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Overexpression of Staphylococcus aureus efflux pumps is commonly associated with antibiotic resistance, causing conventional antibiotics to be unsuccessful in combating multidrug-resistant bacterial infections. Reducing the activity of the efflux pump is an urgently required to tackle this problem. Here, we found that plantaricin A (PlnA), an antimicrobial peptide derived from Lactobacillus plantarum, had a synergistic effect with ciprofloxacin (CIP), reducing the IC

Phosphoglucose isomerase (PGI) is a key enzyme that participates in polysaccharide synthesis, which is responsible for the interconversion of glucose-6-phosphate (G-6-P) and fructose-6-phosphate (F-6-P), but there is little research focusing on its role in fungi, especially in higher basidiomycetes. The pgi gene was cloned from Lentinula edodes and named lepgi. Then, the lepgi-silenced strains were constructed by RNA interference. In this study, we found that lepgi-silenced strains had significantly less biomass than the wild-type (WT) strain. Furthermore, the extracellular polysaccharide (EPS) and intracellular polysaccharide (IPS) levels increased 1.5- to 3-fold and 1.5-fold, respectively, in lepgi-silenced strains. Moreover, the cell wall integrity in the silenced strains was also altered, which might be due to changes in the compounds and structure of the cell wall. The results showed that compared to WT, silencing lepgi led to a significant decrease of approximately 40% in the β-1,3-glucan content, and there was a significant increase of 2-3-fold in the chitin content. These findings provide support for studying the biological functions of lepgi in L. edodes.

Nitric oxide (NO) is an important signalling molecule in stress response of organisms. We previously reported that NO decreases heat stress (HS)-induced ganoderic acid (GA) accumulation in Ganoderma lucidum. To explore the mechanisms by which NO modulates GA biosynthesis under HS, the effect of NO on the reactive oxygen species (ROS) content was examined. The results showed that NO decreased the production of mitochondrial ROS (mitROS) by 60% under HS. Further research revealed that NO reduced the mitROS content by inhibiting aconitase (Acon) activity. The GA content in Acon-silenced (Aconi) strains treated with NO donor did not differ significantly from that in untreated Aconi strains. To study the mechanism by which Acon activity is inhibited, the S-nitrosylation level of Acon was determined. Biotin-switch technology and mass spectrometry analysis were used to show that Acon is S-nitrosylated at the Cys-594 amino acid residue. Substitution of Cys-594 with a Ser, which cannot be S-nitrosylated, abolished the responsiveness of Acon to the NO-induced reduction in its enzymatic activity. These findings demonstrate that NO inhibits Acon activity through S-nitrosylation at Cys-594. In summary, these findings describe mechanism by which NO regulates GA biosynthesis via S-nitrosylation of Acon under HS condition in G. lucidum.

Cellulose is a by-product of agricultural production and an abundant waste. As a carbon source, cellulose can be degraded and utilized by fungi. Carbon sources, which act as nutrients, not only provide energy but also serve as regulators of gene expression, metabolism and growth, through various signalling networks that enable cells to sense and adapt to varying environmental conditions. Nutrient-sensing pathways prioritize the use of preferred carbon sources and regulate the production of cellulose-degrading enzymes when necessary. Understanding the regulation of the fungal cellulolytic response will become increasingly important because we strive to increase the efficiency of the utilization of these renewable energy sources. Here, we show that Glsnf1, a sucrose-nonfermenting serine-threonine-protein kinase 1 (Snf1)/AMP-activated protein kinase homologue in medicinal macro basidiomycete Ganoderma lucidum, actively responds to carbon alterations and positively regulates cellulase activity and cellulase-related gene transcription. The carbon catabolite repressor CreA, a zinc binuclear cluster transcription factor that mediates the sensing of nutrients and suppression of the transcription of a number of genes necessary for the consumption of a less preferred carbon source, participates in the Glsnf1-mediated regulation of cellulases. Glsnf1 not only negatively regulates the transcription level of the CreA gene but also hinders its localization in the nucleus. Overall, our findings reveal a key nutrient-sensing mechanism that is critical for the modulation of carbon source adaptation in G. lucidum.

How cells drive the phospholipid signal response to heat stress (HS) to maintain cellular homeostasis is a fundamental issue in biology, but the regulatory mechanism of this fundamental process is unclear. Previous quantitative analyses of lipids showed that phosphatidylinositol (PI) accumulates after HS in Ganoderma lucidum, implying the inositol phospholipid signal may be associated with HS signal transduction. Here, we found that the PI-4-kinase and PI-4-phosphate-5-kinase activities are activated and that their lipid products PI-4-phosphate and PI-4,5-bisphosphate are increased under HS. Further experimental results showed that the cytosolic Ca2+ ([Ca2+ ]c ) and ganoderic acid (GA) contents induced by HS were decreased when cells were pretreated with Li+ , an inhibitor of inositol monophosphatase, and this decrease could be rescued by PI and PI-4-phosphate. Furthermore, inhibition of PI-4-kinases resulted in a decrease in the Ca2+ and GA contents under HS that could be rescued by PI-4-phosphate but not PI. However, the decrease in the Ca2+ and GA contents by silencing of PI-4-phosphate-5-kinase could not be rescued by PI-4-phosphate. Taken together, our study reveals the essential role of the step converting PI to PI-4-phosphate and then to PI-4,5-bisphosphate in [Ca2+ ]c signalling and GA biosynthesis under HS.

Phospholipid-mediated signal transduction plays a key role in responses to environmental changes, but little is known about the role of phospholipid signalling in microorganisms. Heat stress (HS) is one of the most important environmental factors. Our previous study found that HS could induce the biosynthesis of the secondary metabolites, ganoderic acids (GA). Here, we performed a comprehensive mass spectrometry-based analysis to investigate HS-induced lipid remodelling in Ganoderma lucidum. In particular, we observed a significant accumulation of phosphatidic acid (PA) on HS. Further genetic tests in which pld-silencing strains were constructed demonstrated that the accumulation of PA is dependent on HS-activated phospholipase D (PLD) hydrolysing phosphatidylethanolamine. Furthermore, we determined the role of PLD and PA in HS-induced secondary metabolism in G. lucidum. Exogenous 1-butanol, which decreased PLD-mediated formation of PA, reverses the increased GA biosynthesis that was elicited by HS. The pld-silenced strains partly blocked HS-induced GA biosynthesis, and this block can be reversed by adding PA. Taken together, our results suggest that PLD and PA are involved in the regulation of HS-induced secondary metabolism in G. lucidum. Our findings provide key insights into how microorganisms respond to heat stress and then consequently accumulate secondary metabolites by phospholipid remodelling.

Ganoderma lucidum has become a potential model system for evaluating how environmental factors regulate the secondary metabolism of basidiomycetes. Heat stress (HS) is one of the most important environmental factors. It was previously reported that HS could induce the biosynthesis of ganoderic acids (GA). In this study, we found that HS increased GA biosynthesis and also significantly increased cell membrane fluidity. Furthermore, our results showed that addition of the membrane rigidifier dimethylsulfoxide (DMSO) could revert the increased GA biosynthesis elicited by HS. These results indicate that an increase in membrane fluidity is associated with HS-induced GA biosynthesis. Further evidence showed that the GA content was decreased in D9des-silenced strains and could be reverted to WT levels by addition of the membrane fluidizer benzyl alcohol (BA). In contrast, GA content was increased in D9des-overexpression strains and could be reverted to WT levels by the addition of DMSO. Furthermore, both membrane fluidity and GA biosynthesis induced by HS could be reverted by DMSO in WT and D9des-silenced strains. To the best of our knowledge, this is the first report demonstrating that membrane fluidity is involved in the regulation of heat stress induced secondary metabolism in filamentous fungi.

Ganoderma lucidum is one of the most important medicinal fungi, but the lack of basic study on the fungus has hindered the further development of its value. To investigate the roles of the redox system in G. lucidum, acetic acid (HAc) was applied as a reactive oxygen species (ROS) stress inducer, and hydrogen-rich water (HRW) was used to relieve the ROS stress in this study. Our results demonstrate that the treatment of 5% HRW significantly decreased the ROS content, maintained biomass and polar growth morphology of mycelium, and decreased secondary metabolism under HAc-induced oxidative stress. Furthermore, the roles of HRW were largely dependent on restoring the glutathione system under HAc stress in G. lucidum. To provide further evidence, we used two glutathione peroxidase (GPX)-defective strains, the gpxi strain, the mercaptosuccinic acid (MS, a GPX inhibitor)-treated wide-type (WT) strain, and gpx overexpression strains for further research. The results show that HRW was unable to relieve the HAc-induced ROS overproduction, decreased biomass, mycelium morphology change and increased secondary metabolism biosynthesis in the absence of GPX function. The gpx overexpression strains exhibited resistance to HAc-induced oxidative stress. Thus, we propose that HRW regulates morphology, growth and secondary metabolism via glutathione peroxidase under HAc stress in the fungus G. lucidum. Furthermore, our research also provides a method to study the ROS system in other fungi.

2D transition metal dichalcogenides are attracting increased attention because of their excellent electronic and optical properties. Inspired by the natural weathering exfoliation of seaside rocks, a “chemical weathering” concept for fabricating atom-thick 2D materials from their bulk counterparts is proposed. It is experimentally demonstrated that chemical weathering-assisted exfoliation mechanism is a simple and efficient method of preparing atom-thick MoS2 and WS2 monolayers. These monolayers are difficult to prepare using other approaches. Interestingly, the as-prepared MoS2 and WS2 monolayers exhibit excellent saturable absorption and mode-locking properties in all-solid-state lasers because of intermediate states resulting from S-vacancy defects. The obtained passively Q-switched laser operation with 60 ns pulse width and ultrafast mode locking with 8.6 ps pulse width are promising for all-solid-state laser application.

We report our first-principle's calculations on the possibility of Ca-decorated silicene sheet and zigzag silicene nanoribbons (ZSiNRs) as hydrogen storage medium. We predict that Ca atoms prefer to disperse on the silicene or at the edges of ZSiNRs without clustering, due to the strong binding between Ca and Si atoms. By adsorbing Ca atoms on the both sides of silicene, the hydrogen storage capacity can reach to 6.17 wt% (gravimetric density) with an average adsorption energy of 0.265 eV H2−1, which are quite optimial for reversible hydrogen adsorption and desorption at ambient conditions. The hydrogen storage capacity can be further improved to 8.43 wt% with the average adsorption energy in the range of 0.182–0.269 eV H2−1 in the Ca-decorated ZSiNRs. The adsorption of H2 on Ca-decorated Si nanostructures is mainly dominated by polarization and the orbital hybridizations. These findings indicate that the Ca-decorated silicene and ZSiNRs have potential application in hydrogen storage.

The bandgaps of monolayer and bulk molybdenum sulfide (MoS2 ) result in that they are far from suitable for application as a saturable absorption device. In this paper, the operation of a broadband MoS2 saturable absorber is demonstrated by the introduction of suitable defects. It is believed that the results provide some inspiration in the investigation of two-dimensional optoelectronic materials.

A novel, simple, and efficient method for the preparation of the fluorinated hexagonal boron nitride nanosheets (F-BNNSs) and the corresponding magnetic properties is presented. A one-step route is used to exfoliate and fluorinate the BNNSs by ammonium fluoride (NH4F) from hexagonal boron nitride (h-BN) powder. Through related instrument characterizations and theoretical calculations, we confirm that large-area and few-layer F-BNNSs were successfully produced by this method, which can be attributed to a fluorination-assisted exfoliation mechanism from the bulk h-BN in NH4F. More intriguingly, we initially verified that the as-prepared F-BNNSs exhibit ferromagnetic characteristics, which would have good potential applications in spintronic devices.

Many efforts have been made to develop bifunctional electrocatalysts to facilitate overall water splitting. Here, a fibrous bifunctional 3D electrocatalyst is reported for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) with high performance. The remarkable electrochemical performance is attributed of the catalysts to a number of factors: the metallic character of the three components (i.e., Ni3N, CoN, and NiCo2O4); the electronic structure, nanoflake-nanosphere network with abundant electroactive sites, and the electric field effect at the interfaces between different components. The oxide-nitride/graphite fibers have the lowest overpotential requirements of 71 and 183 mV at 10 mA cm-2 for HER and OER in alkaline medium, respectively. These values are comparable to those of commercial Pt/C (20 wt%) and RuO2. The electrodes also show a response to HER and OER in both neutral and acid media. Furthermore, the 3D structure can be highlighted by all-round electrodes for overall water splitting. The calculations on the changes in electrons transfer and the Femi level from oxides to oxides/nitrides reveal that the observed superb electrocatalytic performance can be attributed to the presence of Ni3N and CoN derived from the in situ nitridation of NiCo2O4.

Rutile titanium dioxide (TiO2 ) is a promising photocatalyst due to its high thermodynamic stability and few intragrain defects. However, it has not yet achieved photocatalytic activity comparable to that of anatase TiO2 owing to its higher recombination rate of electron-hole pairs. To effectively separate the electron-hole pairs in rutile TiO2 , a facet heterojunction (FH) structure to prolong the lifetime of the photogenerated electrons is proposed. Ultrathin TiO2 nanosheets with different facets are coated in situ onto TiO2 nanorod (NR) substrates, where FHs are built among the nanosheets as well as between the nanosheets and NR substrates. The as-prepared rutile TiO2 , with an FH structure (FH-TiO2 ), serves as an effective photocatalyst for water splitting. More than 45 and 18 times higher photogenerated current density and H2 production rate, respectively, are obtained compared to those of pure rutile TiO2 NRs. Moreover, FH-TiO2 delivers a 0.566 mmol g-1 h-1 H2 production rate even in pure water. This study offers important insights into the rational design of rutile TiO2 structures for highly efficient photocatalytic reactions. Accepted version

The novel perovskite material, SrSc0.175Nb 0.025Co0.8O3-δ, shows a rapid bulk oxygen diffusion rate below 550 °C (see oxygen movement indicated by the black arrow). Incorporation as an oxygen reduction cathode into a samarium-doped ceria fuel cell enables exceptionally high electrochemical performance, indicated by a power density of 910 mW cm-2 at 500 °C. Copyright

The photoluminescence (PL) properties of the ZnTe epilayers grown on (100) GaAs substrates with various substrate temperatures have been investigated. It has been demonstrated that the PL spectra depend strongly on the substrate temperature. A too low (390 degrees C) or too high (440 degrees C) substrate temperature deteriorates the epilayer quality due to the formation of defects or/and to the inclusion of impurities. A moderate substrate temperature (around 420 degrees C) is suitable to obtain a high-quality epilayer with the narrow spectral width and strong emission intensity. This is attributed to the moderate substrate temperature improving the crystallinity of the ZnTe epilayer by enhancing recrystallization of the adsorbed precursors. (C) 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Reports of magnetism at room temperature (RT) in pure carbon materials have stimulated studies to determine the origin of magnetism in these materials, and to explore prospective applications. The experimental evidence for ferromagnetism in proton-irradiated highly oriented pyrolytic graphite (HOPG) has provided further support of the existence of carbon magnetism. However, the origin of magnetic order in pure carbon is only poorly understood, and for many years some scientists doubted the possibility of RT ferromagnetism in these materials, which have only s and p electrons, as it was usually believed that it is only possible in materials containing metallic 3d or 4f electrons. The situation changed last year when a collaborative group of US and German scientists provided the first direct experimental evidence of p-electron ferromagnetism in metal-free carbon films by using X-ray magnetic circular dichroism (XMCD). This finding may provide a new impetus for studies of applications of magnetic carbon-based materials in diverse fields. Magnetism of carbonmaterials is of particular interest as the lightweight, cheap magnets could open up new ways to design adaptable and flexible information storage systems. The potential application of carbon-based magnets in spin electronics is promising, since carbon may provide an easy way to

We studied three possible reactions of H atom attacking the cytosine, using density functional theory (DFT) calculations. The results indicate that the H atom addition to the N3 site of cytosine is energetically more favorable than to the C5 or C6 site. The reaction of addition to the C6 site has an energy barrier of ∼2.77 kcal/mol, which is ∼2 kcal/mol higher than addition to C5. The energy of C5 H-adduct radical is also lower than that of C6 H-adduct radical. From the point of view of both energetics and reaction kinetics, the addition of the H atom to the C5 site is preferred to the addition to the C6 site. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007

We studied three possible reactions of a free ·OH radical with thymine by using density functional theory calculations. The results indicate that there is no energy barrier in the reactions of a free ·OH radical adding to the C6 position of thymine, while the reactions of a free ·OH radical adding to the C5 position of thymine and the reaction of an ·OH abstracting a hydrogen from the C5 methyl group should overcome the energy barriers of ∼0.70 kcal/mol and ∼1.88 kcal/mol, respectively. The C6-hydroxylated radical formed is energetically more favorable than the C5-hydroxylated radical. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005

Photodetectors with excellent detecting properties over a broad spectral range have advantages for the application in many optoelectronic devices. Introducing imperfections to the atomic lattices in semiconductors is a significant way for tuning the bandgap and achieving broadband response, but the imperfection may renovate their intrinsic properties far from the desire. Here, by controlling the deviation from the perfection of the atomic lattice, ultrabroadband multilayer MoS2 photodetectors are originally designed and realized with the detection range over 2000 nm from 445 nm (blue) to 2717 nm (mid-infrared). Associated with the narrow but nonzero bandgap and large photoresponsivity, the optimized deviation from the perfection of MoS2 samples is theoretically found and experimentally achieved aiming at the ultrabroadband photoresponse. By the photodetection characterization, the responsivity and detectivity of the present photodetectors are investigated in the wavelength range from 445 to 2717 nm with the maximum values of 50.7 mA W-1 and 1.55 × 109 Jones, respectively, which represent the most broadband MoS2 photodetectors. Based on the easy manipulation, low cost, large scale, and broadband photoresponse, this present detector has significant potential for the applications in optoelectronics and electronics in the future.