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Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine involved in immune response in animals. However, the role of MIFs in plants such as Medicago truncatula, particularly in symbiotic nitrogen fixation, remains unclear. An investigation of M. truncatula-Sinorhizobium meliloti symbiosis revealed that MtMIF3 was mainly expressed in the nitrogen-fixing zone of the nodules. Silencing MtMIF3 using RNA interference (Ri) technology resulted in increased nodule numbers but higher levels of bacteroid degradation in the infected cells of the nitrogen-fixing zone, suggesting that premature aging was induced in MtMIF3-Ri nodules. In agreement with this conclusion, the activities of nitrogenase, superoxide dismutase and catalase were lower than those in controls, but cysteine proteinase activity was increased in nodulated roots at 28 days postinoculation. In contrast, the overexpression of MtMIF3 inhibited nodule senescence. MtMIF3 is localized in the plasma membrane, nucleus, and cytoplasm, where it interacts with methionine sulfoxide reductase B (MsrB), which is also localized in the chloroplasts of tobacco leaf cells. Taken together, these results suggest that MtMIF3 prevents premature nodule aging and protects against oxidation by interacting with MtMsrB.

This work was designed to prepare a novel NiS/KNbO3 p-n heterojunction composite for efficient photocatalytic nitrogen fixation under simulated sunlight. The NiS/KNbO3 photocatalyst was prepared through a two-step hydrothermal method. X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy analyses proved that NiS nanoparticles were closely decorated on the surface of KNbO3 nanorods, to facilitate the migration of electrons between the two semiconductors. Mott-Schottky analysis indicated that the Femi level of KNbO3 is higher than that of NiS. Thus, the electron migration from KNbO3 to NiS occurs naturally. This migration elevates the band potential of NiS, makes NiS/KNbO3 form a type-II photocatalyst, and generates an internal electric field in the composite. The synergetic effect of the internal electric field and the type-II band structure endows NiS/KNbO3 with high efficiency in the spatial separation of photogenerated electron-hole pairs, verified by electrochemical impedance spectroscopy and transient photocurrent experiments. Therefore, NiS/KNbO3 presents good efficiency in photocatalytic N2 reduction with an NH3 production rate of 155.6 μmol·L−1·g−1·h−1, which is 1.9 and 6.8 times higher than those of KNbO3 and NiS, respectively. UV–visible diffuse reflectance spectroscopy and N2-adsorption experiments were also performed to investigate the effect of light absorption and surface area on the photocatalytic reaction. Nevertheless, compared with the great promotion effect in charge separation, the contribution of the two factors can be ignored.

Graphical abstract, Highlights • Ag nanoparticles were loaded on PbBiO2I nanosheets via a photodepostion method. • Ag/PbBiO2I can harvest ultrasonic vibration energy to degrade RhB. • The degradation rate of the optimal Ag/PbBiO2I is 6.8 times faster than PbBiO2I. • Ag nanoparticles act as electron trappers to improve the piezoinduced charge carriers., Ag/PbBiO2I nanocomposite was synthesized and firstly applied in piezocatalytic degradation of rhodamine B (RhB) under ultrasonic vibration. The two-dimensional structure endows PbBiO2I nanosheets piezoelectric property, so that it can drive the piezocatalytic reaction under ultrasonic vibration. The loading of Ag nanoparticles forms Schottky barriers between the Ag-PbBiO2I contact region, which improves the separation of charge carriers and subsequently increases the piezocatalytic efficiency. The RhB degradation rate of the optimal Ag/PbBiO2I sample is 0.0165 min−1, which reaches 6.8 times that of pure PbBiO2I. This work indicates that the PbBiO2I nanosheet shows promising potential in utilizing ultrasonic vibration energy.

The establishment of symbiosis between legume and rhizobium results in the formation of nodule. Phytocyanins (PCs) are a class of plant-specific blue copper proteins, playing critical roles in plant development including nodule formation. Although a few PC genes have been isolated from nodules, their functions are still unclear. Here, we performed a genome-wide identification of PC family in seven sequenced legume species (Medicago truncatula, Glycine max, Cicer arietinum, Cajanus cajan, Lotus japonicus, Vigna angularis and Phaseolus vulgaris) and found PCs experienced a remarkable expansion in M. truncatula and G. max. Further, we conducted an in-depth analysis of PC family in the model legume M. truncatula. Briefly, 82 MtPCs were divided into four subfamilies and clustered into seven clades, with a large proportion of tandem duplications and various cross-tissues expression patterns. Importantly, some PCs, such as MtPLC1, MtENODL27 and MtENODL28 were preferentially expressed in nodules. Further, RNA interference (RNAi) experiment revealed the knockdown of MtENDOL27 and MtENDOL28 impaired rhizobia infection, nodule numbers and nitrogenase activity. Moreover, in the MtENODL27-RNAi nodules, the infected cells were reduced and the symbiosomes did not reach the elongated stage, indicating MtENDOL27 is required for rhizobia infection and nodule development. In addition, co-expression analysis showed MtPLC1, MtENODL27 and MtENODL28 were grouped into two different functional modules and co-expressed with the known symbiotic nitrogen fixation-related genes, suggesting that they might participate in nodulation via different ways. In summary, this study provides a useful resource for future researches on the structure and function of PCs in nodulation.

The RNA-dependent RNA polymerases (RdRPs) encoded by RNA viruses represent a unique class of nucleic acid polymerases. RdRPs are essential in virus life cycle due to their central role in viral genome replication/transcription processes. However, their contribution in host adaption has not been well documented. By solving the RdRP crystal structure of the tick-borne encephalitis virus (TBEV), a tick-borne flavivirus, and comparing the structural and sequence features with mosquito-borne flavivirus RdRPs, we found that a region between RdRP catalytic motifs B and C, namely region B-C, clearly bears host-related diversity. Inter-virus substitutions of region B-C sequence were designed in both TBEV and mosquito-borne Japanese encephalitis virus backbones. While region B-C substitutions only had little or moderate effect on RdRP catalytic activities, virus proliferation was not supported by these substitutions in both virus systems. Importantly, a TBEV replicon-derived viral RNA replication was significantly reduced but not abolished by the substitution, suggesting the involvement of region B-C in viral and/or host processes beyond RdRP catalysis. A systematic structural analysis of region B-C in viral RdRPs further emphasizes its high level of structure and length diversity, providing a basis to further refine its relevance in RNA virus-host interactions in a general context.

This work was designed to prepare a novel NiS/KNbO

Leaf necrosis induced by fungal pathogens is one of the most devastating diseases of yam. The objectives of this study were to examine the production of defensive phytohormones and perform a comparative transcriptome analysis between two yam cultivars with different resistance levels against Botrytis cinerea inoculation. After inoculation with B. cinerea, the endogenous ethylene level was found to have accumulated to a higher level in the MH1 resistant cultivar. Meanwhile, expression profiles identified differential defense regulation of ethylene pathway in MH1 (versus susceptible cv. MH3) in response to B. cinerea. A number of ethylene-synthesis and -responsive genes were expressed at higher levels in MH1 than in MH3 after inoculation. Furthermore, ethylene supplementation in MH3 plants by ethephon spraying indeed enhanced the resistance against B. cinerea and Colletotrichum alatae, and elevated the expression of DaEIN2 and DaERF96. Our work improves understanding of defense mechanism and highlights the function of ethylene potentially utilized for yam protection against diseases.

Graph classification aims to extract accurate information from graph-structured data for classification and is becoming more and more important in the graph learning community. Although Graph Neural Networks (GNNs) have been successfully applied to graph classification tasks, most of them overlook the scarcity of labeled graph data in many applications. For example, in bioinformatics, obtaining protein graph labels usually needs laborious experiments. Recently, few-shot learning has been explored to alleviate this problem with only a few labeled graph samples of test classes. The shared sub-structures between training classes and test classes are essential in the few-shot graph classification. Existing methods assume that the test classes belong to the same set of super-classes clustered from training classes. However, according to our observations, the label spaces of training classes and test classes usually do not overlap in a real-world scenario. As a result, the existing methods don't well capture the local structures of unseen test classes. To overcome the limitation, in this paper, we propose a direct method to capture the sub-structures with a well initialized meta-learner within a few adaptation steps. More specifically, (1) we propose a novel framework consisting of a graph meta-learner, which uses GNNs based modules for fast adaptation on graph data, and a step controller for the robustness and generalization of meta-learner; (2) we provide quantitative analysis for the framework and give a graph-dependent upper bound of the generalization error based on our framework; (3) the extensive experiments on real-world datasets demonstrate that our framework gets state-of-the-art results on several few-shot graph classification tasks compared to baselines.

This study aimed to simultaneously enhance the strength and ductility of films by adding graphene oxide (GO) into the sodium alginate (SA)-gelatin film system to prepare SA-gelatin-GO ternary composite films. The effects of the SA/gelatin weight ratio and the GO content on the morphology, structural, mechanical, hydrophobic, water vapor barrier, hygroscopic, and optical properties of composite films were investigated. Results showed that tensile strength and elongation at break values of the composite film with 0.5% GO content were significantly improved from 37.00 to 48.01 MPa and 20.19% to 25.75%, respectively, compared with the SA-gelatin film without GO, suggesting GO with the content of 0.5% simultaneously enhance the strength and ductility of the SA-gelatin film, which was due to the interaction of hydrogen bonds and the good dispersibility of GO in the film matrix. The surface hydrophobicity of composite films increased first and then decreased with increasing GO content. In addition, the hygroscopicity of composite films reduced due to the GO addition, especially when the GO content was 0.25%. The SA-gelatin-GO ternary composite films provide a good select for food packaging materials, especially the materials that require high strength and fine ductility.

Tick-borne encephalitis virus (TBEV) is one of the flaviviruses that targets the CNS and causes encephalitis in humans. The mechanism of TBEV that causes CNS destruction remains unclear. It has been reported that RANTES-mediated migration of human blood monocytes and T lymphocytes is specifically induced in the brain of mice infected with TBEV, which causes ensuing neuroinflammation and may contribute to brain destruction. However, the viral components responsible for RANTES induction and the underlying mechanisms remain to be fully addressed. In this study, we demonstrate that the NS5, but not other viral proteins of TBEV, induces RANTES production in human glioblastoma cell lines and primary astrocytes. TBEV NS5 appears to activate the IFN regulatory factor 3 (IRF-3) signaling pathway in a manner dependent on RIG-I/MDA5, which leads to the nuclear translocation of IRF-3 to bind with RANTES promoter. Further studies reveal that the activity of RNA-dependent RNA polymerase (RdRP) but not the RNA cap methyltransferase is critical for TBEV NS5–induced RANTES expression, and this is likely due to RdRP-mediated synthesis of dsRNA. Additional data indicate that the residues at K359, D361, and D664 of TBEV NS5 are critical for RdRP activity and RANTES induction. Of note, NS5s from other flaviviruses, including Japanese encephalitis virus, West Nile virus, Zika virus, and dengue virus, can also induce RANTES expression, suggesting the significance of NS5-induced RANTES expression in flavivirus pathogenesis. Our findings provide a foundation for further understanding how flaviviruses cause neuroinflammation and a potential viral target for intervention.

The study aimed to investigate the antioxidant and ultraviolet-shielding properties of sodium alginate-gelatin-graphene oxide ternary films by adding rosemary extract (RE). Polyvinylpyrrolidone (PVP) was used to overcome the shortcoming that RE decreased the mechanical properties of films. The addition of 0.1 % PVP enhanced the tensile strength of the films by 13.61 MPa without significant reduction in elongation at break. RE markedly decreased the light transmittance of PVP-containing film by 39.40 %–52.55 % in the 300–400 nm region, showing excellent ultraviolet-shielding capacity of RE. Additionally, films with RE and PVP showed superior 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity in water and 50 % ethanol. The peroxide value of soybean oil sealed with films containing RE and PVP was 0.51 times of that sealed with the ternary film after 30 days of storage, indicating excellent antioxidant activity of RE. This study provided a prospect for application of sodium alginate-gelatin based functional packaging materials.

Ecological stoichiometry has been widely studied in terrestrial ecosystems, but these studies have been limited in terms of symbiotic association between alfalfa and arbuscular mycorrhizal fungi (AMF), especially during regrowth. To evaluate the effect of AMF on the regrowth and C:N:P stoichiometry of alfalfa (Medicago sativa L.) under well-watered and drought conditions, alfalfa plants inoculated with AMF (Rhizophagus irregularis, M), nitrogen-fixing bacteria (Sinorhizobium, R), both nitrogen-fixing bacteria and AMF or no inoculations (CK) were evaluated in a pot experiment under controlled conditions. The biomass and organic carbon (C), nitrogen (N) and phosphorus (P) nutritional status of plant leaves and roots were measured under two water treatments during regrowth. Water deficit reduced the accumulation of dry matter and the concentrations of C and N in leaves and P in roots but increased the concentrations of P in leaves and C and N in roots of alfalfa during regrowth. Compared to CK plants, inoculation significantly improved the regrowth biomass and the concentrations of C, N and P in the leaves and roots and especially increased P levels when the plant were inoculated with AMF. However, this effect of microbes on alfalfa regrowth was dependent on the soil water status. Drought reduced the C:N and C:P in the leaves and the C:N in roots, while N:P and C:P increased in the roots. Inoculation of AMF decreased the C:P and N:P in the leaves and the C:N and C:P in the roots, whereas it increased the C:N under water stress. These results indicate that AMF play a significant role in regrowth and C:N:P ecological stoichiometry after defoliation by influencing C assimilation, N and P uptake and that the responses in the leaves and the roots are opposite.

Glutathione S-transferases are important enzymes in protecting cells by scavenging reactive oxygen species induced by various stresses. In this study, a novel GST gene, MsGST (KM044312), was cloned and characterized from alfalfa. The open reading frame of MsGST contains 660bp nucleotides, encoding 219 amino acid residues. Amino acid sequence alignment indicated that the deduced MsGST protein was highly homologous to other plant tau class GST sequences. According to amino acid phylogenetic analysis, the MsGST gene was clustered into the same branch with other legume plants. Real-time quantitative PCR (qRT-PCR) revealed that the expression levels of MsGST were up-regulated in both shoots and roots under ABA treatment and various stresses, including salt, drought, cold and heat stress. The effect of nodules on MsGST gene expression indicated that the induction of MsGST expression by abiotic stress is independent of rhizobium symbiosis. In conclusion, the MsGST gene may be involved in response to different abiotic stresses in alfalfa.