COMPREHENSIVE APPROACH TO MAPPING LATE-REPLICATING BANDS IN POLYTHENE CHROMOSOMES OF DROSOPHILA MELANOGASTER

Heterogeneity of chromatin structure underlies the banding pattern of Drosophila polythene chromosomes. Recently, a four-color model of chromatin has been proposed, with one chromatin type, aquamarine, largely corresponding to interbands (Zhimulev et al., 2014). In this model, most of the previously mapped regions of intercalary heterochromatin are represented by the ruby chromatin type. In the present report, we used the distal part of the chromosome arm 2R to show that all dense late-replicating bands in this region invariably encompass ruby chromatin type. We propose a comprehensive approach that combines cytology mapping data of the FlyBase-annotated genes, novel tools for predicting cytogenetic features of chromosomes based on their prothein composition and data on the sequence of replication in polythene chromosome bands. This approach allows to establish accurately the correspondence between reference late-replicating bands visible on cytology maps and the molecular map.