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2. Physiology and biochemistry of amidase production by Methylophilus methylotrophus

Author

Silman, Nigel James

Subjects
572, Biochemistry
Abstract

The physiological regulation of amidase production by Methylophilus methylotrophus was studied following growth of the organism under various conditions of nutrient sufficiency and limitation in batch, fed-batch and continuous cultures. Amidase was severely repressed by ammonia, and was induced by short chain aliphatic amides. Growth of the wild-type organism in acetamide-1imited continuous culture led to the selection of a hyperactive strain , the subsequent growth of which under acrylamide limitation led to the production of another strain (MM8) which exhibited even higher activities. Chemical mutagenesis of strain MM8 followed by growth in acrylamlde-limited continuous culture led to the selection of a strain (MM15) which continued to overexpress amidase, but which exhibited a low amidase activity and a greatly decreased Km for acrylamide. Determination of the concentrations of the enzyme revealed that amidase comprised approximately 20-25% of the total cell protein in each case, and these values were confirmed following purification of the enzyme from each of the different strains. The hyperactivity of strain MM6 was due predominantly to the production of more wild-type enzyme, whilst in strain MM8 it was due to production of approximately the same amount of enzyme, but with a substantially enhanced Kcat. The low amidase activity of strain MM15 was due to its increased thermolability since approximately four-fifths of the enzyme was present as inactive monomers and dimers. Growth of strain MM15 at lower temperatures was found to have a profound effect upon the subsequent Kcat of the enzyme. The conditions under which switch-off occurs have been investigated, and amidase was purified in its switched-off form and compared for the presence of modifying groups in parallel with purified active amidase. A protein involved in the reactivation of inactive amidase was isolated and purified, and the physico-chemical properties of both inactive amidase and the activation protein have been investigated.

Published
1990

8. Francisella Tularensis: Tularemia

Author

Johansson, Anders, primary, Tomaso, Herbert, additional, Padeshki, Plamen, additional, Sjöstedt, Anders, additional, Silman, Nigel, additional, and Pilo, Paola, additional

Published
2012
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12. An immunological approach to detect phosphate stress in populations and single cells of photosynthetic picoplankton

Author

Scanlan, David J., Silman, Nigel J., Donald, Kirsten M., Wilson, William H., Carr, Noel G., Joint, Ian, and Mann, Nicholas H.

Subjects
Marine plankton -- Research, Bacteria, Photosynthetic -- Research, Biological sciences
Abstract

The cell wall-associated phosphate-binding protein in the marine cyanobacterium Synechococcus sp. strain WH7803 was evaluated for application as a diagnostic marker for the P status of photosynthetic picoplankton. The protein was found to be induced at concentrations of P(sub i) typical of oligotrophic conditions. PstS expression can be specifically determined by standard Western blotting procedures in natural mesocosm samples under conditions in which the N/P ratio was artificially manipulated to force P depletion.

Published
1997

13. ADP-ribosylation of glutamine synthetase in the cyanobacterium Synechocystis sp. strain PCC 6803

Author

Silman, Nigel J., Carr, Noel G., and Mann, Nicholas H.

Subjects
Cyanobacteria -- Research, Amino acid metabolism -- Research, Biological sciences
Abstract

A study has been conducted to examine the regulation of glutamine synthetase (GS) activity in the cyanobacteria Synechocystis sp. strain PCC 6803. Dialysis of the supernatant from cell extracts added with ammonium ions and glutamine showed loss of inactivation activity. However, this was restored upon the addition of energy sources such as NADH, NADPH, NADP+ or NAD+. This indicates that GS inactivation in Synechocystis sp. strain PCC 6803 is regulated by ADP-ribosylation.

Published
1995

15. Tailoring the electrochemical properties of carbon nanotube modified indium tin oxide via in situ grafting of aryl diazonium

Author

Wong, Zhi Yi, Scurr, David J., Silman, Nigel, Jackson, Simon K., Mendes, Paula M., Aylott, Jonathan W., Rawson, Frankie J., and Hicks, Jacqueline

Abstract

Our ability to tailor the electronic properties of surfaces by nanomodification is paramount for various applications, including development of sensing, fuel cell, and solar technologies. Moreover, in order to improve the rational design of conducting surfaces, an improved understanding of structure/function relationships of nanomodifications and effect they have on the underlying electronic properties is required. Herein, we report on the tuning and optimization of the electrochemical properties of indium tin oxide (ITO) functionalized with single-walled carbon nanotubes (SWCNTs). This was achieved by controlling in situ grafting of aryl amine diazonium films on the nanoscale which were used to covalently tether SWCNTs. The structure/function relationship of these nanomodifications on the electronic properties of ITO was elucidated via time-of-flight secondary ion mass spectrometry and electrochemical and physical characterization techniques which has led to new mechanistic insights into the in situ grafting of diazonium. We discovered that the connecting bond is a nitro group which is covalently linked to a carbon on the aryl amine. The increased understanding of the surface chemistry gained through these studies enabled us to fabricate surfaces with optimized electron transfer kinetics. The knowledge gained from these studies allows for the rational design and tuning of the electronic properties of ITO-based conducting surfaces important for development of various electronic applications.

Published
2017

16. Development and Assessment of a Diagnostic DNA Oligonucleotide Microarray for Detection and Typing of Meningitis-Associated Bacterial Species

Author

Bannister, Stephanie, primary, Kidd, Stephen, additional, Kirby, Elizabeth, additional, Shah, Sonal, additional, Thomas, Anvy, additional, Vipond, Richard, additional, Elmore, Michael, additional, Telfer Brunton, Andrew, additional, Marsh, Peter, additional, Green, Steve, additional, Silman, Nigel, additional, and Kempsell, Karen, additional

Published
2018
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20. A black necrotic ulcer. (Case report)

Author

Lawn, Stephen D, Planche, Timothy, Riley, Peter, Holwill, Stephen, Silman, Nigel, Bewley, Kevin, Rice, Philip, and Wansbrough-Jones, Mark H

Subjects
Skin -- Ulcers, Cowpox
Published
2003

21. Correction: Temporal Expression of Peripheral Blood Leukocyte Biomarkers in a Macaca fascicularis Infection Model of Tuberculosis; Comparison with Human Datasets and Analysis with Parametric/Non-parametric Tools for Improved Diagnostic Biomarker Identification

Author

Javed, Sajid, primary, Marsay, Leanne, additional, Wareham, Alice, additional, Lewandowski, Kuiama S., additional, Williams, Ann, additional, Dennis, Michael J., additional, Sharpe, Sally, additional, Vipond, Richard, additional, Silman, Nigel, additional, Ball, Graham, additional, and Kempsell, Karen E., additional

Published
2016
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22. Influenza A Virus Challenge Models in Cynomolgus Macaques Using the Authentic Inhaled Aerosol and Intra-Nasal Routes of Infection

Author

Marriott, Anthony C., primary, Dennis, Mike, additional, Kane, Jennifer A., additional, Gooch, Karen E., additional, Hatch, Graham, additional, Sharpe, Sally, additional, Prevosto, Claudia, additional, Leeming, Gail, additional, Zekeng, Elsa-Gayle, additional, Staples, Karl J., additional, Hall, Graham, additional, Ryan, Kathryn A., additional, Bate, Simon, additional, Moyo, Nathifa, additional, Whittaker, Catherine J., additional, Hallis, Bassam, additional, Silman, Nigel J., additional, Lalvani, Ajit, additional, Wilkinson, Tom M., additional, Hiscox, Julian A., additional, Stewart, James P., additional, and Carroll, Miles W., additional

Published
2016
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23. Temporal Expression of Peripheral Blood Leukocyte Biomarkers in a Macaca fascicularis Infection Model of Tuberculosis; Comparison with Human Datasets and Analysis with Parametric/Non-parametric Tools for Improved Diagnostic Biomarker Identification

Author

Javed, Sajid, primary, Marsay, Leanne, additional, Wareham, Alice, additional, Lewandowski, Kuiama S., additional, Williams, Ann, additional, Dennis, Michael J., additional, Sharpe, Sally, additional, Vipond, Richard, additional, Silman, Nigel, additional, Ball, Graham, additional, and Kempsell, Karen E., additional

Published
2016
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26. Whole-genome sequencing investigation of animal-skin-drum-associated UK anthrax cases reveals evidence of mixed populations and relatedness to a US case

Author

Pullan, Steven T., primary, Pearson, Talima R., additional, Latham, Jennie, additional, Mason, Joanne, additional, Atkinson, Barry, additional, Silman, Nigel J., additional, Marston, Chung K., additional, Sahl, Jason W., additional, Birdsell, Dawn, additional, Hoffmaster, Alex R., additional, Keim, Paul, additional, and Vipond, Richard, additional

Published
2015
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28. Low Dose Influenza Virus Challenge in the Ferret Leads to Increased Virus Shedding and Greater Sensitivity to Oseltamivir

Author

Marriott, Anthony C., primary, Dove, Brian K., additional, Whittaker, Catherine J., additional, Bruce, Christine, additional, Ryan, Kathryn A., additional, Bean, Thomas J., additional, Rayner, Emma, additional, Pearson, Geoff, additional, Taylor, Irene, additional, Dowall, Stuart, additional, Plank, Jenna, additional, Newman, Edmund, additional, Barclay, Wendy S., additional, Dimmock, Nigel J., additional, Easton, Andrew J., additional, Hallis, Bassam, additional, Silman, Nigel J., additional, and Carroll, Miles W., additional

Published
2014
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29. Francisella tularensis : Tularemia

Author

Johansson, Anders, Tomaso, Herbert, Padeshki, Plamen, Sjöstedt, Anders, Silman, Nigel, Pilo, Paola, Johansson, Anders, Tomaso, Herbert, Padeshki, Plamen, Sjöstedt, Anders, Silman, Nigel, and Pilo, Paola

Abstract

This practical guide gives some starting points to manage biological safety issues with Francisella tularensis.

Published
2012
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33. Genome Sequencing Shows that European Isolates of Francisella tularensis Subspecies tularensis Are Almost Identical to US Laboratory Strain Schu S4

Author

Chaudhuri, Roy R., primary, Ren, Chuan-Peng, additional, Desmond, Leah, additional, A. Vincent, Gemma, additional, Silman, Nigel J., additional, Brehm, John K., additional, Elmore, Michael J., additional, Hudson, Michael J., additional, Forsman, Mats, additional, Isherwood, Karen E., additional, Guryčová, Darina, additional, Minton, Nigel P., additional, Titball, Richard W., additional, Pallen, Mark J., additional, and Vipond, Richard, additional

Published
2007
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36. ADP-ribosylation of glutamine synthetase in the cyanobacterium Synechocytis sp.strainPCC 6803.

Author

Silman, Nigel J. and Carr, Noel G.

Subjects
*GLUTAMINE synthetase, *CYANOBACTERIA biotechnology
Abstract

Discusses the glutamine synthetase (GS) inactivation as observed in crude cell extracts and in the high-speed supernatant fraction from the cyanobacterium Synechocytosis sp. strain PCC 6803 following the addition of ammonium ions, glutamine or glutamate. Inactivation of GS involves ADP-ribosylation.

Published
1995
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37. Tailoring the electrochemical properties of carbon nanotube modified indium tin oxide via in situ grafting of aryl diazonium

Author

Hicks, Jacqueline, Wong, Zhi Yi, Scurr, David J., Silman, Nigel, Jackson, Simon K., Mendes, Paula M., Aylott, Jonathan W., Rawson, Frankie J., Hicks, Jacqueline, Wong, Zhi Yi, Scurr, David J., Silman, Nigel, Jackson, Simon K., Mendes, Paula M., Aylott, Jonathan W., and Rawson, Frankie J.

Abstract

Our ability to tailor the electronic properties of surfaces by nanomodification is paramount for various applications, including development of sensing, fuel cell, and solar technologies. Moreover, in order to improve the rational design of conducting surfaces, an improved understanding of structure/function relationships of nanomodifications and effect they have on the underlying electronic properties is required. Herein, we report on the tuning and optimization of the electrochemical properties of indium tin oxide (ITO) functionalized with single-walled carbon nanotubes (SWCNTs). This was achieved by controlling in situ grafting of aryl amine diazonium films on the nanoscale which were used to covalently tether SWCNTs. The structure/function relationship of these nanomodifications on the electronic properties of ITO was elucidated via time-of-flight secondary ion mass spectrometry and electrochemical and physical characterization techniques which has led to new mechanistic insights into the in situ grafting of diazonium. We discovered that the connecting bond is a nitro group which is covalently linked to a carbon on the aryl amine. The increased understanding of the surface chemistry gained through these studies enabled us to fabricate surfaces with optimized electron transfer kinetics. The knowledge gained from these studies allows for the rational design and tuning of the electronic properties of ITO-based conducting surfaces important for development of various electronic applications.

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38. Electrochemical communication with the inside of cells using micro-patterned vertical carbon nanofibre electrodes

Author

Rawson, Frankie J., Cole, M.T, Hicks, Jacqueline, Aylott, Jonathan W., Milne, W.I., Collins, C.M., Jackson, Simon K., Silman, Nigel, Mendes, Paula M., Rawson, Frankie J., Cole, M.T, Hicks, Jacqueline, Aylott, Jonathan W., Milne, W.I., Collins, C.M., Jackson, Simon K., Silman, Nigel, and Mendes, Paula M.

Abstract

With the rapidly increasing demands for ultrasensitive biodetection, the design and applications of new nano-scale materials for development of sensors based on optical and electrochemical transducers have attracted substantial interest. In particular, given the comparable sizes of nanomaterials and biomolecules, there exist plenty of opportunities to develop functional nanoprobes with biomolecules for highly sensitive and selective biosensing, shedding new light on cellular behaviour. Towards this aim, herein we interface cells with patterned nano-arrays of carbon nanofibers forming a nanosensor-cell construct. We show that such a construct is capable of electrochemically communicating with the intracellular environment.

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