Lucplanfl n objective

Fluorescent signals of EGFP and mCherry were observed directly using reverse fluorescent microscopy IX81 (Olympus Corp., Japan) with either a 0.3 NA 10× UPlanFL N (Olympus) or a 0.6 NA 40× LUCPlanFL N objective (Olympus) through a blue and green filter, respectively. The images were recorded with a CCD camera (ROLERA-XR, QIMAGING) and LuminaVision software (MITANI Corp., Japan). The acquired images were analyzed using ImageJ ver. 1.45s (National Institutes of Health) software.
The cell behavior during the recovery culture was recorded by 10 min-interval time-lapse observations for up to 24 h using a BioStudio mini (Nikon Engineering Co., Ltd., Japan) placed in a CO2 incubator. We did not perform any fluorescent observation during the recovery culture so as to maintain the cell viability and not to reduce the fluorescent signals. At the endpoint of the time-lapse observation, a fluorescent observation was performed on the fused cell pairs or disconnected recipient cells.

After the experiments and 24 h incubation the cells were stained by the Hoechst 33342 Nuclear Staining Dye (Invitrogen) with a concentration of 1 μg/ml at 37ºC for 10 min. Nuclear Morphology of cell nuclei (chromatin condensation, presence of apoptotic bodies) was evaluated under an inverted fluorescence microscope IX81 Cell R equipped with a LUCPlanFLN objective (Olympus).