[Correlation on a cellular level of gene transcriptional silencing and heterochromatin compartment dragging in case of PEV-producing eu-heterochromatin rearrangement in Drosophila melanogaster].

Eu-heterochromatic rearrangements transfer genes into the heterochromatin and cause their variegated inactivation (PEV). Genes affected by PEV often demonstrate association with heterochromatic nuclear compartment (a distinct area composed of heterochromatin sequences like satellite DNA and enriched in specific chromatin proteins e.g. HP1). Here, we investigate the nuclear localization and the expression levels of the genes subjected to PEV caused by chromosome inversion, In(2)A4. We demonstrate that the degree of PEV-caused gene inactivation depends on a developmental stage, and the maximum of repression corresponds to the gene expression activation period. In the case of In(2)A4 rearrangement we detect the dragging of affected euchromatic region into heterochromatic nuclear compartment and the increase in HP1 occupancy in this region. We developed a protocol of simultaneous RNA-DNA-protein staining to demonstrate firstly in a single cell a strong correlation between transcriptional activity of affected gene and its distance from chromosome 2 satellite DNA.