OWLEDGE

irst there was green fluorescent pro-tein (GFP) from jellyfish, then came red fluorescent protein (DsRed) from coral. Now researchers from the Univer-sity of California at Irvine show that DsRed may become equally indispens-able for tracking cells, organelles, and fusion proteins by turning them... green? Ian Parker says he and his colleagues made the discovery quite by accident while exploring the use of DsRed for multiphoton confocal imaging. Brief exposure to a femtosecond-pulsed laser beam turned DsRed’s fluorescence from F DsRed-expressing cells before (upper) and after (lower) “greening ” of the cyto-plasm (left) or nucleus (right). Pa rk er /M a