Supporting Online Material

Cilia-Like Beating of Active Microtubule Bundles

Timothy Sanchez, David Welch, Daniela Nicastro, Zvonimir Dogic

Materials/Methods, Supporting Text, Tables, Figures, and/or References

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  • Materials and Methods
  • Figs. S1 to S3
  • References

Images, Video, and Other Other Media

Movie S1
Movie of a long active microtubule bundle observed with fluorescence microscopy(bundle length 130 μm). The freely beating bundle consists of thousands of microtubulesand is anchored at the edge of a 10-μm-high tape boundary. The 10 μm verticalconfinement of the chamber is much smaller than the length of the filament, causing thebeating pattern to be quasi-two-dimensional and stay in focus. Scale bar is 15μm.
Movie S2
Movie of a few active bundles of intermediate size (40-50 μm length) which are attachedto the edge of an air bubble. The movie illustrates three-dimensional beating patterns withbundles passing in and out of the focal plane. These comparatively smaller bundles beatmore quickly than the bundle shown in movie S1. Scale bar is 10μm.
Movie S3
A medium-sized active microtubule that exhibits sustained oscillations for over 2 1/2hours. A clear periodicity is present with a dominant frequency. Scale bar is 10 μm.
Movie S4
Dynamics of two microtubules observed with darkfield microscopy which are attached toeach other via a depletion interaction. The filaments are confined to a quasi 2D chamber.To suppress surface interactions the glass coverslide and slip are coated with polyacrylamidebrush. The microtubules slide past each other due to thermal forces. Theirpositions can be extracted and the calculated relative MSD shows that the microtubulesexhibit sub-diffusive behavior, indicating a viscoelastic coupling between the twofilaments. Scale bar is 5μm.
Movie S5
Multiple active bundles beating in close proximity. At sufficiently high density, activebundles synchronize their beating patterns, due to hydrodynamic and/or stericinteractions. This synchronization can persist over many beating cycles. Scale bar is 5μm.
Movie S6
An air bubble confined in a 10-μm-thick chamber, traps microtubules at the air-glassinterface. These microtubules nucleate assemblies of active bundles perpendicular to theedge of the bubble. At lower coating density, bundles beat asynchronously. The averagelength of bundles in this movie is around 10 μm. Scale bar is 20μm.
Movie S7
This video features the same air bubble as shown in Fig. 3A. At a high density of activebundles we observed the emergence of propagating density waves along the contour ofthe bubble. Scale bar is 20μm.
Movie S8
An air-bubble (with ~200 μm diameter) is coated with active microtubule bundles. Thelength of these bundles is, on average, 15 μm. Scale bar is 20μm.
Movie S9
Metachronal waves are capable of transporting debris in a preferred direction along thesurface of the bubble, mimicking the biological process of fluid transport along thesurface of a cell. Scale bar is 20μm.
Movie S10
Active microtubule bundles lodged beneath an air bubble in a 10 μm chamber. Thecomposite image sequence shows the bubble at two different z-positions: (left) at thecoverslip surface and (right) 5 μm off the surface, in the middle of the chamber. Bundlescan be seen in focus at both positions, indicating a three-dimensional beating pattern.This observation provides additional evidence that bundle beating is not due to surfacebound motors. Scale bar is 5μm.