Cell-population interrelations in mechanisms of the circadian rhythm of proliferation in lingual epithelium of mice exposed to continuous light

1984 ◽  
Vol 97 (3) ◽  
pp. 330-332
Author(s):  
V. P. Rybakov
Keyword(s):  
Circadian Rhythm ◽  
Cell Population ◽  
Continuous Light ◽  
Lingual Epithelium

Frequency Resonances of the Circadian Rhythm of CAM Under External Temperature Rhythms of Varied Period Lengths in Continuous Light*

Botanica Acta ◽  
1996 ◽  
Vol 109 (5) ◽  
pp. 422-426 ◽  
Author(s):  
U. Lüttge ◽  
T. E. E. Grams ◽  
Bettina Hechler ◽  
B. Blasius ◽  
F. Beck
Keyword(s):  
Circadian Rhythm ◽  
Continuous Light ◽  
External Temperature ◽  
Temperature Rhythms

Circadian rhythm and response to light of extracellular glutamate and aspartate in rat suprachiasmatic nucleus

1996 ◽  
Vol 271 (3) ◽  
pp. R579-R585 ◽  
Author(s):  
S. Honma ◽  
Y. Katsuno ◽  
K. Shinohara ◽  
H. Abe ◽  
K. Honma
Keyword(s):  
Circadian Rhythm ◽  
Suprachiasmatic Nucleus ◽  
Light Pulse ◽  
Continuous Light ◽  
In Vivo Microdialysis ◽  
Dark Phase ◽  
Dark Cycle ◽  
Complete Darkness ◽  
Endogenous Circadian Rhythm

Extracellular concentrations of glutamate and aspartate were measured in the vicinity of rat suprachiasmatic nucleus (SCN) by means of in vivo microdialysis. The concentrations of both excitatory amino acids (EAAs) were higher during the dark phase than during the light under the light-dark cycle, showing pulsatile fluctuations throughout the day. When rats were released into the complete darkness, the 24-h pattern in the aspartate continued for at least one cycle, whereas that in the glutamate disappeared. The nocturnal increases in the EAA levels were not due to the increase of locomotor activity during the nighttime, because the 24-h rhythms were also detected in animals under urethan anesthesia. The patterns of extracellular EAA levels were changed when rats were released into the continuous light. Circadian rhythm was not detected in the glutamate, whereas the 24-h pattern was maintained in the aspartate with the levels increased to various extents. A 30-min light pulse given either at zeitgber time (ZT) 1 or ZT 13 elevated the EAA levels during the latter half of the light pulse, except glutamate by a pulse at ZT 1. The extracellular EAA levels in the vicinity of the rat SCN showed the circadian rhythm with a nocturnal peak and increased in response to the continuous light and a brief light pulse. The aspartate level is considered to be regulated by the endogenous circadian rhythm, but the glutamate levels seems to be modified by the light-dark cycle.

scholarly journals Circadian rhythm and cell population growth

2011 ◽  
Vol 53 (7-8) ◽  
pp. 1558-1567 ◽  
Author(s):  
Jean Clairambault ◽  
Stéphane Gaubert ◽  
Thomas Lepoutre
Keyword(s):  
Circadian Rhythm ◽  
Population Growth ◽  
Cell Population ◽  
Cell Population Growth

Effects of Bilateral Adrenalectomy and Continuous Light on the Circadian Rhythm of Corticotropin in Female Rats1

Endocrinology ◽  
1968 ◽  
Vol 82 (6) ◽  
pp. 1117-1124 ◽  
Author(s):  
PHILIP CHEIFETZ ◽  
NORMA GAFFUD ◽  
JOSEPH F. DINGMAN
Keyword(s):  
Circadian Rhythm ◽  
Continuous Light ◽  
Bilateral Adrenalectomy

scholarly journals DOES CHRYSANTHEMUM DISPLAY AN ENDOGENOUS CIRCADIAN RHYTHM OF STEM ELONGATION?

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1077f-1077
Author(s):  
Jason Tutty ◽  
Peter Hicklenton
Keyword(s):  
Circadian Rhythm ◽  
Constant Temperature ◽  
Dark Period ◽  
Stem Elongation ◽  
Continuous Light ◽  
Linear Displacement ◽  
Dendranthema Grandiflora ◽  
Diurnal Cycles ◽  
Diurnal Patterns ◽  
Endogenous Circadian Rhythm

The rate of internodal extension of chrysanthemum (Dendranthema grandiflora Tzvelev. cv. Envy) under various temperature and photoperiod conditions was studied to determine whether reproducible diurnal patterns of growth existed and whether any such patterns conformed to an endogenous circadian rhythm. Stem growth was monitored continuously by means of linear displacement voltage transducers. At constant temperature and under 11 h light/13 h dark photoperiod, stem elongation followed a clearly defined pattern consisting of a peak in rate immediately after the dark to light transition and then a gradual decline until the start of the dark period. During darkness, elongation rate increased and reached a maximum approximately 8 hours after the light to dark transition. This pattern differed when light period temperature was either above or below dark period temperature, but these patterns were also highly reproducible. When plants were subjected to continuous light at constant temperature, the rhythm of stem elongation initially showed a periodicity of approximately 27 hours. After 2 or 3 diurnal cycles the rhythm was less distinct and the rate became essentially constant. Furthermore, the interruption of a long period of continuous light with a 13 h dark period did not restore the rhythm. These findings do not support the existence of an endogenous circadian rhythm of stem elongation. Diurnally-cued rhythms do, however, exist and can be modified by temperature.

Semidian rhythmicity in the flowering response of Pharbitis nil to changes in temperature

1998 ◽  
Vol 25 (2) ◽  
pp. 183 ◽  
Author(s):  
O.M. Heide ◽  
R.W. King ◽  
L.T Evans
Keyword(s):  
Circadian Rhythm ◽  
Constant Temperature ◽  
Opposite Effect ◽  
Dark Period ◽  
Floral Induction ◽  
Continuous Light ◽  
The Other ◽  
Pharbitis Nil ◽  
Flowering Response ◽  
Short Day

Our earlier experiments on flowering in the short day plant Pharbitis nil involved far- red/dark (FR/D) interruptions of 90 min duration at various times during a continuous light, constant temperature period before a single inductive dark period. They revealed a rhythm with a period of 12 h, hence semidian. We concluded that the phasing of this semidian rhythm determined the length of darkness required for floral induction. This conclusion has since been challenged so we sought other pretreatments which reveal the semidian rhythm. Interruptions at 12°C–17°C for 45–90 min at various times prior to the inductive dark period were as effective as FR/D in eliciting the semidian rhythm, with significant effects on flowering persisting for at least three cycles in constant conditions in continuous light. The rhythmic response to 12°C pretreatments was 3 h out of phase with that to FR/D pretreatments. Flowering responses to the semidian rhythm exposed by 12°C pretreatments were additive to and independent of those to a circadian rhythm. Some evidence was obtained of reversal of the inhibition or promotion of flowering by FR/D or 12°C by exposure immediately afterwards to the other pretreatment at times of their opposite effect. Pretreatments at 12°C, like those with FR/D, either reduced (if promotive) or extended (if inhibitory) the length of the dark period required for floral induction in this short day plant.

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