Approximately 1/2 of the macronucleoplasm of wild-type cells of Paramecium tetraurelia was transplanted into d4-84 mutant recipient homozygous for mutations nd3a (non-discharging trichocysts) and ts401 (temperature sensitive). After injection, 30% of surviving cells shifted from mutant to wild-type phenotype. Among the remaining cell lines 29% were unable to eject any trichocysts, and 41% discharged less than 10 of them per cell, when tested with picric acid. Observations were made through two successive vegetative fissions. These results showed that 30% of d4-84 cells contained foreign gene responsible for trichocyst discharge and produced cell lines of the wild-type phenotype, in which the expression as well as replication of this gene appeared normal.
M. Prajer, Department of Experimental Zoology, Institute of Systematics and Evolution of Animals, Polish Academy of Sciences, Slawkowska 17, 31-016 Krakow, Poland