Leaky expression of the Tet-On 3G and Tet-On 3G-tTS systems.

(A) A schematic diagram of vectors. Plasmid 3 (p3): the kid gene expression was controlled by TRE3G promoter control, and the Tet-On 3G transcriptional activator protein was controlled by the Opie2 promoter. Plasmid 4 (p4): Added the tTS gene expression cassette to the p3 plasmid. (B) Count of red fluorescence-positive cells in (C). Means and standard deviation were calculated from three representative pictures (one from each of three independent biological replicates). Values followed by different letters with a column are significantly different at P < 0.05 according to one-way ANOVA. (C) Sf9 cells were transfected with plasmid p1, p2, p3, or p4, and 6 h later, doxycycline (50ng/μL) was added to the medium as indicated. The fluorescence expression and status of the insect cells were observed under a microscope at 48 h after transfection. The circled cells are fragmented and dead cells. Scale bar = 50 μm.