Correlation of Infectivity and Concanavalin A Agglutinability of Algae Exsymbiotic from Paramecium bursaria

SYNOPSIS. Eighteen strains of algae, including 17 exsymbiotic from Paramecium bursaria , were tested for infectivity for P. bursaria , syngen 2 aposymbiotes, and Concanavalin A (Con A) agglutinability. All 6 infective algal strains were relatively resistant to agglutination by Con A, suggesting that algal surface characteristics are correlated with infectivity. Among the noninfective strains, high and low agglutinability were about equally represented, indicating that the Con A titer alone is not a sufficient indicator of infectivity. It is suggested that noninfective algal strains are the progeny of mutations occurring within the endozoic population and fortuitously selected by the external culture medium.