Tapias Angels, Leplat Christophe, Confalonieri Fabrice
Laboratoire de Génomique des Archaea, Université Paris-Sud 11 CNRS UMR 8621, Institut de Génétique et Microbiologie, Orsay, France.
Extremophiles. 2009 Mar;13(2):333-43. doi: 10.1007/s00792-008-0221-3. Epub 2009 Jan 11.
The recently discovered hyperthermophilic and radioresistant archaeon Thermococcus gammatolerans is of great interest to compare and contrast the impact of its physiology on radioresistance and its ability to repair damaged chromosomes after exposure to gamma irradiation with radioresistant bacteria. We showed that, in contrast to other organisms, cell survival was not modified by the cellular growth phase under optimal growth conditions but nutrient-limited conditions did affect the T. gammatolerans radioresistance. We determined the first kinetics of damaged DNA recovery in an archaeon after exposure to massive doses of gamma irradiation and compared the efficiency of chromosomal DNA repair according to the cellular growth phase, nutrient availability and culture conditions. Chromosomal DNA repair kinetics showed that stationary phase cells reconstitute disrupted chromosomes more rapidly than exponential phase cells. Our data also revealed that this radioresistant archaeon was proficient to reconstitute shattered chromosomes either slowly or rapidly without any loss of viability. These results suggest that rapid DNA repair is not required for the extreme radioresistance of T. gammatolerans.
最近发现的嗜热耐辐射古菌γ-耐辐射嗜热栖热菌，对于比较和对比其生理机能对耐辐射性的影响，以及与耐辐射细菌相比，其在受到γ射线照射后修复受损染色体的能力而言，具有极大的研究价值。我们发现，与其他生物不同，在最佳生长条件下，细胞存活率并不会因细胞生长阶段而改变，但营养受限条件确实会影响γ-耐辐射嗜热栖热菌的耐辐射性。我们测定了古菌在受到大剂量γ射线照射后受损DNA恢复的首个动力学过程，并根据细胞生长阶段、营养可利用性和培养条件，比较了染色体DNA修复的效率。染色体DNA修复动力学表明，稳定期细胞比指数期细胞能更快地重建断裂的染色体。我们的数据还显示，这种耐辐射古菌能够缓慢或快速地重建破碎的染色体，且不会有任何活力损失。这些结果表明，γ-耐辐射嗜热栖热菌的极端耐辐射性并不需要快速的DNA修复。
