[Replication and integration of the fragments of the new chains of the DNA of infusoria Tetrahymena pyriformis GL].

The size of the double-stranded molecules of DNA of the macronucleus of an infusoria Tetrahymena pyriformis GL in the G-1 period of the cell cycle is not less than 400 . 10(6) d. This was shown by alkaline and neutral isokinetic sucrose gradient centrifugation. At the S-period newly synthesized daughter strands of the DNA exist as the fragments of 10-30 . 10(6) daltons for a certain time (about 30 min). The sizes of the primer chains are not decreased. Thus, during the process of replication the primer chains are not fragmented, but the new ones are covalently bound. The synthesis of the new chains in the form of fragments and their subsequent assembly takes place during the S-period of Tetrahymena lasting for about 80 min. It is suggested that the found fragments correspond to the replicative units.