Related Experiment Videos
Early postirradiation chromatin degradation in thymocytes
V A Soldatenkov1, M F Denisenko, N N Khodarev
1Institute of Biophysics, U.S.S.R. Department of Health, Moscow.
International Journal of Radiation Biology
|June 1, 1989
Summary
Irradiation causes DNA fragmentation in thymocytes, an early event in programmed cell death. This process requires protein synthesis and results in specific DNA fragment sizes.
Area of Science:
- Molecular Biology
- Cell Biology
- Radiation Biology
Background:
- Programmed cell death, or apoptosis, is a crucial biological process.
- Irradiation is known to induce cell death in various cell types.
Purpose of the Study:
- To investigate the kinetics and mechanisms of DNA fragmentation in thymocytes following in vivo irradiation.
- To determine if DNA fragmentation is an early event in irradiation-induced thymocyte apoptosis and if it requires protein synthesis.
Main Methods:
- In vivo irradiation of mice.
- Analysis of DNA size distribution in thymocytes over time.
- Isolation of nuclear extracts and assessment of nuclease activity.
- Effect of cycloheximide on nuclease activity.
Main Results:
- Average DNA size in thymocytes decreased rapidly after irradiation, reaching a plateau by 45 minutes.
- Accumulation of 1.0-1.5 kb DNA fragments was observed, indicating non-random DNA cleavage.
- Double-strand breaks were clustered, producing fragments consistent with 1-5 nucleosome sizes.
- Cycloheximide partially inhibited nuclease activity in irradiated thymocyte extracts.
Conclusions:
- DNA fragmentation is an early event in irradiation-induced programmed thymocyte death.
- The process requires de novo protein synthesis.
- DNA fragmentation precedes the release of polydeoxyribonucleotides.