Selection for conditional gametogenesis in Chlamydomonas reinhardi

A new technique is described for selection of temperature-sensitive mutants affecting gametogenesis in Chlamydomonas reinhardi. The first mutant found by this technique is characterized. Cells exhibiting the gam-1 phenotype are capable of sexual agglutination, but cannot form zygotes at the restrictive temperature. The mutation, however, has been expressed only in gametes of mating type (-). Cells of mating type (+) which carry this gene are able to engage in normal zygote formation. Temperature shift experiments and antibiotic studies have indicated that this gene is expressed within 6 hr after the onset of gametogenesis in liquid culture, and its product has a lifetime of about 4 hr at 35 degrees.