In all organisms,
internal clocks of govern the daily rhythms of the most basic functions like waking, eating, and sleeping. Haisun Zhu, Steven Reppert, and colleagues reveal the details of the clockwork in the
monarch butterfly and show that it has aspects of clocks from both the mouse and the fly, the only other
clock types known in animals. Since the mammalian orthologs of this protein play the same role in the mouse, it appears that Cry2 is the central timekeeper in two of the three known clocks (comparative genetic studies indicate Cry2 was lost in the Drosophila line). Two cryptochrome proteins, which act as critical components in an ancestral
circadian clock mechanism characterized in monarch butterflies, may also connect the clock to the sun compass for successful navigation Back in the brain, the authors showed that Cry2 was also found in a few dozen cells in brain regions previously linked to time-keeping in the butterfly, and this Cry2 underwent circadian oscillation in these cells, but not in many other cells that were not involved in time keeping.
More abstracts about the In Monarchs, Cry2 Is King of the Clock