Ni2+胁迫对铜绿微囊藻（Microcystis aeruginosa）和集胞藻（Synechocystis sp.）的生长和光合色素的影响(Effects of Nickel on Growth and Photosynthetic Pigments of Microcystis aeruginosa and Synechocystis sp.)

光合作用是蓝藻生长繁殖的生理基础,研究重金属胁迫下蓝藻光合色素的变化和响应,有助于揭示其受害机理.在实验室无菌纯培养条件下,研究了不同浓度Ni2+处理下铜绿微囊藻和集胞藻的生物量和光合色素随时间的变化趋势.结果表明:浓度为5mg·L-1～25mg·L-1的Ni2+对M.aerugonisa的生长有抑制作用,随着处理剂量的增加和处理时间的延长,抑制作用愈加显著;在短时间(24h)内,Ni2+对Synechocystissp.的生长没有显著影响,随胁迫时间延长呈现出抑制作用;Ni2+处理M.aerugonisa至24h及Synechocystis sp.至48h时,藻细胞光吸收能力整体上受到明显抑制;5mg·L-1～25mg·L-1的Ni2+胁迫下,M.aerugonisa和Synechocystis sp.的叶绿素a含量随胁迫时间延长而降低;在叶绿素a(Chla)、藻蓝蛋白(PC)和别藻蓝蛋白(APC)三种光合色素中,藻蓝蛋白(PC)对Ni2+胁迫最为敏感,是Ni2+伤害蓝藻的重要作用位点.Ni2+对M.aerugonisa的抑制作用比Synechocystis sp.更明显.     

二甲苯、蒽、苯并[α]芘对虾夷扇贝幼贝血清SOD、CAT活性的影响

以虾夷扇贝(Mizuhopecten yessoensis)为受试生物,设置3种不同浓度的二甲苯、蒽、苯并[α]芘处理健康的虾夷扇贝,检测血清中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性变化情况,结果发现:0.01~1.0 mg·L~(-1)的二甲苯、0.002~0.2 mg·L~(-1)的蒽、0.001~0.1 mg·L~(-1)的苯并[α]芘处理6、12 h后,虾夷扇贝血清SOD活性升高,处理12 h后对血清SOD活性诱导率均高于处理6 h的;处理6 h后,血清CAT活性降低,而处理12 h后,血清CAT活性升高;具有显著的剂量-效应关系和时效关系,表明二甲苯、蒽、苯并[α]芘对虾夷扇贝具有氧化胁迫作用,可能导致其氧化损伤。相关性分析发现,3种污染物处理6 h后,血清SOD活性与CAT活性变化呈显著负相关;而处理12 h后,血清SOD活性与CAT活性变化呈显著正相关。上述结果为开展二甲苯、蒽、苯并[α]芘对海洋贝类毒性评价提供基础数据。     

成团泛菌(Pantoea agglomerans)对镉胁迫下蒌蒿耐受性的影响

为探讨功能微生物对镉(Cd)胁迫下蒌蒿耐受性的影响,以成团泛菌(Pantoea agglomerans)J2为对象,通过盆栽试验,研究不同Cd处理水平下J2菌对蒌蒿生长、生理、Cd富集转运与根际微生态的影响。结果表明:J2菌可显著促进蒌蒿株高、地上部干重、地下部干重、总生物量及根冠比的增加。在J2菌的作用下,蒌蒿叶绿素a、叶绿素b和总叶绿素含量以及超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性均显著增加,丙二醛(MDA)含量明显减少。J2菌可显著促进蒌蒿对Cd的富集转运,蒌蒿地上部、地下部与总Cd含量均显著增加,地上部生物富集系数(BCF)明显大于地下部,转运系数(TF)相比于对照增加了7.5%~37.4%。J2菌可显著增加蒌蒿根际土壤细菌、放线菌数量及微生物总量,明显减少真菌数量。研究表明成团泛菌J2对蒌蒿生长、生理、Cd富集转运与根际微生态可产生积极影响,在一定程度上可提高蒌蒿植株对Cd的耐受性。     

三邻甲苯磷酸酯对大鼠C6星形胶质细胞的氧化损伤和细胞周期阻滞作用

三邻甲苯磷酸酯(tri-o-cresyl phosphate,TOCP)是一种有机磷酸酯类化合物,具神经毒性作用。研究表明星形胶质细胞是有机磷化合物(organophosphorus compounds,OPs)神经毒性作用的靶点之一。为了探讨TOCP对星形胶质细胞的毒性作用,采用大鼠C6星形胶质细胞分别经0.1、0.3、1.0和3.0 mmol·L-1TOCP染毒处理24 h,应用MTT比色法和乳酸脱氢酶(LDH)活力分析法检测细胞活力,在电子相差显微镜下观察细胞形态,二硫代二硝基苯甲酸(DNTB)比色法测定谷胱甘肽(GSH)含量和谷胱甘肽过氧化物酶(GSH-Px)活性,流式细胞仪检测分析细胞周期。结果显示,经TOCP处理24 h后,大鼠C6星形胶质细胞存活率降低,LDH释放增加,细胞形态也发生了明显的变化。GSH含量和GSH-Px活性降低,G1期细胞数量也逐渐增加。上述结果表明,TOCP对星形胶质细胞具有毒性作用,引起氧化损伤和细胞周期阻滞。     

六溴环十二烷暴露对红鳍笛鲷脑乙酰胆碱酯酶和组织氧化应激的影响及评价

六溴环十二烷(C_(12)H_(18)Br_6,简称HBCD)是近年来在环境中广受关注的优先污染物和高产量化学品。实验室条件下以红鳍笛鲷为研究对象,选取其脑组织非特异性生物标志物超氧化物歧化酶(superoxide dismutase,SOD)、谷胱甘肽巯基转移酶(glutathione S-transferases,GST)和丙二醛(malondialdehyde,MDA)及特异性生物标志物乙酰胆碱酯酶(acetylcholinesterase,ACh E)为指标研究了不同浓度HBCD溶液(8.6μg·L~(-1)、43.0μg·L~(-1)和215μg·L~(-1))暴露96 h对红鳍笛鲷脑组织的氧化损伤和神经毒性效应,同时结合综合生物标志物响应指数(integrated biomarker responses index,IBR),对HBCD造成的胁迫水平和毒性效应进行评价。结果表明:HBCD对红鳍笛鲷脑组织中SOD活性和GST活性表现出不同程度的诱导效应,其中暴露初期SOD活性与HBCD浓度呈正相关,但随暴露时间延长与HBCD浓度呈负相关;HBCD对MDA含量和ACh E活性表现出诱导或抑制且存在剂量依赖性,低浓度组MDA含量表现为先抑制后诱导的过程,ACh E活性表现为先诱导后抑制;中浓度组MDA含量和ACh E均表现为抑制效应;高浓度组MDA含量表现为先诱导后抑制的过程,ACh E活性表现为先抑制后诱导。IBR分析结果表明4种生物标志物对HBCD胁迫的敏感性分别为SODGSTACh EMDA,且中、高浓度组的胁迫效应最明显。     

Thallium(I) and thallium(III) induce apoptosis in isolated rat hepatocytes by alterations in mitochondrial function and generation of ROS

Environmental metal toxins, generated through diverse anthropogenic activities, constitute one of the major contaminants that have led to global dispersion of these toxic metals in the ecosystem. Thallium is one of these widely dispersed metals that produce severe adverse effects on human and biological systems. The influence of thallium(I) and thallium(III) on the early events that trigger apoptosis signaling were examined in freshly isolated rat hepatocytes. In addition, the role of oxidative stress, and mitochondria in the induction of apoptosis were also investigated. Incubation of thallium(I) and thallium(III) with isolated rat hepatocytes generated reactive oxygen species (ROS), collapse of mitochondrial membrane potential, activation of caspases cascade, and appearance of apoptosis phenotype. Mitochondrial permeability transition (MPT) pore sealing agents (cyclosporine A and carnitine) and ATP generators (L-glutamine, fructose, and xylitol) inhibited the activation of caspase-3 and apoptosis, indicating that both the cations activated apoptosis signaling via mitochondrial pathway. Pretreatment of hepatocytes with antioxidants (α-tocopherol or deferoxamine) also blocked caspase-3 activation induced by these cations, suggesting that oxidative stress may be directly involved in a mitochondrial MPT pore opening and activation of caspases cascade. These findings contribute to a better understanding of the mechanisms that mediate thallium-induced apoptosis in isolated rat hepatocytes.     

Ameliorating effects of hormone and Cu on salt stressed Brassica nigra (L.) Koch with reference to growth and biochemical characteristics

The ameliorating effects of exogenous hormone and calcium were investigated in salt-stressed black mustard seedlings (Brassica nigra L.). The seedlings were subjected to various treatments: control (nutrient solution), salt stress, kinetin/abscisic acid (ABA)/calcium chloride (CaCl₂). Sodium chloride (NaCl) inhibited shoot length (45–55%) and root (<75%). Further, alterations in superoxide dismutase and catalase activities were consistent with changes in levels of reactive oxygen species and malondialdehyde (MDA). The beneficial effects of ABA and CaCl₂ in ameliorating salt stress may be attributed to the reduction of membrane peroxidation and increased glutathione (GSH) levels. These observations suggest that oxidative stress resulting from salt stress in B. nigra may result in production of antioxidative enzymes to counteract oxidative damage, and the enzymes may contribute to the ability of B. nigra to survive adverse conditions. Data indicate that hormone and ion in the order of kinetin > ABA > calcium alleviate the adverse impact of salt on B. nigra.     

Biosorption of Cu (II) ions by indigenous copper-resistant bacteria isolated from polluted coastal environment

The concentrations of copper in water and sediment samples of Cuddalore coastal area, Tamil Nadu, India were examined. The isolation, characterization, screening, and metal sorption capabilities of copper-resistant bacteria (CURB) also were investigated. Biosorption capabilities and growth time varied among the resistant isolates. All isolates reduced more than 80% of copper from copper-treated broth. However, Bacillus cereus CURB-4 strain absorbed more copper ions (99.9%) than other resistant isolates. Changes in structural group position and synthesis of extracellular polysaccharides (EPS) of CURB-4 strain under copper stress and controlled conditions also were examined. Under copper stress condition, CURB-4 produced more EPS (71 ± 0.6%) compared to control conditions (66 ± 0.4%). Fourier transform infrared spectroscopy revealed that the changes in functional group position of EPS were observed in stressed condition. Overall, synthesis of EPS in bacteria is a protective barrier against environmental stress.     

Protective role of L-ascorbic acid against cypermethrin-induced oxidative stress and lipid peroxidation in Wistar rats

Cypermethrin is a synthetic pyrethroid insecticide used for pest control in agriculture and as an acaricide in man and animals. This study was undertaken with the objective to investigate the propensity of cypermethrin to induce oxidative stress in rats following repetitive dermal exposure and its possible attenuation by L-ascorbic acid. Results obtained showed that cypermethrin significantly (p < 0.05) increased malonaldehyde levels, activity of catalase in rat erythrocytes and plasma protein levels. Whereas, activities of glutathione (GSH), glutathione peroxidase (GSH-Px), and superoxide dismutase (SOD) were significantly (p < 0.05) reduced in the cypermethrin exposed rats as compared to the control. Supplementation of L-ascorbic acid in cypermethrin-exposed rats decreased lipid peroxidation of erythrocytes, total plasma protein and catalase activity significantly (p < 0.05) compared to non-cypermethrin-exposed group. However, L-ascorbic acid did not alleviate the negative effects of cypermethrin on the activities of SOD and GSH. This study revealed that the presence of L-ascorbic acid diminishes the adverse effects of cypermethrin on some oxidative stress parameters.