Endophytes are microbes that live inside plants — the ones tagged with a fluorescent dye in this image are found in poplars. The microbes gather nitrogen from the air, turning it into a form plants can use, a process called nitrogen fixation. Researchers are looking at how these microbes could be used to help crops like rice and corn make their own fertilizer. Sam Scharffenberger hide caption
Ancient artifacts smuggled into the U.S. and purchased by Hobby Lobby are shown at a May 2 event returning the artifacts to Iraq in Washington, D.C. The seized artifacts include cuneiform tablets from the little-known ancient city of Irisagrig. Win McNamee/Getty Images hide caption
In a file photo from 2004, a sign at the entrance to the Arrowhead Mountain Spring Water Company bottling plant, owned by Swiss conglomerate Nestlé, on the Morongo Indian Reservation near Cabazon, Calif. Damian Dovarganes/AP hide caption
An Indonesian ranger inspects a peat forest fire in Aceh province in July 2017. Indonesia, unlike most of the world, lost less overall tree cover than usual last year. Chaideer Mahyuddin/AFP/Getty Images hide caption
Asteroid Ryugu, photographed on June 26 by the Hayabusa2 spacecraft, was the Japanese mission's destination. The craft will travel alongside the asteroid for 18 months. JAXA, University of Tokyo and collaborators hide caption
"If my life were to end next week ... I want to feel like I have made a contribution," said Carol Martin, seen here holding her 2018 Boston Marathon medal. Jesse Costa/WBUR hide caption
In his new job overseeing health coverage for 1.2 million workers and their families, Atul Gawande says he hopes to find specific ways to make health care more efficient and the solutions exportable. Dan Bayer/The Aspen Institute via Flickr hide caption
A vaccine given during pregnancy protects the baby against whooping cough, but only about 50 percent of pregnant women get it. Nicole Xu for NPR hide caption
If you are bitten by a Lone Star tick, you could develop an unusual allergy to red meat. And as this tick's territory spreads beyond the Southeast, the allergy seems to be spreading with it. Robert Noonan/Science Source hide caption
Dr. Vinay Prasad is 35 and an assistant professor of medicine at Oregon Health and Science University in Portland, where he researches health policy, the high cost of drugs and evidence-based medicine. He has more than 21,000 followers on Twitter. Marvin Joseph/The Washington Post via Getty Images hide caption
A gas flare is seen at a natural gas processing facility near Williston, N.D. in 2015. A new study says the amount of methane leaking is more than government estimates. Matthew Brown/AP hide caption
A bald eagle flies over its nest in Middle River, Md., in 2009. Rob Carr/AP hide caption
