Novel DNA Repair Mechanism (IMAGE) Lomonosov Moscow State University Caption Estimated structure of the nucleosomal DNA loops, which are temporarily formed during transcription of chromatin containing intact DNA by RNA polymerase II (Pol II). In the presence of a single-strand DNA break, the loop structure likely changes, preventing rotation of the RNA polymerase along the DNA helix (orange arrow). Credit Nadezhda S. Gerasimova et al 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.