Singlet oxygen (¹O₂) is an important damaging agent, which is produced during illumination by the interaction of the triplet excited state pigment molecules with molecular oxygen. In cells of photosynthetic organisms ¹O₂ is formed primarily in chlorophyll containing complexes, and damages pigments, lipids, proteins and other cellular constituents in their environment. A useful approach to study the physiological role of ¹O₂ is the utilization of external photosensitizers. In the present study, we employed a multiwell plate-based screening method in combination with chlorophyll fluorescence imaging to characterize the effect of externally produced ¹O₂ on the photosynthetic activity of isolated thylakoid membranes and intact Chlorella sorokiniana cells. The results show that the external ¹O₂ produced by the photosensitization reactions of Rose Bengal damages Photosystem II both in isolated thylakoid membranes and in intact cells in a concentration dependent manner indicating that ¹O₂ plays a significant role in photodamage of Photosystem II.

单线态氧（¹ O ₂）是一种重要的破坏剂，它是在光照过程中由三线态激发态色素分子与分子氧相互作用产生的。在光合生物的细胞中，¹ O ₂主要在含有叶绿素的复合物中形成，并破坏其环境中的色素、脂质、蛋白质和其他细胞成分。^研究1 O ₂生理作用的一个有用方法是使用外部光敏剂。在本研究中，我们采用基于多孔板的筛选方法结合叶绿素荧光成像来表征外部产生的¹ O₂关于分离的类囊体膜和完整的Chlorella sorokiniana细胞的光合活性。结果表明，玫瑰红光敏反应产生的外部¹ O ₂对离体类囊体膜和完整细胞中的光系统II均具有浓度依赖性，表明¹ O ₂在光系统II的光损伤中起重要作用。