植物对重金属的吸收和分布

植物修复是利用植物来清除污染土壤中重金属的一项技术。该技术成功与否取决于植物从土壤中吸取金属以及向地上部运输金属的能力。植物对金属的吸收主要取决于自由态离子活度。许多螯合剂能诱导植物对重金属的吸收。金属离子在液泡中的区域化分布是植物耐重金属的主要原因。同时,细胞内的金属硫蛋白、植物螯合脓等蛋白质以及有机酸、氨基酸等在金属贮存和解毒方面也起重要作用。本文还论述了重金属在植物体内运输的生理及分子方面的研究进展。     

Influence of the arbuscular mycorrhizal fungus Glomus mosseae on uptake of arsenate by the As hyperaccumulator fern Pteris vittata L.

We report for the first time some effects of colonization by an arbuscular mycorrhizal (AM) fungus (Glomus mosseae) on the biomass and arsenate uptake of an As hyperaccumulator, Pteris vittata. Two arsenic levels (0 and 300 mg As kg^–1) were applied to an already contaminated soil in pots with two compartments for plant and hyphal growth in a glasshouse experiment. Arsenic application had little or no effect on mycorrhizal colonization, which was about 50% of root length. Mycorrhizal colonization increased frond dry matter yield, lowered the root/frond weight ratio, and decreased frond As concentration by 33–38%. Nevertheless, transfer of As to fronds showed a 43% increase with mycorrhizal colonization at the higher soil As level. Frond As concentrations reached about 1.6 g kg^–1 (dry matter basis) in non-mycorrhizal plants in the As-amended soil. Mycorrhizal colonization elevated root P concentration at both soil As levels and mycorrhizal plants had higher P/As ratios in both fronds and roots than did non-mycorrhizal controls.     

Enhancing Drought Tolerance in Wheat through Improving MorphoPhysiological and Antioxidants Activities of Plants by the Supplementation of Foliar Silicon

The main objective of the research is to assess the role of foliar application of silicon (Si) for enhancing the survival ability of wheat under drought stress through improving its morphology, physicochemical and antioxidants activities. Treatments were five doses of Si at the rate of 2, 4, 6 and 8 mM and a control. After completion of seeds germination, pots were divided into four distinct groups at various field capacity (FC) levels, such as 100% FC (well-irrigated condition), 75% FC (slight water deficit), 50% FC (modest water deficit) and 25% FC (severe water deficit stress condition). Foliar application of Si at the rate of 2, 4, 6 and 8 mM and a control were given after 30 days of sowing at the tillering stage of wheat. Findings of the present investigation indicated that increasing the level of water deficit stress reduced the morphological parameters (such as root and shoot fresh and dry-biomass weight) and physico-biochemical events ((such as chlorophyll contents by estimating SPAD value), total free amino acid (TFAA), total soluble sugar (TSS), total soluble protein (TSP), total proline (TP), CAT (catalase), POD (peroxidase), SOD (superoxide dismutase) and APX (ascorbate peroxidase)) of wheat; while foliar application of Si at 6 mM at tillering stage enhanced the drought tolerance in wheat by increasing morphology and physiochemical characters under all levels of drought stress. Similarly, antioxidants activities in wheat also enhanced by the application of Si at 6 mM under normal as well as all drought stress levels. Therefore, it may be concluded that foliar application of Si at 6 mM at the tillering stage of wheat is an important indication for increasing the drought tolerance by improving the morphology, physico-biochemical and antioxidants activities in plants under deficit water (drought) conditions.     

珠三角地区几种耐荫耐旱乡土地被植物的园林应用

通过在珠三角地区的广州白云山、肇庆鼎湖山、深圳梧桐山、惠州南昆山、东莞银屏山、东莞水濂山等6处选取样方进行实地调查,并采用线性加权综合法数学模型对珠三角地区野生地被植物作综合评价。结果表明,依据植物的生活型、生境、高度等特性初步确定该地区乡土地被植物70种,重点推荐紫金牛Ardisia japonica、东方紫金牛Ardisia squamulosa、马蓝Strobilanthes cusia等8种乡土耐荫耐旱地被,其在东莞植物园的配置应用实践中,均表现出极好的耐荫性和耐旱性,且扩繁较易。     

镉和砷在植物中的积累及其分子调控机制研究进展

植物源食物是人类摄入有毒金属元素镉(Cd)和砷(As)的主要途径。深化植物对Cd和As积累途径分子机制的认识,有助于培育可食部分中低有毒金属元素含量的作物新种质。该文基于近年来有关植物Cd和As积累在主要模式植物中所取得的实质性研究进展,对植物介导Cd和As吸收的转运蛋白、As形态和生物转化机制以及控制Cd和As根-地上部转运效率和分配的关键因子等方面的研究进展进行综述,并对未来的研究前景进行了展望。     

Toxicity and bioremediation of As(III) and As(V) in the green microalgae Botryococcus braunii: A laboratory study

Worldwide threats of fuel shortages in the near future and climate change because of greenhouse gas emissions are posing severe challenges and therefore it is vital to search for sustainable ways of preventing the consequences. The dual use of microalgae for phycoremediation and biomass production for sustainable biofuel production is a viable choice. Phycoremediation of As(III) and As(V) ions using microalgae was investigated in a two-staged batch reactor. Accumulation and toxicity of inorganic arsenic forms (As(III) and As(V)) to green microalgae Botryococcus braunii depend on environmental factors. Dissolved oxygen and pH cycles did not significantly differ due to the absence or presence of arsenic (either As(III) or As(V)) ions in the culture. Monod model was utilized for representing the growth kinetics of microalgae in pure media containing various concentrations of nitrate ions. Maximum specific growth rate and saturation constant were found to be 0.14788 d^?1 and 0.00105 g/L, respectively. With the increase in concentration of phosphate in growth medium, the growth of microalgae increased. Media with NaCl (1.0 g/L) and NaHCO₃ (1 g/L) resulted in higher maximum biomass concentration. Effect of coexisting ions on phycoremediation of As(III) and As(V) ions using microalgae was studied.     

以Neprilysin蛋白酶为靶标的药物筛选模型的建立及应用

目的:建立以蛋白酶Neprilysin(NEP)为靶点的高通量药物筛选模型,应用该模型筛选抑制剂。方法:利用毕赤酵母表达系统。构建重组质粒p PICZα-A-NEP,表达载体通过与酵母菌X-33基因组染色体发生同源重组,将外源基因整合于染色体后实现目的蛋白的表达。应用荧光共振能量转移法(FRET)检测蛋白酶活性,优化反应条件,建立药物筛选体系,筛选抑制剂。结果:成功构建表达载体p PICZα-A-NEP;建立了以NEP为靶标的药物筛选模型,获得模型反应动力学参数Vmax=3.6μM/s,Kcat/Km=4.5×105M-1s-1,测定模型Z-因子为0.89,说明体系稳定可用于以NEP为靶标的药物的高通量筛选;并用该模型对天然产物组分库进行筛选,在0.5mg/ml的药物浓度下,得到抑制率较高的药物为4种,并测得半数抑制浓度IC50值,其中MDCNCL01000242的IC50值最低,为(8.31±0.03)μg/ml。结论:建立的药物筛选模型较为理想,适用于NEP抑制剂的筛选,可促进药物的研发。     

Phytoremediation of mine tailings in temperate and arid environments

Phytoremediation is an emerging technology for the remediation of mine tailings, a global problem for which conventional remediation technologies are costly. There are two approaches to phytoremediation of mine tailings, phytoextraction and phytostabilization. Phytoextraction involves translocation of heavy metals from mine tailings to the plant shoot biomass followed by plant harvest, while phytostabilization focuses on establishing a vegetative cap that does not shoot accumulate metals but rather immobilizes metals within the tailings. Phytoextraction is currently limited by low rates of metal removal which is a combination of low biomass production and insufficiently high metal uptake into plant tissue. Phytostabilization is currently limited by a lack of knowledge of the minimum amendments required (e.g., compost, irrigation) to support long-term plant establishment. This review addresses both strategies within the context of two specific climate types: temperate and arid. In temperate environments, mine tailings are a source of metal leachates and acid mine drainage that contaminate nearby waterways. Mine tailings in arid regions are subject to eolian dispersion and water erosion. Examples of phytoremediation within each of these environments are discussed. Current research suggests that phytoextraction, due to high implementation costs and long time frames, will be limited to sites that have high land values and for which metal removal is required. Phytostabilization, due to lower costs and easier implementation, will be a more commonly used approach. Complete restoration of mining sites is an unlikely outcome for either approach.     

以淀粉为碳源衣康酸高产菌株的筛选

对土曲霉出发菌株进行紫外线诱变、LiCl诱变以及代谢终产物抗性菌株选育。代谢终产物抗性菌株选育是一种有效的遗传育种方法,能显著提高产酸量。得到一株代号为At394的菌株,以玉米淀粉部分水解糖为碳源,产酸量为53.9g/L,比出发菌株提高了42.6%。糖酸转化率为61.5%,为所有筛选菌株最高。用红外光谱进行结构分析证实所得产物为衣康酸。     

新的产弹性蛋白酶菌株的筛选与鉴定

本研究从秸秆中分离得到一株弹性蛋白酶高产菌, 并对该菌株进行鉴定, 以期为实现其工业化生产提供理论依据。采用酪蛋白(脱脂奶粉)进行初筛后, 以弹性蛋白(牛筋)进行复筛, 并对筛选结果进行检验, 然后对所得菌株结合形态、生理生化特性和16S rRNA基因序列进行分类鉴定, 得到一株弹性蛋白酶高产菌株LSF-97。结果显示, 菌株LSF-97与短小芽孢杆菌同源率达到100%, 形态及生理生化特征与模式菌也显示高度一致性, 故将其确定为短小芽孢杆菌。     

Accumulation and detoxification of lead ions in legumes

This study focuses on lead accumulation in roots, stems and leaves of three plant species of the Fabacea family: Vicia faba, Pisum sativum and Phaseolus vulgaris grown hydroponically in a medium supplemented with 1 mM concentration of lead. The largest amount of lead, up to 75 mg Pb/g dry weight, was accumulated in roots of P. vulgaris. The highest rate of Pb ions uptake from the medium took place during the first 10 h of incubation with lead and after 96 h of incubation lead content in the medium decreased by half. Thus, it was suggested that P. vulgaris could be used in rhizofiltration--the use of plant roots to absorb pollutants from water contaminated with lead. At the same time we studied the influence of lead on acid soluble thiol, glutathione, homoglutathione contents and the synthesis of phyto- and homophytochelatins in roots of V. faba, P. sativum and P. vulgaris grown hydroponically. Activation of the detoxicative-phytochelatin system was observed in the cytosol of root cells of the tested plants. This system was composed of phytochelatins (PCs) in roots of V. faba, homophytochelatins (hPCs) in P. vulgaris roots and both PCs and hPCs in P. sativum roots. The total content of PCs and hPCs in roots of P. sativum was very high and reached around 4800 (expressed in nmol SH x g(-1)FW) and induction of their synthesis occurred after only 2 h of treatment with 1 mM Pb.     

Biological Control of Groundnut Late Leaf Spot and Rust by Seed and Foliar Applications of a Powder Formulation of Pseudomonas fluorescens

Glasshouse and field trials were conducted to determine the efficacy of a talc-based powder formulation of Pseudomonas fluorescens strain Pf1 in controlling groundnut leaf spot ( Cercosporidium personatum ) and rust ( Puccinia arachidis ). Seed treatment with the talc-based powder formulation of the bacterium alone effectively reduced the severity of leaf spot and rust. When the treated seeds were sown in soil, the antagonist moved to the rhizosphere and multiplied well in it. Foliar application with the powder formulation effectively controlled the groundnut leaf spot and rust. P. fluorescens multiplied well in the phyllosphere after foliar application of powder formulation. Combined application of the P. fluorescens formulation to seed and foliage effectively controlled leaf spot and rust, and increased the pod yield in greenhouse and field tests.     

TTC-CaCO3复合平板法快速筛选丙酮酸高产菌株

设计出一种用于快速筛选丙酮酸高产菌株的方法。这是一种理性化筛选方法。其原理是菌落产生的丙酮酸与碳酸钙反应形成可溶性的丙酮酸钙而出现透明圈,比较透明圈直径可以直观的选择出产酸较多的菌株;TTC与ADH作用而显色,颜色的深浅与ADH活性呈正比,这样可监测丙酮酸向乙醇的转化,筛选出低转化率的菌株。通过此方法,筛选出产酸多、ADH酶活力弱、发酵副产物少的目的菌株。     

产丁醇芽孢杆菌的分离、筛选与鉴定

通过富集培养和分离纯化等过程,从种植怀地黄的土壤中分离得到一株产丁醇兼性厌氧细菌菌株C2。以7%的玉米醪液为原料总溶剂(丙酮、丁醇、乙醇,ABE)产量可达17.17g/L,其中丁醇11.2g/L,占65.2%;发酵玉米秸秆糖化液(总糖浓度为25g/L)产总溶剂量为3.64g/L,其中丁醇2.63g/L,占72.3%。形态学、生理生化及系统发育研究表明该菌株为革兰氏阳性芽孢杆菌(Bacillus),与B.vallismortis、B.atrophaeus和B.mojavensis亲缘关系最近。     

Foliar carbon isotope discrimination in Larix species and sympatric evergreen conifers: a global comparison

Larches (Larix spp.), deciduous conifers, occur in the northern hemisphere in cold-temperate and boreal climates – an environment normally thought to favor evergreen tree species. We compare foliar carbon isotope discrimination (Δ), instantaneous water use efficiency, total foliar nitrogen concentration, and specific leaf area (for a subset of sites) between Larix spp. and co-occurring evergreen conifers at 20 sites throughout the natural range of larches. Except for Larix occidentalis in the xeric Intermountain West, USA, Δ is significantly (P < 0.05) greater for larches than co-occurring evergreen conifers at 77% of the sites, suggesting that larches use water less efficiently. At elevations greater than 3000 m, the Δ of Larix spp. and co-occurring conifers converge, suggesting that water is not the limiting resource. Foliar nitrogen concentration and specific leaf area are two ecophysiological characteristics that are positively correlated with high photosynthetic capacity. Foliar nitrogen concentration is significantly greater for larches than evergreen conifers at 88% of the sites and specific leaf area is approximately three times greater for larches than co-occurring conifers. Future studies should examine the potential effect that global warming may have on the distribution of larch forests because the water use efficiency of larches is commonly less than co-occurring evergreen conifers and the boreal and high-latitude environments are likely to experience the greatest climate warming. Received: 23 May 1997 / Accepted: 28 October 1997     

Native Useful Plants of Chile: A Review and Use Patterns

Economic Botany - Native Useful Plants of Chile: A Review and Use Patterns. We compiled an inventory of the uses of the native flora of Chile by extracting uses cited in the literature until 2015....     

A computational investigation of the interaction between As3+ and deoxynucleotides

A successful aptamer biosensor for As³⁺ in aqueous solution indicated that deoxynucleotides could be a potential ligand for arsenic absorption. However, the interaction mechanism between aptamer and As³⁺ is still not clear. In this paper, a density functional method was applied to investigate the interactions between As³⁺ and four kinds of deoxynucleotides in different charge states. According to the binding energy, dGMP was the best monomer with four different binding modes, and dGMP^3–As³⁺ with the O atom in the phosphate group was calculated to be the most stable one. Moreover, the interaction energy increased when the charge of deoxynucleotide was increased, suggesting that a negative charge was advantageous for deoxynucleotides to absorb As³⁺. The atoms in molecules (AIM), localised orbital locator (LOL) and Charge decomposition analyses (CDA) confirmed that the bond between N atoms and As³⁺ were covalent interactions and that between O atoms and As³⁺ were dominated by electrostatic interactions. As the charge grew, the bond strength of both interactions increased. At the same time, O atom in the vicinity of nucleobases began to participate in the interaction with As³⁺, which was originally bonded to N atoms.     

牦牛源木聚糖酶产生菌的筛选和鉴定

目的以牦牛粪便为样本,筛选并鉴定产木聚糖酶菌株。方法利用碱提取法从玉米芯中提取木聚糖,以自制木聚糖为唯一碳源,从牦牛牛粪中筛选产木聚糖酶细菌,利用16S rDNA基因序列分析鉴定菌种,3,5-二硝基水杨酸法(DNS)测定其产酶能力并分析所产酶的酶学特性。结果筛选获得牦牛源产木聚糖酶类芽胞杆菌,所产木聚糖酶的最适反应条件为50℃、pH 8.0,在pH值为7.0或8.0以及温度50℃条件下,表现出较好的稳定性,Mn~(2+)对酶活力具有显著抑制作用,该菌最佳发酵时间为12 h,酶活最高达到1.2 U/mL。结论该菌所产木聚糖酶能够针对性地降解玉米芯木聚糖,在畜牧业和工业上有一定的应用价值。     

营养风险筛查NRS2002的临床应用观察

采用营养风险筛查2002(NRS2002),选取2012年1月至2012年12月在上海市第十人民医院呼吸内科、肝胆内科、神经内科、普通外科、脊柱外科的新入院住院患者进行营养风险筛查,并调查住院期间的营养支持状况及营养指标的变化。结果显示,共有750例患者入选,呼吸内科和神经内科营养风险最高均为42%,但存在营养风险的患者营养支持率分别为23.8%和31.7%,肝胆内科存在营养风险的患者营养支持率最高,但也仅为47.6%;营养风险≥3分的患者中体质指数(BMI)、血清前白蛋白(PA)、血红蛋白(HB)3个指标均低于营养风险<3分的患者,且存在统计学意义(p<0.05)。结果表明,NRS2002适用于住院患者营养风险筛查,存在营养风险的患者营养支持率普遍较低,相关营养指标可辅助判断营养状况。