Bora D. Zivkovic

Works (5)

Updated: July 5th, 2023 16:02

2003 journal article

Ocular clocks are tightly coupled and act as pacemakers in the circadian system of Japanese quail

AMERICAN JOURNAL OF PHYSIOLOGY-REGULATORY INTEGRATIVE AND COMPARATIVE PHYSIOLOGY, 284(1), R208–R218.

By: C. Steele n, B. Zivkovic n, T. Siopes* & H. Underwood*

author keywords: melatonin; body temperature; eye; circadian; Coturnix
MeSH headings : Animals; Biological Clocks / physiology; Body Temperature; Circadian Rhythm / physiology; Coturnix / physiology; Eye / chemistry; Female; Male; Melatonin / analysis; Melatonin / blood; Ocular Physiological Phenomena; Photoperiod
TL;DR: The ability to maintain phase in DD and rapidly recouple after out-of-phase entrainment demonstrates that the eyes are strongly coupled pacemakers that work in synchrony to drive circadian rhythmicity in Japanese quail. (via Semantic Scholar)
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Added: August 6, 2018

2001 journal article

Circadian organization and the role of the pineal in birds

MICROSCOPY RESEARCH AND TECHNIQUE, 53(1), 48–62.

By: H. Underwood n, C. Steele n & B. Zivkovic n

author keywords: avian; melatonin; suprachiasmatic nucleus; extraretinal photoreception; ocular pacemaker
MeSH headings : Animals; Biological Clocks / physiology; Birds / anatomy & histology; Birds / physiology; Circadian Rhythm / physiology; Female; Gonadal Steroid Hormones / physiology; Hypothalamus / physiology; Male; Ocular Physiological Phenomena; Photoreceptor Cells, Vertebrate / physiology; Pineal Gland / physiology; Reproduction; Suprachiasmatic Nucleus / physiology
TL;DR: All organisms exhibit significant daily rhythms in a myriad of functions from molecular levels to the level of the whole organism, showing that they are driven by an internal circadian clock. (via Semantic Scholar)
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2000 journal article

Circadian ovulatory rhythms in Japanese quail: Role of ocular and extraocular pacemakers

JOURNAL OF BIOLOGICAL RHYTHMS, 15(2), 172–183.

By: B. Zivkovic n, H. Underwood n & T. Siopes n

author keywords: Japanese quail; circadian; ovulation; internal coincidence; retina; extraretinal photoreception
MeSH headings : Animals; Blindness / physiopathology; Body Temperature; Circadian Rhythm / physiology; Coturnix / physiology; Female; Ocular Physiological Phenomena; Oviposition; Ovulation / physiology; Photoperiod; Photoreceptor Cells, Vertebrate / physiology; Sensory Deprivation / physiology; Vision, Ocular / physiology
TL;DR: The results do not show a role for ocular pacemakers in the control of ovulation, but they do support the hypotheses that entrainment of the central oscillators by extraretinally perceived light is sufficient to preserve a normal ovulatory pattern in LD in the absence of the ocularpacemakers. (via Semantic Scholar)
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1999 journal article

Effects of fasting on the circadian body temperature rhythm of Japanese quail

PHYSIOLOGY & BEHAVIOR, 66(1), 137–143.

By: H. Underwood n, C. Steele n & B. Zivkovic n

author keywords: circadian; temperature rhythm; fasting; activity rhythm; quail
MeSH headings : Animals; Blindness / physiopathology; Body Temperature / physiology; Circadian Rhythm / physiology; Coturnix / physiology; Fasting / physiology; Female; Photoreceptor Cells / physiology
TL;DR: Measurements of activity levels before and during fasting indicate that fasting-induced hypothermia cannot be explained simply as a consequence of decreases in activity levels, and food deprivation was also observed to cause significant phase shifts in the endogenous rhythm of body temperature. (via Semantic Scholar)
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1999 journal article

Formal properties of the circadian and photoperiodic systems of Japanese quail: Phase response curve and effects of T-cycles

JOURNAL OF BIOLOGICAL RHYTHMS, 14(5), 378–390.

By: B. Zivkovic n, H. Underwood*, C. Steele n & K. Edmonds n

author keywords: Japanese quail; circadian rhythms; photoperiodism; reproduction; phase response curve; T-cycles
MeSH headings : Animals; Body Temperature / physiology; Circadian Rhythm / physiology; Coturnix / physiology; Female; Motor Activity / physiology; Oviposition / physiology; Ovulation / physiology; Photoperiod; Time Factors
TL;DR: Studies of the circadian and photoperiodic system of Japanese quail showed that the circadian system acts like a low-amplitude oscillator: It is readily reset by light without significant transients, has a Type 0 phase response curve (PRC), and has a large range of entrainment. (via Semantic Scholar)
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Added: August 6, 2018

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