This mouse egg (top) is being injected with genetic material from an adult cell to ultimately create an embryo — and, eventually, embryonic stem cells. The process has been difficult to do with human cells.
James King-Holmes/Science Source
In this colored transmission electron micrograph, an infected cell (reddish brown) releases a single Ebola virus (the blue hook). As it exits, the virus takes along part of the host cell's membrane (pink, center), too. That deters the host's immune defenses from recognizing the virus as foreign.
London School of Hygiene & Tropical Medicine/Science Source
The research team used yeast chromosome No. 3 as the model for their biochemical stitchery. Pins and white diamonds in the illustration represent "designer changes" not found in the usual No. 3; yellow stretches represent deletions.
Until recently, finding characteristic stone and bone tools was the only way to trace the fate of the Clovis people, whose culture appeared in North America about 13,000 years ago.
Sarah L. Anzick/Nature