232
D. Lloyd
an interwoven ensemble of oscillators, rhythms, and timekeepers acting on different
time scales but integrated as a heterarchy and therefore with no dominant central
control.
14.1.8 Oscillations in Glycolysis
The first report of oscillating concentrations of NADH, a cofactor in intact living
organisms was in suspensions of anaerobic yeast cells by Duysens and Amesz [27].
This observation appears not to have been immediately followed up by these investigators or elsewhere until, following electrical activity in the muscle of the electric
eel, transients in metabolites were analysed [115]. A decade later, [113] interest in a
baker’s yeast as an excellent model system for spectrophotometric and fluorometric
studies was rekindled and analysed in detail were reviewed in an essential text for
anyone studying oscillating biological systems [16], and their computer simulations.
No clear-cut function has been assigned to glycolytic oscillatory dynamics [88]. It
has however provided many insights into control mechanisms, especially in mutant
strains, (e.g., [106, 114]). The recognition of feedback control and allosteric enzyme
regulation has helped to elucidate the molecular mechanisms involved in some of
these cases, the most clearly understood system is still the high-frequency (approximately 2 min
−1 ) glycolytically-associated oscillations in the yeast Saccharomyces
carlsbergensis, (reclassified as a strain of S. cerevisiae).
Thereby yeast glycolytic oscillations are the most defined systems, as are their
interactions with mitochondria and plasma membranes [131, 139]. In yeast displaying
glycolytic oscillations, coupling of the dynamics of glycolytic ATP and NADH and
the extent of dipolar relaxation of intracellular water is synchronized via the action
of the cytoskeleton and affects membrane functions [156].
14.1.9 Cellular Respiratory Oscillations
In 1973 Mochan and Pye [121] pointed out that respiratory oscillations in yeast
cultures during growth involve redox changes in mitochondrial cytochrome components.
Degn [24] suggested that oscillatory behaviour in general (e.g., not only in NADH,
but also in the fluorometrically detected oxidized form of flavins [25, 26], might
indicate sloppy-control under certain conditions.
In 1980, Bashford et al. [7] obtained fluorometric evidence for redox cycling in
Schizosaccharomyces pombe, and in Acanthamoeba castellanii: in both organisms
each of the coenzymes showed short-periods of 4.5 ± 1.0 min.
Oscillating mitochondrial membrane potentials in yeast have been observed using
fluorimetry by Andersen et al. [4], and dynamically imaged by Aon et al. [5].
D. Lloyd
an interwoven ensemble of oscillators, rhythms, and timekeepers acting on different
time scales but integrated as a heterarchy and therefore with no dominant central
control.
14.1.8 Oscillations in Glycolysis
The first report of oscillating concentrations of NADH, a cofactor in intact living
organisms was in suspensions of anaerobic yeast cells by Duysens and Amesz [27].
This observation appears not to have been immediately followed up by these investigators or elsewhere until, following electrical activity in the muscle of the electric
eel, transients in metabolites were analysed [115]. A decade later, [113] interest in a
baker’s yeast as an excellent model system for spectrophotometric and fluorometric
studies was rekindled and analysed in detail were reviewed in an essential text for
anyone studying oscillating biological systems [16], and their computer simulations.
No clear-cut function has been assigned to glycolytic oscillatory dynamics [88]. It
has however provided many insights into control mechanisms, especially in mutant
strains, (e.g., [106, 114]). The recognition of feedback control and allosteric enzyme
regulation has helped to elucidate the molecular mechanisms involved in some of
these cases, the most clearly understood system is still the high-frequency (approximately 2 min
−1 ) glycolytically-associated oscillations in the yeast Saccharomyces
carlsbergensis, (reclassified as a strain of S. cerevisiae).
Thereby yeast glycolytic oscillations are the most defined systems, as are their
interactions with mitochondria and plasma membranes [131, 139]. In yeast displaying
glycolytic oscillations, coupling of the dynamics of glycolytic ATP and NADH and
the extent of dipolar relaxation of intracellular water is synchronized via the action
of the cytoskeleton and affects membrane functions [156].
14.1.9 Cellular Respiratory Oscillations
In 1973 Mochan and Pye [121] pointed out that respiratory oscillations in yeast
cultures during growth involve redox changes in mitochondrial cytochrome components.
Degn [24] suggested that oscillatory behaviour in general (e.g., not only in NADH,
but also in the fluorometrically detected oxidized form of flavins [25, 26], might
indicate sloppy-control under certain conditions.
In 1980, Bashford et al. [7] obtained fluorometric evidence for redox cycling in
Schizosaccharomyces pombe, and in Acanthamoeba castellanii: in both organisms
each of the coenzymes showed short-periods of 4.5 ± 1.0 min.
Oscillating mitochondrial membrane potentials in yeast have been observed using
fluorimetry by Andersen et al. [4], and dynamically imaged by Aon et al. [5].