Respiratory Oscillations and Heat Evolution in Synchronously Dividing Cultures of the Fission Yeast Schizosaccharomyces pombe 972h-

Abstract

S U M M A R YLarge-scale synchronous cultures of the fission yeast Schizosaccharot?iyces/ionzbe 972h-were prepared by a sedimentation-velocity selection method in a zonal rotor.Oxygen uptake was measured polarographically on samples withdrawn at frequent intervals from the culture vessel. Rates of oxygen uptake, expressed per ml culture, increased exponentially, doubling over each cell cycle, but rose to maxima twice per cycle, once during cell division and once at approximately one-half of the cycle. Oxygen uptake at the maxima was stimulated by carbonyl-cyanide m-chlorophenyl hydrazone; that at the troughs was insensitive to this compound. Oxygen uptake was inhibited at all points in the cycle by antimycin A and cyanide at low concentrations; inhibition by these compounds did not alter the periodicity of the oscillations.Heat evolution increased at a constant rate during two cycles of synchronous growth, but in the presence of carbonyl-cyanide m-chlorophenyl hydrazone, peaks of heat evolution in phase with peaks of oxygen uptake were observed. The discontinuous respiratory activity of mitochondria through the cell cycle is discussed with reference to previous contrasting data, and possible control mechanisms are suggested .

The Influence of Growth Substrate and Capacity for Oxidative Phosphorylation on Respiratory Oscillations in Synchronous Cultures of Escherichia coli K12

“…These observations resemble those obtained with the highly-fermentative fission yeast Schizosaccharomyces pombe in three respects. (i) During the cell cycle of cells grown with glucose, the respiratory activity oscillates with a periodicity of half a cycle (Poole et al, 1973). (ii) Growth in the presence of a non-catabolite-repressive carbon source, glycerol, results in stepwise increases in O2 uptake (Poole & Lloyd, 1974).…”

“…Poole, Lloyd & Kemp, 1973). Similar experiments with E. coli were frustrated by the insensitivity or unreproducibility of the response of intact cells to a range of respiratory poisons.…”

Synchronous Cultures of Micro-organisms: Large-scale Preparation by Continuous-flow Size Selection

“…Cell volumes were calculated for at least IOO randomly selected cells from measurements with an image-splitting eyepiece (Poole, Lloyd & Kemp, 1973). …”

“…A major drawback of this method is the low yield. Scale-up has been achieved using the greater gradient capacity offered by zonal rotors (Poole, Lloyd & Kemp, 1973;. However, the time required for separation may be up to I h, during which the organisms are exposed to a sub-optimal temperature and anaerobic conditions.…”

Oxygen Uptake and Mitochondrial Enzyme Activities in the Mitotic Cycle of Physarum polycephalum

“…One possibility is that oscillations in a complex feedback control system are responsible for the respiratory pattern (Poole et al, 1973). Low frequency oscillations in the respiration 141 Oxygen uptake in Physarum .…”