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Reply By A. Carretero Et Al., Ana Carretero, H. Ditrich, M. Navarro, H. Splechtna, J. Ruberte

Scanning Microscopy

Dear Editor,

The study of vascular casts in the embryo by means of the scanning electron microscope represents the main subject of our research. We fully agree with DeRuiter and Gittenberger-de Groot in that corrosion casting is a valuable tool to study the early angiogenesis in embryos.

Balancing Surface Energy Terms For Stable Growth Of Planar Surfaces, M. Albrecht, P. O. Hansson, S. Christiansen, W. Dorsch, H. P. Strunk, E. Bauser

Scanning Microscopy

We investigate the driving forces that determine the growth mode of heteroepitaxial Ge layers grown from solution on Si substrates with orientations (001), (011) and (111) by transmission electron microscopy (TEM) and atomic force microscopy (AFM). Using liquid phase epitaxy, we can study the influences of strain and surface energy terms independently on effects due to limited surface diffusion. In (001) and (011) orientated layers, {111} faceted islands form (Stranski-Krastanov growth). In contrast, (111) orientated layers grow in a two-dimensional step flow growth mode (Frank-van der Merwe growth).

We model these investigations in terms of energy minimisation considering surface energy …

Znse Heteroepitaxial Growth On Si (100) And Gaas (100), D. K. Biegelsen, R. D. Bringans, J. E. Northrup, L. -E. Swartz

Scanning Microscopy

The early stages of ZnSe heteroepitaxy on Si(100), Si(100):As and GaAs(100) are compared and contrasted, based on results of scanning tunneling microscopy and photoemission spectroscopy. High Se reactivity with the substrate constituents leads to bulk phase formation which is detrimental to heteroepitaxy. As-termination of Si(100) not only passivates the surface, but also provides an ideal buffer for ZnSe overgrowth. Lacking a similar buffer layer, stoichiometric control of the GaAs(100) surface is investigated to find a means for controlled heteroepitaxy.

Recent Surface Studies Using Biassed Secondary Electron Imaging, Rajendra Persaud, Hisato Noro, Muhammad Azim, Robert H. Milne, John A. Venables

Scanning Microscopy

The growth and surface diffusion of Cs on Si(100) and Ag on Fe(110) have been studied using biassed secondary electron imaging (b-SEI) and Auger electron spectroscopy (AES).

The b-SEI technique was found capable of detecting Cs on the Si surface with a 0.5% ML sensitivity. Unusual diffusion profiles containing linear sections were obtained for coverages (θ) < 1/2 ML. The general form of these profiles were reproduced using a 2-phase model, where Cs chains act as sources of mobile adatoms, in conjunction with a diffusion coefficient of the form D ~ θ (1- Cθ). This form of D, obtained from Boltzmann-Matano analysis, is consistent with diffusion theory including strongly repulsive Cs-Cs interactions. An adatom diffusion energy, E_d, = 0.47 ± 0.05 eV was found to be consistent with measurements …

Predicting Relaxation In Strained Epitaxial Layers, R. Beanland, D. J. Dunstan, P. J. Goodhew

Scanning Microscopy

Strained epitaxial semiconductor layers, much thicker than the critical thickness, have been used as "strain-relief" buffer layers for many years. The most successful structure developed so far dates back to the 1960's, and consists of a very thick ( ~30 μm) layer in which the misfit is gradually and continuously increased. These structures relax completely and have a sufficiently low threading dislocation density to allow a device structure to be grown on top. This process requires a very high growth rate to produce the buffer layer in a reasonable time, which is only provided by hydride vapourphase epitaxy. Recently, there …

New Applications Of The Nuclear Microprobe For Biological Samples, Jan Pallon, Klas Malmqvist

Scanning Microscopy

The continuing development of the Nuclear Microprobe (NMP) has opened up new fields of applications in biology and medicine. Quantitative multielemental analysis in small sections of samples can be performed routinely. The use of techniques such as scanning transmission ion microscopy makes imaging as well as mass normalization possible at submicron resolution. Recent medical applications include studies on thin cryosections prepared from autopsies and biopsies, as well as single cells grown directly on the backing foil used in the NMP analyses. The purpose of the single cell analysis is often pharmacological, e.g., testing of new drugs, their uptake and distribution. …

Daughter Cells Of Saccharomyces Cerevisiae From Old Mothers Display A Reduced Life Span, Nicanor Austriaco, Brian K. Kennedy, Leonard Guarente

Biology Faculty Publications

The yeast Saccharomyces cerevisiae typically divides asymmetrically to give a large mother cell and a smaller daughter cell. As mother cells become old, they enlarge and produce daughter cells that are larger than daughters derived from young mother cells. We found that occasional daughter cells were indistinguishable in size from their mothers, giving rise to a symmetric division. The frequency of symmetric divisions became greater as mother cells aged and reached a maximum occurrence of 30% in mothers undergoing their last cell division. Symmetric divisions occurred similarly in rad9 and ste12 mutants. Strikingly, daughters from old mothers, whether they arose …

Scanning Electron Microscopic Study Of The Collagen Sheath Of The Human Thyroid Gland And Its Disorders, Masao Morita, Takuro Ogata, Keijiro Araki

Scanning Microscopy

A cell-maceration/scanning electron microscope (SEM) method was employed to demonstrate the collagen sheath around follicles (perifollicular sheath) of the human thyroid gland and its disorders. In the normal thyroid gland, the follicles were surrounded by spherical collagen sheaths composed of a framework of thick collagen bands 1-5 μm in width and fine solitary collagen fibrils 50-70 nm in diameter. In benign thyroid diseases (Graves' disease, Hashimoto's thyroiditis and adenomatous goiter), the perifollicular sheaths differed in size and in shape according to the disease, but they were always composed of thick collagen bands and fine fibrils as in the normal thyroid. …

A Survey Of Source And Finished Water Supplies For Giardia Cysts And Cryptosporidium, Lisa Martin Sexton

Morehead State Theses and Dissertations

A thesis presented to the faculty of the College of Science and Technology at Morehead State University in partial fulfillment of the requirements for the Degree of Master of Science in Biology by Lisa Martin Sexton on December 1, 1994.

Isolation Of Three Hexahydro-1,3,5-Trinitro-1,3,5-Triazine- Degrading Species Of The Family Enterobacteriaceae From Nitramine Explosive-Contaminated Soil, Christopher Kitts, Daryl P. Cunningham, Pat J. Unkefer

Biological Sciences

Three species of the family Enterobacteriaceae that biochemically reduced hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) were isolated from nitramine explosive-contaminated soil. Two isolates, identified as Morganella morganii and Providencia rettgeri, completely transformed both RDX and the nitroso-RDX reduction intermediates. The third isolate, identified as Citrobacter freundii, partially transformed RDX and generated high concentrations of nitroso-RDX intermediates. All three isolates produced ¹⁴CO₂ from labeled RDX under O₂-depleted culture conditions. While all three isolates transformed HMX, only M. morganii transformed HMX in the presence of RDX.

Second Intermediate Host-Specificity Of Haematoloechus Complexus And Haematoloechus Medioplexus (Digenea: Haematoloechidae), Scott D. Snyder, John J. Janovy

Biology Faculty Publications

Second intermediate host-specificity was examined for two species of the frog lung fluke genus Haematoloechus. Nine species of freshwater arthropods were exposed to cercariae of H. complexus and H. medioplexus. Metacercariae of H. complexus developed in all arthropod species used. Metacercariae of H. medioplexus developed only in anisopteran odonate naiads. This difference in host utilization may have epizootiological implications. The potential development of H. complexus in a greater number of arthropods than H. medioplexus may increase the chances of ingestion of H. complexus by an anuran host. The range of arthropods parasitized by H. complexus indicates that host-specificity …

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.

Effect Of Lead On Flexor Muscle Contraction And Photochemically-Induced Platelet Aggregation In Pial Microcirculation Of The Mouse, Amna Hamad Al Dhaheri

Theses

Lead is one of many heavy metal ions that can effectively compete for the binding sites of calcium, block the calcium channels and disturb the ion exchange. As a result, lead would be expected to affect the calcium-mediated cell functions. Muscle contraction and platelet aggregation are two important functions in which Ca²⁺ plays a major role and ultimately are affected by lead. Experiments were carried out to investigate the effect of lead on mouse flexor muscle contraction and on photochemically-induced platelet aggregation in pial microcirculation. A study of an acute exposure (1, 5, 10 and 25 µM) and a …

The Religious Dimensions Of The Biological Narrative, Ursula W. Goodenough

Biology Faculty Research

A cell/molecular biologist challenges the thesis that science and religion are two ways of experiencing and interpreting the world and explores instead the possible ways that the modern biological worldview might serve as a resource for religious perspectives. Three concepts—meaning, valuation, and purpose—are argued to be central to the entire biological enterprise, and the continuation of this enterprise is regarded as a sacred religious trust.

This article was originally delivered at the Templeton Symposium,„Science and Religion: Two Ways of Experiencing and Interpreting the World”organized by Zygon: Journal of Religion and Science and the Chicago Center for Religion and Science, 31 …

Estrogen Induced Eosinophil Migration Into The August Rat Uterus Is Associated With Intercellular Adhesion Molecule Expression, Daniel R. Orcutt

Masters Theses

Estrogen causes an influx of eosinophils into the uterus in female rats. The diapedesis of eosinophils out of the vasculature has also been observed in allergic reactions, parasitic infections, and atopic dermatitis, and has been associated with cellular adhesion molecules (CAMs). Antibody blocking studies against ICAM-1/ LFA-1 and VCAM-1/VLA-4 have suggested that both ligand/receptor sets of CAMs are involved in the selective recruitment of eosinophils out of the vasculature. ICAM- 1 is expressed on the vascular endothelium and decreases in expression when IL-4 is introduced. VLA-4 is present on eosinophils and is suspected to allow selective migration of eosinophils out …

Formation And Structure Of Dentine In The Rat Incisor After Chronic Exposure To Sodium Fluoride, J. Appleton

Scanning Microscopy

Weanling rats were chronically exposed to sodium fluoride by feeding them for eight weeks with a standard powdered diet incorporating sodium fluoride at 0.025% , 0.05% and 0.1% by weight. After eight weeks blood was removed by cardiac puncture and the levels of plasma calcium and phosphate determined. The incisor teeth were removed and their structure examined in the scanning electron microscope (SEM) using backscattered electron imaging to determine the relative concentration and distribution of the mineral phase in the dentine. There was no significant alteration to the normal serum calcium and phosphate levels. Small scattered interglobular spaces were seen …

Cryo-Jet Preservation Of Calcium In The Rat Spinal Cord, William B. Greene, Lyle G. Walsh

Scanning Microscopy

In order to determine the distribution of diffusible ions, especially calcium, in rat spinal cord axons before and after trauma, sham, 6 hours post 6 gm/cm and 20 gm/cm trauma cords were cryo-jet frozen in situ and cryo-sections were subjected to electron probe X-ray microanalysis. The results confirm part of the Ca hypothesis, i.e., some spinal cord axons accumulate intracellular Ca after traumatic injury. In addition, 6 hours after trauma, Ca is only accumulated by axons that have also lost homeostasis. Thus, it is likely that observations of the continual rise of Ca in the traumatized spinal cord are due …

Investigations On Glycolipid Production By Pseudomonas Putida Grown On Toluene In Batch And Continuous Culture Conditions, Keith Foorest Dockery

Dissertations and Theses

Utilization of toluene by Pseudomonas putida as its sole carbon and energy source affects morphology, outer membrane protein composition, and glycolipid production. Two strains of P. putida were found to utilize toluene and to coexist in continuous and batch culture. The two strains were designated translucent and opaque, based upon their readily identifiable coloration when grown on Luria agar. The translucent strain was the dominant strain in continuous culture conditions. The outer membrane proteins of P. putida were separated by sodium dodecyl sulphate polyacrylamide gel electrophoresis. When toluene is the carbon and energy source, the trend in protein composition was …

Denitrification, Nutrient Regeneration And Carbon Mineralization In Sediments Of Galveston Bay, Texas, Usa, Andrew R. Zimmerman, Ronald Benner

Faculty Publications

Rates of benthic denitrification, oxygen consumption and nutrient regeneration were measured during winter, spring and summer in Galveston Bay (Texas, USA) sediments. Denitrification ranged from 0 to 47 µmol N₂ m^-2 h^-1 with maximal rates generally occurring in the summer and the upper estuary. Oxygen consumption rates ranged from 38 µmol O₂ m^-2 h^-1 in the winter to 353 µmol O₂ m^-2 h^-1 in the summer and were correlated with denitrification rates. Variations in bay water temperature accounted for 52 % of the variability associated with denitrification rates whereas only 28% …

Morphologic Changes Of Apoptosis Induced In Human Chronic Myelogenous Leukemia "Blast" Cells By Sc41661a (Searle), A Selective Inhibitor Of 5-Lipoxygenase, K. M. Anderson, T. M. Seed, J. Peng, A. Jajeh, J. Meng, J. E. Harris

Scanning Microscopy

Several inhibitors of the arachidonic acid-metabolizing enzyme, 5-lipoxygenase reduce proliferation of hematopoietic and non-hematopoietic cells and cell lines and some cells undergo limited differentiation. Cells were cultured from patients with chronic myelogenous leukemia in "blast" crisis with the selective inhibitor of 5-lipoxygenase,SC41661A[3-{3,5-bis(1,1-dimethyl)-4-hydroxyphenyl}hiol]-N-methyl-N-[2-(2-phridinyl-propanamide)]. Cells cultured for 3 to 5 days with 40 μM SC41661A exhibited reduced cellular numbers along with ultrastructural changes and DNA laddering characteristic of apoptosis. Similar culture conditions reduced proliferation of U937 monoblastoid cells. In U937 cells, the ultrastructural features of apoptosis were not observed at 72 hours, when DNA laddering was present and cell numbers were reduced, …

Urinary Glycosaminoglycans Are Selectively Included Into Calcium Oxalate Crystals Precipitated From Whole Human Urine, Koji Suzuki, Keiko Mayne, Ian R. Doyle, Rosemary L. Ryall

Scanning Microscopy

Urinary glycosaminoglycans are selectively included into calcium oxalate (CaOx) crystals precipitated from whole human urine: The presence of glycosaminoglycans (GAGs) in the organic matrix of urinary stones, and their known effects on CaOx crystallization have prompted speculation regarding their role in CaOx urolithiasis. The aim of this study was to examine the involvement of GAGs in the early stages of CaOx crystallization in human urine. Urine samples were collected from healthy men and CaOx crystallization was induced by the addition of a sodium oxalate load. The crystals were harvested and demineralized, and the GAG content of the resulting extract analysed …

Changes In Proteins Associated With Nitrogen Fixation And Iron Nutrition In The Marine Cyanobacterium Trichodesmium, Karen Marie Elardo

Dissertations and Theses

This investigation tested the hypothesis that iron, as a micronutrient, will affect proteins in Trichodesmium and therefore affect nitrogen fixation. Changes in proteins that are a result of iron enrichment were compared to naturally occurring diel changes. Alterations in the iron protein of nitrogenase were compared to nitrogen fixation rates using the acetylene reduction technique. The observed changes in proteins were compared in Trichodesmium colonies from the Caribbean Sea and the Sargasso Sea.

Trichodesmium colonies were monitored for protein and iron content over a diel period on two cruises. The changes in protein and iron content in Trichodesmium colonies were …

A Comparison Of Neutrophil Migration In The Mouse In Response To Infection With Three Species Of Trichinella, Jon Darin Prulhiere

Dissertations and Theses

The Genus Trichinella is currently thought to consist of 8 separate species. Several methods have been used to help differentiate these. In this study the ability of three of these species, T. spiralis, T. pseudospiralis, and T. sp. 3 to independently infect MRL++ mice was compared at 5, 7, 11, 18 and 20 days post infection (dpi) with the hope of discovering new distinguishing characteristics. Of interest was the development of inflammation through the accumulation of neutrophils associated with larvae of Trichinella in mouse skeletal muscle. This was evaluated with routine histological stains, endogenous peroxidase staining and immunohistochemical …

Bcl-2 And P53 Protein Expression In All Grades Of Astrocytomas, Robyn L. Castleberg

Capstone Research Projects

No abstract provided.

Functional Consequences Of Compartmentalization Of Synaptic Input, Melissa J. Coleman, Michael P. Nusbaum

WM Keck Science Faculty Papers

Intra-axonal recordings of stomatogastric nerve axon 1 (SNAX1) indicate that there are synaptic inputs onto the SNAX1 terminals in the stomatogastric ganglion (STG) of the crab Cancer borealis (Nusbaum et al., 1992b). To determine whether this synaptic input only influenced SNAX1 activity within the STG, we identified the SNAX1 soma in the commissural ganglion (CoG). We found that this neuron has a neuropilar arborization in the CoG and also receives synaptic inputs in this ganglion. Based on its soma location, we have renamed this neuron modulatory commissural neuron 1 (MCN1). While intracellular stimulation of MCN1soma and MCN1SNAX has the same …

Shark Bay World Heritage Area Draft Management Plan For Fish Resources, Fisheries Department Of Western Australia

Fisheries Management Papers

Shark Bay was inscribed on the World Heritage List in December 1991 on the basis of its natural values. The Department of Conservation and Land Management (CALM) is the management agency with responsibility for the oversight and development of management plans dealing with both the marine and terrestrial aspects of the World Heritage Area. This Draft plan deals with the management of fish resources in the Shark Bay World Heritage Area which are the responsibility of the Fisheries Department of Western Australia.

Cell Injury And Apoptosis, Andrejs Liepins, J. Omar Bustamante

Scanning Microscopy

Various forms of cellular injury, whether induced by immune effector cells, aberrant metabolic processes, chemotherapeutic drugs or temperature shifts, result in common morphological changes consisting of the formation and shedding of membrane vesicles from the injured cell surfaces, i.e., apoptosis. This dynamic cell surface membrane behavior appears to be dependent on the disruption of cytoplasmic microtubules. Concomitant with the altered cell surface morphology, certain physiological and biochemical events have been found to be associated with cell injury. These include changes in membrane permeability, elevated oxygen consumption rates and nuclear DNA fragmentation. However, it remains to be experimentally established which of …

Distribution Of Sodium, Magnesium, Chlorine, Calcium, Potassium, Phosphorus And Sulphur In Z-, I- And A-Bands In Mammalian Striated Muscle, Romuald Wróblewski, Lars Edström

Scanning Microscopy

The regularity of the striation of skeletal muscle offers a unique possibility to analyze different bands of the sarcomere in longitudinally cut semithin cryosections. The aim of the present study was to investigate the elemental content of the Z-, I- and A-bands within the sarcomere which may be related to the affinity of an element to different contractile elements and the water content in different bands. The highest potassium levels were found in the Z-band {802 mmol/kg dry weight (d.w.)} as compared to the I-band (697 mmol/kg d.w.) and the A-band (731 mmol/kg d.w.). The difference between A-band and Z-band, …

Effects Of Modulated Microwave And X-Ray Irradiation On The Activity And Distribution Of Ca2+-Atpase In Small Intestine Epithelial Cells, Z. Somosy, G. Thuróczy, G. J. Köteles, J. Kovács

Scanning Microscopy

The distribution and activity of Ca²⁺-ATPase were investigated by histochemical methods in small intestine epithelial cells of mice following total body 2450 MHz low frequency (16 Hz) microwave and X-ray irradiation. In the control animals, enzyme activities were found in the brush border and on lateral membranes, including junctional areas of the cells. The enzyme activity of lateral membranes was inhibited by quercetin, a specific inhibitor of Ca²⁺-ATPase.

Immediately after square modulated (16 Hz) 2450 MHz microwave irradiation at 1 mW/cm² power densities, we observed a decreased activity of Ca²⁺-ATPase on the lateral …

Investigation Of Touch-Sensitive Responses By Hyphae Of The Human Pathogenic Fungus Candida Albicans, N. A. R. Gow, T. H. S. Perera, J. Sherwood-Higham, G. W. Gooday, D. W. Gregory, D. Marshall

Scanning Microscopy

Candida albicans is a fungus that commonly infects the mucosal surface of humans. The hyphal growth form of this fungus may initiate the primary invasion of the host. Here we show that hyphae respond thigmotropically and morphologically to cues such as the presence of a surface, pores, grooves and ridges. Growth on some firm surfaces elicits a helical growth response. Hyphae follow grooves and ridges of inert substrates and penetrate pores of filtration membranes. Our in vitro experiments suggest that thigmotropism may enhance the ability of a hypha to invade epithelia of a host at sites of weakened integrity.