Analyses of the Change of Mating Type During Vegetative Reproduction in Paramecium caudatum
1960 年 35 巻 8 号 p. 213-221
詳細
1960 年 35 巻 8 号 p. 213-221
1. Some peculiar unstable caryonides, all individuals of which change their mating type during vegetative reproduction, were isolated from crosses of types XXIV and XXIII and from selfings of type XXIV in syngen 12 of Paramecium caudatum.
2. The change of mating type was reversible and affected by fission rate. The low fission rate favors the change to and the maintenance of type XXIII whereas the high fission rate favors the expression of type XXIV.
3. In ordinary selfing caryonides, the occurrence of selfing is due to the change of mating type during vegetative reproduction, which is also affected by fission rate. But in this case the change occurs only in a part of members of a caryonide.
4. The difference in the ratios of the changing individuals was clonal, though some slight differences were also observed in sister caryonides.
5. As to the patterns of inactivation of mating type substance by formalin, the unstable caryonide mentioned above was intermediate between types XXIV and XXIII.
6. In the light of these results, some considerations on the differentiation of mating types were presented.
