(278d) Variability in the Dynamics of Individual Cells

Cell-to-cell variability in an asynchronous population of cells can be generally related to genetic differences, to different positions in the cell cycle, to the exposure of a heterogeneous environment, or to stochastic variations due to the low number of molecules in individual cells that cause noise in expression levels of specific proteins.

To evaluate the single cell variability in the dynamic response of individual cells that is not of genetic origin we have developed a novel flow cytometry instrument that is able to track individual, suspended cells in time. Individual cells can be repeatedly measured as they grow and express different proteins or as they respond to specific external stimuli of the growth environment.

We have followed the Gfp expression modulated by variation in growth temperature as well as the induction kinetics of Gfp in individual yeast and CHO cells over extended periods of time. The data indicate a large variability of the kinetic response of individual cells that is not apparent if only property distributions in entire cell populations are measured at discrete time points with conventional flow cytometry. Thus, the instrument permits evaluation of cell populations at a level of detail that can be only achieved to a certain degree by time lapse microscopy. The developed approach should be useful in the study of individual cell behavior and helpful in the rapid development of new drugs.