A.M. and P.M. clocks: fruit fly brain has double timekeepers.
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 United States, officially United States of America, republic (2005 est. pop. 295,734,000), 3,539,227 sq mi (9,166,598 sq km), North America. The United States is the world's third largest country in population and the fourth largest country in area. , 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 cluck researcher William J. Schwartz of the University of Massachusetts Medical School UMMS is ranked fourth in primary care education among the nation’s 125 medical schools in the 2006 U.S.News & World Report annual guide, “America’s Best Graduate Schools”. UMMS is also a major center for research. 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 Verb 1. bustle about - move or cause to move energetically or busily; "The cheerleaders bustled about excitingly before their performance"
bustle, hustle in the morning and then slow down until a second peak of activity in the evening. Fruit flies in a lab can anticipate the usual turning on of lights in the morning, starting to move about even in the dark. In the evening, the lab flies likewise get more active shortly before lights-out.
In the 1970s, researchers proposed that such patterns come from dual built-in pace-makers, rather than just one. Each pace-maker would control one of the daily activity peaks.
In each hemisphere of the fly brain, clock genes are active in six clusters of neurons. Francois Rouyer's lab at Alfred Fessard Institute of Neurobiology Neurobiology
Study of the development and function of the nervous system, with emphasis on how nerve cells generate and control behavior. The major goal of neurobiology is to explain at the molecular level how nerve cells differentiate and develop their in Gif-sur-Yvette examined three clusters situated toward the outside of the hemisphere. The researchers worked with mutant flies with no daily rhythms because one of their clock genes, per, doesn't work.
When researchers introduced a working per gene into the lower two of the outside clusters, designated the ventral ventral /ven·tral/ (ven´tral)
1. pertaining to the abdomen or to any venter.
2. directed toward or situated on the belly surface; opposite of dorsal.
adj. lateral neurons, the morning activity peak showed up. The evening peak, however. didn't. When the researchers restored gene function in both the upper and lower clusters, both morning and evening activity reappeared.
The same neuron clusters attracted the attention of Michael Rosbash of Brandeis University Brandeis University, at Waltham, Mass.; coeducational; chartered and opened 1948. Although Brandeis was founded by members of the American Jewish community, the university operates as an independent, nonsectarian institution. in Waltham, Mass., and his colleagues. They took a different approach, disabling the upper or lower brain clusters. Those flies with disabled lower clusters didn't show a strong morning peak, and those with disabled upper clusters, called dorsal lateral neurons, didn't behave normally in the evening.
The team also found evidence that the two clocks interact.
"These are really, really satisfying papers," says Steve Kay of the Scripps Research Institute in La Jolla, Calif. He comments that a view of circadian rhythm circadian rhythm: see rhythm, biological.
Inherent cycle of approximately 24 hours in length that appears to control or initiate various biological processes, including sleep, wakefulness, and digestive and hormonal activity. as a single feedback loop is giving way to a more elaborate vision that includes many interlocking interlocking /in·ter·lock·ing/ (-lok´ing) closely joined, as by hooks or dovetails; locking into one another.
interlocking Obstetrics A rare complication of vaginal delivery of twins; the 1st cycles.