The effects of hypoosmotic shock on state transition in darkness in Dunaliella salina were studied. When the concentration of NaCl in culture medium was dropped from 1.5 to 0.5 mol/L abruptly, the photosynthetic rate ...The effects of hypoosmotic shock on state transition in darkness in Dunaliella salina were studied. When the concentration of NaCl in culture medium was dropped from 1.5 to 0.5 mol/L abruptly, the photosynthetic rate of D. salina declined, but the respiratory rate and in- tracellular ATP content increased in the dark. The FPSⅡ/FPSⅠ ratio at 77 K of D. salina cells exposed to hypoosmotic shock was higher than that of control cells, indicating that more excitation energy was distributed to PSⅡ in stressed D. salina cells upon illumination. A decrease in LHCⅡ pho- sphorylation level was also observed when D. salina was exposed to hypoosmotic shock. Thus a stateⅠtransition of photosynthetic apparatus occurs when D. salina suffers hypoosmotic shock in darkness, which is supposed to be related to an enhancement of respiration and an increase in ATP content in stressed D. salina cells.展开更多
IN the course of plant life, many physiological and biochemical processes are controlled by extracellular signals (light, temperature, gravity, water, hormone, etc. ). How the cells perceive these environmental signal...IN the course of plant life, many physiological and biochemical processes are controlled by extracellular signals (light, temperature, gravity, water, hormone, etc. ). How the cells perceive these environmental signals, transduce them inwards and lead to alterations of intracellular physiology has become a focus in life science these years. Research in this field was started earher and further developed in animal cells. When specific receptors on the external surfaceof ammal cells perceive an extracellular signal, specific phospholipase C (PLC) isozymes are activated, signaled by the cleavage of inositol phospholipids to release second messengers, i.e.展开更多
文摘The effects of hypoosmotic shock on state transition in darkness in Dunaliella salina were studied. When the concentration of NaCl in culture medium was dropped from 1.5 to 0.5 mol/L abruptly, the photosynthetic rate of D. salina declined, but the respiratory rate and in- tracellular ATP content increased in the dark. The FPSⅡ/FPSⅠ ratio at 77 K of D. salina cells exposed to hypoosmotic shock was higher than that of control cells, indicating that more excitation energy was distributed to PSⅡ in stressed D. salina cells upon illumination. A decrease in LHCⅡ pho- sphorylation level was also observed when D. salina was exposed to hypoosmotic shock. Thus a stateⅠtransition of photosynthetic apparatus occurs when D. salina suffers hypoosmotic shock in darkness, which is supposed to be related to an enhancement of respiration and an increase in ATP content in stressed D. salina cells.
文摘IN the course of plant life, many physiological and biochemical processes are controlled by extracellular signals (light, temperature, gravity, water, hormone, etc. ). How the cells perceive these environmental signals, transduce them inwards and lead to alterations of intracellular physiology has become a focus in life science these years. Research in this field was started earher and further developed in animal cells. When specific receptors on the external surfaceof ammal cells perceive an extracellular signal, specific phospholipase C (PLC) isozymes are activated, signaled by the cleavage of inositol phospholipids to release second messengers, i.e.
