Visualizing Transcription Dynamics in Drosophila

Embryos were obtained from crosses between males carrying MS2 reporters and females carrying the maternally expressed MCP-NoNLS-eGFP (Garcia et al., 2013 (link)) and His2Av-mRFP (Bloomington # 23561) transgenes both on the second chromosome. Embryos with reduced activity of Bcd were obtained from females which were in addition heterozygotes for the bcdΔ molecular null allele or for the bcd^E1 allele (bcd⁶). Unless otherwise specified, all MS2 reporters were inserted at the vk33 docking site (Bloomington # 9750) via φC31-mediated integration system (Venken et al., 2006 (link)) by BestGene. The site of insertion was chosen because the transcription dynamics of the original hb-P2 reporter (Lucas et al., 2018 (link)) inserted at this site was indistinguishable from the transcription dynamics of two randomly inserted siblings (Figure 1—figure supplement 1, panels A-C). All fly stocks were maintained at 25°C.