Abstract:

To explore the impact of inorganic arsenic stress on physiology of Sargassum horneri, the 8 physiological indexes about oxidative damage, antioxidant enzymes and antioxidant were detected while the germlings of S. horneri were shortly treated with different concentrations (0, 50, 100, 150, 200 mmol∙L^-1) of As³⁺ and As⁵⁺, respectively. The results showed that rate of oxygen free radical (OFR) production and content of malondialdehyde (MDA) in S. horneri seedlings increased significantly with increasing concentration of As³⁺ or As⁵⁺, and the damage rate of cellular was also elevated simultaneously. The medium effect concentrations (EC₅₀) of As³⁺ and As⁵⁺ to S. horneri were 50.1 and 116.3 mmol∙L^-1, respectively. Activities of superoxide dismutase (SOD) and peroxidase (POD) showed an upward trend in general, while catalase (CAT) varied insignificantly. The content of glutathione (GSH) increased first and then decreased with increase of As³⁺ concentration, whereas it showed an overall upward trend with increase of As⁵⁺ concentration. The content of non-protein thiol compound (NPT) tended to ascend first, then reduce with increasing As³⁺ or As⁵⁺ concentration. The principal component analysis of the S. horneri antioxidant system showed that the 50 mmol∙L^-1 (As³⁺) and 100 mmol∙L^-1 (As⁵⁺) treatments had higher comprehensive score of antioxidant system rather than others. As the concentration of As³⁺ and As⁵⁺ increased, the contribution of antioxidants (GSH, NPT) to the S. horneri antioxidant system weakened, while the contribution of antioxidase (SOD, POD) to the antioxidant system increased relatively.

Key words: valence state, antioxidase, antioxidant, principal component analysis, medium effect concentration

摘要：

为探讨无机砷胁迫对铜藻（Sargassum horneri）的生理影响,对铜藻幼苗在不同浓度（0、50、100、150、200 mmol∙L^-1）的As³⁺、As⁵⁺短期胁迫条件下其氧化损伤、抗氧化酶、抗氧化物等8项生理指标进行了测定。结果显示,随着As³⁺、As⁵⁺浓度的增加,铜藻体内的氧自由基（Oxygen free radical,OFR）产生速率、丙二醛（Malondialdehyde,MDA）含量明显升高,铜藻细胞损伤率也同时上升。As³⁺、As⁵⁺对铜藻的半效应浓度（Median effect concentration,EC₅₀）分别为50.1、116.3 mmol∙L^-1。随As处理浓度升高,藻体超氧化物歧化酶（Superoxide dismutase,SOD）和过氧化物酶（Peroxidase,POD）活性呈上升趋势,而过氧化氢酶（Catalase,CAT）活性则无明显变化。谷胱甘肽（Glutathione,GSH）含量随As³⁺浓度的增加呈先升后降,而随As⁵⁺浓度的增加总体呈上升趋势。非蛋白巯基化合物（Non-protein thiol,NPT）含量随As³⁺、As⁵⁺浓度的升高而先升后降。对铜藻抗氧化系统主成分分析表明,As³⁺ 50mmol∙L^-1及As⁵⁺ 100mmol∙L^-1实验组的铜藻抗氧化综合得分较高;随着As³⁺、As⁵+浓度的升高,抗氧化物（GSH、NPT）对铜藻抗氧化系统的贡献减弱,而抗氧化酶（SOD、POD）对铜藻抗氧化系统的贡献相对增强。

关键词: 价态, 抗氧化酶, 抗氧化物, 主成分分析, 半效应浓度