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19 results on '"O'Donovan, Lisa A"'

1. In planta ectopic expression of two subtypes of tomato cellulose synthase-like M genes affects cell wall integrity and supports a role in arabinogalactan and/or rhamnogalacturonan-I biosynthesis.

Author

Hassan, Ali S, O'Donovan, Lisa A, Cowley, James M, Akomeah, Belinda, Phillips, Renee J, Pettolino, Filomena, Schultz, Carolyn J, and Burton, Rachel A

Subjects
*PLANT cell walls, *TRITERPENOID saponins, *GLUCANS, *GENE families, *TOMATOES, *CELLULOSE synthase, *NICOTIANA benthamiana
Abstract

Diversification of the cellulose synthase superfamily of glycosyltransferases has provided plants with the ability to synthesize varied cell wall polysaccharides such as xyloglucan, mannans, and the mixed-linkage glucans of cereals. Surprisingly, some but not all members of the cellulose synthase-like M (CslM) gene family have recently been shown to be involved in the glycosylation of the aglycone core of a range of triterpenoid saponins. However, no cell wall activity has yet been attributed to any of the CslM gene family members. Here, evolution of the CslM gene family in eudicots is explored to better understand the differences between the two metabolically distinct classes of CslMs (CslM1 and CslM2) and the very closely related CslGs. To achieve this, a robust tBLASTn approach was developed to identify CslM1, CslM2, and CslG sequences using diagnostic peptides, suitable for complex genomes using unannotated and short-read datasets. To ascertain whether both CslM1 and CslM2 proteins have cell wall functions, in addition to the 'saponin' role of CslM2, tomato CslM1 and CslM2 genes were ectopically expressed in Arabidopsis thaliana by stable transformation and in the transient Nicotiana benthamiana system. Transformed plants were analysed with immunofluorescence, immunogold transmission electron microscopy, and cell wall polysaccharides were extracted for monosaccharide linkage analysis. Our results support a role for both CslM1 and CslM2 in the biosynthesis of type II arabinogalactan linkages, generating new insight into how the diverse functions of CslMs can coexist and providing clear targets for future research. [ABSTRACT FROM AUTHOR]

Published
2025
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7. Lateral flagella and swarming motility in Aeromonas species

Author

Kirov, Sylvia M., Tassell, Bronwen C., Semmler, Annalese B.T., O'Donovan, Lisa A., Rabaan, Ali A., and Shaw, Jonathan G.

Subjects
Bacteria -- Motility, Flagella (Microbiology) -- Physiological aspects, Bacterial infections -- Physiological aspects, Biological sciences
Abstract

Research reveals that at least 50% of the Aeromonas species produce lateral flagella involved in the swarming motility of the bacteria. Data indicate that the flagella protein is coded by the laf gene and mutation in this gene inactivates the motility.

Published
2002

9. In vitro Activity of Robenidine Analog NCL195 in Combination With Outer Membrane Permeabilizers Against Gram-Negative Bacterial Pathogens and Impact on Systemic Gram-Positive Bacterial Infection in Mice

Author

Pi, Hongfei, primary, Nguyen, Hang Thi, additional, Venter, Henrietta, additional, Boileau, Alexandra R., additional, Woolford, Lucy, additional, Garg, Sanjay, additional, Page, Stephen W., additional, Russell, Cecilia C., additional, Baker, Jennifer R., additional, McCluskey, Adam, additional, O’Donovan, Lisa A., additional, Trott, Darren J., additional, and Ogunniyi, Abiodun D., additional

Published
2020
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15. Genetics and physiology of cell wall polysaccharides in the model C4 grass, Setaria viridis spp.

Author

Ermawar, Riksfardini A., Collins, Helen M., Byrt, Caitlin S., Henderson, Marilyn, O'Donovan, Lisa A., Shirley, Neil J., Schwerdt, Julian G., Lahnstein, Jelle, Fincher, Geoffrey B., and Burton, Rachel A.

Subjects
POLYSACCHARIDES, CELLULOSE synthase, PLANT cell walls, SORGHUM, BRACHYPODIUM, BIOINFORMATICS
Abstract

Background: Setaria viridis has emerged as a model species for the larger C4 grasses. Here the cellulose synthase (CesA) superfamily has been defined, with an emphasis on the amounts and distribution of (1,3;1,4)-β-glucan, a cell wall polysaccharide that is characteristic of the grasses and is of considerable value for human health. Methods: Orthologous relationship of the CesA and Poales-specific cellulose synthase-like (Csl) genes among Setaria italica (Si), Sorghum bicolor (Sb), Oryza sativa (Os), Brachypodium distachyon (Bradi) and Hordeum vulgare (Hv) were compared using bioinformatics analysis. Transcription profiling of Csl gene families, which are involved in (1,3;1,4)-β-glucan synthesis, was performed using real-time quantitative PCR (Q-PCR). The amount of (1,3;1,4)-β-glucan was measured using a modified Megazyme assay. The fine structures of the (1,3;1,4)-β-glucan, as denoted by the ratio of cellotriosyl to cellotetraosyl residues (DP3:DP4 ratio) was assessed by chromatography (HPLC and HPAEC-PAD). The distribution and deposition of the MLG was examined using the specific antibody BG-1 and captured using fluorescence and transmission electron microscopy (TEM). Results: The cellulose synthase gene superfamily contains 13 CesA and 35 Csl genes in Setaria. Transcript profiling of CslF, CslH and CslJ gene families across a vegetative tissue series indicated that SvCslF6 transcripts were the most abundant relative to all other Csl transcripts. The amounts of (1,3;1,4)-β-glucan in Setaria vegetative tissues ranged from 0.2% to 2.9% w/w with much smaller amounts in developing grain (0.003% to 0.013% w/w). In general, the amount of (1,3;1,4)-β-glucan was greater in younger than in older tissues. The DP3:DP4 ratios varied between tissue types and across developmental stages, and ranged from 2.4 to 3.0:1. The DP3:DP4 ratios in developing grain ranged from 2.5 to 2.8:1. Micrographs revealing the distribution of (1,3;1,4)-β-glucan in walls of different cell types and the data were consistent with the quantitative (1,3;1,4)-β-glucan assays. Conclusion: The characteristics of the cellulose synthase gene superfamily and the accumulation and distribution of (1,3;1,4)-β-glucans in Setaria are similar to those in other C4 grasses, including sorghum. This suggests that Setaria is a suitable model plant for cell wall polysaccharide biology in C4 grasses. [ABSTRACT FROM AUTHOR]

Published
2015
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17. Comparison of Two Transmission Electron Microscopy Methods to Visualize Drug-Induced Alterations of Gram-Negative Bacterial Morphology

Author

Cecilia C. Russell, Abiodun D. Ogunniyi, Hang Thi Nguyen, Henrietta Venter, Darren J. Trott, Adam McCluskey, Stephen W. Page, Lisa A. O’Donovan, Nguyen, Hang Thi, O'donovan, Lisa A, Venter, Henrietta, Russell, Cecilia C, McCluskey, Adam, Page, Stephen W, Trott, Darren J, and Ogunniyi, Abiodun D

Subjects
0301 basic medicine, Microbiology (medical), Gram-negative bacteria, 030106 microbiology, macromolecular substances, Biochemistry, Microbiology, Article, Bacterial cell structure, 03 medical and health sciences, chemistry.chemical_compound, transmission electron microscopy, medicine, Pharmacology (medical), colistin, General Pharmacology, Toxicology and Pharmaceutics, drug interaction, biology, lcsh:RM1-950, tokuyasu cryo-ultramicrotomy, Tokuyasu cryo-ultramicrotomy, biology.organism_classification, gram-negative bacteria, lcsh:Therapeutics. Pharmacology, 030104 developmental biology, Infectious Diseases, Membrane, chemistry, Transmission electron microscopy, Colistin, Ultrastructure, Biophysics, bacterial membrane, Peptidoglycan, Bacterial cellular morphologies, medicine.drug, bacterial cell wall
Abstract

In this study, we optimized and compared different transmission electron microscopy (TEM) methods to visualize changes to Gram-negative bacterial morphology induced by treatment with a robenidine analogue (NCL195) and colistin combination. Aldehyde-fixed bacterial cells (untreated, treated with colistin or NCL195 + colistin) were prepared using conventional TEM methods and compared with ultrathin Tokuyasu cryo-sections. The results of this study indicate superiority of ultrathin cryo-sections in visualizing the membrane ultrastructure of Escherichia coli and Pseudomonas aeruginosa, with a clear delineation of the outer and inner membrane as well as the peptidoglycan layer. We suggest that the use of ultrathin cryo-sectioning can be used to better visualize and understand drug interaction mechanisms on the bacterial cell membrane. Refereed/Peer-reviewed

Published
2021
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18. In vitro synergistic activity of NCL195 in combination with colistin against Gram-negative bacterial pathogens

Author

Stephen W. Page, Adam McCluskey, Abiodun D. Ogunniyi, Tania Veltman, Hang Thi Nguyen, Darren J. Trott, Henrietta Venter, Cecilia C. Russell, Lisa A. O’Donovan, Ruth Williams, Nguyen, Hang Thi, Venter, Henrietta, Veltman, Tania, Williams, Ruth, O'Donovan, Lisa Anne, Russell, Cecilia C, McCluskey, Adam, Page, Stephen W, Ogunniyi, Abiodun David, and Trott, Darren J

Subjects
0301 basic medicine, Microbiology (medical), Male, Gram-negative bacteria, Robenidine, Klebsiella pneumoniae, medicine.drug_class, 030106 microbiology, Antibiotics, synergy, Microbial Sensitivity Tests, medicine.disease_cause, Microbiology, 03 medical and health sciences, Mice, 0302 clinical medicine, multidrug resistance, Drug Resistance, Multiple, Bacterial, Gram-Negative Bacteria, transmission electron microscopy, medicine, Animals, Humans, Pharmacology (medical), 030212 general & internal medicine, colistin, biology, Dose-Response Relationship, Drug, Pseudomonas aeruginosa, Chemistry, Colistin, Drug Synergism, General Medicine, Hep G2 Cells, biology.organism_classification, Antimicrobial, gram-negative bacteria, Acinetobacter baumannii, Anti-Bacterial Agents, Multiple drug resistance, Infectious Diseases, HEK293 Cells, Models, Animal, Drug Therapy, Combination, NCL195, Gram-Negative Bacterial Infections, medicine.drug
Abstract

In this study, the potential of using the novel antibiotic NCL195 combined with subinhibitory concentrations of colistin against infections caused by Gram-negative bacteria (GNB) was investigated. We showed synergistic activity of the combination NCL195 + colistin against clinical multidrug-resistant GNB pathogens with minimum inhibitory concentrations (MICs) for NCL195 ranging from 0.5–4 μg/mL for Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa, whereas NCL195 alone had no activity. Transmission electron microscopy of the membrane morphology of E. coli and P. aeruginosa after single colistin or combination drug treatment showed marked ultrastructural changes most frequently in the cell envelope. Exposure to NCL195 alone did not show any change compared with untreated control cells, whereas treatment with the NCL195 + colistin combination caused more damage than colistin alone. Direct evidence for this interaction was demonstrated by fluorescence-based membrane potential measurements. We conclude that the synergistic antimicrobial activity of the combination NCL195 + colistin against GNB pathogens warrants further exploration for specific treatment of acute GNB infections. Refereed/Peer-reviewed

Published
2021

19. In vitro Activity of Robenidine Analog NCL195 in Combination With Outer Membrane Permeabilizers Against Gram-Negative Bacterial Pathogens and Impact on Systemic Gram-Positive Bacterial Infection in Mice

Author

Abiodun D. Ogunniyi, Darren J. Trott, Lisa A. O’Donovan, Henrietta Venter, Jennifer R. Baker, Lucy Woolford, Stephen W. Page, Cecilia C. Russell, Hongfei Pi, Hang Thi Nguyen, Adam McCluskey, Alexandra R Boileau, Sanjay Garg, Pi, Hongfei, Nguyen, Hang Thi, Venter, Henrietta, Boileau, Alexandra R, Woolford, Lucy, Garg, Sanjay, Page, Stephen W, Russell, Cecilia C, Baker, Jennifer R, McCluskey, Adam, O'Donovan, Lisa A, Trott, Darren J, and Ogunniyi, Abiodun D

Subjects
Microbiology (medical), bacterial sepsis, lcsh:QR1-502, medicine.disease_cause, Microbiology, Enterococcus faecalis, lcsh:Microbiology, 03 medical and health sciences, multidrug resistance, transmission electron microscopy, medicine, cryo-ultramicrotomy, 030304 developmental biology, Original Research, 0303 health sciences, biology, 030306 microbiology, Pseudomonas aeruginosa, Chemistry, polymyxin B, Enterobacter, biology.organism_classification, Antimicrobial, bioluminescence, Acinetobacter baumannii, Multiple drug resistance, Staphylococcus aureus, membrane potential, NCL195, Polymyxin B, medicine.drug
Abstract

usc Multidrug-resistant (MDR) pathogens, particularly the ESKAPE group (Enterococcus faecalis/faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Escherichia coli, and Enterobacter spp.), have become a public health threat worldwide. Development of new antimicrobial classes and the use of drugs in combination are potential strategies to treat MDR ESKAPE pathogen infections and promote optimal antimicrobial stewardship. Here, the in vitro antimicrobial activity of robenidine analog NCL195 alone or in combination with different concentrations of three outer membrane permeabilizers [ethylenediaminetetraacetic acid (EDTA), polymyxin B nonapeptide (PMBN), and polymyxin B (PMB)] was further evaluated against clinical isolates and reference strains of key Gram-negative bacteria. NCL195 alone was bactericidal against Neisseria meningitidis and Neisseria gonorrhoeae (MIC/MBC = 32 μg/mL) and demonstrated synergistic activity against P. aeruginosa, E. coli, K. pneumoniae, and Enterobacter spp. strains in the presence of subinhibitory concentrations of EDTA, PMBN, or PMB. The additive and/or synergistic effects of NCL195 in combination with EDTA, PMBN, or PMB are promising developments for a new chemical class scaffold to treat Gram-negative infections. Tokuyasu cryo ultramicrotomy was used to visualize the effect of NCL195 on bioluminescent S. aureus membrane morphology. Additionally, NCL195’s favorable pharmacokinetic and pharmacodynamic profile was further explored in in vivo safety studies in mice and preliminary efficacy studies against Gram-positive bacteria. Mice administered two doses of NCL195 (50 mg/kg) by the intraperitoneal (IP) route 4 h apart showed no adverse clinical effects and no observable histological effects in major organs. In bioluminescent Streptococcus pneumoniae and S. aureus murine sepsis challenge models, mice that received two 50 mg/kg doses of NCL195 4 or 6 h apart exhibited significantly reduced bacterial loads and longer survival times than untreated mice. However, further medicinal chemistry and pharmaceutical development to improve potency, solubility, and selectivity is required before efficacy testing in Gram-negative infection models. Refereed/Peer-reviewed

Published
2020

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