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Spontaneously occurring bacterial transformations in mice
Abstract:
In 1963, it was reported that deoxyribonucleic acid (DNA)-mediated transformations could take place spontaneously between genetically distinguishable pneumococci growing in a living host, the mouse. It was found in the present study that such transformations could be increased in frequency if infected animals were treated with a drug which kills only one of the two infecting strains. The frequency of in vivo transformations was also increased if the infection was prolonged. Interspecific transformation between pneumococci and streptococci without the addition of purified DNA was demonstrated both in vitro and in vivo. These results make it seem more likely that DNA-mediated transformations occur in nature.
Insights
Bacterial transformation frequency, a process involving deoxyribonucleic acid (DNA), increased in mice when one bacterial strain was eliminated or infections were prolonged. This suggests natural DNA-mediated transformations occur in vivo.
Area of Science:
- Microbiology
- Genetics
- Molecular Biology
Background:
- Deoxyribonucleic acid (DNA)-mediated transformation in pneumococci was first reported in 1963.
- Spontaneous transformation occurs between genetically distinct pneumococci within a host.
- The natural occurrence and frequency-modulating factors of in vivo transformation require further investigation.
Purpose of the Study:
- To investigate factors influencing the frequency of in vivo DNA-mediated transformations.
- To explore interspecific transformations between different bacterial species.
- To assess the likelihood of natural DNA-mediated transformations.
Main Methods:
- Infection of mice with two genetically distinguishable pneumococcal strains.
- Treatment of infected animals with a selective drug targeting one strain.
- Prolonging the duration of infection.
- In vitro and in vivo co-cultivation of pneumococci and streptococci without purified DNA.
Main Results:
- Selective drug treatment significantly increased the frequency of in vivo transformations.
- Prolonged infection duration also led to a higher frequency of in vivo transformations.
- Interspecific transformation between pneumococci and streptococci was observed without added DNA.
Conclusions:
- Factors such as selective pressure and infection duration can enhance in vivo bacterial transformation.
- Bacterial transformation can occur between different species, even without purified DNA.
- The findings support the hypothesis that DNA-mediated transformations are a natural biological phenomenon.