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EN
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.
EN
The onset of autogamy is preceded by a 'critical fission', final, irreversible commitment to autogamy occurring at the G1 phase, about 1 h after this fission. In order to ascertain whether cytoplasm from cells committed to autogamy can induce this process in young cells, cytoplasm from P. tetraurelia cells, being 1,5 to 2 h after the critical fission, was transplanted into cells immature for autogamy. None of the 92 experimental cells entered autogamy, while most of the donor sister cells were autogamous. This result indicates that cytoplasm at this stage is ineffective in inducing autogamy, which may be caused either by the lack of the responsible component, or by too small a volume of transplanted cytoplasm, insufficient to overrule the action of autogamous immaturity factor/s. or/s.
EN
This paper reviews recent investigations on nuclear and cytoplasmic factors affecting the interautogamous interval. It is concluded that although its length is essentially determined by the macronucleus, cytoplasmic factors also play an important role in its regulation. Apart from immaturin, the authors summarize observations indicating the possible presence of an 'autogamous immaturity factor' and 'autogamy accelerating factor'.
EN
Duration of the interautogamous interval (IAI) was studied in wild and mutant stocks of Paramecium tetraurelia. The investigations revealed slight but statistically significant differences in IAI duration in complementary mating types of some stocks of P. tetraurelia. A certain range of variability characterized the duration of this period in particular stocks. The greatest variability observed in mutant stock d4-108 may result from abnormal, unequal macronuclear divisions frequent in these mutant cells. In none of the investigated stocks is parental age of relatively young, mature for autogamy cells related to the IAI duration in progeny generation.
EN
Sexual immaturity in the Paramecium aurelia species complex is genetically controlled, its duratin being expressed by the number of cell divisions between successive conjugations or autogamies.During post-conjugational immaturity mating eractivity is regulated by a cytoplasmic protein - immaturin.The present study revealed that cytoplasm containing immaturin of Paramecium primaurellia injected into preautogampus cells of Paramecium tetraurelia does not inhibit the latter in entering autogamy.This results suggests that immaturin is inefective in the inhibition of autogamy.
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