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Photodynamic inactivation and its repair in mycoplasmas
Abstract:
Photodynamic inactivation is the loss in viability observed when organic dye-treated cells are exposed to visible light and molecular oxygen. The photodynamic inactivation of mycoplasmas, the smallest free living cells, has been studied. Depending on the extent of inactivation in Acholeplasma laidlawii, photodynamic induced damage can be repaired if the irradiated cells are incubated in the dark in buffer. Analysis of the DNA of these cells shows that photodynamic inactivation induces single strand breaks which can be repaired during liquid holding. To examine possible damage to the cell membrane, glucose uptake was studied as a permeability measure. Neither acriflavine nor photodynamic inactivation had any measurable effect on membrane permeability.
Insights
Photodynamic inactivation damages Acholeplasma laidlawii DNA, causing single-strand breaks. This damage is repairable through dark incubation, indicating cellular repair mechanisms for photodynamic-induced lesions.
Area of Science:
- Microbiology
- Cell Biology
- Photochemistry
Background:
- Photodynamic inactivation (PDI) is a process where cells treated with photosensitizing dyes lose viability upon light exposure.
- Mycoplasmas, as the smallest self-replicating cells, are a unique model for studying cellular responses to PDI.
- Understanding PDI in mycoplasmas is crucial for antimicrobial strategies and basic cell biology research.
Purpose of the Study:
- To investigate the effects of photodynamic inactivation on the DNA and cell membrane of Acholeplasma laidlawii.
- To determine if photodynamic-induced damage in A. laidlawii is repairable.
- To assess the impact of photodynamic inactivation on mycoplasma membrane permeability.
Main Methods:
- Acholeplasma laidlawii cells were treated with organic dyes and exposed to visible light.
- DNA integrity was analyzed following photodynamic inactivation.
- Cellular repair was assessed by incubating irradiated cells in the dark.
- Glucose uptake was measured to evaluate cell membrane permeability.
Main Results:
- Photodynamic inactivation induced single-strand breaks in the DNA of Acholeplasma laidlawii.
- The DNA damage was shown to be repairable during dark incubation (liquid holding).
- Neither dye treatment nor photodynamic inactivation affected membrane permeability, as indicated by glucose uptake.
Conclusions:
- Photodynamic inactivation primarily targets DNA, causing single-strand breaks in A. laidlawii.
- A. laidlawii possesses repair mechanisms capable of restoring DNA integrity after photodynamic damage.
- The cell membrane of A. laidlawii remains functionally intact regarding permeability after photodynamic inactivation.