Sex-specific binding and inactivation of agglutination factor in Chlamydomonas eugametos

Gametes of opposite mating type (mt ⁺ and mt ^-) of the green alga Chlamydomonas eugametos agglutinate via their flagella as a prelude to sexual fusion. To quantitate sexual agglutination, an in vitro assay has been developed using ³⁵S-labeled flagella and the isolated mt ^-agglutination factor. It is shown that not only isolated flagella, but also the mt ^-agglutination factor rapidly bind to the flagella of intact gametes of the opposite mating type. This confirms the role of the mt ^-agglutination factor in determining the sexual agglutinability of mt ^-gametes. As a function of binding, the agglutinative power of the flagella of both mating types is destroyed by a temperature-sensitive process. Likewise, the mt ^-agglutination factor can be completely inactivated.Abbreviations Mt ^+/- mating type plus or minus - PAS periodic-acid Schiff-reagent - Hepes 4-(2-hydroxyethyl)-1-piperazineethansulfonic acid - HMC buffer Hepes buffer (10 mM. pH 7.2, containing 1 mM MgCl₂ and 1 mM CaCl₂)