Biochemistry, Biophysics, and Structural Biology Commons^™

Agswe1p Regulates Mitosis In Response To Morphogenesis And Nutrients In Multinucleated Ashbya Gossypii Cells, Hanspeter Helfer, Amy S. Gladfelter

Dartmouth Scholarship

Nuclei in the filamentous, multinucleated fungus Ashbya gossypii divide asynchronously. We have investigated what internal and external signals spatially direct mitosis within these hyphal cells. Mitoses are most common near cortical septin rings found at growing tips and branchpoints. In septin mutants, mitoses are no longer concentrated at branchpoints, suggesting that the septin rings function to locally promote mitosis near new branches. Similarly, cells lacking AgSwe1p kinase (a Wee1 homologue), AgHsl1p (a Nim1-related kinase), and AgMih1p phosphatase (the Cdc25 homologue that likely counteracts AgSwe1p activity) also have mitoses distributed randomly in the hyphae as opposed to at branchpoints. Surprisingly, however, …

Ferritin: Mechanistic Studies And Electron Transfer Properties, Bo Zhang

Theses and Dissertations

Ferritins are ubiquitous iron storage proteins in living systems. Although much is known about the iron deposition process in ferritin and a mechanism has been developed, several important issues still remain unknown. One lingering question is the less than stoichiometric quantities of hydrogen peroxide detected in previous studies on animal ferritins. Extensive experimental data on identifying the species in competition for peroxide equivalents point to a surprising conclusion that H2O2 generated in the ferroxidase reaction is consumed by amine buffers that are commonly employed in in vitro ferritin studies, while non-nitrogen containing buffers, such as acetate, phosphate, and carbonate, do …

Cell Edge Features Affected By Microtubule Inhibitor Combinations, Sonal Uppal, Nancy Boudreau, Elizabeth Wendt, Carol Heckman

Applied Statistics and Operations Research Faculty Publications

The tumor promoter, phorbol 12-myristate 13-acetate (PMA), enhances tumor yield through an epigenetic mechanism. PMA, like another promoter, phosphatase inhibitor okadaic acid, works by maintaining proteins in a phosphorylated state. In order to identify chemicals with promoter and antipromoter effects, this laboratory has developed a standard curve of morphogenetic changes using data from precancerous cell lines that eventually became neoplastic. Using the curve as a basis of comparison, we defined the “signature” phenotype as that adopted when a cell line became neoplastic. The results of solving for signature type disclosed that the microtubule-depolymerizing compound, colchicine, had a promoter-like effect [2]. …

Immunogenicity Of Terephthalate, A Constituent Of Synthetic Polymers, And Its Modulation By Adjuvants, Youssef Aachoui

All-Inclusive List of Electronic Theses and Dissertations

Objective: In this study we have focused on the potential immunotoxicity resulting from exposure to phthalate compounds which are widely present as basic constituents of many synthetic polymers.

Myod Synergizes With The E-Protein Heb Beta To Induce Myogenic Differentiation, Maura H. Parker, Robert L.S. Perry, Melanie C. Fauteux, Charlotte A. Berkes, Michael A. Rudnicki

Biology Faculty Publications

The MyoD family of basic helix-loop-helix transcription factors function as heterodimers with members of the E-protein family to induce myogenic gene activation. The E-protein HEB is alternatively spliced to generate alpha and beta isoforms. While the function of these molecules has been studied in other cell types, questions persist regarding the molecular functions of HEB proteins in skeletal muscle. Our data demonstrate that HEB alpha expression remains unchanged in both myoblasts and myotubes, whereas HEB beta is upregulated during the early phases of terminal differentiation. Upon induction of differentiation, a MyoD-HEB beta complex bound the E1 E-box of the myogenin …

Photoreductive Dissolution Of Ferrihydrite By Methanesulfinic Acid: Evidence Of A Direct Link Between Dimethylsulfide And Iron-Bioavailability, Anne M. Johansen, Jennifer M. Key

All Faculty Scholarship for the College of the Sciences

Within open‐ocean regions where excess macronutrients are present, phytoplankton growth is limited by the bioavailability of iron supplied to these areas primarily within atmospheric aerosols of crustal origin. However, processes that control the abundance of biologically accessible iron in these aerosols are largely unknown. Here we show that dissolution of ferrihydrite, a surrogate iron(oxy)hydroxide phase found in atmospheric waters, is enhanced in the presence of methanesulfinic acid (MSIA, CH₃SO₂H, a dimethylsulfide (DMS) oxidation intermediate) in laboratory irradiation experiments with aqueous suspensions that simulate marine aerosol particles. The increased release of soluble Fe(II) is attributed to a …

Structure-Activity Studies Of Glycosphingolipids As Antigens Of Natural Killer T Cells, Randal Donald Goff

Theses and Dissertations

Glycosphingolipids (GSLs), composed of a polar saccharide head and a lipophilic ceramide tail, are ubiquitous components of the plasma membrane of eukaryotic cells. They serve in many regulatory capacities and have antigenic properties towards natural killer T (NKT) cells of the innate immune system. Critical to the recognition of glycosylceramides by NKT cells are antigen presenting cells (APC), such as dendritic cells, which are responsible for binding, processing, and delivery of ligands to these lymphocytes. This event is mediated by CD1d, a major histocompatibility complex-like protein expressed on the surface of APCs, which binds GSL antigens by the ceramide moiety …

Accumulation Of Phycotoxins In The Mussel Mytilus Galloprovincialis From The Central Adriatic Sea, Maja Pavela-Vrančić, Ivana Ujević, Živana Ninčević Gladan, Ambrose Furey

Physical Sciences Publications

Surveys of DSP (Diarrheic Shellfish Poisoning) toxin profiles in the mussel Mytilus galloprovincialis from coastal waters of the central Adriatic Sea, over the years 1995 to 2001, demonstrate that incidents of shellfish toxicity in this area are dominated by the occurrence of okadaic acid (OA) and a PTX derivative, 7-epi-pectenotoxin-2-seco acid (7-epi-PTX-2SA). Toxin composition and the relative ratio of toxic components in shellfish is in correlation with the occurrence of DSP producing organisms from the Dinophysis species along with Prorocentrum micans and Lingulodinium polyedrum. The occurrence of D. sacculus shortly before the appearance of OA in shellfish implicates its possible …

The Effect Of Protein Dielectric Coefficient On The Ionic Selectivity Of A Calcium Channel, Douglas Henderson, Dezso Boda, Monika Valisko, Bob Eisenberg, Wolfgang Nonner, Dirk Gillespie

Faculty Publications

Calcium-selective ion channels are known to have carboxylate-rich selectivity filters, a common motif that is primarily responsible for their high Ca2+ affinity. Different Ca2+ affinities ranging from micromolar (the L-type Ca channel) to millimolar (the ryanodine receptor channel) are closely related to the different physiological functions of these channels. To understand the physical mechanism for this range of affinities given similar amino acids in their selectivity filters, we use grand canonical Monte Carlo simulations to assess the binding of monovalent and divalent ions in the selectivity filter of a model Ca channel. We use a reduced model where the electrolyte …

Dna-Templated Surface Alignment And Characterization Of Carbon Nanotubes., Huijun Xin

Theses and Dissertations

Carbon nanotubes are appealing materials for nanofabrication due to their unique properties and structures. However, for carbon nanotubes to be used in mass-fabricated devices, precise control of nanotube orientation and location on surfaces is critical. I have developed a technique to align single-walled carbon nanotubes (SWNTs) on surfaces from a droplet of nanotube suspension under gas flow. Fluid motion studies indicate that alignment is likely due to circulation of SWNTs in the droplet. My work provides a facile method for generating oriented nanotubes for nanodevice applications. I have also devised an approach for localizing SWNTs onto 1-pyrenemethylamine-decorated DNA on surfaces. …

Development Of An In Vitro Protocol To Study The Effect Of Estrogen On Osteoblast Activity, Sourik Ganguly

Morehead State Theses and Dissertations

A thesis presented to the faculty of the College of Science & Technology at Morehead State University in partial fulfillment of the requirements for the Degree of Master of Science by Sourik Ganguly on July 7, 2006.

Enhanced Electrospray Ionization For Mass Spectrometry And Ion Mobility Spectrometry, Li Zhou

Theses and Dissertations

Electrospray ionization (ESI) has become one of the most commonly used ionization techniques for mass spectrometry (MS) and ion mobility spectrometry (IMS), and efforts continue to improve its performance. ESI-MS is most recognized for its wide application to biomacromolecules where high sensitivity is of paramount importance. However, the major limitation in sensitivity with ESI-MS is due to its low ion transmission efficiency from the ESI source into the sampling orifice and through any stages utilized for transfer of ions from atmosphere to vacuum in the MS. A series of atmospheric pressure ion focusing interfaces were designed and implemented to enhance …

Electric Field Gradient Focusing-Uv Detection For Protein Analysis, Shu-Ling Lin

Theses and Dissertations

Electric field gradient focusing (EFGF) utilizes a hydrodynamic flow and an electric field gradient to focus and concentrate charged analytes and order them in a separation channel according to electrophoretic mobility. Elution can be achieved by decreasing the applied voltage or increasing the hydrodynamic flow. EFGF has the advantages of concentrating a large volume (100 micro-L) of target proteins without significant band broadening and simultaneously removing unwanted components from the sample. Two types of EFGF devices have been investigated to concentrate and separate proteins: a fiber-based EFGF device and a hydrogel-based EFGF device. Using fiber-based EFGF with UV detection, a …

Molecular Modeling Of Proteins And Peptides Related To Cell Attachment In Vivo And In Vitro, Wanhua Zhao

Doctoral Dissertations

Polypeptides constitute half of the dry mass of the cell, they form the bulk of the extracellular matrix (ECM), and they are a common element of extra- and intracellular signaling pathways. There is increasing interest in the development of computational methods in polypeptide and protein engineering on all length scales. This research concerns the development of computational methods for study of polypeptide interactions related to cell attachment in vivo and in vitro.

Polypeptides are inherently biocompatible, and an astronomical range of unique sequences can be designed and realized in massive quantities by modern methods of synthesis and purification. These …

Concurrent Expression Of Hyaluronan Biosynthetic And Processing Enzymes Promotes Growth And Vascularization Of Prostate Tumors In Mice, Melanie A. Simpson

Department of Biochemistry: Faculty Publications

Aggressive cells in prostate cancer secrete extracellular hyaluronan (HA) as a result of up-regulated HA synthase enzymes HAS2 and HAS3. Combined detection of HA and the HA processing hyaluronidase enzyme Hyal1 in prostate tumors correlates with poor outcome. HA oligomers produced by hyaluronidases are potent angiogenic stimuli. We investigated the respective roles of HAS2 and Hyal1 using 22Rv1 human prostate tumor cells that lack both enzyme activities. Stable transfectants were selected for overexpression of Hyal1 or HAS2 and for coexpression of Hyal1 and HAS2. HAS2 overexpression elevated HA production and excess pericellular HA retention. However, HAS2-transfected tumor cell growth in …

Chemical Evidence For Dietary Toxin Sequestration In The Asian Snake Rhabdophis Tigrinus, Deborah A. Hutchinson

Biological Sciences Theses & Dissertations

Rhabdophis tigrinus (Colubridae: Natricinae) is an oviparous, bufophagous (toad-eating) snake from eastern Asia that possesses defensive integumentary glands on the neck known as nuchal glands. These glands are used in antipredator displays and typically contain bufadienolide toxins. Whereas toads are known to synthesize bufadienolide steroids from cholesterol precursors, we found that chemically undefended R. tigrinus must sequester bufadienolides from ingested toads in order to exhibit these compounds in their nuchal glands. Chemically defended females are capable of provisioning their embryos with these toxins so their unfed hatchlings possess defensive bufadienolides prior to consuming toads themselves. All of the hatchling R. …

Visualization Of Intracellular Transport Of Vesicular Stomatitis Virus Nucleocapsids In Living Cells, Subash C. Das, Debasis Nayak, You Zhou, Asit K. Pattnaik

School of Veterinary and Biomedical Sciences: Faculty Publications

The phosphoprotein (P) of vesicular stomatitis virus (VSV) is a subunit of the viral RNA polymerase. In previous studies, we demonstrated that insertion of 19 amino acids in the hinge region of the protein had no significant effect on P protein function. In the present study, we inserted full-length enhanced green fluorescent protein (eGFP) in frame into the hinge region of P and show that the fusion protein (PeGFP) is functional in viral genome transcription and replication, albeit with reduced activity. A recombinant vesicular stomatitis virus encoding PeGFP in place of the P protein (VSV-PeGFP), which possessed reduced growth kinetics …

Is There A Twenty Third Amino Acid In The Genetic Code?, Alexey V. Lobanov, Gregory V. Kryukov, Dolph L. Hatfield, Vadim Gladyshev

Vadim Gladyshev Publications

The universal genetic code includes 20 common amino acids. In addition, selenocysteine (Sec) and pyrrolysine (Pyl), known as the twenty first and twenty second amino acids, are encoded by UGA and UAG, respectively, which are the codons that usually function as stop signals. The discovery of Sec and Pyl suggested that the genetic code could be further expanded by reprogramming stop codons. To search for the putative twenty third amino acid, we employed various tRNA identification programs that scanned 16 archaeal and 130 bacterial genomes for tRNAs with anticodons corresponding to the three stop signals. Our data suggest that the …

Extracellular Superoxide Dismutase Protects Cardiomyocytes During Hyperoxia, Mervat Elsayed Ali

Theses and Dissertations in Biomedical Sciences

Reactive oxygen species are implicated in tissue damage in many cardiovascular diseases. The current study was designed to test the hypothesis that exposure to high inspired oxygen concentrations (100%) damages cardiac mitochondria and that a biogenic response is needed for cell survival. The study was done in mice with a transgene (TG) for extracellular superoxide dismutase (EC-SOD) or with the EC-SOD gene knockout (KO). Adult EC-SOD mice and their wild type littermates and EC-SOD KO mice and their wild type littermates were exposed to 100% oxygen for 6 hours and for 72 hours, and the hearts were subsequently removed under …

Model Studies Towards The Total Synthesis Of Lyconadin A Via An Acyl Radical Cascade Reaction, Koudi Zhu

Theses and Dissertations

Lyconadin A is an alkaloid possessing a unique structure and antitumor activity. The total synthesis of Lyconadin A was proposed via an acyl radical cascade reaction. To investigate the possibility and stereoselectivity of the cascade cyclization, phenyl selenoester 16 was chosen as a model substrate to study the 7-exo-5-exo radical cyclization. A synthetic route to phenyl selenoester 16 was developed. The 7-exo-5-exo radical cyclization was found to occur with a high yield and excellent stereoselectivty. Attempts were also tried to synthesize another radical precursor 14 albeit with less success. A synthetic pathway to the synthesis of 14 as well as …

"Preface" To Selenium: Its Molecular Biology And Role In Human Health, Second Edition, Dolph L. Hatfield, Marla J. Berry, Vadim N. Gladyshev

Vadim Gladyshev Publications

The purpose of the new edition book is to inform the reader of many new discoveries and to examine our present knowledge of the molecular biology of selenium, its incorporation into proteins as selenocysteine and the role that this element and selenium-containing proteins (selenoproteins) play in health. The book's emphasis is on our understanding of selenium metabolism in mammals and the role of this element in human health. The book begins with a brief history of selenium and how its face has changed through the years fiom one of a toxin and possible carcinogen to one of an essential micronutrient …

Selenoproteins And Selenoproteomes, Vadim N. Gladyshev

Vadim Gladyshev Publications

In the past several years, progress in genome sequencing and development of specialized bioinformatics tools allowed efficient identification of selenocysteine-containing proteins encoded in completely sequenced genomes. Information is currently available on selenoproteomes from a variety of organisms, including humans, which contain 25 known selenoprotein genes. This review provides basic information about mammalian selenoproteins and other known selenoprotein families. Analysis of full sets of selenoproteins in organisms provides exciting avenues for examining selenoprotein evolution and dependence of organisms on the trace element selenium and allows linking selenoproteins with specific biological and biomedical effects of dietary selenium.

Mouse Models For Assessing The Role Of Selenoproteins In Health And Development, Bradley A. Carlson, Xue-Ming Xu, Rajeev Shrimali, Aniruddha Sengupta, Min-Hyuk Yoo, Nianxin Zhong, Dolph L. Hatfield, Robert Irons, Cindy D. Davis, Byeong Jae Lee, Sergey V. Novoselov, Vadim N. Gladyshev

Vadim Gladyshev Publications

Mouse models have been generated to assess the roles of selenoproteins involved with housekeeping tasks and/or stress-related phenomena in development and health. Each mouse model has taken advantage of the fact that the synthesis of all selenoproteins is dependent on the expression of two selenocysteine ^{(Sec) tRNA[Ser]Sec} isoforms that differ fiom each other by a single methyl group on the ribosyl moiety at position 34. The endogenous ^{(Sec) tRNA[Ser]Sec} population was selectively altered by generating mouse models involving 1) transgenic animals carrying mutant or wild type ^{(Sec) tRNA[Ser]Sec} transgenes, 2) conditional knockout animals carrying a floxed ^{(Sec) tRNA[Ser]Sec} gene that …

Selenium And Methionine Sulfoxide Reduction, Hwa-Young Kim, Vadim N. Gladyshev

Vadim Gladyshev Publications

Methionine residues in proteins can be readily oxidized to a diastereomeric mixture of methionine sulfoxides by reactive oxygen species. In most organisms, methionine sulfoxides are reversibly and stereospecifically reduced back to methionine by two distinct classes of repair enzymes, methionine-S-sulfoxide reductase (MsrA) and methionine-R-sulfoxide reductase (MsrB). Methionine sulfoxide reduction is thought to be an essential pathway that protects cells from oxidative stress and regulates protein function. This pathway is also implicated in delaying the aging process in organisms from yeast to mammals. The first selenoprotein identified using bioinformatics methods, SelR (also known as SelX or MsrB1), was recently found to …

Evolution Of Selenocysteine Decoding And The Key Role Of Selenophosphate Synthetase In The Pathway Of Selenium Utilization, Gustavo Salinas, Héctor Romero, Xue-Ming Xu, Bradley A. Carlson, Dolph L. Hatfield, Vadim N. Gladyshev

Vadim Gladyshev Publications

The complete sequencing of genomes and the development of in silico methods for identification of genes encoding selenocysteine (Sec)-containing proteins have greatly contributed to shape our view on the evolution of selenium utilization in nature. Current evidence is consistent with the idea that Sec decoding is a late addition to the genetic code and it evolved once, before the separation of archaeal, bacterial and eukaryal domains. Many organisms have lost the Sec decoding trait, but recent evidence has shown that the loss is not irreversible. The distribution of organisms that use UGA as a Sec codon suggests that Sec decoding …

Selenoproteins In Parasites, Gustavo Salinas, Alexei V. Lobanov, Vadim N. Gladyshev

Vadim Gladyshev Publications

Parasites, which cause an enormous burden in the population of the third world, are a diverse group of organisms, many of which are sensitive to oxidative stress imposed by their hosts. In recent years, several selenoprotein families, some with antioxidant properties, have been described and characterized in metazoan parasites. Glutathione peroxidase and thioredoxin glutathione reductase (TGR) appear to be essential selenoproteins in flatworms (phylum Platyhelminthes). TGR is the single enzyme that provides reducing equivalents to both thioredoxin and glutathione pathways, in contrast to hosts, which evolve parallel pathways. In roundworms (phylum Nematoda), selenoproteins have recently been described, revealing …

The 15-Kda Selenoprotein (Sep15): Functional Analysis And Role In Cancer, Vyacheslav M. Labunskyy, Vadim N. Gladyshev, Dolph L. Hatfield

Vadim Gladyshev Publications

The 15-kDa selenoprotein (Sep15) was identified several years ago as a protein of unknown function. In recent years, several lines of evidence implicated Sepl5 in the effect of dietary selenium in cancer prevention. These lines of evidence include: 1) protein expression patterns in normal and malignant cells; 2) identification of polymorphic sites that regulate Sep15 levels and differentially respond to selenium supplementation; 3) location of the Sep15 gene in the human genome; and 4) correlation between Sep15 haplotype and susceptibility to cancer. Functional analyses revealed a specific interaction between Sep15 and a protein folding sensor in the endoplasmic reticulum of …

Mammalian And Other Eukaryotic Selenocysteine Trnas, Bradley A. Carlson, Xue-Ming Xu, Rajeev Shrimali, Aniruddha Sengupta, Min-Hyuk Yoo, Robert Irons, Nianxin Zhong, Dolph L. Hatfield, Byeong Jae Lee, Alexei V. Lobanov, Vadim N. Gladyshev

Vadim Gladyshev Publications

Selenocysteine (Sec) tRNA occupies a prominent position in the expression of selenoproteins as it is essential for their synthesis and it provides the means by which selenium is co-translationally inserted into protein as the amino acid, Sec. Thus, Sec tRNA is regarded as the principle constituent in selenoprotein synthesis. Many features unique to this tRNA have been characterized over the years in mammals and other eukaryotes. In the last five years, the major advances have been in an elucidation of the different roles that the two major Sec tRNA isoforms play in selenoprotein biosynthesis and in Sec biosynthesis. One isoform …