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Mutation frequency of plasmid DNA and Escherichia coli following long-term space flight on Mir
Akihisa Takahashi1, Ken Ohnishi, Akitoshi Yokota
1Department of Biology, Nara Medical University, 840 Shijo-cho, Kashihara, Nara, 634-8521, Japan.
Abstract:
To elucidate the biological influence of space radiation, we studied the effects of long-term space flight on mutation of the bacterial ribosomal protein L gene (rpsL). We prepared dried samples of plasmid DNA and repair-deficient and wild type cells of Escherichia (E.) coli. After a 40-day space flight on board the Russian space station Mir, the mutation frequencies of the rpsL gene were estimated by transformation of E. coli and by assessment of conversion of rpsL wild type phenotype (SmS) to its mutant phenotype (SmR). The experimental findings indicate that mutation frequencies of space samples were not significantly different from those of ground control samples in plasmid DNA and both E. coli strains. It may suggest that space radiation did not influence mutation frequency.
Insights
Long-term space flight did not significantly alter mutation frequencies in bacterial ribosomal protein L gene (rpsL) samples. This suggests space radiation may not impact bacterial gene mutation rates.
Area of Science:
- Astrobiology
- Molecular Biology
- Radiation Biology
Background:
- Understanding the biological effects of space radiation is crucial for astronaut safety and the search for extraterrestrial life.
- The ribosomal protein L gene (rpsL) is a sensitive marker for bacterial mutations.
Purpose of the Study:
- To investigate the impact of long-term space flight on the mutation frequency of the bacterial rpsL gene.
- To assess whether space radiation influences mutation rates in plasmid DNA and Escherichia coli (E. coli) cells.
Main Methods:
- Dried plasmid DNA and two strains of E. coli (repair-deficient and wild type) were exposed to space radiation during a 40-day space flight on the Russian space station Mir.
- Mutation frequencies were determined by E. coli transformation and by assessing the conversion of the rpsL wild type phenotype (SmS) to its mutant phenotype (SmR).
Main Results:
- No significant differences in rpsL gene mutation frequencies were observed between space-flown samples and ground control samples.
- This held true for both plasmid DNA and the E. coli strains used in the experiment.
Conclusions:
- The study suggests that space radiation, under the conditions tested, did not significantly influence the mutation frequency of the bacterial rpsL gene.
- Further research may be needed to explore potential subtle effects or different biological systems.