MACRONUCLEAR EVENTS IN SYNCHRONOUSLY DIVIDING TETRAHYMENA PYRIFORMIS

Macronuclear Events in Synchronously Dividing Tetrahymena Pyriformis

The macronuclei of synchronously dividing mass cultures of Tetrahymena pyriformis (strain WH(6)) were examined with the electron microscope for changes during two division cycles. Samples were prepared at 30-minute intervals for a period of 8(1/2) hours which included the time required to induce synchrony by five heat shocks (4(1/2) hours). The interphase macronucleus contains peripheral, cresc...

Morphogenetic events in normal and synchronously dividing Tetrahymena.

SYNCHRONOUS cell-division has been induced in mass cultures of the small ciliated protozoan Tetrahymena pyriformis (Scherbaum & Zeuthen, 1954). While it is known that cells grow in a characteristic way during the synchronizing treatment the effect on the morphogenetic events associated with the cell cycle is not clear. Studies in ciliate morphogenesis generally have established the central posi...

Replication and Functions of Macronuclear Dna in Synchronously Growing Populations of Tetrahymena Pyriformis

Simultaneous Synthesis of Histone and Dna in Synchronously Dividing Tetrahymena Pyriformis

Histone and DNA syntheses have been studied in synchronously dividing Tetrahymena pyriformis GL. During the heat treatment necessary to synchronize cultures of this amicronucleate protozoan, the DNA content of the already polyploid macronucleus increases. When the cells begin synchronous division, their DNA content is reduced in a stepwise process which is closely paralleled by reduction of mac...

Replication of macronuclear DNA in the cytoplasm of Tetrahymena pyriformis.

Previous experiments showed that a synchronous population of Tetrahymena could divide even though DNA replication was blocked during the latter half of the preceding S-period byaddition of methotrexate plus uridine (M + U). Furthermore, it was found that the DNA fraction which was in replication at the time of inhibition became localized in the cytoplasm following elimination from the nucleus a...