Rhizosphere soil bacterial communities and nitrogen cycling affected by deciduous and evergreen tree species

Deciduous and evergreen trees differ in their responses to drought and nitrogen (N) demand. Whether or not these functional types affect the role of the bacterial community in the N cycle during drought remains uncertain. Two deciduous tree species (Alnus cremastogyne, an N₂‐fixing species, and Liquidambar formosana) and two evergreen trees (Cunninghamia lanceolata and Pinus massoniana) were used to assess factors in controlling rhizosphere soil bacterial community and N cycling functions. Photosynthetic rates and biomass production of plants, 16S rRNA sequencing and N‐cycling‐related genes of rhizosphere soil were measured. The relative abundance of the phyla Actinobacteria and Firmicutes was higher, and that of Proteobacteria, Acidobacteria, and Gemmatimondaetes was lower in rhizosphere soil of deciduous trees than that of evergreen. Beta‐diversity of bacterial community also significantly differed between the two types of trees. Deciduous trees showed significantly higher net photosynthetic rates and biomass production than evergreen species both at well water condition and short‐term drought. Root biomass was the most important factor in driving soil bacterial community and N‐cycling functions than total biomass and aboveground biomass. Furthermore, 44 bacteria genera with a decreasing response and 46 taxa showed an increased response along the root biomass gradient. Regarding N‐cycle‐related functional genes, copy numbers of ammonia‐oxidizing bacteria (AOB) and autotrophic ammonia‐oxidizing archaea (AOA), N₂ fixation gene (nifH), and denitrification genes (nirK, nirS) were significantly higher in the soil of deciduous trees than in that of the evergreen. Structural equation models explained 50.2%, 47.6%, 48.6%, 49.4%, and 37.3% of the variability in copy numbers of nifH, AOB, AOA, nirK, and nirS, respectively, and revealed that root biomass had significant positive effects on copy numbers of all N‐cycle functional genes. In conclusion, root biomass played key roles in affecting bacterial community structure and soil N cycling. Our findings have important implications for our understanding of plants control over bacterial community and N‐cycling function in artificial forest ecosystems.     

Design,synthesis, and biological evaluation of novel carbazole derivatives as potent DNMT1 inhibitors with reasonable PK properties

The DNA methyltransferases (DNMTs) were found in mammals to maintain DNA methylation. Among them, DNMT1 was the first identified, and it is an attractive target for tumour chemotherapy. DC_05 and DC_517 have been reported in our previous work, which is non-nucleoside DNMT1 inhibitor with low micromolar IC₅₀ values and significant selectivity towards other S-adenosyl-_L-methionine (SAM)-dependent protein methyltransferases. In this study, through a process of similarity-based analog searching, a series of DNMT1 inhibitors were designed, synthesized, and evaluated as anticancer agents. SAR studies were conducted based on enzymatic assays. And most of the compounds showed strong inhibitory activity on human DNMT1, especially WK-23 displayed a good inhibitory effect on human DNMT1 with an IC₅₀ value of 5.0 µM. Importantly, the pharmacokinetic (PK) profile of WK-23 was obtained with quite satisfying oral bioavailability and elimination half-life. Taken together, WK-23 is worth developing as DNMT1-selective therapy for the treatment of malignant tumour.     

羊草草原枯枝落叶分解的研究——主要优势植物的分解速率和损失率

分解速率和损失率从不同侧面反映了枯枝落叶分解动态,羊草草原主要优势植物,羊草（Leymus chinensis),拂子茅（Calamagrostis epigejos),减蓬（Suaeda glauca),碱茅（Puccinellia tenuiflora),五脉山黎豆（Lathyrus quinqueneruivs),碱蒿（Artemisia anethifolia)分解速率的季节变化动态近似倒“V”字型,损失率的季节变化呈S型,反了枯枝落叶的失重情况,枯枝落叶的化学组成成分是造成不同种植物间分解差异的主要原因,特别是C／N比与分解快慢有密切关系,分解初期,枯枝落叶的损失符合指数衰减模型,枯枝落叶损失95％所需时间,羊草群落约为8．8a,杂类草群落约为9．7a,碱茅群落约为7．1a,碱蓬群落约为4．7a。     

弱氧化醋杆菌阿拉伯糖醇脱氢酶基因克隆及其在大肠杆菌中的表达

The partial genomic library of Acetobacter suboxydans was constructed using Yeast\| E.coli shuttle plasmid YEp352 as vector.Two positive transformants,designated as DH5α(pAD91) and DH5α(pAD98),were obtained by screening the growth of transformants on the agar plate in which D\|arabitol was used as the sole carbon source.The results of Southern blot and restriction endonuclease analysis showed that the two recombinants are identical.The insert is about 2.3kb.Arabitol dehydrogenase activity assay indic…     

Determination of cefazedone in human plasma by high performance liquid chromatography–tandem mass spectrometry: Application to a pharmacokinetic study on Chinese volunteers

A rapid, sensitive and simple high performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) method was developed for determination of cefazedone in human plasma using metronidazole as internal standard (IS). The chromatographic separation was achieved on an Ultimate XB-CN column (2.1 mm × 150 mm, 5 μm) with an isocratic mobile phase of acetonitrile and 20 mM ammonium acetate in 0.1% formic acid in water (15:85, v/v). Detection was performed using electrospray ionization in positive ion multiple reaction-monitoring mode (SRM), monitoring the transitions m/z 548.2 → 344.1 for cefazedone and m/z 172.2 → 128.1 for IS. Calibration curves were linear over a wide range of 0.20–401.12 μg/mL for cefazedone in plasma. The lower limit of quantification (LLOQ) was 0.20 μg/mL. The intra- and inter-day precisions were less than 7.2%. The average recovery of cefazedone was 90.8–91.0%. The validated method was successfully applied to the pharmacokinetic study of cefazedone in Chinese healthy volunteers following intravenous (IV) administration of 500, 1000 and 2000 mg cefazedone injection.     

Effects of size,neighbors, and site condition on tree growth in a subtropical evergreen and deciduous broad‐leaved mixed forest,China

Successful growth of a tree is the result of combined effects of biotic and abiotic factors. It is important to understand how biotic and abiotic factors affect changes in forest structure and dynamics under environmental fluctuations. In this study, we explored the effects of initial size [diameter at breast height (DBH)], neighborhood competition, and site condition on tree growth, based on a 3‐year monitoring of tree growth rate in a permanent plot (120 × 80 m) of montane Fagus engleriana–Cyclobalanopsis multiervis mixed forest on Mt. Shennongjia, China. We measured DBH increments every 6 months from October 2011 to October 2014 by field‐made dendrometers and calculated the mean annual growth rate over the 3 years for each individual tree. We also measured and calculated twelve soil properties and five topographic variables for 384 grids of 5 × 5 m. We defined two distance‐dependent neighborhood competition indices with and without considerations of phylogenetic relatedness between trees and tested for significant differences in growth rates among functional groups. On average, trees in this mixed montane forest grew 0.07 cm year^?1 in DBH. Deciduous, canopy, and early‐successional species grew faster than evergreen, small‐statured, and late‐successional species, respectively. Growth rates increased with initial DBH, but were not significantly related to neighborhood competition and site condition for overall trees. Phylogenetic relatedness between trees did not influence the neighborhood competition. Different factors were found to influence tree growth rates of different functional groups: Initial DBH was the dominant factor for all tree groups; neighborhood competition within 5 m radius decreased growth rates of evergreen trees; and site condition tended to be more related to growth rates of fast‐growing trees (deciduous, canopy, pioneer, and early‐successional species) than the slow‐growing trees (evergreen, understory, and late‐successional species).     

Quality,bioactivity study,and preclinical acute toxicity,safety pharmacology evaluation of PEGylated recombinant human endostatin (M2ES)

Endostar, a potent endogenous antiangiogenic factor, is wildly used in clinics. However, it was easily degraded by enzymes and rapidly cleared by the kidneys. To overcome these shortcomings, PEGylated recombinant human endostatin was developed. In this study, the purity of M₂ES was evaluated by silver stain and reversed‐phase high‐performance liquid chromatography. Ultraviolet spectrum was used to examine the structural of M₂ES and endostar. The bioactivity and antitumor efficacy of M₂ES were evaluated using an in vitro endothelial cell migration model and athymic nude mouse xenograft model of a heterogeneous lung adenocarcinoma, respectively. A preclinical study was performed to evaluate the acute toxicity and safety pharmacology in rhesus monkeys. The purity of M₂ES was more than 98%; PEG modification has no effect on endostatin structure. Compared with the control group, M₂ES dramatically retards endothelial cell migration and tumor growth. After intravenous (IV) infusions of M₂ES at a dose level of three and 75 mg/kg in rhesus monkeys, there was no observable serious adverse event in both acute toxicity and safety pharmacology study. On the basis of the quality and bioactivity study data of M₂ES and the absence of serious side effect in rhesus monkeys, M₂ES was authorized to initiate a phase I clinical trial.     

Urban development and sustainability challenges chronicled by a century of construction material flows and stocks in Tiexi,China

Construction materials are considerable forces of global environmental impacts, but their dynamics vis‐à‐vis urban development are poorly documented, in part because their long lifespans require elusive and sometimes nonexistent decade‐long high‐resolution data. This study analyzes the construction material flow and stock trends that shaped and were shaped by the development, decline, and renewal of the Tiexi district of Shenyang, a microcosm of China's urban transformations since the early 20th century. Chronicling building‐by‐building the material flows and stock accumulations involved in the buildup of this area, we shed light on the physical resource context of its socioeconomic history. We find that 42 million tonnes of construction materials were needed to develop the Tiexi district from 1910 to 2018, and 18 million tonnes of material outflows were generated by end‐of‐life building demolition. However, over 55% of inflows and 93% of outflows occurred since 2002 during a complete redevelopment of the district. Only small portions of end‐of‐life materials could have been reused or recycled because of temporal and typological mismatches of supply and demand and technical limitations. Our analysis reveals a dramatic decrease in median building lifetimes to as low as 6 years in the early 21st century. These findings contribute to the discussion of long‐term environmental efficiency and sustainability of societal development through construction and reflect on the challenges of urban renewal processes not only in China but also in other developing and developed countries that lost (or may lose) their traditional economic base and restructure their urban forms. This article met the requirements for a Silver/Silver JIE data openness badge described at http://jie.click/badges .     

嗜盐菌群对酸性金黄G的脱色特性和机理

【目的】为了获得能够在高盐环境下脱色偶氮染料的嗜盐菌群及其降解机理。【方法】采用富集驯化的方法获得一个嗜盐菌群,采用Illumina HiSeq2500测序平台对其群落结构进行测定;采用分光光度法测定了其降解特性;采用GC-MS和红外图谱分析了其降解机理;采用微核实验的方法比较了偶氮染料降解前后的毒性。【结果】该菌群在10%的盐度下,使100mg/L的酸性金黄G在8h内脱色。菌群主要由Zobellella、Rheinheimera、Exiguobacterium和Marinobacterium组成。最适宜的脱色条件是:pH=6,酵母粉为碳源,蛋白胨或硝酸钾作为氮源,盐度为1%–10%。酸性金黄G降解产物的毒性比降解前降低。酸性金黄G主要的降解产物是对氨基二苯胺和二苯胺。此外,该菌群还能使酸性大红GR和直接湖蓝5B等多种偶氮染料脱色,具有较好的脱色广谱性。【结论】获得了快速降解偶氮染料的嗜盐菌群及降解机理,为该嗜盐菌群应用于高盐印染废水的处理提供菌种资源和理论支持。