S22
Regulatory Mechanisms of Biological Rhythm and Photoperiodism
Organizers:
Yoshitaka Fukada (Univ. Tokyo, Japan)
Satchidananda Panda (Salk Institute, USA)
Light is a very important ambient signal for animals, as it affords information for regulation of a variety of physiological functions, such as vision, circadian rhythms, photoperiodism, hormone regulation, pupil contraction, body color change, etc.. These responses are considered as being the outputs from the animals that utilize light information as a spatial cue or a temporal one. The latter aspect of light signaling is one of the particular issues that we would focus in this symposium. In circadian clock systems, the pace and phase of the central oscillator are regulated by ambient light, while an array of slave clocks present in a variety of peripheral tissues are regulated by non-photic signals. These clock systems converge on a significant daily variation of behavior and physiology. The regulatory mechanism of the connection among the central and peripheral clocks is another issue that is discussed in this session. The temporal information is further combined with signals from light onset and offset within the day, providing the basis for photoperiodism underlying seasonal regulation of animal physiology. Many other light-responses are also of particular importance. Recent studies in this decade have identified molecules and the mechanisms responsible for these chronobiological events and their photic and non-photic regulation.
Speakers:
1) Kyungjin Kim (Seoul National Univ., Korea)
Genetic and molecular approaches to the circadian clock system in mice.
2) Yoshitaka Fukada (Univ. Tokyo, Japan)
Light-dependent regulation of the chick pineal gene expression and functions.
3) Satchidananda Panda (Salk Institute, USA)
Light reception in rodent retinal ganglion cells and its role in the clockwork.
4) Takashi Yoshimura (Nagoya Univ., Japan)
How birds and mammals recognize the seasonal change of the daylength?
5) Hideharu Numata (Kyoto Univ., Japan)
Circannual rhythm in a beetle, and its relationship to the circadian clock.