Accession Number : AD0640546

Title :   EFFECT OF X-RADIATION ON THE GROWTH AND DIVISION PROCESS OF TETRAHYMENA PYRIFORMIS,

Corporate Author : NAVAL RADIOLOGICAL DEFENSE LAB SAN FRANCISCO CALIF

Personal Author(s) : Schmid,P.

Report Date : 12 SEP 1966

Pagination or Media Count : 24

Abstract : Shortly after the beginning of x-irradiation a division block was imposed on exponentially replicating cells of Tetrahymena pyriformis and thereafter no cell division was observed for several hours. However, following x-irradiation Tetrahymena grew exponentially and increased in volume. The volume distribution of control and x-irradiated culture was lognormal. Furthermore, small cells originating from cells at the beginning of the division cycle grew at the same rate as large cells originating from cells which were close to division. This indicates that cell growth is independent of the cell division cycle to a significant extent. X-irradiation caused a temporary inhibition of the incorporation of tritiated thymidine into the DNA of cells, but DNA synthesis was resumed during irradiation, followed exponential kinetics even after x-irradiation was discontinued and stopped shortly before synchronous division. Thus, some biochemical adaptation of DNA synthetic mechanisms takes place during irradiation. (Author)

Descriptors :   (*CILIATA, CELL DIVISION), (*RADIATION EFFECTS, *CELL DIVISION), X RAYS, DEOXYRIBONUCLEIC ACIDS, BIOSYNTHESIS, CELLS(BIOLOGY), GROWTH(PHYSIOLOGY), THYMIDINES, TRITIATED COMPOUNDS

Subject Categories : Radiobiology

Distribution Statement : APPROVED FOR PUBLIC RELEASE