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This Week in PNAS: May 3, 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 US and China describe a genetic method designed to date ancient samples based on genome sequence information and recombination clock data. "The idea is that an ancient genome has evolved less than the genomes of present-day individuals," the Broad Institute's David Reich and colleagues write, "and thus has experienced fewer recombination events since the common ancestor." In its proof-of-principle experiments, the team applied this strategy to date five ancient samples that had been radiocarbon dated at 12,000 years to 45,000 years old, using a combination of recombination clues and Neanderthal admixture to come up with ages for the genomes that coincided well with their previously estimated ones.

A Belgian team takes a look at genetic polymorphisms present in the genome of an inbred mouse strain called SPRET/Ei, descended from the Algerian mouse, Mus spretus. Tapping into data generate by the Wellcome Trust Sanger Institute's Mouse Genomes Project, the researchers examined the protein-coding sites affected by SNPs and small insertions and deletions in the SPRET/Ei genome. Their results suggest almost one-third of protein-coding genes in SPRET/Ei contain a polymorphism compared with the mouse reference genome, generated for the C57BL/6J M. musculus strain. With the help of their bioinformatics tool, the study's authors narrowed in on nonsense mutation expected to alter the amino acid sequence of the resulting gene — a collection included in a related M. spretus database.

Finally, researchers from the University of Washington report on findings from a targeted sequencing search for TP53 mutations in peritoneal fluid from women with or without ovarian cancer. For the study, slated to appear in PNAS this week, the team used duplex sequencing to find low-frequency mutations in samples from 17 women with high-grade serous ovarian cancer and 20 unaffected controls, uncovering low-frequency TP53 mutations in samples from all but two of the cases and controls. The mutation burden in TP53 was enhanced in individuals with ovarian cancer, suggesting it may eventually be possible to use mutation burden as a biomarker for the disease. GenomeWeb has more on the study, here.