Researchers at the University of Gothenburg have developed a method to study single cells while exposing them to controlled environmental changes. The method employs a set of laser tweezers to move the cells around in a microscopic channel system, allowing the team to study how single cells react to stress induced by a constantly changing environment.Studies on how cells react to changes in their environment, such as reduced availability of nutrients, have traditionally used cultures consisting of millions of cells. Although such studies show how cells on average react, they say nothing about individual variation; for example, how quickly a single cell responds.Dr. Emma Eriksson and her colleagues in the university’s department of physics used laser tweezers to catch a 1-μm cell and move it between environments. Placing the cell in a system of channels made of silicone enabled them to add and remove substances so that the environment surrounding a single cell changes in a split second – while at the same time watching the reactions through a microscope.The image shows yeast cells tagged with a green flourescent protein that has been stressed with sodium chloride. Courtesy of Emma Eriksson and Elzbieta Petelenz.In its first stage, the method has been tested on yeast cells. The researchers tagged one of the cells’ proteins with a green fluorescent protein, enabling them to trace movements of the protein within a cell while it adjusts to a new environment.“The information gained from this may eventually lead to a better understanding of how cells work and what they do to stay alive and healthy in a constantly changing environment,” Eriksson said.