Biomaterial Database

Voltage clamp effects on bacterial chemotaxis. 1984

Y Margolin, and M Eisenbach

To examine whether or not sensory signaling in bacteria is by way of fluctuations in membrane potential, we studied the effect of clamping the potential on bacterial chemotaxis. The potential was clamped by valinomycin, a K+ -specific ionophore, in the presence of K+. Despite the clamped potential, sensory signaling did occur: both Escherichia coli and Bacillus subtilis cells were still excitable and adaptable under these conditions. It is concluded that signaling in the excitation and adaptation steps of chemotaxis is not by way of fluctuations in the membrane potential.

UI	MeSH Term	Description	Entries
D008564	Membrane Potentials	The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).	Resting Potentials,Transmembrane Potentials,Delta Psi,Resting Membrane Potential,Transmembrane Electrical Potential Difference,Transmembrane Potential Difference,Difference, Transmembrane Potential,Differences, Transmembrane Potential,Membrane Potential,Membrane Potential, Resting,Membrane Potentials, Resting,Potential Difference, Transmembrane,Potential Differences, Transmembrane,Potential, Membrane,Potential, Resting,Potential, Transmembrane,Potentials, Membrane,Potentials, Resting,Potentials, Transmembrane,Resting Membrane Potentials,Resting Potential,Transmembrane Potential,Transmembrane Potential Differences
D009550	Nigericin	A polyether antibiotic which affects ion transport and ATPase activity in mitochondria. It is produced by Streptomyces hygroscopicus. (From Merck Index, 11th ed)	Epinigericin,Pandavir
D002250	Carbon Radioisotopes	Unstable isotopes of carbon that decay or disintegrate emitting radiation. C atoms with atomic weights 10, 11, and 14-16 are radioactive carbon isotopes.	Radioisotopes, Carbon
D002633	Chemotaxis	The movement of cells or organisms toward or away from a substance in response to its concentration gradient.	Haptotaxis
D004926	Escherichia coli	A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.	Alkalescens-Dispar Group,Bacillus coli,Bacterium coli,Bacterium coli commune,Diffusely Adherent Escherichia coli,E coli,EAggEC,Enteroaggregative Escherichia coli,Enterococcus coli,Diffusely Adherent E. coli,Enteroaggregative E. coli,Enteroinvasive E. coli,Enteroinvasive Escherichia coli
D001412	Bacillus subtilis	A species of gram-positive bacteria that is a common soil and water saprophyte.	Natto Bacteria,Bacillus subtilis (natto),Bacillus subtilis subsp. natto,Bacillus subtilis var. natto
D014316	Tritium	The radioactive isotope of hydrogen also known as hydrogen-3. It contains two NEUTRONS and one PROTON in its nucleus and decays to produce low energy BETA PARTICLES.	Hydrogen-3,Hydrogen 3
D014634	Valinomycin	A cyclododecadepsipeptide ionophore antibiotic produced by Streptomyces fulvissimus and related to the enniatins. It is composed of 3 moles each of L-valine, D-alpha-hydroxyisovaleric acid, D-valine, and L-lactic acid linked alternately to form a 36-membered ring. (From Merck Index, 11th ed) Valinomycin is a potassium selective ionophore and is commonly used as a tool in biochemical studies.