Temperature-amplitude coupling for stable biological rhythms at different temperatures

Area of Science:

• Chronobiology
• Systems Biology
• Molecular Biology

Background:

• Biological processes typically speed up with temperature.
• Circadian rhythms, however, maintain a stable period despite temperature changes, a phenomenon known as temperature compensation.
• This stability is puzzling as individual biochemical reactions are temperature-sensitive.

Purpose of the Study:

• To investigate the mechanism behind the temperature compensation of circadian rhythms.
• To determine if amplitude changes in clock gene expression contribute to period stability.
• To explore the generality of this mechanism in other biological rhythms.

Main Methods:

• Measured time series of circadian clock transcripts (Cry1, Dbp) in cultured C6 glioma cells at different temperatures.
• Analyzed mathematical models of circadian clock networks with varying topologies.
• Revisited data from the yeast metabolic cycle (YMC) to assess amplitude-temperature coupling.

Main Results:

• Circadian expression amplitudes of Cry1 and Dbp increased significantly with temperature.
• Mathematical models indicated that increased geometric mean amplitude is necessary for period stability at higher temperatures.
• Yeast metabolic cycle amplitude also increased with temperature, supporting a common mechanism.

Conclusions:

• Temperature-amplitude coupling, where increased gene expression amplitude compensates for faster reaction rates, is a key mechanism for circadian period stability.
• This mechanism appears to be shared by both circadian rhythms and the yeast metabolic cycle.
• Understanding this coupling provides insights into the robustness of biological timing mechanisms.