Regensburg 2007 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 26: Poster Session II
BP 26.23: Poster
Donnerstag, 29. März 2007, 17:00–19:30, Poster B
Transfection Statistics from EGFP-Fluorescence Data — •Jan-Timm Kuhr1,2, Gerlinde Schwake3, Maria Pamela David3,4, Eduardo Mendoza3,4, Joachim Rädler3, and Erwin Frey1,2 — 1Arnold Sommerfeld Center for Theoretical Physics, Ludwig-Maximilians-Universität, München — 2Center for Nano Science, Ludwig-Maximilians-Universität, München — 3Physics Department, Ludwig-Maximilians-Universität, München — 4Marine Science Institute, University of the Philippines
We report on the stochastic nature of artificial gene transfer based on high content analysis of single cell fluorescence time courses. Using enhanced green fluorescent protein (EGFP), expression of typically 500-2000 individual cells was monitored. A wide range of expression values was found with typically 106−107 EGFP molecules per fluorescent cell.
For slowly degrading proteins theoretical analysis predicts that the protein distribution is a superpostion of Poissonians. For large expression factors these overlap only marginally, so the number of proteins per cell is determined by the plasmid content, i.e. variance in maximal expression arises from rare events of successful transfection. Since overlap is small, intrinsic fluctuations of expression can be neglected and the protein distributions is approximately discrete. Assuming a Poisson process for transfection, we find typically 1.3−1.4 plasmids per fluorescent cell and expression factors of ∼ 3·106. Hence, we identified variability in protein numbers to arise from stochasticity in the delivery process rather than from cell-to-cell variability in gene expression.