Mutants of Chlamydomonas moewusii with Impaired Motility

SUMMARY: A method is described for obtaining mutants of Chlamydomonas moewusii with impaired motility. Thirteen distinct mutants with paralysed flagella were isolated, and eleven of these were obtained in both mating types by crossing with wild type. No sexual activity was elicited in M. 1060 (minus). No allelism was detected among the remaining twelve mutants. In M. 1002 plus, the locus for paralysis appears to be very closely linked with that of mating type. In certain mutants, paralysed plus gametes, when paired with wild-type minus, recovered motility after some hours. Recovery is attributed to the passage of motility factors across the protoplasmic bridge linking the paired gametes. Paralysed minus cells may act as donors of such factors when paired with paralysed plus cells of an unlike mutant strain. The pairs formed by mating genetically dissimilar gametes are considered as heterokaryons, which can be used to provide information on the identity or non-identity of genes associated with paralysis. The role of a number of transmissible factors in normal flagellar activity is thereby implicated.