Biology Commons^™

Identification And Localization Of Three Classes Of Myosins In Pollen Tubes Of Lilium Longiflorum And Nicotiana Alata, D. D. Miller, Stylianos P. Scordilis, P. K. Hepler

Biological Sciences: Faculty Publications

The presence and localization of actin and myosin have been examined in pollen tubes of Lilium longiflorum and Nicotiana alata. Immunoblot analysis of pollen tube extracts with antibodies to actin, myosins IA and IB, myosin II, and myosin V reveals the presence of these contractile proteins. Immunofluorescence microscopy using various methods to preserve the pollen tubes; chemical fixation, rapid freeze fixation and freeze substitution (RF-FS) followed by rehydration or by embeddment in a methacrylate mixture, was performed to optimize preservation. Immunocytochemistry reaffirmed that actin is localized longitudinally in the active streaming lanes and near the cortical surface of the …

Oxygen Control Of The Bradyrhizobium Japonicum Hema Gene., Karen M. Page, Mary Lou Guerinot

Dartmouth Scholarship

The hemA gene of Bradyrhizobium japonicum, which encodes the first enzyme in the heme biosynthetic pathway, is regulated by oxygen. Up to ninefold induction of beta-galactosidase activity is seen when cultures of B. japonicum containing either a plasmid-encoded or a chromosomally integrated hemA-lacZ fusion are shifted to restricted aeration. The oxygen effect is mediated via the FixLJ two-component regulatory system, which regulates the expression of a number of genes involved in the nitrogen fixation process in response to low-oxygen conductions; oxygen induction is lost when the hemA-lacZ fusion is expressed in strains of B. japonicum carrying mutations in fixL or …

The Morphological Effects Of Two Antimicrobial Peptides, Hecate-1 And Melittin, On Escherichia Coli, William G. Henk, William J. Todd, Frederick M. Enright, Pamela S. Mitchell

Scanning Microscopy

The effects of the 26 amino acid, cationic, amphipathic, antibacterial peptide melittin and hecate-1, a 23 amino acid analog of it, on the gram negative bacterium Escherichia coli were investigated using scanning electron microscopy (SEM), transmission electron micros-copy (TEM), and freeze-fracture. Both peptides killed virtually all bacteria at the peptide concentration and cell density used. TEM and SEM revealed aggregates of bacteria entangled with material extruded from the bacterial surfaces. SEM revealed irregular bacterial surfaces with bleb-like projections. TEM and freeze-fracture indicate that the bacterial inner and outer membranes, as well as the peptidoglycan layer between, were extensively damaged. The …

Use Of Colloidal Gold And Neutron Activation In Correlative Microscopic Labeling And Label Quantitation, B. J. Darien, P. A. Sims, K. T. Kruse-Elliott, T. S. Homan, R. J. Cashwell, A. J. Cooley, R. M. Albrecht

Scanning Microscopy

Albumin was conjugated to 16 nm gold particles (Alb-Au16) and infused into anesthetized pigs to determine if plasma, tissue and bronchoalveolar lavage (BAL) fluid concentrations of gold could be quantitated by neutron activation (Au198). Additionally, transmission electron microscopy (TEM) of lung and liver samples was evaluated for sites of gold distribution and morphological changes. The minimum concentration of gold detected by neutron activation ranged between 1.4 and 1.9 ppb (ng/gm of sample). No gold was detected in the plasma of pigs prior to Alb-Au16 infusion, while mean post infusion concentrations were 1.037 ± 0.69 ppm (μg/gm plasma, ±SD). The concentrations …

Heterogeneous Nucleation Of Calcium Oxalate Crystals In Mammalian Urine, Saeed R. Khan

Scanning Microscopy

It is generally recognized that calcium oxalate crystal formation in urine is induced by heterogeneous nucleation. However, there is no consensus as to the nature of the nucleation substrate. Evidence is provided in this paper that membranous cellular degradation products are the most likely candidates because they: (1) are ubiquitous in urine and urinary stones; (2) are found in close association with crystal deposits in the kidneys; and (3) can induce nucleation of crystals from a meta-stable solution of calcium oxalate in vitro and metastable urine in vivo.

Imaging Of The Cytoplasmic Leaflet Of The Plasma Membrane By Atomic Force Microscopy, C. Le Grimellec, E. Lesniewska, M. -C. Giocondi, C. Cachia, J. P. Schreiber, J. P. Goudonnet

Scanning Microscopy

The cytoplasmic face of ventral cell membranes of Madin-Darby canine kidney (MDCK) cells grown on glass coverslips was imaged by atomic force microscopy (AFM) in air and under aqueous medium, in "contact" mode. Micrometer range scans on air-dried samples revealed a heterogeneous structure with some filaments, likely corresponding to actin filaments that abut the inner leaflet of the membrane, and a few semi-organized lattice structures that might correspond to clathrin lattices. Experiments in phosphate-buffered saline confirmed the heterogeneity of the inner membrane surface with the presence of large (> 100 nm) globular structures emerging from the surface. Using sub-micrometer scan …

Heterogeneous Distribution Of Ecto-Ca-Atpases In Primary Cultures Of Human Adenohypophyseal Cells, A. Kittel, I. Miklos, E. Bacsy

Scanning Microscopy

The aim of this study was to investigate the localization of ecto-Ca-adenosine-triphosphatase (ecto-Ca-ATPase) in different parenchymal cells of the human pituitary in tissue culture. The distribution of ecto-ATPases on the surface membrane of a particular parenchymal cell varied with the type of cells in contact with this parenchymal cell; the membrane portions immediately exposed to the medium showed low if any ecto-ATPase activity. These results suggest that ecto-Ca-ATPases of the parenchymal cells may be involved in cell adhesion processes and may be of crucial importance in the organization (in vivo) and reorganization (in vitro) of human …

Scanning Electron Microscope Study Of The Healing Molar Tooth Extraction Socket In The Rat, M. D. Mcmillan

Scanning Microscopy

Healing molar tooth extraction wounds in rats were examined by scanning electron microscopy from 15 minutes to 40 days following tooth removal. The wound epithelium, which was derived mainly from the gingiva but also from the cheek and hard palate, migrated be-neath the superficial socket contents. The contents were lost between 5 to 11 days, thus leaving a central epithelial-lined depression. This decreased in width with time as the level of the wound epithelium approached that of the hard palate but was still present at 40 days. Between 5 and 7 days, the wound epithelium became more regular. However, from …

The Interaction Of Laser Energy With Ureter Tissues In A Long Term Investigation, U. Stratmann, K. Schaarschmidt, R. R. Lehmann, A. Heinze, G. H. Willital, E. Unsold

Scanning Microscopy

This study investigates tissue responses after laser irradiation of the rabbit ureter, which serves as an experimental model for rectourogenital fistulae of children. Twenty-five rabbit ureters were irradiated intraluminally by a Nd:YAG laser 1320 nm (2 Watt, 20 seconds and 3 Watt, 8 seconds) via an applicator with radialsymmetrical light distribution. Immediately, 2 weeks, 4 weeks, 8 weeks, and 16 weeks after irradiation, the ureters were X-rayed with contrast solution and prepared for light and transmission electron microscopy. For the parameters employed, no apparent morphological differences could be observed. Immediately, the central laser zone showed a transmural therrnonecrosis prevailed by …

Imaging Of Single Antigens, Antibodies, And Specific Immunocomplex Formation By Scanning Force Microscopy, Arjan P. Quist, Anna A. Bergman, Curt T. Reimann, Sven O. Oscarsson, Bo U. R. Sundqvist

Scanning Microscopy

The most sensitive analytical techniques available today for detecting immuno assay complexes are radio or enzyme immuno analytical techniques, by which quantities of 10⁷-10⁸ analyte molecules can be detected. With the introduction of scanning force microscopy, a new method for detecting biological processes became available. Here, we examine the feasibility of using scanning force microscopy as a biosensitive tool. We demonstrate that single or multiple rabbit anti-human serum albumin molecules form complexes with preadsorbed single human serum albumin molecules on mica. However, no interaction is observed between human immunoglobulin G molecules and preadsorbed single albumin molecules; only …

Simulation Of Electron Emission From Beryllium Under Electron And Ion Bombardments, Kaoru Ohya, Jun Kawata

Scanning Microscopy

A Monte Carlo simulation model of particle-induced electron emission from beryllium, a candidate material for use on the wall in thermonuclear fusion devices, is developed. Comparative studies between secondary electron emission by electron bombardment and kinetic electron emission by proton bombardment reveal some interesting similarities and differences. The kinetic emission of electrons under heavy-ion bombardment is simulated as well for analyzing the effect of the initial charge state and mass of projectile ions on the kinetic emission. Furthermore, the model is applied to bowl-and-ripple structures for the study of surface roughness effects on the energy and angular distributions of secondary …

Dynamics Of Vortices In Superconductors Observed By Electron Waves, Akira Tonomura

Scanning Microscopy

Although, in electron microscopy, an object is usually observed by using the intensity of an electron beam transmitted through it, the phase distribution of the electron beam also provides different information about the object. It has been difficult, however, to obtain the phase information because of the low coherence of an electron beam. Recent development of a "coherent" field emission electron beam and related techniques, such as electron holography, has provided a way to observe microscopic objects and fields by precisely measuring the phase information of an electron beam. It has, for example, become possible to observe the dynamics of …

Scanning Force Microscopy Of Chromatin, Wolfgang Fritzsche, James Vesenka, Eric Henderson

Scanning Microscopy

Scanning force microscopy (SFM) is a new method to obtain the topography of surfaces with nanometer-resolution. The ability to image under liquids makes the technique attractive for biological applications, especially for the determination of the ultrastructure of biomolecules under native conditions. One growing field of interest is the investigation of chromatin and chromatin-related structures. Different levels of chromatin condensation were the subject of several previous SFM investigations, from the nucleosomal chain, to the 30-nm fiber, ending with the metaphase chromosome. The SFM yielded new information on such fundamental problems as the core spacing of the nucleosomal chain, the internal structure …

The Ampullae Of The Inner Ear In The Lizard Podarcis S. Sicula. Ultrastructural Aspects, G. Balsamo, B. Avallone, D. Calabro, F. Marmo

Scanning Microscopy

The inner ear ampullae of the lizard Podarcis s. sicula were studied to determine better the ultrastructure of ampullar epithelial cells.

Our study confirmed that the ampullae of the membranous labyrinth of this lizard are similar to those of other vertebrates in their ultrastructural aspect.

Moreover, our observations revealed a special type of dark cells, restricted to a small area of the crista. They appeared similar to type II sensory cells and showed a dark, finely granular cytoplasm, containing numerous mitochondria and ribosomes, extensive Golgi apparatus and abundant glycogen.

The morphology of these cells suggests that they may be …

Scanning Tunneling Microscopy Studies Of Chloroplasts In Solution, Douglas C. Dahn, Katrina Cake, T. Lynn Macdonald, Lawrence R. Hale

Scanning Microscopy

Previous work has shown that it is possible to image whole uncoated chloroplasts using scanning tunneling microscopy (STM), provided this is done in solution using tunnelling currents below about 100 pA.

More recent images include some which suggest that the STM is sensitive to dynamic processes occurring on chloroplast surfaces. Current-versus-distance curves and dI/ds measurements are consistent with tunnelling between the tip and sample surface, and relatively small deformations of the sample surface due to tip-sample forces. Attempts to use the same imaging conditions on bacteria were unsuccessful.

Mammalian Enamel Prism Patterns And Enamel Deposition Rates, Elizabeth R. Dumont

Scanning Microscopy

Enamel prism patterns and enamel deposition rates were compared for specimens representing six mammalian orders. Enamel samples were characterized by either pattern 1 or pattern 3 prisms. Each prism pattern cate-gory contained prisms from at least two mammalian orders. Enamel deposition rate was estimated for each sample by measuring prism cross striation repeat intervals. Statistical analysis of cross striation repeat intervals illustrates significant differences in deposition rate between prism patterns 1 and 3. No statistically significant differences were found in deposition rate between the higher-level taxa represented within each prism pat-tern category. That enamel deposition rate is not taxon-specific reinforces …

Low Concentrations Of Mercury Induce Changes In Ion Composition Of Cultured Myoblasts, Joanna Wroblewski, Jan Ekstrand, Romuald Wroblewski

Scanning Microscopy

The effects of low concentrations (1 pM, 1 nM, 1 μM) of mercuric chloride on ion distribution in cultured myoblasts were analysed by energy dispersive X-ray microanalysis. An increase in intracellular sodium concentration was observed five minutes after addition of HgC12 to the culture medium. This increase was dose dependent and accompanied by a transient decrease in potassium concentration. Exposure to 1 nM and 1 μM HgC12 led to a two-fold increase in the cytoplasmic chlorine concentration. The higher HgC12 concentration (1 μM) induced morphological alterations in the form of cell membrane blebs, perforations and shrinkage or flattening of the …

Cross-Linking Of Cell Surface Receptors As A Trigger Of Cell Apoptosis And Proliferation, Yuri N. Korystov

Scanning Microscopy

A hypothesis of the mechanism by which the protein cross-linking agents trigger apoptosis of lymphoid cells and proliferation of other cell types is proposed. It is assumed that both effects are triggered by aggregation of receptors on cell surface, which results from their cross-linking. This idea is substantiated by the example of one of these agents, ionizing radiation. As in the case of physiological agents, such as, antigens and growth factors, the aggregation of receptors induced by radiation activates receptor protein tyrosine kinases from which the signal is transduced to genes through protein kinase C. The hypothesis is consistent with …

From Scattering And Recoiling Spectrometry To Scattering And Recoiling Imaging, M. M. Sung, V. Bykov, A. Al-Bayati, C. Kim, S. S. Todorov, J. W. Rabalais

Scanning Microscopy

A new ion scattering technique, called scattering and recoiling imaging spectrometry (SARIS), is being developed. The SARIS technique uses a large, position sensitive microchannel plate (MCP) and time-of-flight methods to capture images of scattered and recoiled particles from a pulsed ke V ion beam. These images combine the advantage of atomic scale microscopy and spatial averaging simultaneously since they are created from a macroscopic surface area but they are directly related to the atomic arrangement of the surface. This paper de-scribes the basis of the SARIS technique, the instrument which is under development, and the scattering and recoiling …

Crystallographic Evidence For Dimerization Of Unliganded Tumor Necrosis Factor Receptor, James H. Naismith, Tracey Q. Devine, Barbara J. Brandhuber, Stephen R. Sprang

Biological Sciences Faculty Publications

Activation of the cell surface receptors for tumor necrosis factor (TNF) is effected by the aggregation of cytoplasmic domains that occurs when the extracellular domains of two or three receptors bind to trimeric TNFα or TNFβ. The structure of the type I TNF receptor extracellular domain (sTNF- R1), crystallized in the absence of TNF, has now been determined at 2.25-Å resolution. The receptor itself is an elongated molecule comprising four disulfide-rich domains in a nearly linear array. Contrary to expectations, the unliganded domains are found to associate into dimers of two distinct types, in which monomers are related by local …

Management Options (Discussion Paper) For The Shark Bay Snapper Limited Entry Fishery, Shark Bay Snapper Limited Entry Fishery Working Group, Doug Bathgate

Fisheries Management Papers

At the Annual Management Meeting of the Shark Bay Snapper Limited Entry Fishery held on 22 July 1994 industry put forward a proposal that supplementary and non-transferable quota that was "lost" to the fishery when a licence holding non-transferable quota was transferred should be retained by the Fisheries Department and leased back to licence holders on an annual basis. As a result of this proposal and the fact that the management arrangements for the fishery are extremely complex and in need of simplification, the Minster for Fisheries approved the establishment of a Working Group to examine the lease-back proposal and …

Management Of The Northern Demersal Scalefish Fishery, Jane Fowler

Fisheries Management Papers

In mid 1994, the Fisheries Department of Western Australia announced that it would prepare a discussion paper setting out options for future management of the demersal scalefish fishery off the Kimberley coast. This paper, which was to be the start of a wider consultative process, was also to include options for possible further development of the trap and line fisheries. This paper is only the first step in a process for developing formal long term management arrangements under the new fisheries legislation, the Fish Resources Management Act 1994. Its aim is to provide some background and to present some management …

Report On Future Management Options For The South West Trawl Limited Entry Fishery, South West Trawl Limited Entry Fishery Working Group

Fisheries Management Papers

As a result of community concern regarding trawling, the current management rules for the South West Trawl Limited Entry Fishery were finalised in February 1989 and the final plan was gazetted in October of that year. However, there was public disquiet about this trawling, and as a result of this disquiet, a research program was initiated by the Fisheries Department with funding received from both the Commonwealth and State Governments. The scientific report, "The impact of trawling for saucer scallops and western king prawns on the benthic communities in coastal waters off south-western Australia" by L J B Laurenson, P …

Effects Of Reproductive Mode On Demography And Life History In Arabis Fecunda (Brassicaceae), Peter Lesica, J. Stephen Shelly

Biological Sciences Faculty Publications

Life history theory predicts that trade-offs between growth and reproduction should be dictated by a population's mortality schedule. We tested this prediction with Arabis fecunda, a short-lived perennial that occurs in many different habitats in southwest Montana. Individuals produce either or both axillary or terminal inflorescences. Axillary-flowering plants are usually iteroparous and have smaller reproductive bouts, while terminal-flowering plants have larger reproductive bouts, and tend to be semelparous. We recorded size and fecundity of A. fecunda individuals from 1989 to 1993 in three different habitats. There was great variation in demographic and life history traits among the populations. A …

Static Forces And Moments Generated In The Insect Leg: Comparison Of A Three-Dimensional Musculo-Skeletal Computer Model With Experimental Measurements, Robert J. Full, Anna N. Ahn

All HMC Faculty Publications and Research

As a first step towards the integration of information on neural control, biomechanics and isolated muscle function, we constructed a three-dimensional musculo-skeletal model of the hind leg of the death-head cockroach Blaberus discoidalis. We tested the model by measuring the maximum force generated in vivo by the hind leg of the cockroach, the coxa-femur joint angle and the position of this leg during a behavior, wedging, that was likely to require maximum torque or moment production. The product of the maximum force of the leg and its moment arm yielded a measured coxa-femur joint moment for wedging behavior. The …

Differential Distribution Of D4 And D2 Dopamine Receptors In Rat Brain: An Autoradiographic Study Using [3H]Ym-09151-2 And [3H]Raclopride, Nancy C. Stratman

Masters Theses

Extrapyramidal side effects (EPS) are associated with most antipsychotics for the treatment of schizophrenia since these agents antagonize dopamine D₂ receptors in the nigrostriatal pathway, a brain system that regulates motor functions. Clozapine, an atypical antipsychotic agent in that it does not produce EPS, was found to be more selective for the D₄ than the D₂ receptor. The purpose of this study was to locate the D₄ receptor in rat brain by autoradiographic comparison studies with [³H]YM-09151-2, a D₂ , D₃, and D₄ radioligand, to [³H]raclopride, a D …

Vitamin E Deficiency As A Model Of Precocious Brain Aging: Assessment By X-Ray Microanalysis And Morphometry, Carlo Bertoni-Freddari, Patrizia Fattoretti, Ugo Caselli, Roberta Paoloni, William Meier-Ruge

Scanning Microscopy

Vitamin E (α-tocopherol) is a known biological antioxidant able to quench the lipid peroxidation chain and to protect the cellular structures (e.g., plasma membranes) from the attack of free radicals which are reported to play a primary role in aging. To assess whether the absence of α-tocopherol from the diet of young laboratory animals may be considered a reliable model of precocious brain aging, intracellular ionic content of brain cortex pyramidal cells, ultrastructural features of synaptic contact zones, synaptic mitochondria and perykarial mitochondria positive to the succlillc dehydrogenase (SDH) histochemical reaction with copper ferrocyanide have been investigated by X-ray microanalysis …

A High-Bandwidth Frequency-Domain Photon Migration Instrument For Clinical Use, Steen J. Madsen, Eric R. Anderson, Richard C. Haskell, Bruce J. Tromberg

All HMC Faculty Publications and Research

We have developed a high-bandwidth frequency-domain photon migration (FDPM) instrument which is capable of noninvasively determining the optical properties of biological tissues in near-real-time. This portable, inexpensive, diode-based instrument is unique in the sense that we employ direct diode laser modulation and avalanche photodiode detection. Diffusion models were used to extract the optical properties (absorption and transport scattering coefficients)of tissue-simulating solutions.from the 300 kHz to I GHz photon density wave data.

High Resolution Electron Microscopy Of The Interface Between Dental Calculus And Denture Resin, Yoshihiko Hayashi

Scanning Microscopy

Dental calculus may grow on the denture surface. In order to demonstrate the mechanism of deposition, the interface between calculus and denture resin was investigated using a high resolution electron microscope. Ultrathin sections were also used for electron diffraction of selected areas to reveal any mineral phase.

The mineral layers without mineralized bacteria adjacent to the denture surface revealed a marked variation in thickness and crystal shape. Three types of crystal shape were observed at the junction: needle-like, rod-like and plate-like crystals. High resolution electron microscopy (HREM) showed that both rod-like and plate-like crystals were an aggregation of fine crystallites. …

The Influence Of 5-Fluorouracil On The Endothelium In Small Arteries. An Electron Microscopic Study In Rabbits, M. Cwikiel, B. Zhang, J. Eskilsson, J. B. Wieslander, M. Albertsson

Scanning Microscopy

5-Fluorouracil (5-FU) is a widely used antineoplastic agent. 5-FU induced cardiotoxicity is a still relatively unknown side-effect of this drug. This phenomenon could be due to a direct cytotoxic effect on the endothelial cells. We tested this hypothesis in an experimental study in rabbits, by scanning or transmission electron microscopic evaluation of endothelium in small arteries (the central artery of the ear) after in vivo treatment with 5-FU. Both local and systemic effects of 5-FU on endothelium were studied 15, 30, 60 and 120 minutes after intra-arterial or intraperitoneal treatment. Perfusion fixation at physiological pressure and temperature was used in …