Daily rhythms of food-anticipatory behavioral activity do not require the known circadian clock.
When food availability is restricted to a particular time each day, mammals exhibit food-anticipatory activity (FAA), a daily increase in locomotor activity preceding the presentation of food. Considerable historical evidence suggests that FAA is driven by a food-entrainable circadian clock distinct from the master clock of the suprachiasmatic nucleus. Multiple food-entrainable circadian clocks have been discovered in the brain and periphery, raising strong expectations that one or more underlie FAA. We report here that mutant mice lacking known circadian clock function in all tissues exhibit normal FAA both in a light-dark cycle and in constant darkness, regardless of whether the mutation disables the positive or negative limb of the clock feedback mechanism. FAA is thus independent of the known circadian clock. Our results indicate either that FAA is not the output of an oscillator or that it is the output of a circadian oscillator different from known circadian clocks.
Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA.
Kai-Florian
KF
Storch
Charles J
CJ
Weitz
D056930:ARNTL Transcription Factors; D000204:Activity Cycles; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000172:deficiency / Q000378:metabolism; D001683:Biological Clocks / Q000502:physiology*; D018797:Cell Cycle Proteins / Q000378:metabolism; D002940:Circadian Rhythm / Q000502:physiology*; D003624:Darkness; D005247:Feeding Behavior / Q000502:physiology*; D047908:Intracellular Signaling Peptides and Proteins / Q000172:deficiency / Q000378:metabolism; D051379:Mice; D009154:Mutation / Q000235:genetics; D009687:Nuclear Proteins / Q000172:deficiency / Q000378:metabolism; D056950:Period Circadian Proteins; D014157:Transcription Factors / Q000172:deficiency / Q000378:metabolism
D056930:ARNTL Transcription Factors; D051792:Basic Helix-Loop-Helix Proteins; D018797:Cell Cycle Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009687:Nuclear Proteins; D056950:Period Circadian Proteins; D014157:Transcription Factors; C538961:Bmal1 protein, mouse; C539023:Per1 protein, mouse; C513312:Per2 protein, mouse