Magnetite microspheres have wide applications in industry and biomedicine. The control of the particle size and size distribution is critical in accurately controlling the chemical and physical properties of the magnetic nanoparticles. Here an efficient microwave-controlled synthesis of Fe3O4/P(St-AA) microspheres was reported. We found that the reaction rate was accelerated and the size distribution was narrowed with the microwave-assisted synthesis. The size of the microspheres can be controlled by the feeding concentration of the sodium dodecyl benzene sulfonate surfactant with diameters ranging from 200~400 nm. Meanwhile, the magnetic microspheres exhibit superparamagnetic properties with no hysteresis at the low applied magnetic field, which is important for their application in magnetic field-driven applications.

Converting carbon dioxide into high-value-added formic acid as a basic raw material for the chemical industry via an electrochemical process under ambient conditions not only alleviates greenhouse gas effects but also contributes to effective carbon cycles. Unfortunately, the most commonly used Pd-based catalysts can be easily poisoned by the in situ formed minor byproduct CO during the carbon dioxide reduction reaction (CRR) process. Herein, we report a facile method to synthesize highly uniformed PdAg alloys with tunable morphologies and electrocatalytic performance via a simple liquid synthesis approach. By tuning the molar ratio of the Ag+ and Pd2+ precursors, the morphologies, composition, and electrocatalytic activities of the obtained materials were well-regulated, which was characterized by TEM, XPS, XRD, as well as electrocatalytic measurements. The CRR results showed that the as-obtained Pd3Ag exhibited the highest performance among the five samples, with a faradic efficient (FE) of 96% for formic acid at −0.2 V (vs. reference hydrogen electrode (RHE)) and superior stability without current density decrease. The enhanced ability to adsorb and activate CO2 molecules, higher resistance to CO, and a faster electronic transfer speed resulting from the alloyed PdAg nanostructure worked together to make great contributions to the improvement of the CRR performance. These findings may provide a new feasible route toward the rational design and synthesis of alloy catalysts with high stability and selectivity for clean energy storage and conversion in the future.

The high expense, poor stability, and low abundance of platinum (Pt) catalysts on earth greatly handicaps its further application. Alloying Pt with other metals is an alternate idea, however, as a promising catalyst should be synthesized on a large scale, one important goal is that the morphologies and electrocatalytic activities of the as-obtained electrocatalysts can maintain the same, even when the precursor ratio is varied. In addition, according to the Le Chatellier's principle as more earth-abundant precursors were used can accelerate the transforming efficiency of noble metal during the synthesis. Unfortunately, no current research has reached this goal, we herein report a facile two-step method for the synthesis of three-dimensional CuPt alloys via galvanic replacement between the noble Pt precursor and pre-synthesized copper (Cu) nanocubes in a liquid system free of capping agent. Further investigation proved that the morphologies can be regulated via changing the reaction temperature, while the composition of precursors does not affect the morphologies evolutions match well with the industrial demand. The CuPt alloys obtained at 80 degrees C (denoted as CuPt-80) exhibited superior activities towards both HER and MOR reaction when compared with CuPt-60, CuPt-100, Pt nanocrystals (Pt NCs) and 20% Pt/C. This work enriched the application of Le Chatellier's principle and provides a promising way for the rational design and synthesis of efficient and robust catalysts for sustainable energy conversion.

Progressive solute-rich polymer phase transitions provide pathways for achieving ordered supramolecular assemblies. Intrinsically disordered protein domains specifically regulate information in biological networks via conformational ordering. Here we consider a molecular tagging strategy to control ordering transitions in polymeric materials and provide a proof-of-principle minimal peptide phase network captured with a dynamic chemical network.

A S6-symmetric triarylamine-based macrocycle (i.e., hexaaza[16]paracyclophane), decorated with six lateral amide functions, is synthesized by a convergent and modular strategy. This macrocycle is shown to undergo supramolecular polymerization in o-dichlorobenzene, and its nanotubular structure is elucidated by a combination of spectroscopy and microscopy techniques, together with X-ray scattering and molecular modeling. Upon sequential oxidation, a spectroelectrochemical analysis of the supramolecular polymer suggests an extended electronic delocalization of charge carriers both within the macrocycles (through bond) and between the macrocycles along the stacking direction (through space).

Triarylamine molecules appended with crown-ethers or carboxylic moieties form self-assembled supramolecular channels within lipid bilayers. Fluorescence assays and voltage clamp studies reveal that the self-assemblies incorporating the crown ethers work as single channels for the selective transport of K+ or Rb+. The X-ray crystallographic structures confirm the mutual columnar self-assembly of triarylamines and crown-ethers. The dimensional fit of K+ cations within the 18-crown-6 leads to a partial dehydration and to the formation of alternating K+ cation-water wires within the channel. This original type of organization may be regarded as a biomimetic alternative of columnar K+-water wires observed for the natural KcsA channel. Supramolecular columnar arrangement was also shown for the triarylamine-carboxylic acid conjugate. In this latter case, stopped-flow light scattering analysis reveals the transport of water across lipid bilayer membranes with a relative water permeability as high as 17 mu m s(-1).

Histone acetylation plays a critical role in controlling chromatin structure, and reactive oxygen species (ROS) are involved in cell cycle progression. To study the relationship between histone acetylation and cell cycle progression in plants, sodium butyrate (NaB), a histone deacetylase (HDAC) inhibitor that can cause a significant increase in histone acetylation in both mammal and plant genomes, was applied to treat maize seedlings. The results showed that NaB had significant inhibition effects on different root zones at the tissue level and caused cell cycle arrest at preprophase in the root meristem zones. This effect was accompanied by a dramatic increase in the total level of acetylated lysine 9 on histone H3 (H3K9ac) and acetylated lysine 5 on histone H4 (H4K5ac). The exposure of maize roots in NaB led to a continuous rise of intracellular ROS concentration, accompanied by a higher electrolyte leakage ratio and malondialdehyde (MDA) relative value. The NaB-treated group displayed negative results in both TdT-mediated dUTP nick end labelling (TUNEL) and γ-H2AX immunostaining assays. The expression of topoisomerase genes was reduced after treatment with NaB. These results suggested that NaB increased the levels of H3K9ac and H4K5ac and could cause preprophase arrest accompanied with ROS formation leading to the inhibition of DNA topoisomerase.

Template-directed polymerization reactions enable the accurate storage and processing of nature's biopolymer information. This mutualistic relationship of nucleic acids and proteins, a network known as life's central dogma, is now marvellously complex, and the progressive steps necessary for creating the initial sequence and chain-length-specific polymer templates are lost to time. Here we design and construct dynamic polymerization networks that exploit metastable prion cross-β phases. Mixed-phase environments have been used for constructing synthetic polymers, but these dynamic phases emerge naturally from the growing peptide oligomers and create environments suitable both to nucleate assembly and select for ordered templates. The resulting templates direct the amplification of a phase containing only chain-length-specific peptide-like oligomers. Such multi-phase biopolymer dynamics reveal pathways for the emergence, self-selection and amplification of chain-length- and possibly sequence-specific biopolymers.

Organisms are constantly exposed to environmental stimuli and have evolved mechanisms of protection and adaptation. Various effects of nanoparticles (NPs) on crops have been described and some results confirm that NPs could enhance plant growth at the physiological and genetic levels. This study comparatively analysed the effect of carbon nanotubes (CNTs) on rice growth. The results showed that single-wall CNTs were located in the intercellular space while multi-wall CNTs penetrated cell walls in roots. CNTs could promote rice root growth through the regulation of expression of the root growth related genes and elevated global histone acetylation in rice root meristem zones. These responses were returned to normal levels after CNTs were removed from medium. CNTs caused the similar histone acetylation and methylation statuses across the local promoter region of the Cullin-RING ligases 1 (CRL1) gene and increased micrococcal nuclease accessibility of this region, which enhanced this gene expression. The authors results suggested that CNTs could cause plant responses at the cellular, genetic, and epigenetic levels and these responses were independent on interaction modes between root cells and CNTs.

Plant roots mainly consist of division, elongation and maturation regions. Histone modifications of chromatin play a vital role in plant cell growth and differentiation. However, there has been no systematic attempt to investigate the distribution patterns of histone modifications in the different plant root zones. In this study, histone H3 acetylation (H3K9ac), histone H4 acetylation (H4K5ac), and histone H3 methylation (H3K4me2, H3K4me3, H3K9me1, H3K9me2, and H3K27me2) levels and distribution patterns were examined in the root meristem, elongation and maturation zones of maize primary roots. Overall, the cells of the maturation zone displayed the highest level of multiple histone modifications. The lowest level of histone modification was detected in the root meristem. H3K9ac was enriched in the euchromatin and nucleoli of most nuclei from the elongation and Published online: April 10, 2014 Lijia Li State Key Laboratory of Hybrid Rice College of Life Sciences, Wuhan University Wuhan 430072 (PR China) E-Mail ljli @ whu.edu.cn Shibin He State Key Laboratory of Cotton Biology College of Life Sciences, Henan University Kaifeng 475004 (PR China) E-Mail sbhe @ henu.edu.cn © 2014 S. Karger AG, Basel 1424–8581/14/1433–0179$39.50/0 www.karger.com/cgr S.Y. and Q.Z. contributed equally to this work.

Simple sequence repeat (SSR) markers are widely used for genome mapping, genetic diversity characterization and medical diagnosis. The fast isolation by AFLP of sequence containing repeats (FIASCO) is a powerful method for SSR marker isolation, but it is laborious, costly, and time consuming and requires multiple rounds of washing. Here, we report a superparamagnetic bead (SPMB)-based FIASCO method in a magnetic field controllable microfluidic chip (MFCM-Chip). This method dramatically reduces the assay time by 4.25-fold and reduces the quantity of magnetic beads and probes by 10-fold through the magnetic capture of (AG)n-containing fragments from Herba Leonuri, followed by washing and eluting on a microchip. The feasibility of this method was further evaluated by PCR and sequencing, and the results showed that the proportion of fragments containing SSRs was 89%, confirming that this platform is a fast and efficient method for SSR marker isolation. This cost-effective platform will make the powerful FIASCO technique more accessible for routine use with a wide variety of materials.

Plant roots mainly consist of division, elongation and maturation regions. Histone modifications of chromatin play a vital role in plant cell growth and differentiation. However, there has been no systematic attempt to investigate the distribution patterns of histone modifications in the different plant root zones. In this study, histone H3 acetylation (H3K9ac), histone H4 acetylation (H4K5ac), and histone H3 methylation (H3K4me2, H3K4me3, H3K9me1, H3K9me2, and H3K27me2) levels and distribution patterns were examined in the root meristem, elongation and maturation zones of maize primary roots. Overall, the cells of the maturation zone displayed the highest level of multiple histone modifications. The lowest level of histone modification was detected in the root meristem. H3K9ac was enriched in the euchromatin and nucleoli of most nuclei from the elongation and maturation zones. The nucleoli of more than 60% of cells from all root regions were labeled by H4K5ac. In only a small proportion of cells (less than 7%), knobs showed H4K5ac signals. H3K4me2 and H3K4me3 were specifically detected in euchromatin. H3K9me1, H3K9me2 and H3K27me2 labeled heterochromatin and euchromatin in all the root tissues analyzed. Over 30% of elongation and maturation cells exhibited H3K9me1 signals around knobs, approximately 5% of maturation cells showed signals of H3K9me2 around knobs, and H3K27me2 was stained weakly in approximately 95% of maturation cells in knobs. Analysis of the genomic patterns of histone modifications across functionally distinct regions of maize roots reveals a root zone-specific chromatin distribution.

BACKGROUND:Salt stress usually causes crop growth inhibition and yield decrease. Epigenetic regulation is involved in plant responses to environmental stimuli. The epigenetic regulation of the cell wall related genes associated with the salt-induced cellular response is still little known. This study aimed to analyze cell morphological alterations in maize roots as a consequence of excess salinity in relation to the transcriptional and epigenetic regulation of the cell wall related protein genes. RESULTS:In this study, maize seedling roots got shorter and displayed swelling after exposure to 200 mM NaCl for 48 h and 96 h. Cytological observation showed that the growth inhibition of maize roots was due to the reduction in meristematic zone cell division activity and elongation zone cell production. The enlargement of the stele tissue and cortex cells contributed to root swelling in the elongation zone. The cell wall is thought to be the major control point for cell enlargement. Cell wall related proteins include xyloglucan endotransglucosylase (XET), expansins (EXP), and the plasma membrane proton pump (MHA). RT-PCR results displayed an up-regulation of cell wall related ZmEXPA1, ZmEXPA3, ZmEXPA5, ZmEXPB1, ZmEXPB2 and ZmXET1 genes and the down-regulation of cell wall related ZmEXPB4 and ZmMHA genes as the duration of exposure was increased. Histone acetylation is regulated by HATs, which are often correlated with gene activation. The expression of histone acetyltransferase genes ZmHATB and ZmGCN5 was increased after 200 mM NaCl treatment, accompanied by an increase in the global acetylation levels of histones H3K9 and H4K5. ChIP experiment showed that the up-regulation of the ZmEXPB2 and ZmXET1 genes was associated with the elevated H3K9 acetylation levels on the promoter regions and coding regions of these two genes. CONCLUSIONS:These data suggested that the up-regulation of some cell wall related genes mediated cell enlargement to possibly mitigate the salinity-induced ionic toxicity, and different genes had specific function in response to salt stress. Histone modification as a mediator may contribute to rapid regulation of cell wall related gene expression, which reduces the damage of excess salinity to plants.

Copper is a micronutrient required for living organisms, but is potentially toxic in excess. EDDS enhances the phytoextraction of many metals, but the underlying mechanism is fully unclear. Exposure of 200 μM Cu 2+ for 3 days resulted in rice seedling growth inhibition, accompanied by a decrease in plasma membrane H + -ATPase activity, and an increase in relative electrolyte leakage ratios, indicating that maintaining of membrane structure integrity is crucial in acclimation of plants to heavy metal stress. In addition, the chlorophyll and carotenoid content was markedly decreased and the level of the mRNA of Cytochrome P450 gene, OsHMA9 , the sulfate transporter gene, and the metallothionein-like protein gene was observed to increase in response to Cu stress. Cu treatment also induced a global epigenetic response which is associated with cell nucleus condensation. These physiological, genetic, and epigenetic responses of rice seedlings to excess copper were modified by the addition of EDDS, suggesting that the supply of EDDS in medium containing a high concentration of Cu ions could enhance plant tolerance potential to excess Cu toxicity through alleviating Cu-induced poisonous effects at various levels.

The histone modification level has been shown to be related with gene activation and repression in stress-responsive process, but there is little information on the relationship between histone modification and cell cycle gene expression responsive to environmental cues. In this study, the function of histone modifications in mediating the transcriptional regulation of cell cycle genes under various types of stress was investigated in maize (Zea mays L.). Abiotic stresses all inhibit the growth of maize seedlings, and induce total acetylation level increase compared with the control group in maize roots. The positive and negative regulation of the expression of some cell cycle genes leads to perturbation of cell cycle progression in response to abiotic stresses. Chromatin immunoprecipitation analysis reveals that dynamic histone acetylation change in the promoter region of cell cycle genes is involved in the control of gene expression in response to external stress and different cell cycle genes have their own characteristic patterns for histone acetylation. The data also showed that the combinations of hyperacetylation and hypoacetylation states of specific lysine sites on the H3 and H4 tails on the promoter regions of cell cycle genes regulate specific cell cycle gene expression under abiotic stress conditions, thus resulting in prolonged cell cycle duration and an inhibitory effect on growth and development in maize seedlings.