Untangling DNA (IMAGE) John Innes Centre Caption John Innes Centre researchers found that the enzyme DNA topoisomerase VI (topo VI) performs a critical role in removing chromosome tangles that occur in the cell nucleus of plants Credit Shannon McKie Usage Restrictions No restrictions. License Public Domain 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.