Heat-Shock or Red Light-Pulse Induced Circadian Rhythm in the Capacity for Chlorophyll Synthesis in Etiolated Bean or Pea Leaves

The effect of some respiratory inhibitors on light-induced Paulownia tomentosa Steud. seed germination was studied. Millimolar solution of sodium azide was sufficient to completely prevent germination induced by a 5-min red light pulse. The inhibitory effect of azide was absent if seeds were rinsed before phytochrome activation by light. Sodium azide was effective only if present in the period of Pfr activity. The escape time from azide inhibition compared to the escape from far-red light action, was delayed for about 24 hours. When azide was applied after phytochrome activation, its effect depended on how long it was present in the incubation medium. The removal of azide allowed full restoration of germination by another red light pulse and the far-red escape time did not differ from the escape of untreated, i.e. water-imbibed seeds. Potassium cyanide alone did not produce any effect in light-stimulated germination of these seeds. However, it counteracted the inhibitory effect of azide in light-stimulated germination, if applied simultaneously at a concentration three times higher.

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Circadian Rhythm of Output from Neurones in the Eye of Aplysia: III. Effects of Light on Clock and Receptor Output Measured in the Optic Nerve

Journal of Experimental Biology ◽

10.1242/jeb.70.1.183 ◽

1977 ◽

Vol 70 (1) ◽

pp. 183-194

Author(s):

JACK A. BENSON ◽

JON W. JACKLET

Keyword(s):

Circadian Rhythm ◽

Optic Nerve ◽

Circadian Clock ◽

Light Pulse ◽

Temperature Sensitivity ◽

Phase Point ◽

Light Onset ◽

Constant Illumination ◽

Light Pulses ◽

East West

1. The circadian rhythm of CAP frequency recorded from the optic nerve of isolated eyes at 15 °C was damped out by constant illumination (1100 lux) after several cycles of the rhythm. During illumination (LL) the rhythm was skewed with a rapid rising phase and slow falling phase, and the period was decreased by about 1 h. It is postulated that the circadian clock was stopped by LL at its lowest phase point, and that following cessation of LL, the rhythm was reinitiated from this phase point after a latency of 6-8 h. 2. For light pulses of 80 lux and 1100 lux, the photoresponse of the dark-adapted eye to 20 min light pulses applied beginning at 2 h intervals was not influenced by the circadian clock. At 5 lux there was a periodicity in the magnitude of the photoresponse, in phase with the circadian rhythm of spontaneous CAP production. 3. Small CAPs of non-circadian frequency were recorded together with normal CAPs in about 10% of records of output from isolated eyes. The cells producing the small CAPs had a different temperature sensitivity from those producing normal CAPs. The response of these cells to short light pulses consisted of a phasic burst of activity at light onset, followed by silence during the remainder of the short light pulse, and for 1 or 2 min following cessation of illumination. These small CAPs may be the activity either of H-type receptors or of secondary cells desynchronized from the major population. Note: Laboratory of Sensory Sciences, University of Hawaii at Manoa, 1993 East-West Road, Honolulu, Hawaii 96822, U.S.A.

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

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1996.271.3.r579 ◽

1996 ◽

Vol 271 (3) ◽

pp. R579-R585 ◽

Cited By ~ 3

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.

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Quantitative studies on ferredoxin in greening bean leaves

Biochemical Journal ◽

10.1042/bj1360697 ◽

1973 ◽

Vol 136 (3) ◽

pp. 697-703 ◽

Cited By ~ 27

Author(s):

B. G. Haslett ◽

R. Cammack ◽

F. R. Whatley

Keyword(s):

Red Light ◽

Chlorophyll Synthesis ◽

Paramagnetic Resonance ◽

Quantitative Studies ◽

Low Concentrations ◽

Electron Paramagnetic ◽

Linear Manner ◽

Cytoplasmic Ribosomes ◽

Mechanism Operative ◽

Bean Leaves

Two methods of measuring small amounts of the iron–sulphur protein ferredoxin are described. One involves measurements of the signal at g=1.96 produced by reduced ferredoxin in an e.p.r. (electron-paramagnetic-resonance) spectrometer; the other depends on the rate of ferredoxin-dependent electron transport in a chloroplast bioassay measured in an O2 electrode. These methods of measurement were used to examine the development of ferredoxin during the greening of etiolated bean leaves. Ferredoxin is present in low concentrations in the leaves and cotyledons of 14-day-old etiolated beans (Phaseolus vulgaris L. var. Canadian Wonder), and develops in a linear manner with time when the leaves are illuminated. This synthesis appears to be independent of chlorophyll synthesis during the early stages of greening. However, the chlorophyll/ferredoxin ratio reaches a final value of approx. 360 irrespective of the light intensity, indicating the existence of a control mechanism operative in deciding the stoicheiometry of these components in the mature chloroplast. The ferredoxin synthesis appears to be light-dependent, and red light is the most effective in its promotion. The effect of red illumination is not reversed by far-red light, indicating the absence of a phytochrome control of ferredoxin synthesis. From experiments using specific inhibitors of chloroplast protein synthesis, it is concluded that ferredoxin is synthesized on cytoplasmic ribosomes.

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A short red light pulse during dark phase of LD-cycle perturbs the hamster's circadian clock

Journal of Comparative Physiology A ◽

10.1007/bf00187636 ◽

1995 ◽

Vol 177 (6) ◽

Cited By ~ 12

Author(s):

G. Klante ◽

S. Steinlechner

Keyword(s):

Circadian Clock ◽

Light Pulse ◽

Red Light ◽

Dark Phase

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Possible Link Between Circadian Rhythm and Heat Shock Response in Neurospora Crassa

Chronobiology International ◽

10.3109/07420528709078546 ◽

1987 ◽

Vol 4 (4) ◽

pp. 543-549 ◽

Cited By ~ 20

Author(s):

L. Rensing ◽

A. Bos ◽

J. Kroeger ◽

G. Cornelius

Keyword(s):

Circadian Rhythm ◽

Heat Shock ◽

Neurospora Crassa ◽

Heat Shock Response ◽

Shock Response

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Reversion of the apical hook of pea in the dark and its promotion by a red light pulse.

Physiologia Plantarum ◽

10.1034/j.1399-3054.1990.780112.x ◽

1990 ◽

Vol 78 (1) ◽

pp. 75-78

Author(s):

Toshihiro Takagi ◽

Seiji Tsurumi ◽

Tohru Hashimoto

Keyword(s):

Light Pulse ◽

Red Light ◽

Apical Hook

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Control by Light Quality of Chlorophyll Synthesis in the Brown Alga Desmarestia aculeata

Zeitschrift für Naturforschung C ◽

10.1515/znc-1991-7-807 ◽

1991 ◽

Vol 46 (7-8) ◽

pp. 542-548 ◽

Cited By ~ 5

Author(s):

F. López-Figueroa

Keyword(s):

Blue Light ◽

Light Quality ◽

Red Light ◽

Green Light ◽

Chlorophyll Synthesis ◽

Natural Conditions ◽

Light Pulses ◽

Light Effects ◽

Starvation Conditions

Abstract The chlorophyll synthesis in the brown algae Desmarestia aculeata is affected by light quality and by the nutrient state in the medium before the illumination. Pulses of 5 min of red, green and blue light together with 200 μM nitrate in plants growing under natural conditions deter mined similar induction of chlorophyll synthesis. However, when the plants were incubated previously under starvation conditions the light effect was different. The induction of chlorophyll synthesis was greater after blue and green light than after red light pulses. Red-light photoreceptor was only involved in the chlorophyll synthesis under no nutrient limitations and under starvation conditions after previous illumination with blue light followed by far-red light. The induction of chlorophyll synthesis by green and blue light pulses applied together with nitrate was greater when the algae were incubated in starvation conditions than in natural conditions (normal nutrient state). Because all light effects were partially reversed by far-red light the involvement of a phyto-chrome-like photoreceptor is proposed. In addition, a coaction between blue-and a green-light photoreceptors and phytochrome is suggested.

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