Mechanisms of volume regulation in Mycoplasma gallisepticum

Thesis/Dissertation · Thu Jan 01 00:00:00 EST 1987

OSTI ID:6409448

Linker, C S

Mycoplasma gallisepticum, a cell wall-less bacterium, must confront the problem of colloid osmotic swelling. Cell volume was determined by optical density and intracellular water measurements. Transmembrane pH and electrical gradients were determined by the distribution of the weak acid benzoate and lipophilic cation tetraphenylphosphonium respectively. Cells incubated in sodium chloride without glucose exhibited a progressive fall in ATP over several hours. When ATP fell below 40 uM the cells swelled, leaked protein and became permeable to inulin. Subsequent addition of glucose induced shrinkage and restored the original permeability properties. Energized cells exhibited an electrochemical gradient of protons of up to 130 mV, inside negative and alkaline. The proton-ATPase inhibitor dicyclohexylcarbodiimide (DCCD), which collapsed the chemical and electrical components of the proton gradient, induced rapid swelling despite high ATP levels thus implicating the proton gradient in volume regulation. Either the pH gradient or the membrane potential could maintain volume. Energy-dependent sodium efflux in exchange for protons was demonstrated in sodium-loaded cells using radioactive sodium and 9-aminoacridine fluorescence to follow sodium and proton translocation respectively.

• Research Organization: Harvard Univ., Cambridge, MA (USA)
• OSTI ID: 6409448
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
ATP
BIOSYNTHESIS
BACTERIA
HOMEOSTASIS
CELL MEMBRANES
PERMEABILITY
BENZOIC ACID
CATIONS
ELECTROPHYSIOLOGY
FLUORESCENCE
GLUCOSE
INULIN
PH VALUE
PROTONS
SODIUM ISOTOPES
TRACER TECHNIQUES
VOLUME
ALDEHYDES
ALKALI METAL ISOTOPES
BARYONS
CARBOHYDRATES
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CHARGED PARTICLES
ELEMENTARY PARTICLES
FERMIONS
HADRONS
HEXOSES
IONS
ISOTOPE APPLICATIONS
ISOTOPES
LUMINESCENCE
MEMBRANES
MICROORGANISMS
MONOCARBOXYLIC ACIDS
MONOSACCHARIDES
NUCLEONS
NUCLEOTIDES
ORGANIC ACIDS
ORGANIC COMPOUNDS
PHYSIOLOGY
POLYSACCHARIDES
SACCHARIDES
SYNTHESIS
550701* - Microbiology- Tracer Techniques