Interspecies variation in DNA damage induced by pollution

The choice of a suitable species to translate pollution signals into a quantitative monitor is a fundamental step in biomonitoring plans. Here we present the results of three years of biomonitoring at a new coal power plant in central Italy using three different aquatic and terrestrial wildlife species in order to compare their reliability as sentinel organisms for genotoxicity. The comet assay was applied to the common land snail Helix spp., the lagoon fish Aphaniusfasciatus, and the green frog Rana esculenta sampled in the area potentially exposed to the impact of the power station. The tissue concentration of some expected pollutants （As, Cd, Ni, Pb, Cr） was analysed in parallel samples collected in the same sampling sites. The three species showed different values in the comet assay （Tail Intensity） and different accumulation profiles of heavy metals. Aphanius fasciatus showed an increasing genotoxic effect over time that paralleled the temporal increase of the heavy metals, especially arsenic, and the highest correlation between heavy metals and DNA damage. Helix spp. showed levels of damage inversely related to the distance from the source of pollution and in partial accordance with the total accumulation of trace elements. On the contrary, Rana esculenta showed a low capability to accumulate metals and had inconsistent results in the comet test. The fish appeared to be the most efficient and sensitive species in detecting chemical pollution. Overall, both the fish and the snail reflected a trend of increasing pollution in the area surrounding the power plant across time and space [Current Zoology 60 （2）： 308-321, 2014].     

Phyto-availability and speciation change of heavy metals in soils amended with lignin as micro-fertilizer

Lignin is a primary byproduct from the black liquor treatment in paper making industries, its application as micro-fertilizer in agricultural land might provide a promising alternative to sewage discharge. However, application of such a micro-fertilizer might affect the soil properties and result in soil pollution. In this study, the effects of lignin application on phyto-availability and speciation change of heavy metals in soils were investigated. Greenhouse experiments showed that lignin application improved the growth of winter wheat (Triticum aestivum L.) in all three soils investigated. The increase of the biomass for wheat shoot was 59.7%, 39.8% and 12.3% for Beijing soil, Jiangxi soil and Dongbei soil, respectively. In contrast, lignin amendment decreased the concentrations of heavy metals in wheat shoots from 2.2% to 61.0%. Sequential extraction procedure of a three-step BCR was used to investigate the fraction distribution. The extractable fractions were specified as fraction B1: water soluble,     

Effect of Pb pollution on the growth,biomass allocation and photosynthesis of Phragmites australis in flood and drought environment北大核心CSCD

Aims Reed (Phragmites australis) is a typical perennial rhizomatic plant with extensive tolerance to environmental stress. In order to better understand the adaptation and tolerance of reeds subjected to heavy metal pollution in different levels of water, we conducted a study on the effects of Pb pollution on growth, biomass and photosynthesis of reeds in flood and drought environment. This research would provide theoretical basis for application of reeds in wetland restoration and remediation. Methods We conducted a pot experiment with destructive sampling after 90 days of growth. The water treatments were main plot, including two water levels. The Pb treatments were secondary plot (nested within water treatments), including five levels (0, 500, 1 500, 3 000, 4 500 mg·kg–1). There were 10 treatments with 12 replicates per treatment. Important findings In the flood environment, Pb pollution significantly inhibited the growth of buds and rhizomes, but had no significant effect on the number of offspring shoots. The offspring shoots had higher growth rate per day, net photosynthetic rate and biomass compared to the parent shoots. In the drought environment, Pb pollution inhibited the growth of roots, buds and rhizomes, and biomass accumulation of parent and offspring shoots as well as photosynthetic parameters. These parameters were lower under the drought condition than in the flood environment. The Pb was mostly concentrated in roots compared to rhizomes and offspring shoots. In both flood and drought environments, the concentration of Pb in parent shoots was about three times of that in offspring shoots. The Pb concentration in offspring shoots under the flood condition was less than that in the drought environment. Overall, these results indicated that the synergistic effect of Pb and drought significantly inhibited the growth, biomass accumulation and photosynthesis of reeds, which might result in reduced offspring productivity and population density and may lead to population decline. However, the flooded reeds could adopt some strategies of Pb allocation to alleviate the negative effect of Pb on the growth, physiology and clonal propagation, benefiting the population reproduction and stabilization. © 2018 Editorial Office of Chinese Journal of Plant Ecology. All rights reserved.     

The development of policy approaches for reducing nitro-gen pollution to coastal waters of the USA

Two-thirds of the coastal rivers and bays in the United States are degraded from nutrient pollution, and nitrogen inputs these waters continue to increase. The nitrogen comes from a variety of sources, including runoff from agricultural fields, concentrated animal feeding operations, atmospheric deposition from fossil fuel combustion, and sewage and septic wastes. Technical solutions for nitrogen pollution exist at reasonable cost. That most of these solutions have not yet been implemented to any significant extent across the United States suggests that new policy approaches are necessary. The best solution may involve a combination of voluntary and mandatory approaches, applying different approaches to different sources of nitrogen pollution. A watershed-based approach that relies heavily on voluntary mechanisms (such as crop-yield insurance to reduce over-fertilization) is likely to be the most effective for some sources of nitrogen (such as runoff from agricultural fields), while a uniform national regulatory approach may be better for others (such as NOx emissions from fossil fuel combustion). Implementation of management strategies should be carefully coupled to monitoring programs to assess the effectiveness of these strategies. While both nitrogen and phosphorus are important to control, the focus should be on nitrogen management, in part because nitrogen is more generally the causal agent of coastal eutrophication. Also, while nitrogen-control practices tend to also reduce phosphorus pollution, phosphorus-control practices often have little effect on nitrogen. Although current scientific and technical knowledge is sufficient to begin to make substantial progress toward solving coastal nitrogen pollution, progress will be made more quickly and more cost effectively with increased investment in appropriate scientific research.     

Rehabilitation of a tailing dam at Shimen County, Hunan Province: Effectiveness assessment

This study was conducted to assess the effectiveness of phytoremediation on a tailing dam located in Shimen County, Hunan Province. Quadrat survey method was employed to investigate and sample the dominant plant species growing on the rehabilitated tailing dam. The fertilities of the soils were assessed, and concentrations of arsenic and other heavy metals in the plant and soil samples were measured. The results showed that no difference was found on the effect of soil capping with top and non-topsoils for rehabilitation of plants on the tailing dam. After rehabilitation, stable vegetation coverage types were established, 39 plant species were found to grow on the tailing dam, and the minimal area for plant communities was 30 m². The dominant plant species were planted Pteris vittata and natural colonizing Miscanthus sinensis. The contents of organic matter, nitrogen and phosphorus in the soils were low, while the potassium content was at a middle level; however, plots where Legumina plants grew were found to have higher level of nitrogen and phosphorus in the growing soils. Arsenic (As) and Cadmium (Cd) concentrations in the soils were 8 and 7 times of the grade III value of the National Standard for Soil Quality (GB15618-1995), respectively; while in tailings these were 81 and 68 times. The available As concentration in the soils ranged as 3.7–29.5 mg kg^?1, whereas the available As concentration in tailings was as high as 61.1 mg kg^?1. Concentrations for most of the heavy metals were in the normal range of terrestrial higher plants, except As and Cd in P. vittata and M. sinensis, and As in the roots of M. sinensis. It is concluded that phytoremediation project has reduced the ecological and health risks caused by the tailing dam to the ambient environment. However, the plants growing on the tailing dam which contained high As and Cd should be kept from entering into food chain in order to protect the health of local residents.     

Rehabilitation of a tailing dam at Shimen County, Hunan Province: Effectiveness assessment

This study was conducted to assess the effectiveness of phytoremediation on a tailing dam located in Shimen County, Hunan Province. Quadrat survey method was employed to investigate and sample the dominant plant species growing on the rehabilitated tailing dam. The fertilities of the soils were assessed, and concentrations of arsenic and other heavy metals in the plant and soil samples were measured. The results showed that no difference was found on the effect of soil capping with top and non-topsoils for rehabilitation of plants on the tailing dam. After rehabilitation, stable vegetation coverage types were established, 39 plant species were found to grow on the tailing dam, and the minimal area for plant communities was 30 m². The dominant plant species were planted Pteris vittata and natural colonizing Miscanthus sinensis. The contents of organic matter, nitrogen and phosphorus in the soils were low, while the potassium content was at a middle level; however, plots where Legumina plants grew were found to have higher level of nitrogen and phosphorus in the growing soils. Arsenic (As) and Cadmium (Cd) concentrations in the soils were 8 and 7 times of the grade III value of the National Standard for Soil Quality (GB15618-1995), respectively; while in tailings these were 81 and 68 times. The available As concentration in the soils ranged as 3.7–29.5 mg kg^?1, whereas the available As concentration in tailings was as high as 61.1 mg kg^?1. Concentrations for most of the heavy metals were in the normal range of terrestrial higher plants, except As and Cd in P. vittata and M. sinensis, and As in the roots of M. sinensis. It is concluded that phytoremediation project has reduced the ecological and health risks caused by the tailing dam to the ambient environment. However, the plants growing on the tailing dam which contained high As and Cd should be kept from entering into food chain in order to protect the health of local residents.     

The nitrogen cycle, scientific uncertainty and policy relevant science

Much of the research on the nitrogen cycle aims to improving scientific understanding but is not focused specifically on removing or reducing the scientific uncertainties that constrain policy makers in the formulation of appropriate responses to old or emerging environmental problems. Policy makers, for example, commonly find it difficult to assess the spatial or temporal importance of the various risks to human and ecosystem health that stem from man's interference with the natural N cycle. This paper will justify this conclusion by reference to the findings of a recent study on non-point pollution from crop production in China. The findings concern the perceived risks of groundwater nitrate to human health; uncertainties about critical NOX levels and their interactions with other pollutants; various other dimensions of man's impact on the N cycle. The paper will go on to suggest a more systematic process or pathway by which scientists can select and design their research in a manner that could give more effective support to policy makers.     

Effects of permafrost degradation on ecosystems

Permafrost, covering approximately 25% of the land area in the Northern Hemisphere, is one of the key components of terrestrial ecosystem in cold regions. As a product of cold climate, permafrost is extremely sensitive to climate change. Climate warming over past decades has caused degradation in permafrost widely and quickly. Permafrost degradation has the potential to significantly change soil moisture content, alter soil nutrients availability and influence on species composition. In lowland ecosystems the loss of ice-rich permafrost has caused the conversion of terrestrial ecosystem to aquatic ecosystem or wetland. In upland ecosystems permafrost thaw has resulted in replacement of hygrophilous community by xeromorphic community or shrub. Permafrost degradation resulting from climate warming may dramatically change the productivity and carbon dynamics of alpine ecosystems. This paper reviewed the effects of permafrost degradation on ecosystem structure and function. At the same time, we put forward critical questions about the effects of permafrost degradation on ecosystems on Qinghai–Tibetan Plateau, included: (1) carry out research about the effects of permafrost degradation on grassland ecosystem and the response of alpine ecosystem to global change; (2) construct long-term and located field observations and research system, based on which predict ecosystem dynamic in permafrost degradation; (3) pay extensive attention to the dynamic of greenhouse gas in permafrost region on Qinghai–Tibetan Plateau and the feedback of greenhouse gas to climate change; (4) quantitative study on the change of water-heat transport in permafrost degradation and the effects of soil moisture and heat change on vegetation growth.     

Plant biotic interactions

<正>Plants are constantly under attack by pathogens,pests,and parasites,resulting in severe consequences on global food production and human health.While pathogens and pests find their ways to invade and communicate with their hosts,plants have evolved sophisticated immune systems to fight infections.In the field of plant-microbial interactions,most of the studies have focused on the function and signaling rial     

Effects of permafrost degradation on ecosystems

Permafrost, covering approximately 25% of the land area in the Northern Hemisphere, is one of the key components of terrestrial ecosystem in cold regions. As a product of cold climate, permafrost is extremely sensitive to climate change. Climate warming over past decades has caused degradation in permafrost widely and quickly. Permafrost degradation has the potential to significantly change soil moisture content, alter soil nutrients availability and influence on species composition. In lowland ecosystems the loss of ice-rich permafrost has caused the conversion of terrestrial ecosystem to aquatic ecosystem or wetland. In upland ecosystems permafrost thaw has resulted in replacement of hygrophilous community by xeromorphic community or shrub. Permafrost degradation resulting from climate warming may dramatically change the productivity and carbon dynamics of alpine ecosystems. This paper reviewed the effects of permafrost degradation on ecosystem structure and function. At the same time, we put forward critical questions about the effects of permafrost degradation on ecosystems on Qinghai–Tibetan Plateau, included: (1) carry out research about the effects of permafrost degradation on grassland ecosystem and the response of alpine ecosystem to global change; (2) construct long-term and located field observations and research system, based on which predict ecosystem dynamic in permafrost degradation; (3) pay extensive attention to the dynamic of greenhouse gas in permafrost region on Qinghai–Tibetan Plateau and the feedback of greenhouse gas to climate change; (4) quantitative study on the change of water-heat transport in permafrost degradation and the effects of soil moisture and heat change on vegetation growth.     

Cadmium resistance in transgenic tobacco plants enhanced by expressing bean heavy metal-responsive gene <Emphasis Type="Italic">PvSR2</Emphasis>

PvSR2 (Phaseolus vulgaris stress-related gene) has been cloned from French bean and shown to be expressed specifically upon heavy metal treatment. In order to investigate the role of PvSR2 in plant, PvSR2 gene under the control of cauliflower mosaic virus 35S promoter was introduced into tobacco mediated with Agrobacterium tumefaciens LBA4404. The regenerated plantlets were selected on medium with 100 mg/L kanamycin. PCR and Southern blot analysis showed PvSR2 gene was integrated in tobacco genome. Gus and Northern blot analysis indicated PvSR2 gene was expressed in transgenic seedling. The heavy metal resistance assay showed that the transgenic tobacco seedlings with the PvSR2 coding sequence exhibited higher tolerance to Cd compared with wild-type (WT) under Cd exposure. The Cd content accumulated in root between transgenic and WT seedlings had no obvious difference at lower Cd external concentration (0.05-0.075 mmol/L CdCl2), whereas transgenic plant showed a lower root Cd content than the control at higher external Cd concentration (0.1 mmol/L CdCl2). These results suggested that the expression of PvSR2 can enhance the Cd tolerance, and PvSR2 may be involved in Cd transportation and accumulation at the test concentration of 0.1 mmol/L Cd.     

小鼠金属硫蛋白突变体αα-cDNA在烟草中的表达及转基因烟草对Cd~(2+)抗性的提高

金属硫蛋白是一类小分子量的金属结合蛋白 ,有 β,α两个结构域 .用另一个 α结构域取代金属硫蛋白的 β结构域 ,得到突变体 αα.通过 PCR法在 αα- c DNA翻译起始密码子 ATG前加入植物偏爱的碱基组合 AACA,构建 Ca MV双 35S启动子驱动的 αα- c DNA植物表达载体 p GPTVd35S-αα,此载体以抗除草剂基因 ( bar)作为选择标记物 .用根癌农杆菌介导的叶盘法对栽培种烟草 NC89进行转化 .Southern和 Western印迹分析表明突变体αα- c DNA已整合进入烟草基因组并且可以正常表达 .Northern印迹结果显示突变体αα- c DNA在烟草根部的表达强于叶部 .烟草根、茎、叶Cd2 +含量分析表明 ,转基因植物与对照相比 ,Cd2 +更多地集中在根部 ,在一定程度上降低了叶片中的 Cd2 + 含量 .Cd2 + 抗性实验进一步证明突变体αα- c DNA的表达提高了转基因烟草对 Cd2 + 的抗性 :转基因烟草在 2 0 0μmol/L Cd Cl2 条件下生长正常 ,在 40 0μmol/Cd Cl2 培养基内也可以存活 .而 1 0 0μmol/L Cd Cl2 即成为对照烟草的致死剂量 .     

Phytochelatin synthase of Thlaspi caerulescens enhanced tolerance and accumulation of heavy metals when expressed in yeast and tobacco

Phytochelatin synthase (PCS) is key enzyme for heavy metal detoxification and accumulation in plant. In this study, we isolated the PCS gene TcPCS1 from the hyperaccumulator Thlaspi caerulescens. Overexpression of TcPCS1 enhanced PC production in tobacco. Cd accumulation in the roots and shoots of TcPCS1 transgenic seedlings was increased compared to the wild type (WT), while Cd translocation from roots to shoots was not affected under Cd treatment. The root length of the TcPCS1 transgenic tobacco seedlings was significantly longer than that of the WT under Cd stress. These data indicate that TcPCS1 expression might increase Cd accumulation and tolerance in transgenic tobacco. In addition, the malondialdehyde content in TcPCS1 plants was below that of the wild type. However, the antioxidant enzyme activities of superoxide dismutase, peroxidase and catalase were found to be significantly higher than those of the WT when the transgenic plant was exposed to Cd stress. This suggests that the increase in PC production might enhance the Cd accumulation and thus increase the oxidative stress induced by the cadmium. The production of PCs could cause a transient decrease in the cytosolic glutathione (GSH) pool, and Cd and lower GSH concentration caused an increase in the oxidative response. We also determined TcPCS1 in Thlaspi caerulescens was regulated after exposure to various concentrations of CdCl₂ over different treatment times. Expression of TcPCS1 leading to increased Cd accumulation and enhanced metal tolerance, but the Cd contents were restrained by adding zinc in Saccharomyces cerevisiae transformants.     

Cadmium tolerance and accumulation in Indian mustard is enhanced by overexpressing gamma-glutamylcysteine synthetase

To investigate rate-limiting factors for glutathione and phytochelatin (PC) production and the importance of these compounds for heavy metal tolerance, Indian mustard (Brassica juncea) was genetically engineered to overexpress the Escherichia coli gshI gene encoding gamma-glutamylcysteine synthetase (gamma-ECS), targeted to the plastids. The gamma-ECS transgenic seedlings showed increased tolerance to Cd and had higher concentrations of PCs, gamma-GluCys, glutathione, and total non-protein thiols compared with wild-type (WT) seedlings. When tested in a hydroponic system, gamma-ECS mature plants accumulated more Cd than WT plants: shoot Cd concentrations were 40% to 90% higher. In spite of their higher tissue Cd concentration, the gamma-ECS plants grew better in the presence of Cd than WT. We conclude that overexpression of gamma-ECS increases biosynthesis of glutathione and PCs, which in turn enhances Cd tolerance and accumulation. Thus, overexpression of gamma-ECS appears to be a promising strategy for the production of plants with superior heavy metal phytoremediation capacity.     

Inheritance and expression of the mouse metallothionein gene in tobacco: impact on cd tolerance and tissue cd distribution in seedlings

Genetically engineered seedlings obtained from self-fertilized transgenic tobacco (Nicotiana tabacum) contained and expressed the mouse metallothionein and kanamycin resistance marker genes and were more tolerant to cadmium stress than untransformed controls. Cadmium accumulation in leaves of transgenic seedlings exposed to a low, field-like Cd concentration (0.02 micromolar) was about 20% lower than that in untransformed controls. Genetic analysis of R1 and R2 progeny showed inheritance of the marker gene to be as a dominant Mendelian trait. These results suggest the possibility of developing transgenic plants with modified tolerance to heavy metal stress and food crops having lower Cd content.     

Functional analyses of TaHMA2, a P1B‐type ATPase in wheat

Currently, there are few studies concerning the function of heavy metal ATPase 2 (HMA2), particularly in monocotyledons, and the potential application of this protein in biofortification and phytoremediation. Thus, we isolated and characterized the TaHMA2 gene from wheat (Triticum aestivum L.). Our results indicate that TaHMA2 is localized to the plasma membrane and stably expressed, except in the nodes, which showed relatively high expression. Zinc/cadmium (Zn/Cd) resistance was observed in TaHMA2‐transformed yeast. The over‐expression of TaHMA2 increased the elongation and decreased the seed‐setting rate in rice (Oryza sativa L.), but not Arabidopsis thaliana, tobacco (Nicotiana tabacum L.) or wheat. TaHMA2 over‐expression also improved root‐shoot Zn/Cd translocation, especially in rice. The seeds of transgenic rice and wheat, not tobacco, showed decreased Zn concentrations. The Zn concentration was decreased in all parts of the transgenic rice seeds, but was decreased only in the ventral endosperm of wheat, which showed an increased Zn concentration in the embryo and aleurone. The over‐expression of TaHMA2 improved plant tolerance under moderate Zn stress and Zn deficiency, but Zn and Cd resistance decreased under high levels of Zn and Cd stress, respectively. The Cd concentration in transgenic rice seedlings was dramatically increased under Zn deficiency. Thus, over‐expression of TaHMA2 showed a more obvious phenotype in monocotyledons than in dicotyledons. These findings provide important information for TaHMA2, and more efforts should be made in the future to characterize the reduced Zn concentration in TaHMA2 transgenic grains and the diversity of TaHMA2 substrate specificity.     

Transgenic Tobacco with αα Mutant Gene Has Higher Tolerance to Heavy Metals

Metallothionein (MT) has two domains, α and β domain. α domain preferred to bind Cd2+and Hg2+. Mouse metallothionein mutant αα has been constructed and expressed in E.coli, which has the same stability as the nature one but has stronger affinity to heavy metals. To testify the result in vivo, αα mutant gene was cloned into plant expression vector pE3 under the CaMV 35S promoter. A transgenic tobacco was obtained by using leaf discs of tobacco (Nicotiana tabacum L. cv. NC89) to Agrobacterium-mediated ααgene transfer. Southern blotting analysis indicated that the αα mutant gene was indeed integrated into the tobacco genome; Western blot indicated that the αα mutant gene was expressed in transgenic tobacco. It was also demonstrated that the transgenic tobacco with αα mutant gene have a little higher tolerance to heavy metals than that with natural MT gene. Moreover, the transgenic tobacco can accumulate more Cd2+ in its roots than natural, so that, it can decrease the concentration of Cd2+ in its leaves.     

转彩色马铃薯StAN1基因的烟草幼苗耐旱性分析

该研究以转彩色马铃薯StAN1基因烟草为材料、野生型烟草(WT)为对照,测定分析转StAN1基因烟草在种子萌发期、幼苗期和苗期对干旱(甘露醇)处理的耐受情况,并对苗期旱热共同胁迫的耐受情况进行测定分析,以探讨彩色马铃薯StAN1基因的功能,为耐旱彩色马铃薯育种提供新路径。结果显示:(1)转StAN1基因烟草鉴定显示,阳性率为82.6%,且转基因烟草的叶片明显变紫,花青素含量极显著高于野生型烟草。(2)在培养基甘露醇浓度为150 mmol/L时,点播在培养基上的转基因烟草种子第5天时的萌发率达到了7%,是野生型烟草萌发率的2.3倍。(3)在甘露醇浓度为0和100 mmol/L的培养基上竖直培养时,转基因烟草的根长分别是野生型烟草的1.46和1.30倍,根长比野生型烟草显著增长。(4)在干旱胁迫下,转基因烟草幼苗叶片中的脯氨酸含量以及超氧化物歧化酶活性均显著高于野生型烟草,丙二醛含量均显著低于野生型烟草。(5)转基因烟草LEA基因和ERF基因在干旱和旱热处理中的相对表达量均高于野生型烟草。研究表明,StAN1基因在提高植物花青素含量的同时也提高了植物的耐旱性。