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Effects of [3H]UdR on the cell-cycle progression of L1210 cells
Abstract:
Tritium-labelled uridine [( 3H]UdR) perturbs progression of L1210 cells through the mitotic cycle. The main effect manifests as a slowdown or arrest of a portion of cells in G2 and is already observed 2 hr after addition of 0.5-5.0 microCi/ml of [3H]UdR into cultures. At 2.5-5.0 microCi/ml of [3H]UdR a slowdown of cell progression through S is also apparent. Additionally, there is an increase in the number of cells with DNA values higher than 4C in cultures growing in the presence of [3H]UdR for 8-24 hr. A pulse of [3H]UdR of 2 hr duration labels predominantly (95%) cellular RNA. The first cell-cycle effects (G2 slowdown) are observed when the amount of the incorporated [3H]UdR is such that, on average there are fewer than thirty-six [3H] decays per cell which corresponds to approximately 12-19 rads of radiation. The S-phase slowdown is seen at a dose of incorporated [3H]UdR twice as high as that inducing G2 effects. The specific localization of [3H]UdR in nucleoli, peripheral nucleoplasm and in cytoplasm, as well as differences in the kinetics of the incorporation in relation to phases of the cell cycle are discussed in the light of the differences between the effects of [3H]UdR and [3H]thymidine. Mathematical modelling of the cell-cycle effects of [3H]UdR is provided.
Insights
Tritium-labelled uridine ([3H]UdR) disrupts cell division, causing G2 phase slowdown and S phase delays in L1210 cells. These effects occur at low radiation doses, impacting cell cycle progression.
Area of Science:
- Cell Biology
- Molecular Biology
- Radiochemistry
Background:
- Tritium-labelled uridine ([3H]UdR) is used to study RNA synthesis and cell cycle dynamics.
- Understanding the impact of radiolabeling on cell progression is crucial for interpreting experimental results.
Purpose of the Study:
- To investigate the effects of [3H]UdR on the mitotic cell cycle progression of L1210 cells.
- To determine the radiation dose and incorporation levels associated with observed cell cycle perturbations.
Main Methods:
- Exposure of L1210 cell cultures to varying concentrations of [3H]UdR.
- Analysis of cell cycle distribution using DNA content measurements.
- Quantification of incorporated [3H]UdR and estimation of radiation dose per cell.
Main Results:
- [3H]UdR addition caused a G2 phase slowdown/arrest within 2 hours, observable at 0.5-5.0 microCi/ml.
- S phase progression was also slowed at higher [3H]UdR concentrations (2.5-5.0 microCi/ml).
- Increased cells with DNA >4C were noted after 8-24 hours of exposure, indicating potential polyploidy or endoreduplication.
Conclusions:
- [3H]UdR significantly perturbs cell cycle progression, primarily affecting G2 and S phases.
- Observed cell cycle effects are linked to low radiation doses from [3H]UdR decay.
- The localization and incorporation kinetics of [3H]UdR contribute to its distinct effects compared to [3H]thymidine.