How a Circadian Rhythm Clock Is Imitated by an Artificial Chemical Clock

How a Circadian Rhythm Clock Is Imitated by an Artificial Chemical Clock ...

Researchers developed a clever temperature compensation technique based on the Belousov-Zhabotinsky (BZ) oscillating reaction.

Circadian rhythms are natural, internal oscillations that synchronize an organism's behaviors and physiological processes with their environment. They are normally monitored by internal chemical clocks that respond to external stimuli, such as light.

Circadian rhythms all share an enigmatic characteristic—temperature does not affect them at all, even though the rate of most biochemical reactions changes exponentially with temperature. This suggests that some sort of temperature-compensation mechanism is at play. However, these reactions often require extremely precise adjustments.

What if there were a more straightforward method of achieving temperature compensation in an oscillating chemical reaction? A group of researchers led by Assistant Professor Yuhei Yamada of Tokyo Institute of Technology (Tokyo Tech), Japan, devised a clever temperature compensation technique using a reaction known as the Belousov–Zhabotinsky (BZ) oscillating reaction.

Tokyo Tech is crediting them.

The key to their approach are soft, temperature-responsive gels made from poly(N-isopropylacrylamide), or 'PNIPAAm' for short, with which the BZ reaction may occur. However, because these gels shrink as temperature increases, the amount of solvent contained in the gel decreases.

The researchers added ruthenium (Ru) sites to PNIPAAm gels to exploit this property. The researchers' investigation of the particular BZ reaction relied partially on the back-and-forth oxidation and reduction of ruthenium (Ru) ions. The relative concentrations of solvent and Ru in the gels vary with temperature.

The abovementioned effects combine to form a temperature-compensation mechanism that permits the duration of the BZ reaction to be unaffected by changing temperature, according to Yamada.

This research demonstrates a completely different technique to manipulate temperature compensation in artificial biological clocks based on periodic reactions: "Our research suggests that temperature compensation mechanisms using temperature-responsive soft bodies may exist in biological systems in nature."

Let's hope that future research will help clarify the mysteries of our internal clocks!

Yuhei Yamada, Hiroshi Ito, and Shingo Maeda, "Artificial temperature-compensated biological clock with temperature-sensitive Belousov–Zhabotinsky gels," Scientific Reports, 27 December 2022. DOI: 10.1038/s41598-022-27014-z

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