No abstract

Behind the heavy black curtains of his microscopy room, Mark Miller is shooting an action movie. He gives the settings on the multiphoton microscope a onceover while his senior scientist Vjollca Konjufca checks the sedated mouse on the warmed stage. Then Miller flicks a switch on the scanner and red, blue and green images flicker on the computer monitor. He points to what he's looking for. "Right there, " he says. Blue-labelled Salmonella bacteria gather near the top of a red villus, a finger-like projection from the wall of the mouse's small intestine. The bacteria look like helicopters buzzing around a mountain. It's early afternoon, and we are settling in to watch these bacteria for the next hour.Miller's experiments, and others like it, are not just gripping the audience behind the curtain -they are gripping a much broader audience of immunologists. Miller, at Washington University School of Medicine in St Louis, Missouri, runs one of the leading labs using multiphoton microscopy to watch infections in living animals in real time.Less than a decade ago, Miller and other immunologists mostly studied the process of infection in vitro, mixing pathogens and the cells they interact with in a culture dish. These simulations had their limits because the cells, much like animals in a zoo, were removed from the environment that influences their behaviour. The advent of multiphoton microscopy allowed researchers to view deep inside living tissues and watch cell biology live and 'in the wild' . This is particularly valuable for the