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Circadian rhythms are known to modulate memory, but it’s not known whether clock genes in the hippocampus are required for memory consolidation. Here, the authors show that epigenetic regulation of clock gene Period1 in the hippocampus regulates memory and contributes to age-related memory decline, independent of circadian rhythms.

The catalytic subunit E9 of the vaccinia virus DNA polymerase forms a functional polymerase holoenzyme by interacting with the heterodimeric processivity factor A20/D4. Here the authors present the structure of full-length E9 and show that an insertion within its palm domain binds A20, in a mode different from other family B polymerases.

Aging is accompanied by impairments in both circadian rhythmicity and long-term memory. Although it is clear that memory performance is affected by circadian cycling, it is unknown whether age-related disruption of the circadian clock causes impaired hippocampal memory. Here, we show that the repressive histone deacetylase HDAC3 restricts long-term memory, synaptic plasticity, and experience-induced expression of the circadian gene Per1 in the aging hippocampus without affecting rhythmic circadian activity patterns. We also demonstrate that hippocampal Per1 is critical for long-term memory formation. Together, our data challenge the traditional idea that alterations in the core circadian clock drive circadian-related changes in memory formation and instead argue for a more autonomous role for circadian clock gene function in hippocampal cells to gate the likelihood of long-term memory formation.

Abstract The multi-phase oxidation of S(IV) plays a crucial role in the atmosphere, leading to the formation of haze and severe pollution episodes. We here contribute to its understanding on a molecular level by reporting experimentally determined pK a values of the various S(IV) tautomers and reaction barriers for SO2 formation pathways. Complementary state-of-the-art molecular-dynamics simulations reveal a depletion of bisulfite at low pH at the liquid-vapor interface, resulting in a different tautomer ratio at the interface compared to the bulk. On a molecular-scale level, we explain this with the formation of a stable contact ion pair between sulfonate and hydronium ions, and with the higher energetic barrier for the dehydration of sulfonic acid at the liquid-vapor interface. Our findings highlight the contrasting physicochemical behavior of interfacial versus bulk environments, where the pH dependence of the tautomer ratio reported here has a significant impact on both SO2 uptake kinetics and reactions involving NO x and H2O2 at aqueous aerosol interfaces.

HNF4A is a nuclear receptor that regulates liver lipid homeostasis. Here the authors show that HNF4A is not required for intestinal lipid metabolism but controls energy expenditure under diet induced obesity through the fat-induced release of glucose-dependent insulinotropic polypeptide.

Understanding strong X-ray induced phenomena is important for applications of X-ray free-electron laser imaging. Here, the authors show time-resolved measurements of X-ray free-electron laser induced electronic decay of CH2I2 molecule probed with NIR pulses and identify mechanisms behind different transient states lifetimes.

Brown adipose tissue (BAT) takes up and burns fatty acids for thermogenesis in mice. Here the authors use PET to show that, in humans, cold stimulation increases BAT dietary fatty acid uptake from plasma and oxidative metabolism, although, unlike mice, human BAT takes up less fatty acids than other metabolic tissues.