Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành y học dành cho các bạn tham khảo đề tài: Characterization of singlet oxygen-accumulating mutants isolated in a screen for altered oxidative stress response in Chlamydomonas reinhardtii | Fischer et al. BMC Plant Biology 2010 10 279 http 1471-2229 10 279 BMC Plant Biology RESEARCH ARTICLE Open Access Characterization of singlet oxygen-accumulating mutants isolated in a screen for altered oxidative stress response in Chlamydomonas reinhardtii Beat B Fischer1 2 Rik IL Eggen2 Krishna K Niyogi1 Abstract Background When photosynthetic organisms are exposed to harsh environmental conditions such as high light intensities or cold stress the production of reactive oxygen species like singlet oxygen is stimulated in the chloroplast. In Chlamydomonas reinhardtii singlet oxygen was shown to act as a specific signal inducing the expression of the nuclear glutathione peroxidase gene GPXH GPX5 during high light stress but little is known about the cellular mechanisms involved in this response. To investigate components affecting singlet oxygen signaling in C. reinhardtii a mutant screen was performed. Results Mutants with altered GPXH response were isolated from UV-mutagenized cells containing a GPXH-arylsulfatase reporter gene construct. Out of 5500 clones tested no mutant deficient in GPXH induction was isolated whereas several clones showed constitutive high GPXH expression under normal light conditions. Many of these GPXH overexpressor gox mutants exhibited higher resistance to oxidative stress conditions whereas others were sensitive to high light intensities. Interestingly most gox mutants produced increased singlet oxygen levels correlating with high GPXH expression. Furthermore different patterns of altered photoprotective parameters like non-photochemical quenching carotenoid contents and a-tocopherol levels were detected in the various gox mutants. Conclusions Screening for mutants with altered GPXH expression resulted in the isolation of many gox mutants with increased singlet oxygen production showing the relevance of controlling the production of this ROS in photosynthetic organisms. Phenotypic characterization of these gox .
