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Although microRNA408 (miR408) is a highly conserved miRNA, the miR408 response to salt stress differs among plant species. Here, we show that miR408 transcripts are strongly repressed by salt stress and methyl viologen treatment in maize (Zea mays). Application of N, N1-dimethylthiourea partly relieved the NaCl-induced down-regulation of miR408. Transgenic maize overexpressing MIR408b is hypersensitive to salt stress. Overexpression of MIR408b enhanced the rate of net Na+ efflux, caused Na+ to locate in the inter-cellular space, reduced lignin accumulation, and reduced the number of cells in vascular bundles under salt stress. We further demonstrated that miR408 targets ZmLACCASE9 (ZmLAC9). Knockout of MIR408a or MIR408b or overexpression of ZmLAC9 increased the accumulation of lignin, thickened the walls of pavement cells, and improved salt tolerance of maize. Transcriptome profiles of the wild-type and MIR408b-overexpressing transgenic maize with or without salt stress indicated that miR408 negatively regulates the expression of cell wall biogenesis genes under salt conditions. These results indicate that miR408 negatively regulates salt tolerance by regulating secondary cell wall development in maize.

Patulin is a fatal mycotoxin that is widely detected in drinking water and fruit-derived products contaminated by diverse filamentous fungi. CgSDR from Candida guilliermondii represents the first NADPH-dependent short-chain dehydrogenase/reductase that catalyzes the reduction of patulin to the nontoxic E-ascladiol. To elucidate the catalytic mechanism of CgSDR, we solved its crystal structure in complex with cofactor and substrate. Structural analyses indicate that patulin is situated in a hydrophobic pocket adjacent to the cofactor, with the hemiacetal ring orienting toward the nicotinamide moiety of NADPH. In addition, we conducted structure-guided engineering to modify substrate-binding residue V187 and obtained variant V187F, V187K and V187W, whose catalytic activity was elevated by 3.9-, 2.2- and 1.7-fold, respectively. The crystal structures of CgSDR variants suggest that introducing additional aromatic stacking or hydrogen-bonding interactions to bind the lactone ring of patulin might account for the observed enhanced activity. These results illustrate the catalytic mechanism of SDR-mediated patulin detoxification for the first time and provide the upgraded variants that exhibit tremendous potentials in industrial applications.

We propose a technique, based on the natural gradient method, for variational lower bound maximization for a variational Bayesian Kalman filter. The natural gradient approach is applied to the Kullback-Leibler divergence between the parameterized variational distribution and the posterior density of interest. Using a Gaussian assumption for the parametrized variational distribution, we obtain a closed-form iterative procedure for the Kullback-Leibler divergence minimization, producing estimates of the variational hyper-parameters of state estimation and the associated error covariance. Simulation results in both a Doppler radar tracking scenario and a bearing-only tracking scenario are presented showing that the proposed natural gradient method outperforms existing methods which are based on other linearization techniques in terms of tracking accuracy.

Lodging is a major problem limiting maize yield worldwide. However, the mechanisms of lodging resistance remain incompletely understood for maize. Here, we evaluated 443 maize accessions for lodging resistance in the field. Five lodging-resistant accessions and five lodging-sensitive accessions were selected for further research. The leaf number, plant height, stem diameter, and rind penetrometer resistance were similar between lodging-resistant and -sensitive inbred lines. The average thickness of sclerenchymatous hypodermis layer was thicker and the vascular area was larger in the lodging-resistant lines compared with lodging-sensitive lines. Although total lignin content in stem tissue did not significantly differ between lodging-resistant and -sensitive lines, phloroglucinol staining revealed that the lignin content of the cell wall in the stem cortex and in the stem vascular tissue near the cortex was higher in the lodging-resistant lines than in the lodging-sensitive lines. Analysis of strand-specific RNA-seq transcriptome showed that a total of 793 genes were up-regulated and 713 genes were down-regulated in lodging-resistant lines relative to lodging-sensitive lines. The up-regulated genes in lodging-resistant lines were enriched in cell wall biogenesis. These results indicated that modification of cell wall biosynthesis would contribute to lodging resistance of maize.

The nonlinearity of bending stiffness caused by inter-wire slippage has become the major challenge in the prediction of strand bending behavior. This paper proposed an analytical approach to predict the hysteretic bending behavior of helical strands. As an extension of classical models, this paper additionally considered the wire slippage delayed by bending load. Moreover, the method of integral for discrete contact regions extended the always assumed continuous contact region into the discontinuous, which enables this model to analyze the realistic conditions of multi-layered strands having alternating algebraic signs of lay angles, such as ACSR conductors and S32 cable. The present model is compared with FEM and experimental data, and results demonstrated the effectiveness of this model in strand bending prediction.

Nonheme iron- and α-ketoglutarate (αKG)-dependent halogenases (NHFeHals), which catalyze the regio- and stereoselective halogenation of the unactivated C(sp(3))-H bonds, exhibit tremendous potential in the challenging asymmetric halogenation. AdeV from Actinomadura sp. ATCC 39365 is the first identified carrier protein-free NHFeHal that catalyzes the chlorination of nucleotide 2′-deoxyadenosine-5′-monophosphate (2′-dAMP) to afford 2′-chloro-2′-deoxyadenosine-5′-monophosphate. Here, we determined the complex crystal structures of AdeV/Fe(II)/Cl and AdeV/Fe(II)/Cl/αKG at resolutions of 1.76 and 1.74 Å, respectively. AdeV possesses a typical β-sandwich topology with H194, H252, αKG, chloride, and one water molecule coordinating Fe(II) in the active site. Molecular docking, mutagenesis, and biochemical analyses reveal that the hydrophobic interactions and hydrogen bond network between the substrate-binding pocket and the adenine, deoxyribose, and phosphate moieties of 2′-dAMP are essential for substrate recognition. Residues H111, R177, and H192 might play important roles in the second-sphere interactions that control reaction partitioning. This study provides valuable insights into the catalytic selectivity of AdeV and will facilitate the rational engineering of AdeV and other NHFeHals for synthesis of halogenated nucleotides. IMPORTANCE Halogenated nucleotides are a group of important antibiotics and are clinically used as antiviral and anticancer drugs. AdeV is the first carrier protein-independent nonheme iron- and α-ketoglutarate (αKG)-dependent halogenase (NHFeHal) that can selectively halogenate nucleotides and exhibits restricted substrate specificity toward several 2′-dAMP analogues. Here, we determined the complex crystal structures of AdeV/Fe(II)/Cl and AdeV/Fe(II)/Cl/αKG. Molecular docking, mutagenesis, and biochemical analyses provide important insights into the catalytic selectivity of AdeV. This study will facilitate the rational engineering of AdeV and other carrier protein-independent NHFeHals for synthesis of halogenated nucleotides.

An arc-coloured digraph is rainbow antistrong connected if any two distinct vertices u, v are connected by both a forward antidirected (u, v)-trail and a forward antidirected (v, u)-trail which do not use two arcs with the same colour. The rainbow antistrong connection number of a digraph D is the minimum number of colours needed to make the digraph rainbow antistrong connected, denoted by $$\overset{\rightarrow }{rac}(D)$$ . An arc-coloured digraph is strong rainbow antistrong connected if any two distinct vertices u, v are connected by both a forward antidirected (u, v)-geodesic trail and a forward antidirected (v, u)-geodesic trail which do not use two arcs with the same colour. The strong rainbow antistrong connection number of a digraph D, denoted by $$\overset{\rightarrow }{srac}(D)$$ , is the minimum number of colours needed to make the digraph strong rainbow antistrong connected. In this paper, we prove that for any antistrong tournament $$T_n$$ with n vertices $$\overset{\rightarrow }{rac}(T_n)\ge 3$$ and $$\overset{\rightarrow }{srac}(T_n)\ge 3$$ , and we construct tournaments $$T_n$$ with $$\overset{\rightarrow }{rac}(T_n)=\overset{\rightarrow }{srac}(T_n)=3$$ for every $$n\ge 18$$ . Then, we prove that for any antistrong tournament $$T_n$$ whose diameter is at least 4, $$\overset{\rightarrow }{rac}(T_n)\le 7$$ , and we construct tournaments $$T_n$$ whose diameter is 3 with $$\overset{\rightarrow }{rac}(T_n)=7$$ for every $$n\ge 5$$ .

MicroRNAs (miRNAs/miRs) have been reported to affect ischemia/reperfusion (I/R)-induced cerebral damage. miRNAs cause post-transcriptional gene silencing by binding to the protein-coding sequence (CDS) of mRNAs. Seipin has a potential role in regulating autophagic flux. The present study investigated the involvement of miR-187-3p in Seipin expression, autophagic flux and apoptosis in vitro, as well as the underlying mechanism, using PC12 cells exposed to oxygen-glucose deprivation/reoxygenation (OGD/R), which mimicked the process of I/R. In comparison with control PC12 cells, OGD/R caused an increase in the level of miR-187-3p and a decrease in Seipin protein levels without changes in the level of Seipin mRNA. Using bioinformatics analysis, it was identified that miR-187-3p could bind to the CDS of Seipin. miR-187-3p inhibitor attenuated the reduction in Seipin protein expression in OGD/R-treated PC12 cells. Following OGD/R, autophagic flux was reduced and apoptosis was enhanced, which were attenuated by inhibition of miR-187-3p. Compared with OGD/R-treated PC12 cells, Seipin knockdown further impaired autophagic flux and promoted neuronal apoptosis, which were insensitive to inhibition of miR-187-3p. Furthermore, treatment with miR-187-3p inhibitor could decrease the infarction volume in a rat model of middle cerebral artery occlusion/reperfusion. The present findings indicated that miR-187-3p inhibitor attenuated ischemia-induced cerebral damage by rescuing Seipin expression to improve autophagic flux.

Alzheimer's disease (AD) is a chronic and irreversible neurodegenerative disorder. Abnormal aggregation of the neurotoxic amyloid‑β (Aβ) peptide is an early event in AD. The activation of astrocytic α7 nicotinic acetylcholine receptor (α7 nAChR) can inhibit Aβ aggregation; thus, the molecular mechanism between α7 nAChR activation and Aβ aggregation warrants further investigation. In the present study, Aβ oligomer levels were assessed in astrocytic cell lysates after treatment with PNU282987 (a potent agonist of α7 nAChRs) or co‑treatment with LY294002, a p‑Akt inhibitor. The levels of heat shock factor‑1 (HSF‑1), heat shock protein 70 (HSP‑70), and αB‑crystallin (Cryab) in astrocytes treated with PNU282987 at various time‑points or co‑treated with methyllycaconitine (MLA), a selective α7 nAChR antagonist, as well as co‑incubated with LY294002 were determined by western blotting. HSP‑70 and Cryab levels were determined after HSF‑1 knockdown (KD) in astrocytes. PNU282987 markedly inhibited Aβ aggregation and upregulated HSF‑1, Cryab, and HSP‑70 in primary astrocytes, while the PNU282987‑mediated neuroprotective effect was reversed by pre‑treatment with MLA or LY294002. Moreover, the HSF‑1 KD in astrocytes effectively decreased Cryab, but not HSP‑70 expression. HSF‑1 is necessary for the upregulation of Cryab expression, but not for that of HSP‑70. HSF‑1 and HSP‑70 have a neuroprotective effect. Furthermore, the neuroprotective effect of PNU282987 against Aβ aggregation was mediated by the canonical PI3K/Akt signaling pathway activation.

A time-varying sensor delay is inevitable in a mining cable elevator operating at a maximum distance which is more than 2000-m underground, when the sensor signals are transmitted from a cage at the bottom of the cable to a control center on the ground through a set of wireless devices, including emitters and receivers. This sensor delay may degrade the estimation precision of the state observer or even destroy the stability of the closed-loop system. In this brief, we design an observer which can compensate the sensor delay with a time-varying and arbitrary length to estimate the vibration states of the mining cable elevator, including the time-varying-length mining cable and the cage. The vibration dynamics of the mining cable elevator is described by a wave partial differential equation (PDE)-ordinary differential equation (ODE) coupled system on a time-varying domain, and the sensor delay dynamics is represented by a transport PDE on a time-varying domain. A full-order infinite dimensional observer is constructed to estimate the states of such a wave PDE-ODE-transport PDE coupled system where PDEs are on time-varying domains, only using available boundary values without measurements at the connection points of the PDEs and ODE. The exponential stability of the observer error system is proved via Lyapunov analysis. The effectiveness of the proposed observer is verified via numerical simulation.

Background To determine the role of HOXD10 in pancreatic cancer. Methods A stable HOXD10-expressing PANC-1 cell line was established. Proliferation rates were detected by 5-Ethynyl-2'-deoxyuridine (Edu) staining while invasion was evaluated by Transwell assay. The expression levels of different proteins were analyzed by Western blotting. A subcutaneous xenograft of pancreatic cancer was established in nude mice, and the tumor weight and body weight were monitored. The in-situ expression of relevant markers in the tumor tissues was detected by immunohistochemistry. Results HOXD10 overexpression significantly decreased the proliferation rates of PANC-1 cells, and down-regulated Ki67 and Survivin (P

This paper investigates the fracture process featured wide triaxiality range (− 0.1, 2/3), with varied fracture mode observed by fractography. The micro fracture mode changes from shear fracture in low triaxiality to dimple rupture in high triaxiality. The fracture locus (fracture strain vs. triaxiality) exhibits complex trends, containing increased fracture strain in negative triaxiality. Hardening behavior is calculated by classic J2 flow theory and the Ludwig hardening law. Coupling process of softening and fracture are represented by the GISSMO model. The deforming and the coupling process are solved by 2D and 3D finite element method by LS-Dyna/Explicit. Good agreements are observed between experimental and numerical results in tensile tests, punch tests and three points bending tests, verifying that the GISSMO model and Ludwig hardening law can be used in deforming and fracture process for 7003 alloy. Numerical predictions on perforated beam bending shows that the opening can change the cracking position, increases the ultimate strength and decreases the deflection.

The Tur?n number ex(n,H) of a graph H, is the maximum number of edges in a graph of order n which does not contain H as a subgraph. Let Ex(n,H) denote all H-free graphs on n vertices with ex(n,H) edges. Let Pi denote a path consisting of i vertices, and mPi denote m disjoint copies of Pi. In this paper, we give the Tur?n number ex(n,3P5) for all positive integers n, which partly solve the conjecture proposed by L. Yuan and X. Zhang [7]. Moreover, we characterize all extremal graphs of 3P5 denoted by Ex(n, 3P5).

Designing a good engine accessory drive system becomes a hard work with its increasingly complicated configuration and high demands on its dynamic characteristics. In this work, a hybrid mutation particle swarm optimization (HMPSO) algorithm is presented to optimize the key structure parameters of an engine accessory drive system for its vibration control. The superiority of the HMPSO algorithm against several other concerned metaheuristic algorithms in terms of solution quality and stability are verified by non-parametric statistical tests on ten benchmark functions. The design problem of the engine accessory drive system is a multi-objective optimization problem; the weighted sum method and main target method are applied to convert it to a single-objective one. Optimization on an example engine accessory drive system using the HMPSO algorithm demonstrates obvious improvement in system vibration after optimization. A robustness analysis is conducted to identify the robustness of dynamic responses of the engine accessory drive system with respect to small variations of the design variables relative to the optimal design in the design space, and suggestions on design of an engine accessory drive system are given according to it.

Plant root architecture flexibly adapts to changing nitrate (NO

Deoxynivalenol (DON) and its acetylated derivatives such as 3-acetyldeoxynivalenol (3A-DON) and 15-acetyldeoxynivalenol (15A-DON) are notorious mycotoxins in Fusarium contaminated cereals, which pose a great threat to human and livestock health. The specialized glyoxalase I from Gossypium hirsutum (SPG) can lower the toxicity of 3A-DON by conducting isomerization to transfer C8 carbonyl to C7 and double bond from C9-C10 to C8-C9. Here we report that the substrate-flexible SPG can also recognize 15A-DON and DON, probably following the same isomerization mechanism as that for 3A-DON. The crystallographic, mutagenesis, and biochemical analyses revealed that SPG provides a hydrophobic pocket to accommodate the substrate and residue E167 might serve as the catalytic base. A variant SPG

The massive accumulation of polyethylene terephthalate (PET) in the global ecosystem is a growing environmental crisis. Development of environmental friendly strategies to achieve enzyme–catalyzed PET degradation has attracted tremendous attention. In this study, we demonstrated the synergistic effects of combining a specific PET–degrading enzyme IsPETaseEHA variant from PET–assimilating bacterium Ideonella sakaiensis and a lytic polysaccharide monooxygenase from a white–rot fungus Pycnoporus coccineus (PcAA14A) in PET degradation. We found that the presence of PcAA14A alone did not result in PET hydrolysis, but its presence could stimulate IsPETaseEHA–mediated hydrolytic efficiency by up to 1.3-fold. Notably, the stimulatory effects of PcAA14A on IsPETaseEHA–catalyzed PET hydrolysis were found to be independent of monooxygenase activity. Dose–effects of IsPETaseEHA and PcAA14A on PET hydrolysis were observed, with the optimal concentrations being determined to 25 μg/mL and 0.25 μg/mL, respectively. In the 5-day PET hydrolysis experiment, 1097 μM hydrolysis products were produced by adding the optimized concentrations of IsPETaseEHA and PcAA14A, which was 27.7% higher than those were produced by IsPETaseEHA alone. Our study reports the first time that PcAA14A could stimulate the IsPETaseEHA–mediated PET hydrolysis through a monooxygenase activity independent manner.

Background Alanine and proline-rich protein (Apa) is a secreted antigen of Mycobacterium spp. which involves in stimulating immune responses and adhering to host cells by binding to fibronectin (Fn). Here, we report the crystal structure of Apa from Mycobacterium tuberculosis (Mtb) and its Fn-binding characteristics. Methods The crystal structure of Mtb Apa was determined at resolutions of 1.54 A. The dissociation constants (KD) of Apa and individual modules of Fn were determined by surface plasmon resonance and enzyme-linked immunosorbent assay. Site-directed mutagenesis was performed to investigate the putative Fn-binding motif of Apa. Results Mtb Apa folds into a large seven-stranded anti-parallel β-sheet which is flanked by three α-helices. The binding affinity of Mtb Apa to individual Fn modules was assessed and the results indicated that the Mtb Apa binds to FnIII-4 and FnIII-5 of Fn CBD segment. Notably, structure analysis suggested that the previously proposed Fn-binding motif 258RWFV261 is buried within the protein and may not be accessible to the binding counterpart. Conclusions The structural and Fn-binding characteristics we reported here provide molecular insights into the multifunctional protein Mtb Apa. FnIII-4 and FnIII-5 of CBD are the only two modules contributing to Apa-Fn interaction. General significance This is the first study to report the structure and Fn-binding characteristics of mycobacterial Apa. Since Apa plays a central role in stimulating immune responses and host cells adhesion, these results are of great importance in understanding the pathogenesis of mycobacterium. This information shall provide a guidance for the development of anti-mycobacteria regimen.

Moenomycin-type antibiotics are phosphoglycolipids that are notable for their unique modes of action and have proven to be useful in animal nutrition. The gene clusters tchm from Actinoplanes teichomyceticus and moe from Streptomyces are among a limited number of known moenomycin-biosynthetic pathways. Most genes in tchm have counterparts in the moe cluster, except for tchmy and tchmz, the functions of which remain unknown. Sequence analysis indicates that TchmY belongs to the isoprenoid enzyme C2-like superfamily and may serve as a prenylcyclase. The enzyme was proposed to be involved in terminal cyclization of the moenocinyl chain in teichomycin, leading to the diumycinol chain of moenomycin isomers. Here, recombinant TchmY protein was expressed in Escherichia coli and its crystal structure was solved by SIRAS. Structural analysis and comparison with other prenylcyclases were performed. The overall fold of TchmY consists of an (α/α)6-barrel, and a potential substrate-binding pocket is found in the central chamber. These results should provide important information regarding the biosynthetic basis of moenomycin antibiotics.

Hydroalkoxylation is a useful and efficient reaction which generates C-O bond and produces cyclic ethers, the common structural elements of natural products. The dedicative enzyme which can catalyze enantioselective hydroalkoxylation named PhnH was recently identified in the herqueinone biosynthetic gene from Penicillium herquei. It catalyzes addition of a phenol to the terminal olefin on substrate to produce a dihydrobenzofuran. Here, the crystal structure of PhnH is reported and the putative substrate-binding pocket is illustrated. Through docking experiment, possible substrate-binding poses are displayed and the catalytic mechanism is therefore proposed. Our findings form the basis for further studies of enantioselective hydroalkoxylation enzymes.

Precise forecasts of road surface temperature (RST) and road conditions allow winter roads to be maintained efficiently. The upcoming “big data” application known as “floating car data” (FCD) provides the opportunity to improve road weather forecasts with measurements of air temperature Ta from in-car sensors. The research thus far with regard to thermal mapping has mainly focused on clear and calm nights, which occur rarely and during low traffic intensity. It is expected that more than 99% of the FCD will be collected during conditions other than clear and calm nights. Utilizing 32 runs of thermal mapping and controlled Ta surveys carried out on mostly busy roads over one winter season, it was possible to simulate the use of Ta and geographical parameters to reflect the variation of RST. The results show that the examined route had several repeatable thermal fingerprints during times of relatively high traffic intensity and with different weather patterns. The measurement time, real-time weather pattern, and previous weather patterns influenced the spatial pattern of thermal fingerprints. The influence of urban density and altitude on RST can be partly seen in their relationship with Ta, whereas the influence of shading and sky-view factor was only seen for RST. The regression models with Ta included explained up to 82% of the RST distribution and outperformed models that are based only on the geographical parameters by as much as 30%. The performance of the models denotes the possible utility of Ta from FCD, but further investigation is needed before moving from controlled Ta measurements to Ta from FCD.