Pagliano Cristina, Raviolo Marco, Dalla Vecchia Francesca, Gabbrielli Roberto, Gonnelli Cristina, Rascio Nicoletta, Barbato Roberto, La Rocca Nicoletta
Dipartimento di Scienze dell Ambiente e della Vita, Università del Piemonte Orientale Amedeo Avogadro,Via Bellini 25G, I-15100 Alessandria, Italy.
J Photochem Photobiol B. 2006 Jul 3;84(1):70-8. doi: 10.1016/j.jphotobiol.2006.01.012. Epub 2006 Mar 15.
The effects of cadmium (from 7.5 to 75 microM) on chloroplasts of rice were studied at the structural and biochemical level. Loss of pigments, reduction of thylakoids and decrease in oxygen evolution and Fv/Fm ratio occur in leaves following cadmium treatment. However, the amount of photosystem II reaction center proteins and that of its light harvesting complex is not affected, indicating that cadmium does not adversely influence the structural organization of this photosystem. In thylakoids isolated from cadmium-treated plants a loss in the capability to reduce 2,6-dichlorophenolindophenol is observed, which is partially restored if diphenylcarbazide is used as an electron donor, indicating that cadmium affects water splitting activity. In thylakoids isolated from control plants and treated with cadmium, diphenylcarbazide preserves most of the photosystem II activity lost after incubation with cadmium; most of the S(2) multiline electron paramagnetic resonance signal from the manganese cluster is lost, whereas the TyrD(+) and other signals are retained. Light-induced photosystem II damage, in vitro, is promoted by Cd-treatment as deduced from the mobility shift of the D1 protein observed by immunoblot.
研究了镉（浓度为7.5至75微摩尔）对水稻叶绿体在结构和生化水平上的影响。镉处理后，叶片出现色素损失、类囊体减少、氧气释放量降低以及Fv/Fm比值下降。然而，光系统II反应中心蛋白及其捕光复合体的含量不受影响，这表明镉不会对该光系统的结构组织产生不利影响。在从镉处理的植物中分离出的类囊体中，观察到还原2,6 - 二氯酚靛酚的能力丧失，如果使用二苯卡巴肼作为电子供体，这种能力会部分恢复，这表明镉会影响水的光解活性。在从对照植物中分离并经镉处理的类囊体中，二苯卡巴肼能保留与镉孵育后丧失的大部分光系统II活性；锰簇的大部分S(2)多线电子顺磁共振信号丧失，而TyrD(+)和其他信号则保留。从免疫印迹观察到的D1蛋白迁移率变化推断，体外光诱导的光系统II损伤在镉处理时会加剧。
