[A model for indication of DNA functional and structural changes at low-dose radiation]

Area of Science:

• Molecular Biology
• Radiation Biology
• Genetics

Background:

• Gamma irradiation can induce structural and functional DNA damage.
• Assessing DNA damage requires reliable experimental models.
• Plasmid-based assays are valuable tools for studying DNA integrity.

Purpose of the Study:

• To develop and validate an "in vivo-in vitro" model for detecting DNA damage caused by gamma irradiation.
• To quantify the effects of low-dose gamma irradiation on plasmid DNA structure and function.
• To assess the impact of radiation-induced DNA damage on gene expression and bacterial transformation.

Main Methods:

• Utilized an "in vivo-in vitro" system employing gamma-irradiated pTTQ 19 plasmid (containing ampicillin resistance and lacZ alpha genes) as a DNA donor.
• Transformed E. coli GM 109 bacterial strain with the irradiated plasmid.
• Analyzed structural plasmid DNA damage using agarose gel electrophoresis.
• Assessed functional DNA damage by measuring ampicillin resistance transfer and beta-galactosidase activity in transformed E. coli.

Main Results:

• Structural DNA damage was observed in the irradiated plasmid.
• Functional damage manifested as a dose-dependent decrease in beta-galactosidase activity.
• The number of ampicillin-resistant E. coli transformants decreased with increasing radiation dose (24.5% at 0.05 Gy, 30.9% at 0.19 Gy, 40.2% at 0.25 Gy).

Conclusions:

• The developed "in vivo-in vitro" model effectively identifies both structural and functional DNA damages induced by gamma irradiation.
• Low-dose gamma irradiation significantly impairs plasmid DNA function, affecting gene expression and transformation efficiency.
• This model provides a sensitive method for evaluating the genotoxic effects of ionizing radiation.