•68 



SPERM, OVA, AND PREGNANCY 



I On 

 9 



ACTOMYOSIN 



ACTOSPERMOSIN 



O (D (D ® 



© (5) ©0 



© F-Actin 



(g) Spermosin 



@ Spermosin + F-Actin (ratio I2:i) 



@ Spermosin + F-Actin + AT P ( 4 23 x 10"" M) 



© Myosin 



© Myosin + F-Actin (ratio 2:1) 



@ Myosin + F-Actin + AT P (4 23 x 10"" M) 



Fk;. 13.18. Complex-formation and viscosity 

 change upon addition of adenosine triphosphate 

 (ATP) in system composed of contractile protein 

 extracted from bull sperm and actin from rabbit 

 muscle. The response of muscle actomyosin is 

 shown at the right for comparison. (From 8. A. 

 Burnasheva, Biokhimiia, 23, 558-563. 1958.) 



myosin. Further similarity is indicated by 

 the chiim that "spermosin" can combine 

 with actin, extracted from muscle, to form 

 an "actospermosin" complex (Burnasheva, 

 1958). This complex undergoes viscosity 

 changes similar to those shown by actomyo- 

 sin, upon the addition of ATP (Fig. 13.18). 

 It is to be noted that, thus far, physical 

 methods have not been applied to the study 

 of the protein isolated from sperm by these 

 investigators. Attempts to extract an actin- 

 like protein from bull sperm have thus 

 far proved unsuccessful. Whether the con- 

 tractile system of sperm is eventually re- 

 solved as a single component system, as 

 suggested by Burnasheva, or a double com- 

 ponent system as in muscle, remains for 

 further investigation to demonstrate. 



Although these extraction experiments 

 give strong evidence in favor of a myosin- 



like protein in sperm flagella, the picture 

 is far from complete. Rather striking dif- 

 ferences have been shown, for example, in 

 the response of fish sperm ATPase to cation 

 concentration when compared with the be- 

 havior of muscle ATPase (Tibbs, 1959). 

 Moreover, a comparison of structural details 

 of the sperm flagellum before and after 

 KCl-extraction procedures fails to indicate 

 the source of the extractable protein; in- 

 deed, very little change can be detected in 

 electron micrographs of mammalian sperm 

 subjected to such treatment (Bishop, 1961). 

 The motile mechanism of spermatozoa 

 has been investigated also by the prepara- 

 tion and reactivation of cell models, com- 

 parable to the glycerinated models of mus- 

 cle. Hoffmann-Berling (1954, 1955, 1959) 

 first accomplished this with sperm of the 

 locust, Tachijcines; as in the case of muscle 

 models, glycerol-extracted sperm were re- 

 activated by treatment with ATP at suit- 

 able concentration. This phenomenon has 

 since been demonstrated with sjierm of the 

 squid, Loligo, and of several species of 

 mammals (Bishop, 1958b, e; Bishop and 

 Hoffmann-Berling, 1959). The methods of 

 extraction, ATP concentrations, ionic re- 

 quirements, and response to sulfhydryl in- 

 hibitors are roughly similar to those appli- 

 cable to muscle models. The general nature 

 of the response to ATP, however, is strik- 

 ingly different in that the addition of the 

 nucleotide initiates flagellation which may 

 continue, in bull sperm for example, for as 

 long as 2 hours (Bishop and Hoffmann- 

 Berling, 1959). Apparently, contraction-re- 

 laxation cycles are induced in the models 

 which in frequency and amplitude are simi- 

 lar to those of normal fresh sperm. How- 

 ever, as a result of the complete loss of 

 permeability and co-ordination properties 

 of the flagellar models, wave propagation 

 along the flagellum fails to occur and for- 

 ward movement is insignificant. Among 

 other interesting features of these virtually 

 dead but ATP-reactivated sperm models is 

 the fact that they can be reversibly im- 

 mobilized by treatment with the Marsh- 

 Bendall (relaxing) factor, prepared from 

 rabbit muscle according to the method of 

 Portzehl (Bishop, 1958c). Moreover, the 

 models are capable of flagellation against 

 a force inijiosed by increasing the viscosity 



