Demasking biological oscillators: properties and principles of entrainment exemplified by the Neurospora circadian clock.
Oscillations are found throughout the physical and biological worlds. Their interactions can result in a systematic process of synchronization called entrainment, which is distinct from a simple stimulus-response pattern. Oscillators respond to stimuli at some times in their cycle and may not respond at others. Oscillators can also be driven if the stimulus is strong (or if the oscillator is weak); i.e., they restart their cycle every time they receive a stimulus. Stimuli can also directly affect rhythms without entraining the underlying oscillator (masking): Drivenness and masking are often difficult to distinguish. Here we use the circadian biological clock to explore properties of entrainment. We confirm previous results showing that the residual circadian system in Neurospora can be entrained in a mutant of the clock gene frequency (frq(9), a strain deficient in producing a functional FRQ protein). This finding has implications for understanding the evolution of circadian programs. By comparing data sets from independent studies, we develop a template for analyzing, modeling, and dissecting the interactions of entrained and masked components. These insights can be applied to oscillators of all periodicities.
Roenneberg
Till
T
Centre for Chronobiology, Institute of Medical Psychology, Medical Faculty, University of Munich, Goethestrasse 31, D-80336 Munich, Germany. roenneberg@lmu.de
Dragovic
Zdravko
Z
Merrow
Martha
M
D000392:Air Movements; D001683:Biological Clocks / Q000502:physiology*; D005075:Biological Evolution; D002940:Circadian Rhythm / Q000502:physiology*; D005656:Fungal Proteins / Q000235:genetics / Q000502:physiology*; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D009492:Neurospora crassa / Q000502:physiology*; D012098:Reproduction / Q000502:physiology; D013696:Temperature
C087405:FRQ protein, Neurospora crassa; D005656:Fungal Proteins