Haemagglutinins in six species of freshwater crayfish

The sera of six species of freshwater crayfish ( Austropotamobius pallipes, Astacus astacus, Astacus leptodactylus, Pacifastacus leniusculus, Procambarus clarkii and Cherax quadricarinatus) were shown to contain haemagglutinins by using vertebrate erythrocytes as agglutinogens. They were found in the serum, heart, abdomen and claw muscle as well as the hepatopancreas and the reproductive tissues. Inhibition assays showed that the serum haemagglutinins could be inhibited by carbohydrates or glycoconjugates and that the serum and all other tissue haemagglutinins, except those of the hepatopancreas, were inhibited by the same combinations of carbohydrates. An analysis of the chemical and physical properties of sera from five species ( C. quadricarinatus was excluded due to the low titres) showed that the haemagglutinins were all nondialysable, heat-labile glycoproteins, which were susceptible to the action of pronase E. Trypsin, urea and 2-mercaptoethanol, however, were variable in their action between species as was the dependency on divalent cations to maintain the agglutination function. Cross-adsorption experiments suggested that the haemagglutinins may react with similar determinants on the surfaces of different erythrocytes. Together these comparative physicochemical characterizations suggest that these molecules were not the same in all five species of crayfish.