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This Week in PNAS: Jul 12, 2016

In the early, online edition of the Proceedings of the National Academy of Sciences, a Harvard University researcher discusses evidence for apparent natural selection in humans in the US. Jonathan Beauchamp tapped data from individuals in the Health and Retirement study, a population cohort comprised of individuals of European descent born between 1931 and 1953. Based on polygenic scores for features ranging from height and weight to schizophrenia risk, he saw signs of slow selection against variants implicated in educational attainment. There were also hints of selection acting on variants involved in puberty age in women, he notes, suggesting "humans are still evolving — albeit slowly and at a rate that cannot account for more than a small fraction of the large changes that have occurred over the past few generations."

Investigators from Stanford University present results from an analysis of pluripotent stem cell differentiation in the human otic lineage, leading to the otic placode and inner ear development. With a combination of single-cell gene expression profiles, monolayer cultures, and cell signaling analyses, the team tracked the inner ear's developmental trajectory in vitro, uncovering clues to the development of diverse otic cell types over time with clues from the surrounding microenvironment. "[W]e reconstructed the development trajectory of single cells based on their intrinsic temporal order orchestrated by the transcriptional dynamics as [human embryonic stem cells] and [induced pluripotent stem cells] are guided toward [the non-neural ectoderm] and, ultimately, in the direction of otic cells," the study's authors write.

A Duke University- and University of California, Los Angeles-led team describes similarities between gene expression patterns in former child soldiers from Nepal and those previously described in individuals from industrialized, western locales facing adverse life conditions. Using dried blood spots collected five years after a civil war in Nepal, the researchers assayed gene expression in 154 former child soldiers and 136 matched civilian controls. Their results suggest a so-called conserved transcriptional response to adversity — marked by a rise in pro-inflammatory and a dip in anti-viral gene expression — was enhanced in former children soldiers, particularly those with more severe post-traumatic stress disorder. GenomeWeb has more on the study, here.