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81.
Alma Hortensia Serafín Muoz Kazimierz Wrobel J. Felix Gutierrez Corona Katarzyna Wrobel 《Mycological Research》2007,111(5):626-632
The effect of two inorganic selenium forms has been investigated in the mycelia of Pleurotus ostreatus exposed to cadmium and silver salts in the shaken cultures. The degree of toxicity was assessed by the determination of malondialdehyde (MDA; a common biomarker of lipid peroxidation). The mycelia were exposed to one element form (up to 5 mg l−1) and also to the following combinations: cadmium(II) + selenium(IV); cadmium(II) + selenium(VI); silver(I) + selenium(IV); silver(I) + selenium(VI). The concentrations of cadmium, silver, selenium, and MDA were assessed in the mixed cytosol and cell membrane fractions (CCM). A positive correlation between MDA and cadmium was found in the CCM (β = 0.7775, P = 0.0001), whereas the effect of silver was less significant (β = 0.4642, P = 0.039). These results indicate that silver(I) and cadmium(II) have different capacities to induce lipid peroxidation in P. ostreatus. The protective role of selenium against metal-induced oxidative damage was found to be dependent on the oxidation state of the element form in the growth medium. The strongest beneficial effect was observed in mycelia exposed to cadmium(II) + selenium(IV) (inverse correlation between MDA and selenium in the CCM: β = −0.7129, P = 0.009) and it has been ascribed to a lower incorporation of the toxic metal and/or to possible intracellular interaction between selenium and cadmium. Under exposure to silver(I), the protective effect of selenium(IV) was less noticeable (correlation between MDA and selenium in the CCM; β = −0.6068, P = 0.036); in the presence of selenium(VI), no beneficial effect was observed. 相似文献
82.
Investigating the mechanisms underlying phytoprotection by plant growth‐promoting rhizobacteria in Spartina densiflora under metal stress 下载免费PDF全文
K. Paredes‐Páliz R. Rodríguez‐Vázquez B. Duarte M. A. Caviedes E. Mateos‐Naranjo S. Redondo‐Gómez M. I. Caçador I. D. Rodríguez‐Llorente E. Pajuelo 《Plant biology (Stuttgart, Germany)》2018,20(3):497-506
- Pollution of coasts by toxic metals and metalloids is a worldwide problem for which phytoremediation using halophytes and associated microbiomes is becoming relevant. Metal(loid) excess is a constraint for plant establishment and development, and plant growth promoting rhizobacteria (PGPR) mitigate plant stress under these conditions. However, mechanisms underlying this effect remain elusive. The effect of toxic metal(loid)s on activity and gene expression of ROS‐scavenging enzymes in roots of the halophyte Spartina densiflora grown on real polluted sediments in a greenhouse experiment was investigated.
- Sediments of the metal‐polluted joint estuary of Tinto and Odiel rivers and control, unpollutred samples from the Piedras estuary were collected and submitted to ICP‐OES. Seeds of S. densiflora were collected from the polluted Odiel marshes and grown in polluted and unpolluted sediments. Rhizophere biofilm‐forming bacteria were selected based on metal tolerance and inoculated to S. densiflora and grown for 4 months. Fresh or frozen harvested plants were used for enzyme assays and gene expression studies, respectively.
- Metal excess induced SOD (five‐fold increase), whereas CAT and ascorbate peroxidase displayed minor induction (twofold). A twofold increase of TBARs indicated membrane damage. Our results showed that metal‐resistant PGPR (P. agglomerans RSO6 and RSO7 and B. aryabhattai RSO25) contributed to alleviate metal stress, as deduced from lower levels of all antioxidant enzymes to levels below those of non‐exposed plants. The oxidative stress index (OSI) decreased between 50 and 75% upon inoculation.
- The results also evidenced the important role of PAL, involved in secondary metabolism and/or lignin synthesis, as a pathway for metal stress management in this halophyte upon inoculation with appropriate PGPR, since the different inoculation treatments enhanced PAL expression between 3.75‐ and five‐fold. Our data confirm, at the molecular level, the role of PGPR in alleviating metal stress in S. densiflora and evidence the difficulty of working with halophytes for which little genetic information is available.
83.
目的:观察不同低氧时间大鼠颏舌肌肌纤维类型的变化。方法:建立低氧模型,血气分析证实模型成功建立。在低氧不同时间点分别取低氧组和正常组雄性SD大鼠颏舌肌进行HE染色,肌球蛋白ATP酶组织化学染色和RT-PCR检测肌纤维类型的变化。结果:血气分析结果证实低氧组氧分压与血氧饱和度较对照组发生明显下降(P0.05)。低氧1周组、2周组、3周组、4周组较正常组氧分压下降至55.04±2.31 mm Hg,52.69±1.51 mm Hg,49.80±1.39 mm Hg,50.11±3.02 mm Hg(P0.05);血氧饱和度下降至77.51±1.81%,70.13±2.90%,74.20±1.95%,74.97±2.36%(P0.05)。HE染色和肌球蛋白ATP酶组织化学染色法显示低氧2、3、4周组Ⅱ型肌纤维所占比例较相应正常组依次升高:45.92±1.8%,57.44±2.1%,56.89±2.6%,在第三周时达到顶峰(P0.05)。RT-PCR结果也同样验证了这一规律。结论:随着低氧活动的进行,颏舌肌肌纤维类型发生有规律的转化,从而影响着肌肉的功能。 相似文献
84.
Fereydoun Ghazban Abdolhossien Parizanganeh Abbasali Zamani Behzad Taghilou 《Soil & Sediment Contamination》2015,24(2):172-190
The concentrations of selected heavy metals in sediments and waters in Baychebagh copper mine were determined using ICP-OES. Except for Co, the average concentrations of Cd, Cu, Pb, and Zn in sediments from the Ghalechay River in the district exceed the world-average shale and continental upper crust value. Enrichment factors for Pb, Cu, and Cd were significantly enriched in sediments, indicating environmental contamination. Geoaccumulation index calculated for different sampling stations indicates that the sediments are unpolluted with respect to Co and Zn while unpolluted to moderately polluted with Cu and highly polluted with Pb and Cd. The Sediment Quality Guidelines (SQGs) suggest that Cd and Pb may pose the highest risk for the environment. Sequential extraction analyses of sediments revealed that Cu, Co, Pb, and Zn bound to extractable, carbonate, reducible and oxidizable fractions are lower than residual fraction. About 10% of the total Pb was associated with the exchangeable fraction, indicating remobilization, while Cd (89%), Pb (73%) Co (58%), Cu (76%), and Zn (68%) closely associated with the residual and oxidizable fractions, resulting in their environmental immobility. The residual forms are not expected to be released under normal conditions in the river and could be considered an inert phase. 相似文献
85.
Competitive adsorption of Pb, Cd and Zn ions onto Eichhornia crassipes in binary and ternary systems
A batch sorption technique was used to study the biosorption of Pb2+, Cd2+ and Zn2+ ions onto the vastly abundant water hyacinth weed, Eichhornia crassipes biomass in binary and ternary systems at a temperature of 30 °C and pH 4.84. Mutual interference effects were probed using equilibrium adsorption capacity ratios, , where the prime indicates the presence of one or two other metal ions. The combined action of the metals was found to be antagonistic, and the metal sorption followed the order Pb2+ Cd2+ Zn2+. The behaviour of competitive biosorption for Pb–Cd and Pb–Zn combinations were successfully described by the Langmuir Competitive Model (CLM), whilst the model showed poor fitting to the Cd–Zn data. In conclusion, Pb2+ ions could still be effectively removed from aqueous solution in the presence of both Cd2+ and Zn2+ ions, but removal of the Cd2+ and Zn2+ ions would be suppressed in the presence of Pb2+. 相似文献
86.
The presence of toxic heavy metals in natural environments entails a potential health hazard for humans. Metal contaminants in these environments are usually tightly bound to colloidal particles and organic matter. On the other hand, the potential of these metals towards chelation by different chelating agents presents a good characteristic for their removal from the environment. On this basis, two chitosan/anionic surfactant complexes were prepared and evaluated for their ability to remove heavy metals from aqueous solutions. The experimental results of the uptake of metal ions including Cu2+, Sn2+, Co2+ and Ni2+ are reported in this study. The results show that modified chitosan with short‐spacer group cross‐linkers has a higher potential for heavy metal uptake than long‐chain cross‐linker‐modified chitosan. Also, increasing the electronegativity of the heavy metals increases their uptake from the medium. Increasing the time of exposure of the heavy metals to the modified polymer increases the efficiency of the metal uptake process. 相似文献
87.
Cell suspension cultures of red spruce (Picea rubens Sarg.) were selected to study the effects of cadmium (Cd) and zinc (Zn) on phytochelatins (PCs) and related metabolites after
24 h exposure. The PC2 and its precursor, γ-glutamylcysteine (γ-EC) increased two to fourfold with Cd concentrations ranging from 12.5 to 200 μM
as compared to the control. However, Zn-treated cells showed a less than twofold increase in γ-EC and PC2 levels as compared to the control even at the highest concentration of 800 μM. In addition, unidentified higher chain PCs
were also found in both the Cd and Zn treated cells and they increased significantly with increasing concentrations of Cd
and Zn. The cellular ratio of PC2 : Cd or Zn content clearly indicated that Cd (with ratios ranging from 0.131 to 0.546) is a more effective inducer of PC2 synthesis/accumulation than Zn (with ratios ranging from 0.032 to 0.102) in red spruce cells. A marginal decrease in glutathione
(GSH) was observed in both Cd and Zn treated cells. However, the GSH precursor, cysteine, declined twofold with all Cd concentrations
while the decrease with Zn was 1.5–2-fold only at the higher treatment concentrations of Zn as compared to control. In addition,
changes in other free amino acids, polyamines, and inorganic ions were also studied. These results suggest that PCs and their
biosynthetic intermediates play a significant role in red spruce cells protecting against Cd and Zn toxicity. 相似文献
88.
Susan E. Crow Christopher W. Swanston Kate Lajtha J. Renée Brooks Heath Keirstead 《Biogeochemistry》2007,85(1):69-90
Soil organic matter (SOM) is often separated by physical means to simplify a complex matrix into discrete fractions. A frequent
approach to isolating two or more fractions is based on differing particle densities and uses a high density liquid such as
sodium polytungstate (SPT). Soil density fractions are often interpreted as organic matter pools with different carbon (C)
turnover times, ranging from years to decades or centuries, and with different functional roles for C and nutrient dynamics.
In this paper, we discuss the development and mechanistic basis of common density-based methods for dividing soil into distinct
organic matter fractions. Further, we directly address the potential effects of dispersing soil in a high density salt solution
on the recovered fractions and implications for data interpretation. Soil collected from forested sites at H. J. Andrews Experimental
Forest, Oregon and Bousson Experimental Forest, Pennsylvania was separated into light and heavy fractions by floatation in
a 1.6 g cm−3 solution of SPT. Mass balance calculations revealed that between 17% and 26% of the original bulk soil C and N content was
mobilized and subsequently discarded during density fractionation for both soils. In some cases, the light isotope was preferentially
mobilized during density fractionation. During a year-long incubation, mathematically recombined density fractions respired
∼40% less than the bulk soil at both sites and light fraction (LF) did not always decompose more than the heavy fraction (HF).
Residual amounts of tungsten (W) present even in well-rinsed fractions were enough to reduce microbial respiration by 27%
compared to the control in a 90-day incubation of Oa material. However, residual W was nearly eliminated by repeated leaching over the year-long incubation, and is not likely
the primary cause of the difference in respiration between summed fractions and bulk soil. Light fraction at Bousson, a deciduous
site developed on Alfisols, had a radiocarbon-based mean residence time (MRT) of 2.7 or 89 years, depending on the interpretation
of the radiocarbon model, while HF was 317 years. In contrast, both density fractions from H. J. Andrews, a coniferous site
developed on andic soils, had approximately the same MRT (117 years and 93 years for LF and HF). At H. J. Andrews the organic
matter lost during density separation had a short MRT (19 years) and can account for the difference in respired CO2 between the summed fractions and the bulk soil. Recognition and consideration of the effects of the density separation procedure
on the recovered fractions will help prevent misinterpretation and deepen our understanding of the specific role of the recovered
organic matter fractions in the ecological context of the soil studied. 相似文献
89.
S. M. Ghaderian A. Mohtadi R. Rahiminejad R. D. Reeves A. J. M. Baker 《Plant and Soil》2007,293(1-2):91-97
Serpentine soils, which contain relatively high concentrations of nickel and some other metals, are the preferred substrate
for some plants, especially those that accumulate Ni in their tissues. In temperate regions more Ni-hyperaccumulator plants
are found in Alyssum than in any other genus. In this study, serpentine soils of two areas (Marivan and Dizaj) in the west/northwest of Iran and
also perennial Alyssum plants growing on these soils were analyzed for Ni and some other metals. The highest concentrations of total metals in the
soils of these areas for Ni, Cr, Co and Mn were 1,350, 265, 94 and 1,150 μg g−1, respectively, while concentrations of Fe, Mg and Ca reached 3.55%, 16.8% and 0.585% respectively. The concentration of exchangeable
Ni in these soils is up to 4.5 μg g−1. In this study two Alyssum species, A. inflatum and A. longistylum, have been collected from Marivan and Dizaj, respectively. Analysis of leaf dry matter shows that they can contain up to
3,700 and 8,100 μg Ni g−1, respectively. This is the first time that such high Ni concentrations have been found in these species. The concentrations
of other metals determined in these species were in the normal range for serpentine plants, except for Ca, which was higher,
up to 5.3% and 3.5%, respectively 相似文献
90.
R. D. Reeves A. J. M. Baker T. Becquer G. Echevarria Z. J. G. Miranda 《Plant and Soil》2007,293(1-2):107-119
Major collections of the ultramafic flora of Goiás, central Brazil, were made by Brooks and co-workers in 1988 and 1990. At
the time of reports on this material in 1990–1992 much of it had been identified only tentatively and incompletely, but the
area was clearly interesting for taxonomic and biogeochemical reasons. Further progress has been made but still only two-thirds
of the specimens are identified at the species level. Following a third collection in early 2005, we now have 800 specimens
from this area, with chemical analyses of all the plants and of more than 120 representative soil samples. New species have
been found, e.g., in Paspalum (Poaceae) and Pterolepis (Melastomataceae). There is a need for more taxonomic work in genera such as Cnidoscolus (Euphorbiaceae), Lippia (Verbenaceae), Turnera and Piriqueta (Turneraceae), and Vellozia (Velloziaceae). Ni hyperaccumulation (>1,000 mg/kg in dry plant matter) has now been found in a total of 79 specimens, representing
more than 30 different species. Notable Ni hyperaccumulators include Pfaffia sarcophylla (Amaranthaceae), species of Justicia, Lophostachys and Ruellia (Acanthaceae), Porophyllum (Asteraceae), several species of Lippia (Verbenaceae), Turnera and Piriqueta (Turneraceae), and a possibly new Cnidoscolus (Euphorbiaceae). Ni hyperaccumulation has not been found in plants of the outcrops of Morro Feio or Crominia-Mairipotaba;
it seems to be confined to the extensive layered ultramafics of Barro Alto and the Macedo-Niquelandia areas. The distribution
of Ni-values in the Brazilian plant collection is different from that found in the Mediterranean and California, where there
is a clear distinction between accumulator and non-accumulator plants: in Brazil the distribution is more continuous, and
median Ni concentrations are much greater. An ultramafic hill just north of Niquelandia deserves to be protected because of
the presence there of many of the hyperaccumulators and species probably endemic to the Goiás ultramafics. 相似文献