重金属Cu2+,Pb2+和Zn2+胁迫对近江牡蛎(Crassostrea rivularis) SOD活性影响研究

为探讨将近江牡蛎(Crassostrea rivularis)抗氧化酶防御体系参数作为海洋重金属污染生物监测指标可行性,文章在实验室条件下,研究这三种重金属暴露对近江牡蛎(C.rivularis)鳃和消化腺组织SOD活性的诱导作用;实验结果表明:Cu2 ,Pb2 和Zn2 能诱导近江牡蛎(C.rivularis)腮和消化腺SOD的产生,但由于近江牡蛎(C.rivularis)腮和消化腺的结构和功能的不同,在重金属的诱导下,消化腺内的SOD活性要比腮的大;Pb2 和Zn2 诱导近江牡蛎(C.rivularis)鳃和消化腺组织SOD活性变化的剂量-效应均为抛物线型;Cu2 对近江牡蛎(C.rivularis)鳃组织SOD活性诱导曲线不呈抛物线型,而对消化腺组织SOD活性诱导的剂量-效应呈抛物线型;根据对SOD活性影响的强弱,三种重金属对近江牡蛎(C.rivularis)的毒性强弱顺序为Cu2 >Pb2 >Zn2 。在实验室条件下,近江牡蛎(C.rivularis)消化腺组织中的SOD活性可作为养殖水体重金属污染程度监测指标,但应用到实际养殖水体尚须进一步研究。     

壬基酚对赤子爱胜蚓的生态毒理学研究

环境激素对生态的影响越来越受到人们的重视。通过赤子爱胜蚓对壬基酚的滤纸接触法毒性试验,从分子水平揭示环境污染物对蚯蚓组织的毒性影响。在壬基酚对赤子爱胜蚓(Eiseniafoetida)的急性毒性试验中,测得72hLC50为0.908μg/cm2。在系列浓度的壬基酚暴露中,过氧化氢酶(Catalase,CAT),超氧化物歧化酶(Superoxidedismutase,SOD)和谷胱甘肽硫转移酶(GlutathioneS-transferase,GST)的敏感性依次为CAT>SOD>GST。实验结果表明,这三种酶均可作为早期NP污染预警指标。     

有机磷农药对海洋微藻致毒性的生物学研究Ⅰ．四种海洋微藻对久效磷的耐受力与其SOD活性的相关性

本文研究了久效磷农药对扁藻、三角褐指藻、金藻和盐藻的毒性实验。结果表明，四种海洋微藻对久效磷的耐受力依次为：盐藻＞三角褐指藻＞金藻＞扁澡。对微藻细胞内过氧化物歧化酶（ＳＯＤ）活性的测定表明，四种海洋微藻对久效磷的耐受力与其ＳＯＤ活性具相关性，耐受力最强的盐藻其细胞内ＳＯＤ活性较高，并在久效磷的胁迫下保持相对稳定；耐受力较弱的三角褐指藻和金藻其细胞内ＳＯＤ活性随着久效磷浓度的提高逐渐下降；而耐受力弱的扁藻在久效磷胁迫下，其细胞内ＳＯＤ活性迅速下降。因此，可从ＳＯＤ活性及其变化规律上判断久效磷对海洋环境污染的程度以及海洋微藻的耐受力。     

Relationship between metabolic enzyme activities and bioaccumulation kinetics of PAHs in zebrafish (Danio rerio)

Many studies have investigated bioaccumulation and metabolism of polycyclic aromatic hydrocarbons (PAHs) in aquatic organisms. However, lack of studies investigated both processes simultaneously, and the interaction between these two processes is less understood so far. This study investigated the bioaccumulation kinetics of PAHs and metabolic enzyme activities, including total cytochrome P450 (CYPs) and total superoxide dismutase (T-SOD), in zebrafish. Mature zebrafish was exposed to the mixture of phenanthrene and anthracene under constant concentration maintained by passive dosing systems for 16 days. The results showed that PAH concentrations in zebrafish experienced a peak value after exposure for 1.5 days, and then decreased gradually. The bioaccumulation equilibrium was achieved after exposure for 12 days. Both of the uptake rate constants (k_u) and the elimination rate constants (k_e) decreased after the peak value. The variation of PAH concentrations and metabolic enzyme activities in zebrafish had an interactive relationship. CYPs and T-SOD activities increased initially with the increase of PAH concentrations, but decreased to the lowest state when PAH concentrations reached the peak value. When the bioaccumulation equilibrium of PAHs was achieved, CYPs and T-SOD activities also reached the steady state. In general, CYPs and T-SOD activities were activated after exposure to PAHs. The decrease of PAH concentrations in zebrafish after the peak value may be attributed to the great drop of k_u and the variation of CYPs activities. This study suggests that an interactive relationship exists between bioaccumulation kinetics of PAHs and metabolic enzyme activities in aquatic organisms.     

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.     

Acrylamide-induced disturbance of the redox balance in the chick embryonic brain

This study was undertaken to determine the redox balance in the developing brain after exposure to acrylamide (ACR), a potent neurotoxin. The studies were performed using an in ovo chick embryo model. The antioxidant enzymes SOD, GPx, CAT, and reduced glutathione (GSH) were used as indicators of the redox balance. Eggs were injected with ACR doses of 40 mg kg^?1 egg mass (2.4 mg egg^?1) on embryonic day 17 (E17). The activity of the antioxidant enzymes and the concentration of GSH were measured at E17, E18, and E19 in the medulla oblongata, cerebrum, cerebellum, and optic lobe. The results indicated a significant decrease in the GSH concentrations in the optic lobe (E19, E20) and cerebrum (E20) of embryos exposed to ACR. The activities of SOD and GPx were significantly increased in the majority of the examined structures after injection of ACR. CAT activity was completely inhibited in the brains of the embryos exposed to ACR compared to that in the brains of the control embryos. Thus, we concluded that ACR exerts a significant influence on the redox balance in the developing brain by impacting the activity of antioxidant enzymes and the levels of GSH.     

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).     

镉对鲫鱼鳃和肝脏超氧化物歧化酶活性的影响

使用浸浴法以 0 mg/ L、0 .73 mg/ L、1 .46 mg/ L、2 .95 mg/ L 4个镉 (Cd Cl2 · 2 .5H2 O)浓度为丰产鲫 (Carassiusauratus of Penze(♀ )× Cyprinusacutidorsalis(♂ ) )幼鱼染毒 ,测定了 1 4 4 h内鳃及肝组织中超氧化物歧化酶 (SOD)活性的变化。结果表明 ,低浓度组Cd曝露时 ,鲫鱼鳃和肝组织中 SOD活性的变化短时间内不明显 ,但随着处理时间的延长 ,Cd提高了鳃和肝组织中 SOD的活性 ,导致“毒物兴奋效应”。高浓度组 Cd曝露时均抑制了肝和鳃中的 SOD活性 ,其作用随着曝露时间的延长和浓度的升高而增强 ,SOD酶活性降低所造成的活性氧伤害是引起鲫幼鱼死亡的重要原因。肝组织中的 SOD酶活性和敏感性高于鳃 ,这与其执行的生理功能有关     

氧化型染发剂对沙蚕的毒性效应及对部分酶活性的影响

在实验室模拟条件下,研究了氧化型染发剂对双齿围沙蚕(Perinereis aibuhiteusis Grube)的急性毒性效应及不同暴露浓度(0、40、80、160、320mg·L-1)和暴露时间(0、4、6、8、10d)下对其体内乙酰胆碱酯酶(AChE)和超氧化物歧化酶(SOD)活性的影响.结果表明,1)暴露3d后氧化型染发剂对沙蚕的半数致死浓度(LC50)为1849.6mg·L-1;2)沙蚕体内AChE和SOD活性受到氧化型染发剂暴露浓度的显著影响:暴露3d后,随暴露浓度的升高(0～320mg·L-1),AChE和SOD活性均呈先被诱导后逐渐下降的变化趋势;3)沙蚕体内AChE和SOD活性也受到暴露时间的显著影响:40mg·L-1浓度下,随暴露时间的延长(0～10d),SOD活性呈先下降又缓慢上升的趋势,而AChE活性变化没有显著规律;4)通过比较发现,相对于AChE,SOD的活性变化更能反映氧化型染发剂对沙蚕的毒性作用.