[Responses of ground-active arthropod community in Caragana shrub plantations to grazing management in desertified region.] / 干旱风沙区灌丛林地地面节肢动物群落对放牧管理的响应.

We investigated the community structure of ground-active arthropods as well as vegetation and soil properties in Caragana shrub plantations under grazing and exclosure management across spring, summer and autumn in Yanchi County of Ningxia in northern China. The aim of this study was to uncover the responses of ground-active arthropods in shrub plantations to grazing management in desertified regions. The results showed that: 1) plant height, soil fine sand content, and soil electrical conductivity were significantly lower, whereas soil bulk density and coarse sand were significantly higher in shrub plantations under grazing than exclosure. 2) There were 40 families from 13 orders captured. The dominant groups included Formicidae and Tenebrionidae families, which comprised 68.75% of the total individuals. There were four common groups occupying 20.82% of the total individuals. The remaining 34 groups were relatively rare, only accounting for 10.44% of the total. Across the three seasons, the composition of ground-active arthropod community was significantly different between grazing and exclosure, which indicates the sensitivity and adaptability of ground-active arthropods to environmental changes including grazing management and seasonal changes. 3) There was a significant effect of grazing on total abundance of ground-active arthropods in shrub plantations, with significantly higher values under grazing than under exclosure. There was no significant effect of grazing management on group richness and diversity of ground-active arthropods in shrub plantations. 4) There was a correlation of total abundance, evenness index and the Simpson index with plant abundance, vegetation height, soil moisture, soil pH and electrical conductivity. There was a significant correlation of the Shannon index with vegetation height, soil moisture and soil fine sand. Plant density, and soil pH, soil moisture and soil temperature were the key factors driving the structure of ground-active arthropod communities in shrub plantations under gra-zing management across seasons based on the partial RDA results. It was concluded that the variations of plant height, soil pH, soil moisture and soil temperature under grazing management could result in different ground-active arthropod taxon to changing habitats. The conservation effect of shrub on ground-active arthropod could reduce the negative impacts of grazing. Spring grazing could enhance ground-active arthropod abundances in shrub plantations. It was necessary to pay attention to prevention of insects which are caused by spring grazing in shrub plantations.

Extraordinary Room-Temperature Tensile Ductility of Pure Magnesium.

Room-temperature tensile behavior and associated deformation mechanisms of multiple-axial forged (MAFed) pure Mg has been investigated. The as-MAFed Mg, with a coarsely recrystallized structure, exhibited a balanced strain-hardening behavior with strain, resulting in extraordinary mechanical properties with high ultimate stress (~200 MPa) and extensive true strain (~0.30). The observation on the microstructural evolution suggests that the balanced strain-hardening behavior is correlated with de-twinning behavior cooperated with pyramidal dislocations at the plastic straining stage.

Improving the Classification Accuracy for Near-Infrared Spectroscopy of Chinese Salvia miltiorrhiza Using Local Variable Selection.

In order to improve the classification accuracy of Chinese Salvia miltiorrhiza using near-infrared spectroscopy, a novel local variable selection strategy is thus proposed. Combining the strengths of the local algorithm and interval partial least squares, the spectra data have firstly been divided into several pairs of classes in sample direction and equidistant subintervals in variable direction. Then, a local classification model has been built, and the most proper spectral region has been selected based on the new evaluation criterion considering both classification error rate and best predictive ability under the leave-one-out cross validation scheme for each pair of classes. Finally, each observation can be assigned to belong to the class according to the statistical analysis of classification results of the local classification model built on selected variables. The performance of the proposed method was demonstrated through near-infrared spectra of cultivated or wild Salvia miltiorrhiza, which are collected from 8 geographical origins in 5 provinces of China. For comparison, soft independent modelling of class analogy and partial least squares discriminant analysis methods are, respectively, employed as the classification model. Experimental results showed that classification performance of the classification model with local variable selection was obvious better than that without variable selection.

A New Local Modelling Approach Based on Predicted Errors for Near-Infrared Spectral Analysis.

Over the last decade, near-infrared spectroscopy, together with the use of chemometrics models, has been widely employed as an analytical tool in several industries. However, most chemical processes or analytes are multivariate and nonlinear in nature. To solve this problem, local errors regression method is presented in order to build an accurate calibration model in this paper, where a calibration subset is selected by a new similarity criterion which takes the full information of spectra, chemical property, and predicted errors. After the selection of calibration subset, the partial least squares regression is applied to build calibration model. The performance of the proposed method is demonstrated through a near-infrared spectroscopy dataset of pharmaceutical tablets. Compared with other local strategies with different similarity criterions, it has been shown that the proposed local errors regression can result in a significant improvement in terms of both prediction ability and calculation speed.

Local Strategy Combined with a Wavelength Selection Method for Multivariate Calibration.

One of the essential factors influencing the prediction accuracy of multivariate calibration models is the quality of the calibration data. A local regression strategy, together with a wavelength selection approach, is proposed to build the multivariate calibration models based on partial least squares regression. The local algorithm is applied to create a calibration set of spectra similar to the spectrum of an unknown sample; the synthetic degree of grey relation coefficient is used to evaluate the similarity. A wavelength selection method based on simple-to-use interactive self-modeling mixture analysis minimizes the influence of noisy variables, and the most informative variables of the most similar samples are selected to build the multivariate calibration model based on partial least squares regression. To validate the performance of the proposed method, ultraviolet-visible absorbance spectra of mixed solutions of food coloring analytes in a concentration range of 20-200 µg/mL is measured. Experimental results show that the proposed method can not only enhance the prediction accuracy of the calibration model, but also greatly reduce its complexity.

The CodY regulator is essential for virulence in Streptococcus suis serotype 2.

The main role of CodY, a global regulatory protein in most low G + C gram-positive bacteria, is in transcriptional repression. To study the functions of CodY in Streptococcus suis serotype 2 (S. suis 2), a mutant codY clone named ∆codY was constructed to explore the phenotypic variation between ∆codY and the wild-type strain. The result showed that the codY mutation significantly inhibited cell growth, adherence and invasion ability of S. suis 2 to HEp-2 cells. The codY mutation led to decreased binding of the pathogen to the host cells, easier clearance by RAW264.7 macrophages and decreased growth ability in fresh blood of Cavia porcellus. The codY mutation also attenuated the virulence of S. suis 2 in BALB/c mice. Morphological analysis revealed that the codY mutation decreased the thickness of the capsule of S. suis 2 and changed the surface structures analylized by SDS-PAGE. Finally, the codY mutation altered the expressions of many virulence related genes, including sialic acid synthesis genes, leading to a decreased sialic acid content in capsule. Overall, mutation of codY modulated bacterial virulence by affecting the growth and colonization of S. suis 2, and at least via regulating sialic acid synthesis and capsule thickness.

Wheat TaNPSN SNARE homologues are involved in vesicle-mediated resistance to stripe rust (Puccinia striiformis f. sp. tritici).

Subcellular localisation of SNAREs (soluble N-ethylmaleimide-sensitive factor attachment protein receptors) and their ability to form SNARE complexes are critical for determining the specificity of vesicle fusion. NPSN11, a Novel Plant SNARE (NPSN) gene, has been reported to be involved in the delivery of cell wall precursors to the newly formed cell plate during cytokinesis. However, functions of NPSN genes in plant-pathogen interactions are largely unknown. In this study, we cloned and characterized three NPSN genes (TaNPSN11, TaNPSN12, and TaNPSN13) and three plant defence-related SNARE homologues (TaSYP132, TaSNAP34, and TaMEMB12). TaSYP132 showed a highly specific interaction with TaNPSN11 in both yeast two-hybrid and bimolecular fluorescence complementation (BiFC) assays. We hypothesize that this interaction may indicate a partnership in vesicle trafficking. Expressions of the three TaNPSNs and TaSYP132 were differentially induced in wheat leaves when challenged by Puccinia striiformis f. sp. tritici (Pst). In virus-induced gene silencing (VIGS) assays, resistance of wheat (Triticum aestivum) cultivar Xingzi9104 to the Pst avirulent race CYR23 was reduced by knocking down TaNPSN11, TaNPSN13 and TaSYP132, but not TaNPSN12, implying diversified functions of these wheat SNARE homologues in prevention of Pst infection and hyphal elongation. Immuno-localization results showed that TaNPSN11 or its structural homologues were mainly distributed in vesicle structures near cell membrane toward Pst hypha. Taken together, our data suggests a role of TaNPSN11 in vesicle-mediated resistance to stripe rust.

Evaluation of recombinant proteins of Haemophilus parasuis strain SH0165 as vaccine candidates in a mouse model.

The recently completed genome sequence of Haemophilus parasuis strain SH0165 allowed us to screen putative OMPs for the development of recombinant vaccines. The objective of this study was to evaluate the immunogenicity and protective efficacy of three OMPs of H. parasuis. Three putative OMPs (SmpA, YgiW and FOG) were cloned, expressed and purified by Ni affinity chromatography using nitriloacetic acid resin. Mice were immunized either individually (individual protein, IP) or synergistically (synergistic protein, SP) with the recombinant proteins. A significant increase in IgG titer was detected in all protein-immunized mice. Isotyping studies revealed that the antibodies produced were predominantly IgG2a-type, indicating a predominant Th1 response. A significant increase was observed in IL-2, IL-4 and IFN-γ levels in the culture supernatants of splenocytes isolated from immunized mice. Furthermore, mice were challenged intraperitoneally with 6×10(9)CFU (5×LD(50)) of highly virulent homologous serovar 5 strain (SH0165) or 7.0×10(9) CFU (5×LD(50)) of the heterologous serovar 4 strain (MD0322) at fourteen days after the last immunization. All of the recombinant proteins enhanced survival and reduced histopathological lesions. Our results indicated that the three OMPs showed protection both individually and synergistically against infection with the highly virulent H. parasuis in mice.

Trigger factor of Streptococcus suis is involved in stress tolerance and virulence.

Streptococcus suis serotype 2 is an important zoonotic pathogen that causes serious diseases such as meningitis, septicemia, endocarditis, arthritis and septic shock in pigs and humans. Little is known about the regulation of virulence gene expression in S. suis serotype 2. In this study, we cloned and deleted the entire tig gene from the chromosome of S. suis serotype 2 SC21 strain, and constructed a mutant strain (Δtig) and a complementation strain (CΔtig). The results demonstrated that the tig gene, encoding trigger factor from S. suis serotype 2 SC21, affects the stress tolerance and the expression of a few virulence genes of S. suis serotype 2. Deletion of the tig gene of S. suis serotype 2 resulted in mutant strain, ΔTig, which exhibited a significant decrease in adherence to cell line HEp-2, and lacked hemolytic activity. Tig deficiency diminishes stresses tolerance of S. suis serotype 2 such as survive thermal, oxidative and acid stresses. Quantification of expression levels of known S. suis serotype 2 SC21 virulence genes by real-time polymerase chain reaction in vitro revealed that trigger factor influences the expression of epf, cps, adh, rpob, fbps, hyl, sly, mrp and hrcA virulence-associated genes. ΔTig was shown to be attenuated in a LD50 assay and bacteriology, indicating that trigger factor plays an important part in the pathogenesis and stress tolerance of. S. suis serotype 2 infection. Mutant ΔTig was 100% defective in virulence in CD1 mice at up to 107 CFU, and provided 100% protection when challenged with 107 CFU of the SC21 strain.

Isolation, structure determination and antibacterial activities of succinamide conjugate diacid from Acinetobacter sp. BJ-L.

Strain BJ-L was isolated from the a water sample taken from Xiao Yue River in Beijing and identified as Acinetobacter sp. BJ-L based on the study of its morphology, physiology, biochemistry and 16S rRNA gene sequence. A new antimicrobial substance was produced after the strain was incubated in potato extract medium at 15°C for 72 h. The antimicrobial substance was sequentially purified by reduced pressure condensation, EtOAc extract, and silica gel column chromatography. The structure of the antimicrobial substance was elucidated as succinamide conjugate diacid (SCD) by spectroscopic data interpretation. Structure analysis indicated that SCD is a novel compound and that it could inhibit the growth of some tested bacterial strains with the MIC of 2mg/ml, such as Staphylococcus aureus, Bacillus subtilis, Enterobacter aerogenes and Escherichia coli. Moreover, no obvious toxicity has been found on cultured HUVEC cells with different concentrations of SCD at 5, 10, 15, and 20mg/ml.

Identification of a novel angiogenin inhibitor 1 and its association with hyaluronidase of Streptococcus suis serotype 2.

To characterize the role of hyaluronidase (Hyl) of Streptococcus suis serotype 2 (S. suis 2), the hylA gene that encodes Hyl was cloned, expressed and purified. A murine brain cDNA library was used to screen for interacting proteins of Hyl. Employing the yeast two-hybrid system, a novel murine ribonuclease, angiogenin inhibitor 1 (AI1), which shares 93% homology with porcine AI1, was shown to interact with Hyl in yeast. Through co-immunoprecipitation assays, the interaction between AI1 and Hyl was further confirmed. Transcription and translation products of the identified cDNA were detected in both normal cells and S. suis 2-infected cells. AI1 was found to localize mainly in the cytoplasm of 293T cells. These results suggested that the identified protein AI1 might be involved in the pathogenesis of meningitis through interaction with Hyl of S. suis 2.

Dimeric guaianolides and sesquiterpenoids from Artemisia anomala.

A new dimeric guaianolide (8) and a new glaucolide (3), a seco-guaiaretic acid (4), two guaianolides (6 and 7), and five known sesquiterpene lactones (1, 2, 5, 9, and 10) were isolated from the aerial part of Artemisia anomala. Their structures were determined on the basis of chemical and spectroscopic analysis. In addition, their cytotoxic activities against five human cancer cell lines and anti-COX-2 effects in vitro were evaluated.

Contribution of glutamine synthetase to the virulence of Streptococcus suis serotype 2.

Streptococcus suis serotype 2 (S. suis 2) is an important pathogen, responsible for diverse diseases in swine and human. In this study, we investigated the role of the glutamine synthetase (GlnA) in the pathogenesis of S. suis 2 in mice. To assess the contribution of glutamine synthetase (GlnA) to the virulence of S. suis 2, an knockout mutant (DeltaglnA) unable to produce GlnA was constructed, and the virulence level of wild-type (WT) SC19 and the DeltaglnA mutant strain were compared in an in vitro adherence assay and murine infection models. The data showed that DeltaglnA mutant exhibited a significant decrease in adherence to the epithelial cells HEp-2. The DeltaglnA mutant strain was attenuated and could reduce mortality and morbidity in murine infection models. Furthermore, organ cultures showed that GlnA plays a role in the colonization of the specific organs involved in S. suis infection. Functional complementation of the glnA gene into the knockout mutant DeltaglnA or incubated with extracellular glutamine restored its ability to adhere to the epithelial cells HEp-2. These findings suggested that glnA is required for the full virulence in S. suis 2. Therefore, the DeltaglnA mutant was considered as an attenuated mutant.

The orphan response regulator RevSC21 controls the attachment of Streptococcus suis serotype-2 to human laryngeal epithelial cells and the expression of virulence genes.

Streptococcus suis-2 is an important zoonotic pathogen that causes serious diseases such as meningitis, septicemia, endocarditis, arthritis and septic shock in pigs and humans. Little is known about the regulation of virulence gene expression in S. suis-2. In the present study, we characterized an orphan transcriptional regulator, designated RevSC21. The RevSC21 gene was cloned and the sequence was determined. Deletion of the revSC21 gene of S. suis-2 yielded a mutant strain, SC211, which exhibited a significant decrease in adherence to cell line Hep-2, and lacked hemolytic activity. Quantification of expression levels of known S. suis-2 SC21 virulence genes by real-time PCR in vitro and in vivo revealed that RevSC21 influences the expression of mrp, ef, sly, fbps, sod, rpob, gyra hyl, cps and gapdh virulence-associated genes. SC211 was shown to be attenuated in a 50% lethal dose assay and bacteriology, indicating that RevSC21 plays an important part in the pathogenesis of S. suis-2 infection. Mutant SC211 was 100% defective in virulence in CD1 mice at up to 10(7) CFU, and provided 100% protection when challenged with 10(7) CFU of the SC21 strain.

Two new coumarin glycosides from Peucedanum praeruptorum.

Two new coumarin glycosides, praerosides VI (1) and VII (2), were isolated from the roots of Peucedanum praeruptorum Dunn. Their structures were elucidated by chemical reaction and NMR spectroscopic methods.

1H and 13C NMR assignments for two new angular furanocoumarin glycosides from Peucedanum praeruptorum.

Two novel angular-type furanocoumarin glycosides, peucedanoside A (1) and peucedanoside B (2), along with a known compound apterin (3), were isolated from the roots of Peucedanum praeruptorum Dunn. Their chemical structures were determined by MS, NMR spectroscopy and chemical analysis. Complete assignments of the 1H and 13C NMR spectroscopic data were achieved by 1D and 2D NMR experiments including DEPT, HSQC, HMBC and ROESY.

[Studies on xanthones from herbs of Polygala telephioides].

OBJECTIVE: To study the chemical constituents from the whole plants of Polygala telephioides. METHOD: Compounds were isolated by repeated silica gel and Sephadex LH -20 column chromatography, and their structures were determined by spectral analysis and physicochemical properties. RESULT: Six xanthones were isolated from P. telephioides, and their structures were identified as 1, 3, 7-trihydroxyxanthone (1), 1, 7-dihydroxy-3-methoxyxanthone (2), 1, 3-dihydroxyxanthone (3), 1, 7-dihydroxyxanthone (4), 1-methoxy-2, 3-methylenedioxyxanthone (5) and 1, 7-dimethoxyxanthone (6). CONCLUSION: All the compounds were obtained from this plant for the first time.

New diterpenoids from Semiaquilegia adoxoides.

Two new ent-kaurane-type diterpenoids, E-semiaquilegin (1) and Z-semiaquilegin (2), together with eight known compounds (3-10) were isolated from the dried roots of Semiaquilegia adoxoides (DC.) Makino. The structures of compounds 1 and 2 were elucidated mainly by 2D NMR techniques including 1H-1H COSY, HSQC, HMBC, NOESY as 16alpha-hydroxy-ent-kaurane-17,20-di-(3,4-dihydroxy-E-cinnamoyl) ester and its (Z)-isomer.

Complete assignments of 1H and 13C NMR spectral data for a novel diterpenoid from Semiaquilegia adoxoides.

Semiaquilegoside A (1), a new diterpenoid, was isolated from the roots of Semiaquilegia adoxoides. Its chemical structure was established as 3beta, 11- dihydroxy-12-O-beta-D-glucopyranosyl-8,11,13-abietatrien-6-one through spectroscopic techniques and chemical analysis.

Triterpene saponins from the leaves of Ilex kudingcha.

Nine new triterpene saponins, ilekudinosides K-S (1-9), and eight known triterpene saponins were isolated from the 70% ethanol extract of the leaves of Ilex kudingcha. The new saponins were characterized as 3-O-alpha-L-rhamnopyranosyl(1-->2)-beta-D-glucopyranosyl-alpha-kudinlactone (1), 3-O-beta-D-glucopyranosyl(1-->3)-alpha-L-arabinopyranosyl-beta-kudinlactone (2), 3-O-alpha-L-rhamnopyranosyl(1-->2)-alpha-L-arabinopyranosyl-gamma-kudinlactone (3), 3-O-beta-D-glucopyranosyl(1-->2)-beta-D-glucopyranosyl-alpha-kudinlactone (4), 3-O-beta-D-glucopyranosyl(1-->2)-alpha-L-arabinopyranosyl-alpha-kudinlactone (5), 3-O-beta-D-glucopyranosyl(1-->3)-alpha-L-arabinopyranosyl-alpha-kudinlactone (6), 3-O-alpha-L-rhamnopyranosyl(1-->2)-beta-D-glucopyranosyl-beta-kudinlactone (7), 3-O-alpha-L-rhamnopyranosyl(1-->2)-alpha-L-arabinopyranosyl-beta-kudinlactone (8), and 3-O-alpha-L-rhamnopyranosyl(1-->2)-beta-D-glucopyranosyl-gamma-kudinlactone (9), respectively. The structures and stereochemistry of compounds 1-9 were elucidated by spectroscopic data interpretation and chemical degradation.