References

376 E. Wagner et al.
The circadian rhythmic cell (cyanobacterial and eukaryotic) is considered
to be a hydro-electrochemical oscillator (Wagner et al. 1997) synchronised
by the daily light–dark cycles, with temporal compartmentation of
metabolism and a network of metabolic sequences to compensate for oxidative
stress in adapting to the light environment, e.g. by separating nitrogen
fixation from photosynthetic oxygen production (Sherameti et al. 2002).
25.5
Circadian Rhythmic Organisation of Energy
Metabolism in C. rubrum and the Gating
of Photoreceptor (Phytochrome) Action
In C. rubrum a circadian rhythm in overall energy transduction has been
observed. The rhythm results from an oscillatory network between glycolysis
and oxidative phosphorylation, coupled to photophosphorylation. This
network produces a circadian rhythm in adenylate energy charge and redox
state (NADP/NADPH2). The nucleotide ratios themselves could act as
rate effectors in compartmental feedback and thus fulfil the requirements
of precise temperature-compensated time-keeping (Wagner et al. 1975,
Table 25.2. Rhythmic organisation of metabolism in Chenopodium rubrum (the period
lengths of the subpeaks are in parentheses) (Complemented after Bünning 1977)
Phenomenon Period length (h)
Photoperiodic light sensitivity 30
Betacyanine accumulation 24–30 (15)
Betacyanine turnover 24–30
Adenylate kinase activity 30 (15)
Energy charge (ATP + 1/2 ADP/ATP + ADP + AMP) 21–24 (11–13)
NADPH2/NADP ratio 21–24
Dark respiration 21–24
Chlorophyll accumulation 15
Net photosynthesis 15
Triose phosphate dehydrogenase activity (NADH2;NADPH2) 15
Malate dehydrogenase activity 12–15
Glutamate dehydrogenase activity 12–15
Glucose-6-phosphate dehydrogenase activity 12–15
Gluconate-6-phosphate dehydrogenase activity 12–15
Pyridine nucleotide, pool size [NAD(H2); NADP(H2)]
Turgor-controlled growth phenomena
12–15 (6)
Stem extension rate 23–27
Leaf movement 23–27