不同改良措施对太子参根际土壤酚酸含量及特异菌群的影响

太子参为石竹科多年生草本植物,以根部入药,药用价值高,市场需求大,但其栽培过程中存在严重的连作障碍问题,连作导致产量品质严重下降,病虫害猖獗,探索太子参连作障碍形成的机制及其消减措施意义重大.本研究以广泛栽培的“柘参2号”为试验材料,采用土壤农化分析、高效液相色谱(HPLC)分析、荧光定量PCR(qPCR)等技术对不同连作年限或不同消减措施下太子参根际土壤的主要养分、酚酸含量动态及特异菌群变化进行分析.结果显示: 太子参连作导致产量显著下降,与正茬相比产量下降达43.5%,而水旱轮作和微生物菌肥处理可不同程度缓解其障碍效应.太子参连作土壤主要养分(如速效氮、速效磷、速效钾、全钾)未降反升,但导致土壤酸化.HPLC分析表明,太子参连作下或者随生长时期的推进,土壤酚酸类物质并未表现出明显的积累效应,膨大中期和收获期重茬土壤中大部分酚酸含量甚至低于正茬土壤.进一步荧光定量PCR分析发现,太子参连作导致前期分离筛选到的几类病原菌(如尖孢镰刀菌、踝节霉菌、Kosakonia sacchari)的绝对含量显著上升,而水旱轮作和微生物菌肥处理可有效降低3类病原菌的含量,改善微生态结构.综上认为,太子参连作障碍的发生并非由土壤养分匮乏或者酚酸持续积累直接造成,可能主要与连作下土传病原微生物的大量繁殖爆发有关,本研究结果为深入揭示太子参连作障碍的形成机制及消减修复机制提供了理论依据.     

贵州兴仁煤矿区农田土壤重金属化学形态及风险评估

为了解煤矿区周边农田土壤重金属污染状况,采集了贵州省兴仁县某典型煤矿区农田土壤样品64份,测定了土样中重金属(As、Cr、Pb、Zn、Cd、Hg、Cu、Ni)总量及各形态含量,采用单因子指数法、潜在生态风险指数法(Hkanson法)和风险评估编码法(RAC)对研究区主要土壤利用类型(水稻土、薏米地、植烟土和菜园土)中重金属进行潜在生态风险评估和环境风险评价.结果表明： 不同利用类型土壤中重金属含量除Zn外,其他元素均明显超过贵州省背景值.单因子指数法评价结果表明,As、Pb、Hg和Cu污染较为严重,均属重度污染.形态分析表明,土壤中重金属形态构成差异明显,酸可提取态As、酸可提取态Cd所占比例较高;Cr、Zn、Cu、Ni主要以残渣态为主;Pb主要以可还原态和残渣态为主;而Hg的酸可提取态、可还原态、可氧化态均占有相当比例,三者之和大于55%.重金属可利用度大小顺序为:As(63.6%)>Hg(57.3%)>Cd(56.4%)>Pb(52.5%)>Cu(45.7%)>Zn(32.8%)>Ni(26.2%)>Cr(13.2%).潜在生态风险指数表明,各类型土壤潜在生态风险(RI)〖JP2〗为:菜园土(505.19)>薏米地(486.06)>植烟土(475.33)>水稻土(446.86),均处于较高风险.风险评估编码法结果显示,As在水稻土、薏米地及植烟土中均处于高风险,在菜园土中处于中等风险;Cd、Hg均处于中等风险,Cr、Pb、Zn、Cu和Ni均处于低风险.因此,对该区域农田土壤进行管控时应重点考虑As、Cd和Hg污染.     

担载血管生长因子的乳液法纤维用于血管再生的研究

目的:制备担载血管生长因子(VEGF)的乳液法静电纺丝纤维膜,对其开展一系列表征,从而研究其血管再生的潜能。方法:通过W/O乳液法制备担载VEGF的静电纺丝纤维膜,并对其形态、力学性质进行表征。用VEGF ELISA分析方法对其体外释放动力学进行研究。运用CCK-8法检测乳液法静电纺丝纤维膜中VEGF的活性变化。结果:乳液法静电纺丝纤维膜呈现连通的三维网状结构,平均直径为1μm,模拟了细胞外基质(ECM),最大拉伸应力为3.03±0.66 M Pa,具有良好的抗拉伸能力,能够支持细胞的生长。乳液法纤维膜中VEGF在体外累积释放了14天,总释放量超过20000 pg,达到血管再生的有效浓度。CCK-8结果显示,乳液法纤维膜中的VEGF仍然保持较高的蛋白活性。结论:担载VEGF的乳液法静电纺丝纤维膜能够缓释出活性的蛋白,具有血管再生的潜能。     

Investigating core genetic-and-epigenetic cell cycle networks for stemness and carcinogenic mechanisms,and cancer drug design using big database mining and genome-wide next-generation sequencing data

Recent studies have demonstrated that cell cycle plays a central role in development and carcinogenesis. Thus, the use of big databases and genome-wide high-throughput data to unravel the genetic and epigenetic mechanisms underlying cell cycle progression in stem cells and cancer cells is a matter of considerable interest.

Real genetic-and-epigenetic cell cycle networks (GECNs) of embryonic stem cells (ESCs) and HeLa cancer cells were constructed by applying system modeling, system identification, and big database mining to genome-wide next-generation sequencing data. Real GECNs were then reduced to core GECNs of HeLa cells and ESCs by applying principal genome-wide network projection. In this study, we investigated potential carcinogenic and stemness mechanisms for systems cancer drug design by identifying common core and specific GECNs between HeLa cells and ESCs. Integrating drug database information with the specific GECNs of HeLa cells could lead to identification of multiple drugs for cervical cancer treatment with minimal side-effects on the genes in the common core. We found that dysregulation of miR-29C, miR-34A, miR-98, and miR-215; and methylation of ANKRD1, ARID5B, CDCA2, PIF1, STAMBPL1, TROAP, ZNF165, and HIST1H2AJ in HeLa cells could result in cell proliferation and anti-apoptosis through NFκB, TGF-β, and PI3K pathways. We also identified 3 drugs, methotrexate, quercetin, and mimosine, which repressed the activated cell cycle genes, ARID5B, STK17B, and CCL2, in HeLa cells with minimal side-effects.     

植物铝离子胁迫的研究方法综述

酸性土壤上,植物的生长受到很大的抑制,铝对植物的毒害是最主要的问题。为了揭示植物铝离子胁迫反应及其耐铝性的机理,科学家们进行了大量研究,取得了许多喜人的进展。根据前人研究,对植物铝离子胁迫的研究方法进行了综述。在试验材料的处理方面介绍了大田栽培、室外盆栽、室内盆栽、营养液栽培等方法;在耐铝性鉴定方面介绍了受害症状、根相对伸长率等直接鉴定法和化学染色、有机酸分泌量等间接鉴定法;在铝离子胁迫基因研究方面,介绍了基因定位技术、基因差异表达研究技术、蛋白质差异表达研究技术及转基因技术等研究方法。     

Development of a micelle‐enhanced high‐throughput fluorometric method for determination of niclosamide using a microplate reader

The present paper describes the development and validation of a simple and sensitive micelle‐enhanced high‐throughput fluorometric method for the determination of niclosamide (NIC) in 96‐microwell plates. The proposed method is based on the reduction of the nitro group of niclosamide to an amino group using Zn/HCl to give a highly fluorescent derivative that was developed simultaneously and measured at λ_em 444 nm after excitation at λ_ex 275 nm. Tween‐80 and carboxymethylcellulose (CMC) have been used as fluorescence enhancers and greatly enhanced the fluorescence by factors of 100–150%. The different experimental conditions affecting the fluorescence reaction were carefully investigated and optimized. The proposed method showed good linearity (r²≥ 0.9997) over the concentration ranges of 1–5 and 0.5–5 μg/ml with lower detection limits of 0.01 and 0.008 μg/ml and lower quantification limits of 0.04 and 0.03 μg/ml on using Tween‐80 and or CMC, respectively. The developed high‐throughput method was successfully applied for the determination of niclosamide in both tablets and spiked plasma. The capability of the method for measuring microvolume samples made it convenient for handling a very large number of samples simultaneously. In addition, it is considered an environmentally friendly method with lower consumption of chemicals and solvents.     

Inter-regional linkage analysis of industrial CO2 emissions in China: An application of a hypothetical extraction method

As the largest CO₂ emitter in the world, China has faced great pressure to mitigate its CO₂ emissions. Thus, issues related to CO₂ emissions in China have been widely studied. However, the industrial linkages of CO₂ emissions at the regional level have been less concerned. This study integrates hypothetical extraction method with the multi-regional input–output model, and investigates industrial CO₂ emission linkages of China at the regional level. Based on the data of China in 2007, which decomposes China into eight regions, this study first analyzes the production-based emission (PBE) and consumption-based emission (CBE) of each region. The PBE and CBE of 10 branches are then analyzed and decomposed into three parts. Finally, this study decomposes the externally produced embodied emission (EPEE) and internally produced embodied emission (IPEE) of Petrochemicals and Minerals in the East Coast, to illustrate how these two indicators of a branch affect other branches in the economy. Results show that regions with large PBE, such as coastal regions and Central, usually have large CBE, whereas Jing-jin has the smallest PBE and CBE. Branches such as Mining and Petrochemicals and Minerals, have large PBE and are net CO₂ emission exporters; while Construction and Other Services are net importers. According to the decomposition results of PBE and CBE, branches can be classified into four groups. The decomposed IPEE and EPEE of Petrochemicals and Minerals in the East Coast show that from the perspective of regions, CO₂ emissions this branch exports to and imports from East Coast are most. From the perspective of branches, decomposition of IPEE shows that Petrochemicals and Minerals in the East Coast exports a large amount of CO₂ emissions to Construction, while the decomposition results of EPEE show that the studied branch imports least CO₂ emissions from Construction. Policy implications deduced from this study are discussed.     

GSTaxClassifier: a genomic signature based taxonomic classifier for metagenomic data analysis

GSTaxClassifier (Genomic Signature based Taxonomic Classifier) is a program for metagenomics analysis of shotgun DNA sequences. The program includes

1. a simple but effective algorithm, a modification of the Bayesian method, to predict the most probable genomic origins of sequences at different taxonomical ranks, on the basis of genome databases;
2. a function to generate genomic profiles of reference sequences with tri-, tetra-, penta-, and hexa-nucleotide motifs for setting a user-defined database;
3. two different formats (tabular- and tree-based summaries) to display taxonomic predictions with improved analytical methods; and
4. effective ways to retrieve, search, and summarize results by integrating the predictions into the NCBI tree-based taxonomic information.

GSTaxClassifier takes input nucleotide sequences and using a modified Bayesian model evaluates the genomic signatures between metagenomic query sequences and reference genome databases. The simulation studies of a numerical data sets showed that GSTaxClassifier could serve as a useful program for metagenomics studies, which is freely available at http://helix2.biotech.ufl.edu:26878/metagenomics/.     

Oligomerization of H-pyrophosphatase and its structural and functional consequences

The H⁺-pyrophosphatase (H⁺-PPase) consists of a single polypeptide, containing 16 or 17 transmembrane domains. To determine the higher order oligomeric state of Streptomyces coelicolor H⁺-PPase, we constructed a series of cysteine substitution mutants and expressed them in Escherichia coli. Firstly, we analyzed the formation of disulfide bonds, promoted by copper, in mutants with single cysteine substitutions. 28 of 39 mutants formed disulfide bonds, including S545C, a substitution at the periplasmic side. The formation of intermolecular disulfide bonds suppressed the enzyme activity of several, where the substituted residues were located in the cytosol. Creating disulfide links in the cytosol may interfere with the enzyme's catalytic function. Secondly, we prepared double mutants by introducing second cysteine substitutions into the S545C mutant. These double-cysteine mutants produced cross-linked complexes, estimated to be at least tetramers and possibly hexamers. Thirdly, we co-expressed epitope-tagged, wild type, and inactive mutant H⁺-PPases in E. coli and confirmed the formation of oligomers by co-purifying one subunit using the epitope tag used to label the other. The enzyme activity of these oligomers was markedly suppressed. We propose that H⁺-PPase is present as an oligomer made up of at least two or three sets of dimers.     

Bridelionosides A-F: Megastigmane glucosides from Bridelia glauca f. balansae

The chemical investigation of leaves of Bridelia glauca f. balansae afforded six megastigmane glucosides, named bridelionosides A-F, along with seven known megastigmane glucosides. Their structures were determined by a combination of spectroscopic analyses and by application of the modified Mosher's method.