All life forms on Earth use the same genetic alphabet of the bases A, T, C, and G—nitrogen-containing compounds that constitute the building blocks of DNA and spell out the instructions for making proteins. Now, scientists have developed the first bacterium to use extra letters, or unnatural bases, to build proteins. The traditional four DNA bases code for 20 amino acids, but the addition of new letters X and Y could produce up to 152 amino acids, which might become building blocks for new drugs and novel materials, the scientists say.
A long-standing challenge in physics has been finding evidence for dark matter, the stuff presumed to make up a substantial chunk of the mass of the universe. Its existence seems to be responsible for the structure of the universe and the formation and evolution of galaxies. But physicists have yet to observe this mysterious material. Results reported Wednesday by a China-led space science mission provide a tantalizing hint—but not firm evidence—for dark matter.
When Dutch researchers developed an open-source algorithm named statcheck to flag statistical errors in psychology papers, it received mixed reactions from the research community—especially after the free tool found that tens of thousands of published papers contained statistical inconsistencies. Some scientists have called these studies a “form of harassment,” and others have questioned the accuracy of the tool itself. Now, a new study by statcheck’s developers—posted to a preprint server this week—suggests their algorithm gets it right in more than 95% of cases. Expect that result to be checked.
A spectacular fossil find is providing tantalizing new clues about the habits of pterosaurs, ancient flying reptiles that lived at the same times as dinosaurs. The cache of more than 200 fossil eggs found with bones of juvenile and adult animals in northwestern China suggests to some researchers that pterosaur parents may have cared for their newly hatched young. In a paper published Thursday in Science, researchers report that a 3-meter-square chunk of rock they excavated contains 16 eggs with the fossilized bones of developing embryos.
Hikers in Tibet and the Himalayas need not fear the monstrous yeti—but they’d darn well better carry bear spray. Previous genetic analyses of a couple of “yeti” hair samples collected in India and Bhutan suggested that a stretch of their mitochondrial DNA resembled that of polar bears. That finding hinted that a previously unknown type of bear, possibly a hybrid between polar bears and brown bears, could be roaming the Himalayas. Now, DNA analyses of nine samples purported to be from the “abominable snowman” reveal that eight actually came from various species of bears native to the area.