Showing papers by "Southwest University published in 2011"

Genome sequencing and comparative transcriptomics of the model entomopathogenic fungi Metarhizium anisopliae and M. acridum.

Abstract: Metarhizium spp. are being used as environmentally friendly alternatives to chemical insecticides, as model systems for studying insect-fungus interactions, and as a resource of genes for biotechnology. We present a comparative analysis of the genome sequences of the broad-spectrum insect pathogen Metarhizium anisopliae and the acridid-specific M. acridum. Whole-genome analyses indicate that the genome structures of these two species are highly syntenic and suggest that the genus Metarhizium evolved from plant endophytes or pathogens. Both M. anisopliae and M. acridum have a strikingly larger proportion of genes encoding secreted proteins than other fungi, while ∼30% of these have no functionally characterized homologs, suggesting hitherto unsuspected interactions between fungal pathogens and insects. The analysis of transposase genes provided evidence of repeat-induced point mutations occurring in M. acridum but not in M. anisopliae. With the help of pathogen-host interaction gene database, ∼16% of Metarhizium genes were identified that are similar to experimentally verified genes involved in pathogenicity in other fungi, particularly plant pathogens. However, relative to M. acridum, M. anisopliae has evolved with many expanded gene families of proteases, chitinases, cytochrome P450s, polyketide synthases, and nonribosomal peptide synthetases for cuticle-degradation, detoxification, and toxin biosynthesis that may facilitate its ability to adapt to heterogenous environments. Transcriptional analysis of both fungi during early infection processes provided further insights into the genes and pathways involved in infectivity and specificity. Of particular note, M. acridum transcribed distinct G-protein coupled receptors on cuticles from locusts (the natural hosts) and cockroaches, whereas M. anisopliae transcribed the same receptor on both hosts. This study will facilitate the identification of virulence genes and the development of improved biocontrol strains with customized properties.

Raman Spectroscopy of Few-Quintuple Layer Topological Insulator Bi2Se3 Nanoplatelets

Abstract: We report on Raman spectroscopy of few quintuple layer topological insulator bismuth selenide (Bi2Se3) nanoplatelets (NPs), synthesized by a polyol method. The as-grown NPs exhibit excellent crystalline quality, hexagonal or truncated trigonal morphology, and uniformly flat surfaces down to a few quintuple layers. Both Stokes and anti-Stokes Raman spectroscopy for the first time resolve all four optical phonon modes from individual NPs down to 4 nm, where the out-of-plane vibrational A(1g)(1) mode shows a few wavenumbers red shift as the thickness decreases below ~15 nm. This thickness-dependent red shift is tentatively explained by a phonon softening due to the decreasing of the effective restoring force arising from a decrease of the van der Waals forces between adjacent layers. Quantitatively, we found that the 2D phonon confinement model proposed by Faucet and Campbell cannot explain the red shift values and the line shape of the A(1g)(1) mode, which can be described better by a Breit–Wigner–Fano resonance line shape. Considerable broadening (~17 cm(–1) for six quintuple layers) especially for the in-plane vibrational mode E(g)(2) is identified, suggesting that the layer-to-layer stacking affects the intralayer bonding. Therefore, a significant reduction in the phonon lifetime of the in-plane vibrational modes is probably due to an enhanced electron–phonon coupling in the few quintuple layer regime.

Brassinolide Application Improves the Drought Tolerance in Maize Through Modulation of Enzymatic Antioxidants and Leaf Gas Exchange

Abstract: Brassinolides (BRs) are naturally occurring substances, which modulate plant growth and development events and have been known to improve the crop tolerance to abiotic stresses. In this study, possible role of exogenously applied brassinolide (BR) in alleviating the detrimental effects of drought in maize was evaluated in a rain-protected wire-house. Maize was subjected to drought at the start of tasseling for 6 days by withholding water application followed by foliar spray of BR (0.1 mg l−1) to assess the changes in growth, gas exchange, chlorophyll contents, protein, relative leaf water contents (RLWC), proline, malonialdehyde (MDA) and enzymatic antioxidants. Drought substantially reduced the maize growth in terms of plant height, leaf area and plant biomass. Moreover, substantial decrease in gas exchange attributes (net photosynthetic rate (A), transpiration rate (E), stomatal conductance (gs), water use efficiency (WUE), instantaneous water use efficiency (WUEi) and intercellular CO2 (Ci) was also recorded. However, exogenous application of BR remarkably improved the gas exchange attributes, plant height, leaf area, cobs per plant, seedling dry weight both under drought and well-watered conditions. BR-induced promotion in growth and physiological and metabolic activities were mediated through increased protein synthesis enabling maintenance of tissue water potential and activities of antioxidant enzymes lowering the lipid peroxidation under drought.

A self-assembled hierarchical nanostructure comprising carbon spheres and graphene nanosheets for enhanced supercapacitor performance

Abstract: A self-assembly approach is used to fabricate a hierarchical nanostructure using functionalized carbon spheres as nano-spacers to separate graphene nanosheets. The nanostructure significantly enhances capacitance of a graphene supercapacitor by more than 70%, while providing a universal method to self-assembling various carbons into hierarchical structures for energy conversion/storage systems.

Missing Value Estimation for Mixed-Attribute Data Sets

Abstract: Missing data imputation is a key issue in learning from incomplete data. Various techniques have been developed with great successes on dealing with missing values in data sets with homogeneous attributes (their independent attributes are all either continuous or discrete). This paper studies a new setting of missing data imputation, i.e., imputing missing data in data sets with heterogeneous attributes (their independent attributes are of different types), referred to as imputing mixed-attribute data sets. Although many real applications are in this setting, there is no estimator designed for imputing mixed-attribute data sets. This paper first proposes two consistent estimators for discrete and continuous missing target values, respectively. And then, a mixture-kernel-based iterative estimator is advocated to impute mixed-attribute data sets. The proposed method is evaluated with extensive experiments compared with some typical algorithms, and the result demonstrates that the proposed approach is better than these existing imputation methods in terms of classification accuracy and root mean square error (RMSE) at different missing ratios.

CeO2 nanoparticles/graphene nanocomposite-based high performance supercapacitor

Abstract: CeO2 nanoparticles/graphene nanocomposite is fabricated by depositing CeO2 nanoparticles onto three-dimensional graphene material and its supercapacitor performance is further investigated. The nanocomposite shows a high specific capacitance and power density, demonstrating a strong synergistic effect possibly contributed from improved conductivity of CeO2 and better utilization of graphene.

Spatiotemporal manipulation of auxin biosynthesis in cotton ovule epidermal cells enhances fiber yield and quality.

Abstract: The capacity of conventional breeding to simultaneously improve the yield and quality of cotton fiber is limited. The accumulation of the plant hormone indole-3-acetic acid (IAA) in cotton fiber initials prompted us to investigate the effects of genetically engineering increased IAA levels in the ovule epidermis. Targeted expression of the IAA biosynthetic gene iaaM, driven by the promoter of the petunia MADS box gene Floral Binding protein 7 (FBP7), increased IAA levels in the epidermis of cotton ovules at the fiber initiation stage. This substantially increased the number of lint fibers, an effect that was confirmed in a 4-year field trial. The lint percentage of the transgenic cotton, an important component of fiber yield, was consistently higher in our transgenic plants than in nontransgenic controls, resulting in a >15% increase in lint yield. Fiber fineness was also notably improved.

Reward and Motivation Systems: A Brain Mapping Study of Early-Stage Intense Romantic Love in Chinese Participants

Abstract: Early-stage romantic love has been studied previously in the United States and United Kingdom (Aron et al. [2005]: J Neurophysiol 94:327–337; Bartels and Zeki [2000]: Neuroreport 11:3829–3834; Ortigue et al. [2007]: J Cogn Neurosci 19:1218–1230), revealing activation in the reward and motivation systems of the brain. In this study, we asked what systems are activated for early-stage romantic love in Easterners, specifically Chinese participants? Are these activations affected by individual differences within a cultural context of Traditionality and Modernity? Also, are these brain activations correlated with later satisfaction in the relationship? In Beijing, we used the same procedure used by Aron et al. (Aron et al. [2005]: J Neurophysiol 94:327–337). The stimuli for 18 Chinese participants were a picture of the face of their beloved, the face of a familiar acquaintance, and a countback task. We found significant activations specific to the beloved in the reward and motivation systems, particularly, the ventral tegmental area and the caudate. The mid-orbitofrontal cortex and cerebellum were also activated, whereas amygdala, medial orbitofrontal, and medial accumbens activity were decreased relative to the familiar acquaintance. Self-reported Traditionality and Modernity scores were each positively correlated with activity in the nucleus accumbens, although in different regions and sides of the brain. Activity in the subgenual area and the superior frontal gyrus was associated with higher relationship happiness at 18-month follow-up. Our results show that midbrain dopamine-rich reward/motivation systems were activated by early-stage romantic love in Chinese participants, as found by other studies. Neural activity was associated with Traditionality and Modernity attitudes as well as with later relationship happiness for Chinese participants.

Methyl Jasmonate‐Induced Alteration in Lipid Peroxidation, Antioxidative Defence System and Yield in Soybean Under Drought

Abstract: Methyl jasmonate (MeJA), a plant-signalling molecule, is involved in an array of plant development and the defence responses. This study was conducted to explore the role of exogenous MeJA application in alleviating the adversities of drought stress in soybean (Glycine max L. Merrill.). Soybean plants were grown under normal conditions until blooming and were then subjected to drought by withholding irrigation followed by foliar application of (50 lm) MeJA. Drought stress substantially suppressed the yield and yield-related traits, whereas it accelerated the membrane lipid peroxidation. Nonetheless, substantial increase in activities of enzymatic antioxidants (superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT)), proline, relative water contents (RWC) with simultaneous decrease in membrane lipid peroxidation was observed in MeJA-treated plants under drought. These beneficial effects led to improvement in biological and grain yield, and harvest index under drought. Interestingly, MeJA application was also useful under well-watered conditions. These results suggest the involvement of MeJA in improving the drought tolerance of soybean by modulating the membrane lipid peroxidation and antioxidant activities.

Enhancing phosphorus availability in phosphorus-fertilized zones by reducing phosphate adsorbed on ferrihydrite using rice straw-derived biochar

Abstract: Purpose Biochar amendments can alter phosphorus (P) availability in soils, though the influencing mechanisms are not yet fully understood. This work investigated the adsorption and desorption of P on ferrihydrite (F, a Fe-oxide widely distributed in surface environments) in order to evaluate the interactions between P and Fe-oxide in the absence or presence of biochar (F or ferrihydrite–biochar (F–B) interaction) in soils.

Polyethyleneimine modified eggshell membrane as a novel biosorbent for adsorption and detoxification of Cr(VI) from water

Abstract: The polyethyleneimine (PEI) functionalized biosorbent which uses an eggshell membrane (ESM) as a model was synthesized based on the cross linking reaction between aldehydes in glutaraldehyde and functional groups such as amines and amides in ESM. The as-prepared biosorbent (PEI–ESM) strongly interacted with chromium(VI). After modification, the dynamic uptake capacity of the PEI–ESM increased by 105% compared with the control, and the maximum equilibrium adsorption capacity for Cr(VI) can reach about 160 mg g−1 with an initial pH of 3.0. The Langmuir adsorption isotherm was applicable to fit the removal process. Kinetics of the Cr(VI) removal were found to follow a pseudo-second-order rate equation. The results obtained by Raman spectroscopy and X-ray photoelectron spectroscopic analysis (XPS), performed on the as-prepared biosorbent before and after Cr(VI) adsorption, suggested that some of adsorbed Cr(VI) anions were reduced to Cr(III) in Cr2O3 or Cr(OH)3 during the sorption process, demonstrating that the PEI–ESM could detoxify Cr(VI). The developed biosorbent promises advantages such as low cost, high adsorption capacity, Cr(VI) detoxification, and environmental friendliness.

NiO/Graphene Composite for Enhanced Charge Separation and Collection in p-Type Dye Sensitized Solar Cell

Abstract: A p-type semiconductor photoelectrode in dye sensitized solar cells (DSCs) has a large optical band gap and high ionization potential but suffers from its intrinsically low hole transfer rate, thus...

Existence and multiplicity of solutions for Kirchhoff type equations

Abstract: In this paper, the existence and multiplicity of weak solutions are obtained for a class of Kirchhoff type problems with Dirichlet boundary value conditions by using the mountain pass theorem, the local linking theorem, the fountain theorem and the symmetric mountain pass lemma in critical point theory.

Fulvic Acid Application Improves the Maize Performance under Well‐watered and Drought Conditions

Abstract: Water deficit is perhaps the most severe threat to sustainable crop production in the conditions of changing climate. Researchers are striving hard to develop resistance against water deficit in crop plants to ensure food security for the coming generations. This study was conducted to establish the role of fulvic acid (FA) application in improving the performance of hybrid maize (Zea mays L.) under drought. Maize plants were grown under normal conditions till tasselling and were then subjected to drought by cessation of water followed by foliar application of FA (1.5 mg l−1). Drought stress disrupted the photosynthetic pigments and reduced the gas exchange leading to reduction in plant growth and productivity. Nonetheless, exogenous FA application substantially ameliorated the adversities of drought by sustaining the chlorophyll contents and gas exchange possibly by enhanced levels of antioxidant enzyme (superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT)) activities and proline. These beneficial effects yielded in terms of plant growth and allometry, and grain yield. It is interesting to note that FA application also improved the crop performance under well‐watered conditions. Hence, FA may be applied to improve the crop performance under drought and well‐watered conditions.

QTL analysis for yield components and kernel-related traits in maize across multi-environments

Abstract: Huangzaosi, Qi319, and Ye478 are foundation inbred lines widely used in maize breeding in China. To elucidate genetic base of yield components and kernel-related traits in these elite lines, two F2:3 populations derived from crosses Qi319 × Huangzaosi (Q/H, 230 families) and Ye478 × Huangzaosi (Y/H, 235 families), as well as their parents were evaluated in six environments including Henan, Beijing, and Xinjiang in 2007 and 2008. Correlation and hypergeometric probability function analyses showed the dependence of yield components on kernel-related traits. Three mapping procedures were used to identify quantitative trait loci (QTL) for each population: (1) analysis for each of the six environments, (2) joint analysis for each of the three locations across 2 years, and (3) joint analysis across all environments. For the eight traits measured, 90, 89, and 58 QTL for Q/H, and 72, 76, and 51 QTL for Y/H were detected by the three QTL mapping procedures, respectively. About 70% of the QTL from Q/H and 90% of the QTL from Y/H did not show significant QTL × environment interactions in the joint analysis across all environments. Most of the QTL for kernel traits exhibited high stability across 2 years at the same location, even across different locations. Seven major QTL detected under at least four environments were identified on chromosomes 1, 4, 6, 7, 9, and 10 in the populations. Moreover, QTL on chr. 1, chr. 4, and chr. 9 were detected in both populations. These chromosomal regions could be targets for marker-assisted selection, fine mapping, and map-based cloning in maize.