310,045 research outputs found
Implication du ppGpp et du régulateur global CodY dans le déclenchement de la compétence chez streptococcus pneumoniae
No full textStreptococcus pneumoniae (le pneumocoque) est une bactérie commensale, présente de façon asymptomatique dans le rhinopharynx de 20 % d'adultes et 50 % d'enfants. Cette bactérie peut devenir un pathogène majeur responsable de pneumonies, de méningites et de septicémies, et cause 1,5 million de morts chaque année dans le monde. Il existe deux méthodes de lutte : l'antibiothérapie et la vaccination. Ces deux stratégies se heurtent à la grande variabilité génétique du pneumocoque, essentiellement due à sa capacité à transformer naturellement. La transformation requiert le développement d'un état physiologique transitoire appelé compétence. Sa régulation met en jeu une boucle autocatalytique conduisant à l'expression des gènes de compétence. Mon travail de thèse a porté sur l'étude des mécanismes moléculaires responsables de l'initiation de la compétence. Des études menées au laboratoire ont montré l'implication indirecte de Ami (transport d'oligopeptides) dans la répression de la compétence. Les acides aminés transportés par Ami pourraient servir de jauge métabolique sentie par RelA (réponse stringente) ou par CodY. Nos résultats montrent que le ppGpp est un activateur de la compétence, mais cette molécule n'est pas le seul signal aboutissant au développement de la compétence, et que CodY pourrait être un répresseur de la compétence. De plus, nous avons montré que codY est essentiel et que son inactivation peut aboutir à la formation de structures mérodiploïdes. De plus, l'absence de CodY peut être compensée par la présence de 2 mutations, fatC et amiC, ou par d'autres mutations qui n'ont pas encore été identifiées.Streptococcus pneumoniae (the pneumococcus) is found in the nasopharynx of 20% of adults and 50% of children. The pneumococcus is a major pathogen, causing pneumonia, otitis media, meningitis and bacteriema. Every year, pneumococcal infections kill 1.5 million people worldwide. The two methods used to fight this pathogen (vaccination and antibiotherapy) can be bypassed by the high genetic variability of the pneumococcus. Natural genetic transformation is responsible for this variability and requires the pneumococcus to enter a transitory physiological state called competence. This state is based on an autocatalytic loop that induces the expression of the genes involved in competence. This thesis focusses on molecular mecanisms that lead to competence initiation in the pneumococcus. Studies carried out in our lab have shown that the Ami transporter is involved in competence regulation. Amino acids (intrenaliszed throught Ami) may be a metabolic gauge for competence regulation. Results show that ppGpp is involved in competence development activation but that other regulatory signals are also involved. The regulator CodY might be a competence repressor. On the other hand, this study has shown that codY is an essential gene and that its inactivation can lead to merodiploid formation. Furthermore, the absence of CodY can be compensated by the presence of two mutations, in the fatC and amiC genes, or by the presence of other mutations not yet characterized
Letter, Jerome E. Klein to Cody Fowler, January 5, 1960
No full textA letter from Jerome E. Klein to Cody Fowler inviting Fowler to nominate Progress Village to apply for the Lane Bryan Annual Awards for Volunteer Service to the Community.https://digitalcommons.usf.edu/progress_village_records/1090/thumbnail.jp
Cody Isbell, throwing football
No full textAthletics - Football - Players; Cody Isbell, Purdue End (Quarterback?)Intercollegiat
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Cody Isbell, catching football
No full textAthletics - Football - Players; Cody Isbell, Purdue End (Quarterback?); Photo by J.C. Allen and Son, W. Lafayette, Indiana (two copies)Intercollegiat
The marriage record of Cody, George and Johnson, Mary E
No full textMarriage license for George Cody and Mary E. Johnson. D.J. Young was the officiant
CodY—A substrate of PrkC and PrpN.
No full text(A) Coomassie stained gel image of CodY elution’s from BAS WT and BAS ΔprpN. (B) and (C) Representative immunoblots and bar graph showing phosphorylation status of CodY protein purified from indicated strains. Equal amounts (1 μg) of purified CodY proteins were loaded and probed using anti-phosphoserine. The same blot was stripped and probed again using anti-CodY. Indicated MWs were derived from adjacent lanes containing PageRuler Prestained Protein Ladder, Thermo Scientific (Cat. No. 26616). Densitometer analysis were done using Amersham Imager600 software and the corresponding phosphoserine/CodY ratio with respect to BAS WT were plotted in a bar graph using GraphPad Prism. Average values and standard deviations calculated from five independent experiments are shown in the bar graph. Asterisks indicate statistical significance of the data set calculated using two-tailed Student’s t test. *** corresponds to pprpN strain by PrpN treatment. (E and F) PrkC mediated phosphorylation of CodY. (E) Representative immunoblots and Ponceau-S stained image of in-vitro kinase assay performed using autophosphorylated PrkCcat and CodY. (F) Co-expression of CodY-His6 with and without PrkCcat. Proteins were resolved on SDS-PAGE and visualized using Pro-Q diamond phospho specific gel stain to examine the phosphorylation status (upper image) and Coomassie stain to confirm loading pattern (lower image). Lane 1: CodY-His6 produced in E. coli using pETDuet without PrkCcat; Lane 2: CodY-His6 produced using pETDuet with PrkCcat; Lane 3 and 4: CodY-His6 produced using pProEXHTc. Indicated MWs were derived from adjacent lanes containing PageRuler Prestained Protein Ladder, Thermo Scientific (Cat. No. 26616).</p
Design and synthesis of novel FtsZ-targeting antibacterial agents
No full textBacterial infections pose a major health concern worldwide, and the emergence of multi-drug resistant strains of bacteria has intensified the search for new antibiotic treatments with novel mechanisms of action. Bacterial cell division remains a new, currently untargeted pathway making it highly desirable research area for discovering new ways to kill bacteria. FtsZ is a highly conserved, essential bacterial cell division protein that forms the dynamic Z-ring involved in recruitment of other essential proteins and serving as the constricting force for cell division. Inhibiting the function of this key protein disrupts proper cell division, and has therefore become a key target in the search for new antibiotics. There are many known FtsZ inhibitors spanning from natural products such as sanguinarine and berberine, to synthetic derivatives such as GTP analogs and PC190723. The majority of these known inhibitors, however, lack the proper potency, safety profiles, and physiochemical properties required for clinical development. Initial studies involved modifying the structures of two known FtsZ inhibitors, sanguinarine and berberine, to increase potency and explore the structure-activity relationships. Unfortunately, although successfully obtaining analogs with good antibacterial activity, these compounds lacked desired solubility properties for further advancement. This led to the second generation of compounds that lacked a constitutive cationic charge while retaining the antibacterial activity seen with the previous analogs. While these compounds had much better solubility, they possessed a new drawback. Compounds from the second generation were found to be highly protein bound resulting in a significant loss of antibacterial activity when administered in the presence of protein. Studies began to design and synthesize analogs that either exhibited much higher potency or much less protein binding. Although initial attempts at this were unsuccessful, continued efforts are being made to find a FtsZ inhibitor with improved potency, physiochemical properties, and a broader spectrum of antibacterial activity.Ph. D.Includes bibliographical referencesby Cody Kelle
Myosin-cross-reactive antigen (MCRA) protein from Bifidobacterium breve is a FAD-dependent fatty acid hydratase which has a function in stress protection
No full textpeer-reviewedBackground The aim of this study was to determine the catalytic activity and physiological role of myosin-cross-reactive antigen (MCRA) from Bifidobacterium breve NCIMB 702258. MCRA from B. breve NCIMB 702258 was cloned, sequenced and expressed in heterologous hosts (Lactococcus and Corynebacterium) and the recombinant proteins assessed for enzymatic activity against fatty acid substrates. Results MCRA catalysed the conversion of palmitoleic, oleic and linoleic acids to the corresponding 10-hydroxy fatty acids, but shorter chain fatty acids were not used as substrates, while the presence of trans-double bonds and double bonds beyond the position C12 abolished hydratase activity. The hydroxy fatty acids produced were not metabolised further. We also found that heterologous Lactococcus and Corynebacterium expressing MCRA accumulated increasing amounts of 10-HOA and 10-HOE in the culture medium. Furthermore, the heterologous cultures exhibited less sensitivity to heat and solvent stresses compared to corresponding controls. Conclusions MCRA protein in B. breve can be classified as a FAD-containing double bond hydratase, within the carbon-oxygen lyase family, which may be catalysing the first step in conjugated linoleic acid (CLA) production, and this protein has an additional function in bacterial stress protection
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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