File:Heritable-Change-Caused-by-Transient-Transcription-Errors-pgen.1003595.s007.ogv

English: Stochastic switching of one cell in a clonal population in the same environment. The growth of a single lacI A9 OFF cell in TMG maintenance media into a microcolony was followed in a microfluidics flow chamber by time-lapse microscopy. Each frame was, on average, taken about 60 minutes apart (some frames were lost due to loss of focus). The bright field frames are on the left, the GFP fluorescence frames are on the right and begin after the microcolony has become well established. The cell outlined in yellow is the cell that will change phenotype from OFF to ON, and the descendants of that cell will also manifest the ON phenotype. The cell outlined in red is the direct relative of the cell that switches ON, but that cell, and all the descendants of that cell remain OFF. All the GFP fluorescence frames, until the last frame, have 100 ms exposure times and the resulting images were over-exposed using the ColorSync Utility to observe the faint fluorescence signal. The last GFP fluorescence frame had a 3000 ms exposure time. The movie shows that an OFF cell growing in TMG maintenance media will be OFF, but has the possibility of switching ON, and once switched ON will initiate a cell lineage of ON cells, even though other surrounding cells in the same microcolony will be OFF.