BIOMOLECULAR ASPECTS OF SPERMATOZOAN MOTILITY 203 



like on the basis of its nucleotide binding, while Tibbs (1957) re- 

 ported that the ATPase activity of the flagellum does not resemble 

 that of myosin. 



One characteristic feature of actomyosin is the capacity to undergo 

 intense shrinkage when ATP is added to it in the presence of suitable 

 concentrations of salts. The syneresis of actomyosin has received con- 

 siderable attention since the original experiments by Szent-Gyorgyi 

 (1942), and Weber (1957) has more recently reviewed the subject. 

 Myosin alone does not contract in the presence of ATP, but when 

 coprecipitated with actin the combined proteins shrink, but only 

 when, for example, KC1 and divalent cations are present. This effect 

 (and attendant viscosity changes) has been demonstrated in acto- 

 myosins from various sources, from Amoeba (Kriszat, 1950) and iso- 

 lated cell cytoplasm (Hoffmann-Berling, 1954) to many types of mus- 

 cle. Bishop (1958a) has reported the isolation from bull testes of pro- 

 teins contractile to ATP. 



PREPARATION OF GELS FROM FLAGELLA 



Very little protein could be extracted from fresh, damp fish sperm 

 flagella treated with 0.3M KC1 buffered to pH 6.8 with phosphates 

 (Guba-Straub solutions, see Guba and Straub, 1943, for origins). This 

 reagent might be expected to extract some actomyosin as well as 

 myosin from such finely divided material as flagella, since the extent 

 of comminution is important in deciding the nature of the extracted 

 proteins. (Weber and Portzehl (1952) comment on the factors in- 

 volved, for instance.) Even so, no appreciable precipitate was formed 

 when these salt solutions were diluted tenfold after several days ex- 

 traction. Occasionally, however, a few microscopic fibers were thrown 

 down on dilution, and dialysis of the diluted extract followed by 

 drying of the salt-free dialyzate gave residues too small to be ex- 

 amined. Addition of ATP to the extracting solution did not increase 

 the yield. 



On the other hand, extraction of flagella with 0.5-0.6M KC1 buff- 

 ered to pH 8-9 with sodium carbonate /bicarbonate (Weber-Edsall 

 solutions) resulted in the removal of some 25-40% of the weight of 

 the flagellum, depending on the length of extraction, presence of 

 ATP, temperature, etc. Since more protein could be extracted from 



