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Overlapping Transcription By Rna Polymerases Ii And Iii Of The Xenopus Tfiiia Gene In Somatic Cells, Ernest Martinez, Giorgio Lagna, Robert G. Roeder

Biology

Xenopus TFIIIA gene expression is developmentally regulated. The per cell level of steady-state TFIIIA mRNA present in oocytes is drastically reduced (10(6)-fold) in adult somatic cells, suggesting regulation at the transcriptional level. This is supported by the presence of TFIIIA mRNAs with different 5'-ends in oocytes and in somatic cells, which suggests the presence of distinct cell-/stage-specific promoters, i.e. a strong oocyte-specific and a weak somatic-specific promoter. Here, by mapping the 5'-ends of TFIIIA RNAs found in Xenopus somatic cells, we document the activity not only of an upstream somatic-specific promoter, but also of a down-stream “oocyte-specific” promoter that gives …

Letter To The Editor By M.C. Deruiter And A.C. Gittenberger-De Groot Relating To: "Technical Improvements In Corrosion Casting Of Small Specimens: A Study On Mesonephric Tubules And Vessels Of Chicken Embryos." [By A. Carretero, H. Ditrich, M. Navarro, H. Splechtna, J. Ruberte, Scanning Microscopy Vol. 7(4), P. 1333-1338 (1993)]., M. C. Deruiter, A. C. Gittenberger-De Groot

Scanning Microscopy

Dear Editor,

The topic of scanning electron microscopy (SEM) investigation of casting of vessels in the embryo still holds our interest. We are particularly focused on the possibilities of early injection as a method to support angiogenesis and vasculogenesis research in the embryo. It is questionable whether our technique leads to unreliable results because of severe trauma to the embryo as suggested by the above mentioned authors. The lower success yield might very well be the result of the higher friability of the embryo in general in this young stage.

Neuropeptide Degradation Produces Functional Inactivation In The Crustacean Nervous System, Melissa J. Coleman, P. H. Konstant, B. S. Rothman, Michael P. Nusbaum

WM Keck Science Faculty Papers

The pentapeptide proctolin (Proct.; Arg-Tyr-Leu-Pro-Thr) is a modulatory transmitter found throughout the crustacean nervous system. No information is available in this system, however, as to how the actions of this peptide are terminated. To study this issue in the crab Cancer borealis, we incubated exogenous proctolin (10(-5) M) with either the thoracic ganglion (TG) or with conditioned saline (CS) that had been preincubated with the TG. We removed aliquots at standard time points for analysis by reverse-phase high-performance liquid chromatography (HPLC). We found that over time the proctolin peak became progressively smaller, while three novel peaks appeared and increased in …

Rock Lobster Industry Advisory Commitee Chairman's Report, October 1994 - The Western Rock Lobster Fishery - Management Proposals For The 1994/95 And 1995/96 Seasons, Rock Lobster Industry Advisory Committee, Peter Rogers

Fisheries Management Papers

The failures of past restrictions on fishing effort to fully halt the decline of the breeding stock led to the formation of a sub-committee of the Rock Lobster Industry Advisory Committee. The prime objective of the sub-committee is to evaluate effective long term strategies for managing the fishery so that breeding stock is maintained at an adequate level despite the inevitable increases in catching efficiency. The purpose of this report is firstly to advise industry of the management proposals for the 1994/95 seasons and secondly to form a basis for industry consultation on management arrangements for the 1995/96 season.

Long Term Management Strategies For The Western Rock Lobster Fishery (4 Volumes) - Law Enforcement Considerations (Volume 4), Neil Mclaughlan

Fisheries Management Papers

This report has been prepared for the consideration of the RLIAC Sub Committee in consultation with members of the Sub Committee working group on law enforcement and with senior staff of the Operations Division of the Fisheries Department. It is focussed exclusively on law enforcement issues associated with the management options for the West Australian west coast rock lobster fishery which were under consideration by the Sub Committee at the time of report preparation and should be read in conjunction with Fisheries Management Paper No. 67 entitled "Evaluation of management options" which covers the broader industry management issues. This report …

Long Term Management Strategies For The Western Rock Lobster Fishery (4 Volumes) - A Market-Based Economic Assessment For The Western Rock Lobster Industry (May 1994) (Volume 3), Marec Pty Ltd

Fisheries Management Papers

In October 1992 a special Sub-Committee of the Rock Lobster Industry Advisory Committee was set up to consider and evaluate future management strategies for the rock lobster fishery. Pursuant to this the Director of Fisheries commissioned a marketing study that is the basis of this report. This study was commenced in early October 1993 and completed in May 1994. This study looked at the market implications of fishery's management strategies. In particular it assesses how the existing management structure limits the potential for the lobster industry to maximise the financial return, and in doing so provides an insight into the …

Long Term Management Strategies For The Western Rock Lobster Industry (4 Volumes) - Economic Efficiency Of Alternative Input And Output Based Management Systems In The Western Rock Lobster Fishery (Volume 2), Bob Lindner

Fisheries Management Papers

Since 1965, the Western Rock Lobster Fishery has been managed by what is essentially a license limitation scheme invoiving restricted entry for boats, and strict controls on the aggregate number of pots which can be used by the commercial fishing sector. By most measures, management of this fishery has been highly successful. Biological over-exploitation of the fish stock has been prevented, at least until recently. Notwithstanding these achievements, there is widespread concern that the future profitability, and even the viability of the industry is under threat unless the current management practices are reformed. Because of the complexity and intrinsic uncertainty …

Long Term Management Strategies For The Western Rock Lobster (4 Volumes) - Evaluation Of Management Options (Volume 1), B. K. Bowen, Rock Lobster Industry Advisory Committee

Fisheries Management Papers

This report has been written following approval by the Minister for Fisheries of a recommendation by the Rock LObster Industry Advisory Committee that a major evaluation of future management options for the western rock lobster fishery be undertaken. The report provides background information on the management strategies and principles of the fishery, its stock status, the use of input and output controls and the size of the fishing fleet. The report concludes with an examination of the effect of maintaining effort (input) controls and moving to a system of variable effort (TAE/ITEs) or moving to direct (output) controls on the …

Genetic Transformation Of The Lyme Disease Agent Borrelia Burgdorferi With Coumarin-Resistant Gyrb., D. Scott Samuels, Kathleen E. Mach, Claude F. Garon

Biological Sciences Faculty Publications

No useful method to genetically manipulate Borrelia burgdorferi, the causative agent of Lyme disease, has been developed previously. We have used resistance to the coumarin antibiotic coumermycin A1, an inhibitor of DNA gyrase, as a genetic marker to monitor the transformation of B. burgdorferi by electroporation. Introduction of site-directed mutations into the gyrB gene demonstrated that transformation was successful, provided evidence that homologous recombination occurs on the chromosome, and established that mutations at Arg-133 of DNA gyrase B confer coumermycin A1 resistance in B. burgdorferi. The coumermycin A1-resistant gyrB marker and genetic transformation can now be applied toward dissecting the …

Mechanism Of Gtp Hydrolysis By G-Protein Α Subunits, Christiane Kleuss, André S. Raw, Ethan Lee, Stephen R. Sprang, Alfred G. Gilman

Biological Sciences Faculty Publications

Hydrolysis of GTP by a variety of guanine nucleotide-binding proteins is a crucial step for regulation of these biological switches. Mutations that impair the GTPase activity of certain heterotrimeric signal-transducing G proteins or of p21(ras) cause tumors in man. A conserved glutamic residue in the α subunit of G proteins has been hypothesized to serve as a general base, thereby activating a water molecule for nucleophilic attack on GTP. The results of mutagenesis of this residue (Glu-207) in G(iα1) refute this hypothesis. Based on the structure of the complex of G(iα1) with GDP, Mg²⁺, and AlF₄/ …

Instructions For Building Two Live Traps For Small Mammals, Robert K. Rose

Biological Sciences Faculty Publications

The two live traps described herein, tested in the field over a period of 10 years, are sturdy, long-lasting, and relatively inexpensive to build with readily available materials and simple tools.

Force-Velocity And Power Characteristics Of Rat Soleus Muscle Fibers After Hindlimb Suspension, Kerry S. Mcdonald, C. A. Blaser, Robert H. Fitts

Biological Sciences Faculty Research and Publications

The effects of 1, 2, and 3 wk of hindlimb suspension (HS) on force-velocity and power characteristics of single rat soleus fibers were determined. After 1, 2, or 3 wk of HS, small fiber bundles were isolated, placed in skinning solution, and stored at -20 degrees C until studied. Single fibers were isolated and placed between a motor arm and force transducer, functional properties were studied, and fiber protein content was subsequently analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Additional fibers were isolated from soleus of control and after 1 and 3 wk of HS, and fiber type distribution …

Lag-2 May Encode A Signaling Ligand For The Glp-1 And Lin-12 Receptors Of C-Elegans, Samuel T. Henderson, Dali Gao, Eric J. Lambie, Judith Kimble

Dartmouth Scholarship

The C. elegans lag-2 gene is required for several cell-cell interactions that rely on the receptors GLP-1 and LIN-12. In this paper, we report that lag-2 encodes a putative membrane protein with sequence similarity to Drosophila Delta, a proposed ligand for the Notch receptor. Furthermore, we show that the lag-2 promoter drives expression of a reporter protein in the signaling distal tip cell (DTC) of the DTC/germline interaction. By in situ hybridization, we have found that endogenous lag-2 mRNA is present in the DTC but not the germ line. One fusion protein, called LAG-2::beta-gal(intra), rescues a lag-2 null mutant and …

The Pha-4 Gene Is Required To Generate The Pharyngeal Primordium Of Caenorhabditis-Elegans, Susan E. Mango, Eric J. Lambie, Judith Kimble

Dartmouth Scholarship

In the 4-cell Caenorhabditis elegans embryo, two blastomeres are destined to generate pharyngeal cells, each by a distinct developmental strategy: one pathway is inductive, while the other is autonomous. Here, we identify the pha-4 locus. In animals lacking pha-4 activity, an early step in pharyngeal organogenesis is blocked: no pharyngeal primordium is formed and differentiated pharyngeal cells are absent. Most other tissues are generated normally in pha-4 mutants, including cells related to pharyngeal cells by cell lineage and position. Thus, pha-4 activity is required to form the pharyngeal primordium. We propose that pha-4 marks a convergence of the inductive and …

Urinary Citrate, Bone Resorption And Intestinal Alkali Absorption In Stone Formers With Fasting Hypercalciuria, Piergiorgio Messa, Giuseppe Mioni, L. Paganin, A. Cruciatti, P. Lo Greco, D. Turrin

Scanning Microscopy

Reduced citrate in urine and increased fasting excretion of calcium are abnormalities frequently reported in stone forming (SF) patients. Increased dietary acid (or reduced alkali) introduction or absorption may be a potential cause of both these pathological findings. To test this hypothesis, we studied 64 SF patients {32 with fasting hypercalciuria (FH) and 32 without FH (NFH)}. After a basal evaluation for nephrolithiasis, while on a 500 mg calcium diet, they were evaluated for: (1) daily intestinal alkali absorption (IAA), by urinary electrolyte excretion; (2) basal concentrations of PTH, calcitonin (CT) and 1,25(OH)2-VitD; (3) oral calcium load for evaluation of …

Chemical Composition Of Gaas Oxide Layers By Auger In-Depth Profiles And X-Ray Photoelectron Spectroscopy Experiments, J. F. Bresse, C. Cardinaud

Scanning Microscopy

GaAs oxide layers resulting from an oxygen plasma etching have been studied by Auger in-depth profiles and angle-resolved XPS experiments. From the Auger profiles, using the sequential layer sputtering (SLS) treatment, a quantitative determination of thickness and composition of the oxide layers has been performed. A model with several layers has been deduced. From the angle-resolved X-ray photoelectron spectroscopy (XPS) experiments, another model with several layers of different chemical compounds has also been deduced. The oxide layer is non-uniform in thickness and composition. Two or three different oxide layers are formed depending on the probed area. The interface layer is …

Characterization Of Metal Aggregates By Scanning Microscopy: Particle Sizes And Space Distribution In Intermetallic Particles, M. O. Delcourt, F. Yala, E. Merlen, S. Remita, N. Keghouche, E. Delarue

Scanning Microscopy

Various metal aggregates prepared using ionizing radiation were studied by microscopy techniques. A metal deposit onto a carbon felt obtained from solutions containing Pt and Ru was shown to consist of nanometric particles containing both metals. Another study deals with a subnanometric silver aggregate. The nuclearity of the aggregate was studied by scanning tunneling microscopy (STM). Additional information from pulse radiolysis experiments allowed the determination of the Ag₇³⁺ stoichiometry.

The third material consisted of Ag/Pd submicron powders (70/30 or 75/25% w/w) used in electronics, and made of spherical bimetallic grains; X-ray diffraction showed segregation. The spatial distribution of …

Molecular Imaging Of Petroleum Asphaltenes By Scanning Tunneling Microscopy: Verification Of Structure From 13c And Proton Nuclear Magnetic Resonance Data, G. W. Zajac, N. K. Sethi, J. T. Joseph

Scanning Microscopy

Scanning tunneling microscopy (STM) was used to verify the molecular structure of Maya asphaltene which had been derived from combined ¹³C and proton nuclear magnetic resonance (NMR) experiments. Petroleum asphaltenes are known to contain large polynuclear aromatic centers with aliphatic sidechains. Average molecular models of Maya asphaltenes were derived using studies which included combined proton and ¹³C NMR data to determine total aromatic carbon content and the ratio of peripheral to internal aromatic ring carbons. These parameters permitted estimating the average number of aromatic rings per condensed cluster.

These Maya asphaltenes were imaged by scanning tunneling microscopy (STM) …

A New Atomic Force Microscopy Technique For The Measurement Of The Elastic Properties Of Biological Materials, W. Xu, P. J. Mulhern, B. L. Blackford, M. H. Jericho, I. Templeton

Scanning Microscopy

We developed a new technique to measure elastic properties by using the atomic force microscope (AFM) tip to press samples into grooves etched in a GaAs substrate.

We measured the Young's modulus of β-chitin fibres with cross-sections less than 40 nm X 20 nm to be 1-2 X 10¹¹ N/m². In the isotropic approximation, the Young's modulus of the S-layer sheath of the archaeobacterium Methanospirillum hungatei was 1-3 X 10¹⁰ N/m². By testing the sheath to breaking strength we estimated the bacterium can sustain an internal pressure as high as 100-200 atmospheres (1-2 x …

Nanowriting On An Atomically Flat Gold Surface With Scanning Tunneling Microscope, C. Lebreton, Z. Z. Wang

Scanning Microscopy

We present new experimental results of writing stable features on atomically flat surfaces of gold films. By applying successive voltage pulses across the tunneling gap in controlled atmosphere, nearly 150 individual holes are produced to record one message. The writing process has a higher success rate in nitrogen gas with the presence of water or ethanol vapour. Written letters remain stable for more than 4 days in dry nitrogen gas, in contrast to some previous STM results of monatomic step movement on the gold surface. By changing the vapour pressure, pulse amplitude and polarity, we succeed in controlling the gold …

Electron Spectroscopy And Atomic Force Microscopy Studies Of Dna Adsorption On Mica, Carol E. Rabke, Lisa A. Wenzler, Thomas P. Beebe Jr.

Scanning Microscopy

Various methods for the deposition of deoxyribonucleic acid (DNA) molecules on mica are investigated to determine their reproducibility, and to quantify their ability to bind DNA. The use of these deposition methods for sample preparation for biological scanning tunneling microscopy (STM) and atomic force microscopy (AFM) studies is discussed. Auger electron spectroscopy (AES) and electron spectroscopy for chemical analysis (ESCA) were used to investigate the quantity of DNA adsorbed. AFM images of DNA deposited using the methods investigated are presented. The combination of AFM results with AES and ESCA results provides a basic understanding of the deposition techniques studied and …

Adsorption Of Fibrinogen On Thin Oriented Poly(Tetrafluoroethylene) (Ptfe) Fibres Studied By Scanning Force Microscopy, J. R. Rasmusson, R. Erlandsson, W. R. Salaneck, M. Schott, D. T. Clark, I. Lundström

Scanning Microscopy

We have investigated fibrinogen adsorption on ordered poly(tetrafluoroethylene), PTFE, fibres deposited on hydrophilic and hydrophobic silicon substrates. Fibrinogen molecules appear to adsorb with their long axis perpendicular to the fibre direction for PTFE fibres having widths of less than 100 nm. On these thin fibres, fibrinogen apparently forms close packed bands or clusters, consisting of small integer numbers of molecules arranged parallel to each other. On broader (> 100 nm) PTFE fibres, the fibrinogen forms two dimensional networks. The orientation of the molecules in these networks is random in the central flat part of the fibres but perpendicular to the …

High Resolution Electron Beam Induced Current Measurements In An Scanning Tunneling Microscope On Gaas-Mesfet, P. Koschinski, V. Dworak, L. J. Balk

Scanning Microscopy

Recently, the first results of electron beam induced current (EBIC) measurements in a scanning tunneling microscope (STM) have been reported. Although the acquired results match with those obtained in conventional EBIC investigations, the interpretation of the obtained results is still restricted solely to a qualitative discussion. In this paper, a quantitative approach is used for two-dimensional numerical simulations of induced currents in GaAs-MESFET leading to a first starting point for a sophisticated interpretation of the dependence of induced currents on experimental and device parameters.

Diluted And Undiluted Mercox Severely Destroy Unfixed Endothelial Cells. A Light And Electron Microscopic Study Using Cultured Endothelial Cells And Tadpole Tail Fin Vessels, J. Gassner, A. Lametschwandtner, T. Weiger, H. C. Bauer

Scanning Microscopy

Mercox is a methylmethacrylate-based resin which is widely used for vascular corrosion casting with subsequent scanning electron microscopic analysis. In the present study the effect of undiluted and diluted Mercox (4+1; volume + volume; Mercox: monomeric methylmethacrylate (MMA); 0.02 g catalyst MA/ml Mercox) and methylmethacrylate with and without catalyst MA (0.625 g/10 ml MMA) on fixed and unfixed endothelial cells was studied. Light microscopy (LM) of cultured capillary endothelial cells (ECs), which were replicated with diluted or undiluted Mercox shows degranulation and membrane perturbation of ECs, while no morphological changes occur in glutaraldehyde-prefixed ECs. Scanning electron microscopy (SEM) of replicas …

Superstructures Of Graphite Intercalation Compound Formed By Sodium-Hydroxide Solution Studied By Scanning Tunneling Microscopy, Koji Miyake, Aiso Yoshiaki, Makoto Komiyama, Hidemi Shigekawa

Scanning Microscopy

Highly oriented pyrolytic graphite (HOPG) treated with sodium hydroxide solution was found to show an X-ray diffraction pattern characteristic of a stage-8 intercalation compound. Superstructures such as 2 X 2, √3 X √3 and noble orthorhombic lattices were observed on the NaOH-treated graphite surfaces by scanning tunneling microscopy, as was previously observed on stage-1 alkali-metal graphite intercalation compound (GIC) surfaces formed by Li, K, Rb and Cs intercalates. The orthorhombic phase has a periodic structure formed by four bright and two dark rows, which were explained by the intercalant arrangement occupying two different sites, in the GIC.

Data Handling In Quantitative Microanalysis In Biology, V. Starý

Scanning Microscopy

In cell biology, electron probe X-ray microanalysis can reveal the distribution of chemical elements inside a single cell. The full description of a biological system (cell population, tissue) requires a great number of spot measurements. In quantitative analysis, the measurements are subject to experimental errors of several types; moreover, the relations between the resulting values are usually more interesting than the absolute concentrations. Nevertheless, the proper evaluation of quantitative values can discover information more on the object of study.

A system of simple statistical tests is suggested here which can solve several problems. Some concentration values can be far from …

Role Of Agglomeration In The Early Stages Of Papillar Stone Formation, O. Söhnel, F. Grases, L. Garcia-Ferragut

Scanning Microscopy

Possible effects of crystal agglomeration on the early stages of calcium oxalate papillar stone formation are evaluated. The collecting ducts are filled with liquid that flows laminarly as established through hydrodynamical and physicochemical considerations. Under such conditions, agglomeration due to laminar shear forces proceeds. Agglomeration of calcium oxalate monohydrate crystals present in urine at a concentration typical for clinically observed crystalluria cannot result in the formation of a particle sufficiently large enough to be retained in the Bellini's duct and become a papillar stone nidus (nucleus). Formation of such an aggregate during the passage time of urine through the duct …

Review Of Survival, Reproduction, And Behavior By J.R. Krebs And N.B. Davies, Marlene Zuk, Torgeir S. Johnsen, Gita R. Kolluru, Kurt A. Mckean, Bradd Schulke

Biological Sciences

No abstract provided.

Future Of Management Of Recreational Gill, Haul, And Cast Netting In Western Australia And Summary Of Submissions To The Netting Review, F. B. Prokop, L. M. Adams

Fisheries Management Papers

The results of a major review into recreational gill and haul netting in Western Australia were announced by the Minister for Fisheries, Hon. Monty House MLA on 24 December 1993. This document presents the findings of the recreational netting review and the process which resulted in the announced changed to management practices.

Direct Observation By Scanning Tunneling Microscopy Of The Two-Dimensional Lattice Structure Of The S-Layer Sheath Of The Archaeobacterium Methanospirillum Hungatei Gp1, B. L. Blackford, W. Xu, M. H. Jericho, P. J. Mulhern, M. Firtel, T. J. Beveridge

Scanning Microscopy

Observation of the two-dimensional (2-D) 3 nm x 3 nm lattice structure of the S-layer sheath of the archaeobacterium Methanospirillum hungatei is reported for the first time by scanning tunneling microscopy. The samples consisted of sheath fragments deposited on a TaSe₂ substrate and coated with a Pt/Ir film. In addition to confirming the 2-D structure, the images reveal some new information about the nano-scale details of the sheath structure. A lateral resolution of 1 nm was achieved, suggesting that the grain size of the Pt/Ir films was much less than for similar films deposited on a smooth metal surface.