of biological species observed during edge-projection imaging in the transmission electron microscope. In this imaging mode, biological species are adsorbed from aqueous solutions onto a highly curved substrate and viewed, over its edge, in a direction parallel to its surface. Since the substrate is not placed between a biological adsorbate and the photographic emulsion that records its image, any material can be used as a support (including high-Z metals and semiconductors). Binding to these technologically interesting materials is observed with unusual clarity and contrast, even at 200kV. Individual adsorbates and …

Plasma Membrane Antigens Detected By Replica Techniques, H. Hohenberg, W. Bohn, G. Rutter, K. Mannweiler

Scanning Electron Microscopy

Methods are introduced for in situ preparation of cell cultures grown on glass coverslips using the replica technique. Special equipment and handling procedures enabled us to prepare large-sized and stable replicas suitable for ultrastructural and immunocytochemical analysis of the different faces of the plasma membrane (PM): the extraplasmic surface (ES), the complementary extraplasmic (EF) and protoplasmic (PF) fracture face, and the protoplasmic surface (PS). Colloidal gold markers in combination with protein A and monospecific/monoclonal antibodies were used to identify virus-specific antigens at the ES of infected cells. Stereo replicas show a coincident location of gold-labeled virus antigens at the ES …

High Resolution Scanning Electron Microscopic Cytology - Specimen Preparation And Intracellular Structures Observed By Scanning Electron Microscopy, T. Inoué

Scanning Electron Microscopy

With the recent developments of the specimen preparation techniques, intracellular organization has been observed three-dimensionally by scanning electron microscopy (SEM). A suitable preparation method is the most important factor for observing intracellular structures at high resolution. Since intracellular structures are usually hidden in the cytoplasmic matrix, SEM observation of them is impossible merely by cracking the fixed cell. To remove the fixed cytoplasm, an osmic maceration technique is the most effective method which is applicable to almost all kinds of specimen preparation. In our laboratory, we developed some methods for observing intracellular structures. Those are the O-D-O method, the A-O-D-O …

Human Metaphase Chromosome Preparation For Scanning Electron Microscopy - A Consideration Of Inherent Problems, T. D. Allen, E. M. Jack, C. J. Harrison, D. Claugher, R. Harris

Scanning Electron Microscopy

Although the physical dimensions of chromosomes are such that they fall well within the spatial resolving power of scanning electron microscopes, results in the past have been disappointing. This is most likely due to limitations in preparative techniques, coupled with the initial necessity to separate the chromosomes from the remainder of the metaphase cell. Two approaches have been employed, a; to use a variety of isolation buffers which provide bulk chromosome preparations, b; to use metaphase spreads prepared essentially as for light microscopy and re-processed for SEM. In the former, wide variations in chromosome surface topography and fibre organisation arise …

Working At Higher Magnifications In Scanning Electron Microscopy With Secondary And Backscattered Electrons On Metal Coated Biological Specimens And Imaging Macromolecular Cell Membrane Structures, Klaus-Ruediger Peters

Scanning Electron Microscopy

Membrane structures of macromolecular dimensions were imaged with high resolution secondary electron type I (SE-I) signal contrasts on metal coated biological specimens. The quality of the surface information was strongly dependent on the signal used for microscopy and on the properties of metal films, i.e., thickness, continuity, structure and decoration effects. Films of 10 nm thickness produced so much type II electrons that identical images were obtained with the conventional SE-II and BSE-II signals. In such images, the type I SE signal was so low that only very weak contrasts were recognizable. If the films - continuous or discontinuous - …

Obituary - Edwin Wallace King, John C. Morse, T R. Adkins

Publications

Dr. E.W. King was a highly respected scientist and teacher whose enthusiasm for entomology and general biology has inspired students toward excellence in our discipline for more than 30 years. On December 10, 1984, Dr. King died suddenly of complications associated with cancer.

Preparation Of Cryosections For Biological Microanalysis, Karl Zierold

Scanning Electron Microscopy

The element distribution in biological cells and tissues can be revealed by electron probe microanalysis from ultrathin cryosections. In particular, the distribution of physiologically important and often mobile elements such as Na, Mg, P, S, Cl, K, and Ca can be studied in cryosections on an ultrastructural level. The cryopreparation technique required for this purpose consists of 1. cryofixation, 2. cryosectioning, 3. cryotransfer including freeze-drying and carbon coating if necessary, 4. energy dispersive X-ray microanalysis in a cold stage equipped scanning transmission electron microscope. The lateral analytical resolution of this method is less than 50 nm in freeze-dried ultrathin (about …

Problems Associated With The Preparation Of Cell Suspensions For X-Ray Microanalysis Highlighted By The Comparison Of Results With Those Obtained From Tissue Sections, A. Warley, M. D. Kendall, I. W. Morris

Scanning Electron Microscopy

Fully quantitative X-ray microanalysis of freeze dried frozen sections allowed the concentration of monovalent ions in the nuclei of mouse thymocytes in tissue sections to be compared with those from thymocytes which had been isolated by a simple preparation procedure. Isolated cells showed increased concentrations of Na and Cl. This was further investigated in the rat where the size of the thymus a 11 owed comparison between different isolation media using cells derived from the same animal. Use of autologous serum as the final suspending medium gave reproducible results, whereas with suspension in BSS, or 20% dextran the results were …

Immuno-Cytochemistry With Backscattered Electrons, D. Soligo, E. De Harven, M. T. Nava, G. Lambertenghi-Deliliers

Scanning Electron Microscopy

Some cytochemical reaction products are visible inside the cytoplasm of cells observed with the scanning electron microscope (SEM) using the backscattered electron imaging (BEI) mode. Methods can be utilized whenever they result in the deposition of heavy metal, like silver, lead or osmium at the sites of the enzymatic reaction.

More recently the BEI mode of the SEM has been demonstrated to improve the detection of immunogold labeled cell surface antigens. Colloidal gold particles, 40 to 15 nm in diameter can be efficiently used for immuno-specific labeling. Moreover, cytochemical reactions can be applied to previously immunogold labeled cells, therefore combining …

Consumption Of Aquatic Plants By The West Indian Manatee, Kay Etheridge, G. B. Rathbun, J. A. Powell, H. I. Kochman

Biology Faculty Publications

Because manatees (Trichechus manatus) are large aquatic herbivores they have often been considered as potential control agents for aquatic plants. Several problems are associated with this concept, and a major one has been the gap in knowledge concerning food consumption rates of manatees. We estimated food consumption by measuring chews per unit time, chews per amount of food consumed, and time spent chewing food. Data were collected on captive manatees of various sizes and used to construct regression equations that predict consumption rates based on body size. Time budget data were obtained by radiotelemetry of free-ranging animals. Estimates of …

Autumnal Bird Migration Over The Windward Caribbean Islands, Timothy C. Williams , '64

Biology Faculty Works

No abstract provided.

Community Ecology, Robert K. Rose, Elmer C. Birney

Biological Sciences Faculty Publications

COMMUNITIES with Microtus tend to be structurally simple, usually grasslands or tundra, and to have no more than two species of Microtus and rarely more than six species of small mammals. Microtus often dominates both numerically and in total small mammal biomass, especially at higher latitudes. The small mammal community is most influenced by Microtus through its fluctuations in density, and thus also in biomass, by its relatively high level of diurnal activity, and by its year-round activity. Other species of small mammals may be adversely affected because Microtus usually is larger and behaviorally dominant and also because the mere …

Surgical Sterilization Of Grass Carp (Ctenopharyngodon Idella Val.), David H. Clippinger

Retrospective Theses and Dissertations

In November, 1983, 93 sexually immature and 33 mature grass carp (Ctenopharyngodon idella Val.) were surgically sterilized by clipping the gonaduct or removing a section of the ovaries of testes through a ventral incision between the pelvic girdle and the vent. No mortality occurred from this procedure. After six months (May, 1984), 95.7% of the immature and 100% of the mature grass carp had at least some gonadal tissue regeneration. Fifty-nine percent of the immature fish regenerated a pathway for the eggs or milt to enter the environment. Artificial spawning of the mature female grass carp was 66.7% successful. Over …

Recruitment Patterns In Young French Grunts, Haemulon Flavolineatum (Family Haemulidae), At St. Croix, Virgin Islands., William N. Mcfarland, E. B. Brothers, John C. Ogden, Myra J. Shulman, E. L. Bermingham, N. M. Kotachian-Prentiss

Integrative Biology Faculty and Staff Publications

No abstract provided.

A Macrofaunal Survey Of Three Contrasting Habitats Of The Littoral Zone In Cedar Lake, Illinois, Laura L. Holt

Master's Theses

No abstract provided.

Seasonal Responses Of Filtration Rates To Temperature, Oxygen Availability, And Particle Concentration Of The Freshwater Clam, Musculium Partumeium (Say), Albert J. Burky, Richard B. Benjamin, Denis G. Conover, Jennifer Detrick

Biology Faculty Publications

Seasonal filtration rates of a pond population of the freshwater pisidiid clam, Musculium par­tumeium (Say), were assessed by measuring the clearance of 2.02 µ.m latex beads from suspension and expressed in terms of FR = a(AFDW}b where FR = filtration rate (ml H20 · hr- 1 ) , AFDW = mg ash-free dry weight of a whole clam and "a" and "b" are constants. The a-values ( = FR of a 1-mg AFDW clam} vary seasonally with the highest rates corresponding to periods of maximum growth and reproduction in the spring and fall. Changes in "b" reflect the influence of …

Breeding Biology Of The Great Crested Flycatcher, Myiarchus Crinitus, (Linnaeus) In Central Florida, Mark A. Kershner

Retrospective Theses and Dissertations

No abstract provided.

Metatherian Reproduction: Transitional Or Transcending?, Virginia Hayssen, R. C. Lacy, P. J. Parker

Biological Sciences: Faculty Publications

The major difference between metatherian and eutherian reproductive patterns is the relative apportionment of maternal resources to gestation versus lactation, not the total temporal and energetic investment in each reproductive attempt. Gestation accounts for an average of 12% of the time from conception to weaning in marsupials; in placental mammals it accounts for 56% of this period of development. Parental investment at birth is less in marsupials (litter weight averages 0.09% of female body mass) than in eutherians (average 15.5%), but total maternal effort is comparable in the two groups, since the litter weight at weaning is similar for metatherians …

Comparative Study Of Lactate Dehydrogenase Activity In Diving And Nondiving Reptiles, Dennis A. Baeyens, Deborah Bursey, Robert Rountree

Journal of the Arkansas Academy of Science

The properties of lactate dehydrogenase (LDH) were examined in two snake species and one turtle species. The snakes used in the study were the semi-aquatic Nerodia rhombifera and the terrestrial Elaphe obsoleta, while Pseudemys scripta represented the turtle species. Our purpose was to compare the LDH activity of nondiving reptiles (Nerodia and Elaphe) with that of the well established diver Pseudemys. The kinetic properties of LDH and its susceptibility to inhibition by elevated pyruvate concentrations were investigated in the brain and heart of the three species. Brain and heart were chosen because they are highly aerobic tissues and therefore should …

Repair Of Lethal Damage Induced In A Hamster X Amphibian Hybrid Tissue Culture Cell Line By Ultraviolet Light And Gamma Ray, Susan Kulp, Ann Page, H. Gaston Griggs

Journal of the Arkansas Academy of Science

A hybrid cell line was formed by fusing cells from two established vertebrate tissue culture cell lines (V79B1 hamster and A84 Xenopus), which were known to differ substantially in resistance to some radiation-induced lesions and in associated repair potential. Ultraviolet and gamma ray dose-survival relations were then determined and analyzed for the three cell lines, primarily to compare the radiosensitivity (Do dose) of the hybrid line with that of each parental line for each radiation. Further experimentation was conducted to determine the extent to which observed differences in these Do doses could be attributed to interactions of the combined parental …

Morfología Y Funciones Del Conducto De Müller De Chthonerpeton Indistinctum (Reinhardt Y Lutken, 1862) (Amphibia: Gymnophiona) En Relación Con Los Mecanismos Reproductivos De La Especie, Nibia Berois, Rafael O. De Sá

Biology Faculty Publications

El orden Gymnophiona comprende anfibios ápodos, ciegos, de hábitos cavícolas y acuáticos. Como consecuencia de estos hábitos resulta muy difícil su colecta, lo cual redunda en un escaso conocimiento de la biología del orden y sobre las relaciones filogenéticas del mismo.

Una de las características más particulares del grupo se refiere a la modalidad reproductora, ya que aproximadamente el 50% de las especies presentan viviparidad y la totalidad de ellas tienen fecundación interna. Es por esta razón que el estudio del aparato reproductor ha sido encarado por diversos autores, en especial por Wake (1968, J. Morphol. 126: 291) con una …

Corticocortical Projections Of A Visually Responsive Area In The Cat Brain, Joseph Mcgrath

Journal of the Arkansas Academy of Science

The Clare-Bishop (CB) area bears the name of the investigators who first (1954) demonstrated a cortical area in the cat brain located along the lateral aspect of the middle suprasylvian gyrus which responded electrophysiologically to both optic nerve and striate cortex (area 17) stimulation. More recent studies of CB or the lateral suprasylvian (LS) area have supported its role in visual and/or oculomotor functions. Silver degeneration methods were undertaken to clarify some of the corticocortical connections of this cortical region. The data accumulated provides a morphological basis in support of the CB area's role in visual and/or oculomotor activities

Description Of The Form Of Wing-Flashing Behavior In Northern Mockingbirds (Mimus Polyglottos), Lyn M. Harper, Kathryn J. Schneider

Honors Theses

The purpose of this study was to describe the form and location of wing-flashing behavior in mockingbirds and to identify differences in flashing between young and adult birds through film analysis techniques and observation. Subjects consisted of 50 mockingbirds from the University of Richmond campus. Analyses of the data suggested that there were three types of wing-flashes based on degree of wing extension. Flashes were most likely to occur in direct sunlight and in grass. No significant differences in the form of flashes between adult and juvenile mockingbirds were found. It is hoped that this study will provide insight into …

The Effect Of Bilateral Adrenalectomy On The Electrocardiogram Of Meriones Unguiculatus, Jeff A. Brown

Honors Theses

The effects of adrenalectomy on the heart rate and electrical potentials of the heart of the Mongolian gerbil were studied (using an EKG) in an attempt to determine in hyperkalemia is the cause of its short survival time following adrenal ablation.

The Distribution Of The Ctenophore, Mnemiopsis Leidyi (A. Agassiz), In A Vertical Thermal Gradient, James J. Leder Iii

Honors Theses

The distribution of organisms in an estuary is affected by a plethora of environmental factors. The ctenophore, Mnemiopsis leidyi, is found to exists over a wide range of these factors, temperature and salinity in particular, allowing it to occupy the estuary year round and make use of low salinity areas unavailable to most marine organisms.