径向流色谱分离纯化海藻多糖及其抗氧化活性比较分析

以裂片石莼、亨氏马尾藻和海萝3种海藻为原料,采用超声波辅助提取、分步醇沉得到7种组分粗多糖,利用径向流色谱分离纯化粗多糖,测定超氧阴离子、羟基自由基和ABTS 3种自由基体系下其抗氧化能力.结果表明:通过径向流处理,多糖回收率和蛋白脱除率分别可达97.79％和87.32％;7种海藻多糖组分均具有抗氧化活性,均随多糖浓度的增加而增加,马尾藻60％醇沉组分(SHP60)抗氧化活性最高,在其70μg·mL-1浓度时,对超氧阴离子自由基和羟基自由基清除率分别为74.34％和71.84％;同种海藻的中等分子量多糖组分的抗氧化活性较强.     

荔枝低分子量多糖的分离纯化及抗氧化吸湿保湿性能分析

为进一步开发和利用荔枝中的多糖成分,该文对荔枝低分子量多糖组分进行分离纯化,并对其理化性质、抗氧化和吸湿保湿性进行研究。采用超声波辅助提取、分级醇沉、DEAE-cellulose 52和Sephadex G-100柱分离纯化荔枝多糖;紫外-可见光谱扫描法、比旋光度法、渗透凝胶色谱法3种方法验证纯度;高效凝胶渗透色谱法测定相对分子量,高效阴离子交换色谱测定单糖组成;清除DPPH自由基和羟基自由基评价体外抗氧化活性;体外法测定吸湿保湿性。结果表明:荔枝多糖经分离纯化后获得组分荔枝多糖PLC-1,经3种方法验证PLC-1为精多糖,相对分子量为2.35×104 Da,是由半乳糖、鼠李糖、葡萄糖组成,摩尔比为:1.00∶3.52∶5.89。抗氧化活性研究结果表明PLC-1对DPPH和羟基自由基呈良好的量效关系,半数清除浓度IC50分别为0.41和0.31 mg/m L。吸湿保湿性的结果表明,PLC-1具有良好的吸湿和保湿性,在32 h时的吸湿率为58.3%,32 h时的失水率为45.3%,荔枝多糖PLC-1为具抗氧化和吸湿保湿活性的多糖,研究结果可为荔枝的深加工和进一步研究开发提供一定的理论基础。     

超声波辅助提取裂褶菌多糖及分离纯化的研究

本文研究了超声波辅助法分离纯化裂褶菌多糖的工艺条件。分别从超声时间、超声功率、液料比、提取时间和提取温度5个因素考察了对裂褶菌多糖提取率的影响,且在此条件下进行响应面优化。试验结果表明,在超声时间30min、超声功率200W、液料比40∶1和提取温度40℃时裂褶菌多糖提取率为69.56%。经DEAE纤维素-52色谱柱和葡聚糖凝胶G-100分离各得到2种组分,对其进行紫外-可见光光谱(UV)分析和红外光谱分析得出,裂褶菌多糖Sp G不含蛋白质或核酸,可能为含呋喃环的α构型的多糖。研究为裂褶菌多糖的开发利用提供理论依据。     

党参多糖的提取分离及其抗氧化性研究进展

党参是一种传统的中药材,其多糖成分被广泛研究并被认为具有多种生物活性。本文综述了党参多糖的提取分离方法及其抗氧化性的研究进展。党参多糖的提取方法包括传统的水煎法、醇沉法、酸碱法以及现代的超声波辅助提取法、微波辅助提取法、高压萃取法等,分离常用的有薄层色谱法、高效液相色谱法、凝胶过滤层析法和透析法这4种技术。而党参多糖的抗氧化性主要通过体外实验方法 （包括DPPH自由基清除法、 ABTS自由基清除法、过氧化氢清除法等）进行评价,其抗氧化性主要表现在清除自由基、抑制氧化酶活性、提高抗氧化酶活性等方面。     

南瓜籽多糖热水提取工艺优化及其抗氧化活性

为开发利用南瓜籽中多糖资源,基于前期水提醇沉制得南瓜籽多糖的研究基础上,该文进一步探讨了热水浸提法提取南瓜籽多糖工艺参数并对其结构进行了初步分析。结果表明:南瓜籽多糖的最佳提取条件为提取温度60℃、提取时间2.5 h、液料比40:1 m L/g,此条件下多糖得率的预测值为2.25%,实际验证值为2.18%。初步分析南瓜籽多糖由鼠李糖、阿拉伯糖、木糖、甘露糖、葡萄糖和半乳糖6种单糖组成,摩尔比为0.52∶0.88∶0.73∶0.14∶1.00∶1.12,不含糖醛酸,为中性杂多糖。体外抗氧化活性试验表明,南瓜籽多糖对DPPH·、·OH和O2-·3种自由基均具有一定的清除效果,多糖质量浓度为1.0 mg/m L时,清除率分别达到21.3%±0.14%、57.14%±0.28%和40.50%±0.64%。研究结果为后续南瓜籽多糖纯品制备、结构表征提供了基础,为提高南瓜籽相关保健品附加值提供了一定理论依据。     

铜藻多糖微波辅提工艺优化及其抗氧化活性研究

运用响应曲面法优化铜藻多糖(tong zao polysaccharide,TZP)微波辅助提取的工艺条件,利用分级醇沉法得到TZP30%、TZP60%和TZP80%3个多糖组分。并对其DPPH自由基、ABTS自由基、OH自由基和O2-自由基的清除能力及其还原力进行了研究。结果表明:铜藻多糖微波辅助提取的最佳条件为料液比1:65,提取温度72℃,提取时间39min,多糖提取率为12.02%(n=3);在试验浓度范围内,TZP30%组分对羟基自由基的清除能力最高达98.07%;TZP60%组分对DPPH自由基清除能力最高达85.01%;TZP80%组分对ABTS自由基清除能力较强,还原力较大。铜藻多糖具有较高的抗氧化活性,具有作为天然抗氧化剂的应用前景。     

羊胎盘提取剩余物发酵制备活性肽工艺及产物生物活性

为实现羊胎盘提取剩余物的高值化利用,该文以超速冻冻藏羊胎盘提取剩余物为原料,利用枯草芽孢杆菌对其进行生物降解制备生物活性肽。通过对发酵过程监控研究了发酵过程中蛋白酶活、产物的平均肽链长度、产物的抗氧化和免疫活性的变化,实现了可控制发酵羊胎盘提取剩余物制备免疫活性肽。研究结果表明:随着发酵时间的延长,蛋白酶活、水解度逐渐升高;平均肽链长度逐渐变小;产物的抗氧化活性和免疫活性均呈现先升高后降低的趋势。在发酵时间35 h下产物具有较好的抗氧化活性和免疫活性,产物的免疫活性与抗氧化活性均随浓度的增大而升高,发酵产物对淋巴细胞的刺激指数最高可达23.37%,发酵产物对1,1-二苯基-2-三硝基苯肼(DPPH:1,1-Diphenyl-2-picrylhydrazyl radical2,2-Diphenyl-1-(2,4,6-trinitrophenyl)hydrazyl)自由基清除率为0.667 mg/m L。超滤结果表明:不同分子量组分的发酵液生物活性有较大差异,其中3~10 k Da组分的免疫活性最高,≤3 k Da组分的抗氧化活性最高。各组分之间的生物活性与原样品相比不具有加和性但是具有明显的协同作用。研究结果为实现可控制发酵制备羊胎盘生物活性肽提供了参考。     

三叶青多糖提取工艺优化及单糖组成分析

为优化三叶青多糖的提取工艺,并分析其单糖组成,通过正交试验设计方法优选三叶青多糖的最佳提取工艺,同时,采用柱前衍生化-高效液相色谱法来测定单糖组成。结果表明:三叶青多糖的最佳提取工艺为料液体积比1∶25,提取2次,每次2.5 h,醇沉浓度70%。该方法对多糖提取率为7.40%;柱前衍生化-高效液相色谱法分析得三叶青多糖主要由甘露糖、鼠李糖、半乳糖醛酸、葡萄糖、岩藻糖、半乳糖、阿拉伯糖等单糖组成。本实验方法简单可行。     

亮菌多糖提取工艺优化及体外抗肿瘤活性研究

本研究进行了亮菌多糖水提、醇沉工艺条件优选并对其体外抗肿瘤活性进行了研究。以多糖含量为指标,设计正交试验考察料液比、浸提温度、浸提时间、浸提次数对亮菌多糖提取工艺的影响;以多糖得率为评价指标,选乙醇浓度、乙醇加入量、醇沉时间为考察因素,通过正交试验优选醇沉工艺;采用MTT法测定多糖对4种肿瘤细胞增殖的抑制作用。结果显示亮菌多糖最佳浸提工艺为料液比1：10,提取次数为2次,浸提温度100℃,时间6 h;最佳醇沉条件为加4倍量95%乙醇沉淀15 h;醇沉后多糖得率11.768%。活性测试结果显示ATPS对人红白血病细胞和人肺癌细胞株的生长具有抑制作用。优选的提取工艺条件稳定,可为ATPS的生产提供实验依据;亮菌多糖对体外肿瘤细胞的生长具有抑制作用。     

黑穗醋栗果实超声波降解多糖的结构及抗糖基化活性

为了充分利用黑穗醋栗果实中的多糖资源,该文对水提醇沉,大孔树脂纯化制得黑穗醋栗果实多糖进行超声波降解,并对分离纯化后得到的低分子量多糖的理化性质、结构特征和抗糖基化反应活性进行了研究。利用葡聚糖凝胶Sephadex G-100对降解多糖进行分离纯化,高效液相色谱法测定分子量,气相色谱法测定单糖组成,红外光谱、紫外光谱、刚果红试验和电镜扫描初步表征多糖结构。结果表明:黑穗醋栗果实降解多糖(BCP I)纯度为83.88%±0.76%;重均分子量为235 955 Da;BCP I为酸性杂多糖,单糖组成及物质量比为:半乳糖醛酸:鼠李糖:阿拉伯糖:甘露糖:葡萄糖:半乳糖=2.31:1.11:3.14:0.34:0.36:1.00。BCP I具有多糖的特征吸收峰,不含多酚、蛋白质和核酸;不具有三股螺旋结构,呈现片状不规则的形态。抗糖基化活性测定结果表明BCP I对糖基化反应3个阶段(Amadori产物形成阶段、二羰基化合物形成阶段和糖基化终产物形成阶段)产物的形成均表现出良好的抑制作用,抑制率随浓度与时间的增加而增大。最大抑制率分别为49.55%±0.79%,41.82%±0.72%和42.01%±0.13%,均高于对照氨基胍。研究结果可为后续深入探讨黑穗醋栗果实多糖结构与降血糖活性之间的构效关系提供理论基础。     

低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响

【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。     

Pasture Vegetation Elemental Analysis by Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing.     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Macroinvertebrates in North American tallgrass prairie soils: effects of fire, mowing, and fertilization on density and biomass

The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.     

Variation in quality parameters between and within 14 Nordic tree fruit and berry species

Abstract

A 3-year study was carried out to investigate quality parameters in 14 tree fruit and berry species grown in southern Norway. The species were blueberry, apple, aronia, sour cherry, sweet cherry, red raspberry, strawberry, blackcurrant, gooseberry, red currant and elderberry, harvested along with wild bilberry, cloudberry and lingonberry. Significant differences between species were identified for all quality parameters. The coefficient of variation between species was lowest for pH (12.5%), dry matter (18.9%) and soluble solids (25.3%), followed by titratable acids (59.3%), total phenolics (83.8%), antioxidant capacity FRAP (85.7%) and antiradical power by the DPPH-assay (97.8%), total monomeric anthocyanins (132%) and ascorbic acid (137%). Average coefficient of variation within species were lower and ranged from 4 (pH) to 62% (ascorbic acid). Only the FRAP values were significantly affected by harvesting year with lower levels in 2004 than in 2005 and 2006. There were significant interactions between species and harvesting year for dry matter, soluble solids, pH, ascorbic acid and FRAP. The results indicate generic ranges in composition within species independent upon growing location and climate, and the composition of the tree fruits and berries is not likely to deviate from these ranges. It is concluded that desirable composition of tree fruits and berries and their products should primarily be achieved by selection among species rather than searching fors broadened variation within individual species.     

Potassium Fixation and Release Characteristics in Rhizosphere and Nonrhizosphere Soils for a Rapeseed–Rice Cropping Sequence

Potassium (K) fixation and release in soil are important factors in the long-term sustainability of a cropping system. Changes in K concentration and characteristics of K fixation and release in rhizosphere and nonrhizosphere soils in the rapeseed (Brassica napus L.)–rice (Oryza sativa L.) rotation were investigated using a rhizobox system. The concentrations of different forms of K in both rhizosphere and nonrhizosphere soils decreased with plants compared to without plants, regardless of K fertilizer application. Potassium uptake by crops mainly came from the rhizosphere soil. In the treatment without K fertilizer (–K), the main form of K supplied by the soil to the crops was 1.0 mol L^?1 nitric acid (HNO₃) nonextractable K, followed by nonexchangeable K, and then exchangeable K. In the treatment with K fertilizer (+K), the main K forms supplied by the soil to the crops were exchangeable K and nonexchangeable K. The amount and rate of K fixation after one cycle of the rapeseed–rice rotation was greater in rhizosphere soil than in nonrhizosphere soil. The amount and rate of K fixation of soil in the +K treatment were significantly less than in the –K treatment. The cumulative amounts of K released with 1.0 mol L^?1 ammonium acetate (NH₄OAc) and 1.0 mol L^?1 HNO₃ extraction increased with the increasing numbers of extractions, but the K-releasing power of soil by successive extraction decreased gradually and finally became almost constant. The release of K was less in rhizosphere soil than in nonrhizosphere soil. The release of K in the +K treatment was similar to that in the –K treatment in rhizosphere soil, but the K release in nonrhizosphere soil was greater with the +K than the –K treatment. Overall, the information obtained in this study will be helpful in formulating more precise K fertilizer recommendations for certain soils.     

Electron donor and pH relationships for biologically enhanced dissolution of chlorinated solvent DNAPL in groundwater

Biologically enhanced dissolution offers a method to speed removal of chlorinated solvent dense non-aqueous-phase liquid (DNAPL) sources such as tetrachloroethene (PCE) and trichoroethene (TCE) from aquifers. Bioremediation is accomplished by adding an electron donor to the source zone where fermentation to intermediates leading to acetic acid and hydrogen results. The hydrogen and possibly acetic acid are used by dehalogenating bacteria to convert PCE and TCE to ethene and hydrochloric acid. Reductive dehalogenation is thus an acid forming process, and sufficient alkalinity must be present to maintain a near neutral pH. The bicarbonate alkalinity required to maintain pH above 6.5 is a function of the electron donor: 800 mg/L of bicarbonate alkalinity is sufficient to achieve about 1.2 mM TCE dechlorination with glucose, 1.7 mM with lactate, and a much higher 3.3 mM with formate. Laboratory studies indicate that in mixed culture, formate can be used as an electron donor for complete conversion to ethene, contrary to pure cultures studies indicating it cannot. Various strategies can be used to add electron donor to an aquifer for DNAPL dehalogenation while minimizing pH problems and excessive electron donor usage, including use of injection-extraction wells, dual recirculation wells, and nested injection-extraction wells.     

Biodiversity and ecogeography of wild Lactuca spp. in some European countries

Staff members of the Department of Botany of Palacký University in Olomouc and Gene Bank Department – Workplace Olomouc, Research Institute of Crop Production in Prague, Czech Republic, conducted an expedition in seven European countries (Austria, Czech Republic, France, Germany, Italy, the Netherlands, Switzerland) in August/September 1999 to collect wild Lactuca spp. germplasm and study its geographic distribution, ecology and biodiversity. During the mission, more than 600 locations were visited resulting in the collection of 602 seed samples (accessions) of wild Lactuca species and 13 seed samples of related genera (Chondrilla and Mycelis). Lactuca serriola f. serriola, L. serriola f. integrifolia, L. saligna and L. viminea subsp. chondrilliflora were prevalent in southern Europe (Italy, France), however, only L. serriola was common in central and western Europe (Austria, Czech Republic, Germany, Netherlands, Switzerland). The greatest diversity of Lactuca species was found in France, where also the most seed samples (165) were collected. The most characteristic habitats with a high density of Lactuca spp. populations were observed along roads and highways, grassy ditches, ruderal communities, and dust-heaps. Natural infections by powdery mildew (Erysiphe cichoracearum) and downy mildew (Bremia lactucae) on some wild Lactuca spp. were observed. Recent observations concerning the geographic distribution, population structure, habitats, and natural occurrence of diseases of Lactuca spp. are discussed. This assemblage of genetic resources of Lactuca spp. can serve as the basis of future studies of species diversification, spatial population structure, plant microevolution, domestication processes, and genetic variability of host-parasite interactions.     

Responses of native legume desert trees used for reforestation in the Sonoran Desert to plant growth-promoting microorganisms in screen house

Three slow-growing legume trees used for desert reforestation and urban gardening in the Sonoran Desert of Northwestern Mexico and the Southwestern USA were evaluated whether their growth can be promoted by inoculation with plant growth-promoting bacteria (Azospirillum brasilense and Bacillus pumilus), unidentified arbuscular mycorrhizal (AM) fungi (mainly Glomus sp.), and supplementation with common compost under regular screenhouse cultivation common to these trees in nurseries. Mesquite amargo (Prosopis articulata) and yellow palo verde (Parkinsonia microphylla) had different positive responses to several of the parameters tested while blue palo verde (Parkinsonia florida) did not respond. Survival of all tree species was over 80% and survival of mesquite was almost 100% after 10 months of cultivation. Inoculation with growth-promoting microorganisms induced significant effects on the leaf gas exchange of these trees, measured as transpiration and diffusive resistance, when these trees were cultivated without water restrictions.     

Increase in auxiliary photoprotective photosynthetic pigments in wheat seedlings induced by Azospirillum brasilense

Inoculation of wheat seedlings with the plant growth-promoting bacterium Azospirillum brasilense Cd was immobilized in alginate microbeads and, without applying any stress, significantly increased the quantity of several photosynthetic pigments, such as chlorophyll a, chlorophyll b, and the auxiliary photoprotective pigments violaxanthin, zeaxanthin, antheroxanthin, lutein, neoxanthin, and β-carotene. This resulted in greener plants with no apparent visible stress. After monitoring the quantity of photosynthetic pigments for 4 weeks, we observed that inoculated plants had higher quantities of pigments in shoot and stem. The greatest difference in the quantity of all pigments between inoculated and noninoculated plants occurred in the first week of growth. Regardless of treatment, the quantity of pigments in stems was three to four times less than the quantity of these pigments in shoots. Application of Azospirillum, either as liquid inoculant or as alginate microbeads, did not alter the positive effect of the bacteria on pigment production or the positive response of the plants towards A. brasilense Cd inoculation.