(IMAGE) University of Cologne Caption Densely packed DNA in female worms. DNA is blue, histone marker H3K9me2 is green, and the X-chromosone marker HIM-8 is red. Credit Siyao Wang, University of Cologne Usage Restrictions none License Original 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.