硒对镉胁迫下酿酒酵母抗氧化活性的影响

利用酿酒酵母（Saccharomyces cerevisiae）作为模式生物，主要通过测定硒对镉胁迫下酿酒酵母细胞内活性氧（reactive oxygen species，ROS）和丙二醛（malondialdehyde，MDA）含量，及重要抗氧化酶包括超氧化物歧化酶（superoxide dismutase，SOD）、过氧化氢酶（catalase，CAT）、谷胱甘肽过氧化物酶（glutathione peroxidase，GSH-Px）和过氧化物酶（peroxidase，POD）抗氧化活性的变化，研究硒对镉胁迫下酿酒酵母的抗氧化活性的影响。结果表明：镉处理能极显著提高酿酒酵母细胞内ROS和MDA含量（P＜0.01），进而对酿酒酵母细胞产生氧化胁迫，在培养体系内加入一定量的外源硒可极显著（P＜0.01）增加酿酒酵母细胞内抗氧化酶SOD、POD、CAT和GSH-Px活性，提高抗氧化物谷胱甘肽含量，加强酿酒酵母细胞对ROS和MDA的清除能力，这些结果表明外源硒的添加在酿酒酵母体内亦可对镉的影响产生拮抗作用，且与在动植物体内表现出一致的趋势，后续可以利用酿酒酵母作为模式生物进一步研究硒对镉毒性拮抗作用的一些机制。

Effects of Selenium on Antioxidant Activity of Saccharomyces cerevisiae under Cadmium Stress

The aim of this paper was to examine the effects of selenium on the antioxidant activity of Saccharomyces cerevisiae under cadmium stress. The levels of reactive oxygen species (ROS) and malondialdehyde (MDA), and the activities of important antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and peroxidase (POD) in S. cerevisiae cells were determined. The results obtained showed that cadmium treatment could significantly increase the contents of ROS and MDA in S. cerevisiae (P < 0.01), consequently generating oxidative stress. When a certain amount of exogenous selenium was added to the culture system, the activities of SOD, POD, CAT and GSH-Px were significantly increased (P < 0.01). The content of antioxidant GSH was also increased, enhancing the ability to scavenge ROS and MDA. These results indicated that the addition of exogenous selenium could also antagonize cadmium effects in S. cerevisiae, and this effect was also observed in plants and animals. S. cerevisiae could be used as a model organism for further study to investigate the mechanisms of selenium antagonism towards cadmium toxicity.