Digital Commons Network^™

Characterization Of Diverse 2,4-Dichlorophenoxyacetic Acid-Degradative Plasmids Isolated From Soil By Complementation, Eva M. Top, William E. Holben, Larry J. Forney

Biological Sciences Faculty Publications

The diversity of 2,4-dichlorophenoxyacetic acid (2,4-D)-degradative plasmids in the microbial community of an agricultural soil was examined by complementation. This technique involved mixing a suitable Alcaligenes eutrophus (Rif^r) recipient strain with the indigenous microbial populations extracted from soil. After incubation of this mixture, Rif^r recipient strains which grow with 2,4-D as the only C source were selected. Two A. eutrophus strains were used as recipients: JMP228 (2,4-D^-), which was previously derived from A. eutrophus JMP134 by curing of the 2,4-D-degradative plasmid pJP4, and JMP228 carrying pBH501aE (a plasmid derived from pJP4 by deletion of a …

Maintaining Bird Diversity In Western Larch/Douglas-Fir Forests, Bret W. Tobalske, Raymond C. Shearer, Richard L. Hutto

Biological Sciences Faculty Publications

Bird occurrences were evaluated under four stand conditions in western larch/Douglas-fir forests: clearcut, partial cut, unlogged (fragmented), and contiguous forest. Frequencies were noted for foraging guilds, tree gleaners, flycatchers, nesting guilds, tree drillers, and primary cavity nesters. Managers should consider a diversity of habitat conditions if maintaining habitat for bird species is an objective.

Reproduction Of The Rare, Riparian Orchid Spiranthes Diluvialis: Pollination Ecology, Variations In Reproductive Success, And Implications For Conservation, Sedonia D. Sipes

Biology

I examined the reproductive biology and pollination of Ute lady's tresses, Spiranthes diluvialis Sheviak, a rare orchid from Colorado and Utah. S. diluvialis exhibits a mixed-mating system. Outcrossing is promoted by protandrous flowers and by acropetal movement of long-tongued bees (predominantly bumblebees) on inflorescences. However, male and female phases overlap, and flowers are fully self-compatible. No autogamous or agamospermous seed set was observed, indicating a pollinator is required for reproduction. Fruit set and pollinia removal varied greatly within and between flowering seasons. I found evidence for both resource and pollinator limitation of fruit set, and suggest that the limiting factor …

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.

A Taxonomic Revision Of Neotropical Discocarpus (Euphorbiaceae), Sheila Mae Hayden

Master's Theses

This thesis is a taxonomic revision of Discocarpus, a genus of three species of trees from seasonally inundated forests of northern South America. Discocarpus is classified in the family Euphorbiaceae. The Euphorbiaceae or spurge family is a large and diverse taxon of angiosperms consisting of approximately 7000 species placed in 300 genera, comprising 49 tribes and 5 subfamilies (Webster 1994b). The origin of the family is likely Western Gondwanaland, and the earliest fossils identified as Euphorbiaceae date to the Paleocene (Raven & Axelrod 1974). The family is predominately tropical, however, species of Euphorbiaceae are important throughout most of the world …

Position Effect Variegation In Drosophila Is Associated With An Altered Chromatin Structure, Lori L. Wallrath, Sarah C.R. Elgin

Biology Faculty Research

A euchromatic gene placed in the vicinity of heterochromatin by a chromosomal rearrangement generally exhibits position effect variegation (PEV), a clonally inherited pattern showing gene expression in some somatic cells but not in others. The mechanism responsible for this loss of gene expression is investigated here using fly lines carrying a P element containing the Drosophila melanogaster white and hsp26 genes. Following mobilization of the P element, a screen for variegation of white expression recovered inserts at pericentric, telomeric, and fourth chromosome regions. Previously identified suppressors of PEV suppressed white variegation of pericentric and fourth chromosome inserts but not telomeric …

Arachidonic Acid As A Possible Negative Feedback Inhibitor Of Nicotinic Acetylcholine Receptors On Neurons, Sukumar Vijayaraghavan, Bo Huang, Edward M. Blumenthal, Darwin K. Berg

Biological Sciences Faculty Research and Publications

Neuronal acetylcholine receptors, being highly permeable to calcium, are likely to regulate calcium-dependent events in neurons. Arachidonic acid is a membrane-permeant second messenger that can be released from membrane phospholipids by phospholipases in a calcium-dependent manner. We show here that activation of neuronal acetylcholine receptors triggers release of ³H-arachidonic acid in a calcium-dependent manner from neurons preloaded with the fatty acid. Moreover, low concentrations of arachidonic acid reversibly inhibit the receptors and act most efficiently on receptors likely to have the highest permeability to calcium, namely receptors containing α7 subunits. Low concentrations of arachidonic acid also reversibly inhibit α7- …

Lipopolysaccharide Core Structures In Rhizobium Etli And Mutants Deficient In O-Antigen, Russell W. Carlson, Bradley Reuhs, Tong-Bin Chen, U. Ramadas Bhat, K. Dale Noel

Biological Sciences Faculty Research and Publications

Lipopolysaccharide (LPS) is a major component of the bacterial outer membrane, and for Rhizobium spp. has been shown to play a critical role in the establishment of an effective nitrogen-fixing symbiosis with a legume host. Many genes required for O-chain polysaccharide synthesis are in the lps α region of the CE3 genome; this region may also carry lps genes required for core oligosaccharide synthesis. The LPSs from several strains mutated in the α region were isolated, and their mild acid released oligosaccharides, purified by high performance anion-exchange chromatography, were characterized by electrospray- and fast atom bombardment-mass spectrometry, NMR, and …

Quantitative Analysis Of Electrotonic Structure And Membrane Properties Of Nmda-Activated Lamprey Spinal Neurons, C. R. Murphey, L. E. Moore, James T. Buchanan

Biological Sciences Faculty Research and Publications

Parameter optimization methods were used to quantitatively analyze frequency-domain-voltage-clamp data of NMDA-activated lamprey spinal neurons simultaneously over a wide range of membrane potentials. A neuronal cable model was used to explicitly take into account receptors located on the dendritic trees. The driving point membrane admittance was measured from the cell soma in response to a Fourier synthesized point voltage clamp stimulus. The data were fitted to an equivalent cable model consisting of a single lumped soma compartment coupled resistively to a series of equal dendritic compartments. The model contains voltage-dependent NMDA sensitive (^INMDA), slow potassium (I_{K …}

In Vitro Evaluation Of Anti-Eimeria Tenella, Gamont-Specific, Monoclonal Antibodies And Partial Characterization Of Their Target Antigens, Eric Wilson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This study represents an effort to interrupt the life cycle of Eimeria tenella, the parasite that causes cecal coccidiosis in chickens, with a panel of 12 gamont-specific monoclonal antibodies (Mabs). To facilitate Mab screening, it was first necessary to develop a cell culture-adapted strain of E. tenella (field strain 80) from primary chicken kidney cells (PCKC) to white Leghorn chickens and back to PCKC. This alternation was repeated through 12 such passages. As a result, we have developed a cell culture-adapted strain of E. tenella that produces over 280% more oocysts in vitro than the original parent strain, and …

Functional Study Of The Structural Vp6 Protein Of Bluetongue Virus, Emiko Hayama

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This study was undertaken to investigate the structure-function relationship of VP6 protein of bluetongue virus (BTV) using molecular cloning techniques. VP6 is present in small quantities in BTV and its enzymatic activity and role in the viral replication cycle have not been studied. Since the availability of large amounts of purified VP6 is essential for the analysis of VP6, a BTV-11 S3 gene was cloned into a prokaryotic protein expression system. VP6 protein was expressed in large amounts and purified to near homogeneity. A series of C-terminal and internal deletion mutants of S3 gene was constructed and the truncated VP6 …

Cell Death In The Embryonic Developing Limb, J. M. Hurle, M. A. Ros, V. Garcia-Martinez, D. Macias, Y. Ganan

Scanning Microscopy

In amniote vertebrates, the development of form and structure of the limb bud is accompanied by precise patterns of massive mesodermal cell death with morphological features of apoptosis. These areas of cell death appear to eliminate undifferentiated cells which are required only for a limited time period of limb development. Predictable skeletal and morphological anomalies of the limb occur when the pattern of cell death is modified in mutant species or under experimental conditions. Most evidence points to the occurrence of local triggering mechanisms to account for the establishment of the areas of cell death and the subsequent activation of …

The Effects Of Dietary Vitamin E Supplementation On Platelet Aggregation And Plasma Oxidized Low Density Lipoprotein In Hypercholesterolemic Rats, Russell W. Thurman

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 by Russell W. Thurman on April 28, 1995.

Phytoplankton In Mt. St. Helens Lakes, Washington, Cynthia Fay Baker

Dissertations and Theses

Phytoplankton communities in fifteen lakes in the Mt. St. Helens area were surveyed to assess the abundance and species present. Eleven of the lakes were inside the blast zone of the 1980 eruption and four were located outside the blast zone as a comparison. The hypothesis is that lakes will cluster together based on the algal species present and that some algae will be correlated with certain environmental conditions. A cluster analysis was performed to determine if the lakes would group together based on algal abundance. There did not appear to be any distinct clustering among the study lakes, but …

Alterations In Mdck And Llc-Pk1 Cells Exposed To Oxalate And Calcium Oxalate Monohydrate Crystals, R. L. Hackett, P. N. Shevock, S. R. Khan

Scanning Microscopy

Structural analysis of human kidney stones reveals the presence of cellular membranes and other cell fragments. Experimentally, calcium oxalate crystallization is facilitated when an exogenous nephrotoxin is given with ethylene glycol, thus providing cellular degradation products to act as heterogenous nuclei. In this report, we tested whether oxalate alone could act as a cell toxin capable of producing damaged cells without the presence of an exogenous agent. Cultured LLC-PK₁ and MDCK cells, when exposed to 1.0 mmol KOx, a concentration at the limit of metastability for calcium oxalate nucleation, were severely damaged as measured by specific lactate dehydrogenase (LDH) …

Radiation Nephropathy: A Review, M. E. C. Robbins, S. M. Bonsib

Scanning Microscopy

The marked radiosensitivity of renal tissue represents a limitation on the total radiotherapeutic dose that safely can be applied to treatment volumes that include the kidneys. Radiation nephropathy is characterized by a progressive reduction in renal hemodynamics associated with a severe anemia. The latter is often normochromic normocytic in character, but can progress to a microangiopathic hemolytic anemia. The pathogenic mechanisms responsible for the development of radiation nephropathy remain ill-defined. Experimental studies which allow serial determinations of functional, morphologic, and cell kinetic radiation-induced changes indicate that primarily glomerular but also tubular alterations occur in the primary stages of radiation nephropathy. …

A New Scanning Electron Microscopy Approach To The Quantification Of Bone Mineral Distribution: Backscattered Electron Image Grey-Levels Correlated To Calcium Kα-Line Intensities, P. Roschger, H. Plenk Jr., K. Klaushofer, J. Eschberger

Scanning Microscopy

The introduction of backscattered electron (BSE) imaging in scanning electron microscopy (SEM) has led to new possibilities for the evaluation of mineral distributions in bone on a microscopic level. The different grey-levels seen in the BSE-images can be used as a measure for the local mineral content of bone. In order to calibrate these BSE-grey-levels (BSE-GL) and correlate them to mineral contents, various attempts, using reference samples with known weighted mean atomic number and/or using simulated bone tissues with known hydroxyapatite concentrations, have been made. In contrast, a new approach is presented here based on measurements of the X-ray intensities …

Carriage Rates Of The Nosocomial Pathogen Staphylococcus Aureus In Hospital Workers, Mark Peterson

Capstone Research Projects

In the 1950s, Staphylococcus aureus caused a worldwide epidemic of hospital acquired infections (nosocomial infections). By so doing, this bacterium forced nosocomial infections to be recognized as a major problem in the health care system. In that decade, it was discovered that Staphylococcus aureus is vectored by nurses in three different manners, and that carriage rates increase with length of clinical exposure to sources of the bacteria in the hospital environment.

Once subdued by antibiotics, multiple drug resistant strains of Staphylococcus aureus are again causing major nosocomial problems. In 1989, Cookson reported that a direct relationship exists between the degree …

Characterization And Expression Of Pseudomonas Fluorescens L-Arabinose Dehydrogenase: Genetic Elements In Pseudomonas Putida, Carol M. Wierenga

Masters Theses

An assay based on the spectrophotometeric properties of NAD/NADH was developed to detect the degradation of L-arabinose to L-arabinolactone. This assay was used to determine the expression of the L-arabinose utilization genes contained in Pseudomonas fluorescens and in the plasmid, designated pPZ221, contained in Pseudomonas putida. The results from this assay, in conjunction with various growth kinetics, indicate that pPZ221 is inducible and repressible for L-arabinose utilization. Thus, the P. fluorescens chromosomal insert in pPZ221 for L-arabinose utilization does appear to contain the regulatory genes necessary for controlling the expression of an L-arabinose operon.

Gold Coating Of Respiratory Cilia For Scanning Electron Microscopy, E. Toskala, J. Nuutinen, M. Rautiainen, A. Pelttari

Scanning Microscopy

The optimal thickness of gold coating of cilia for scanning electron microscopy was studied using respiratory mucosa obtained from pigs. We tested 8 different coating times, from 10 seconds to 4 minutes, which resulted in gold layer thicknesses varying from 16 ± 1 nm to 100 ± 3 nm. The thickness of the gold layer with a coating time of 60 seconds and voltage of 2.5 kV was 43 ± 5 nm. This thickness of gold layer gave good image quality without causing any electric charging. With thinner gold films, the amount of electric charging increased. When the coating time …

Early Elemental And Ionic Changes In Cultured Cells After Stimulation With Epidermal Growth Factor, Julian E. Beesley, Simon R. Hall, Martin J. Page, Karen Affleck

Scanning Microscopy

Stimulation of A43 l cells (a human vulval epidermal cell line) with 50 ng/ml of epidermal growth factor (EGF) in the presence of 1. 7 mM extracellular calcium produced a sharp and sustained rise in intracellular ionic Ca2+, increased elemental Na, decreased K and a rise in Ca. In the absence of extracellular calcium, the initial Ca2+ rise remained but the sustained elevation of intracellular Ca2+ was abolished, Na and K fluxes were variable and the Ca did not change. Increased Na and decreased K was marked at 2 minutes and returned to the control value after 60 minutes. The …

Scanning Electron Microscopic Observation Of Dark Cells After Streptomycin Perfusion Of The Vestibule In Guinea Pigs, Xianxi Ge, John J. Shea Jr.

Scanning Microscopy

Hearing has been stabilized in the majority of patients studied in the treatment of Meniere's disease with streptomycin. This observation suggests that effects of streptomycin may ameliorate endolymphatic hydrops, possibly by attenuating the activity of secretory tissue. The purpose of this study is to observe the dark cells of the utricle in guinea pigs after streptomycin perfusion of the vestibule. Twelve pigmented guinea pigs weighing 250-350 grams were used in this study. The vestibules in five guinea pigs were perfused monolaterally with 150 μg of streptomycin in artificial perilymph and, in seven, the vestibules were perfused only with artificial perilymph …

The Effects Of Diethyldithiocarbamate (Ddc) On The Astrocytic Cytoskeleton, Mary F. Mcmanus, Louis D. Trombetta

Scanning Microscopy

The dithiocarbamates are a group of compounds that are used extensively in industry, agriculture and medicine. Exposure to these compounds has caused deleterious effects to both the central and peripheral nervous systems. Cultured rat hippocampal astroglia treated with 35 μg/ml diethyldithiocarbamate (DDC) in media were studied for alterations to the cytoskeleton. Examination by both immunohistochemistry and scanning electron microscopy revealed disruption of the cytoskeletal elements. This occurred in a progressive time-dependent manner. Electrophoretic patterns demonstrated two cytoskeletal protein alterations. The microtubular protein, β-tubulin, appeared to have an altered mobility while the major intermediate filament protein, glial fibrillary acidic protein (GF …

Gold, Electron Microscopy, And Cancer Therapy, James F. Hainfeld

Scanning Microscopy

Radioactive gold has properties suitable for radiotherapy and can provide lethal irradiation to cells. If the gold is conjugated to a targeting molecule, such as an antibody, it may be possible to specifically deliver the dose to tumor cells. Various gold particles are possible candidates and include gold colloids with adsorption of antibodies or gold clusters with covalent attachment. Different sizes of gold particles are available and some may be preferred for certain situations. Problems with intravenous injection and in vivo delivery are numerous, and a more tractable application is the direct instillation into the urinary bladder of radiogold immunoconjugates …

Swift Heavy Ion Induced Electron Emission From Solids, Hermann Rothard

Scanning Microscopy

Quite a number of experiments have been performed on electron emission from solids induced by slow (projectile velocity Vp < 1 atomic unit) or medium velocity heavy ions (projectile energy Ep < 1 MeV/u). Only a few experiments have been made with fast heavy ions (projectile atomic number Zp > 8, Ep > 2 MeV/u) concerning either electron emission yields -y, or double differential electron energy spectra d2n(0)/dEd0 as a function of the observation angle 0. We present the results obtained so far on electron emission induced by fast (Ep > 2 MeV/u) heavy ions (Zp ~ 6). Topics discussed include experimental results for electron yields, -energy and -angular distributions and channelling phenomena as well as the theoretical approaches. We also present new results from recent studies on the evolution of electron yields …

Semiquantitative Analysis By Scanning Electron Microscopy Of Cochlear Hair Cell Damage By Ototoxic Drugs, Takehisa Saito, Yasuhiro Manabe, Noriyuki Honda, Takechiyo Yamada, Takehito Yamamoto, Hitoshi Saito

Scanning Microscopy

The ototoxicity of cisplatin and carboplatin in the organ of Corti of the guinea pig was evaluated semiquantitatively. Damage of the stereocilia of outer hair cells (OHCs) observed by scanning electron microscopy (SEM) was classified into normal, grade 1 (10-50% loss of stereocilia), grade 2 (less than 50% remaining stereocilia), or grade 3 (missing stereocilia). The OHCs observed by light microscopy (LM) were classified as remaining or missing cells. Fifty OHCs of each row in the middle part of each turn of the cochlea were counted (a total of 150 cells per turn). Guinea pigs were administered 5 mg/kg of …

Structure Of The First C2 Domain Of Synaptotagmin I: A Novel Ca(2+)/Phospholipid-Binding Fold, R. Bryan Sutton, Bazbek A. Davletov, Albert M. Berghuis, Thomas C. Sudhof, Stephen R. Sprang

Biological Sciences Faculty Publications

C₂ domains are regulatory sequence motifs that occur widely in nature. Synaptotagmin I, a synaptic vesicle protein involved in the Ca²⁺ regulation of exocytosis, contains two C₂ domains, the first of which acts as a Ca²⁺ sensor. We now describe the three-dimensional structure of this C₂ domain at 1.9 Å resolution in both the Ca²⁺-bound and Ca²⁺-free forms. The C₂ polypeptide forms an eight-stranded β sandwich constructed around a conserved four-stranded motif designated as a C₂ key. Ca²⁺ binds in a cup-shaped depression between two polypeptide loops located …

Comparison Of Cell Sediment And Surface Grown "Test Plaque" Using Scanning Electron Microscopy, S. M. Mccormack, C. M. D. Maran, K. M. Scott-Anne, D. T. Zero

Scanning Microscopy

Scanning electron microscopy was used to compare the morphology, integrity and distribution of bacterial cells in a test plaque grown on the surface of enamel with that of the cell sediment plaque routinely used in a short-term intraoral caries model. Cultures of S. mutans IB-1600 or S. sobrinus 6715-13 were grown in complex media supplemented with either 2.0% sucrose (glucan plaque) or 0.2 % glucose (non-glucan plaque). Cell sediment (CS) plaque was prepared by centrifuging the cultures after incubation, recovering the cell sediment, and spreading it on Metricel membrane filter paper. Surface grown (SG) plaque was prepared by suspending saliva-coated …

Effect Of Sodium Saccharin On The Neonatal Rat Bladder, Samuel M. Cohen, Martin Cano, Margaret K. St. John, Emily M. Garland, Mohamad Khachab, Leon B. Ellwein

Scanning Microscopy

In a two-generation bioassay, high doses of dietary sodium saccharin (NaSac) produce bladder carcinoma in rats, whereas acid saccharin (HSac) does not effect the urothelium. NaSac and HSac administered as 5% of the diet to F0 Sprague-Dawley (SD) and F344 rats, continued through to the weaned male rats for ten additional weeks. Control 3H-thymidine labeling index (LI) was high prior to and at birth (approximately 11%), declining rapidly by weaning (to < 0.2). Neither NaSac nor HSac increased proliferation through 7 days of age. NaSac increased the proliferation rate at later times, whereas HSac did not. The LI decreased to control levels in NaSac-fed rats switched to control diet after weaning and increased in control-fed rats switched to NaSac after birth or weaning. In a second experiment, 5% NaSac did not affect urothelial morphology of SD rats through 7 days. By 21 days post-birth, urothelial hyperplasia occurred in NaSac-fed rat. The LI in treated versus control was similar through gestation, with a slight difference by 7 days. LI was significantly different by 21 days post-birth, but was similar between males and females. These results provide additional evidence for the increased cell proliferative effects of NaSac during the neonatal period, but not during gestation.

Three-Dimensional Configuration Of Crypts Of Different Types Of Colorectal Adenomas, Keijiro Araki, Takuro Ogata

Scanning Microscopy

The three-dimensional configuration of isolated crypts of normal human colonic mucosa and colorectal adenomas was examined by scanning electron microscopy. For isolation of the crypts, the digestion method with HCl was used for formalin fixed tissues, and the separation method with ethylenediaminetetraacetic acid (EDT A) following ultrasonication was applied to fresh tissues. In a comparative study, the NaOH cell-maceration method, which visualized the sub-basal laminal collagen sheath, was applied. The isolated crypts from the normal colon were visualized as a single straight tubule resembling a test tube. Most isolated crypts of the tubular adenomas were visualized as elongated fan-like structures …