A5076056796- Bacterial Genetics and Biotechnology
- Aquaculture disease management and microbiota
- Plant Pathogens and Resistance
- Amino Acid Enzymes and Metabolism
- Ion channel regulation and function
- Photosynthetic Processes and Mechanisms
- Plant Pathogens and Fungal Diseases
- Genetics, Aging, and Longevity in Model Organisms
- Myxozoan Parasites in Aquatic Species
- Ion Transport and Channel Regulation
- Spectroscopy and Quantum Chemical Studies
- Mitochondrial Function and Pathology
- Drug Transport and Resistance Mechanisms
- Yeasts and Rust Fungi Studies
- Sulfur Compounds in Biology
- Parasite Biology and Host Interactions
- Glutathione Transferases and Polymorphisms
- Spaceflight effects on biology
- Invertebrate Immune Response Mechanisms
- Advanced Glycation End Products research
- Carcinogens and Genotoxicity Assessment
- Aluminum toxicity and tolerance in plants and animals
- Enzyme function and inhibition
- Plant tissue culture and regeneration
- Gut microbiota and health
University of Aberdeen
2012-2024
Institute of Medical Sciences
2002-2015
University of Chicago
1990-2004
Institute of Medical Biology
1998
University of East Anglia
1984-1991
Stanford University
1989-1990
The mechanism by which methionine relieves the growth inhibition of Escherichia coli K-12 that is caused organic weak acid food preservatives was investigated. In presence 8 mM acetate specific rate E. Frag1 (in MacIlvaine's minimal medium pH 6·0) reduced 50%. Addition restores to 80% observed in untreated controls. Similar relief seen with cultures treated either benzoate or propionate. Mutants an elevated intracellular pool were almost completely resistant inhibitory effects acetate,...
ABSTRACT During inhibition of cell growth by weak acids, there is substantial accumulation the acid anions in cytoplasm. This study was undertaken to determine impact anion on cellular pools. At pH 6, presence 8 mM acetate led an internal pool greater than 240 and resulted reduced levels glutamate cell, but were no significant changes K + Na levels. low osmolarity, change compensated for only a small fraction accumulated anion. However, at high over half acetate. Recovery normal cytoplasmic...
Escherichia coli responds to an increase in medium osmolarity by accumulating K+ and glutamate. At low a large fraction of cytoplasmic serves balance charge on macromolecular anions. That is here referred as bound, distinguished from free that small higher where increases markedly, the bound decreases but absolute amount expressed per unit dry weight increases. The can be explained largely reduction putrescine at high osmolarity. osmolarity, glutamate major anion, equal least 70% K+. A...
Escherichia coli possesses two glutathione‐gated potassium channels, KefB and KefC, that are activated by glutathione‐S‐conjugates formed with methylglyoxal. We demonstrate activation of the channels leads to cytoplasmic acidification this protects cells during electrophilic attack. Further, we mutants lacking can be protected against lethal effects methylglyoxal cytoplasm a weak acid. The degree protection is determined absolute value pH i time at which takes place. Alterations in do not...
Summary In bacteria the detoxification of compounds as diverse methylglyoxal and chlorodinitrobenzene proceeds through formation a glutathione adduct. Gram‐negative bacteria, e.g. Escherichia coli , such adducts activate one, or both, pair potassium efflux systems KefB KefC. These share many properties cation‐translocating channels in eukaryotes. The activity these has been found to be present range but not glutathione‐deficient species Gram‐positive organisms. conservation organisms...
Accumulation of K+ ions and glutamate plays a primary role in maintaining osmotic balance Escherichia coli, as illustrated by the high concentrations these present cells growing medium osmolality. We found that two gamma-glutamyl peptides glutamine also accumulated during growth at osmolarity. In mutant unable to make trehalose 1.3 osM medium, glutathione, gamma-glutamylglutamine, levels 73, 33, 140 mumol/g protein, respectively. such cells, was 1,450 indicating glutathione...
Summary Mechanosensitive channels play an essential role in the regulation of turgor pressure bacteria. In Escherichia coli , there are multiple mechanosensitive that have been characterized genetically: MscL, YggB and KefA. this report, we describe cloning kefA gene, organization KefA protein phenotype a missense mutation, which affects channel. The altered function channel is manifest through increased sensitivity to K + during growth at low osmolarity complete inhibition media containing...
The role of the KefB and KefC potassium efflux systems in protecting Escherichia coli cells against toxic effects electrophile N-ethylmaleimide has been investigated. Activation aids survival exposed to high concentrations (> 100 microM) NEM. High reduce protection afforded by activation KefC, but possession these is still important under conditions. Kdp system, which confers sensitivity methylglyoxal, did not affect Survival correlated with reduction cytoplasmic pH upon channels. In...
The Kdp K + uptake system of Escherichia coli is induced by limitation for and/or high osmolarity. In the present study, regulation activity has been investigated in E. mutants possessing only as mechanism accumulation. Cells grown presence low (0.1–1 mM) exhibit normal growth. However, growth inhibition results from exposure cells to moderate levels external (> 5 mM). Measurement cytoplasmic pH, pools and transport via demonstrates that rapidly irreversibly inhibited . Concentrations...
Regulation of the cytoplasmic pH Exiguobacterium aurantiacum is dependent on presence Na + in medium. The data suggest that above 500 μM external cells are able to regulate by operation a cycle involving /H antiport and route for rapid entry. Our indicate rate entry subject control via feedback inhibition.
A transgenic strain of the model nematode Caenorhabditis elegans in which bioluminescence reports on relative, whole-organism ATP levels was used to test an environmentally-relevant mixture pollutants extracted from processed sewage sludge. Changes bioluminescence, following exposure sludge extract, were assess relative and overall metabolic health. Reproductive function longevity also monitored. short (up 8 h) sublethal L4 larval stage worms extract had a concentration-dependent,...
Mutants of Escherichia coli lacking all the known saturable K+ transport systems, "triple mutants," require elevated concentrations for growth. activity in such mutants, called TrkF activity, has low substrate specificity and a rate that increases with increasing external pH. Attempts to isolate mutants requiring even higher failed, implying either is essential or composed multiple minor activities. Instead, we sought mutations allowed triple grow at lower concentrations. Mutations so...
Sublethal metabolic effects are informative toxicological end points. We used a rapid quantitative point, bioluminescence of firefly luciferase expressing Caenorhabditis elegans, to assess sublethal chronic exposure (19 h) the oxidative stress agent and environmental pollutant cadmium (provided as chloride salt). Bioluminescence declined in concentration-dependent manner concentration range tested (0-30 microM Cd), with comparable sensitivity reproduction developmental assay points (after 67...
Escherichia coli accumulated taurine at high osmolarity via the ProU and ProP transport systems. Taurine accumulation was shown to be osmotically active as it displaced cytoplasmic K+. In contrast betaine proline, only modestly enhanced growth rate of E. if cell unable synthesise trehalose. These studies show that cannot used a tracer for extra-cytoplasmic space bacteria grown osmolarity.
The multicellular model organism Caenorhabditis elegans is a small nematode of approximately 1 mm in size adulthood that genetically and experimentally tractable. It economical easy to culture dispense liquid medium which makes it well suited for medium-throughput screening. We have previously validated the use transgenic luciferase expressing C. strains provide rapid vivo assessment nematode's ATP levels.1-3 Here we present required materials procedure carry out bioassays with...
Saprolegniosis is a major destructive disease in freshwater aquaculture. The economic impact of saprolegniosis on aquaculture necessitates further study the range
Abstract Background Haplosclerid marine sponges produce pore forming polyalkylpyridinium salts (poly-APS), which can be used to deliver macromolecules into cells. The aim of this study was investigate the delivery DNA, siRNA and lucifer yellow cells mediated by poly-APS its potential mechanisms as compared with other lipofection systems (lipofectamine N 4 , 9 -dioleoylspermine (LipoGen)). DNA condensation evaluated HEK 293 HtTA HeLa were formation intracellular cDNA, yellow. Results Poly-APS...
Here we describe the first application of transient gene silencing in Saprolegnia parasitica, a pathogenic oomycete that infects wide range fish, amphibians, and crustaceans. A encoding putative tyrosinase from S. SpTyr, was selected to investigate suitability RNA-interference (RNAi) functionally characterize genes this economically important pathogen. Tyrosinase is mono-oxygenase enzyme catalyses O-hydroxylation monophenols subsequent oxidation O-diphenols quinines. These enzymes are widely...
The protonophore-mediated collapse of the large delta pH that acidophiles maintain across their cytoplasmic membranes was augmented by presence Cl-, and Cl- influx into cells occurred evidently in response to protonophore-induced increase inside-positive membrane potential (+ psi). In respiring cells, addition but not SO4(2-) salts caused a rapid precipitous decrease + psi. A Nernstian relationship between imposed transmembrane K+ gradient valinomycin-induced diffusion potentials observed...