Polytene chromosome interband DNA is organized into nucleosomes

The molecular basis that underlies the maintenance of polytene chromosome b anding pattern remains unclear. To test the possibility that the decondense d state of interbands is provoked by the absence of nucleosomes, we have su bjected chromatin from the previously defined 61C7/C8 interband to digestio n with micrococcal nuclease. We have demonstrated that interband DNA forms nucleosomes both in salivary glands and in the bulk of larval tissues. This finding strongly suggests that the difference in compaction between DNA in polytene chromosome bands and interbands results from differences that app ear at the higher levels of chromatin organization.