Fig. 1.

Characteristics of transgenes used in this study. a Schematic gene structure (top) of WT HBB including CMV promoter, Tet operator, pA signal, and exons (black blocks) as indicated. Total RNA-seq confirms Tet-inducible expression (bottom). b As a, for env. c, d Mutant versions of HBB and env, respectively. Point mutations in pA sites (“x”) and read-through transcription are indicated. Positions are relative to TSS; blue and orange shades correspond to WT and mutant versions, respectively; and light and dark shades correspond to 250 and 0 ng mL ⁻¹ Tet, respectively. Coverages by sequencing reads are shown. e Kernel density estimates of the flow-FISH single-cell readings corresponding to the abundances of HBB transcripts, WT (blue), mutant (orange) variants, and control (grey) cells, from replicate k=1, at different induction levels (Tet concentrations in unit of ng mL ⁻¹, shades of colours, as indicated on the left). Gene expression increases and saturates upon increasing Tet concentration, and mutant-cell expression is lower than the WT; a.u., arbitrary units; y-axes not to scale