Primer Sample (IMAGE) Duke University Caption Secret primers, as the one shown in this photo, could be used to reveal genetic 'barcodes' added to DNA samples taken in the field to ensure they arrived at the laboratory unaltered. Credit Mohamed Ibrahim, Duke University 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.