The organization of the eukaryotic genome in a nucleoprotein complex called chromatin has been studied intensively for decades. Nevertheless, the structure of chromatin, especially at its higher levels of organization is far from solved. Therefore, new methods proposing opportunities to look inside these structures from a different angle are searched. We are presenting our results with the implementation of a new approach to study higher-order chromatin organization. By a combination of the method of Comet assay with a nuclease attack of nuclear chromatin we were able to measure the size of chromatin loops. Additionally, we showed that DNA in nuclei, depleted of histone proteins is still organized in loops, although with size, different from that of native loops. These results present the Comet assay as a method for studying higher order chromatin structures.
Key words: chromatin, Comet assay, DNase I