Chromosome-level genome of spider Pardosa pseudoannulata and cuticle protein genes in environmental stresses.

Spiders are representative arthropods of adaptive radiation. The high-quality genomes have only been reported in several web weaver spider species, leaving the wandering spiders' genomic information scarce. The pond wolf spider, Pardosa pseudoannulata, is a representative species in the retrolateral titial apophysis (RTA) clade. We present a chromosome-level P. pseusoannulata genome assembly of 2.42 Gb in size with a scaffold N50 of 169.99 Mb. Hi-C scaffolding assigns 94.83% of the bases to 15 pseudo-chromosomes. The repeats account for 52.79% of the assembly. The assembly includes 96.2% of the complete arthropod universal single-copy orthologs. Gene annotation predicted 24,530 protein-coding genes with a BUSCO score of 95.8% complete. We identified duplicate clusters of Hox genes and an expanded cuticle protein gene family with 243 genes. The expression patterns of CPR genes change in response to environmental stresses such as coldness and insecticide exposure. The high-quality P. pseudoannulata genome provides valuable information for functional and comparative studies in spiders.

Maneuvering the Peroxidase-Like Activity of Palladium-Based Nanozymes by Alloying with Oxophilic Bismuth for Biosensing.

Engineering the catalytic performance of nanozymes is of vital importance for their broad applications in biological analysis, cancer treatment, and environmental management. Herein, a strategy to boost the peroxidase-like activity of Pd-based nanozymes with oxophilic metallic bismuth (Bi) is demonstrated, which is based on the incorporation of oxophilic Bi in the Pd-based alloy nanocrystals (NCs). To synthesize PdBi alloy NCs, a seed-mediated method is employed with the assistance of underpotential deposition (UPD) of Bi on Pd. The strong interaction of Bi atoms with Pd surfaces favors the formation of alloy structures with controllable shapes and excellent monodispersity. More importantly, the PdBi NCs show excellent peroxidase-like activities compared with pristine Pd NCs. The structure-function correlations for the PdBi nanozymes are elucidated, and an indirect colorimetric method based on cascade reactions to determine alkaline phosphatase (ALP) is established. This method has good linear range, low detection limit, excellent selectivity, and anti-interference. Collectively, this work not only provides new insights for the design of high-efficiency nanozymes, expands the colorimetric sensing platform based on enzyme cascade reactions, but also represents a new example for UPD-directed synthesis of alloy NCs.

Event-Triggered Quantized Quasisynchronization of Uncertain Quaternion-Valued Chaotic Neural Networks With Time-Varying Delay for Image Encryption.

In this article, a class of quaternion-valued master-slave neural networks (NNs) with time-varying delay and parameter uncertainties was first established by conducting the extension from real-valued chaotic NNs to the quaternion field. Then, based on logarithmic quantized output feedback, the quasisynchronization issue of the NNs was investigated via devising a neoteric dynamic event-triggered controller. In virtue of the classical Lyapunov method and a generalized Halanay inequality, not only corresponding synchronization criteria were obtained to realize the quasisynchronization of master-slave NNs but also a precise upper bound was provided. Moreover, Zeno behavior can be eliminated under the presented scheme in this article. The accuracy of the theoretical outcomes was demonstrated by means of Chua's circuit. Ultimately, some experimental results of pragmatic application in image encryption/decryption were exposed to substantiate the feasibility and efficacy of the current algorithm for the proposed quaternion-valued NNs.

The impact of positive and negative information on SIR-like epidemics in delayed multiplex networks.

In order to better study the interaction between epidemic propagation and information diffusion, a new coupling model on multiplex networks with time delay is put forward in this paper. One layer represents the information diffusion about epidemics. There is not only information about the positive prevention of infectious diseases but also negative preventive information. Meanwhile, the dissemination of information at this layer will be influenced by the mass media, which can convey positive and reliable preventive measures to help the public avoid exposure to contagion. The other layer represents the transmission of infectious diseases, and the public in this layer no longer only exchange information related to infectious diseases in the virtual social network like the information layer but spread infectious diseases through contact among people. The classical SIR model is used to model for epidemic propagation. Since each infected individual needs to spend enough time to recover, the infected one at one time does not necessarily change to the recovered one at the next time, so time delay is an essential factor to be considered in the model. Based on the microscopic Markov chain approach, this paper obtains an explicit expression for epidemic threshold in the two-layered multiplex networks with time delay, which reveals some main factors affecting epidemic threshold. In particular, the time delay has a noticeable effect on the epidemic threshold to some extent. Finally, the influence of these main factors on the epidemic threshold and their interaction are proved through numerical simulations.

Time-Series Transcriptomic Analysis Reveals the Molecular Profiles of Diapause Termination Induced by Long Photoperiods and High Temperature in Chilo suppressalis.

Survival and adaptation to seasonal changes are challenging for insects. Many temperate insects such as the rice stem borer (Chilo suppressalis) overcome the adverse situation by entering diapause, wherein development changes dynamically occur and metabolic activity is suppressed. The photoperiod and temperature act as major environmental stimuli of diapause. However, the physiological and molecular mechanisms that interpret the ecologically relevant environmental cues in ontogenetic development during diapause termination are poorly understood. Here, we used genome-wide high-throughput RNA-sequencing to examine the patterns of gene expression during diapause termination in C. suppressalis. Major shifts in biological processes and pathways including metabolism, environmental information transmission, and endocrine signalling were observed across diapause termination based on over-representation analysis, short time-series expression miner, and gene set enrichment analysis. Many new pathways were identified in diapause termination including circadian rhythm, MAPK signalling, Wnt signalling, and Ras signalling, together with previously reported pathways including ecdysteroid, juvenile hormone, and insulin/insulin-like signalling. Our results show that convergent biological processes and molecular pathways of diapause termination were shared across different insect species and provided a comprehensive roadmap to better understand diapause termination in C. suppressalis.

Preferential binding of DAP-PGs by major peptidoglycan recognition proteins found in cell-free hemolymph of Manduca sexta.

Peptidoglycan recognition proteins (PGRPs) detect invading bacteria to trigger or modulate immune responses in insects. While these roles are established in Drosophila, functional studies are not yet achieved at the PGRP family level in other insects. To attain this goal, we selected Manduca sexta PGRP12 and five of the nine secreted PGRPs for recombinant expression and biochemical characterization. We cloned PGRP2-5, 12 and 13 cDNAs, produced the proteins in full (PGRP2-5, 13) or in part (PGRP3s, 12e, 13N, 13C) in Sf9 cells, and tested their bindings of two muramyl pentapeptides by surface plasmon resonance, two soluble peptidoglycans by competitive ELISA, and four insoluble peptidoglycans and eight whole bacteria by a pull-down assay. Preferential binding of meso-diaminopimelic acid-peptidoglycans (DAP-PGs) was observed in all the proteins containing a peptidoglycan binding domain and, since PGRP6, 7 and 9 proteins were hardly detected in cell-free hemolymph, the reportoire of PGRPs (including PGRP1 published previously) in M. sexta hemolymph is likely adapted to mainly detect Gram-negative bacteria and certain Gram-positive bacteria with DAP-PGs located on their surface. After incubation with plasma from naïve larvae, PGRP2, 3f, 4, 5, 13f and 13N considerably stimulated prophenoloxidase activation in the absence of a bacterial elicitor. PGRP3s and 12e had much smaller effects. Inclusion of the full-length PGRPs and their regions in the plasma also led to proHP8 activation, supporting their connections to the Toll pathway, since HP8 is a Spӓtzle-1 processing enzyme in M. sexta. Together, these findings raised concerns on the common belief that the Toll-pathway is specific for Gram-positive bacteria in insects.

Designer Gold-Framed Palladium Nanocubes for Plasmon-Enhanced Electrocatalytic Oxidation of Ethanol.

Surface plasmon of coinage metal nanostructures has been employed as a powerful route in boosting the performances in heterogenous catalysis. Development of efficient plasmonic nanocatalysts with high catalytic performance and efficient light harvesting properties is of vital importance. Herein, we rationally designed and synthesized a plasmonic nanocatalyst composed of Au-framed Pd nanocubes by an Ag(I)-assisted seed-mediated growth method. In the synthesis, the incorporation of Ag(I) suppresses the reduction of Au on the {100} surface of cubic Pd seeds and leads to the formation of Au nanoframes on the Pd nanocubes. The unique Au-framed Pd nanocubes can integrate the superior electrocatalytic of Pd and the outstanding plasmonic properties of Au. Thus, these nanostructures were employed as plasmonic nanocatalysts for plasmon-enhanced electrocatalytic oxidation of ethanol with improved stability.

Surface Molecular Functionalization of Unusual Phase Metal Nanomaterials for Highly Efficient Electrochemical Carbon Dioxide Reduction under Industry-Relevant Current Density.

The electrochemical carbon dioxide reduction reaction (CO2 RR) provides a sustainable strategy to relieve global warming and achieve carbon neutrality. However, the practical application of CO2 RR is still limited by the poor selectivity and low current density. Here, the surface molecular functionalization of unusual phase metal nanomaterials for high-performance CO2 RR under industry-relevant current density is reported. It is observed that 5-mercapto-1-methyltetrazole (MMT)-modified 4H/face-centered cubic (fcc) gold (Au) nanorods demonstrate greatly enhanced CO2 RR performance than original oleylamine (OAm)-capped 4H/fcc Au nanorods in both an H-type cell and flow cell. Significantly, MMT-modified 4H/fcc Au nanorods deliver an excellent carbon monoxide selectivity of 95.6% under the industry-relevant current density of 200 mA cm-2 . Density functional theory calculations reveal distinct electronic modulations by surface ligands, in which MMT improves while OAm suppresses the surface electroactivity of 4H/fcc Au nanorods. Furthermore, this method can be extended to various MMT derivatives and conventional fcc Au nanostructures in boosting CO2 RR performance.

Uniform Stability of Complex-Valued Neural Networks of Fractional Order With Linear Impulses and Fixed Time Delays.

As a generation of the real-valued neural network (RVNN), complex-valued neural network (CVNN) is based on the complex-valued (CV) parameters and variables. The fractional-order (FO) CVNN with linear impulses and fixed time delays is discussed. By using the sign function, the Banach fixed point theorem, and two classes of activation functions, some criteria of uniform stability for the solution and existence and uniqueness for equilibrium solution are derived. Finally, three experimental simulations are presented to illustrate the correctness and effectiveness of the obtained results.

Global Mittag-Leffler Stability of the Delayed Fractional-Coupled Reaction-Diffusion System on Networks Without Strong Connectedness.

In this article, we mainly consider the existence of solutions and global Mittag-Leffler stability of delayed fractional-order coupled reaction-diffusion neural networks without strong connectedness. Using the Leary-Schauder's fixed point theorem and the Lyapunov method, some criteria for the existence of solutions and global Mittag-Leffler stability are given. Finally, the correctness of the theory is verified by a numerical example.

Unveiling the Actual Catalytic Sites in Nanozyme-Catalyzed Oxidation of o-Phenylenediamine.

Nanozymes have offered remarkable advantages over natural enzymes and found widespread applications including biosensors, immunoassays, nanomedicines, and environmental remediation. Oxidation of o-phenylenediamine (OPD) by nanozymes has been listed as a standard protocol for determining nanozyme activities. Given the complexity of OPD oxidation processes, however, the mechanism of nanozyme-catalyzed oxidation of OPD remains elusive. In this report, mechanistic studies of nanozyme-catalyzed oxidation of OPD are performed and a distinguishably different mechanism from that of natural enzymes is found. A combination of Fourier transform infrared spectroscopy, nuclear magnetic resonance, electrospray ionization mass spectrometry, and electron microscopic studies provides compelling evidence that polymerization of OPD occurs on the surface of several different nanozymes. The unexpected polymerization causes a dense coating layer of poly(o-phenylenediamine) (POPD) on nanozymes renders the intrinsic properties of nanozymes. Therefore, this fundamental discovery raise serious concerns using OPD-based colorimetric method for determining nanozyme activities. Without examining the surface change of nanozymes after catalytic reactions, the use of OPD-based colorimetric method for determining nanozyme activities is strongly discouraged. Furthermore, POPD is discovered as a new oxidase mimic, and this new mechanism also provides a general and robust method to coat nanomaterials with POPD polymers of enzyme-mimicking properties.

Neonicotinoids stimulate H2-limited methane emission in Periplaneta americana through the regulation of gut bacterium community.

Methane emitted by insects is considered to be an important source of atmospheric methane. Here we report the stimulation of methane emission in the cockroach Periplaneta americana and termite Coptotermes chaohuensis, insects with abundant methanogens, by neonicotinoids, insecticides widely used to control insect pests. Cycloxaprid (CYC) and imidacloprid (IMI) caused foregut expansion in P. americana, and increased the methane emission. Antibiotics mostly eliminated the effects. In P. americana guts, hydrogen levels increased and pH values decreased, which could be significantly explained by the gut bacterium community change. The proportion of several bacterium genera increased in guts following CYC treatment, and two genera from four could generate hydrogen. Hydrogen is a central intermediate in methanogenesis. All increased methanogens in both foregut and hindgut used hydrogen as electron donor to produce methane. Besides, the up-regulation of mcrA, encoding the enzyme for the final step of methanogenesis suggested the enhanced methane production ability in present methanogens. In the termite, hydrogen levels in gut and methane emission also significantly increased after neonicotinoid treatment, which was similar to the results in P. americana. In summary, neonicotinoids changed bacterium community in P. americana gut to generate more hydrogen, which then stimulated gut methanogens to produce and emit more methane. The finding raised a new concern over neonicotinoid applications, and might be a potential environmental risk associated with atmospheric methane.

Surface engineering of Rh-modified Pd nanocrystals by colloidal underpotential deposition for electrocatalytic methanol oxidation.

The development of methods to control the surface structures of metallic nanocatalysts is of vital importance for their application as heterogeneous catalysts in chemical conversions of energy and environmental and chemical engineering. The underpotential deposition (UPD) phenomenon has received considerable interest as a tool for the controllable synthesis of metal nanocrystals and engineering their catalytic performances. Herein, the discovery of UPD of Rh on Pd nanocrystals is reported. More importantly, the UPD of Rh is explored as a strategy to direct the synthesis of Rh-modified Pd nanocrystals with controllable shapes and surface structures. The mechanism of the UPD of Rh on Pd is elucidated in terms of electronegativity difference considerations. Compared with pristine Pd octahedral nanocrystals and commercial carbon-supported Pd catalysts, the Rh-modified Pd octahedral nanocrystals exhibit remarkable electrocatalytic performances during the methanol oxidation reaction in alkaline media. Our discovery heralds a new paradigm for UPD-mediated growth of metal nanocrystals and may provide a mechanistic understanding for the guided design of other colloidal UPD systems in the synthesis and surface engineering of metal nanocrystals.

Adaptive Synchronization of Fractional-Order Output-Coupling Neural Networks via Quantized Output Control.

This article focuses on the adaptive synchronization for a class of fractional-order coupled neural networks (FCNNs) with output coupling. The model is new for output coupling item in the FCNNs that treat FCNNs with state coupling as its particular case. Novel adaptive output controllers with logarithm quantization are designed to cope with the stability of the fractional-order error systems for the first attempt, which is also an effective way to synchronize fractional-order complex networks. Based on fractional-order Lyapunov functionals and linear matrix inequalities (LMIs) method, sufficient conditions rather than algebraic conditions are built to realize the synchronization of FCNNs with output coupling. A numerical simulation is put forward to substantiate the applicability of our results.

Dual roles of underpotential deposition in the synthesis of tetrahexahedral Pd-Ag alloy nanocrystals.

Tetrahexahedral Pd-Ag alloy nanocrystals enclosed by high-index {520} facets with enhanced electrocatalytic activity have been synthesized using an Ag(i)-assisted growth protocol. The underpotential deposition of Ag plays dual roles in the formation of tetrahexahedral nanocrystals: it not only stabilizes the high-index {520} facets, but also facilitates the formation of Pd-Ag alloys.

Synchronization criteria for quaternion-valued coupled neural networks with impulses.

We consider the global exponential synchronization of a category of quaternion-valued coupled neural networks (QVCNNs) with impulses in this article. It makes up for the gap of coupled neural networks with impulses in quaternion. On account of the product of two quaternions cannot be exchanged under normal circumstances, for convenience, we isolate the QVCNN into four real-valued coupled neural networks (RVCNNs) which are converted into an augmented system by defining a new augmented vector. By leveraging a distinctive Lyapunov-Krasovskii function and some matrix inequalities, several sufficient conditions for the global exponential synchronization of the system are attained. Ultimately, two examples are used to prove the validity of the theories in this paper.

Non-fragile state estimation for fractional-order delayed memristive BAM neural networks.

This paper deals with the non-fragile state estimation problem for a class of fractional-order memristive BAM neural networks (FMBAMNNs) with and without time delays for the first time. By means of a novel transformation and interval matrix approach, non-fragile estimators are designed and parameter mismatch problem is averted. Sufficient criteria are established to ascertain the error system is asymptotically stable based on fractional-order Lyapunov functionals and linear matrix inequalities (LMIs). Two examples are put forward to show the effectiveness of the obtained results.

Niemann-Pick proteins type C2 are identified as olfactory related genes of Pardosa pseudoannulata by transcriptome and expression profile analysis.

In arthropods, the large majority of studies on olfaction have been mainly focused on insects, whereas little on Arachnida, even though olfaction is very important in arachnid behavior. Pardosa pseudoannulata is one of the most common wandering spiders in rice fields, as the important natural enemy against a range of pests. However, little is known about the potential chemosensory proteins involved in olfactory behavior of these spiders. Niemann-Pick proteins type C2 (NPC2) as a new class of binding and transport proteins for semiochemicals in arthropods especially ticks and mites has received more attention in recent years. In this study, six NPC2s namely PpseNPC1-6 were newly identified in the appendages of P. pseudoannulata based on transcriptome data. A phylogenetic analysis indicated that all of P. pseudoannulata NPC2s were clustered together forming one clade with high posterior probability values. In addition, the sequences shared the same subclade with the NPC2 sequences of ticks and scorpion. The motif-patterns indicated that PpseNPC2-5 had the common pattern with the two-spotted spider mite Tetranychus urticae and the ant Trachymyrmex cornetzi. Furthermore, quantitative real-time PCR (qPCR) measurements were conducted to evaluate the expression profile of these genes in various tissues of P. pseudoannulata. It was found that most NPC2s (PpseNPC2-1, PpseNPC2-2, PpseNPC2-5 and PpseNPC2-6) were highly expressed in adult pedipalps and chelicerae. Owing to the functional olfactory organs in Chelicerata of pedipalps, our results supported a putative role of NPC2s as new odorant carriers in P. pseudoannulata.

Identification and functional study of three nAChR regulators, ubiquilin-1, PICK1, and CRELD2, in Locusta migratoria manilensis dorsal unpaired median neurons.

Insect nicotinic acetylcholine receptors (nAChRs) are not only important neurotransmitter receptors but also effective insecticide targets. The regulation of nAChRs has been mainly studied in vertebrates, especially in mammals. Here, two types of nAChRs were found present in the locust Locusta migratoria manilensis dorsal unpaired median (DUM) neurons, α-bungarotoxin (α-Bgt)-sensitive nAChRs and α-Bgt-resistant nAChRs, responding to acetylcholine (ACh) at different concentrations. The homologs to three mammalian nAChR regulators, ubiquilin-1, CRELD2 (cysteine-rich with EFG-like domain 2), and PICK1 (protein interacting with PRKCA 1), were characterized in L. migratoria, and their functions on regulating native nAChRs were investigated via RNAi followed by membrane potential measurement with DiBAC4 (3) and agonist-evoked macroscopic current recording in cultured L. migratoria DUM neurons. Ubiquilin-1 and PICK1 negatively regulated nAChRs because silencing of ubiquilin-1 and PICK1 both resulted in increased membrane potential and increased inward currents in DUM neurons, while CRELD2 positively regulated nAChRs as decreased membrane potential and inward currents were observed in DUM neurons. In addition, ubiquilin-1 regulated both α-Bgt-sensitive and α-Bgt-resistant types of nAChRs whereas PICK1 and CRELD2 regulated only the α-Bgt-resistant nAChRs. The present study broadened our understanding on the regulation of insect nAChRs and will benefit pest management given the important role of nAChRs in insect neurons and insecticide science. OPEN SCIENCE BADGES: This article has received a badge for *Open Materials* because it provided all relevant information to reproduce the study in the manuscript. The complete Open Science Disclosure form for this article can be found at the end of the article. More information about the Open Practices badges can be found at https://cos.io/our-services/open-science-badges/.

The binding properties of cycloxaprid on insect native nAChRs partially explain the low cross-resistance with imidacloprid in Nilaparvata lugens.

BACKGROUND: Neonicotinoids, such as imidacloprid, are selective agonists of insect nicotinic acetylcholine receptors (nAChRs) used to control Nilaparvata lugens, a major rice insect pest. High imidacloprid resistance has been reported in N. lugens both in the laboratory and in the field. Cycloxaprid (CYC), an oxa-bridged cis-nitromethylene neonicotinoid, showed high insecticidal activity against N. lugens and low cross-resistance in imidacloprid-resistant strains and field populations. RESULTS: Binding studies demonstrated that imidacloprid has two binding sites with different affinities (Kd = 3.18 ± 0.43 pm and 1.78 ± 0.19 nm) in N. lugens nAChRs. CYC was poor at displacing [3 H]imidacloprid at its high-affinity binding site (Ki = 159.38 ± 20.43 nm), but quite efficient at the low-affinity binding site (Ki = 1.27 ± 0.35 nm). These data showed that CYC had overlapping binding sites with imidacloprid only at its low-affinity binding site. Therefore, the low displacement ability of CYC against imidacloprid binding at its high-affinity site could partially explain the low cross-resistance of CYC in imidacloprid-resistant populations. CONCLUSION: The high insecticidal activity, low cross-resistance and different binding properties on insect nAChRs of CYC show that it is a potential insecticide for the control of N. lugens and related insect pests, especially ones with high resistance to neonicotinoids. © 2018 Society of Chemical Industry.