A new monoclonal antibody inhibiting mating agglutination in Paramecium caudatum

Abstract

Mating reaction occurs between the cells of the odd and even complementary mating types in Paramecium caudatum. The molecules involved in this cell-to-cell sexual recognition called mating type substances are suggested to be proteins and exist on the ventral surface cilia of the cell. To obtain more varied epitopes, mating-reactive membrane vesicles reconstituted from odd mating type cilia of syngen 3 were used as antigen. A new monoclonal antibody XomO inhibiting the mating reactivity of both mating types was obtained. The unusual characteristic of XomO is the localization of the antigen, which particularly is recognized on basal portion, and not the whole length, of the ventral surface cilia. The antigen was suggested to be membrane protein and the detection of the antigen was correlated with the mating reactivity of the cells. These results suggest that the antigen of XomO is a substance involved in mating reaction under a dynamic-conformational change.