Analysis of gene regulatory networks of maize in response to nitrogen

Nitrogen (N) fertilizer has a major influence on the yield and quality. Understanding and optimising the response of crop plants to nitrogen fertilizer usage is of central importance in enhancing food security and agricultural sustainability. In this study, the analysis of gene regulatory networks reveals multiple genes and biological processes in response to N. Two microarray studies have been used to infer components of the nitrogen-response network. Since they used different array technologies, a map linking the two probe sets to the maize B73 reference genome has been generated to allow comparison. Putative Arabidopsis homologues of maize genes were used to query the Biological General Repository for Interaction Datasets (BioGRID) network, which yielded the potential involvement of three transcription factors (TFs) (GLK5, MADS64 and bZIP108) and a Calcium-dependent protein kinase. An Artificial Neural Network was used to identify influential genes and retrieved bZIP108 and WRKY36 as significant TFs in both microarray studies, along with genes for Asparagine Synthetase, a dual-specific protein kinase and a protein phosphatase. The output from one study also suggested roles for microRNA (miRNA) 399b and Nin-like Protein 15 (NLP15). Co-expression-network analysis of TFs with closely related profiles to known Nitrate-responsive genes identified GLK5, GLK8 and NLP15 as candidate regulators of genes repressed under low Nitrogen conditions, while bZIP108 might play a role in gene activation

The wheat LLM-domain-containing transcription factor TaGATA1 positively modulates host immune response to Rhizoctonia cerealis

Wheat (Triticumaestivum) is essential for global food security. Rhizoctonia cerealis is the causal pathogen of sharp eyespot, an important disease of wheat. GATA proteins in model plants have been implicated in growth and development; however, little is known about their roles in immunity. Here, we reported a defence role of a wheat LLM-domain-containing B-GATA transcription factor, TaGATA1, against R. cerealis infection and explored the underlying mechanism. Through transcriptomic analysis, TaGATA1 was identified to be more highly expressed in resistant wheat genotypes than in susceptible wheat genotypes. TaGATA1 was located on chromosome 3B and had two homoeologous genes on chromosomes 3A and 3D. TaGATA1 was demonstrated to localize in the nucleus, possess transcriptional-activation activity, and bind to GATA-core cis-elements. TaGATA1 overexpression significantly enhanced resistance of transgenic wheat to R. cerealis, whereas silencing of TaGATA1 suppressed the resistance. RT-qPCR and chromatin immunoprecipitation-qPCR results indicated that TaGATA1 directly bound to and activated certain defence genes in host immune response to R. cerealis. Collectively, TaGATA1 positively regulates immune responses to R. cerealis through activating expression of defence genes in wheat. This study reveals a new function of plant GATAs in immunity and provides a candidate gene for improving crop resistance to R. cerealis

Specific Release of Bacteriochlorophylls B800 of LH2 from Rhodobacter azotoformans Induced by Sodium Dodecyl Sulfate

The release behaviors of bacteriochlorophylls of peripheral light-harvesting complex LH2 from Rhodobacter azotoformans induced by sodium dodecyl sulfate (SDS) were investigated using absorption spectroscopy. The results indicated that bacteriochlorophylls of B800 band are released from their binding sites and transformed into free bacteriochlorophylls by incubating LH2 sample in 10 mmol.L-1 Tris-HCl (pH 8.0) buffer containing SDS of low concentration at room temperature. However, the bacteriochlorophylls of B850 band are not released. The dynamics of B800 release and free BChl formation induced by 0.08% (w/V) SDS can be well fitted by the monoexponential model. The rate constant of B800 release is nearly equal to that of free BChls formation. The release of both B800 and B850 of LH2 can be induced by high concentration SDS, simultaneously. The bacteriochlorophylls of B800 band can be completely transformed into free BChls, but not for B850. Although both of their release processes show monoexponential models in 1% SDS solution, the release rate constant of B850 is remarkably lower than that of B800 and close to that of free BChls formation.国家自然科学基金(No. 30970068)、国家科技基础条件平台建设(No. 2005DKA21209)、厦门大学近海海洋环境科学国家重点实验室高级访问学者基 金(No. MELRS0907)和山西省回国留学人员科研(No. 200713)资助项目

Microstructural Characteristics and Mechanical Properties of Water Cooling Bobbin-Tool Friction Stir Welded 6063-T6 Aluminum Alloy

In this study, a novel welding method called water cooling bobbin-tool friction stir welding (WBT-FSW) was developed. 4 mm-thick 6063-T6 aluminum alloy sheets were successfully jointed by WBT-FSW. Comparative studies on macro/microstructural characteristics and mechanical properties of the WBT-FSW and conventional bobbin-tool friction stir welding (BT-FSW) joints were carried out. The results indicated that the water mist cooling can significantly decrease the welding temperature and improve both the weld formation and the mechanical properties of the joint. The tensile strength of the WBT-FSW joint was 11.4% higher than that of BT-FSW joint

Pigments accumulation via light and oxygen in Rhodobacter capsulatus strain XJ-1 isolated from saline soil

A Rhodobacter capsulatus strain, designated XJ-1, isolated from saline soil, accumulated almost only one kind of bacteriochlorophyll a anaerobically in the light, aerobically in the light and dark, and the relative contents of the bacteriochlorophyll a were 44.61, 74.89, and 77.53% of the total pigments, respectively. A new purple pigment appeared only in aerobic-light grown cells, exhibited absorption maxima at 355, 389, 520, 621, and 755 nm, especially distinctly unusual peak at 621 nm, whereas vanished in anaerobic-light and in aerobic-dark culture. Spheroidene and OH–spheroidene predominated in anaerobic phototrophic cultures. Spheroidenone was the sole carotenoid when exposed to both light and oxygen. The second keto-carotenoids, OH–spheroidenone, presented only in aerobic-dark culture in addition to spheroidenone. Strain XJ-1 would be a good model organism for the further illustration of the regulation of bacteriochlorophyll biosynthesis gene expression in response to unique habitat

Anaerobic utilization of phenanthrene by Rhodopseudomonas palustris

National Natural Science Foundation of China [31070054]; Natural Science Foundation of Fujian Province [2010 J01209]; Key Laboratory of Urban Environment and Health, Institute of Urban Environment [KLUEH201005]A phenanthrene- utilizing bacterium was anaerobically isolated and identified as Rhodopseudomonas palustris. It tolerated up to 100 mg phenanthrene l(-1) and degraded 50% of 50 mg phenanthrene l(-1) over 10 days. The presence of phenanthrene caused a prolonged lag phase (2-3 days) in cell growth and affected the photopigments biosynthesis, while DMSO (the solvent for phenanthrene) had no impact on cell growth. The cell surface hydrophobicity of the isolate was also increased

Identification of Floral Scent Profiles in Bearded Irises

Bearded irises are ornamental plants with distinctive floral fragrance grown worldwide. To identify the floral scent profiles, twenty-seven accessions derived from three bearded iris, including Iris. germanica, I. pumila and I. pallida were used to investigate the composition and relative contents of floral scent components by headspace solid-phase microextraction (HS-SPME) and gas chromatography−mass spectrometry (GC-MS). A total of 219 floral scent components were detected in blooming flowers. The scent profile varied significantly among and within the three investigated species. Principal component analysis (PCA) indicated that terpenes, alcohols and esters contributed the most to the floral scent components and 1-caryophyllene, linalool, citronellol, methyl cinnamate, β-cedrene, thujopsene, methyl myristate, linalyl acetate, isosafrole, nerol, geraniol were identified as the major components. In a hierarchical cluster analysis, twenty-seven accessions could be clustered into six different groups, most of which had representative scent components such as linalool, citronellyl acetate, thujopsene, citronellol, methyl cinnamate and 1-caryophyllene. Our findings provide a theoretical reference for floral scent evaluation and breeding of bearded irises

A Visible-NIR Responsive Dye-Sensitized Solar Cell Based on Diatom Frustules and Cosensitization of Photopigments from Diatom and Purple Bacteria

Diatoms exhibit high solar energy harvesting efficiency due to their remarkably organized, hierarchical micro/nanoporous, light-trapping, and scattering frustules. At present, few studies focus on cosensitization of natural near-infrared dye to expand the spectral response of dye-sensitized solar cells. In this study, the diatom frustule-TiO2 (12 : 5) composite film was prepared and assembled it on the TiO2 electrode. Compared to the single TiO2 layer film, diatom frustule-TiO2 (12 : 5) composite film sensitized by diatom’s dye showed the conversion efficiency of 0.719%. To expand the light-harvesting response to near-infrared region spectra, the cosensitized dyes were used to fabricate the visible-near-infrared responsive dye-sensitized solar cells. The cosensitization diatom frustule-TiO2 (12 : 5) composite film exhibited two distinct absorption bands in the near-infrared region and reached a higher conversion efficiency of 1.321%, which was approximately 1.4 or 1.7 folds higher than that of cosensitization double-TiO2 film or single TiO2 layer film, respectively, and approximately 3.7 or 1.7 folds higher than that of the single TiO2 layer film sensitized by diatom dye or purple bacterial dye, respectively. The results showed that the combination between diatom frustule-TiO2 with cosensitization natural dyes could significantly improve the photoelectric performance of visible-near-infrared responsive dye-sensitized solar cells

Nano-MoS2/poly (3,4-ethylenedioxythiophene): Poly(styrenesulfonate) composite prepared by a facial dip-coating process for Li-ion battery anode

MoS2/poly (3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT: PSS) composite (MoS2/P) was prepared through a facial and environmental friendly dip-coating method by dispersing nanostructured MoS2 particles in PEDOT: PSS aqueous solution and subsequent filtering process. The characterization of XRD, FTIR, TGA, SEM and TEM revealed that the surface of rose-like MoS2 was homogeneously coated with a thin layer of PEDOT: PSS. After coating, MoS2/P composite showed an enhanced electric conductivity of 1.0 x 10(-1) S/cm, about 5 times of that (2.2 x 10(-2) S/cm) of the pristine MoS2. MoS2/P composite electrode exhibited significantly improved electrochemical performances such as cyclability and rate capability. Half-cell tests showed that MoS2/P composite electrode delivered a reversible capacity of 712 mAh g(-1) at a current density of 50 mA g(-1) and retained 81% capacity after 100 cycles. At a higher current density of 200/300 mA g(-1), it still retained a capacity of 439/363 mAh g(-1) respectively, as compared to 191/140 mAh g(-1) for the pristine MoS2. (C) 2013 Elsevier B. V. All rights reserved