Centaurin-like protein Cnt5 contributes to arsenic and cadmium resistance in fission yeast

Arsenic (As) and cadmium (Cd) are two of the most hazardous substances in the environment and have been implicated in a number of human diseases including cancer. Their mechanisms of toxicity and subsequent carcinogenesis are not understood. To identify the genes involved in As/Cd detoxification, we screened a random insertional mutagenesis library of Schizosaccharomyces pombe for mutants that are hypersensitive to As/Cd. Mutations were mapped to spc1 ⁺ ( sty1 ⁺) and SPBC17G9.08c . Spc1 is a stress-activated protein kinase orthologous to human p38. A fragment of SPBC17G9.08c was previously identified as csx2 , a high-copy suppressor of cut6 that encodes an acetyl-CoA carboxylase involved in fatty acid biosynthesis. SPBC17G9.08c is a member of the centaurin ADP ribosylation factor GTPase activating protein family found in a variety of fungi, plants and metazoans, but not in Saccharomyces cerevisiae . Cnt5, so named because its closest human homolog is centaurin β-5, binds to phosphatidic acid and phosphatidyl serine in vitro . Microscopic localization of Cnt5-GFP indicates significant redistribution of Cnt5 from the cytoplasm to the cell membranes in response to As stress. These data suggest a model in which Cnt5 contributes to As/Cd resistance by maintaining membrane integrity or by modulating membrane trafficking.     

Oxidative stress induced by lead, cadmium and arsenic mixtures: 30-day, 90-day, and 180-day drinking water studies in rats: An overview

Humans are frequently exposed to combinations of lead (Pb), cadmium (Cd) and Arsenic (As) but there is a paucity of actual data on the molecular effects of these agents at low dose levels. The present factorial design studies were undertaken in rats to examine the effects of these agents at LOEL dose levels on a number of molecular parameters of oxidative stress in hematopoietic and renal organ systems following oral exposure in drinking water at 30, 90 and 180 day time points. Results of these studies demonstrated dynamic, time-dependent alterations in both molecular targets and inducible oxidative stress protective systems in target cell populations. In general, cellular protective systems, which protected against oxidative damage at the 90 day time point, appeared to be finite such that molecular manifestations of oxidative stress became statistically significant at the 180 day time point for several of the combination exposure groups. These data demonstrate the importance of duration of exposure in assessing the toxic potential of Pb, Cd and As mixtures at low dose levels.     

Risk assessment on renal dysfunction caused by co-exposure to arsenic and cadmium using benchmark dose calculation in a Chinese population

Arsenic and cadmium are important inorganic toxicants in the environment. Humans certainly have the potential to be exposed to the mixtures of arsenic and cadmium, but the toxicological interactions of these inorganic mixtures are poorly defined. A general population co-exposed to arsenic and cadmium, was selected in China. The total number of participants was 245, made up of 122 in the arsenic-cadmium polluted area, 123 in the non polluted area. Urinary arsenic (UAs) and cadmium (UCd) were determined by atomic absorption spectrometry as exposure biomarkers and beta2-microglobulin (Ubeta2MG), albumin (UALB), N-acetyl-beta2-glucosaminidase (UNAG) in urine were determined as effect biomarkers. The benchmark dose (BMD) and the lower confidence limit on the benchmark dose (LBMD) were calculated to estimate the critical concentration of UAs and UCd. UAs and UCd concentrations in the polluted area were significantly higher than those in the non polluted area (P < 0.01). The levels of Ubeta2MG, UALB and UNAG in the polluted area were significantly higher than those in the non polluted area (P < 0.01). The BMD/LBMD of UAs and UCd for a 10% level of risk above the background level were estimated as 121.91/102.11 microg/g creatinine and 1.05/0.88 microg/g creatinine. It was suggested that the lower confidence limit of population critical concentration of UAs and UCd for renal dysfunction for 10% excess risk level above the background, which is obtained from LBMD, may need to be kept below 102 and 0.88 microg/g creatinine in order to prevent renal damage in general population co-exposed to arsenic and cadmium. It is indicated that combined effect of arsenic and cadmium were additive effect and/or synergistic effect, and cadmium may potentiate arsenic nephrotoxicity during the long-term and co-exposure to arsenic and cadmium in humans.     

心脏基因转录潜能的区域化

心脏基因在心肌中的区域化表达是一个非常普遍的现象,通过转基因动物研究心肌中的转录潜能的区域化已取得了重大的进展.房室转录区域化最早是在线状心管形成时开始出现的.之后,在胚胎心脏的各个部分均可以发现转基因区域化表达.对于转基因在心肌中区域化表达的分子机理的研究,现在主要集中在对转基因调控区域的顺式调控元件和反式调控元件的解析,以及在心肌细胞中对于转录很重要的基因或是已被证明会介导位置信息的基因的表达模式和功能的研究上.     

区域PRED模型在环境区划中的应用

通过分析区域ＰＲＥＤ模型的特点和结构,显示了该模型在环境区划中的广泛应用前景和重要意义．该模型既丰富了环境区划的理论基础,又使区划的指标体系增加了新的内容,使研究者能更多地着眼于系统的协调发展．     

镉吸附细菌的分离及其对土壤镉的固定

[目的] 探究镉吸附细菌是否能够高效固定土壤有效镉（Cd）,为土壤有效Cd的微生物固定提供理论依据。[方法] 利用含Cd²⁺牛肉膏蛋白胨液体培养基对细菌进行Cd的耐受性测试筛选出镉抗性强的菌株;通过16S rRNA基因相似性及系统进化分析鉴定耐镉细菌,将菌细胞加入含CdCl₂溶液中进行Cd²⁺吸附效率测定;通过土培模拟实验,测定土壤pH、碱解氮、有效磷、速效钾、有机质、CEC、有效Cd及微生物数量来分析镉吸附细菌对镉污染土壤的影响。[结果] 从德阳鱼腥草根际土壤中分离获得的57株细菌对Cd²⁺表现出不同程度的抗性,并从中筛选出3株耐Cd优势细菌普罗威登斯菌属（Providencia）DY8、芽孢杆菌属（Bacillus）DY3和芽孢杆菌属（Bacillus）DY1-4。其对溶液中的Cd²⁺表现出较好的吸附作用,吸附效率随着Cd²⁺浓度升高而降低。DY8、DY3、DY1-4能使镉污染土壤中有效Cd含量分别降低72.11%、68.55%、62.32%,同时显著提高镉污染土壤中碱解氮、有效磷的含量。[结论] Cd污染农田土壤中含有丰富的耐Cd微生物资源,Cd吸附细菌能降低土壤中有效Cd的含量,且能有效改善土壤养分条件。     

Uptake of soil cadmium by three field crops and its prediction by a pH-dependent Freundlich sorption model

Crop contamination with cadmium is a function of soil contamination. Here we study the applicability of the soil solution bioavailability hypothesis to Cd: that is, whether uptake of Cd was more directly related to its concentration or activity in the soil solution than in the soil solid phase. Experimental data from past soil-crop surveys for Cd were used to test this hypothesis. It was also investigated whether pH-dependent desorption of cadmium would be an important mechanisms in affecting cadmium activity and thus uptake. To do so we calculated the correlation between the Cd transfer factor (ratio between Cd level in plant dry material and Cd level in the topsoil) and either the soil pH, or the calculated soil solution Cd concentrations. There was no correlation between the Cd contents of the soil and of the edible parts of leafy plants (endive, spinach and lettuce). There was a strong negative correlation between soil pH and the log transfer factor for Cd at pH 4.5–7.2 and thus plant content. There also was a negative correlation between soil pH and calculated cadmium concentrations in the soil solution. For spinach grown on soils with pH > 7.2 the transfer factor increased, which is tentatively ascribed to cadmium mobilization by dissolved organic matter. The soil solution hypothesis should be further tested by pot and field trials. Special attention should be paid to the role of pH and dissolved organic matter. A C Borstlap Section editor     

Absorption of cadmium after a long-term oral administration of cadmium to dogs

A long-term experiment using beagle dogs to investigate the absorption of cadmium was conducted. The dogs in the experimental groups were given a commercial diet and pelleted food containing 1, 3, 10, 50, and 100 mg of cadmium per day. The cadmium concentration in the blood increased continuously, gradually reaching a steady state following the administration of cadmium. The cadmium excreted daily in urine increased continuously. The cumulative excreted amount of cadmium in urine was calculated by using the trapezoidal rule based on the data of excretion of cadmium in urine. Then the absorbed fraction of administered cadmium was estimated on the basis of the relationship between the cumulative excreted amount of cadmium in urine and the cumulative administered dose of cadmium after the cadmium concentration in blood reached a steady state. The absorbed fraction of cadmium decreased with an increase in the administered dose of cadmium. A dose-dependent increase between the absorbed amount and the administered dose was observed.     

An Ecogeographical Regionalization for Biodiversity in China

Ecogeographical regionalization is the basis for spatial differentiation of biodiversity research. In view of the principle of international ecogeographical regionalization, this study has applied multivariate analysis and GIS method and based on some ecogeographical attributes limited to the distribution of plant and vegetation, including climatic factors, such as minimum temperature, mean temperature of the coldest month, mean temperature of the wannest month, annual average temperature, precipitation of the coldest month, precipitation of the wannest month, annual precipitation, CV of annual precipitation, biological factors such as vegetation types, vegetation division types, NPP, fiorisitic types, fauna types, abundance of plant species, genus and endemic genus; soil factors such as soil types, soil pH;topographical factors as longitude, latitude and altitude etc. The ecogeographical regionalization for biodiversity in China was made synthetically by using fuzzy cluster method. Four classes of division were used, viz., biodomain, subbiodomain, biome and bioregion. Five biodomains, seven subbiodomains and eighteen biomes were divided in China as follows: Ⅰ Boreal forest biodomain. Ⅰ A Eurasian boreal forest subbiodomain. Ⅰ A1 Southern Taiga mountain cold-temperate coniferous forest biome; Ⅰ A2 North Asian mixed coniferous-broad-leaved forest biome. Ⅱ Northern steppe and desert biodomain. Ⅱ B Eurasian steppe subbiodomain. Ⅱ BI Inner Asian temperate grass steppe biome; Ⅱ B2 Loess Plateau warm-temperate forest/shmb steppe biome. Ⅱ C Asia-Mrica desert subbiodomain. Ⅱ C1 Mid-Asian temperate desert biome; Ⅱ C2 Mongolian/Inner Asian temperate desert biome. Ⅲ East Asian biodomain. Ⅲ D East Asian deciduous broad-leaved forest subbiodomain. Ⅲ D1 East Asian deciduous broad-leaved forest biome, Ⅲ E East Asian evergreen broad-leaved forest subbiodomain. Ⅲ El East Asian mixed deciduous-evergreen broad-leaved forest biome; Ⅲ E2 East Asian evergreen broad-leaved forest biome; Ⅲ E3 East Asian monsoon evergreen broad-leaved forest biome; Ⅲ FA Western East Asian mountain evergreen broadleaved forest biome. Ⅳ Palaeotropical subdomain. IV F India-Malaysian tropical forest subbiodomain.Ⅳ Fl Northern tropical rain forest/seasonal rain forest biome; Ⅳ F2 Tropical island coral reef vegetation biome. Ⅴ Asian plateau biodomain. Ⅴ G Tibet Plateau subbiodomain. Ⅴ G1 Tibet alpine highcold shrub meadow biome;Ⅴ G2 Tibet alpine high-cold steppe biome; Ⅴ G3 Tibet alpine high-cold desert biome; Ⅴ G4 Tibet alpine temperate steppe biome; Ⅴ G5 Tibet alpine temperate desert biome.     

Systematic engineering of phytochelatin synthesis and arsenic transport for enhanced arsenic accumulation in E. coli

Phytochelatin (PC) is a naturally occurring peptide with high affinity towards arsenic (As). In this article, we demonstrated the systematic engineering of PC‐producing E. coli for As accumulation by addressing different bottlenecks in PC synthesis as well as As transport. Phytochelatin synthase from Schizosaccharomyces pombe (SpPCS) was expressed in E. coli resulting in 18 times higher As accumulation. PC production was further increased by co‐expressing a feedback desensitized γ‐glutamylcysteine synthetase (GshI*), resulting in 30‐fold higher PC levels and additional 2‐fold higher As accumulation. The significantly increased PC levels were exploited further by co‐expressing an arsenic transporter GlpF, leading to an additional 1.5‐fold higher As accumulation. These engineering steps were finally combined in an arsenic efflux deletion E. coli strain to achieve an arsenic accumulation level of 16.8 µmol/g DCW, a 80‐fold improvement when compared to a control strain not producing phytochelatins. Biotechnol. Bioeng. 2010. 105: 780–785. © 2009 Wiley Periodicals, Inc.     

中国生态环境区划初探

中国生态环境区划初探高密来（中国人民大学区域经济研究所北京１００８７２）ＡｎＡｐｐｒｏａｃｈｔｏｔｈｅＲｅｇｉｏｎａｌｉｚａｔｉｏｎｏｆＥｃｏｌｏｇｉｃａｌＥｎｖｉｒｏｎｍｅｎｔｉｎＣｈｉｎａ．￥ＧａｏＭｉｌａｉ（ＩｎｓｔｉｔｕｔｅｏｆＲｅｇｉｏｎａ...     

重庆市生态功能区的划分

生态功能又称生态服务功能,是指生态系统与生态过程所形成及所维持的人类赖以生存的自然环境条件与效用.生态功能区划是研究生态系统生态功能,判断生态系统分异和变化特征,提出生态退化恢复策略的基础.重庆市生态功能区划采用3级分区（自然生态区、生态亚区和生态功能区）的等级体系,采用定性与定量相结合的方法进行区划.其中,自然生态区的划分以自然环境因素中的地貌因子为主要指标,采用聚类分析法与图形叠置法来进行;生态亚区的划分采用选取形成生态系统特征、影响生态服务功能的特征因子进行聚类分析,并辅之以主成分分析法来完成;生态功能区的划分以生态敏感性评价和生态服务功能重要性的评价结果为依据,采用主导标志法进行区域划分.区划界线的拟订采用专家智能集成、数理统计分析与GIS的空间表达相结合的方法.最后将重庆市生态功能区划分为4个自然生态区,7个生态亚区,13个生态功能区.     

秦岭种子植物区系分区研究

在吴征镒1983年中国植物区系分区的基础上,依据秦岭山地的自然环境特点,并结合植被优势种及区系特有种和特征种的分布情况,按照发生学原则,将秦岭种子植物区系划分为两大植物地区,五个植物亚地区,七个植物省,并对每个植物省区系的特点进行了分析,结果进一步证明秦岭是我国植物区系南北分异的一条主要界限。     

Epidemiological associations between arsenic and cancer in Argentina

The population of a large central area of Argentina is affected by a syndrome designed as “regional and endemic chronic hydroarsenicism.” A number of types of neoplasms, especially of skin, urinary bladder, and of digestive system, occur with higher frequency in these areas. Drinking water in some of the affected areas contains from 0.1 to 1.2 mg/L of As.     

东北植被区划及其分布格局

根据多因子环境要素聚类结果, 结合地貌分异、气候区划和土壤区划, 对东北植被进行了重新区划, 并论述了海拔高度决定的东北植被的垂直分布规律。松嫩平原、辽河平原构成的松辽平原的植被主体为草甸, 针茅(Stipa)等群落分布于较高地势的二级台地或沙丘上, 为草甸植被中不连续分布的沙地植被类型或海拔决定的垂直植被带的草原类型。据此, 将松辽平原植被区划为温带落叶阔叶林区域, 即将温带草原区南部的东侧界限划定在大兴安岭山脊线附近, 北部寒温带针林南部界限和南部暖温带落叶林北部界线遵从现有研究结果。东北植被分布具有明显的受海拔决定的垂直地带性上的环状分布格局 特点。     

Two models for screening chelating agents for cadmium removal

The effectiveness of some chelating agents to mobilize cadmium from Chinese hamster ovary cells after chronic exposure (20 hr), as well as from cytosolic metallothionein, was studied. In the first protocol, the most effective substance was 2,3-dimercaptopropanol, followed by 2,3-dimercaptopropane-1-sulfonate and 2,3-dimercaptosuccinic acid, whereas CaNa₃3-diethylenetriamine pentaacetic acid × 5H₂O showed less effect. Simultaneous incubation of cells with cadmium and the chelating agent resulted in a different order of effectiveness: CaNa₃ DTPA prevented cadmium uptake almost totally, 2,3-mercaptopropanol by 75% and 2,3-dimercaptopropane-1-sulfonate by 35%. Neither CaNa₃-diethylenetriamine pentaacetic acid × 5H₂O nor 2,3-dimercaptosuccinic acid had altered the distribution of cadmium between the cytosolic protein fractions after a 2 hr incubation of cells, whereas after this period, 2,3-dimercaptopropanol had removed all cadmium from metallothionein, and 2,3-dimercaptopropane-1-sulfonate about 50%. None of the chelating agents had reduced the amount of Cd bound to high molecular weight proteins. In the cell free system, 2,3-dimercaptopropanol and 2,3-dimercaptopropane-1-sulfonate were equally effective and removed all cadmium from metallothionein within ten minutes. CaNa₃-diethylenetriamine pentaacetic acid × 5H₂O, however, even after 60 min, had removed only 50% of the cadmium. The remaining cadmium was found distributed to the high molecular weight and lower molecular weight protein fractions.Abbreviations BAL 2,3-dimercaptopropanol - CHO Chinese hamster ovary cells - DMPS 2,3-dimercaptopropane-1-sulfonate - DMSA 2,3-dimercaptosuccinic acid - DTPA CaNa₃-diethylenetriaminepentaacetic acid × 5 H₂O - HMW proteins high molecular weight proteins - MT metallothionein     

Use of the industrial yeastCandida utilis for cadmium sorption

The sorption ability of Candida utilis biomass for cadmium ions with accumulating competence of dried cells and cells in alginate was compared. After an optimization of process conditions (pH 5.5, biomass concentration 1 g/L and c0 50 mg/L), the cadmium sorption capacity of dried yeast biomass was perceptibly higher than that of the other tested adsorbents. Considering the sorption of the dried yeast biomass equal to 100 %, the cells in alginate reached 86 % while native cells showed only 42 %.     

The influence of chemical form and concentration of arsenic on rice growth and tissue arsenic concentration

Arsenic absorption by rice (Oryza sativa, L.) in relation to the chemical form and concentration of arsenic added in nutrient solution was examined. A 4 × 3 × 2 factorial experiment was conducted with treatments consisting of four arsenic chemical forms [arsenite, As(III); arsenate, As(V); monomethyl arsenic acid, MMAA; and dimethyl arsenic acid, DMAA], three arsenic concentrations [0.05, 0.2, and 0.8 mg As L^-1], and two cultivars [Lemont and Mercury] with a different degree of susceptibility to straighthead, a physiological disease attributed to arsenic toxicity. Two controls, one for each cultivar, were also included. Arsenic phytoavailability and phytotoxicity are determined primarily by the arsenic chemical form present. Application of DMAA increased total dry matter production. While application of As(V) did not affect plant growth, both As(III) and MMAA were phytotoxic to rice. Availability of arsenic to rice followed the trend: DMAA<As(V)<MMAA<As(III). Upon absorption, DMAA was readily translocated to the shoot. Arsenic(III), As(V), and MMAA accumulated in the roots. With increased arsenic application rates the arsenic shoot/root concentration decreased for the As(III) and As(V) treatments. Monomethyl arsenic acid (MMAA), however, was translocated to the shoot upon increased application. The observed differential absorption and translocation of arsenic chemical forms by rice is possibly responsible for the straighthead disorder attributed to arsenic.