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Phagocytosis-induced mutagenesis in bacteria
Mutation Research
|July 1, 1983
Summary
Human immune cells called polymorphonuclear neutrophils (PMN) can revert dark bacteria to a luminescent state. This mutagenic effect involves reactive oxygen metabolites generated during phagocytosis.
Area of Science:
- Microbiology
- Immunology
- Genetics
Background:
- Luminous bacteria like Photobacterium fischeri can exist in dark, non-luminescent mutant forms.
- Human polymorphonuclear neutrophils (PMN) are key immune cells involved in phagocytosis and pathogen defense.
Purpose of the Study:
- To investigate the mutagenic potential of human PMN on dark mutants of Photobacterium fischeri.
- To elucidate the role of reactive oxygen species (ROS) in this observed mutagenic process.
Main Methods:
- Incubation of dark Photobacterium fischeri mutants with live, intact human PMN.
- Varying the phagocyte:bacterium ratio and incubation time.
- Testing the mutagenic activity of PMN supernatant.
- Assessing the effect of ROS scavengers (mannitol, benzoate, beta-carotene) and superoxide dismutase on mutagenesis.
Main Results:
- Dark mutants reverted to luminescent forms upon incubation with live PMN.
- Maximal reversion occurred within 15 minutes of phagocytosis.
- Mutagenic activity was dependent on PMN integrity and phagocyte:bacterium ratio.
- PMN supernatant retained mutagenic activity.
- ROS scavengers and superoxide dismutase inhibited the mutations.
Conclusions:
- Human PMN possess a mutagenic capacity towards dark bacterial mutants.
- Reactive oxygen metabolites generated during phagocytosis mediate this bacterial mutagenesis.
- This finding highlights a novel interaction between the innate immune system and bacterial genetics.