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This Week in PNAS: May 24, 2016

Editor's Note: Some of the articles described below are not yet available at the PNAS site, but they are scheduled to be posted some time this week.

In the early, online edition of the Proceedings of the National Academy of Sciences, researchers from the University of Texas at Austin present a reporter system for tracking intron gain and loss events in the yeast model organism Schizosaccharomyces pombe. With this strategy — which uses an artificial intron in a construct with fluorescent protein and amino acid reporters — the team detected two cases of intron gain by transposition in S. pombe, leading to artificial intron introduction at the RPL8B and ADH2 gene loci. "This is, to our knowledge, the first demonstration of intron gain via intron transposition in any organism," the authors write, "and we suggest that these events are likely to have occurred by a reversal of the pre-[messenger RNA] splicing reaction followed by homologous recombination."

A team from Singapore and the US explore the role that RUNX transcription factor phosphorylation plays in mitotic progression for another PNAS paper. Using a cell cycle synchronized human cell line, the researchers followed RUNX regulation over time, uncovering enhanced phosphorylation of a specific residue in the RUNX3 transcription factor during mitosis. This RUNX3 phosphorylation seems to interfere with the protein's ability to bind DNA, the investigators found, leading to shifts in the distribution of other RUNX proteins that ultimately prompt entry into mitosis.

Finally, a team from the UK and the US uses targeted lipidomic experiments in mice to assess inflammatory events governed by the lipid metabolizing CYP450 enzymes. By following the production of lipids called epoxy-oxylipins during acute inflammation and inflammation resolution in mice with peritonitis, the researchers found evidence for a role for CYP450-produced epoxy-oyxlipins in dampening the inflammatory monocyte buildup as the inflammatory process subsides. "These findings demonstrate that epoxy-oxylipins have a critical role in monocyte lineage recruitment and activity to promote inflammatory resolution and represent a novel internal regulatory system governing the establishment of adaptive immunity," the study's authors write.

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