84 BIOCHEMICAL SYSTEAAATICS 



the species studied contained agglutinins in their seeds, and a number 

 of the agglutinins showed some degree of specificity. This work will 

 be discussed in more detail later. 



The technique used in testing for plant agglutinins is rather 

 simple. Seeds are ground and extracted in saline, appropriately 

 diluted, and then incubated at room temperature with a suspension 

 of erythrocytes. The mixture is then examined for e\idence of agglu- 

 tination. Apparently the extracts are quite stable and may be re- 

 tained for months vsithout significant loss of acti\'ity. Makela, who 

 studied such pai-ameters as temperatui-e, salt content, and pH, re- 

 ported a surpiising tolerance for such an appai'ently specific reaction. 

 For example, agglutination occurred over a fairly wide concentration 

 of NaCl in the medium (though optimum results were obtained near 

 the "physiological" range) and over a pH range from 5 to 11. Despite 

 the simphcity of the technique there appears to be fairly good 

 reproducibihty, and some of the results are actually, in themselves, 

 validation of the method. For example. Schertz et al. (1960) 

 reported that a specific hemagglutinating substance. '"anti-A," from 

 the lima bean is inherited as a simple Mendelian dominant. The Fi of 

 a cross between one high-activity parent and one inactive parent 

 yielded seventy-two plants showing high activity, none showing no 

 activity. The F2 segregated essentially three active to one inactive. 

 Furthermore, Morgan and Watkins (1956) have utihzed specific plant 

 agglutinins to show that the blood group antigen of type AB individ- 

 uals is a unique molecule rather than a mixture of A and B substances. 



There is no certain knowledge of the chemical nature of the 

 plant agglutinins. Some investigators consider them to be muco- 

 proteins. Rigas et al. (1955) obtained a highly active mucoprotein 

 fraction which, when hydrolyzed, yielded an inactive polysaccharide 

 and a very active euglobulin. Presumably ehmination of the poly- 

 saccharide enhanced activity of the protein. However, he does 

 not beheve that the term "antibody" is entirely appropriate and in- 

 stead refers to the agglutinins as "lectins." Part of his objection to 

 the use of "antibody" Ues in the fact that their formation is not 

 ehcited as in the case of most animal antibodies. Some investigators 

 consider that the plant agglutinins do not react with the same re- 

 ceptors as do the typical antibodies. The question is not completely 

 settled, however. One argument in favor of a different mode of 

 specificity for the plant agglutinins is that the plant agglutinins are 

 neutralized in many cases by certain simple sugars while animal 

 agglutinins are not. Makela beheves that the plant agglutinins 

 accidently possess a configuration that is complementary to the 

 chemical grouping of the blood group substances. 



