Seasons Greetings! What looks like a humble wreath actually represents an awe-inspiring gift to biomedical research: a new imaging technique that adds a dash of color to the formerly black-and-white world of electron microscopy (EM). Here the technique is used to visualize the uptake of cell-penetrating peptides (red) by the fluid-filled vesicles (green) of the endosome (gray), a cellular compartment involved in molecular transport. Without the use of color to draw sharp contrasts between the various structures, such details would not be readily visible.
This innovative technique has its origins in a wonderful holiday story. In December 2003, Roger Tsien, a world-renowned researcher at the University of California, San Diego (UCSD), decided to give himself a special present. With the lab phones still and email traffic slow for the holidays, Tsien decided to take advantage of the peace and quiet to spend two weeks alone at the research bench, pursuing an intriguing, yet seemingly wacky, idea. He wanted to find a way to deposit ions of a rare earth metal, called lanthanum, directly into cells as the vital first step in creating a new imaging technique designed to infuse EM with some much-needed color. After the holidays, when the lab returned to its usual hustle and bustle, Tsien handed off his project to Stephen Adams, a research scientist in his lab, thereby setting in motion a nearly 13-year quest to perfect the colorful new mode of EM.