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This Week in PNAS: Jan 22, 2013

In study slated to appear online this week in the Proceedings of the National Academy of Sciences, Max Planck Institute of Evolutionary Anthropology's Svante Pääbo and colleagues report on genetic findings for a 40,000-year-old human related to both Asian and Native American populations. The researchers sequenced the mitochondrial genome and a non-repetitive stretch of sequence from chromosome 21 using DNA from human remains found in Tianyuan Cave in northern China. They also profiled some 3,000 polymorphic regions in the ancient genome. Along with levels of Neandertal or Denisovan admixture on par with those found in mainland Asia today, the team found genetic patterns suggesting that "the Tianyuan individual derived from a population that was ancestral to many present-day Asians and Native Americans, but postdated the divergence of Asians from Europeans."

Vanderbilt University researchers explore the metabolomics consequences of drug resistance in a secondary metabolite-producing species of soil bacteria in another upcoming PNAS online study. The team deciphered transcriptional and translational shifts in antibiotic-resistant bacteria from the genus Nocardiopsis based on liquid chromatography and mass spectrometry profiles. In bugs resistant to streptomycin and rifampicin, the researchers' analyses uncovered widespread metabolomic alterations, including a jump in the repertoire of secondary metabolites produced by the resistant populations. "Taken together," they say, "these data suggest that biosynthetic pathway derepression is a general consequence of some antibiotic resistance mutations."

Finally, a team based in Belgium and France discuss how deep sequencing unearthed a set of viral microRNAs produced via non-canonical RNA polymerase III processes in a sheep model of B-cell leukemia/lymphoma that's induced using the bovine leukemia virus, or BLV. The researchers found 10 new miRNAs formed from five hairpin structures when they sequenced sets of RNAs from BLV-induced B-cell leukemias or lymphomas from sheep. "Altogether, our findings in the BLV leukemia model provide in vivo evidence of non-canonical tumor-associated miRNAs and lay the foundation for their functional study," senior author Anne Van den Broeke, with the University of Liège and the Free University of Brussels, and co-authors say.