Gomes-Junior Rui A, Gratão Priscila L, Gaziola Salete A, Mazzafera Paulo, Lea Peter J, Azevedo Ricardo A
Centro de Estudos Superiores de Balsas, Universidade Estadual do Maranhão, 65800-000, Balsas, MA, Brazil.
Departamento de Genética, Escola Superior de Agricultura Luiz de Queiroz, Universidade de São Paulo, 13418-900 Piracicaba, SP, Brazil.
Funct Plant Biol. 2007 Jun;34(5):449-456. doi: 10.1071/FP07010.
Selenium (Se) is an essential element for humans and animals that is required for key antioxidant reactions, but can be toxic at high concentrations. We have investigated the effect of Se in the form of selenite on coffee cell suspension cultures over a 12-day period. The antioxidant defence systems were induced in coffee cells grown in the presence of 0.05 and 0.5 mm sodium selenite (NaSeO). Lipid peroxidation and alterations in antioxidant enzymes were the main responses observed, including a severe reduction in ascorbate peroxidase activity, even at 0.05 mm sodium selenite. Ten superoxide dismutase (SOD) isoenzymes were detected and the two major Mn-SOD isoenzymes (bands V and VI) responded more to 0.05 mm selenite. SOD band V exhibited a general decrease in activity after 12 h of treatment with 0.05 mm selenite, whereas band VI exhibited the opposite behavior and increased in activity. An extra isoenzyme of glutathione reductase (GR) was induced in the presence of selenite, which confirmed our previous results obtained with Cd and Ni indicating that this GR isoenzyme may have the potential to be a marker for oxidative stress in coffee.
硒（Se）是人和动物必需的元素，参与关键的抗氧化反应，但高浓度时具有毒性。我们研究了亚硒酸盐形式的硒在12天内对咖啡细胞悬浮培养物的影响。在含有0.05和0.5 mM亚硒酸钠（NaSeO）的条件下生长的咖啡细胞中，抗氧化防御系统被诱导。观察到的主要反应包括脂质过氧化和抗氧化酶的变化，即使在0.05 mM亚硒酸钠存在下，抗坏血酸过氧化物酶活性也会严重降低。检测到十种超氧化物歧化酶（SOD）同工酶，两种主要的锰超氧化物歧化酶同工酶（条带V和VI）对0.05 mM亚硒酸盐的反应更强。用0.05 mM亚硒酸盐处理12小时后，SOD条带V的活性普遍下降，而条带VI表现出相反的行为，活性增加。在亚硒酸盐存在下诱导产生了一种额外的谷胱甘肽还原酶（GR）同工酶，这证实了我们之前用镉和镍获得的结果，表明这种GR同工酶可能有潜力成为咖啡氧化应激的标志物。
