Endogenous circadian rhythm in the photoperiodic ovarian response of the subtropical sparrow, Passer domesticus

1991 ◽  
Vol 50 (3) ◽  
pp. 637-639 ◽  
Author(s):  
G. Ravikumar ◽  
P.D. Tewary
Keyword(s):  
Circadian Rhythm ◽  
Passer Domesticus ◽  
Ovarian Response ◽  
Endogenous Circadian Rhythm

scholarly journals Involvement of a circadian rhythm in the photoperiodic ovarian response of the yellow-throated sparrow, Gymnorhis xanthocollis

1989 ◽  
Vol 143 (1) ◽  
pp. 411-418
Author(s):  
A. S. Dixit ◽  
P. D. Tewary
Keyword(s):  
Circadian Rhythm ◽  
Ovarian Response ◽  
Time Measurement ◽  
The Other ◽  
Phase Advance ◽  
Response System ◽  
Ovarian Growth ◽  
Endogenous Circadian Rhythm ◽  
Short Days

Groups of the photosensitive female yellow-throated sparrow were placed under various light-dark cycles, in which a fixed ultrashort photophase of 3 h was combined with dark phases of varying duration, resulting in cycles of 18–30 h. Simultaneously, two groups of birds, one in short days (8L/16D) and the other in long days (15L/9D), were kept as controls. Significant ovarian growth, observed at 30 and 60 days, was induced by 3 h ultrashort photophase only if it was introduced in the cycles of 18 h (3L/15D), 20 h (3L/17D), 26 h (3L/23D), 28 h (3L/25D) and 30 h (3L/27D) as well as under long days (15L/9D), whereas there was no response to the ultrashort photophase in cycles of 22 h (3L/19D) and 24 h (3L/21D) and in short days (8L/16D). It seems that there is an ovarian response to the ultrashort day cycles when a phase advance or delay of photosensitivity of the response system repeatedly produces coincidence of the external photophase (3 h) with the photosensitive phase of an endogenous circadian rhythm. The results are thus consistent with the Bunning hypothesis, which suggests the involvement of an endogenous circadian rhythm in photoperiodic time measurement.

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 0051 Altered Endogenous Circadian Rhythm of the Endocannabinoid Anandamide by Body Mass Index

SLEEP ◽  
2019 ◽  
Vol 42 (Supplement_1) ◽  
pp. A21-A22
Author(s):  
Nicole P Bowles ◽  
Saurabh S Thosar ◽  
Maya X Herzig ◽  
Noal A Clemons ◽  
Garrett Sauber ◽  
...  
Keyword(s):  
Body Mass Index ◽  
Circadian Rhythm ◽  
Body Mass ◽  
Endogenous Circadian Rhythm

Absence of Seasonal Variation in the Phase of the Endogenous Circadian Rhythm in Humans

1998 ◽  
Vol 15 (6) ◽  
pp. 623-632 ◽  
Author(s):  
Hans P. A. Van Dongen ◽  
Gerard A. Kerkhof ◽  
John H. M. Souverijn
Keyword(s):  
Circadian Rhythm ◽  
Seasonal Variation ◽  
Endogenous Circadian Rhythm

Microstructure of Fish Otoliths

1985 ◽  
Vol 42 (5) ◽  
pp. 1014-1032 ◽  
Author(s):  
Steven E. Campana ◽  
John D. Neilson
Keyword(s):  
Circadian Rhythm ◽  
Primary Source ◽  
Fish Growth ◽  
Age And Growth ◽  
Future Directions ◽  
Endogenous Circadian Rhythm ◽  
Increment Formation ◽  
Microstructure Examination ◽  
Morphological Differences ◽  
Source Of Error

Otolith microstructure examination has found an increasing number of applications in recent years. However, few workers have critically assessed the assumptions upon which the age and growth inferences are based or considered the potential for environmental modification of microstructural features. This paper reviews present applications and their assumptions and suggests future directions. Particular attention is given to the premises that the frequency of increment formation is constant and that the width of increments is proportional to fish growth. A hypothesis of increment formation is presented which appears consistent with the numerous and often conflicting studies reported to date. The presence of an endogenous circadian rhythm of increment formation is invoked, entrained by photoperiod, but susceptible to modification by other cyclic environmental variables. Increments formed as a result of the circadian rhythm (once per 24 h) may be induced by different processes than those induced through the action of environmental cues (often > 1 per 24 h), thus explaining apparent morphological differences in increment structure noted by some workers. Temperature fluctuations appear to be a primary source of subdaily increments and are a potential source of error in otolith interpretation.

scholarly journals Phosphorylation of the D1 Photosystem II Reaction Center Protein Is Controlled by an Endogenous Circadian Rhythm

2002 ◽  
Vol 130 (4) ◽  
pp. 2069-2075 ◽  
Author(s):  
Isabelle S. Booij-James ◽  
W. Mark Swegle ◽  
Marvin Edelman ◽  
Autar K. Mattoo
Keyword(s):  
Circadian Rhythm ◽  
Photosystem Ii ◽  
Reaction Center ◽  
Reaction Center Protein ◽  
Endogenous Circadian Rhythm
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