Rawls Lickwar (IMAGE) Duke University Caption Fluorescence imaging of the zebrafish intestine reveals activity of ancient genetic regulatory elements. Nuclei of epithelial cells lining the intestine are shown in blue, and cells that have activated a regulatory element from the HES1 gene are shown in green. Credit Colin Lickwar 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.