1. Actin Dynamics at the Living Cell Submembrane Imaged by Total Internal Reflection Fluorescence Photobleaching 
Susan E. Sund, Daniel Axelrod 
Biophysical Journal 
Volume 79, Issue 3, Pages (September 2000)
DOI: /S (00)
Copyright © 2000 The Biophysical Society Terms and Conditions

2. Figure 1
TIR versus EPI illumination on living BC3H1 cells injected with R-actin (a and b) or R-phalloidin (c– f). TIR illumination (a, c, and e) excites the fluorescence-marked actin selectively near the plasma membrane at cell-substrate contact regions. EPI illumination (b, d, and f) shown for the same cells excites the fluorescence-marked actin throughout the entire cell. Comparison of TIR versus EPI shows, for example, that the right side of the cell in c is not attached to the coverslip; a phase-contrast image (not shown) shows an adjacent nonfluorescent cell on the right, presumably intercolated into the substrate-proximal space under the fluorescent cell.
Biophysical Journal  , DOI: ( /S (00) )
Copyright © 2000 The Biophysical Society Terms and Conditions

3. Figure 2
Phase-contrast images of BC3H1 cells. (a) A field showing a rhodamine-actin-injected cell (marked by a star), with several other uninjected cells nearby. The injected cell was among those used for data acquisition (cell a of Fig. 5). (b) Another rhodamine-actin-injected cell used for data acquisition (cell e of Fig. 5).
Biophysical Journal  , DOI: ( /S (00) )
Copyright © 2000 The Biophysical Society Terms and Conditions

4. Figure 3
TIR optical setup and cell chamber. Our TIR optical setup uses two no. 2 coverslips and an inexpensive commercial 45–45-90° triangular prism (7-mm sides, refractive index=1.52). The top coverslip, to which the cells are adhered, is glued to the bottom of a drilled-out 35-mm plastic tissue culture dish with Sylgard 182 encapsulating resin (Exxex Group, Wood Dale, IL). The bottom coverslip is in optical contact with both the top coverslip above and the prism below through thin layers of immersion oil. For searching the cell culture in the horizontal plane with the standard microscope stage translators, the dish-coverslip configuration slides freely with respect to the prism, which is prepositioned below the stage by a three-dimensional translator attached to the microscope but otherwise held fixed. (Another possibility is to keep the lower coverslip fixed relative to the prism and allow only the upper coverslip to slide horizontally; this would minimize oil smearing when the sample is moved.) The laser beam enters the coverslips through the prism at a ∼75° incidence angle. Once trapped inside the coverslips, the beam totally internally reflects several times. The relatively thick double coverslip combination allows successive reflections to be well separated, but it is not so thick as to preclude the use of moderately short working distance objectives. The third or fourth reflection at the upper surface was used in these experiments. This setup requires an intermediate or long working distance water-immersion or air objective (an oil immersion lens would prevent TIR at the immersion-coverslip interface). (A Leitz achromat (50×, NA 1.00, free working distance 0.68mm, 160-mm tube length) was used here.) In contrast to other inverted microscope prism-based TIR configurations, this TIR setup has the advantages of 1) providing complete access to the cell from above and 2) presenting the sample at the immediate far side of a coverslip (rather than through an additional layer of medium beyond the coverslip), which reduces optical aberrations.
Biophysical Journal  , DOI: ( /S (00) )
Copyright © 2000 The Biophysical Society Terms and Conditions

5. Figure 4
Typical TIR/FRAP data with exponential fit (line) for a nondisrupted R-actin-labeled control cell. For this particular cell (shown in Fig. 5 a), the bleach fraction is 15%, the off-rate koff is 0.040±0.006s−1, and the mobile fraction α is 0.9.
Biophysical Journal  , DOI: ( /S (00) )
Copyright © 2000 The Biophysical Society Terms and Conditions

6. Figure 5
TIR prebleach intensity images of the seven R-actin-labeled cells used in nondisrupted control experiments (left) and the correspondingspatially resolved maps of 〈koff〉 (right), where each fit region is 4×4 pixels (1μm×1μm). Filamentous structures are clearly seen in the TIRF images of cells a, d, and e. The bar represents 20μm for all panels. The contrast scale for 〈koff〉 is dark gray=0, white=0.1s−1.
Biophysical Journal  , DOI: ( /S (00) )
Copyright © 2000 The Biophysical Society Terms and Conditions

7. Figure 6
Images of the spatially resolved kinetic parameters for a R-actin-labeled cell (cell a in Fig. 5). (a) Prebleach fluorescence intensity f(−) (no binning). (b) Off-rate koff (grayscale range 0–0.1s−1). (c) Mobile fraction α (grayscale range 0–1). For the kinetic parameters in b and c, the pixels are binned 5×5, corresponding to 1.25μm×1.25μm before the data are fit. The long white bar represents 20μm. The gray bar in the lower right corner of each panel represents the relevant dcorr lengths for this cell. The dotted lines in each panel show the orientations of the maximum gradient of a planar fit to the data for f(−), koff, and α, respectively.
Biophysical Journal  , DOI: ( /S (00) )
Copyright © 2000 The Biophysical Society Terms and Conditions

8. Figure 7
TIR/FRAP recoveries from the “fast” (■) and “slow” (△) ends of a particular R-actin-injected cell (cell a of Fig. 5), where the “fast” and “slow” ends are identified by a fit to Eq. 9. The bleach time is indicated by an arrow, and the smooth lines represent the computer fits to an inverted exponential. Note that the “slow” end appears to bleach less deeply than the fast end (see Appendix B). The noise in the recovery curves is due to both shot noise (random scatter) and possible small cell motions (infrequent step transitions).
Biophysical Journal  , DOI: ( /S (00) )
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9. Figure 8
Spatial autocorrelation functions G(r) for the average off-rate 〈koff〉 for the seven R-actin-injected cells depicted in Fig. 5.
Biophysical Journal  , DOI: ( /S (00) )
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10. Figure 9
Spatial map of the bleach fraction for an R-actin-injected cell (cell a of Fig. 5). White represents a bleach fraction of 0.3, and dark gray represents a bleach fraction of 0. The white bar represents 20μm. The gray bar, showing the calculated spatial autocorrelation distance, represents 3.8μm. The dotted line indicates the orientation of the maximum gradient of a planar fit (Eq. 9) to the data.
Biophysical Journal  , DOI: ( /S (00) )
Copyright © 2000 The Biophysical Society Terms and Conditions