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This Week in PNAS: Nov 5, 2013

In the early, online edition of the Proceedings of the National Academy of Sciences, the Chinese University of Hong Kong's Dennis Lo and colleagues present findings from a bisulfite sequencing study of DNA circulating in the blood that revealed lower-than-usual methylation in individuals with the liver cancer hepatocellular carcinoma and other cancer types. Results of their analysis indicate that it's possible to use the sequencing strategy to not only distinguish between DNA from individuals with or without breast, lung, liver, and other cancer types in a non-invasive manner, but also to track treatment progression and pick up copy number patterns in individuals' tumors, in some cases.

Researchers from the Scripps Institution of Oceanography and the University of California, San Diego, describe the glycogenomics-based scheme they used to find and characterize bioactive glycosylated natural products from microbes. Using a combination of genomics and mass spectrometric metabolomics, the team worked back from glycosyl groups identified by mass spec to the sets of microbial genes coding for them. By applying the glycogenomic approach to bacteria from Salinispora arenicola and a Streptomyces species, for instance, the study's authors uncovered an antibiotic showing promise against multi-drug resistant Staphylococcus aureus, along with a known anticancer compound.

Finally, a team from Tufts University and Duke University Medical School explore the genome instability consequences of so-called interstitial telomeric sequences in the yeast model Saccharomyces cerevisiae. Results of their reporter gene experiments indicated that these intersitial sequences — telomere-like repeats found in the middle rather than the ends of chromosomes — are marked not only by an especially high rate of small insertions and deletions, but also by pronounced chromosomal rearrangements. "Because we previously found that [yeast telomeric] repeats cause strong replication fork stalling," authors of the study note, "we suggest that formation of double-stranded DNA breaks within the [yeast telomeric] sequences might be responsible for these gross chromosome rearrangements."