Table 1.

Rates of F-pilus extension and retraction

Event	nm/sec
	N	Mean rate	Range	SD
Extension	14	39.5	27.2–52.9	8.2
Retraction	13	15.8	8.2–23.0	5.4

Rates were determined from movies of extension or retraction events using NIH ImageJ software or Zeiss LSM-5 imaging software. Zero times were taken as the appearance of a filament beyond the cell body (extension) or the first frame where an extended filament began to retract. Total extension and retraction lengths were about 1.5–5 μm (about 30–100 frames at 2 sec/frame). N = sample size; SD = standard deviation.