Specific contact between mating structure membranes observed in conditional fusion-defective Chlamydomonas mutants.

Mating interactions between opposite mating type gametes in Chlamydomonas reinhardi can be conditionally manipulated by the use of mutants which control different stages in this process. Two independently isolated, sex-limited mutants (expressed only in mating type (-) (mt-] gam-10 and gam-11, have been shown to display a temperature-sensitive defect in mating. Gametes of these mutants can agglutinate, signal, and participate in a specific contact between their activated mating structures and the mating structures of wild-type mt+ gametes but are unable to fuse at the restrictive temperature. Studies of these mutants have resulted in a clear demonstration of this mating type-specific interaction between activated mating structures in this organism. This contact is trypsin-sensitive and therefore appears to involve protein. Both this interaction, and the defect in mating structure fusion, can be further analysed using these mutants.