A new look at how genes unfold to enable their expression

Microscope image shows a portion of DNA strand (blue) containing heat shock genes (indicated by the dotted lines), which are highly condensed under normal conditions (top). When the temperature of cells is raised, heat shock genes undergo extensive disruption (below) as seen by the formation of large puffs (green), as the strand unpacks to make the gene available for expression. Credit: Janis Werner and John Lis