Function of the male-gamete-specific fusion protein HAP2 in a seven-sexed ciliate.

摘要: Summary HAP2, a male-gamete-specific protein conserved across vast evolutionary distances, has garnered considerable attention as potential membrane fusogen required for fertilization in taxa ranging from protozoa and green algae to flowering plants invertebrate animals [1–6]. However, its presence Tetrahymena thermophila , ciliated protozoan with seven sexes or mating types that bypasses the production of male gametes, raises interesting questions regarding origins gamete-specific functions sexually dimorphic species. Here we show HAP2 is expressed all T. thermophila fertility only blocked when gene deleted both cells pair. deletion strains complementary can recognize one another form pairs; however, pair stability compromised pore formation at nuclear exchange junction blocked. The absence consistent previous studies suggesting role gamete fusion other systems. We propose model which each several hundred pores established conjugation represents equivalent male/female interface, driven on sides by HAP2. Such supports idea many disparate sperm egg were shared "isogametes" early eukaryotes became partitioned either female sex later evolution.