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. Author manuscript; available in PMC: 2010 Apr 13.
Published in final edited form as: Science. 2007 May 25;316(5828):1191–1194. doi: 10.1126/science.1141967

Fig. 3. Imaging nonspecifically bound LacI.

Fig. 3

(A) Two fluorescence images with different exposure times and the corresponding DIC images of IPTG-induced E. coli cells. At 1000 ms, individual LacI-Venus appear as diffuse fluorescence background. At 10 ms they are clearly visible as nearly diffraction-limited spots. (B) Fluorescence spot size as a function of exposure time. The size is represented as the average variance of a 2D Gaussian function fit to images of fluorescence spots (±SEM, n~100). The same total excitation energy is used for different exposure time. The spots are measured before (−IPTG, •) and after (+IPTG, ▪) induction. The size converges to the width of the point spread function (full width at half maximum = 370 nm) below 5 ms.