磺化石墨烯对小麦幼苗生长及生理生化指标的影响

随着石墨烯生产量和使用量的不断增大,其对生态环境的风险逐渐引起了环境学家的关注。采用水培试验,探究了磺化石墨烯(SGO)对小麦幼苗的生长、抗氧化酶活性及脂质过氧化的影响。结果表明:在培养10 d后,低浓度磺化石墨烯对小麦根系的生长有显著促进作用(P0.05),200 mg·L-1浓度处理与对照处理相比提高了84.3%,随着浓度增加促进作用逐渐减弱,1 000 mg·L-1时与对照相比提高了19.9%。但对小麦地上部的生长没有影响。磺化石墨烯处理的小麦幼苗根系和叶片组织中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)及丙二醛(MDA)都呈现先下降后上升的趋势。当磺化石墨烯浓度低于200 mg·L-1时,处理组小麦抗氧化酶的活性及MDA含量相对于对照处理大都有所降低,说明低浓度时磺化石墨烯没有对小麦的生长产生氧化胁迫,这与磺化石墨烯可能具有一定的抗氧化能力有关,而高浓度时由于产生氧化胁迫使各项生理生化指标逐渐上升。本实验结果为石墨烯材料对植物的毒理学研究提供了基础数据。     

Imidacloprid induced alterations in oxidative stress,biochemical, genotoxic,and immunotoxic biomarkers in non-mammalian model organism Galleria mellonella L. (Lepidoptera: Pyralidae)

Imidacloprid (IMI), a neonicotinoid insecticide, is widely used to control pests in agriculture. We investigated the changes in antioxidant enzyme activities, lipid peroxidation levels, biochemical effects, genotoxic effect, and immunotoxic effect of sublethal doses (0.25, 0.50, 0.75, and 1.00?µg) of IMI at different time periods (24, 48, 72, and 96?h) on a model organism, Galleria mellonella L. The results indicated that there were dose-dependent increases in both antioxidant enzyme activities (SOD and CAT) and MDA levels. Protein content was not affected by IMI at 24th and 48th, whereas it was decreased by the highest dose of IMI (1.00?µg) at 72nd and 96th h. Lipid and carbohydrate contents were reduced with increasing doses of IMI. Micronucleus frequency significantly increased in all IMI doses. All IMI doses caused a significant decrease in THC at 24th, 48th, and 72nd h. Our results can help to illustrate the effects of IMI in target organisms and indirectly may aid to discover potential risk of it on nontarget organisms. Future studies, at molecular levels, will be helpful in understanding the mechanism of action of IMI on these biomarkers.     

Impact of nano-CuO stress on rice (Oryza sativa L.) seedlings

Indiscriminate release of metal oxide nanoparticles (NPs) into the environment due to anthropogenic activities has become a serious threat to the ecological system including plants. The present study assesses the toxicity of nano-CuO on rice (Oryza sativa cv. Swarna) seedlings. Three different levels of stress (0.5 mM, 1.0 mM and 1.5 mM suspensions of copper II oxide, <50 nm particle size) were imposed and seedling growth performance was studied along control at 7 and 14 d of experiment. Modulation of ascorbate–glutathione cycle, membrane damage, in vivo ROS detection, foliar H₂O₂ and proline accumulation under nano-CuO stress were investigated in detail to get an overview of nano-stress response of rice. Seed germination percentage was significantly reduced under stress. Higher uptake of Evans blue by nano-CuO stressed roots over control indicates loss of root cells viability. Presence of dark blue and deep brown spots on leaves evident after histochemical staining with NBT and DAB respectively indicate severe oxidative burst under nano-copper stress. APX activity was found to be significantly increased in 1.0 and 1.5 mM CuO treatments. Nevertheless, elevated APX activity might be insufficient to scavenge all H₂O₂ produced in excess under nano-CuO stress. That may be the reason why stressed leaves accumulated significantly higher H₂O₂ instead of having enhanced APX activity. In addition, increased GR activity coupled with isolated increase in GSH/GSSG ratio does not seem to prevent cells from oxidative damages, as evident from higher MDA level in leaves of nano-CuO stressed seedlings over control. Enhanced proline accumulation also does not give much protection against nano-CuO stress. Decline in carotenoids level might be another determining factor of meager performance of rice seedlings in combating nano-CuO stress induced oxidative damages.     

The impact of ambient ozone on mountain spruce forests in the Czech Republic as indicated by malondialdehyde

Malondialdehyde (MDA), a product of lipid peroxidation and biomarker of oxidative stress, is measured over the long term in spruce Picea abies needles under real conditions in three Czech mountain border areas. The trends presented collate the MDA content in spruce needles with ambient ozone, temperature and precipitation as casual, and defoliation as a subsequent factor for the period 1994-2006. We have found the overall decreasing trends in MDA and defoliation. The highest MDA and defoliation are recorded in the Jizerske, the lowest in the Krusne hory Mts. Out of the examined variables the MDA is predicted best by mean temperature in vegetation season, median of O₃ concentrations and AOT40; these three variables account for 34% of MDA1 and 36% of MDA2 variability. Our hypothesis that higher ambient O₃ exposure results in higher MDA contents in P. abies needles under real conditions has not been approved.     

Can phosphate compounds be used to reduce the plant uptake of Pb and resist the Pb stress in Pb-contaminated soils？

The effects of di erent phosphate-amendments on lead (Pb) uptake, the activities of superoxide dismutase (SOD) and the level of malondialdehyde (MDA) in cauliflower (Brassica oleracea L.) in contaminated soils with 2500, or 5000 mg P2O5/kg soil of hydroxyapatite (HA), phosphate rock (PR), single-superphosphate (SSP) and the mix of HA/SSP (HASSP) were evaluated in pot experiments. Results showed that the Pb concentrations in shoots and roots decreased by 18.3%–51.6% and 16.8%–57.3% among the treatments respectively compared to the control samples. The e ciency order of these phosphate-amendments in reducing Pb uptake was as follows: HASSPt HA > SSP t PR.With the addition of SSP, HA and the mix of HA/SSP, the SOD activity in shoot was reduced markedly (P < 0.05) compared with that in the control group. For example, the SOD activities in shoot by the treatments of HASSP, SSP, and HA in 5000 mg P2O5/kg were found to be only 51.3%, 56.2%, and 56.7%, respectively. Similar e ects were also observed on the level of MDA in the shoots with a decrease in 24.5%–56.3%. The results verified the inference that phosphate compounds could be used to reduce the plant uptake of Pb and resist the Pb stress in the plant vegetated in Pb-contaminated soils.     

三株溶藻菌对水华鱼腥藻抗氧化酶活性的影响

研究了三株溶藻菌L7,L8和L18的溶藻活性代谢产物对水华鱼腥藻（Anabaena flos—aquae）超氧化物歧化酶（Superoxide dismutase,SOD）比活性、过氧化氢酶（Catalase,CAT）比活性和膜脂过氧化产物丙二醛（Malondialdehyde,MDA）浓度的影响,试图从藻类的抗氧化酶系的变化揭示溶藻活性代谢产物的溶藻机制。在L7,L8和L18的溶藻活性代谢产物胁迫下,水华鱼腥藻的SOD比活性显著升高,MDA浓度急剧上升。加入L18的溶藻活性代谢产物后,水华鱼腥藻的CAT比活性显著高于空白组,L7和L8的溶藻活性代谢产物对水华鱼腥藻的CAT比活性无显著影响。     

镉和乙草胺复合污染对玉米生理特性的影响

采用盆栽试验,研究了镉与乙草胺复合污染对玉米幼苗MDA含量和抗氧化酶活性的影响。结果表明,镉单独处理,低浓度下MDA的含量变化不大,当镉浓度大于30 mg/kg时,MDA的含量急剧上升;超氧化物歧化酶SOD、CAT在浓度为30 mg/kg时活性达到最高,之后随浓度的增大,其活性逐渐降低;POD的活性随着镉浓度的增大逐渐升高,且100 mg/kg时达到最高。镉与乙草胺复合处理,低镉浓度下MDA的含量与对照组CK相比差异显著,处理浓度越大,MDA含量越高;SOD、CAT的活性变化趋势与单镉处理时相类似,但变化幅度更加明显;POD的活性则随着浓度的增大继续升高。镉与乙草胺复合处理对玉米幼苗的毒害程度要大于单镉处理,并且施加乙草胺的浓度越大,玉米受毒害程度越深。     

非潮汐淹水对白骨壤膜脂过氧化系统的影响

通过室内模拟非潮汐淹水,探索不同淹水水位条件下,红树植物白骨壤(A.marina(Forsk.)Vierh).超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、丙二醛(MDA)随时间的变化情况。结果表明,经历第二个淹水周期后,较第一个周期各梯度,白骨壤超氧化物歧化酶活性(SOD)从高到低排序不变,过氧化氢酶活性(CAT)、丙二醛的量(MDA)也表现出相同的规律。本研究结论为红树植物在人工非潮汐生境下,红树林造林的关键技术之一——淹水水位的控制提供了数据参考。     

Subcellular distribution and toxicity of cadmium in Potamogeton crispus L

The submerged macrophyte Potamogeton crispus L. was subjected to varying doses of cadmium (0, 20, 40, 60 and 80 μM) for 7 d, and the plants were analyzed for subcellular distribution of Cd, accumulation of mineral nutrients, photosynthesis, oxidative stress, protein content, and ultrastructural distribution of calcium (Ca). Leaf fractionation by differential centrifugation indicated that 48-69% of Cd was accumulated in the cell wall. At all doses of Cd, the levels of Ca and B rose and the level of Mn fell; the levels of Fe, Mg, Zn, Cu, Mo, and P rose initially only to decline later. Exposure to Cd caused oxidative stress as evident by increased content of malondialdehyde and decreased contents of chlorophyll and protein. Photosynthetic efficiency, as indicated by the quenching of chlorophyll a fluorescence (Fv/Fm, Fo and Fm), decreased significantly, the extent of decrease being directly proportional to the concentration of Cd. Increased amounts of precipitates of calcium were noticed in the treated plants, located either outside the cell membrane or in chloroplasts, mitochondria, the nucleus, and the cytoplasm whereas control plants showed small deposits of the precipitates around surface of the vacuole membrane and in the intercellular space but rarely in the cytoplasm. Photosynthetic efficiency and oxidative stress could be used as indicators of physiological end-points in determining the extent of Cd phytotoxicity.