Mechanism of temperature compensation in circadian clocks
In plain words
Most chemical reactions speed up strongly when warmed, yet circadian clocks, the cell's 24-hour timers, keep nearly the same period over a wide range of temperatures. How the clock cancels the temperature dependence of its reactions is not understood.
Precise statement
For the KaiABC oscillator in vitro, the period has $Q_{10}$ of approximately 1.1 between about 298 and 308 K while individual rate constants have $Q_{10} \sim 2$ to 3 ($Q_{10}$ = rate ratio for a 10 K rise). Identify the mechanism (balanced activation energies of opposing reactions, temperature-insensitive KaiC ATPase, structural constraint) that makes $d \ln(\mathrm{period})/dT$ small, and predict the period's temperature dependence from measured rate constants.
What would settle it
A kinetic model built from independently measured temperature-dependent rate constants that predicts the period versus temperature and the effect of mutations that break compensation.