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[This corrects the article DOI: 10.1371/journal.pone.0298338.].

In this study, the resistive switching scheme using TiO 2 nanorod arrays synthesized by a large-scale and low-cost hydrothermal process was reported. Especially, the nonlinear I–V characteristics of TiO 2 nanorod arrays with a nonlinearity of up to ~10, which suppress the leakage current less than 10 −4  Acm −2 , were demonstrated, exhibiting a self-selecting resistive switching behavior. It provides a simple pathway for integration of RRAM crossbar arrays without additional stacking of active devices. The mechanisms of the nonlinear resistive switching behaviors were discussed in detail. In addition, the maximum array numbers of 79 for self-selecting RRAM cells were estimated. The results demonstrate an opportunity of using the concept of self-selecting resistive switching characteristics in a single material, which offers a new strategy to tackle the sneak path issue of RRAM in the crossbar arrays structure.

The black soldier fly (BSF), Hermetia illucen s, has the potential to serve as a valuable resource for waste bioconversion due to the ability of the larvae to thrive in a microbial-rich environment. Being an ecological decomposer, the survival of BSF larvae (BSFL) relies on developing an efficient defense system. Cathepsin L (CTSL) is a cysteine protease that plays roles in physiological and pathological processes. In this study, the full-length of CTSL was obtained from BSF. The 1,020-bp open reading frame encoded a preprotein of 339 amino acids with a predicted molecular weight of 32 kDa. The pro-domain contained the conserved ERFNIN, GNYD, and GCNGG motifs, which are all characteristic of CTSL. Homology revealed that the deduced amino acid sequence of BSF CTSL shared 74.22–72.99% identity with Diptera flies. Immunohistochemical (IHC) analysis showed the CTSL was predominantly localized in the gut, especially in the midgut. The mRNA expression of CTSL in different larval stages was analyzed by quantitative real-time PCR (RT-qPCR), which revealed that CTSL was expressed in the second to sixth instar, with the highest expression in the fifth instar. Following an immune challenge in vivo using Escherichia coli ( E . coli ), CTSL mRNA was significantly up-regulated at 6 h post-stimulation. The Z-Phe-Arg-AMC was gradually cleaved by the BSFL extract after 3 h post-stimulation. These results shed light on the potential role of CTSL in the defense mechanism that helps BSFL to survive against pathogens in a microbial-rich environment.

Vibrio α-hemolysins (αHLs) are β-pore-forming toxins secreted by Vibrio pathogens, crucial for the facilitation of bacterial infections through host cell lysis. These toxins are produced as inactive precursors, requiring proteolytic maturation and membrane association for activation within host tissues. Here, we investigate Vibrio campbellii αHL (VcαHL), and establish that its hemolytic activity is significantly stimulated by calcium ions, with an EC 50 that aligns with physiological calcium concentrations. Furthermore, we illustrate the vital contribution of calcium ions to the oligomerization of VcαHL on membranes. Using X-ray crystallography and cryo-electron microscopy, we decipher both the immature and assembled structures of VcαHL and elucidate the conformational changes corresponding to toxin assembly. We also identify a calcium-binding module that is integral for VcαHL’s calcium-dependent activation. These findings provide insights into the regulatory mechanisms of VcαHL and have the potential to inform the development of targeted therapeutic strategies against Vibrio infections. Vibrio α-hemolysins (αHLs) are toxins crucial for certain bacterial infections. Here the authors reveal that calcium ions boost the activity of a specific toxin, Vibrio campbellii αHL, and uncover its calcium-dependent activation mechanism.

Glucosinolates (GLSs) are a group of secondary metabolites that are involved in the defense of herbivores. In Arabidopsis thaliana , Glucosinolate Transporter 1 (AtGTR1) transports GLSs with high affinity via a proton gradient-driven process. In addition to transporting GLSs, AtGTR1 also transports phytohormones, jasmonic acid-isoleucine (JA-Ile), and gibberellin (GA). However, little is known about the mechanisms underlying the broad substrate specificity of AtGTR1. Here, we characterized the substrate preference of AtGTR1 by using a yeast uptake assay, and the results revealed that GLS transport rates are negatively correlated with the hydrophobicity of substrates. Interestingly, the AtGTR1 showed a higher substrate affinity for GLSs with higher hydrophobicity, suggesting a hydrophobic substrate binding pocket. In addition, competition assays revealed that JA, salicylic acid (SA), and indole-3-acetic acid (IAA) competed with GLS for transport in yeast, suggesting a potential interaction of AtGTR1 with these phytohormones. To further characterize the functional properties of AtGTR1, mutagenesis experiments confirmed that the conserved EXXEK motif and Arg166 are essential for the GLS transport function. In addition, the purified AtGTR1 adopts a homodimeric conformation, which is possibly regulated by phosphorylation on Thr105. The phosphomimetic mutation, T105D, reduced its protein expression and completely abrogated its GLS transport function, indicating the essential role of phosphorylation on AtGTR1. In summary, this study investigated various factors associated with the GLS transport and increased our knowledge on the substrate preferences of AtGTR1. These findings contribute to understanding how the distribution of defense GLSs is regulated in plants and could be used to improve crop quality in agriculture.

This study investigates the tripole rainfall pattern in East Asia during the northern summer. The tripole pattern is characterized by a zonally elongated and meridionally banded structure with signs changing alternatively from 20° to 50°N along the East Asian coast. The positive (negative) phase of the pattern is characterized by more (less) rainfall in central-eastern China, Japan, and South Korea, and less (more) rainfall in northern and southern China. Asymmetry between the positive and negative phases is one of the key findings of this study. The tripole pattern is closely associated with two wavelike patterns: the Pacific–Japan pattern and the Silk Road pattern. The former, which emanates from the tropical western Pacific to extratropical East Asia, is more evident in the positive phase, while the latter, emanating across the Eurasian continent, is more evident in the negative phase. The positive phase appears to have a stronger tropical connection, while the negative phase has a stronger extratropical connection. The positive and negative phases are associated with the positive and negative SSTA in the equatorial eastern Pacific, respectively. It is suggested that in the positive phase the zonally oriented overturning circulation driven by the positive SSTA in the equatorial eastern Pacific induces heating anomalies in the tropical western Pacific, which in turn triggers a wavelike pattern emanating northward toward extratropical East Asia. This indirect SSTA effect is not evident in the negative phase, which is predominantly affected by the extratropical Eurasian wavelike perturbations. On the other hand, anomalous heating over the eastern Tibetan Plateau seems to induce the eastward-propagating wavelike structure in both phases. It is suggested that the tripole pattern is a result of the amplification of an intrinsic dynamic mode that can be triggered by various factors despite their different origins.

Leptospirosis is an overlooked zoonotic disease caused by pathogenic Leptospira depended on virulence of Leptospira and the host–pathogen interaction. Kidney is the major organ infected by Leptospira which causes tubulointerstitial nephritis. Leptospira outer membrane contains several virulence factors and an outer membrane protein A (OmpA) like protein (Loa22) is essential for virulence. Pull-down assays suggested that Loa22 was a potential Toll-Like Receptor 2 (TLR2) binding candidates from pathogenic Leptospira . Confocal microscopy was employed to observe the co-localization of TLR2 and Loa22-LPGN ( Leptospira peptidoglycan) complexes. Atomic force microscopy (AFM), side-directed mutagenesis, and enzyme-linked immunosorbent assay (ELISA) were performed to investigate the affinity between rLoa22, LPGN, and TLR2. Real time PCR was applied to measure the cytokines expression. Downstream signal transduction components were verified by western blot to evaluate the gene regulations. Mutation of two Loa22 key residues (Asp 122 and Arg 143 ) attenuated the affinities for LPGN. rLoa22-LPGN complexes were observed to co-localize with TLR2 and provoked inflammatory responses including CXCL8/IL8 , hCCL2/MCP-1 , and hTNF-α . Affinity studies suggested that Loa22-LPGN complexes elevated the affinity to TLR2 as compared to Loa22 protein. Downstream signals from TLR2 including p38, ERK, and JNK were regulated under rLoa22-LPGN complexes treatments. This study identified LPGN mediates interactions between Loa22 and TLR2 and induces downstream signals to trigger inflammatory responses. rLoa22-LPGN-TLR2 complexes reveal a novel binding mechanism for the innate immune system.

A model for the coupling of proton pumping and pyrophosphatase hydrolysis is proposed. Proton pumping in plants Two types of proton-pumping protein, vacuolar H + -ATPases and H + -translocating pyrophosphatases (H + -PPases), co-exist on plant vacuolar membranes and use ATP and pyrophosphate (respectively) as energy sources for proton translocation. Whereas vacuolar H + -ATPases have been studied quite extensively, the three-dimensional structure and detailed mechanisms underlying the hydrolytic and proton-translocation reactions of H + -PPases are unclear. This paper reports the crystal structure of an H + -PPase in the presence of a non-hydrolysable substrate analogue. An unusual proton-translocation pathway is formed by six core transmembrane helices. The authors propose a model for how proton pumping and pyrophosphatase hydrolysis are coupled. H + -translocating pyrophosphatases (H + -PPases) are active proton transporters that establish a proton gradient across the endomembrane by means of pyrophosphate (PP i ) hydrolysis 1 , 2 . H + -PPases are found primarily as homodimers in the vacuolar membrane of plants and the plasma membrane of several protozoa and prokaryotes 2 , 3 . The three-dimensional structure and detailed mechanisms underlying the enzymatic and proton translocation reactions of H + -PPases are unclear. Here we report the crystal structure of a Vigna radiata H + -PPase ( Vr H + -PPase) in complex with a non-hydrolysable substrate analogue, imidodiphosphate (IDP), at 2.35 Å resolution. Each Vr H + -PPase subunit consists of an integral membrane domain formed by 16 transmembrane helices. IDP is bound in the cytosolic region of each subunit and trapped by numerous charged residues and five Mg 2+ ions. A previously undescribed proton translocation pathway is formed by six core transmembrane helices. Proton pumping can be initialized by PP i hydrolysis, and H + is then transported into the vacuolar lumen through a pathway consisting of Arg 242, Asp 294, Lys 742 and Glu 301. We propose a working model of the mechanism for the coupling between proton pumping and PP i hydrolysis by H + -PPases.

Auxin regulates diverse processes involved in plant growth and development. AUX1 is the first identified and most widely investigated auxin importer, and plays an important role in root gravitropism and the development of lateral root and root hair. However, the regulation of auxin transport by AUX1 is still not well understood. In this study, we examined the effect of metal ions on AUX1 transport function and found that the activity could be specifically stimulated four times by K+. Further experiments revealed the preference of KF on the enhancement of transport activity of AUX1 over KCl, KBr, and KI. In addition, the interaction between K+ and AUX1 confers AUX1 more resistant to thermal stress but more vulnerable to proteolysis. Conventional chemical modification indicated that the extracellular acidic amino acids of AUX1 play a key role in the K+ stimulation. Site-specific mutagenesis showed that the replacement of Asp166, Asp293, and Asp312 of AUX1 to alanine deteriorated the K+-stimulated auxin transport. By contrast, when these residues were mutated to glutamate, lysine, or asparagine, only the D312E variant restored the IAA transport activity to the wild-type level. It is thus convinced that D312 is presumably the most promising residue for the K+ stimulation on AUX1.

This study explores the effects of pipe wall properties (thermal conductivity k and wall thickness tw) on the heat transfer performance of a rectangular thermosyphon with a phase change material (PCM) suspension and a geometric configuration (aspect ratio = 1; dimensionless heating section length = 0.8; dimensionless relative elevation between the cooling and the heating sections = 2) that ensures the optimum heat transfer efficiency in the cooling section. The following parameter ranges are studied: the dimensionless loop wall thickness (0 to 0.5), wall-to-fluid thermal conductivity ratio (0.1 to 100), modified Rayleigh number (1010 to 1011), and volumetric fraction of PCM particles (0 to 10%). The results show that appropriate selection of k and tw can lead to improved heat transfer effectiveness in the cooling section of the PCM suspension-containing rectangular thermosyphon.