CHROMOSOME BREAKAGE PRODUCED BY TRITIUM-LABELED THYMIDINE IN TRADESCANTIA PALUDOSA

Journal Article · Mon Jun 01 00:00:00 EDT 1959 · Proc. Natl. Acad. Sci. U.S.

DOI:https://doi.org/10.1073/pnas.45.6.839· OSTI ID:4236865

Wimber, D E

The fragmentation of chromosomes in the root tips of Tradescantia paludosa as produced by tritium-labeled thymidine was measured. As many as 31 fragments per 100 cells occurred in roots grown for 4 to 8 hours in 1 or 2 mu c/ ml H/sup 3/-thymidine and then transferred a isothpefree solutions for further growth before collection. The highest fragment frequency could be correlated with the period during which the maximum amount of H/sup 3/thymidine was incorporated into the chromosomes. Up to 72 fragments per 100 cells at anaphase were demonstrated after continuous exposure of root tips to 1 mu / ml H/sup 3/- thymidine for times up to 56 hours. The mitotic index dropped sharply in roots that had been exposed to 1 mu c/ml of H/sup 3/-thymidine for periods over 8 hours. Cells that absorb large quantities of H/sup 3/-thymidine as indicated by autoradiographs are seemingly disturbed in their development and are delayed or prevented from entering mitosis. Autoradiographs of roots that had been exposed to 1 mu c/ml H/sup 3/-thymidine for 24 to 56 hours showed that the average grain count over dividing nuclei increased as the fragmentation appearing at anaphase increased. Approrimations of the dose delivered to the nuclei by the endogenous radiation from the tritium were made by two different methods; however, the esti mates showed poor agreement Confident calculations of the dose probably await the determinations of the efficiency of the beta rays in producing an autoradiograph. These findings would indicate that investigators utilizing tritiated substances should interpret their results with caution for the endogenous radiation delivered to a cell may be great enough to cause considerable chromosome breakage and presumably other forms of genetic damage as well as significant changes in cellular physiology. (auth)

• Research Organization: Brookhaven National Lab. (BNL), Upton, NY (United States)
• Sponsoring Organization: USDOE
• NSA Number: NSA-13-015898
• OSTI ID: 4236865
• Journal Information: Proc. Natl. Acad. Sci. U.S., Vol. Vol: 45; Other Information: Orig. Receipt Date: 31-DEC-59
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

BIOLOGY AND MEDICINE
AMINO ACIDS
BETA DECAY
BIOCHEMISTRY
CHROMOSOMES
ERRORS
GENETICS
LABELLED COMPOUNDS
MATHEMATICS
MEASURED VALUES
METABOLISM
MITOSIS
NUCLEIC ACIDS
PHYSIOLOGY
PLANT CELLS
PLANTS
QUANTITY RATIO
RADIATION DOSES
RADIATION INJURIES
RADIOAUTOGRAPHY
ROOTS
SOLUTIONS
THYMIDINE
TRADESCANTIA
TRITIUM
VARIATIONS