A green light for new research.

water on culture medium, let it incubate, and see if any bacterial colonies develop. But that technique demands lots of waiting, and you might prefer a quicker technique-say, one that allows you to watch the bacteria grow in real time. Laura Leff of the department of biological sciences at Kent State University in Ohio does just that-watches bacteria grow right before her eyes-by labeling them with green fluorescent protein (GFP). After introducing GFP into bacteria through standard genetic engineering techniques, she shines ultraviolet light on a sample of the bacteria, which stand out as green spots under a fluo-