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This Week in PNAS: Jul 8, 2014

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 edition of the Proceedings of the National Academy of Sciences, a team from the US and China characterized the extent to which heteroplasmic mitochondrial mutations occur in participants from the 1,000 Genomes Project. The team identified more than 4,300 heteroplasmies in all, with some 90 percent of study participants carrying at least one such mitochondrial DNA alteration. Roughly one-fifth of individuals had heteroplasmic mutations implicated in disease, though the most pathogenic heteroplasmies were present at relatively low frequency. "The prevalence of mitochondrial heteroplasmy with high pathogenic potential in healthy individuals, along with the possibility of these mutations drifting to high frequency inside a sub-population of cells across a lifespan, emphasizes the importance of managing mitochondrial heteroplasmy to prevent disease progression," the investigators note.

Sleep deprivation can lead to a decline in the plasma levels of some metabolites, according to another PNAS study. A team from the UK and the Netherlands did liquid chromatography and mass spectrometry-based testing of 171 metabolites in plasma samples from a dozen healthy male participants over a normal day and after 24 hours of sleeplessness. The patterns detected suggest that plasma metabolite levels tend to rise and fall in a predictable manner during normal sleep cycles. After sleep deprivation, though, the researchers saw higher-than-usual plasma levels of 27 of the metabolites tested. GenomeWeb Daily News has more on the study, here.

Finally, researchers from Columbia University, Rockefeller University, and elsewhere used small RNA sequencing on heart tissues samples from dozens of individuals to search for circulating or myocardial microRNAs associated with heart failure. Using information on 34 individuals with heart failure from different causes, eight unaffected controls, and five fetal samples, the team detected sets of miRNAs associated with heart failure from dilated cardiomyopathy or from ischemic cardiomyopathy. The study's authors argue that their results so far highlight the possibility of miRNA targeting therapies and potential of finding heart injury biomarkers.