FIG. 2.

Oct4 expression is detected in human embryonic stem cells (hESCs) by fluorescence resonance energy transfer (FRET) using confocal microscopy. Typical confocal micrographs of aggregated hESCs in suspension transfected with 6FAM (donor)- and 5ROX (acceptor)-labeled, Oct4-specific molecular beacons separately and in combination are shown. The same field is shown across each row, with each panel produced using the indicated excitation wavelength/detection filter combination. Individual beacons fluoresce at appropriate wavelengths (6FAM, upper left; 5ROX, middle middle), with absence of overlapping emissions (6FAM, middle left; 5ROX, upper middle). Only cells transfected with both beacons fluoresce at the acceptor's wavelength (610 nm) when excited within the donor's absorption spectrum (488 nm) (6FAM+5ROX, right lower). Scale bar: 100 μm. Color images available online at www.liebertonline.com/scd.