Reactive oxygen species-generated signaling
Reactive oxygen species are constantly generated during cellular metabolism and may serve as signal messenger in diverse processes ranging from subtle adjustments of activities under normal conditions to emergency signaling under extreme stress. Any imbalance in photochemistry bears a high risk for excessive reductive pressure with concomitant release of singlet oxygen, superoxide radicals and hydrogen peroxide. Such reactive oxygen species may serve as signal messenger in diverse processes ranging from subtle adjustments of activities under normal conditions to emergency signaling under stress from all cellular compartments. Reactive oxygen species have been also implicated in the specific and general signal transduction from the photosynthetic apparatus to the cytoplasm and the nucleus.