Figure 2.

Inhibitory effect of DP178 peptide detected by the three-color assay. TF228 cells were labeled with the cytosolic probe CMAC, and SupT1 with both the lipophilic probe DiI and the cytosolic dye calcein, and cocultured at 37°C for 2 h. Images were acquired as described in the text with an Olympus IX70 microscope. The images are acquired in bright field and in fluorescence, using the “DAPI” (CMAC), “rhodamine” (DiI), and “FITC” (Calcein) optical filter cubes, respectively. The characteristics of the filter cubes are listed in the Materials and Methods section. The figure shows fields of a representative experiment. (a) 50 ng/ml peptide. Two cells in contact are presented in bright field. The one in the left (TF228) was originally labeled with CMAC; the cell in the right (SupT1) was labeled with DiI in the membrane and calcein in the cytoplasm. The DiI image shows the transfer of the lipophilic probe from the upper cell to the lower while the hydrophilic probes have not moved. (b) No peptide. This cell has the three dyes indicating complete fusion.