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Title: Detection of induced DNA strand breaks with improved sensitivity in human cells

Abstract

When mixtures of two cell populations labeled with different radionuclides are tested with DNA unwinding technique, an accurate comparison with regard to DNA strand breaks can be made. In mixtures of irradiated and control cells, effects were detected by this technique down to a dose of 1 rad. This corresponds to 10 to 20 DNA single-strand breaks per cell, or less than one break per chromosome.

Authors:
Publication Date:
Research Org.:
Univ. of Uppsala, Sweden
OSTI Identifier:
5463802
Resource Type:
Journal Article
Resource Relation:
Journal Name: Radiat. Res.; (United States); Journal Volume: 81:3
Country of Publication:
United States
Language:
English
Subject:
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.; 59 BASIC BIOLOGICAL SCIENCES; COBALT 60; GENETIC RADIATION EFFECTS; DNA; RADIOSENSITIVITY; GAMMA RADIATION; STRAND BREAKS; RADIOINDUCTION; CELL CULTURES; CHROMOSOMES; DOSE-RESPONSE RELATIONSHIPS; EXPERIMENTAL DATA; HELA CELLS; ISOLATED VALUES; ISOTOPE APPLICATIONS; POPULATIONS; THYMIDINE; TRITIUM; AZINES; BETA DECAY RADIOISOTOPES; BETA-MINUS DECAY RADIOISOTOPES; BIOLOGICAL EFFECTS; BIOLOGICAL RADIATION EFFECTS; COBALT ISOTOPES; DATA; DATA FORMS; ELECTROMAGNETIC RADIATION; GENETIC EFFECTS; HETEROCYCLIC COMPOUNDS; HYDROGEN ISOTOPES; INFORMATION; INTERMEDIATE MASS NUCLEI; INTERNAL CONVERSION RADIOISOTOPES; IONIZING RADIATIONS; ISOMERIC TRANSITION ISOTOPES; ISOTOPES; LIGHT NUCLEI; MINUTES LIVING RADIOISOTOPES; NUCLEI; NUCLEIC ACIDS; NUCLEOSIDES; NUCLEOTIDES; NUMERICAL DATA; ODD-EVEN NUCLEI; ODD-ODD NUCLEI; ORGANIC COMPOUNDS; ORGANIC NITROGEN COMPOUNDS; PYRIMIDINES; RADIATION EFFECTS; RADIATIONS; RADIOISOTOPES; RIBOSIDES; YEARS LIVING RADIOISOTOPES; 560121* - Radiation Effects on Cells- External Source- (-1987); 550400 - Genetics; 550300 - Cytology

Citation Formats

Rydberg, B. Detection of induced DNA strand breaks with improved sensitivity in human cells. United States: N. p., 1980. Web. doi:10.2307/3575208.
Rydberg, B. Detection of induced DNA strand breaks with improved sensitivity in human cells. United States. doi:10.2307/3575208.
Rydberg, B. 1980. "Detection of induced DNA strand breaks with improved sensitivity in human cells". United States. doi:10.2307/3575208.
@article{osti_5463802,
title = {Detection of induced DNA strand breaks with improved sensitivity in human cells},
author = {Rydberg, B.},
abstractNote = {When mixtures of two cell populations labeled with different radionuclides are tested with DNA unwinding technique, an accurate comparison with regard to DNA strand breaks can be made. In mixtures of irradiated and control cells, effects were detected by this technique down to a dose of 1 rad. This corresponds to 10 to 20 DNA single-strand breaks per cell, or less than one break per chromosome.},
doi = {10.2307/3575208},
journal = {Radiat. Res.; (United States)},
number = ,
volume = 81:3,
place = {United States},
year = 1980,
month = 3
}
  • Highlights: • Pre-treatment with the inhibitors increased the sensitivity of Jurkat cells to irradiation. • Combining both inhibitors together resulted in a G2 cell cycle arrest abrogation in Jurkat. • Jurkat cells pre-treated with inhibitors were positive for γH2AX foci 24 h upon irradiation. • Pre-treatment with Rad51 RI-1 had no effect on apoptosis induction in MOLT-4 cells. • When dosed together, the combination decreased MOLT-4 cell survival. - Abstract: Present-day oncology sees at least two-thirds of cancer patients receiving radiation therapy as a part of their anticancer treatment. The objectives of the current study were to investigate the effectsmore » of the small molecule inhibitors of Wee1 kinase II (681641) and Rad51 (RI-1) on cell cycle progression, DNA double-strand breaks repair and apoptosis following ionizing radiation exposure in human leukemic T-cells Jurkat and MOLT-4. Pre-treatment with the Wee1 681641 or Rad51 RI-1 inhibitor alone increased the sensitivity of Jurkat cells to irradiation, however combining both inhibitors together resulted in a further enhancement of apoptosis. Jurkat cells pre-treated with inhibitors were positive for γH2AX foci 24 h upon irradiation. MOLT-4 cells were less affected by inhibitors application prior to ionizing radiation exposure. Pre-treatment with Rad51 RI-1 had no effect on apoptosis induction; however Wee1 681641 increased ionizing radiation-induced cell death in MOLT-4 cells.« less
  • DNA strand breaks can be detected with great sensitivity by exposing crude cell lysates to alkaline solutions and monitoring the rate of strand unwinding. As little as one strand break per chromosome can be detected. Previous methods for measuring strand unwinding have required physical separation of single- from double-stranded molecules. We now describe conditions under which unwinding can be monitored directly using a fluorescent dye, thus greatly simplifying the analysis. Breaks due to irradiation of blood samples by /sup 60/Co gamma-rays at doses as low as 0.05 to 0.1 gray (5 to 10 rads) were detectable. Rapid rejoining of strandmore » breaks during in vitro incubation at 37 degrees could readily be observed following a dose of one gray. Since the procedure is very rapid and cells can be analyzed directly without the requirement for culturing or radiolabeling, the procedure could be useful in cancer chemotherapy if in vivo damage is to be monitored or for testing the in vitro sensitivity of cells to drugs.« less
  • DNA strand breaks can be detected with great sensitivity by exposing crude cell lysates to alkaline solutions and monitoring the rate of strand unwinding. As little as one strand break per chromosome can be detected. Previous methods for measuring strand unwinding have required physical separation of single- from double-stranded molecules. Researchers now describe conditions under which unwinding can be monitored directly using a fluorescent dye, thus greatly simplifying the analysis. Breaks due to irradiation of blood samples by 60Co gamma-rays at doses as low as 0.05 to 0.1 gray were detectable. Rapid rejoining of strand breaks during in vitro incubationmore » at 37 degrees could readily be observed following a dose of one gray. Since the procedure is very rapid and cells can be analyzed directly without the requirement for culturing or radiolabeling, the procedure could be useful in cancer chemotherapy if in vivo damage is to be monitored or for testing the in vitro sensitivity of cells to drugs.« less
  • DNA single-strand breaks induced by procarcinogens were detected in Chinese hamster overy (CHO) cell cocultured with adult rat hepatocytes. Freshly isolated adult rat hepatocytes were added to the CHO cell culture prelabeled with (/sup 3/H) thymidine. After allowing the hepatocytes to attach on or near the CHO cells, aflatoxin B/sub 1/ or benzo(a)pyrene was added to the culture and incubated for the desired time. DNA single-strand breaks in CHO cells were measured by the alkaline elution technique. Aflatoxin B/sub 1/ induced some DNA single-strand breaks in CHO cells cultured alone, but in coculture system with hepatocytes the number of DNAmore » single-strand breaks increased greatly. The magnitude of the increase was related to the dose and the time of exposure to aflatoxin B/sub 1/. Addition of proteinase-K to the cell lysates increased the elution of DNA compared to that of samples without proteinase-K. Benzo(a)pyrene did not induce any DNA single-strand breaks in CHO cells in the absence of liver cells, but a significant number of single-strand breaks were detected in the coculture system.« less