Abstract
The circadian clock is a biological mechanism that permits some organisms to anticipate daily environmental variations. This clock generates biological rhythms, which can be reset by environmental cues such
as cycles of light or temperature, a process known as entrainment. After
entrainment, circadian rhythms typically persist with approximately 24
hours periodicity in free-running conditions i.e. in the absence of environmental cues. Experimental evidence also shows that a free-running period
close to 24 hours is maintained across a range of temperatures, a process
known as temperature compensation. In the plant Arabidopsis, the effect
of light on the circadian system has been widely studied and successfully
modelled mathematically. However, the role of temperature in periodicity, and the relationships between entrainment and compensation, are not
fully understood. Here we adapt recent models to incorporate temperature dependence by applying Arrhenius equations to the parameters of
the models that characterize transcription, translation, and degradation
rates. We show that the resulting models can exhibit thermal entrainment
and temperature compensation, but that these phenomena emerge from
physiologically different sets of processes. Further simulations combining
thermal and photic forcing in more realistic scenarios clearly distinguish
between the processes of entrainment and compensation, and reveal temperature compensation as an emergent property which can arise as a result
of multiple temperature-dependent interactions. Our results consistently
point to the thermal sensitivity of degradation rates as driving compensation and entrainment across a range of conditions.
as cycles of light or temperature, a process known as entrainment. After
entrainment, circadian rhythms typically persist with approximately 24
hours periodicity in free-running conditions i.e. in the absence of environmental cues. Experimental evidence also shows that a free-running period
close to 24 hours is maintained across a range of temperatures, a process
known as temperature compensation. In the plant Arabidopsis, the effect
of light on the circadian system has been widely studied and successfully
modelled mathematically. However, the role of temperature in periodicity, and the relationships between entrainment and compensation, are not
fully understood. Here we adapt recent models to incorporate temperature dependence by applying Arrhenius equations to the parameters of
the models that characterize transcription, translation, and degradation
rates. We show that the resulting models can exhibit thermal entrainment
and temperature compensation, but that these phenomena emerge from
physiologically different sets of processes. Further simulations combining
thermal and photic forcing in more realistic scenarios clearly distinguish
between the processes of entrainment and compensation, and reveal temperature compensation as an emergent property which can arise as a result
of multiple temperature-dependent interactions. Our results consistently
point to the thermal sensitivity of degradation rates as driving compensation and entrainment across a range of conditions.
| Original language | English |
|---|---|
| Journal | Journal of circadian rhythms |
| DOIs | |
| Publication status | Published - 14 May 2019 |