For a very long time, biallelically expressed genes have been assumed to have equal contributions from each allele. The inability to look at differences in terms of the transcriptional output at an allele-specific resolution has disallowed us to assess the relative contributions of each allele in such a biallelic context. The novel idea of studying hybrid genomes has paved the way for exploring transcriptional differences at an allelic resolution. Evidences from unpublished work in the lab performed on hybrid NPCs (Neural Progenitor Cells) strongly suggest the involvement of the ubiquitin ligase male-specific lethal 2 (MSL-2) in ensuring biallelic gene expression of dosage sensitive genes in mammals. However, in the context of the fruit fly Drosophila melanogaster, very little is known in the context of allele-specific regulation of gene expression. The broad goal of this project therefore, is to identify the possible involvement of either the MSL or the NSL complex members as allele-specific regulators of gene expression in Drosophila melanogaster and to then understand how and why they carry out such sophisticated transcriptional regulation.