270 C. J. BROKAW 



gella, which can be counted, the ATPase activity can be expressed on 

 a per flagellum basis, so that it can be more directly compared with 

 calculations of power requirements. The Michaelis-Menten constant 

 for ATP dephosphorylation by flagella is in the neighborhood of 

 10 -5 M, providing a further bit of evidence for biochemical similarity 

 between flagella and muscle. 



The flagella will also beat and liberate inorganic phosphate when 

 placed in solutions containing ADP. Chromatographic indentifica- 

 tion of ATP after incubating flagella with ADP demonstrated that 

 they possess an enzyme analogous to the myokinase of muscle, which 

 converts 2 ADP to ATP + AMP. 



Flagella from Chlamydomonas moewusii can also be reactivated 

 and have about as much ATPase activity per flagellum as Polytoma 

 flagella. However, flagella isolated from one of Lewin's "paralyzed" 

 mutants of Chlamydomonas could not be activated by ATP, and pos- 

 sessed only about one-third the ATPase activity found with normal 

 flagella (Brokaw, 1960). Not much can be made of this isolated re- 

 sult, but it does suggest another channel of approach to the problem 

 of flagellar motility. 



For observations of motility, the flagella suspensions are diluted 

 with 10 volumes of a solution containing ATP, 0.004M MgCl 2 , 

 0.05M KC1, 0.02M tris-thioglycolate buffer, pH 7.8, and 1% poly- 

 vinylpyrrolidinone. Motility can be observed at room temperatures, 

 but lasts much longer at 10-14°C. The movement usually stops 

 when the flagella become stuck down to the surface of the slide or 

 cover glass, but if this does not happen, the flagella may beat for up 

 to two hours. 



At first, most of the isolated flagella are motile, and swim regu- 

 larly through the suspending medium, basal end first. Forward pro- 

 gression is accompanied by rotation around a longitudinal axis, with 

 about one revolution for three to five beats. Many of the flagella be- 

 come attached to the slide or cover glass only at their basal end, so 

 that their beating can be observed under simpler conditions with- 

 out the complication of rotation. When observed with stroboscopic 

 illumination at a frequency slightly less than the frequency of beat, 

 the propagation of contractile waves along the flagella can be seen 

 clearly. The direction of wave propagation is always normal — from 

 base to tip, and the waves appear to be primarily planar. 



The statement that isolated flagella can swim around by them- 



