Transmission Processes Between Clock and Manifestations

Mills, J. N.

doi:10.1007/978-1-4613-4565-7_2

Cited by 21 publications

(14 citation statements)

References 168 publications

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“…The exact explanation of these is unknown but effects of dietary intake after fasting during sleep are likely to be involved. The transient fall in phosphate excretion in the hours after waking might be attributed to falling concentrations of phosphate in the plasma during this time (Mills, 1973;. The t.s.s.…”

Section: Discussionmentioning

confidence: 91%

Irregularity of rest and activity: studies on circadian rhythmicity in man.

Minors¹,

Nicholson²,

Spencer³

et al. 1986

The Journal of Physiology

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SUMMARY1. Rectal temperature, electrolyte excretion and performance were studied in young adults who followed an irregular pattern of work and rest for 9 days in an isolation unit.2. In the analysis, effects evoked by the pattern of work and rest were separated from the oscillatory component, and rhythms for individual days were examined by the cosinor method.3. During the schedule, rhythms no longer showed a period of exactly 24 h, and this effect was confirmed by studies using a repeated cycle of irregular work and rest and by studies using constant routines.4. Temperature and urinary constituents differed in the strength and phase of their rhythms when corrected for evoked effects, as well as in the strength of the evoked effects themselves.5. There was evidence of deterioration in performance during work periods which exceeded 9 h, but there was no evidence of progressive deterioration in performance over the 9 day schedule.

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Section: Discussionmentioning

confidence: 91%

Irregularity of rest and activity: studies on circadian rhythmicity in man.

Minors¹,

Nicholson²,

Spencer³

et al. 1986

The Journal of Physiology

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“…It is uncertain how far the customary phase-locked rhythms on a usual nychthemeral existence represent a hierarchical system, in which the different components are passively driven by a single master clock (Mills, 1973) The means whereby an endogenous oscillator can be entrained by rhythmic events in the environment is also unknown, although some such process is continuously operative in maintaining a 24-hr period in rhythms which, in the absence of such environmental periodicities, usually free-run with a period longer than 24 hr (Mills et al 1974;Wever, 1975). A mechanism has been suggested for such 'phase-locking' in small nocturnal mammals and other more lowly organisms, derived from the observed phase shifts which result from single pulses of light, but the suggestion that a similar mechanism operates in man (Palmer, 1976) is devoid of experimental basis.…”

Section: Discussionmentioning

confidence: 99%

Adaptation to abrupt time shifts of the oscillator(s) controlling human circadian rhythms.

Mills¹,

Minors²,

Waterhouse³

1978

The Journal of Physiology

277

117

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SUMMARY1. Thirty-six subjects in an isolation unit were subjected to time shifts of 12 hr, or of 8 hr in either direction.2. The rhythms of body temperature and excretion of eight urinary constituents were studied before and after the shift, both on a usual nychthemeral routine and during 24 hr when they remained under constant conditions, awake, engaged in light, mainly sedentary activity, and consuming identical food and fluid every hour.3. The rhythms on nychthemeral routine were defined by fitting cosine curves. On constant routine the rhythm after the shift was cross-correlated with the original rhythm, either with variable delay (or advance) or with an additive mixture between this variably shifted rhythm and the unshifted or a fully shifted rhythm. The process yielding the highest correlation coefficient was accepted as the best descriptor of the nature of adaptation.4. A combination of two rhythms was observed more often for urinary sodium, chloride and phosphate than for other variables.5. Adaptation appeared to have proceeded further after westward than eastward shifts, and this difference was particularly noticeable for urinary potassium, sodium and chloride.6. Partial adaptation usually involved a phase delay, even after an eastward shift when a cumulative dAlay of 16 hr would be needed to achieve full adaptation and re-entrainment. 7. Observations under nychthemeral conditions often gave a false idea of the degree of adaptation. In particular, after an eastward shift the phase of the rhythms appeared to shift in the appropriate direction when studied under nychthemeral conditions whereas the endogenous oscillator either showed no consistent behaviour or, in the control of urate excretion, a shift in the wrong direction.8. The implications for people undergoing time shifts, in the course of shift work or transmeridional flights, are indicated.

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“…In man, circadian rhythms occur in a wide range of physiological and biochemical processes including drug tolerance and effectiveness, various metabolic activities, secretory processes and sleep patterns. These rhythms are of substantial interest in diagnostic and therapeutic medicine, as well as being largely responsible for jet lag and the somewhat similar symptoms associated with shift work (Mills, 1973;Moore-Ede, 1974;Johnson & Froberg, 1975;Moore-Fde, Sultzman & Fuller, 1982;Arent, Minors & Waterhouse, 1989).…”

Section: Occurrence Of Circadian Rhythmsmentioning

confidence: 99%

Tansley Review No. 37 Circadian rhythms: their origin and control

Wilkins

1992

New Phytologist

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SUMMARY This article reviews the circadian rhythm of carbon dioxide metabolism in leaves of the Crassulacean plant Bryophyllum (Kalanchoë) fedtsckenkoi which persists both in continuous darkness and a CO2‐free atmosphere, and in continuous light and normal air. Under both conditions the rhythm is due to the periodic activity of the enzyme phosphoenolpyruvate carboxylase (PEPc). The physiological characteristics of the rhythm are described in detail and, from these characteristics, hypotheses are advanced to account for both the generation of the rhythm and the regulation of its phase and period by environmental factors. The periodic activity of PEPc is ascribed to the periodic accumulation of an allosteric inhibitor, malate, in the cytoplasm and its subsequent removal either to the vacuole in continuous darkness, or by metabolism in continuous light. Also involved in the generation of the rhythm is a periodic change in the sensitivity of PEPc to malate inhibition due to the periodic phosphorylation and dephosphorylation of PEPc which changes its K1 by a factor of 10 from 30 to 0.3 mM and vice versa. This periodic phosphorylation of PEPc is apparently achieved by the periodic synthesis and breakdown of a PEPc kinase which phosphorylates the enzyme on a serine residue; dephosphorylation is achieved by a type 2A phosphatase which shows no rhythmic variation. The induction of phase shifts in the rhythm in continuous darkness and CO2‐free air has been explained in terms of light and high‐temperature activated gates or channels in the tonoplast which, when open, allow malate to diffuse between the vacuole and cytoplasm. For the rhythm in continuous light and normal air phase, control by environmental signals can be attributed to changes in the malate levels in critical cell compartments, or in particular cell populations such as the stomatal guard cells, due to regulation of the malate synthesizing enzyme system involving PEPc, and malic enzyme which is responsible for malate metabolism. The role of the stomata in the generation of the rhythm is also discussed. The biochemical events which appear to give rise to the well‐studied circadian rhythms in leaf movement in Samanea and Albizza, in luminescence in Gonyaulax polyedra and in the synthesis of the chlorophyll a/b binding protein are also reviewed in an attempt to identify similarities between these events and those involved in the Bryophyllum rhythm. Finally, the somewhat similar nature of the genes apparently responsible for circadian rhythmicity in Neurospora and Drosophila are discussed, and suggestions made for utilizing anti‐sense nucleic acid technology in the further elucidation of the critical biochemical events involved in the basic, temperature‐compensated circadian oscillator in living organisms.

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Transmission Processes Between Clock and Manifestations

Cited by 21 publications

References 168 publications

Irregularity of rest and activity: studies on circadian rhythmicity in man.

Irregularity of rest and activity: studies on circadian rhythmicity in man.

Adaptation to abrupt time shifts of the oscillator(s) controlling human circadian rhythms.

Tansley Review No. 37 Circadian rhythms: their origin and control

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