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Transfection with heteroduplex SPP1 DNA: a pyrimidine dimer induced influence on the conversion pattern
Molecular & General Genetics : MGG
|August 5, 1975
Summary
Pyrimidine dimers in SPP1 DNA heteroduplexes affect Bacillus subtilis transfection outcomes. Excision repair of these dimers influences the ratio of wild type to mutant progeny, suggesting dimer-induced co-excision.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Bacterial transformation involves DNA uptake and recombination.
- DNA damage, such as pyrimidine dimers, can impact genetic processes.
- Excision repair mechanisms are crucial for maintaining genome integrity.
Purpose of the Study:
- To investigate the role of pyrimidine dimer excision repair in Bacillus subtilis transfection.
- To determine how UV-induced DNA damage influences the genotype ratio of progeny in SPP1 heteroduplex transfections.
- To elucidate the mechanism behind observed changes in DNA conversion patterns.
Main Methods:
- Transfection of Bacillus subtilis competent cells with SPP1 heteroduplices containing pyrimidine dimers.
- Utilizing host cells with different excision repair capabilities (her+ and her-).
- Irradiating specific strands of heteroduplices to introduce pyrimidine dimers.
Main Results:
- Excision repair of pyrimidine dimers significantly influences the wild type to mutant progeny ratio.
- Increased UV dose to one strand elevates the percentage of infective centers with the unirradiated strand genotype.
- Comparison between her+ and her- hosts ruled out asymmetric replication as the cause of conversion pattern changes.
- Data support a model of dimer-induced co-excision of mismatched regions.
Conclusions:
- Pyrimidine dimer excision repair is a key factor modulating genetic outcomes during transfection.
- The observed changes in progeny genotype ratios are likely due to dimer-induced co-excision.
- The study excludes the excision of wild-type loops during uptake as a contributing factor.