Related Experiment Video

Updated: Sep 25, 2026

Quantification of Plasmid-Mediated Antibiotic Resistance in an Experimental Evolution Approach
12:32

Quantification of Plasmid-Mediated Antibiotic Resistance in an Experimental Evolution Approach

Published on: December 14, 2019

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.

Journal of Radiation Research
|June 10, 2003
PubMed

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.

More Related Videos

Plasmid Stability Analysis with Open-Source Droplet Microfluidics07:43

Plasmid Stability Analysis with Open-Source Droplet Microfluidics

Published on: December 27, 2024

Daily Transfers, Archiving Populations, and Measuring Fitness in the Long-Term Evolution Experiment with Escherichia coli15:00

Daily Transfers, Archiving Populations, and Measuring Fitness in the Long-Term Evolution Experiment with Escherichia coli

Published on: August 18, 2023

Related Concept Videos

Plasmids01:28

Plasmids

Plasmids are extrachromosomal DNA molecules found in bacteria, archaea, and some eukaryotic microbes like yeast. These small, circular DNA structures typically contain fewer than 30 genes, although some may exist linearly. Plasmids vary in their number within a cell, known as copy number. Single-copy plasmids are present in one copy per cell and multi-copy plasmids are present in multiple copies, reaching over 100 copies per cell.Plasmids usually replicate independently of the chromosomal DNA...
Mutations in Microorganisms01:18

Mutations in Microorganisms

Mutations are heritable changes in an organism’s genome involving alterations in the base sequence of DNA or RNA. These changes can influence cellular processes and phenotypic traits, potentially transforming the unaltered wild type into a mutant form. Such changes, termed forward mutations, are pivotal in shaping the genetic diversity of organisms.RNA viruses exhibit the highest mutation rates due to the absence of robust proofreading mechanisms during genome replication. In contrast,...
Genomic DNA in Prokaryotes00:46

Genomic DNA in Prokaryotes

The genome of most prokaryotic organisms consists of double-stranded DNA organized into one circular chromosome in a region of cytoplasm called the nucleoid. The chromosome is tightly wound, or supercoiled, for efficient storage. Prokaryotes also contain other circular pieces of DNA called plasmids. These plasmids are smaller than the chromosome and often carry genes that confer adaptive functions, such as antibiotic resistance.
Genomic Diversity in Bacteria
Although bacterial genomes are much...
Evolution of Microbial Genome01:08

Evolution of Microbial Genome

Microbial genome evolution is a highly dynamic process shaped by continual gene gain and loss across species and strains. This genomic flexibility allows microorganisms to adapt rapidly to environmental pressures and interactions with other organisms. Central to understanding this diversity is the distinction between the core and pan genomes.The core genome comprises the genes shared by all sampled strains of a species, representing essential functions needed for fundamental cellular processes.
Evolution of New Traits in Microbes01:24

Evolution of New Traits in Microbes

Microorganisms evolve rapidly due to their large population sizes and short generation times, often exhibiting measurable changes within days under laboratory conditions. Natural selection acts on standing genetic variation, enabling the retention and amplification of beneficial traits that confer fitness advantages in changing environments.Adaptive Pigment Regulation in RhodobacterIn Rhodobacter, a genus of purple non-sulfur bacteria, light-harvesting pigments such as bacteriochlorophyll and...
Other Unique Bacteria01:18

Other Unique Bacteria

Magnetic bacteria exhibit a directed movement called magnetotaxis, driven by structures called magnetosomes. These magnetosomes consist of chains of magnetic particles made of either magnetite (Fe₃O₄) or greigite (Fe₃S₄) and are organized in a linear conformation by a protein scaffold within invaginations of the cell membrane. The bacteria align along the north–south magnetic field lines, much like a compass needle. They are typically microaerophilic or anaerobic and are commonly found near the...