Cheng Jinfeng, Qiu Hongchen, Chang Zhaoyang, Jiang Zaimin, Yin Wenke
The College of Life Sciences, Northwest A&F University, Yangling, 712100 Shaanxi China.
College of Mechanical and Electronic Engineering, Northwest A&F University, Yangling, 712100 Shaanxi China.
Springerplus. 2016 Aug 8;5(1):1290. doi: 10.1186/s40064-016-2963-1. eCollection 2016.
The objective of the present work was to evaluate the effect of exogenously applied cadmium on the physiological response of green algae Chlorella vulgaris. The study investigated the long-term effect (18 days) of cadmium on the levels of algae biomass, assimilation pigment composition, soluble protein, oxidative status (production of hydrogen peroxide and superoxide anion), antioxidant enzymes (such as superoxide dismutase, peroxidase, catalase and glutathione reductase enzyme) in C. vulgaris. The results showed that growth, the amount of chlorophyll a (Chl a), chlorophyll b (Chl b) and carotenoids gradually decreased with increasing cadmium over 18 days exposure. Cadmium at concentration of 7 mg L(-1) inhibited algal growth expressed as the number of cells. Our research found that C. vulgaris has a high tolerance to cadmium. Contents of chlorophylls (Chl a and Chl b) and carotenoids (Car) of C. vulgaris was significantly decline with rising concentration of cadmium (p < 0.05). The decrease of 54.04 and 93.37 % in Chl a, 60.65 and 74.32 % in Chl b, 50.00 and 71.88 % in total carotenoids was noticed following the treatment with 3 and 7 mg L(-1) cadmium doses compared with control treatment, respectively. Cadmium treatments caused a significant change in the physiological competence (calculated as chlorophyll a/b) which increased with increasing Cd(II) doses up to 1 mg L(-1) but decreased at 3 mg L(-1). While accumulation of soluble protein was enhanced by presence of cadmium, the treatment with cadmium at 3 and 7 mg L(-1) increased the concentration of soluble proteins by 88, 95.8 % in C. vulgaris, respectively. Moreover, low doses of cadmium stimulated enzymatic (superoxide dismutase, catalase and glutathione reductase) in C. vulgaris, The content of peroxidase increased with the increasing cadmium concentration, and had slightly decreased at the concentration of 7 mg L(-1), but was still higher than control group, which showed that cadmium stress at high concentration mainly peroxidase works in C. vulgaris. And therefore, suppressed reactive oxygen species (hydrogen peroxide and superoxide) accumulated. The present study also showed that cadmium increased oxidative stress and induced antioxidant defense systems against reactive oxygen species. The observation in here analyzed C. vulgaris after exposure to cadmium indicate that hydrogen peroxide, superoxide and peroxidase in the alga with exposure to Cd(II) seemed to be parameters as biomarkers for metal-induced oxidative stress.
本研究的目的是评估外源施加镉对绿藻普通小球藻生理反应的影响。该研究调查了镉对普通小球藻生物量水平、同化色素组成、可溶性蛋白、氧化状态（过氧化氢和超氧阴离子的产生）、抗氧化酶（如超氧化物歧化酶、过氧化物酶、过氧化氢酶和谷胱甘肽还原酶）的长期影响（18天）。结果表明，在18天的暴露过程中，随着镉含量的增加，普通小球藻的生长、叶绿素a（Chl a）、叶绿素b（Chl b）和类胡萝卜素的含量逐渐降低。浓度为7 mg L⁻¹的镉抑制了以细胞数量表示的藻类生长。我们的研究发现普通小球藻对镉具有较高的耐受性。普通小球藻的叶绿素（Chl a和Chl b）和类胡萝卜素（Car）含量随着镉浓度的升高而显著下降（p < 0.05）。与对照处理相比，用3和7 mg L⁻¹镉剂量处理后，Chl a分别下降了54.04%和93.37%，Chl b分别下降了60.65%和74.32%，总类胡萝卜素分别下降了50.00%和71.88%。镉处理导致生理能力（以叶绿素a/b计算）发生显著变化，在镉（II）剂量增加至1 mg L⁻¹时升高，但在3 mg L⁻¹时下降。虽然镉的存在增强了可溶性蛋白的积累，但在普通小球藻中，3和7 mg L⁻¹的镉处理分别使可溶性蛋白浓度增加了88%、95.8%。此外，低剂量的镉刺激了普通小球藻中的酶活性（超氧化物歧化酶、过氧化氢酶和谷胱甘肽还原酶），过氧化物酶的含量随着镉浓度的增加而增加，在7 mg L⁻¹浓度时略有下降，但仍高于对照组，这表明高浓度的镉胁迫主要是过氧化物酶在普通小球藻中起作用。因此，抑制了活性氧（过氧化氢和超氧阴离子）的积累。本研究还表明，镉增加了氧化应激并诱导了针对活性氧的抗氧化防御系统。此处对暴露于镉后的普通小球藻的观察表明，表示金属诱导的氧化应激的生物标志物的参数似乎是藻类中过氧化氢、超氧阴离子和过氧化物酶。
