A fruit fly relies on a different group of cells to tick out the rhythm to perk up in the morning than it does to boost evening activity after daytime doldrums, report two research teams.
Both teams performed experiments that altered the functions of cell clusters in each fly-brain hemisphere. Although the investigators, one team in France and the other in the United States, took different approaches, both groups pinpointed the same clusters of neurons for the morning- and the evening-activity increases. The two teams' papers appear in the Oct. 14 Nature.
"This is the first assignment of morning-ness and evening-ness to specific cells," comments clock researcher William J. Schwartz of the University of Massachusetts Medical School in Worcester.
The basic notion of dual control has been around for years, he says. Fruit flies, mice, and plenty of other organisms bustle about in the morning and then slow down until a second peak of activity in the evening. F