Microscopy image data containing fluorescently labeled gene loci, recruited RNA polymerase II, and elongating RNA polymerase II. This data set is for the gene iscub and is obtained from fixed zebrafish embryos, collected at the sphere stage of development. Embryos were treated for 30 minutes prior to collection with control media, flavopiridol (10 µM, 30 minutes), JQ-1 (10 µM, 30 minutes), or hexanediol (3% weight/volume, 5 minutes). Data were recorded using an instant-SIM microscope (iSIM, VisiTech UK) with a 100X TIRF oil immersion objective (Nikon, NA 1.49, CFI SR HP Apo TIRF 100XAC Oil). Two samples were prepared per inhibitor condition, and images were recorded from 3-4 embryos per sample, as indicated in the file names. The image data are in the ND2 format (Nikon proprietary) and can be imported using the BioFormats importer (Open Microscopy Environment).

Additional data that did not fit the file size limit are available at this address: https://doi.org/10.5281/zenodo.7437616