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. 2013 Jun 13;8(6):e67165. doi: 10.1371/journal.pone.0067165

Figure 4. Investigating the effect of invasin on epithelial cells.

Figure 4

A) E. coli MG1655/pLacCherry (INV-) and its isogenic counterpart, E. coli MG1655/pINVCherry (INV+) were spotted on epithelial cells monolayer in the same plate using ATPS technique. The photo shows that the two spots are visible to the naked eye after 24 h of incubation. B) Microscopical analysis of the epithelial cell layer beneath the two spots (INV- and INV+). After washing out the two bacterial communities, the epithelial cells were stained with Calcein AM dye to compare the effects of the two bacterial spots on the viability of the underlying epithelial area. The photos were taken using an epifluorescence microscope at two different magnifications as shown. The white arrows point to the E. coli-invaded epithelial cells. Scale bar: 200 µm. C) Plot showing the integrity of the epithelial cells sheet underneath both spots. The fraction of the epithelial area fluorescing green underneath both spots were calculated using ImageJ program. The error bars represent the standard error of 4 spots for each case. Statistical analysis was performed using Student t-test. * p < 0.05.