In situ digestion of Drosophila virilis polytene chromosomes by AluI and HaeIII restriction endonucleases

Abstract

Polytene chromosomes of Drosophila virilis were treated with AluI and HaeIII restriction endonucleases. Both enzymes were capable of extensively digesting chromosomal DNA, with the exception of some regions that contain repetitive DNAs. Moreover, a comparison was made between our data and the data already obtained with the same enzymes in D. melanogaster. On this basis, AluI digestion showed that the 5S RNA genes of D. virilis and D. melanogaster have different base composition, while digestion with HaeIII revealed resistance of the histone genes in D. virilis, contrary to what was previously found in D. melanogaster. Key words: restriction endonucleases, 5S RNA genes, histone genes, polytene chromosomes, Drosophila species.