Visible Gene Expression in Aging Fly (IMAGE) University of Southern California Caption This is an aging fly containing an hsp22-GFP transgene. The fly is 65-days-old, which is roughly equivalent to 65-years-old for a human. The green color is the GFP fluorescence that indicates that the hsp22 gene has turned on in the old fly. The picture is an overlay of a visible light and GFP fluorescence images. Credit USC / John Tower laboratory Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.