Development of an Approach for Parasegment-Specific Labeling of Nuclei in Drosophila melanogaster Embryos

Effective approaches for selecting nuclei in which a gene of interest is in an active state are necessary for studying spatial organization and gene expression regulation. In this work, a novel two-component genetic system was created for the parasegment-specific labeling of nuclei in which the regulatory domain iab-5, which stimulates the homeotic gene Abd-B, is active. The system is based on the integration of a transgene expressing the yeast GAL4 activator under the control of the minimal hsp70 gene promoter into the iab-5 domain, near the early embryonic enhancer. As a result, the iab-5 enhancer induces specific expression of GAL4, which strongly amplifies the expression of the mScarlet fluorescent protein, allowing for the efficient selection of labeled nuclei in which the iab-5 domain is activated. This approach can be used for the selection of target nuclei in which any regulatory element or gene of interest is in an active or repressed state.