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Degradation of DNA by nucleases in intestinal tract of rats
Abstract:
Strains of Escherichia coli K12 have been constructed as safer hosts for use in recombinant DNA research, These strains are unable to survive passage through the intestinal tracts of rats because of a constellation of mutations conferring bile sensitivity and requirements for diaminopimelic acid and thymine. Since death caused by diaminopimelic acid deprivation could release recombinant DNA before DNA is degraded because of thymine starvation, it is important to determine the "survival potential" of the released DNA's. Bacterial and plasmid DNA's extracted from bacterial cells are rapidly degraded when added to low dilutions of rat intestinal contents. This observation, coupled with the stringent requirements necessary for in vitro transformation or transfection, make in vivo transmission of naked recombinant DNA in the rat intestinal tract highly improbable.
Insights
Safer Escherichia coli K12 strains are engineered for recombinant DNA research. These strains exhibit low survival in rat intestines, making in vivo transmission of recombinant DNA highly unlikely due to rapid DNA degradation.
Area of Science:
- Microbiology
- Molecular Biology
- Genetic Engineering
Background:
- Escherichia coli K12 strains are widely used in recombinant DNA research.
- Development of safer strains is crucial for mitigating risks associated with genetic engineering.
Purpose of the Study:
- To assess the survival potential of engineered Escherichia coli K12 strains in a mammalian intestinal environment.
- To evaluate the probability of in vivo transmission of recombinant DNA within the rat intestinal tract.
Main Methods:
- Construction of Escherichia coli K12 strains with mutations conferring bile sensitivity and auxotrophy for diaminopimelic acid and thymine.
- Assessment of bacterial survival and DNA degradation rates in rat intestinal contents.
- Evaluation of in vitro transformation and transfection efficiencies.
Main Results:
- Engineered E. coli K12 strains demonstrated inability to survive passage through rat intestinal tracts.
- Bacterial and plasmid DNA were rapidly degraded in low dilutions of rat intestinal contents.
- Stringent requirements for in vitro DNA transformation/transfection were observed.
Conclusions:
- In vivo transmission of naked recombinant DNA in the rat intestinal tract is highly improbable.
- Engineered E. coli K12 strains offer a significant safety enhancement for recombinant DNA research.