Figure 6
Two characteristics of the mechanism for hyperosmotic induction of GS by intron 1. (a) The genomic position of intron 1 was changed from downstream (native context) to upstream (trans-positioned) relative to the transcription start site (TSS). The light green bars indicate the GS core promoter (GS-CP). The light blue color indicates the GS-OSRE1 element. (b) The corresponding reporter gene activity results are illustrated. (c,d) The effect of selective deletion of GS-OSRE1 from intron 1 (Intron 1▲GS-OSRE1) on reporter activity is shown. All reporter assays were carried out with reporter plasmid containing the GS-CP. Normalized F/R ratio expresses inducible Firefly luciferase activity versus constitutive Renilla luciferase activity. This ratio was measured for both isosmotic (315 mOsmol/kg) and hyperosmotic (650 mOsmol/kg) conditions and normalized by setting isosmotic controls to one. One-way ANOVA was performed to assess statistical significance of the data and calculate p values using the R Stats package software (https://www.R-project.org/). The number of asterisks indicates the statistical significance of the hyperosmotic induction (***p < 0.001; **p < 0.01, *p < 0.05, ns not significantly different).
