This confocal micrograph shows the tissue structures within the leaf of an Arabidopsis thaliana seedling, the model organism in plant genetics. The sample was fixed and stained with propidium iodide, which labels DNA, but was imaged four years later.
Over time, oxidation of the stain in different parts of the tissue provides different fluorescent properties, which researchers are using to study plant cellular architecture and gene activity.
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.