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This Week in PLOS: May 18, 2015

In PLOS One, Brazilian researchers describe DNA barcodes that are showing promise for verifying the identity of medicinal plants used in herbal remedies. The team used barcode sequences in three genes to test more than 250 leaf, flower, and root samples, purchased from a market in Brazil between 2012 and 2014. It also assessed the chemical composition of the samples — which represented eight World Health Organization-approved medicinal plant species — using chromatography and spectroscopy. Along with their appraisal of the DNA barcodes, the study's authors looked at the prevalence of plant substitutions in the products, which occurred in as many as 71 percent of the samples.

A team from China and the US took a look at copy number and DNA methylation patterns in hepatocellular carcinoma cases that involve hepatitis B virus infection, focusing on features that may contribute to the altered expression of more than 1,000 inflammation-related genes. As they reported in PLOS One, the researchers detected hundreds of methylation, copy number, or expression changes in 30 hepatocellular carcinoma tumors and matched normal samples. Nevertheless, only a few dozen inflammation-related genes showed expression changes that consistently coincided with copy number changes, while expression shifts in 11 genes were associated with methylation shifts.

The bacterial species behind Q fever appears to have evolved from a tick endosymbiont that's passed down maternally, according to a paper in PLOS Pathogens. An international team led by investigators in France did PCR-based screening for the pathogen, Coxiella burnetii, in 916 representatives from 58 tick species. More than two-thirds of the ticks contained Coxiella, the researchers report. And their phylogenetic and whole-genome analyses suggest that C. burnetii began as an inherited endosymbiont that acquired the wherewithal to infect vertebrate cells relatively recently. "Identifying the evolutionary processes that transform symbiotic bacteria into emerging pathogens will require further exploration into the biology of the entire Coxiella genus," the study's authors say.