Files in this Data Supplement:

• Supplemental Figure 1 -

  Fig. S1. Photoelectric recordings of ciliary beat are influenced by the location of the diode with respect to the image of beating cilia. (A) Schematic representation of the movement of a single cilium during a beat cycle. Although recordings were generally performed with the photodiode lying in the beat plane, this schematic shows a more oblique orientation to illustrate ciliary movements. During the effective stroke (red, ES) the cilium pivots stiffly around its base. During the recovery stroke (blue, RS), the cilium bends along its length and thereby returns to its resting position. (B) Photodiode positioned at a distal position records cilia only during the effective stroke. (C) Trace obtained at medial position records cilia during effective stroke (1, red), recovery stroke (2, blue) and during the rest phase (3, black) of the beat cycle. (D) Trace obtained at basal position shows high frequency activity of multiple cilia, including both pre-oral and post-oral bands, in different phases. Scale bar, 150, ms.

  Immobilized vela were generally oriented with either their frontal or posterior side facing the diode. Thus, cilia either beat towards or away from the diode and the extended cilia during effective strokes could clearly be seen as the peaks of metachronal waves. Recordings from post-oral cilia could only be performed when the posterior side of the velum faced the photodiode, since the post-oral band is located on this side of the velum.

  Positioning the diode on the image near the tips of the extended cilia (Fig. S1A) produced recordings with regular, sharp upward deflections that were separated by periods of relatively flat baseline (Fig. S1B). These upward deflections appeared to represent the shadows cast by erect cilia during their effective strokes. Recordings around the mid-lengths of the cilia (Fig. S1C), produced traces with the three distinct phases expected from previous descriptions of ciliary movements during a normal beat cycle (see Blake and Sleigh, 1974). Phase 1, always a large upward deflection, represented the effective stroke, during which stiff cilia cast a full, brief shadow onto the diode. The following phase (Phase 2), generally a wider and smaller amplitude upward deflection corresponded to the recovery stroke, in which bent cilia passed the diode for much of their lengths while casting their partial shadows. Phase 3, a short downward deflection toward baseline activity, represented a rest phase that normally separates successive beat cycles. Finally (Fig. S1D), when the photodiode was moved even closer to base of the cilia, irregular, high frequency traces were recorded, which presumably reflected the combined movements of both pre-oral and post-oral cilia moving through both effective and recovery strokes. The activities of shorter and more rapidly beating post-oral cilia (see below) may have also contributed to these recordings. In subsequent analyses of ciliary beat frequencies (CBF), recordings were obtained from mid-length regions of the pre-oral cilia.

  References

  Blake, J. R. and Sleigh, M. A. (1974). Mechanics of ciliary locomotion. Biol. Rev. Camb. Philos. Soc. 49, 85-125.