Fig. 1

Single-molecule fluorescence in situ hybridization data of Npas4 mRNA in primary neurons after membrane depolarization. Measurements are shown before the stimulus (uninduced), 5 min after KCl exposure, and an additional 10 and 20 min later after cells were returned to the conditioned medium (CM); see “Methods”. a Example of an image-processed cell at each time point. We show detected mRNAs (green circles) and active transcription sites (TSs; green squares) within the cell contour (yellow line) and nucleus (dashed yellow line). Neurons are post-mitotic and, thus, we observed up to two active gene loci per diploid cell. b For each condition, a histogram of the number of mRNA molecules binned by the number of TSs (dots, left y-axis). Smoothed histogram with bins of 20 mRNAs (bars, right y-axis). The total number of cells (n) per time sample is listed at the top. CM conditioned medium, TS transcription site