Fluorescent videomicroscopy

Fig. 4. Schematic of the single-molecule chromatin assembly experiments, (a) The fluorescence videomicroscopy experiments of Ladoux et al. [64] (for details see text), (b) The chromatin assembly experiments of Bennink et al. [65] a single >.-DNA molecule suspended between two micron-sized beads is being assembled with the help of Xenopus egg extract containing core histones and assembly factors (for details see text), (c) Example assembly curve at 1 pN (redrawn from Ref. [65]).

Vajkoczy P, Menger MD, Vollmar B, et al. Inhibition of tumor growth, angiogenesis, and microcirculation by the novel Flk-1 inhibitor SU5416 as assessed by intravital multi-fluorescence videomicroscopy. Neoplasia 1999 1(1) 31 11. 

Modern photomicrographic techniques allow one to observe the extended structure of a fluorescently labeled DNA strand as it travels through solution. Analyses of these shape changes give direct tests of models for electrophoresis and polymer dynamics. Early work on videomicroscopy of DNA electrophoresis in polymer solutions is due to Carlsson, et a/.(15) and Shi, et a/.(16). de Carmejane, et al. show three-dimensional imaging techniques that reduce ambiguities in simpler measurements( 17). 

Hydrodynamic interactions on a long length scale can be measured with two-point rheology, in which fluorescent or other beads are mixed with a polymer solution, and videomicroscopy is used to measure the Brownian displacements AR, of pairs of beads. The cross-correlations AR, ARy) determine the cross-diffusion tensors as a function of the separation between beads. For beads a fraction of a micron in size in polymer solutions and interbead distances out to 100 xm, measurements of Crocker, et al.(25), Gardel, et a/.(26), and Chen, et al.(21) agree the cross-diffusion tensor falls off with distance as /R, and has at least approximately the magnitude expected for the Oseen interaction in these viscous polymer... 

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