Sugars light up the cells in this jaw of a 3-day-old zebrafish embryo and highlight a scientific first: labeling and tracking the movements of sugar chains called glycans in a living organism. Here, recently produced glycans (red) are on the cell surface while those made earlier in development (green) have migrated into the cells. In some areas, old and new glycans mingle (yellow). A better understanding of such traffic patterns could shed light on how organisms develop and may uncover markers for disease, such as cancer. Featured in the May 21, 2008 of Biomedical Beat.