The effects of low dose ⁶⁰Co-gamma-radiation on radioresistance, mutagenesis, gene conversion, cell cycle and transcriptome profile in Saccharomyces cerevisiae
by Meenakshi Dwivedi, Neeta Sehgal, Madhu Bala
International Journal of Low Radiation (IJLR), Vol. 5, No. 4, 2008

Abstract: The underlying principles of low (stress)-dose Radiation-Induced Radioresistance (RIR) are inadequately understood. The present investigation focuses on understanding the genetic basis of RIR in Saccharomyces cerevisiae. In comparison with non-pre-irradiated cultures, the cultures that were pre-irradiated with a low dose of ⁶⁰Co γ-radiation showed increased survivors (32%) but decreased convertants (26%) and revertants (65%) after irradiation with a lethal dose of ⁶⁰Co γ-radiation. The radioresistance was higher if the stress dose was delivered at lower dose rate. The prolonged S-phase upregulation of genes from clusters of signal transduction, DNA damage repair, stress response, cell cycle and energy generation and down-regulation of genes from Unfolded Protein Response (UPR) pathways were observed in stress-dose irradiated cells when studied with the microarray technique. The post-irradiation variations in Heat Shock Proteins (HSPs) and the Mre11-Rad50-Xrs2 (MRX) complex were time-dependent and confirmed by real-time Quantitative-Polymerase Chain Reaction (Q-PCR) and Western blotting. This study suggests a combined role of HSPs and the MRX complex in RIR.

Online publication date: Wed, 29-Oct-2008

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