Analysis of DNA replication parameters in isolated organs of drosophila melanogaster by molecular combing

Methods of DNA physical mapping and the direct visualization of the replication and transcription in specific genome regions play a crucial role in the study of structural and functional organization of eukaryotic genomes. Since DNA strands in cells are organized into high-fold structure and structurally present as highly compacted chromosomes, the majority of methods at the chromosome level are of low-resolution. An approach to increasing the resolution and accuracy is molecular combing. The method is based on the process of stretching and alignment of DNA molecules that are covalently attached with one of the ends to the coverglass surface. In this article, we describe the major methodological steps of molecular combing and their adaptation to study the parameters of DNA replication in polyploid and diploid tissues of drosophila larvae.