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Genetic Variation In Latent Period Among Isolates Of Puccinia Recondita F. Sp. Tritici On Partially Resistant Wheat Cultivars, Jeffrey Lehman

Biology and Earth Science Faculty Scholarship

The durability of partially resistant wheat cultivars to wheat leaf rust depends on the amount of genetic variation in parasitic fitness within populations of the pathogen Pucciniareconditaf. sp.tritici. To assess the durability ofpanialresistance, phenotypic variation inlatentperiod (a major component of parasitic fitness) was quantified and partitioned into genetic and nongenetic components for isolates of P.reconditaf. sp.triticion susceptible and partially resistant cultivars. Latent periods among isolates differed by 24 to 27% on individual partially resistant cultivars. In simulated epidemics, isolates with short latent periods caused 2 to 2.5 times more disease and overcame 13 to 35% of the

resistance of four …

A Yohimbine-Dependent, Uk14,304 Induced Ion Transient In Ht29 Cells Studied By X-Ray Microanalysis, Wei Zhang, Godfried M. Roomans

Scanning Microscopy

The response of HT29 cells to α₂-adrenoceptor agonists was investigated by X-ray microanalysis. Treatment of the cells with 10 μM UK14,304, an α₂-agonist, resulted in a rise of intracellular Cl and Na, suggesting an antisecretory effect. When the cells were exposed to yohimbine or RX821002, both of which are arantagonists, the former had no effect, whereas the latter produced a minor decrease of the cellular Na, Cl and K concentrations. However, when the cells were pretreated with yohimbine, UK14,304 induced a transient change in ion concentrations, which consisted of a rapid increase of intracellular Cl, Na …

Cytoskeleton Architecture Of C6 Rat Glioma Cell Subclones Whole Mount Electron Microscopy And Immunogold Labeling, Wolfgang Bohn, Dörte Etzrodt, Roland Foisner, Gerhard Wiche, Peter Traub

Scanning Microscopy

Whole mount electron microscopy of extracted cells combined with immunogold labeling techniques can be used to characterize the cytoskeletal architecture of cultured cells. As shown with subclones of the C6 rat glioma cell line, heavy metal shadowing was suitable for getting basic information concerning the arrangement of the various filament types within the networks. Pure carbon shadowing combined with immunogold double labeling proved to be optimal to identify linkages between filaments, to localize filament associated proteins and to follow the arrangement of filaments in dense arrays such as lamellipodiae and cell margins. Thin connecting filaments which interact with actin as …

Imaging Soft Materials With Scanning Tunneling Microscopy, J. T. Woodward Iv, J. A. Zasadzinski

Scanning Microscopy

By modifying freeze-fracture replication, a standard electron microscopy fixation technique, for use with the scanning tunneling microscope (STM), a variety of soft, non-conductive biomaterials can be imaged at high resolution in three dimensions. Metal replicas make near ideal samples for STM in comparison to the original biological materials. Modifications include a 0.1 μm backing layer of silver and mounting the replicas on a fine-mesh silver filters to enhance the rigidity of the metal replica. This is required unless STM imaging is carried out in vacuum; otherwise, a liquid film of contamination physically connects the STM tip with the sample. This …

Experimental Measurements Of Electron Stopping Power At Low Energies, David C. Joy, Suichu Luo, Raynald Gauvin, Pierre Hovington, Neal Evans

Scanning Microscopy

The electron stopping power has been measured for twelve elements and fifteen compounds, over the energy range from 1 eV to 10 keV, by the analysis of electron energy loss spectra, optical data, and photon mass absorption data. Values of the effective mean ionization potential Jeff and the effective number of participating electrons Neff have also been determined in each case. The results obtained have been compared with other experimental data, with first-principles theoretical calculations, and with a number of proposed analytical models.

Energy Dispersive X-Ray Microanalysis Of The Dentin In Rat Molars After Corticosteroid Treatment, Karin Nasstrom, Rolf Odselius, Arne Petersson

Scanning Microscopy

The aim of this study was to investigate whether the calcium (Ca) and phosphorus (P) composition of corticosteroid induced dentin was the same as in normally developed dentin. Seven rats were given corticosteroids intravenously and three rats served as controls. Energy dispersive X-ray microanalysis (EDX) was carried out on the axially sawn roots of the molars. Measurements were made at 20 sites, equally distributed in the buccal, mesial, lingual and distal direction. The results showed that the Ca/P ratio (weight %) was slightly above 2.0 in both the experimental and the control group, indicating that the corticosteroid induced dentin had …

Patterns Of Calcium Oxalate Crystal Production By Three Species Of Wood Decay Fungi, Jon H. Connolly, Howard J. Arnott, Jody Jellison

Scanning Microscopy

Wood decay experiments using red spruce wood resting on moist soil were conducted to discern temporal and spatial patterns of calcium oxalate (CaOx) crystal production by three species of fungi over the course of decay. All three species produced crystals of calcium oxalate dihydrate, but not monohydrate, in and on wood. Over the course of decay, the production of CaOx crystals was shown to be heterogeneous in both space and time. The relative quantity, morphology and longevity of CaOx crystals varied among species. Gloeophyllum (G.) trabeum produced substantial quantities of "free" crystals; Fomitopsis (F.) pinicola produced encrusting crystals; and Trichaptum …

Atomic Force Microscopy Of Dna Electrophoresed Onto Silylated Mica, Irène Revenko, Helen G. Hansma

Scanning Microscopy

A new technique has been developed for electrophoresing DNA molecules from an agarose gel onto a silylated mica substrate where they can be imaged with an atomic force microscope (AFM). With a simple modification, the technique can also be used for polyacrylamide gels. This method does not require purification of samples from the gels. Using tapping mode AFM, we have observed plasmids after electrophoretic separation into two bands. Differences in conformation were observed between the plasmids in the two bands.

Regenerating Synovial Lining Of The Normal Rabbit Knee: A Scanning Electron Microscopy Study, Haim Stein, Daniel Levanon

Scanning Microscopy

Regeneration of the synovial lining in the synovectomized rabbit knee was studied using the scanning electron microscope. The resected synovia regenerated considerably 3 weeks after synovectomy. However, 44 weeks following excision, their surface morphology was still very different from that of the normal tissue of intact animals. The regenerated synovia were characterized by three main features: the large number of various patterns, the many fields harboring fibrillation and the almost total lack of a bubble layer (the latter was formerly shown to be predominant on normal, intact synovia). The surface morphology of the non-operated (contralateral) knee differed greatly from that …

Cultural Values Lower Redwood Creek, Susie Van Kirk

Susie Van Kirk Papers

Levee construction on lower Redwood Creek from near its mouth to the mouth of Prairie Creek was completed by the Corps of Engineers in 1968, resulting in significant impairment of the estuary's hydrology and its biological functions. In an effort to reestablish those functions and more particularly the fisheries of the creek, Redwood National and State Parks is developing a plan for estuary management. The following general statement about cultural values in the project area and vicinity was prepared to expand the historical information in the draft plan.

A Report On The Issues Affecting The Use Of The Dampier Archipelago, Peter Driscoll

Fisheries Management Papers

This report was commissioned by the Minister for Fisheries following concerns about resource sharing, allocation of licences and leases for pearling and aquaculture, recreational and commercial fishing opportunities, and local residents continued ability to access the islands and marine areas of the Dampier Archipelago. The purpose of this report is to provide a scoping document for a marine planning study for the Dampier Archipelago for the Fisheries Department and the Minister for Fisheries.

Fishermen's Views On The Future Management Of The Rock Lobster Fishery: A Report Prepared On Behalf Of The Rock Lobster Industry Advisory Committee, The Marketing Centre, Rock Lobster Industry Advisory Committee

Fisheries Management Papers

In June 1995, a self-completion survey of fishermen in the rock lobster fishery was sent out by The Marketing Centre to 589 licensees. A total of 206 valid responses were received. The questionnaire was fairly long and dealt with a number of complex issues. As such, this response rate of 36.0% compares favorably with the average for postal surveys of around 40.0%. The following represents the main findings from the survey.

Same Fish - Different Rules - Proceedings Of The National Fisheries Management Network Workshop Held As Part Of The Third Australasian Fisheries Managers Conference August 1995, F. B. Prokop

Fisheries Management Papers

This workshop represents the third time that a specific recreational fisheries workshop has been held in conjunction with the Australasian Fisheries Managers Conference. It is designed to analyse the different management approaches from the various fisheries agencies which have responsibility for selected species. The case studies that make up the workshop have been selected to represent the diversity of situations including freshwater, marine, pelagic and invertebrate species.

Soleus Fiber Force And Maximal Shortening Velocity After Non-Weight Bearing With Intermittent Activity, Jeffrey J. Widrick, J. J. Bangart, M. Karhanek, Robert H. Fitts

Biological Sciences Faculty Research and Publications

This study examined the effectiveness of intermittent weight bearing (IWB) as a countermeasure to non-weight-bearing (NWB)-induced alterations in soleus type I fiber force (in mN), tension (P_o; force per fiber cross-sectional area in kN/m^-2), and maximal unloaded shortening velocity (V_o, in fiber lengths/s). Adult rats were assigned to one of the following groups: normal weight bearing (WB), 14 days of hindlimb NWB (NWB group), and 14 days of hindlimb NWB with IWB treatments (IWB group). The IWB treatment consisted of four 10-min periods of standing WB each day. Single, chemically permeabilized soleus fiber segments …

Effect Of Intracellular And Extracellular Ion Changes On E–C Coupling And Skeletal Muscle Fatigue, Robert H. Fitts, Edward Michael Balog

Biological Sciences Faculty Research and Publications

The causative factors in muscle fatigue are multiple, and vary depending on the intensity and duration of the exercise, the fibre type composition of the muscle, and the individual's degree of fitness. Regardless of the aetiology, fatigue is characterized by the inability to maintain the required power output, and the decline in power can be attributed to a reduced force and velocity. Following high-intensity exercise, peak force has been shown to recover biphasically with an initial rapid (2 min) recovery followed by a slower (50 min) return to the pre-fatigued condition. The resting membrane potential depolarizes by 10–15 mV, while …

Determinants Of Weddellite Formation: Chondroitin Sulfates And Citrate Determine Weddellite Formation In Vitro, Kookmin M. Kim

Scanning Microscopy

In synthetic urine (SU), addition of oxalate tends to form monohydrates of calcium oxalate. However, addition of oxalate to natural urine preferably forms calcium oxalate dihydrate (COD). Urine apparently contains a determinant for COD formation. To identify the determinant, the effects of pH, temperature, oxalate, calcium, urate, citrate, magnesium, sulfate and chondroitin sulfates (CS) on calcium oxalate crystal formation were studied. Lower temperatures, higher oxalate concentrations and higher pH favored COD formation in a SU. Mixed CS in the presence of citrate were the most decisive determinant of COD formation. Substitution of CS for agar and gelatin produced similar results, …

Potential Sputtering Of Protons With Slow Multiply Charged Ions, Yasunori Yamazaki, Nobukazu Kakutani

Scanning Microscopy

Experimental findings of insulator sputtering with slow multiply charged ions are reviewed with particular emphasis on proton sputtering, including recent studies which pay attention not only to the yields, but also to the energy distributions of sputtered particles. A simplified scenario of multiply charged ion interaction with a solid surface is discussed, which consists of two stages, i.e., resonant charge transfers well above the surface (the stage I), and a violent collision with the surface transferring a major part of the potential energy (the stage II). A couple of processes relating to the sputtering in the stages I and II …

Effects Of Ionizing Radiation On Cartilage: Emphasis On Effects On The Extracellular Matrix, M. Cornelissen, H. Thierens, L. De Ridder

Scanning Microscopy

In this report, we review data dealing with radiation effects on cartilage. More specifically, we emphasize on alterations caused in the extra-cellular cartilage matrix. Although radiation studies predominantly describe the effect on the structure of DNA and on the mitotic activity of cells, alterations caused by the effect on the non-mitotic activity can also be important. Cartilage, having an extracellular matrix composed of 2 major components, aggrecan and collagen, provides a good model to study this kind of radiation effects. The following topics concerning literature data are summarized: effects on the amount of matrix synthesized, effects on the activity of …

Interactions Involving The Human Rna Polymerase Ii Transcription/Nucleotide Excision Repair Complex Tfiih, The Nucleotide Excision Repair Protein Xpg, And Cockayne Syndrome Group B (Csb) Protein, Narayan Iyer, Michael S. Reagan, Kou-Juey Wu, Bertram Canagarajah, Errol C. Friedberg

Biology Faculty Publications

The human basal transcription factor TFIIH plays a central role in two distinct processes. TFIIH is an obligatory component of the RNA polymerase II (RNAP II) transcription initiation complex. Additionally, it is believed to be the core structure around which some if not all the components of the nucleotide excision repair (NER) machinery assemble to constitute a nucleotide excision repairosome. At least two of the subunits of TFIIH (XPB and XPD proteins) are implicated in the disease xeroderma pigmentosum (XP). We have exploited the availability of the cloned XPB, XPD, p62, p44, and p34 genes (all …

Ionizing Radiation-Induced Apoptosis And Dna Repair In Murine Erythroleukemia Cells, R. Di Pietro, L. Centurione, E. Santavenere, M. A. Centurione, G. Sanitá Di Toppi, L. Zamai, R. Rana

Scanning Microscopy

A morphological study of DNA repair and apoptotic patterns in relationship with cell cycle events was performed on murine erythroleukemia cells. The presence and distribution of DNA replicon sites were evaluated through the BrdU-anti BrdU immunofluorescence and immunogold techniques in light and electron microscopy. Different patterns of labelling and percentages of BrdU positive cells were observed depending on irradiation dose (up to 60 Gy) and time in post-irradiation culture (up to 24 hours). An enlargement of the S phase of the cell cycle was evidenced 18 hours post-irradiation as determined by flow cytometry analysis. The high resolution approach showed that, …

The Nucleation And Growth Of Calcium Phosphate Crystals At Protein And Phosphatidylserine Liposome Surfaces, G. H. Nancollas, A. Tsortos, A. Zieba

Scanning Microscopy

The kinetics of calcium phosphate crystal growth at the surfaces of proteins and phospholipids has been investigated using free drift and constant composition methods in supersaturated calcium phosphate solutions (relative supersaturations: with respect to hydroxyapatite, HAP, σHAP = 15.0, and with respect to octacalcium phosphate, OCP, σOCP = 1. 9). Fibrinogen and collagen molecules adsorbed at hydrophobic surfaces as well as uncross-linked collagen fibrils induce ion binding and subsequent nucleation of calcium phosphate. The formation of OCP on phosphatidylserine vesicles introduced to highly supersaturated calcium phosphate solutions probably involves the interaction of the calcium ions with the ionized carboxylic groups …

Hydration-Scanning Tunneling Microscopy As A Reliable Method For Imaging Biological Specimens And Hydrophilic Insulators, M. Heim, R. Eschrich, A. Hillebrand, H. F. Knapp, G. Cevc, R. Guckenberger

Scanning Microscopy

The recently discovered high lateral conductivity of molecularly thin adsorbed water films enables investigation of biological specimens, and even of surfaces of hydrophilic insulators by scanning tunneling microscopy (STM). Here we demonstrate the capabilities of this method, which we call hydration-STM (HSTM), with images of various specimens taken in humid atmosphere: We obtained images of a glass coverslip, collagen molecules, tobacco mosaic virus, lipid bilayers and cryosectioned bovine achilles tendon on mica. To elucidate the physical mechanism of this conduction phenomenon we recorded current-voltage curves on hydrated mica. This revealed a basically ohmic behavior of the J-V curves without a …

Formation Of Hydrated Calcium Oxalates In The Presence Of Poly-L-Aspartic Acid, Jeffrey A. Wesson, Elaine Worcester

Scanning Microscopy

The effect of poly-L-aspartic acid (PA) on the crystal structure of calcium oxalate crystals grown after spontaneous nucleation was evaluated as a function of relative supersaturation and calcium:oxalate ratio in a buffered salt solution, with pH and ionic strength in the range of normal human urine. PA was used as a model for naturally occurring acidic urine proteins that have been shown to inhibit nucleation and growth of calcium oxalate crystals. The crystals grown were characterized by optical microscopy and X-ray powder diffraction. It was observed that calcium oxalate monohydrate was the preferred crystalline form in the absence of added …

Early Post-Radiation Changes Of Red Blood Cell Shape In Rats, V. D. Zharskaya, A. B. Chukhlovin

Scanning Microscopy

Scanning electron microscopy (SEM) of red blood cells in whole blood samples from rats was performed following acute γ-irradiation of animals with 0.25 to 1 Gy. Increased incidence of echinocytosis was observed and found to be dose- and time-dependent. At a higher radiation dose (1 Gy), echinocytosis was revealed within 5 minutes after treatment and persisted up to 3 weeks. The data demonstrate the applicability of SEM for detecting minimal radiation-induced lesions of red blood cells.

Role Of Calcium Oxalate Monohydrate Crystal Interactions With Renal Epithelial Cells In The Pathogenesis Of Nephrolithiasis: A Review, John C. Lieske, Mary S. Hammes, F. Gary Toback

Scanning Microscopy

Renal tubular fluid in the distal nephron is supersaturated with calcium and oxalate ions that nucleate to form crystals of calcium oxalate monohydrate (COM), the most common crystal in renal stones. How these nascent crystals are retained in the nephron to form calculi in certain individuals is not known. Recent studies from this laboratory have demonstrated that COM crystals can bind within seconds to the apical surface of renal epithelial cells, suggesting one mechanism whereby crystals could be retained in the tubule. Adherence of crystals to cells along the nephron may be opposed by specific urinary anions such as glycosaminoglycans, …

A Cell Cycle-Regulated Bacterial Dna Methyltransferase Is Essential For Viability, Craig Stephens, Ann Reisenaur, Rachel Wright, Lucy Shapiro

Biology

The CcrM adenine DNA methyltransferase, which specifically modifies GANTC sequences, is necessary for viability in Caulobacter crescentus. To our knowledge, this is the first example of an essential prokaryotic DNA methyltransferase that is not part of a DNA restriction/modification system. Homologs of CcrM are widespread in the Cl subdivision of the Proteobacteria, suggesting that methylation at GANTC sites may have important functions in other members of this diverse group as well. Temporal control of DNA methylation state has an important role in Caulobacter development, and we show that this organism utilizes an unusual mechanism for control of remethylation of newly …

Crystallization And Stone Formation Inside The Nephron, Dirk J. Kok

Scanning Microscopy

A model is presented visualizing the events leading to calcium-salt, crystal- and stone-formation inside the nephron. For each nephron segment, handling of urine components relevant to stone formation is considered and urine composition determined. This information was applied to nucleation experiments simulating passage of urine through a nephron. The model and in vitro experiments suggest that within normal transit times for the respective nephron segments, particles of a hydroxyapatite-like material first form near the bend in the Loop of Henle of juxtamedullary nephrons. From there on, calcium oxalate particles start to appear: first dihydrate, then monohydrate. In the collecting duct …

Use Of Rostral Characters For Identifying Adult Billfishes (Teleostei: Perciformes: Istiophoridae And Xiphiidae), Harry L. Fierstine, Nicole L. Voigt

Biological Sciences

Seven species of the family Istiophoridae and Xiphias gladiu6 were identified using only features of their rostrum. In the Istiophoridae, two rostral regions were emphasized, one-fourth and one·half the distance between the distal tip and the orbital margin of the lateral ethmoid bone. Characters studied in each region were the depth and width of rostrum and height, width, and position of nutrient canals (as seen in cross-section). Characters studied without reference to region were the distribution of denticles on both dorsal and ventral surfaces of the bilI and position of the prenasal bone. In the Xiphiidae, the only characters studied …

Micromorphology Of The Fibers Behind The Frons Plate And Its Adjacent Regions In The Oriental Hornet (Hymenoptera, Vespinae), Jacob S. Ishay, Alina Landsberg, Smadar Pelah

Scanning Microscopy

The present study describes the fibers occurring in the space extending behind the frons plate, or the region between the ocelli and the clypeal plate of the Oriental hornet. These fibers connect to the brain in the anterior part of the head in a zone which is demarcated by an imaginary line traversing the upper part of the two omrnatidia. Static fibers are present in the upper part and in the center of the space. These static fibers do not move with acceleration of the structures attached to the head. They are perpendicular to the frons plate, are relatively numerous …

Trade-Offs In Parasitology, Evolution And Behavior, Marlene Zuk, M. J. Bryant, Gita R. Kolluru, V. Mirmovitch

Biological Sciences

No abstract provided.