Growth, photosynthesis and antioxidant responses of two microalgal species, Chlorella vulgaris and Selenastrum capricornutum, to nonylphenol stress

The effect of nonylphenol (NP) on growth, photochemistry and biochemistry of two green microalgae, Chlorella vulgaris and Selenanstrum capricornutum, and their ability to degrade NP were compared. The 96 h EC₅₀ of C. vulgaris and S. capricornutum were greater than 4.0 and 1.0 mg L⁻¹ NP, respectively, suggesting that the former species was more tolerant to NP. Both microalgae acclimated to NP stress through down-regulating their photosynthetic activities, including antenna size (chlorophyll a content), maximal photochemistry (Fv/Fm) and the light absorbed by PSII (ABS/CS₀), but the dissipation of energy from reaction centres (DI₀/RC) increased with the increase of NP concentrations. In C. vulgaris, the changes of these parameters were more significant than in S. capricornutum and recovered completely after a 96 h exposure. The antioxidant responses, such as GSH content, CAT and POD activities in C. vulgaris increased with the increase of NP concentrations after a 24 h exposure, but these changes disappeared with exposure time and recovered to the control levels after 96 h. In S. capricornutum, although GSH content, CAT and POD activities also increased when exposed to low- to moderate-NP concentrations, these values were significantly reduced at a high concentration (4 mg L⁻¹) even after a 96 h exposure, indicating its antioxidant responses were significantly delayed. It is clear that the more NP-tolerant species, C. vulgaris, acclimated better with a faster recovery of its photosynthetic activity from the NP-induced damage, and exhibited more efficient and rapid responses to NP-induced oxidative stress. C. vulgaris also had a higher NP degradation ability than S. capricornutum.     

PCDD/Fs-induced oxidative damage and antioxidant system responses in tobacco cell suspension cultures

Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) are ubiquitous contaminants and can be considerably accumulated by natural plants. In order to elucidate the biochemical and physiological responses of plant to PCDD/Fs, tobacco Bright Yellow-2 (BY-2) cells were selected as model plant and treated with time- and concentration-dependent PCDD/Fs. The toxic effect and oxidative stress caused by PCDD/Fs were evident, which could be indicted by the reduction in fresh mass, the increase in malondialdehyde (MDA) content, and the damage of tobacco cell ultrastructure. PCDD/Fs tolerance was correlated with changes in antioxidant system and hormones of tobacco cells. Superoxide dismutase (SOD) and peroxidase (POD) exhibited peak enzyme activities at the PCDD/Fs concentration of 1000 ng WHO₉₈-TEQ g⁻¹ fresh weight. Glutathione reductase (GR) enzyme activity increased monotonically at high level PCDD/Fs, but the activity of catalase (CAT) was only slightly affected at all treatment. Meanwhile, the exposure to PCDD/Fs resulted in the changes of hormones content. With the increase of exposure concentration of PCDD/Fs, the levels of indole-3-acetic acid (IAA) and abscisic acid (ABA) increased, whereas the concentration of jasmonates (JAs) decreased. The above results suggest that tobacco cells had the ability to cope with the oxidative stress induced by low concentration of PCDD/Fs through increasing the activities of antioxidant enzymes and alternating plant hormones levels. However, oxidative stress and toxicity would burst out when plant cells were exposed to the high levels of PCDD/Fs.     

Differential physiological,ultramorphological and metabolic responses of cotton cultivars under cadmium stress

Cadmium (Cd) stress may cause serious physiological, ultramorphological and biochemical anomalies in plants. Cd-induced physiological, subcellular and metabolic alterations in two transgenic cotton cultivars (BR001, GK30) and their parent line (Coker 312) were evaluated using 10, 100 and 1000 μM Cd. Germination, fresh biomass of roots, stems and leaves were significantly inhibited at 1000 μM Cd. Root volume tolerance index significantly increased (124.16%) in Coker 312 at 1000 μM Cd. In non-Cd stressed conditions, electron micrographs showed well-configured root meristem and leaf mesophyll cells. At 1000 μM Cd, greater ultramorphological alterations were observed in BR001 followed by GK30 and Coker 312. These changes were observed in nucleus, vacuoles, mitochondria and chloroplast. Dense precipitates, probably Cd, were seen in vacuoles, which were also attached to the cell walls. A considerable increase in number of nuclei, vacuoles, starch granules and plastoglobuli was observed in the electron micrographs of both roots and leaves at 1000 μM Cd. MDA contents were higher in roots of BR001 at 1000 μM Cd. Mean values of SOD activity in leaves of both BR001 and GK30 at 1000 μM Cd significantly increased as compared to the controls. POD activity in roots of BR001 and Coker 312 was greater at all Cd (10, 100, 1000 μM) levels over the control. Regarding APX, highest percent increase (71.64%) in roots of GK30 at 1000 μM Cd was found. Non-significant differences in CAT activity were observed at all levels of Cd stress in leaves of BR001 and GK30. Both transgenic cotton cultivars and their parental line invariably responded towards Cd stress. However, Coker 312 showed Cd-resistant behavior as compared to its progeny lines (BR001 and GK30).     

镉在日本无刺楤木叶片的积累与对其抗氧化系统的影响

为考察镉对日本无刺楤木(Aralia elata var. inermis)生长及品质安全性的影响,采用生物盆栽法研究镉处理对不同生长期楤木叶片抗氧化系统影响及与镉含量关系。结果表明:展叶末期楤木叶片镉含量较少,镉对楤木叶片抗氧化能力有促进作用,随着处理量增加,叶片过氧化物酶(POD)活性、叶绿素含量先增大后减小,镉对过氧化氢酶(CAT)活性影响较强,可使其降至对照的30%,丙二醛(MDA)含量呈一定的先下降后上升的变化。生长中期POD活性达整个生长期最低;随着镉处理量增加,CAT活性先增强后减弱,但明显高于对照;叶绿素含量降幅各生长期最大,最低为对照69.1%;MDA含量则有显著增加。落叶初期叶片镉含量达到同处理最大;随着镉处理量的增加,POD活性持续减弱,CAT活性先增强后减弱,所受影响小于生长中期;叶绿素含量持续下降;落叶初期MDA含量在低量镉处理中降低,高量镉处理下继续升高。     

人工湿地处理污水时水生植物形态和生理特性对污水长期浸泡的响应

主要比较了污水和净水培养水生植物(芦苇、香蒲)形态特征的改变,测定了污水和净水培养的水生植物体内(根、叶片)过氧化物酶(POD)、过氧化氢酶(CAT)的活性,分析判断了水生植物对长期污水浸泡所采取的响应的途径和方式.结果表明,与天然净水培养的芦苇相比,长期污水浸泡致使芦苇的植株高度显著变小,平均值之差为71.1cm;芦苇叶片长度显著减小,叶片长度平均值之差为11.3 cm,最大叶片宽度减小,叶片最大宽度平均值之差为0.62cm;植株密度明显增大,增幅达4倍以上.长期污水浸泡显著影响了香蒲根部POD活性,使其比净水培养高73.51U·g-1·min-1;污水浸泡对芦苇和香蒲叶片CAT活性影响显著,污水培养芦苇和香蒲的叶片CAT活性分别较净水培养芦苇和香蒲低0.068、0.1071mg·g-1·min-1.     

模拟N、P污水对水稻幼苗过氧化物酶和超氧化物歧化酶的影响

以水稻为材料，研究了不同浓度的模拟Ｎ、Ｐ污水对幼苗过氧化物酶（ＰＯＤ，ＥＣ１．１１．１．７）和超氧化物歧化酶（ＳＯｏＤ，ＥＣ１．１５．１．１）及其同工酶等的影响，结果表明：在总氮浓度（Ｎｒ）为０─９０ｍｇ／Ｌ和总磷浓度（Ｐ＿Ｔ）为０─９ｍｇ／Ｌ范围内，ＰＯＤ与Ｎ、Ｐ浓度呈正相关，Ｎ＿Ｔ超过９０ｍｇ／Ｌ和Ｐ＿Ｔ超过９ｍｇ／Ｌ这一阈值后呈下降趋势，ＮＴ在０─１２０ｍｇ／Ｌ和Ｐ＿Ｔ在０─１２ｍｇ／Ｌ范围内，ＳＯＤ，丙二醛（ＭＤＡ）与Ｎ、Ｐ浓度呈显著正相关；Ｎ、Ｐ能诱导产生新的同工酶带，苗高、可溶性蛋白分别与Ｎ、Ｐ浓度呈显著负相关．     

久效磷对海洋微藻毒性机理的初步研究Ⅲ.超氧化物歧化酶和过氧化物酶活性的变化

报道了久效磷对３种海洋微藻细胞内２种清除活性氧的关键性酶———超氧化物歧化酶和过氧化物酶活性的影响．结果显示：１在久效磷的胁迫下，扁藻和三角褐指藻细胞的超氧化物歧化酶（ＳＯＤ）活性均表现出下降的总变化趋势，而叉鞭金藻细胞的ＳＯＤ活性时而上升，时而下降，在整个胁迫过程中呈现出无规律性的变化．２随着久效磷胁迫时间的延长，３种微藻细胞的过氧化物酶活性均逐渐下降，表现出相同的变化规律性．这说明不同的藻种，久效磷对其细胞内酶活性的影响不尽相同．推测超氧化物歧化酶和过氧化物酶（ＰＯＤ）活性的降低是微藻细胞内过量产生活性氧，进而引起藻细胞膜脂过氧化伤害的主要原因之一．     

水体中Cu2+和Cd2+污染对育珠蚌肝脏中3种酶的影响

选取两种水体中常见的重金属污染离子(Cu^2 和Cd^2 )，按一定的浓度梯度配制成溶液，并以此溶液饲养育珠蚌一定时间后，测定两种离子对育珠蚌肝脏中的酯酶(EST)、过氧化物酶(POD)、超氧化物歧化酶(SOD)活性的影响．结果表明，低浓度的重金属离子可以诱导3种酶活性的升高，而高浓度的离子则抑制酶的活性．同工酶电泳检测显示，高浓度的离子导致EST同工酶谱减少一条谱带，低浓度的离子则诱导产生新的SOD同工酶类型，但两种离子均未对POD同工酶谱产生影响．图6参10     

Hg2+胁迫下两优培九和武运粳7号水稻幼苗抗性差异的研究

以三叶期的水稻幼苗为材料 ,比较了Hg2 污染对杂交稻两优培九和常规稻武运粳 7号的叶绿素含量、类囊体膜光系统Ⅰ (PSⅠ )和光系统Ⅱ (PSⅡ )电子传递活性、细胞膜透性、过氧化物酶 (POD)、过氧化氢酶 (CAT)活性和脯氨酸含量的影响。结果表明 ,随着Hg2 处理浓度的增加 ,两优培九和武运粳 7号的叶绿素含量、PSⅠ和PSⅡ的电子传递活性降低 ,而 2者的细胞膜透性、脯氨酸含量升高 ,两优培九的CAT活性、武运粳 7号的POD和CAT活性呈现先升后降的趋势 ,但两优培九的POD活性则呈现升高的趋势。两优培九对Hg2 污染的抗性明显大于武运粳 7号。     

Cr^6＋对3种玉米品种的生理特性影响

为了研究不同剂量下Cr6＋对于三种玉米（Zea mays L.）种子的毒害效应,进一步探究长期堆放铬渣的土壤对周围环境的污染程度以及对生态环境的潜在影响.选取三种不同品种的玉米,随机分为对照组以及1×10^-4、5×10^-4、1×10^-3 mol·L^-1,5×10^-3、1×10^-2 mol·L^-1 实验剂量组,探究Cr6＋对三种不同品种玉米种子的毒害效应.将种子于实验室条件下常规培养后,分别测定不同Cr^6＋胁迫剂量下,三种玉米种子（郑单958,强盛31,农大108）的生长状况,株高、根长、鲜物质量和干物质量以及胁迫前后超氧化物歧化酶（SOD）、过氧化物酶（POD）以及丙二醛（MDA）的含量变化.对不同剂量下Cr^6＋对三种玉米的生理特性影响进行比较研究.结果表明：5 种不同浓度的Cr^6＋溶液对玉米种子进行胁迫后,三种玉米的生长均受到了-定程度的抑制,玉米幼苗株高、根长、鲜物质量和干物质量均呈下降趋势.在低剂量1×10^-4 mol·L^-1 时,即产生显著影响（P〈0.05）,且胁迫剂量越大,对玉米种子生长产生的抑制作用越强.三种不同的玉米种子体内均产生了Cr^6＋富集现象,且随着染毒剂量的增加,玉米体内富集量增加,细胞叶绿素含量和叶绿素a/b 比值降低,三种玉米品种幼苗POD 活性、SOD 活性以及MDA 含量均随暴露浓度增加而增加.在Cr^6＋暴露剂量为最大剂量1×10^-2 mol·L^-1 时,POD 活性、SOD 活性与MDA含量均增加至最大值.各剂量下,均有显著性变化（P〈0.05）产生.由此可见,不同剂量的Cr^6＋对于三种玉米种子均会产生-定的毒害效应,对玉米的生长产生不良影响.