Respiratory oscillations in yeast: clock-driven mitochondrial cycles of energization.
Respiratory oscillations in continuous yeast cultures can be accounted for by cyclic energization of mitochondria, dictated by the demands of a temperature-compensated ultradian clock with a period of 50 min. Inner mitochondrial membranes show both ultrastructural modifications and electrochemical potential changes. Electron transport components (NADH and cytochromes c and c oxidase) show redox state changes as the organisms cycle between their energized and de-energized phases. These regular cycles are transiently perturbed by uncouplers of energy conservation, with amplitudes more affected than period; that the characteristic period is restored after only one prolonged cycle, indicates that mitochondrial energy generation is not part of the clock mechanism itself, but is responding to energetic requirement.
Lloyd
David
D
Microbiology (BIOSI 1, Main Building), Cardiff University, P.O. Box 915, Cardiff, UK. lloydd@cf.ac.uk
Eshantha
L
L
Salgado
J
J
Turner
Michael P
MP
Murray
Douglas B
DB
D000204:Activity Cycles / Q000187:drug effects / Q000502:physiology*; D001683:Biological Clocks / Q000187:drug effects / Q000502:physiology*; D019069:Cell Respiration / Q000502:physiology*; D003574:Cytochrome c Group / Q000378:metabolism; D003576:Electron Transport Complex IV / Q000378:metabolism; D004734:Energy Metabolism; D008928:Mitochondria / Q000378:metabolism*; D009243:NAD / Q000378:metabolism; D010084:Oxidation-Reduction; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000378:metabolism*; D013057:Spectrum Analysis; D013696:Temperature; D014475:Uncoupling Agents / Q000494:pharmacology
D003574:Cytochrome c Group; D014475:Uncoupling Agents; D009243:NAD; D003576:Electron Transport Complex IV