GENETIC AND MOLECULAR ANALYSIS OF CIRCADIAN-RHYTHMS

The first part of this review summarizes the two best understood aspec ts of the two best understood circadian systems, the feedback oscillat ors of Neurospora and Drosophila, concentrating on what we know about the frequency (frq), period (per), and timeless (tim) genes. in the se cond part, the general circadian genetic and molecular literature is s urveyed, with an eye to describing what is known from a variety of sys tems about input to the oscillator (entrainment), and how the oscillat or might work and be temperature compensated, in emerging systems incl uding Synechococcus, Gonyaulax, Arabidopsis, hamsters, and mice. Final ly, the conservation of the molecular components of clocks is analyzed : both frq and per are widely conserved in their respective phylogenet ic classes. Pharmacological data suggest that most other organisms use a day-phased oscillator of the type seen in Neurospora rather than a night-phased oscillator such as in Drosophila.