Figure 4

Dynamic instability of cytoskeletal filaments from eukaryotes and bacteria. (a) Dynamic instability of eukaryotic microtubules. Left: direct observation using dark-field microscopy of a microtubule undergoing dynamic instability. Middle: graph showing position of plus ends (top) and minus ends (bottom) for two dynamically unstable microtubules, with repeated cycles of growth and shrinkage. Numbered points correspond to individual video frames as labeled on the left (reprinted by permission from Macmillan Publishers Ltd: Nature 321:605–607, copyright 1986 [69]). Right, schematic diagram showing the connection between nucleotide hydrolysis and dynamic instability (Copyright 2008 from Molecular Biology of the Cell, 5th edition by Alberts et al. Reproduced by permission of Garland Science/Taylor & Francis LLC [41]). (b) Dynamic instability of bacterial ParM filaments. Left: fluorescence time-lapse images of a single ParM filament over time. Blue arrowhead shows position of initial filament appearance; red arrowheads mark the most extreme positions of the two tips. Video frames are separated in time by 5 s; scale bar is 2 μm. Right, traces of filament length over time for six different ParM filaments, showing a phase of growth followed by catastrophic shrinking. (From Garner EC, Campbell CS, Mullins RD: Dynamic instability in a DNA-segregating prokaryotic actin homolog. Science 2004, 306:1021–1025. Reprinted with permission from AAAS [54].)