Interbands of Drosophila melanogaster polytene chromosomes contain matrix association regions

The DNA of three previously cloned interband regions (85D9/D10, 86B4/86, an d 61C7/C8) of Drosophila melanogaster polytene chromosomes has been tested for the presence of matrix association regions (MAR), using the in vitro ma trix-binding assay of Cockerill and Garrard. MARs were found in all three i nterband regions under study. These results are discussed in frames of a mo del postulating that interband regions of polytene chromosomes correspond t o the chromosomal DNA loop borders, which can be identified in interphase n uclei using biochemical approaches. (C) 1999 Wiley-Liss, Inc.