亚砷酸钠对酵母细胞抗氧化酶活性和脂质过氧化的影响

Sodium Arsenite Exposure Affects the Levels of Antioxidant Enzymes and Lipid Peroxidation in Saccharomyces cerevisiae

以模式生物酿酒酵母为材料,研究亚砷酸钠对细胞生长、抗氧化酶活性、丙二醛(MDA)含量及胞内活性氧(ROS)水平的影响。结果显示,加入亚砷酸钠(终浓度0.1~0.6 mmol·L^(-1))后,培养液在600 nm处的光密度值(OD600值)低于对照组,并呈浓度依赖性降低。经亚砷酸钠处理12 h后,酵母细胞中过氧化物酶(POD)、过氧化氢酶(CAT)、超氧化物歧化酶(SOD)和总抗氧化能力(T-AOC)活性均增高,但胞内ROS水平和MDA含量与对照组无显著差异。砷处理24 h后,POD在0.2 mmol·L^(-1)砷处理组中活性最高,而CAT、SOD和T-AOC活性呈浓度依赖性增高;胞内ROS水平和MDA含量在高浓度砷组(0.4和0.6 mmol·L^(-1))显著增高。结果表明,亚砷酸钠可抑制酵母细胞生长,改变细胞内抗氧化酶活性,较高浓度时可引起细胞氧化损伤。

Arsenic is a high toxic metalloid widely distributed in the environment. However,the underlying mechanisms of arsenic toxicity are not yet well understood. Saccharomyces cerevisiae as a model organism was selected as the materials to investigate the toxic mechanism of sodium arsenite（ As）. The results showed that cell culture density（ OD600） of yeast cells was lower in all As-treatment groups（in the concentration range of 0. 1-0. 6 mmol·L^-1）than in the control group. The values of OD600 decreased in a concentration-dependent manner. The activities of antioxidant enzymes such as superoxide dismutase（ SOD）,peroxidase（ POD）,catalase（ CAT） and total antioxidant capacity（ T-AOC） increased with increasing arsenic concentrations after yeast cells were exposed to sodium arsenite for 12 h,but no significant difference in intracellular reactive oxygen species（ ROS） level or malondialdehyde（MDA） content was found between the control and As-treatment group. After 24 h of exposure,the activities ofCAT,POD,SOD and T-AOC increased also in a concentration-dependent manner,however POD reached its peak in 0. 2 mmol·L^-1As-treatment group. And both intracellular ROS levels and MDA contents significantly increased in yeast cells after they were exposed to 0. 4 mmol·L^-1or 0. 6 mmol·L^-1sodium arsenite. These results suggested that sodium arsenite can induce cell growth inhibition,alter the activities of antioxidant defense system,and result in oxidative damage in yeast cells.