48 EGG AND SPERM SUBSTANCES 



to inactivate the receptors. Reducing agents do not destroy the 

 aggkitinating activity. 



Periodate oxidation destroys not only the aggkitinating action 

 (Immers and Vasseur, 1949) but also the receptors as shown by 

 inhibition tests ( Metz, 1954c ) . This action suggests that adjacent 

 hydroxyl groups of carbohydrate may be essential, but the action 

 of periodate is rather drastic, at least on long exposure ( Vasseur, 

 1952b) and may involve configurational changes in the molecule 

 which are largely responsible for the inactivation. Coupling with 

 diazo salts also inactivates the receptor groups (Metz, 1954c), 

 but diazo compounds react with such a variety of groups that 

 fmther study will be required to understand the inactivating ac- 

 tion of this agent. 



Several investigators (e.g., Vasseur, 1948; Monroy et at, 1954) 

 have suggested that sulfate groups are directly involved in the 

 combination of fertilizin with sperm antifertilizin. Several lines 

 of evidence support this view. Fertilizins low in sulfate {Bris- 

 sopsis lyrifem) fail to agglutinate sperm (Vasseur, 1948; Vasseur 

 and Carlsen, 1948 ) . Sulfate groups are hydrolyzed from fertilizin 

 at pH's that inactivate fertilizin (Vasseur, 1952a), but such inac- 

 tive fertilizin apparently has not been tested for univalence, and 

 blocking the basic groups of the sperm surface prevents agglu- 

 tination (Metz and Donovan, 1951) by fertilizin.* Finally, fer- 

 tilizin is adsorbed to positively charged resins (Monroy et al., 

 1954). It is also adsorbed to calcium carbonate, aluminum oxide, 

 charcoal, and kaolin ( Tyler and Fox, 1940 ) . 



A final observation that requires clarification concerns the role 

 of calcium in agglutination. In some forms this ion aids or is re- 

 quired for agglutination (Loeb, 1915; Vasseur, 1949a,b), but in 

 some others it is not essential (Dan, 1954b). 



* These experiments have been cited by Monroy et al. (1954) in support 

 of the above view. They involved the use of sperm killed with Bouin's fixa- 

 tive. Such sperm will agglutinate with homologous (Arbacia) fertilizin but 

 not with fertilizins from other species. This was originally interpreted to 

 mean that the fixation did not alter the sperm surface antifertilizin. How- 

 ever, subsequent study (Metz, unpublished) revealed that Arbacia fertilizin 

 will agglutinate Bouin's fixative-killed sperm of many species quite nonspe- 

 cifically. 



