Figure 2.

Distribution of statoliths in characean rhizoids before lift off (−250 s) of the MAXUS-5 sounding rocket and during lateral centrifugation in microgravity (indicated in seconds after lift off). A, Series of micrographs of a representative rhizoid exhibiting symmetrical distribution of statoliths across the cell diameter before lift off. Centrifugal displacement of statoliths caused by the 0.14g acceleration in microgravity was first detectable at +429 s. Individual statoliths settled onto the cell flank toward the end of the microgravity phase (+692 s and +827 s). Arrows indicate the direction of gravitational and centrifugal forces. Diameter of rhizoid, 30 μm. B to D, Distribution of statolith frequency across the cell diameter of four rhizoids at indicated times of the rocket flight demonstrating that statoliths were displaced from a symmetrical arrangement before lift off (B) to an asymmetrical distribution during lateral centrifugation (C and D).