Restriction in the membrane diffusion over the dividing septum of Escherichia Coli cells measured by  Flourescence Recovery After Photobleaching

Abstract: This diploma thesis is a follow up work of a previous paper by Johan Strömqvist et. al. [1] In their article they presented a novel method on how to determine the Z-ring radius and the contraction in dividing Escherichia coli. This was done by fluorescent recovery after photobleaching (FRAP) measurements in the cytosol of E.coli cells transfected to express the Enhanced Green Fluorescent Protein (EGFP). The E.coli cell was irreversibly bleached on one side of an already visible invagination in the midcell, and then the fluorescence recovery was followed in time. Since the fluorescence recovery depends on the cross sectional area of the septum that information could be used to derive a mathematical expression to estimate the septal radius of the cell. In this thesis the goal was to, along with cytosolic recovery, examine the recovery after a bleaching pulse in the fluorescent labeled cell membrane. Furthermore it also set out to investigate how the cytosolic fluorescence recovery of EGFP was or could be correlated to the fluorescence recovery of dyes in the cell membranes of the E.coli.