January: David D. Thomas
February: Elizabeth Austin-Minor
March: Juliette Lecomte
April: David Millar
May: Lukas Tamm
September: David Millar
September: Dongping Zhong
October: Jonathan V. Rocheleau
November: Yevgenya Grinblat
December: Michael Graner
Onset Of Circadian Time Keeping, How Do You Start The Clock?
Speaker: Dr. Jennifer Liang; Assistant Professor, Department of Biology, University of Minnesota Duluth
Time/Place: Thursday, Jan 27th at 3:00 pm, 130 SMed
Abstract: Entrainment of circadian clocks to environmental cues (e.g., photoperiod) ensures that daily biological rhythms stay in synchronization with the Earth's rotation. The vertebrate pineal organ has a conserved role in circadian regulation as the primary source of the nocturnal hormone melatonin. We are using the zebrafish as a model system to identify genes and tissue required to initiate and maintain circadian rhythms during development. In lower vertebrates, the pineal has an endogenous circadian clock as well as photoreceptive cells that regulate this clock. We have identified a cassette of pineal genes that are required for the special and temporal pattern of pineal rhythms. We have also discovered that tissues outside the pineal affect pineal rhythms. In mammals, the suprachiasmatic nucleus (SCN) is a major regulator of circadian rhythms in mammals and birds. We found that pineal rhythms are present in zebrafish mutants despite the absence of an SCN. However, in embryos that lack the SCN, the amplitude of pineal rhythms is attenuated. This suggests that endogenous factors within the pineal may interact with signals from other tissues to initiate rhythms in the pineal. Thus, zebrafish may serve as a model system for understanding how vertebrate embryos coordinate rhythms that are controlled by different circadian clocks and different tissues.