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Alkylating agent (MNU)-induced mutation in space environment
T Ohnishi1, A Takahashi, K Ohnishi
1Department of Biology, Nara Medical University, Kashihara, Japan. tohnishi@naramed-u.ac.jp
Advances in Space Research : the Official Journal of the Committee on Space Research (COSPAR)
|January 22, 2002
Summary
Microgravity had no significant effect on DNA replication or mutation frequency when using DNA damaged by N-methyl-N-nitroso urea (MNU). This suggests spaceflight conditions do not alter DNA repair during replication.
Area of Science:
- Space Biology
- Molecular Biology
- Genetics
Background:
- Conflicting data exists regarding microgravity's impact on radiation-induced biological responses in space.
- Understanding DNA replication fidelity under microgravity is crucial for astronaut health and long-duration space missions.
Purpose of the Study:
- To investigate the effect of microgravity on DNA replication and mutation frequency using a DNA template damaged by an alkylating agent.
- To determine if microgravity influences the rate of incorrect base incorporation during DNA synthesis.
Main Methods:
- An in vitro enzymatic DNA synthesis system was employed using Taq polymerase and polymerase III.
- DNA templates damaged by N-methyl-N-nitroso urea (MNU) were replicated during a US space shuttle mission (Discovery, STS-91).
- DNA replication and mutation frequencies were quantified post-flight.
Main Results:
- Microgravity exposure showed negligible effects on both DNA replication rates and mutation frequencies.
- The frequency of mutations induced by the alkylating agent remained largely unchanged in microgravity compared to ground controls.
Conclusions:
- Microgravity does not appear to significantly affect DNA replication fidelity or the mutation frequency induced by chemical mutagens.
- The findings suggest that microgravity may not impact the substrate incorporation stage of induced DNA damage repair.