Gene Specificity of Suppression of Transgene-Mediated Insertional Transcriptional Activation by the Chicken HS4 Insulator
Figure 4
Orientation-dependent silencing of β-EGFP expression in the presence of the G8 repeats.
A: Dot-plots illustrating EGFP expression of representative clones one or three months after RMCE. X-axis: forward-scatter; y-axis: FL-1 (EGFP) fluorescence. The horizontal line represents the level of auto-fluorescence of non-tranfected control MEL cells. Presence of one copy of G8 3′ of EGFP, or of two flanking copies of G8 caused silencing of the transgene in the N but not in the P orientation. B: Q-RT-PCR analysis of EGFP expression demonstrating that the silencing induced by the G8 repeats occurs at the mRNA level.