Science  31 Jan 2014:
Vol. 343, Issue 6170, pp. 469

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  1. Acid Test Generates Stem Cells

    Restart. A mouse fetus created from STAP cells.


    Scientists have found yet another way of making stem cells that could have advantages over current methods. Researchers at Harvard Medical School in Boston and the RIKEN Center for Developmental Biology in Kobe, Japan, took differentiated cells from neonatal mice, subjected them to a moderately acidic environment for 25 minutes, and then returned them to a standard cell culture medium. A week later, cells that had survived the stress of the acid treatment had reverted to a pluripotent state—able to differentiate into nearly all cell types. Further culturing transformed what the researchers call stimulus-triggered acquisition of pluripotency (STAP) cells into self-renewing stem cells, the group reports in two papers in Nature this week.

    Previously, researchers have created pluripotent stem cells from embryos and by introducing proteins called transcription factors. The new STAP method avoids the ethical objections of using embryos and the genetic mutations that transcription factors sometimes induce. These benefits could make STAP stem cells useful for regenerative medicine applications if the procedure proves to work for human cells.

  2. Arizona's Grand Canyon a Patchwork of the Ages


    Is the Grand Canyon young or old, geologically speaking? A new study answers the much-debated question with a definitive … “both.” Geologists have few clues about the shape of the land tens of millions of years ago, but they have ways to guess. Rocks deeper in the crust are hotter, and they cool as a river removes overlying rock. The decay of certain elements tells scientists when a rock cooled to a certain temperature— and therefore when the overlying rock was removed and a canyon formed.

    A team of geologists and geochemists combined existing published data with some of their own for a new estimate: Two of the present canyon's five segments formed early on—one between 70 million and 50 million years ago, another between 25 million and 15 million years ago. But the two end segments were carved in the past 5 million to 6 million years, since the Colorado River first began flowing down the present canyon, they reported online on 26 January in Nature Geoscience. The nuanced view aims to put the debate to rest, but conflicting interpretations still abound.