南美蟛蜞菊对除莠剂的胁迫反应及其化学防除

南美蟛蜞菊原产中、南美洲,目前成为危害农林生产、破坏生态系统和生物多样性的入侵植物.本文研究了南美蟛蜞菊对化学胁迫的反应和防除措施,结果表明:(1)盆栽的南美蟛蜞菊经不同浓度除莠剂处理后,叶片在短期内出现不同程度的伤害症状,且伤害作用随着浓度的增加而加重.至观察后期,1:200~1:600毒莠定和二氯吡啶酸溶液处理的植物完全枯死;1:200~1:800氟草烟溶液处理的植株完全枯死.(2)不同除莠剂处理后叶绿素含量明显下降,随着处理的处理浓度的提高,对叶绿素的危害程度逐渐加重.(3)不同除莠剂溶液处理后,叶片相对电导率均不同程度升高,且随着处理浓度的升高,相对电导率相应地越高,显示细胞膜受伤害程度越严重.(4)大田药物试验结果显示,三种除莠剂均能在一定的浓度梯度范围内起到防除作用,1:600的毒莠定和二氯吡啶酸溶液、1:800的氟草烟溶液可分别在10~15d时间内完全杀灭南美蟛蜞菊.     

Phosphate-solubilizing bacteria improve the phytoremediation efficiency of Wedelia trilobata for Cu-contaminated soil

In a controlled experiment, we assessed the effect of phosphate-solubilizing bacterium (PSB) on the soil metal (Cu²⁺) phytoremediation by Wedelia trilobata and examined the effect of the interaction of Cu contamination and PSB on the growth of W. trilobata. We also explored the effect of the interaction of Cu contamination and PSB on the soil microflora. The results showed that the removal efficiency of Cu from soil by W. trilobata increased with an increase in the concentration of PSB, and the translocation factors of Cu (i.e., leaf:root and stem:root) were both significantly upregulated by PSB. The PSB significantly promoted the growth of W. trilobata; however, the effect of the Cu–PSB interaction on the leaf net photosynthetic rate (Pn) of W. trilobata was not significant, whereas copper contamination had a significant negative influence on the soil microflora, PSB had a significant positive influence on the soil microflora. Thus, PSB improved the phytoremediation efficiency of W. trilobata in Cu-contaminated soil because of the positive influence on the soil microflora, improving soil quality, which then increased the growth of W. trilobata in Cu-contaminated soil. The vigorous growth of W. trlobata led to higher of Cu absorption and translocation from soil as the ultimate result.     

干旱和复水对入侵植物三裂叶蟛蜞菊叶片叶绿素荧光特性的影响

选取入侵植物三裂叶蟛蜞菊(Wedelia trilobata)及其本地近缘种蟛蜞菊(W. chinensis)为实验材料,比较干旱和复水后二者叶片的叶绿素荧光特性和抗氧化酶活性等生理指标的变化规律,探讨入侵种三裂叶蟛蜞菊对干旱的响应和生态适应性.结果发现,在自然干旱处理过程中,入侵种三裂叶蟛蜞菊与本地种蟛蜞菊相比土壤含水量下降较快,对它们叶片气孔形态的比较发现,干旱胁迫11d后三裂叶蟛蜞菊叶片气孔开度明显大于蟛蜞菊,这可能是导致其失水较快的原因之一.干旱胁迫11d后三裂叶蟛蜞菊的PSⅡ最大光能转化效率(Fv/Fm)降低了43.8%,而蟛蜞菊只降低了3.7%;同时,与蟛蜞菊相比,三裂叶蟛蜞菊的PSⅡ实际光化学量子产量(Yield)、表观光合电子传递速率(ETR)和光化学猝灭系数(qP)也表现出较大幅度的降低,说明三裂叶蟛蜞菊对干旱胁迫较敏感;但复水后,三裂叶蟛蜞菊能够较快地恢复到正常水平,且与本地种不存在显著差异.这主要是由于入侵种在遭受干旱胁迫时提高了对其过量激发能的热耗散能力以及超氧化物歧化酶(SOD)和抗坏血酸还原酶(APX)的活性,保护光合机构少受不可逆的损伤,使其在干旱胁迫解除后光合功能得以迅速恢复.研究结果初步表明三裂叶蟛蜞菊容易受到水分条件的限制,它向干旱地区扩散的可能性较小.     

南美蟛蜞菊毛状根诱导及其离体培养

为了探讨利用南美蟛蜞菊毛状根来改良其观赏性状和生产次生物质,研究了南美蟛蜞菊Wedelia trilobata(L.)A.S.Hitche毛状根的诱导及其离体培养过程中培养基N源、碳源、磷和钙的消耗变化。结果表明,发根农杆菌Agrobacterium rhizogenes ATCC15834感染南美蟛蜞菊幼嫩叶片外植体7d后从其叶片切口中脉处产生毛状根。毛状根能在无外源激素的培养基上自主生长。PCR扩增结果显示发根农杆菌Ri质粒的rol B和rol C基因已在南美蟛蜞菊毛状根基因组中插入、整合并得到表达。毛状根液体培养0~7d内处于生长迟滞期、7~21d为快速生长期、21d后进入生长平台期。在毛状根液体培养过程中培养基的蔗糖、硝态氮、PO43?、Ca2+被逐渐吸收和消耗,培养至7d时,蔗糖被消耗近50%;硝态氮含量只剩下起始硝态氮含量的5.8%;至35d时,蔗糖和硝态氮含量分别约为其起始浓度的3.39%和1.82%。与Ca2+浓度变化不同的是,培养基的无机磷被快速消耗,培养至7d时其浓度约为其起始浓度的1.76%;但培养至35d时培养基中仍残存有占起始浓度约61.3%的Ca2+。该结果为今后利用南美蟛蜞菊毛状根来改良其观赏性状和设计合适的培养基来规模培养生产其次生物质提供了可能性。     

外来植物南美蟛蜞菊、裂叶牵牛和五爪金龙的光合特性

对南美蟛蜞菊、裂叶牵牛和五爪金龙的光合生理特性进行研究 ,结果表明 :(1) 3种植物都具有较强的 CO2 固定能力 ,南美蟛蜞菊的净光合速率峰值达 2 2 .1μm ol/ (m2 · s) ,高于裂叶牵牛 (17.2 μmol/ (m2 · s) )和五爪金龙 (18.6 μmol/ (m2 · s) ) ;(2 ) 3种植物光合速率、蒸腾速率的日进程曲线呈“双峰”型 ,气孔导度变化规律与蒸腾速率相似 ,在中午前后均出现一定程度的下降 ;(3)暗呼吸速率曲线呈单峰型 ,在中午时出现高峰 ,暗呼吸速率大小次序为 :五爪金龙 >裂叶牵牛 >南美蟛蜞菊。(4 )南美蟛蜞菊的光饱和点为 15 31μm ol/ (m2· s) ,光补偿点为 2 0 .0 μmol/ (m2· s) ,而裂叶牵牛的光饱和点 114 6 μmol/ (m2· s) ,光补偿点39.3μmol/ (m2· s) ;五爪金龙的光饱和点 12 6 1μmol/ (m2· s) ,光补偿点 4 4 .1μm ol/ (m2· s) ,3种植物都表现为喜阳植物的特性 ,且对弱光条件的适应力也较强 ,其中尤以南美蟛蜞菊的有效光合辐射范围最广 ,光量子利用效率较高 ,具有很强忍耐强光及适应阴生环境的能力。该项研究有助于解释南美蟛蜞菊生长迅速、生产力高、竞争性强的生物学特点     

外源钙对镉胁迫下南美蟛蜞菊毛状根生长、抗氧化酶活性和镉吸收的缓解效应

为了探讨外源钙对重金属镉(Cd)缓解南美蟛蜞菊Wedelia trilobata毛状根毒害的生理机理,采用溶液培养法研究了重金属Cd单独及其与Ca组合对南美蟛蜞菊毛状根生长、抗氧化酶超氧化物岐化酶(SOD)和过氧化物酶(POD)活性及对Cd2+吸收的影响。结果表明,Cd≤50μmol/L时促进毛状根生长;高于100μmol/LCd则抑制其生长,使其侧根短小,根尖变褐或变黑。与对照相比,不同浓度Cd培养的毛状根POD活性、SOD活性和MDA含量都比对照明显提高,但高于100μmol/L Cd培养的毛状根可溶性蛋白含量均比对照降低。与仅添加200μmol/L或300μmol/L Cd的毛状根相比,Cd和10~30 mmol/L Ca组合培养可促进毛状根生长,使其主、侧根变粗;提高其可溶性蛋白含量;降低其MDA含量、POD活性及SOD活性。原子吸收分光光度法测定结果表明,南美蟛蜞菊毛状根能吸收和吸附重金属Cd2+,当Cd2+浓度为100μmol/L时毛状根对Cd2+的吸收量最大,而Cd2+浓度为300μmol/L时毛状根对Cd2+的吸附量最大。外源加入10~30 mmol/L Ca2+可显著减少毛状根对Cd2+的吸收和吸附,并可调节其抗氧化酶活性,降低其膜脂过氧化水平而解除重金属镉对毛状根生长的抑制或毒害。     

Light limitation and litter of an invasive clonal plant,Wedelia trilobata,inhibit its seedling recruitment

Background and Aims

Invasive clonal plants have two reproduction patterns, namely sexual and vegetative propagation. However, seedling recruitment of invasive clonal plants can decline as the invasion process proceeds. For example, although the invasive clonal Wedelia trilobata (Asteraceae) produces numerous seeds, few seedlings emerge under its dense population canopy in the field. In this study it is hypothesized that light limitation and the presence of a thick layer of its own litter may be the primary factors causing the failure of seedling recruitment for this invasive weed in the field.

Methods

A field survey was conducted to determine the allocation of resources to sexual reproduction and seedling recruitment in W. trilobata. Seed germination was also determined in the field. Effects of light and W. trilobata leaf extracts on seed germination and seedling growth were tested in the laboratory.

Key Results

Wedelia trilobata blooms profusely and produces copious viable seeds in the field. However, seedlings of W. trilobata were not detected under mother ramets and few emerged seedlings were found in the bare ground near to populations. In laboratory experiments, low light significantly inhibited seed germination. Leaf extracts also decreased seed germination and inhibited seedling growth, and significant interactions were found between low light and leaf extracts on seed germination. However, seeds were found to germinate in an invaded field after removal of the W. trilobata plant canopy.

Conclusions

The results indicate that lack of light and the presence of its own litter might be two major factors responsible for the low numbers of W. trilobata seedlings found in the field. New populations will establish from seeds once the limiting factors are eliminated, and seeds can be the agents of long-distance dispersal; therefore, prevention of seed production remains an important component in controlling the spread of this invasive clonal plant.     

Anti-Inflammatory Activity of Lauraceae Plant Species and Prediction Models Based on Their Metabolomics Profiling Data

The Lauraceae is a botanical family known for its anti-inflammatory potential. However, several species have not yet been studied. Thus, this work aimed to screen the anti-inflammatory activity of this plant family and to build statistical prediction models. The methodology was based on the statistical analysis of high-resolution liquid chromatography coupled with mass spectrometry data and the ex vivo anti-inflammatory activity of plant extracts. The ex vivo results demonstrated significant anti-inflammatory activity for several of these plants for the first time. The sample data were applied to build anti-inflammatory activity prediction models, including the partial least square acquired, artificial neural network, and stochastic gradient descent, which showed adequate fitting and predictive performance. Key anti-inflammatory markers, such as aporphine and benzylisoquinoline alkaloids were annotated with confidence level 2. Additionally, the validated prediction models proved to be useful for predicting active extracts using metabolomics data and studying their most bioactive metabolites.     

Differences in metabolite profile between blood plasma and serum

In metabolomic research, blood plasma and serum have been considered to possess similar compositions and properties. Their perceived equivalence has resulted in researchers choosing arbitrarily between serum and plasma for analysis. Here, routine serum and plasma were prepared and their low-molecular-weight compounds were determined using gas chromatography/time-of-flight mass spectrometry. Principal components analysis was applied to process the acquired data, and marked differences in metabolite profiles were observed between serum and plasma. Of the 72 identified compounds, 36 (50%) discriminate serum from plasma, with 29 and 7 metabolites showing a significantly higher abundance (t test, P < 0.05) in serum and plasma, respectively. Incubation of blood had distinct effects on the analyte peak areas, with the effects being more pronounced for plasma than for serum and more pronounced for a shorter incubation than for a longer incubation. These results highlight the importance in choosing serum or plasma as the analytical sample and in stipulating the incubation time. Because incubation affected the analyte peak areas less in serum than in plasma, we recommend serum as the sample of choice in metabolomic studies.     

烤烟硝酸盐含量与土壤养分的关系

采用多元统计分析方法研究了湖南烤烟叶片硝酸盐、亚硝酸盐含量与土壤养分之间的关系,结果表明：（1）典型相关分析证实烟叶硝酸盐、亚硝酸盐含量与土壤主要含氮养分（土壤全氮、碱解氮、铵态氮）及有机质含量的关系密切,与土壤其他养分含量的相关性较小,反映出在一定范围内,随着土壤含氮养分及有机质含量的增加,烟叶（亚）硝酸盐含量呈现增加的趋势,且土壤含氮养分及有机质含量与烟叶硝酸盐含量关系的密切程度高于与亚硝酸盐含量的相关;（2）根据烟叶硝酸盐、亚硝酸盐含量及其相应的植烟土壤养分（有机质、全氮、碱解氮、铵态氮）含量的大小,通过聚类分析把同一等级的烟叶样品分为高、中、低3类,不同类别相比较,有机质含量越高的土壤,其土壤全氮、碱解氮、铵态氮含量以及相应的烟叶硝酸盐、亚硝酸盐含量也越高,说明土壤有机质的高低,直接影响了土壤氮素的供应状况,进而影响了烟叶硝态氮含量的积累;（3）根据聚类分析结果建立了不同等级烟叶硝酸盐、亚硝酸盐含量高低的判别函数,可作为烟叶硝态氮含量在不同土壤肥力条件下判别归类的参考依据。     

Global analysis of metabolites in rat and human urine based on gas chromatography/time-of-flight mass spectrometry

Sediment in urine may contain low-molecular-weight compounds that should be included in the analysis. To date, no systematic investigation has addressed this issue. We investigated three primary factors that influence the extraction efficiency of metabolites during preparation of urine samples for metabolomic research: centrifugation, pH, and extraction solvents. Obtained with the use of gas chromatography/time-of-flight mass spectrometry (GC/TOFMS) technique and principal component analysis (PCA), our results indicate that (1) conventional centrifugation causes an apparent loss of some metabolites, indicating that urine samples for metabolomic research should not be centrifuged before procedures are undertaken to recover the metabolites; (2) pH adjustment has a large impact on the recovery of metabolites and is therefore not encouraged; (3) with design of experiment analysis, methanol and water yield the optimal extraction efficiency. Differences between rat and human urine were observed and are discussed. Ninety-nine metabolites identified in rat and human urine are presented. An efficient protocol is proposed for the pretreatment of urine samples.     

黄土丘陵区地形、土壤水分与草地的景观格局

在黄土丘陵区,地形因素和土壤水分是决定草地景观格局的主要因素,同时草地景观格局在不同尺度上影响着景观中的流.地形因素、土壤水分和草地结构在不同尺度上有着密切的联系,研究它们之间的关系对于了解生态系统的过程十分重要.针对黄土高原异质化的草地群落结构,选取黄土丘陵区经过20多年自然封育形成的天然草地,从坡面尺度对景观格局进行了调查研究,在地形因素、土壤水分和草地结构中选取了有代表性的指标14个,用多元统计分析对选取的指标进行了主成分分析和聚类分析.聚类分析将样方分成3种植被类型,不同植被类型的海拔、坡度、20～140cm土壤含水量以及物种丰富度和生物多样性存在显著性差异.相关分析表明：海拔对0～300cm土壤含水量影响显著;海拔对草地群落盖度,坡位、坡向对草地群落的物种丰富度和生物多样性有着重要影响;而草地群落的物种丰富度和生物多样性与0～100cm土层的含水量关系密切.     

花椒（Zanthoxylum bungeanum）凋落物分解过程中酚酸的释放及其浸提液对土壤化学性质的影响

应用分解网袋法研究了花椒凋落物分解过程中（0、10、30d和60d）酚酸的释放动态及凋落物浸提液对花椒林地土壤化学性质的影响。结果表明：花椒凋落物在分解过程中呈现出明显的毒性动态。凋落物分解的60d中,凋落物残留量在前30d内变化最大,30d后无显著变化;凋落物中酚酸含量随分解时间的延长,呈显著降低的趋势,且在分解10d时,酚酸释放量最大。4个分解动念的凋落物浸提液显著地改变了土壤好气性自生固氮菌、氨化细菌、好气性纤维素分解菌的数量和土壤pH值、酚酸含量、铵态氮、有效磷等化学性质。不同分解时间的凋落物浸提液均造成了土壤pH值的显著升高;分解10d的凋落物浸提液对土壤铵态氮的含量具有显著的降低作用,对土壤好气性自生固氮菌和氨化细菌的生长均具有显著的促进作用,而对好气性纤维素分解菌的生长具有抑制作用;分解60d的凋落物浸提液显著地降低了土壤酚酸含量,对土壤有效磷含量具有显著的升高作用,对好气性自生固氮菌的生长具有抑制作用,而对好气性纤维素分解菌的生长具有促进作用。     

Intracellular metabolic changes of Clostridium acetobutylicum and promotion to butanol tolerance during biobutanol fermentation

During the fermentation process, Clostridium acetobutylicum cells are often inhibited by the accumulated butanol. However, the mechanism underlying response of C. acetobutylicum to butanol stress remains poorly understood. This study was performed to clarify such mechanism through investigating the butanol stress-associated intracellular biochemical changes at acidogenesis phase (i.e., middle exponential phase) and solventogenesis phase (i.e., early stationary phase) by a gas chromatography-mass spectrometry-based metabolomics strategy. With the aid of partial least-squares-discriminant analysis, a pairwise discrimination between control group and butanol-treated groups was revealed, and 27 metabolites with variable importance in the projection value greater than 1 were identified. Under butanol stress, the glycolysis might be inhibited while TCA cycle might be promoted. Moreover, changes of lipids and fatty acids compositions, amino acid metabolism and osmoregulator concentrations might be the key factors involved in C. acetobutylicum metabolic response to butanol stress. It was suggested that C. acetobutylicum cells might change the levels of long acyl chain saturated fatty acids and branched-chain amino acids to maintain the integrity of cell membrane through adjusting membrane fluidity under butanol stress. The increased level of glycerol was considered to be correlated with osmoregulation and regulating redox balance. In addition, increased levels of some amino acids (i.e., threonine, glycine, alanine, phenylalanine, tyrosine, tryptophan, aspartate and glutamate) might also confer butanol tolerance to C. acetobutylicum. These results highlighted our knowledge about the response or adaptation of C. acetobutylicum to butanol stress, and would contribute to the construction of feasible butanologenic strains with higher butanol tolerance.     

六盘山小流域地形、植被特征与土壤水文物理性质的关系

利用多元统计方法,分析了六盘山分水岭沟小流域107个样地的地形、植被特征与土壤水文物理性质的关系。结果表明:饱和持水量、总孔隙度、毛管持水量、容重、石砾体积含量、非毛管孔隙度可作为土壤水文物理性质类型划分的6项重要指标,同时土壤毛管持水量还是一个敏感指标。将所有调查样地划分为土壤物理性质组间差别较大但组内接近的3组样地,发现各组样地的植被类型相近。土壤水文功能最好的第III组是以桦树和山杨为主的天然阔叶次生林样地,其主要分布在阴坡、中坡位;华北落叶松人工林为第Ⅱ组,其土壤水文功能次之;土壤水文功能最差的第Ⅰ组多是位于陡坡悬崖的华山松天然林及杂灌丛样地。土壤孔隙性受到地形和植被特征的共同影响,影响显著的地形特征主要是相对高程、坡向和坡位;植被特征主要是胸径、乔木高度和灌木层盖度。     

Development of a metabolomic approach based on urine samples and direct infusion mass spectrometry

The analysis of urine by direct infusion mass spectrometry suffers from ion suppression due to its high salt content and inter-sample variability caused by the differences in urine volume between persons. Thus, urine metabolomics requires a careful selection of the sample preparation procedure and a normalization strategy to deal with these problems. Several approaches were tested for metabolomic analysis of urine samples by direct infusion electrospray mass spectrometry (DI–ESI–MS), including solid phase extraction, liquid–liquid extraction, and sample dilution. In addition, normalization of results based on conductivity values and statistical treatment was performed to minimize sample variability. Both urine dilution and solid phase extraction with mixed mode sorbent considerably reduced the salt content in urine, providing comprehensive metabolomic fingerprints. Moreover, statistical data normalization enabled the correction of inter-sample physiological variability, improving the quality of results obtained. Therefore, high-throughput DI–ESI–MS fingerprinting of urine samples can be achieved with simple pretreatment procedures allowing the use of this noninvasive sampling in metabolomics. Finally, the optimized approach was tested in a pilot metabolomic investigation of urine samples from transgenic mice models of Alzheimer’s disease (APP/PS1) in order to illustrate the potential of the methodology.     

Mass spectrometric study of the Escherichia coli repressor proteins, IcIR and GcIR, and their complexes with DNA

In Escherichia coli, the IclR protein regulates both the aceBAK operon and its own synthesis. Database homology searches have identified many IclR-like proteins, now known as the IclR family, which can be identified by a conserved C-terminal region. We have cloned and purified one of these proteins, which we have named GclR (glyoxylate carboligase repressor). Although purification is straightforward, both the IclR and GclR proteins are difficult to manipulate, requiring high salt (up to 0.6 M KCl) for solubility. With the advent of nanospray ionization, we could transfer the proteins into much higher concentrations of volatile buffer than had been practical with ordinary electrospray. In 0.5 M ammonium bicarbonate buffer, both proteins were stable as tetramers, with a small amount of dimer. In a separate experiment, we found that IclR protein selected from a random pool a sequence which matched exactly that of the presumed binding region of the GclR protein, although IclR does not regulate the gcl gene. We designed a 29 bp synthetic DNA to which IclR and GclR bind, and with which we were able to form noncovalent DNA-protein complexes for further mass spectrometry analysis. These complexes were far more stable than the proteins alone, and we have evidence of a stoichiometry which has not been described previously with (protein monomer : dsDNA) = (4 : 1).     

Climate and litter quality differently modulate the effects of soil fauna on litter decomposition across biomes

Climate and litter quality have been identified as major drivers of litter decomposition at large spatial scales. However, the role played by soil fauna remains largely unknown, despite its importance for litter fragmentation and microbial activity. We synthesised litterbag studies to quantify the effect sizes of soil fauna on litter decomposition rates at the global and biome scales, and to assess how climate, litter quality and soil fauna interact to determine such rates. Soil fauna consistently enhanced litter decomposition at both global and biome scales (average increment ~ 27%). However, climate and litter quality differently modulated the effects of soil fauna on decomposition rates between biomes, from climate‐driven biomes to those where climate effects were mediated by changes in litter quality. Our results advocate for the inclusion of biome‐specific soil fauna effects on litter decomposition as a mean to reduce the unexplained variation in large‐scale decomposition models.     

新疆艾比湖胡杨凋落物与裸斑土壤代谢物差异比较

在干旱区荒漠胡杨疏林中,胡杨冠下存在草本植物极其稀疏的裸露斑块(简称裸斑)。为研究胡杨冠下裸斑形成化感机理,以裸斑内、外土壤以及冠下凋落物为研究对象,利用液相色谱-质谱联用技术对不同样本进行代谢组分析,使用PLS-DA鉴定并筛选各组代谢物差异,筛选出裸斑内、外土壤样本中差异显著的代谢物质及其代谢相关通路。研究结果显示,土壤样品中共鉴定出总代谢物质908种(615正,293负);凋落物样品中共鉴定出总代谢物质1291种(760正,531负)。通过筛选、注释并分类各组间差异显著的代谢物发现曲酸、微囊藻毒素、茶碱、辛二酸、花生四烯酸以及反式肉桂酸等化感物质相对定量值均为裸斑内显著大于裸斑外土壤;儿茶素、咖啡酸、吲哚、棕榈油酸、孜然醛、阿魏酸、反式肉桂酸、花生四烯酸、水杨醇以及香豆素等化感物质相对定量值均为凋落物样中显著大于土壤样品。以上胡杨潜在化感物质的积累可能增强植物的化感效应,导致胡杨冠下草本植物种子萌发及生长受到限制。