Preprint Thermosensitivity of translation underlies the mammalian nocturnal-diurnal switch, 2023, Beale et al.

Thermosensitivity of translation underlies the mammalian nocturnal-diurnal switch
Andrew David Beale; Nina M Rzechorzek; Andrei Mihut; Aiwei Zeng; Nicola J Smyllie; Violetta Pilorz; Rose Richardson; Mads F Bertlesen; Nathan R James; Shaline V Fazal; Zanna Voysey; Jerry Pelletier; Priya Crosby; Sew Y Peak-Chew; Madeline A Lancaster; Roelof A. Hut; John S O'Neill

Early mammals were nocturnal until the Cretaceous-Paleogene extinction facilitated their rapid expansion into daytime niches.

Diurnality subsequently evolved multiple times, independently, but the mechanisms facilitating this switch are unknown. We found that physiological daily temperature shifts oppositely affect circadian clock rhythms in nocturnal versus diurnal mammals. This occurs through a cell-intrinsic signal inverter, mediated by global differences in protein phosphorylation, and effected at the level of bulk protein synthesis rates, with diurnal translation rate being less thermosensitive than nocturnal. Perturbations that reduce translational initiation or mTOR activity are sufficient to trigger the nocturnal-to-diurnal switch at the cellular, tissue, and organismal scale.

Our results suggest a convergent selection pressure to attain diurnality by reducing the effect of temperature-dependent changes in protein synthesis on circadian clocks.

One sentence summary: Recalibrating the thermosensitivity of protein synthesis drives daytime-selective activity in mammals.

Link | PDF (Preprint: BioRxiv)

 

Somewhat oblique title, but interesting read to see links between nutrient sensing, mTORC and circadian rhythms.

 

From what I understood the liver has its own circadian rythm that is influenced by and influences feeding and fasting behaviour.

I learned about this by observing how I could not handle skipping meals around 17:00 but could easily tolerate moving my dinner to 17:00 and not eating afterwards (instead of eating around 19:00-20:00). And this earlier dinner also seemed to help me fall asleep because eating for me is very energizing for a few hours. Once this observation was made, I began reading about circadian clocks and learned about the liver circadian clock. I'm not sure if changing the feeding time alters the sleep-wake rythms but it seems plausible.

Edit: it seems that the liver does have some influence

Liver cells control our biological clock
https://www.cnrs.fr/en/liver-cells-control-our-biological-clock

 

Also some interesting implications for translational research when studying mice and trying to apply in human clinical trials. Eg Potential circadian effects on translational failure for neuroprotection (2020, Nature) —

 

I think this is really badly written.

And this is hyperbolic Malapropism to the point of falsehood. Recapitulation means following the preexisting pattern of development, which this did not. It achieved a superficially comparable behaviour through in vitro manipulation of lymphocytes with metabolic blockers.

( edit to add - Likewise, eliciting a diurnal response by starving normally nocturnal mice is not shown to be the recapitulation of the diurnal evolution of other taxa in former epochs. This behavioural response is a current potentially adaptive response to environmental conditions but that does not mean it is due to the same unidentified genetic changes which allowed the selection of diurnal behaviour in other species. The claim of recapitulation is overblown and misconceived. Even if they meant that the mouse reverted to the diurnal behaviour which preceded the evolution of nocturnal behaviour, that is not recapitulation, I don't know the correct term but it would carry the sense of reversion.)

I read obscurantist word salad aka BS.

(Sorry I know that is rude and bad tempered. Mea culpa.)