Eye and gonad: role in the dual-oscillator circadian system of
female japanese quail.
Underwood, Herbert, Thomas Siopes, Kent Edmonds.
Department of Zoology and Department of Poultry Science, North
Carolina State University, Raleigh, NC 27695-7617, Department of
Biology, University of Massachusetts, Amherst, MA 01003
APStracts 3:0294R, 1996.
Experiments were conducted to determine the anatomical and
physiological basis of the dual-oscillator circadian system of female
Japanese quail. After blocking ocular light perception by eye
-patching, the circadian body temperature rhythm dissociates into two
circadian components in continuous lighting (LL). One component
freeruns with a period significantly shorter than 24 hrs (t=22.7 hr)
and is driven by an ocular pacemaker whereas the other component
freeruns with a period significantly longer than 24 hrs (t=26.3 hr).
The long freerunning rhythm is driven by the same circadian clock
that drives the circadian rhythm of ovulation. The expression of the
long freerunning rhythm in LL depends upon the presence of the ovary:
body temperature rhythmicity is abolished by ovariectomy. The two
freerunning oscillators in eye-patched birds showed evidence of
mutual interaction. Significantly, the phase-relationships that occur
as the two oscillators interact can determine whether or not
ovulation occurs. The results are discussed in terms of an
"internal coincidence" mechanism for photoperiodic time
measurement.
Received 29 February 1996; accepted in final form 9 July 1996.
APS Manuscript Number R125-6.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 4 August 1996