Conjugation in tetrahymena pyriformis: The effect of polylysine, concanavalin a, and bivalent metals on the conjugation process

The polycation polylysine, at different degrees of polymerization, was found to cause a marked inhibition of the conjugation process. Inhibition of conjugation by polylysine was highly dependent on the molecular weight of the polymer. When polylysine of a mol wt of 1,250 (degree of polymerization = 6) was used, a concentration of 1.6 × 10^-5 M was required for a complete inhibition of conjugation, while only 2 × 10^-7 M of polylysine of a mol wt of 71,000 (degree of polymerization = 340) was needed for the same effect. Polyaspartic acid prevented the inhibition of conjugation by polylysine. Chelators of bivalent metals such as O-phenanthroline (10^-3 M), EDTA (10^-3 M), and EGTA (5 × 10^-3 M) strongly inhibit the conjugation process in Tetrahymena pyriformis. The inhibition was partially prevented when bivalent metals such as Zn⁺⁺ Fe⁺⁺ and Ca⁺⁺ were added together with the chelators. The lectin concanavalin A (25 µg/ml) completely prevented the conjugation process, while other lectins, such as phytohemagglutinin (500 µg/ml), soybean agglutinin (75 µg/ml) and wheat germ agglutinin (250 µg/ml) had no effect. Inhibition of conjugation by concanavalin A is completely reversible by 40 mM of α-methyl-D-mannoside.