Flagellum length

Additional features of mutants If 1 and If 2 are listed below and will be described more fully in Section V which deals with studies on regeneration and flagellum length ... 

Flagellum length in growing cells is highly variable. 

Removal of nitrogen by transferring cells from growth medium to liquid NFM was found to cause a fairly rapid increase in mean flagellum length. From a value of 8.21 jam the mean length had increased to 10.50 jam after 4 hours and 11.77 jam after 24 hours. On other occasions mean lengths of 11.44 jam, 10.74 jam, and 10.93 jam were obtained after... 

Comparison of Maximum Flagellum Length in If 1 WITH Mean Flagellum Length in 32C... 

Fig. 33. Regeneration of flagella of long flagellum mutant If 1 in NFM. Flagellum length against time. Dotted circles, experiment 1 filled circles, experiment 2.

An isolated flagellum will continue to bend actively, indicating that this function is linked to its intrinsic structure. Treatment of cilia from the protozoan Tetra-hymena with the proteolytic enzyme trypsin selectively dissolves the nexin links and radial spokes but leaves unaffected the microtubules and dynein arms. If such a preparation is treated with a small amount of ATP, the loosened microtubule doublets slide against each other and through longitudinal overlap, extend for a distance that is up to nine times the original length of the cilium (Warner and Mitchell, 1981). 

It is informative to compare these dimensions with those of the smallest structures visible in cells for example, a bacterial flagellum is -13 nm in diameter and a cell membrane -8-10 nm in thickness. Bricks of the size of the 300-residue polypeptide could be used to assemble a bacterial flagellum or a eukaryotic microtubule. Helical polypeptides may extend through cell membranes and project on both sides, while a globular protein of the same chain length may be almost completely embedded in the membrane. 

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