Mutants of Paramecium Defective in Chemokinesis to Folate

Ten mutant lines of Paramecium tetraurelia defective in attraction to folate were isolated and examined. All mutants were normal in response to other attractants and repellents tested. One mutant was able to accumulate in folate given sufficient time. All mutations were recessive and behaved as single site Mendelian lesions. Complementation tests indicate that the mutants fall into three complementation groups. Mutants of Group 2 fall into two phenotypic classes and probably represent two alleles of the mutated fol² gene. Possible sites of the mutants'' blocks in chemoresponse are discussed.