256 



DAVID W. BISHOP 



Fig. 



ATP CONCENTRATION (M/l) 



1. Effect of ATP concentration on rate of flagellation of sperm 



models of sea urchin (Q) and starfish (#), in presence of 5 mM Mg+ + 

 and 10 mM histidine at pH 7.5. (After Kinoshita, 1958.) 



shows a Q 10 value approximating 2 over the range from 0° to 20°C 

 (Fig. 3). These data for insect sperm were obtained from cinephoto- 

 micrographic records (Hoffmann-Berling, 1955a). Mammalian sperm 

 models are inactivated at a temperature of about 27 °C; sperm models 

 of the invertebrate squid (Loligo) fail to respond above 12°C (Bishop, 

 1958a; cf. Matoltsy, 1950). 



The pH range for reactivation is fairly broad and could reflect the 

 unusual tolerance of many species of living sperm toward acid-alkali 

 changes (Mann, 1954; Bishop, 1961). Bull sperm models, for example, 

 respond to ATP over a range from pH 6.5 to 8.0 or greater, with an 

 optimum at 7.2 to 7.4. The frequency of beat of sea urchin and star- 

 fish spermatozoa is plotted against pH in Fig. 4; variation from 7.2 



