Ref ID : 3828
Guy Metenier; [Preuves Cinetiques de l'Existence d'une Periode de Competence pour la Transformation Microstome-Macrostome dans le Cycle Cellulaire de Tetrahymena paravorax]. J.Protozool. 25(3):326-334, 1978
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Seventy-seven percent of the microstomes of Tetrahymena paravorax taken from random samples of log-phase cultures transform directly into macrostomes in the presence of "stomatin". These macrostomes appear between 1.5 and 9 hr after addition of stomatin ("50% transformation point", ~2.5 hr). Competence for oral replacement is related to the position in the cell cycle. The highest percentages of transformation are observed in populations tested during the first half of the mean inter-fission period. Formation of macrostomes is more rapid when the initial age of the microstomes is nearer to the midpoint of the cell cycle ("competence point"). In the 2nd half of this cycle, the mean transformation time remains approximately constant, but the percentage of cells undergoing division is increasing. The "transition point" (50% divided cells) is found at the beginning of a terminal phase which accounts for 19-20% of the cell cycle. Transformation of anterior and posterior fission products is fairly asynchronous; in the majority of individual pairs, the opisthe is transformed before the proter. The daughter cells also divide asynchronously, the generation time of the proter being longer than that of the opisthe. The problem of acquisition of competence for phenotypic change is discussed in light of possible correlations with certain major processes of the cell cycle.