Rapid Contraction of Hydra Tentacles Caused by Concanavalin Agglutinin, Lotus tetragonolobus Agglutinin and Ulex europeus Agglutinin

Abstract

The effects of lectins on hydra (Hydra japonica) were investi-gated in order to clarify the mechanics of its feeding response. Concanavalin agglutinin (Con A) induced rapid and prolonged tentacle contractions, but did not induce marked contractions of the body column. Lotus tetragonolobus agglutinin (Lotus A) and Ulex europeus agglutinin-1 (UEA-1) had effects similar to those of Con A, but rather induced the tentacles to make movements of a contracting-extending nature. Other lectins, including peanut agglutinin, soybean agglutinin, Dolichos biflorus agglutinin, wheat germ agglutinin, poke-weed mitogen, red kidney bean agglutinin and succinyl Con A did not cause contractions. Discontinuing the Con A, Lotus A or UEA-1 resulted in an extension of previously contracted tentacles. Lectin-induced contractions were rapid and reversible. The above results suggest that the binding by lectins to mannose-and fucose-residues of cell surfaces causes hydra tentacles to rapidly contract.