title: [Replicon size and rate of DNA replication in the macronucleus of Tetrahymena pyriformis].
abstract: The size of replication units (or replicons) measured in Tetrahymena pyriformis GL macronuclear DNA reaches 20--30 microns, according to the two independent methods: DNA fiber autoradiography, and alkaline isokinetic sucrose gradient centrifugation. The synthesis of new DNA fragments--replicons and their subsequent assembly are separated by time intervals (30 min). The rate of DNA synthesis for one fork averaged 0.6--0.7 microns/min. These data were obtained for cells of cultures being both in the expotential phase of growth, and those synchronized by starvation-refeeding. The generation time of T. pyriformis cells, calculated by the increase of the part of labeled nuclei, is almost 2 hours; the synthesis lasts 1 hour. Total amount of replication units in polyploid (polygenomic) Tetrahymena macronucleus is about 3000. Their initiation during S-period is presumably asynchronous.
mesh_terms: D000818:Animals; D002455:Cell Division; D004261:DNA Replication; D013769:Tetrahymena pyriformis / Q000166:cytology / Q000235:genetics*; D013997:Time Factors
vernacular_title: Razmer replikonov i skorost' replikatsii DNK makronukleusa infuzorii Tetrahymena pyriformis.