Figure 1.
Schematic representation of four antibiotic resistance gene expressing transposons based on PiggyBac backbone.
BlaR, blasticidin-resistance gene; zeoR, zeocin-resistance gene; puroR, puromycin resistance gene; hygroR, hygromycin resistance gene; EF1α, human elongation factor 1α promoter; ITR, terminal repeats; HS4, chicken β-globin hypersensitive site 4 insulator.
Figure 2.
Antibiotic resistance of mitomycin treated SNL DG5 feeder layer.
About 2×104 mitomycin C-treated SNL DG5 feeder cells were plated in each well of 96-well plate. The medium was added with different antibiotics concentrations and each concentration was in quadruplicate. Medium was changed every two days and the cells were cultured for 7 days. Survival rate is calculated by comparing to parallel-plated cells without antibiotics selection and expressed as a percentage.
Figure 3.
Stable transgene expression of established SNL DG5 feeder cell.
(A) The cells were seeded into 24-well plate and each was in duplicate. Antibiotics or antibiotics-free medium were added into each well for cell culture. The 2x antibiotics concentration was 80 µg/mL zeocin, 200 µg/mL hygromycin, 4 µg/mL puromycin and 6 µg/mL blasticidin respectively. The cell numbers were calculated every four days during each subculture and identical numbers of cells were seeded for continuous passaging. (B) MTT assay for comparison of PiggyBac mediated blasticidin resistance gene with original G418 resistance gene expression after long time cell culture.
Figure 4.
SNL DG5 feeder could maintain ES cell pluripotency.
(A) Cell morphology of NG2S and RGOC ES cell line grown on MEF and SNL DG5 feeder layers. The colonies are shown by phase contrast microscopy with 10x objective, and the scale bar is 100 µm. (B) Flow cytometry analysis of two ES cell lines (Nanog-EGFP, Rex1-EGFP) after three passages cultured on MEF and SNL DG5 feeder layers.
Figure 5.
Generation of ES cell reporter cell line with multiple fluorescence proteins co-expression.
(A) Schematic representation of inducible fluorescence protein expressing cassettes in the context of PiggyBac backbone. (B) Imaging of generated individual fluorescence reporter under different excitation light. Note that mAmetrine fluorescence was photographed under blue light thus has weak signal. The scale bar is 200 µm. (C) Genotyping analysis of generated ES cell reporter with five fluorescence proteins coexisted in single ES cell. (D) Flow analysis of generated No.12 multiple fluorescence protein stable ES cells. The thin red line on the left is the histogram without doxycline treatment as the negative control.
Figure 6.
Spectral unmixing and verification of multiple transgenes in single ES cell clone.
(A) Example of linear unmixing for cell lines with single mCherry and tdTomato fluorescence protein. (B) Linear unmixing of multiple fluorescence proteins based on ES cell lines with different individual fluorescence protein.
Figure 7.
Transposition efficiency of multiplex gene transfer based on PiggyBac system in mouse ESCs.
(A) AP staining for transfected stable ES cell clones using different combinations of antibiotics selections. Each dot represents a stable ES cell clone. (B) Transposition efficiency of PiggyBac mediated multiplex gene transfer. Data was based on two independent experiments.