Open AccessRespiratory oscillations in yeast: mitochondrial reactive oxygen species, apoptosis and time; a hypothesis
Author(s) -
Lloyd David,
Lemar Katey M.,
Salgado L.Eshantha J.,
Gould Timothy M.,
Murray Douglas B.
Publication year - 2003
Publication title -
fems yeast research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.991
H-Index - 92
eISSN - 1567-1364
pISSN - 1567-1356
DOI - 10.1016/s1567-1356(03)00071-0
Subject(s) - biology , reactive oxygen species , yeast , oxygen , mitochondrion , apoptosis , respiratory system , microbiology and biotechnology , biochemistry , anatomy , chemistry , organic chemistry
Oscillatory metabolic activities occur more widely than is generally realised; detectability requires observation over extended times of single yeast cells or synchrony of individuals to provide a coherent population. Where oscillations in intracellular metabolite concentrations are observed, the phenomenon has been ascribed to sloppy control, energetic optimisation, signalling, temporal compartmentation of incompatible reactions, or timekeeping functions. Here we emphasise the consequences of respiratory oscillations as a source of mitochondrially generated reactive O 2 metabolites. Temporal co‐ordination of intracellular activities necessitates a time base. This is provided by an ultradian clock, and one result of its long‐term operation is cyclic energisation of mitochondria, and thereby the generation of deleterious free radical species. Our hypothesis is that unrepaired cellular constituents and components (especially mitochondria) eventually lead to cellular senescence and apoptosis when a finite number of respiratory cycles has occurred.