Adult Pituitary Data1GFP fluorescence measured from single cells in adult pituitary tissue and subsequent modelling of transcription activity using a stochastic switch model.Adult Pituitary Data2GFP fluorescence measured from single cells in adult pituitary tissue and subsequent modelling of transcription activity using a stochastic switch model.Adult Pituitary Data3GFP fluorescence measured from single cells in adult pituitary tissue and subsequent modelling of transcription activity using a stochastic switch model.E18_5 Pituitary Data1GFP fluorescence measured from single cells in embryonic day18.5 pituitary tissue and subsequent modelling of transcription activity using a stochastic switch model.E18_5 Pituitary Data2GFP fluorescence measured from single cells in embryonic day18.5 pituitary tissue and subsequent modelling of transcription activity using a stochastic switch model.P1_5 Pituitary Data1GFP fluorescence measured from single cells in post-natal day1.5 pituitary tissue and subsequent modelling of transcription activity using a stochastic switch model.P1_5 Pituitary Data2GFP fluorescence measured from single cells in post-natal day1.5 pituitary tissue and subsequent modelling of transcription activity using a stochastic switch model.Adult Pituitary Trypsin Untreated Data1GFP fluorescence measured from single cells in adult pituitary tissue. Control sample to compare to Adult Pituitary Trypsin Treated Data1.Adult Pituitary Trypsin Treated Data1GFP fluorescence measured from single cells in adult pituitary tissue treated with trypsin for 2hrs prior to confocal imaging. Compare to Adult Pituitary Trypsin Untreated Data1.Adult Pituitary Trypsin Untreated Data2GFP fluorescence measured from single cells in adult pituitary tissue. Control sample to compare to Adult Pituitary Trypsin Treated Data2.Adult Pituitary Trypsin Treated Data2GFP fluorescence measured from single cells in adult pituitary tissue treated with trypsin for 2hrs prior to confocal imaging. Compare to Adult Pituitary Trypsin Untreated Data2.Adult Pituitary_Cx_AGA_Data1GFP fluorescence measured from single cells in adult pituitary tissue treated with 18alpha-glycyrrhetinic acid (20uM) for 2hrs prior to confocal imaging. Compare to Adult Pituitary Data2.Adult Pituitary_Cx_AGA_Data2GFP fluorescence measured from single cells in adult pituitary tissue treated with 18alpha-glycyrrhetinic acid (20uM) for 2hrs prior to confocal imaging. Compare to Adult Pituitary Data3.

Transcription at individual genes in single cells is often pulsatile and stochastic. A key question emerges regarding how this behaviour contributes to tissue phenotype, but it has been a challenge to quantitatively analyse this in living cells over time, as opposed to studying snap-shots of gene expression state. We have used imaging of reporter gene expression to track transcription in living pituitary tissue. We integrated live-cell imaging data with statistical modelling for quantitative real-time estimation of the timing of switching between transcriptional states across a whole tissue. Multiple levels of transcription rate were identified, indicating that gene expression is not a simple binary ‘on-off’ process. Immature tissue displayed shorter durations of high-expressing states than the adult. In adult pituitary tissue, direct cell contacts involving gap junctions allowed local spatial coordination of prolactin gene expression. Our findings identify how heterogeneous transcriptional dynamics of single cells may contribute to overall tissue behaviour.