Written benefit finding for improving psychological health during the Covid-19 pandemic first wave lockdown.

Objectives. Written benefit finding is known to improve psychological and physical health in a range of patient groups. Here, we tested the efficacy of written benefit finding, delivered online during the Covid-19 pandemic lockdown, on mood and physical symptoms. We also investigated perseverative thinking as a moderator of these effects. Design. A quantitative longitudinal design was employed. Main Outcome Measures. Participants (n = 91) completed self-report measures of anxiety, depression, stress and physical symptoms at baseline, and two weeks after being randomised to complete three consecutive days of writing about the positive thoughts and feelings they experienced during the pandemic (written benefit finding) or to unemotively describe the events of the previous day (control). State anxiety was measured immediately before and after writing. Perseverative thinking was measured at baseline. Results. Anxiety and depression symptoms decreased between baseline and the two week follow-up, but did not differ significantly between the two conditions. Perseverative thinking was negatively associated with changes in symptoms of anxiety, depression and stress, but did not moderate any writing effects. There was a significant reduction in state anxiety in the written benefit finding condition. Conclusions. Written benefit finding may be a useful intervention for short-term improvements in wellbeing.

Multi-step recognition of potential 5' splice sites by the Saccharomyces cerevisiae U1 snRNP.

In eukaryotes, splice sites define the introns of pre-mRNAs and must be recognized and excised with nucleotide precision by the spliceosome to make the correct mRNA product. In one of the earliest steps of spliceosome assembly, the U1 small nuclear ribonucleoprotein (snRNP) recognizes the 5' splice site (5' SS) through a combination of base pairing, protein-RNA contacts, and interactions with other splicing factors. Previous studies investigating the mechanisms of 5' SS recognition have largely been done in vivo or in cellular extracts where the U1/5' SS interaction is difficult to deconvolute from the effects of trans-acting factors or RNA structure. In this work we used colocalization single-molecule spectroscopy (CoSMoS) to elucidate the pathway of 5' SS selection by purified yeast U1 snRNP. We determined that U1 reversibly selects 5' SS in a sequence-dependent, two-step mechanism. A kinetic selection scheme enforces pairing at particular positions rather than overall duplex stability to achieve long-lived U1 binding. Our results provide a kinetic basis for how U1 may rapidly surveil nascent transcripts for 5' SS and preferentially accumulate at these sequences rather than on close cognates.

Dicer's Helicase Domain: A Meeting Place for Regulatory Proteins.

The function of Dicer's helicase domain has been enigmatic since its discovery. Why do only some Dicers require ATP, despite a high degree of sequence conservation in their helicase domains? We discuss evolutionary considerations based on differences between vertebrate and invertebrate antiviral defense, and how the helicase domain has been co-opted in extant organisms as the binding site for accessory proteins. Many accessory proteins are double-stranded RNA binding proteins, and we propose models for how they modulate Dicer function and catalysis.

Chemical Inhibition of Pre-mRNA Splicing in Living Saccharomyces cerevisiae.

The spliceosome mediates precursor mRNA splicing in eukaryotes, including the model organism Saccharomyces cerevisiae (yeast). Despite decades of study, no chemical inhibitors of yeast splicing in vivo are available. We have developed a system to efficiently inhibit splicing and block proliferation in living yeast cells using compounds that target the human spliceosome protein SF3B1. Potent inhibition is observed in yeast expressing a chimeric protein containing portions of human SF3B1. However, only a single point mutation in the yeast homolog of SF3B1 is needed for selective inhibition of splicing by pladienolide B, herboxidiene, or meayamycin in liquid culture. Mutations that enable inhibition also improve splicing of branch sites containing mismatches between the intron and small nuclear RNA-suggesting a link between inhibitor sensitivity and usage of weak branch sites in humans. This approach provides powerful new tools for manipulating splicing in live yeast and studies of spliceosome inhibitors.