Fig. 2.

Measuring transcriptional dynamics of eve stripe 2 formation using the MS2 system. (A) MS2 stem loops introduced in an eve stripe 2 reporter gene are bound by MS2 coat protein fused to GFP. (B) Sites of nascent transcript formation appear as green fluorescent puncta whose intensity reports on the number of actively transcribing RNAP molecules. Nuclei are visualized through a fusion of RFP to Histone. (C) Mean number of RNAP molecules actively transcribing the gene as a function of space and time (data averaged over 11 embryos).