Fig. 1: Monitoring transcriptional repression in vivo: the case of sna autoregulation.
a Schematic view of snaMS2 allele (above) and expression domain in the embryonic mesoderm (below, teal). The box indicates the restricted imaging area. b Maximum intensity Z-projection of representative nuclei showing MS2/MCP-eGFP-bound puncta and nuclei (His2A-mRFP) in sequential nuclear cycles. Images were taken from a heterozygous embryo expressing snaMS2 (Supplementary Movie 1). Scale bar represents 10 µm. c Instantaneous activation percentage (mean ± SEM) curves of ventral nuclei during the first 30 min of nc14. Time zero is from anaphase during nc13-nc14 mitosis. d Fluorescence intensity of actively transcribing nuclei (mean ± SEM) for snaMS2/+ nuclei during the first 30 min of nc14. Time zero is from anaphase during nc13-nc14 mitosis. e Sample single nucleus fluorescence traces in the first 30 min of nc14. Time zero is from anaphase during nc13-nc14 mitosis. f snaΔATG/ΔATG embryos demonstrate absence of Snail protein (green) and increased nascent transcription activity by smFISH relative to control embryos. Scale bar represents 10 μm. g Quantification of endogenous sna and snaΔATG transcription site intensity divided by background in early and late nuclear cycle 14 embryos via smFISH. Statistics: snaMS2/+: N = 6 embryos, n = 484 nuclei. smFISH: N = 3 snaΔATG/ΔATG embryos for early and late smFISH time points as determined by membrane invagination. Significance is indicated using a Kruskal-Wallis test (two-sided) with Dunn’s multiple comparisons.
