THE EFFECT OF IONIZING RADIATION ON ENZYMATIC ACTIVITY AS FOUND IN THE KREBS CYCLE IN TETRAHYMENA PYRIFORMIS AT DIFFERENT STAGES OF CELL DIVISION. Progress Report No. 4, February 1, 1962-February 1, 1963

Technical Report · Thu Oct 31 04:00:00 EST 1963

OSTI ID:4758335

Sullivan, W D

Mass cultures of Tetrahymena pyriformis GL were grown in a chemically defined medium and were subjected to cyclic heat shock to induce synchronous division. Tritiated thymidine (1.0 mu c/ml medium) was added during the last heat shock, 130 min before the onset of division. The addition of an increased amount of labeled thymidine (4.0 mu c/ml) during the 8 hr of heat treatment caused excessive labeling. Liquid emulsion autoradiograms were prepared from samples fixed at the following intervals after heat treatment: 10 min before the onset of division, at the onset of division, and at the next two 10-min intervals during cleavage. Incorporation of thymidine was determined by silver grain counts. No set pattern in the distribution of DNA in the daughter nuclei was observed. The concentration of labeled thymidine in the nuclei of heat-treated cells was low as compared to that found in the nuclei of normal cells. Cytoplasmic labeling was observed, and its concentration appeared to increase toward late division. The index of division (82.6%) in the control cells was higher than that of the experimental cells (53.7%), which suggested a possible block caused by the addition of non-essential thymidine to the medium. The occurrence of prominent Feulgen positive particles in the cytoplasm of heat- treated cells was observed. (auth)

• Research Organization: Boston Coll., Chestnut Hill, Mass.
• NSA Number: NSA-17-013979
• OSTI ID: 4758335
• Report Number(s): tid-17581
• Country of Publication: United States
• Language: English

Related Subjects

AMINO ACIDS
BIOCHEMISTRY
BIOLOGY AND MEDICINE
EMULSIONS
ENZYMES
MICROORGANISMS
NUCLEIC ACIDS
PROTOZOA
RADIATION EFFECTS
RADIOAUTOGRAPHY
REPRODUCTION
TETRAHYMENA PYRIFORMIS
THYMIDINE
TRACER TECHNIQUES
TRITIUM