Radiation and circadian effects are profoundly interconnected
The “escape from light” hypothesis proposes that circadian clocks evolved to anticipate the daily changes in light radiance and UV exposure.[1] Timing of sensitive processes such as nuclear division to avoid damage from ionizing wavelengths would be an evolutionary advantage and selected.[2,3]
The kaiC gene, a post-translational oscillator in cyanobacteria, is one example where both systems likely synergized: the gene family is monophyletic and current data suggest it emerged sometime between the last universal common ancestor (LUCA) and cyanobacteria.[4] KaiC shares similarities with RNA helicases and the ancestral kaiC may have derived from the RecA/DnaB DNA repair superfamily.[5]
References
- Jabbur ML, Johnson CH.
Spectres of Clock Evolution: Past, Present, and Yet to Come.
Front Physiol. 2022 Feb 11;12:815847.
https://doi.org/10.3389/fphys.2021.815847 - Pittendrigh CS.
Temporal organization: reflections of a Darwinian clock-watcher.
Ann Rev Physiol. 1993;55:17–54.
https://doi.org/10.1146/annurev.ph.55.030193.000313 - Nikaido SS, Johnson CH.
Daily and circadian variation in survival from ultraviolet radiation in Chlamydomonas reinhardtii.
Photochem Photobiol. 2000 Jun;71(6):758-65.
https://doi.org/10.1562/0031-8655(2000)0710758DACVIS2.0.CO2 - Dvornyk V, Vinogradova O, Nevo E.
Origin and evolution of circadian clock genes in prokaryotes.
Proc Natl Acad Sci U S A. 2003 Mar 4;100(5):2495-500.
https://doi.org/10.1073/pnas.0130099100 - Leipe DD, Aravind L, Grishin NV, Koonin EV.
The bacterial replicative helicase DnaB evolved from a RecA duplication.
Genome Res. 2000 Jan;10(1):5-16.
doi: 10.1101/gr.10.1.5
(doi inactive on Nov 21, 2025; alternate access via: https://genome.cshlp.org/content/10/1/5.long)