Search

Abstract RNA recombination is one of the two major factors that create RNA genome variability. Assessing its incidence in plant RNA viruses helps understand the formation of new isolates and evaluate the effectiveness of crop protection strategies. To search for recombination in Soybean mosaic virus (SMV), the causal agent of a worldwide seed-borne, aphid-transmitted viral soybean disease, we obtained all full-length genome sequences of SMV as well as partial sequences encoding the N-terminal most (P1 protease) and the C-terminal most (capsid protein; CP) viral protein. The sequences were analyzed for possible recombination events using a variety of automatic and manual recombination detection and verification approaches. Automatic scanning identified 3, 10, and 17 recombination sites in the P1, CP, and full-length sequences, respectively. Manual analyses confirmed 10 recombination sites in three full-length SMV sequences. To our knowledge, this is the first report of recombination between distinct SMV pathotypes. These data imply that different SMV pathotypes can simultaneously infect a host cell and exchange genetic materials through recombination. The high incidence of SMV recombination suggests that recombination plays an important role in SMV evolution. Obtaining additional full-length sequences will help elucidate this role.

Abstract Background Virus infection induces the activation and suppression of global gene expression in the host. Profiling gene expression changes in the host may provide insights into the molecular mechanisms that underlie host physiological and phenotypic responses to virus infection. In this study, the Arabidopsis Affymetrix ATH1 array was used to assess global gene expression changes in Arabidopsis thaliana plants infected with Plum pox virus (PPV). To identify early genes in response to PPV infection, an Arabidopsis synchronized single-cell transformation system was developed. Arabidopsis protoplasts were transfected with a PPV infectious clone and global gene expression changes in the transfected protoplasts were profiled. Results Microarray analysis of PPV-infected Arabidopsis leaf tissues identified 2013 and 1457 genes that were significantly (Q ≤ 0.05) up- (≥ 2.5 fold) and downregulated (≤ -2.5 fold), respectively. Genes associated with soluble sugar, starch and amino acid, intracellular membrane/membrane-bound organelles, chloroplast, and protein fate were upregulated, while genes related to development/storage proteins, protein synthesis and translation, and cell wall-associated components were downregulated. These gene expression changes were associated with PPV infection and symptom development. Further transcriptional profiling of protoplasts transfected with a PPV infectious clone revealed the upregulation of defence and cellular signalling genes as early as 6 hours post transfection. A cross sequence comparison analysis of genes differentially regulated by PPV-infected Arabidopsis leaves against uniEST sequences derived from PPV-infected leaves of Prunus persica, a natural host of PPV, identified orthologs related to defence, metabolism and protein synthesis. The cross comparison of genes differentially regulated by PPV infection and by the infections of other positive sense RNA viruses revealed a common set of 416 genes. These identified genes, particularly the early responsive genes, may be critical in virus infection. Conclusion Gene expression changes in PPV-infected Arabidopsis are the molecular basis of stress and defence-like responses, PPV pathogenesis and symptom development. The differentially regulated genes, particularly the early responsive genes, and a common set of genes regulated by infections of PPV and other positive sense RNA viruses identified in this study are candidates suitable for further functional characterization to shed lights on molecular virus-host interactions.

Summary: Endocytosis and endosomal trafficking play essential roles in diverse biological processes including responses to pathogen attack. It is well established that animal viruses enter host cells through receptor‐mediated endocytosis for infection. However, the role of endocytosis in plant virus infection still largely remains unknown. Plant dynamin‐related proteins 1 (DRP1) and 2 (DRP2) are the large, multidomain GTPases that participate together in endocytosis. Recently, we have discovered that DRP2 is co‐opted by Turnip mosaic virus (TuMV) for infection in plants. We report here that DRP1 is also required for TuMV infection. We show that overexpression of DRP1 from Arabidopsis thaliana (AtDRP1A) promotes TuMV infection, and AtDRP1A interacts with several viral proteins including VPg and cylindrical inclusion (CI), which are the essential components of the virus replication complex (VRC). AtDRP1A colocalizes with the VRC in TuMV‐infected cells. Transient expression of a dominant negative (DN) mutant of DRP1A disrupts DRP1‐dependent endocytosis and supresses TuMV replication. As adaptor protein (AP) complexes mediate cargo selection for endocytosis, we further investigated the requirement of AP in TuMV infection. Our data suggest that the medium unit of the AP2 complex (AP2β) is responsible for recognizing the viral proteins as cargoes for endocytosis, and knockout of AP2β impairs intracellular endosomal trafficking of VPg and CI and inhibits TuMV replication. Collectively, our results demonstrate that DRP1 and AP2β are two proviral host factors of TuMV and shed light into the involvement of endocytosis and endosomal trafficking in plant virus infection. Significance Statement: Endocytosis proteins DRP1 and AP2β are two proviral host factors of turnip mosaic virus (TuMV). TuMV proteins VPg and cylindrical inclusion (CI) are recognized by the AP2 complex and interact with DRP1/2 to enter the endocytic and endosomal trafficking pathway, which promotes the intracellular trafficking of the viral proteins as well as associated endosomes to the replication site possibly for assembly of the virus replication complex to support robust virus replication. [ABSTRACT FROM AUTHOR]

Spring failure is one of the critical causes of the structural damage and low screening efficiency of mining vibrating screens. Therefore, spring failure diagnosis is necessary to prompt maintenance for the safety and reliability of mining vibrating screens. In this paper, a spring failure diagnosis approach is developed. A finite element model of mining vibrating screens is established. Simulations are carried out and the spring failure influence rules of spring failure on the dynamic characteristics of mining vibrating screens are obtained. These influence rules indicate that the amplitude variation coefficients (AVCs) of the four spring seats in the x, y, and z directions can reveal two kinds of single spring failure and four kinds of double spring failure, which are useful for diagnosing spring failure. Furthermore, experiments are conducted. Comparison analyses of the experimental results and simulation results indicate that the proposed approach is capable of revealing various kinds of spring failure. Therefore, this approach provides useful information for diagnosing spring failure and guiding technical staff to routinely maintain mining vibrating screens. [ABSTRACT FROM AUTHOR]

Two polyurethanes were prepared through the reaction of 1,6-diisocyanatohexane (HDI) with two kinds of alcoholates. The first alcoholate was synthesized from alcoholized lactide (PLA) and dodecafluoroheptyl methacrylate (DFHMA) with the solid super acid (SO42−/ZrO) acting as the catalyst, and the other alcoholate was a mixture of PLA and DFHMA. The composition and structure of these two polyurethanes were investigated by infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The mass loss, attachment of bacteria and algae, and the water contact angle were used to evaluate the degradable and antifouling performance of the two polyurethane coatings. The results showed that the maximum contact angle of PLIPFI reached 129°, its mass loss was higher than 10% in 65 days, and after 65 days, the mass loss appeared to be stable, and the antiadhesion performance of the polyurethanes coatings was also enhanced. All of these results indicated that the PU modified with a graft segment may be promising for obtaining antifouling materials that not only can resist the adhesion of microorganisms but also show self-renewal. [ABSTRACT FROM AUTHOR]

This study proposes an algorithm for the simultaneous identification of residual unbalance and bearing dynamic coefficients of a single-disc and single-span rotor based on the unbalance response. The rotor is modelled as a homogeneous and continuous Rayleigh beam. A fourth-order non-homogeneous partial differential equation set with a homogeneous boundary condition is solved to obtain the analytical solution, which expresses the unbalance response as a function of position, rotor unbalance, and bearing stiffness and damping coefficients. Accordingly, the inverse problem is studied. A novel algorithm that can be applied to both a rolling-bearing rotor and an oil journal bearing rotor is proposed to identify the rotor unbalance during operation. Another novel algorithm is developed to identify the bearing stiffness and damping coefficients for a rolling-bearing rotor. Only four measured unbalance responses are required in the two above-mentioned algorithms. Thus, a simultaneous identification of the rotor unbalance and the roll-bearing dynamic coefficients can be achieved. Furthermore, only a measured response registered for the disc, the two bearings and any other selected cross-section of the rotor shaft under steady-state operating conditions is required. Numerical simulation shows that the proposed identification algorithms have excellent detection capabilities. In summary, the proposed algorithms provide an efficient means for rotor parameter identification without test runs or external excitations. [ABSTRACT FROM AUTHOR]

Viruses are small parasites that can cause significant damage to their host organisms. Most viruses belong to the class of positive-sense single-stranded RNA (+ssRNA) viruses, which includes well-known viruses like SARS-CoV-2 and dengue. Recently, hidden protein-coding open reading frames (ORFs) have been discovered in the genomes of various viruses, including +ssRNA and ssDNA viruses. These hidden proteins have important biological functions and challenge previous assumptions about viral protein expression. The discovery of these hidden proteins expands our understanding of viral proteomes and could lead to new strategies for preventing and controlling viral infections. [Extracted from the article]