Biopolymers and cell. 1999; 15 (6): 510 - 515

Stable torsional tension in DNA of Chironomus thummi polytene chromosomes

F. E. Kuzin, 1. E. Shilova, D. V. Bugreev, G. A. Nevinski, A. D. Gruzdev

Topological state of DNA in isolated polytene chromosomes of Chironomus thummi at the stage of the highest transcription activity has been determined by microfiuorometrical method. About 15 % °f chromosomal DNA stained with ElBr hevc been found to be under torsional stress. The value of the stress expressed as the relative twist difference is -II. I. It has been shown that domains of the stressed DNA contain transcriptionally active genes. Torsionully stressed DNA relaxes after addition of eiidogeneoits topoisoineruse I.