Heavy ion-induced DNA double-strand breaks in yeast.

Area of Science:

• Radiation biology
• Molecular biology
• Biophysics

Background:

• Understanding DNA damage mechanisms is crucial for radiation protection and therapy.
• Energetic heavy ions induce complex DNA damage, including double-strand breaks (DSBs).
• Saccharomyces cerevisiae is a model organism for studying DNA repair and radiation effects.

Purpose of the Study:

• To quantify the induction of DSBs in yeast by various energetic heavy ions.
• To determine the relationship between linear energy transfer (LET) and DSB induction.
• To compare DSB induction with cell inactivation to understand their correlation.

Main Methods:

• Yeast cells (Saccharomyces cerevisiae) were exposed to heavy ions, alpha particles, and X-rays.
• Pulsed-field gel electrophoresis (PFGE) was used to separate chromosomes and quantify DNA breakage.
• Fluorescence intensity analysis determined DSB cross sections and relative biological effectiveness (RBE).

Main Results:

• DSB induction increased with LET, reaching a plateau and then rising again at higher LETs.
• The relative biological effectiveness (RBE) for DNA breakage peaked around 100-200 keV/microm.
• A strong linear correlation was observed between DSB induction and cell inactivation cross sections.

Conclusions:

• Heavy ion energy deposition significantly influences DSB induction in yeast.
• DSB formation is a key factor contributing to cell inactivation by ionizing radiation.
• The findings provide insights into the biological effects of high-LET radiation.