CLONING AND ANALYSIS OF DNA FROM 85D9 D10 AND 86B4/B6 INTERBAND REGIONS OF DROSOPHILA-MELANOGASTER POLYTENE CHROMOSOMES/

A recently developed complex approach based on electron microscopic ma pping of the P element inserts in the interband regions of Drosophila polytene chromosomes was used for the cloning and sequencing of DNA fr om the 85D9/D10 and 86B4/B6 interband regions. The in situ hybridizati on technique showed that these DNA fragments belonged to the fraction of unique sequences of the Drosophila genome. Comparison of the cloned sequences with the earlier cloned 61C7/C8 interband region was carrie d out. Our findings indicated that these clones were represented by AT -rich sequences (over 80% AT) interspersed with segments with a random nucleotide composition. The interband regions were shown to contain l arge amounts of polypurine, polypyrimidine and purine-pyrimidine stret ches. This structural organization is typical of DNA sequences that ar e able to form noncanonical secondary structures and is similar to tha t of matrix-attached DMA regions. Cloned interband DNA regions were sh own to contain short open reading frames with an unknown functional ac tivity.