CHARACTERISTIC OF THE CHROMATIN TYPE CORRESPONDING TO THIN «GREY» BANDS IN POLYTHENE CHROMOSOMES OF DROSOPHILA MELANOGASTER.

Recently, we developed a bioinformatic algorithm dividing drosophila genome into 4 types of chromatin which differ in protein composition. This allows us to propose a model of structural and functional organization of interphase chromosomes which postulates an existence of correlation between the chromatin types and morphological structures of polytene chromosomes. So, constantly and everywhere open chromatin type named «aquamarine» is characteristic of interbands, while the combinations of the other three types («lazurite», «malachite» and «ruby») form the bands. In this study, we characterized protein composition, genetic organization and morphological features of 39 «lazurite»-chromatin regions in polytene chromosomes. We found out that «lazurite»-chromatin usually form thin «grey» bands and more rarely — boundary portions of large bands. This type of chromatin contains coding parts and 3R-ends of genes and is enriched with proteins and histone modifications associated with active transcription at the stage of elongation. The expression patterns of these genes differ greatly depending on the type of chromatin in their 5R-regions.