五价砷胁迫处理对普通小球藻的急性毒性效应

为探究重金属砷在水域生态系统中的毒性作用及机制,以典型浮游植物指示种普通小球藻(Chlorella vulgaris)为试验对象,通过设置不同浓度As⁵⁺(0、0.1、0.5、1、1.5和2 mg/L)研究其对普通小球藻的藻密度、叶绿素a含量、细胞膜通透性、蛋白(TP)含量、活性氧自由基(ROS)含量、丙二醛(MDA)含量、总抗氧化能力(T-AOC)、总超氧化歧化酶(T-SOD)活性、三磷酸腺苷酶(ATP)活性和超微结构的影响。研究结果表明,在96h胁迫内,各浓度As⁵⁺处理组对普通小球藻的生长均有抑制作用,其中2 mg/L处理组抑制率最高,为52.9%,96h-IC50为1.94 mg/L。各处理组对藻细胞Chl.a含量也均有抑制作用,其中2 mg/L处理组最低,仅为对照组的31.4%。As⁵⁺浓度为1.5和2 mg/L时,藻细胞TP和ATP含量显著降低, MDA含量为对照组的2倍和2.6倍,细胞膜通透性高于对照的1.7倍和2倍。2 mg/L处理组ROS含量显著增加,为对照组的4.0倍,刺激藻细胞产生氧化应激, T-A...

ACUTE TOXIC EFFECT OF ARSENATES ON CHLORELLA VULGARIS

In order to explore the toxicity and mechanism of heavy metals arsenic in aquatic ecosystem, Chlorella vulgaris, a typical phytoplankton indicator species, was used as the experimental object. Different concentrations of As5+ (0, 0.1, 0.5, 1, 1.5 and 2.0 mg/L) were used to study the effects of As5+ on the density, chlorophyll a content, cell membrane permeability, reactive oxygen species (ROS) content, malondialdehyde (MDA) content, total antioxidant capacity (T-AOC), total protein (TP) content, total superoxide dismutase (T-SOD) activity, ATP activity and ultrastructure of C. vulgaris. The results showed that all concentrations of As5+ could inhibit the growth of C. vulgaris within 96h, and the inhibition rate of 2 mg/L treatment group was the highest (52.9%). The IC₅₀ of 96h was 1.94 mg/L. The Chl.a content of algae cells was also inhibited in all treatment groups, among which, the treatment group of 2 mg/L was the lowest which was only 31.4% of the control group. When the concentration of As5+ was 1.5 and 2 mg/L, the content of TP and ATP decreased significantly. The content of MDA was 2 times and 2.6 times higher than that of the control group, and the cell membrane permeability was 1.7 times and 2 times higher than that of the control group. The content of ROS in 2 mg/L treated group increased significantly, which was 4.0 times of that in control group. The activities of T-AOC and T-SOD in algal cells stimulated by oxidative stress were 2.8 times and 1.6 times higher than those in control group. The results of transmission electron microscope showed that the group treated with 2 mg/L As5+ could destroy the internal structure of algae cells, resulting in cytoplasmic vacuolation, lamellar structure fracture of thylakoids and chloroplast structure disorder. The results showed that high concentration of As5+ was destructive to the structure and function of cell membrane and main organelles of C. vulgaris. At the same time, C. vulgaris produced oxidative stress in response to pollutant stress. The concentration of As5+ below 1.5 mg/L had no significant effect on physiological and biochemical indexes of C. vulgaris. This study reveals the physiological and biochemical reactions of the typical indicator species C. vulgaris under As5+ environmental stress, and provides basic data for the remediation of heavy metal pollution in the water environment and the formulation of relevant environmental standards, thereby realizing the sustainable development and utilization of the aquatic ecosystem.