The Magnaporthe oryzae effector Avr-PikD suppresses rice immunity by inhibiting an LSD1-like transcriptional activator

Avirulence effectors(Avrs),encoded by plant pathogens,can be recognized by plants harboring the corresponding resistance proteins,thereby initiating effector-triggered immunity(ETI).In susceptible plants,however,Avrs can function as effectors,facilitating infection via effector-triggered susceptibility(ETS).Mechanisms of Avr-mediated ETS remain largely unexplored.Here we report that the Magnaporthe oryzae effector Avr-PikD enters rice cells via the canonical cytoplasmic secretion pathway and suppresses rice basal defense.Avr-PikD interacts with an LSD1-like transcriptional activator AKIP30 of rice,and AKIP30 is also a positive regulator of rice immunity,whereas Avr-PikD impedes its nuclear localization and suppresses its transcriptional activity.In summary,M.oryzae delivers Avr-PikD into rice cells to facilitate ETS by inhibiting AKIP30-mediated transcriptional regulation of immune response against M.oryzae.

Puccinia triticina effector protein Pt_21 interacts with wheat thaumatin-like protein TaTLP1 to inhibit its antifungal activity and suppress wheat apoplast immunity

Puccinia triticina(Pt), as the causal agent of wheat leaf rust, employs a plethora of effector proteins to modulate wheat immunity for successful colonization. Understanding the molecular mechanisms underlying Pt effector-mediated wheat susceptibility remains largely unexplored. In this study, an effector Pt_21 was identified to interact with the apoplast-localized wheat thaumatin-like protein TaTLP1 using a yeast two-hybrid assay and the Pt_21-TaTLP1 interaction was characterized. The interaction between Pt_21 and TaTLP1 was validated by in vivo co-immunoprecipitation assay. A TaTLP1 variant,TaTLP1C71A, that was identified by the site-directed mutagenesis failed to interact with Pt_21. Pt_21was able to suppress Bax-mediated cell death in leaves of Nicotiana benthamiana and inhibit TaTLP1-mediated antifungal activity. Furthermore, infiltration of recombinant protein Pt_21 into leaves of transgenic wheat line overexpressing TaTLP1 enhanced the disease development of leaf rust compared to that in wild-type leaves. These findings demonstrate that Pt_21 suppresses host defense response by directly targeting wheat TaTLP1 and inhibiting its antifungal activity, which broadens our understanding of the molecular mechanisms underlying Pt effector-mediated susceptibility in wheat.

A Meloidogyne incognita effector Minc03329 suppresses plant immunity and promotes parasitism

Meloidogyne incognita is a devastating plant-parasitic nematode.Effectors play important roles during the stages of nematodes infection and parasitism,but their molecular functions remain largely unknown.In this study,we characterized a new effector,Minc03329,which contains signal peptide for secretion and a C-type lectin domain.The yeast signal sequence trap experiments indicated that the signal peptide of Minc03329 is functional.In situ hybridization showed that Minc03329 was specifically expressed in the subventral esophageal gland.Real-time qPCR confirmed that the expression level of Minc03329 transcript was significantly increased in pre-parasitic and parasitic second-stage juveniles(pre-J2s and par-J2s).Tobacco rattle virus(TRV)-mediated gene silencing of Minc03329 in host plants largely reduced the pathogenicity of nematodes.On the contrary,ectopic expression of Minc03329 in Arabidopsis thaliana significantly increased plant susceptibility to nematodes.Transient expression of Minc03329 in Nicotiana benthamiana leaves suppressed the programmed cell death triggered by the pro-apoptotic protein BAX.Moreover,the transcriptome analysis of Minc03329-transgenic Arabidopsis and wild type revealed that many defense-related genes were significantly down-regulated.Interestingly,some different expressed genes were involved in the formation of nematode feeding sites.These results revealed that Minc03329 is an important effector for M.incognita,suppressing host defense response and promoting pathogenicity.

Design of Drilling and Riveting Multi-functional End Effector for CFRP and Aluminum Components in Robotic Aircraft Assembly

To fulfill the demands for higher quality,efficiency and flexibility in aviation industry,a multi-functional end effector is designed to automate the drilling and riveting processes in assembling carbon fiber reinforced polymer(CFRP)and aluminum components for a robotic aircraft assembly system.To meet the specific functional requirements for blind rivet installation on CFRP and aluminum materials,additional modules are incorporated on the end effector aside of the basic processing modules for drilling.And all of these processing modules allow for a onestep-drilling-countersinking process,hole inspection,automatic rivet feed,rivet geometry check,sealant application,rivet insertion and installation.Besides,to guarantee the better quality of the hole drilled and joints riveted,several online detection and adjustment measures are applied to this end effector,including the reference detection and perpendicular calibration,which could effectively ensure the positioning precision and perpendicular accuracy as demanded.Finally,the test result shows that this end effector is capable of producing each hole to a positioning precision within ±0.5 mm,aperpendicular accuracy within 0.3°,a diameter tolerance of H8,and a countersink depth tolerance of±0.01 mm.Moreover,it could drill and rivet up to three joints per minute,with acceptable shearing and tensile strength.

Design Schemes and Comparison Research of the End-effector of Large Space Manipulator

The end-effector of the large space manipulator is employed to assist the manipulator in handling and manipulating large payloads on orbit.Currently,there are few researches about the end-effector,and the existing end-effectors have some disadvantages,such as poor misalignment tolerance capability and complex mechanical components.According to the end positioning errors and the residual vibration characters of the large space manipulators,two basic performance requirements of the end-effector which include the capabilities of misalignment tolerance and soft capture are proposed.And the end-effector should accommodate the following misalignments of the mechanical interface.The translation misalignments in axial and radial directions and the angular misalignments in roll,pitch and yaw are ±100 mm,100 mm,±10°,±15°,±15°,respectively.Seven end-effector schemes are presented and the capabilities of misalignment tolerance and soft capture are analyzed elementarily.The three fingers-three petals end-effector and the steel cable-snared end-effector are the most feasible schemes among the seven schemes,and they are designed in detail.The capabilities of misalignment tolerance and soft capture are validated and evaluated,through the experiment on the micro-gravity simulating device and the dynamic analysis in ADAMS software.The results show that the misalignment tolerance capabilities of these two schemes could satisfy the requirement.And the translation misalignment tolerances in axial and radial directions and the angular misalignment tolerances in roll,pitch and yaw of the steel cable-snared end-effector are 30mm,15mm,6°,3° and 3° larger than those of the three fingers-three petals end-effector,respectively.And the contact force of the steel cable-snared end-effector is smaller and smoother than that of the three fingers-three petals end-effector.The end-effector schemes and research methods are beneficial to the developments of the large space manipulator end-effctor and the space docking mechanism.

Yersinia type Ⅲ effectors perturb host innate immune responses

The innate immune system is the first line of defense against invading pathogens. Innate immune cells recognize molecular patterns from the pathogen and mount a response to resolve the infection. The production of proinflammatory cytokines and reactive oxygen species, phagocytosis, and induced programmed cell death are processes initiated by innate immune cells in order to combat invading pathogens. However, pathogens have evolved various virulence mechanisms to subvert these responses. One strategy utilized by Gram-negative bacterial pathogens is the deployment of a complex machine termed the type Ⅲ secretion system(T3SS). The T3SS is composed of a syringe-like needle structure and the effector proteins that are injected directly into a target host cell to disrupt a cellular response. The three human pathogenic Yersinia spp.(Y. pestis, Y. enterocolitica, and Y. pseudotuberculosis) are Gramnegative bacteria that share in common a 70 kb virulence plasmid which encodes the T3 SS. Translocation of the Yersinia effector proteins(YopE, YopH, YopT, YopM, YpkA/YopO, and YopP/J) into the target host cell results in disruption of the actin cytoskeleton to inhibit phagocytosis, downregulation of proinflammatory cytokine/chemokine production, and induction of cellular apoptosis of the target cell. Over the past 25 years, studies on the Yersinia effector proteins have unveiled tremendous knowledge of how the effectors enhance Yersinia virulence. Recently, the long awaited crystal structure of YpkA has been solved providing further insights into the activation of the YpkA kinase domain. Multisite autophosphorylation by YpkA to activate its kinase domain was also shown and postulated to serve as a mechanism to bypass regulation by host phosphatases. In addition, novel Yersinia effector protein targets, such as caspase-1, and signaling pathways including activation of the inflammasome were identified. In this review, we summarize the recent discoveries made on Yersinia effector proteins and their contribution to Yersinia pathogenesis.

Neural regeneration after peripheral nerve injury repair is a system remodelling process of interaction between nerves and terminal effector

In China, there are approximately 20 million people suffering from peripheral nerve injury and this number is increasing at a rate of 2 million per year. These patients cannot live or work independently and are a heavy responsibility on both family and society because of extreme disability and dysfunction caused by peripheral nerve injury （PNI）. Thus, repair of PNI has become a major public health issue in China.

IN VITRO AND IN VIVO CHEMOTACTIC EFFECT OF MIP-1a GENE TRANSFECTED TUMOR VACCINE ON IMMUNE EFFECTOR CELLS

Vaccination with chemokine genetransfected tumor cells may be a new apporach to cancer treatment. Macrohage inflammatory protein1α (MIP1α) is a new type of chemokines which has chemotactic activity on effector cells. In the present study, the B16 melanoma cells were transfected with recombinant adenovirus harboring murine MIP1α gene. The biological characteristics of the MIP1α gene transfected B16 melanoma cells were investigated. The level of MIP1α in the supernatant of genetransfected melanoma cells was 368±24 ng/ml/106/24hr. This supernatant showed strong chematactic activity for NK cells, CD4+ T cells, CD8+ T cells or the freshly isolated peritoneal macrophages. Though the in vitro growth were not altered, the tumorigenicity of the genetransfected B16 melanoma cells decreased signicantly. The infiltration of inflammatory cells into the tumor mass formed by MIP1α genetransfected B16 cells were much more obvious than that by wildtype B16 cells or B16 cells transfected with the control gene. However, the survival time of the mice bearing B16 melanoma cells transfected with MIP1α gene was not prolonged and the NK, CTL activity remianed unchanged. We suggested that the in vivo phenomenon may be related to the high toxicity of the MIP1 α as a strong nonspecific inflammatory mediator.

Regulation of neuroinflammatory properties of glial cells by T cell effector molecules

Multiple sclerosis （MS） is a chronic inflammatory and neurodegenerative disorder that is thought to be mediated by autoreactive T lymphocytes that find their way into the central nervous system （CNS）. The pathological mechanism of MS is still being elucidated but it involves complex interactions between infiltrating immune cells and resi- dent glial cells within the CNS that culminate into strong neuroinflammation and axonal damage.

Adhesion and cytotoxicity susceptibility of B16 melanoma cells to immune effector cells enhanced after IL-2, IL-4 or IL-6 gene-transfection

The elimination of the tumor is closely relatedwith the sensitivity of tumor cells to the cytotoxicityof immune effector cells. We supposed that cytokinegenetransfection may increase the cytotoxicitysusceptibility of tumor cells to effector cells, and as aconsequence, the tumorigenicity decreased. Beforekilling tumor cells, effector cells required first torecognize non-specific surface adhesion molecules

The new effector AbSCP1 of foliar nematode(Aphelenchoides besseyi) is required for parasitism rice

Plant parasitic nematodes secrete effector proteins to parasitize hosts successfully. Of these proteins, serine carboxypeptidases have critical roles in pathogenicity. This study investigated the role of new effector AbSCP1 in Aphelenchoides besseyi pathogenicity. In situ hybridization and qRT-PCR analyses indicated that AbSCP1 was exclusively expressed in the esophageal glands and upregulated in juveniles. Subcellular localization assays indicated that the protein was expressed in the nucleus. The ability to hydrolyze C-terminal amino acid residues was proven for AbSCP1. Moreover, RNAi significantly reduced the expression of AbSCP1 and RNAi-treated nematodes’ reproductive potential. Pathogenicity assays on rice showed that RNAi-treated nematodes were less pathogenic than the untreated control groups. These results suggest the important role of AbSCP1 in the A. besseyi infection process.

UVI_02019870, a Puptive Effector from Ustilaginoidea virens, Interacts with a Chloroplastic-Like Protein OsCPL1

Ustilaginoidea virens,which causes rice false smut(RFS),is one of the most detrimental rice fungal diseases and poses a severe threat to rice production and quality.Effectors in U.virens often act as a group of essential virulence factors that play crucial roles in the interaction between host and the pathogen.Thus,the functions of individual effectors in U.virens need to be further explored.Here,we found a small secreted hypersensitive response-inducing protein UVI_02019870 was highly conserved in fungi.Furthermore,we performed Y2H and BiFC assay to demonstrated UVI_02019870 interacted with OsCPL1,which was predicted as a chloroplast precursor to regulate chloroplast signaling pathways.Our data provide a theory for gaining an insight into the molecular mechanisms underlying the UVI_02019870 virulence function.

Bioinformatic Analysis of Potential Pathogenicity Effectors of <i>Candidatus</i>Liberibacter asiaticus, Causal Agent of Citrus Huanglongbing

Huanglongbing (HLB) or citrus greening is currently the most important citrus disease, caused by the bacterium Candidatus Liberibacter asiaticus (CLas). The impossibility of isolating it causes understanding its pathogenic mechanisms to be a complicated task. Recent studies identified 16 proteins with the signal peptide needed to be secreted in the plant and cause the disease. The present study aims to perform a bioinformatic analysis of these proteins with the function prediction approach by gene ontology (GO) and the detection of conserved domains. It was observed that of the 16 proteins analyzed not all are found in different infective strains reported in the literature. The GO analysis allowed us to relate different proteins with the biological process of energy and pathogenic activity, especially CLIBASIA_03315 and CLIBASIA_05115, respectively. The domain analysis allowed the observation of a β-CA domain, tentatively related to the damage caused to the chloroplast and a PAAR domain associated with the T6SS secretory system. Our results provide information on the possible function of potential pathogenicity effectors in CLas.

CD_4^(+) EFFECTOR CELLS DEFAULT TO THE TH2 PATHWAY IN INTERFERONγ-DEFICIENT

Mice with homologous disruption of the interferon γ(IFN-γ) gene on the C57BL/6 background were infected witly Leishmania major and the immune response assessed. In contrast to wild-type or heterozygous knockout mice,deficient animals were unable to restrict growth of the parasite and suffered lethal infection over 6￣8 wk.Although wild-type and heterozygous littermates developed CD4+ cells that contained transcripts for IFN-γ and lymphotoxin,tipical of T helper type 1(Th1) cells, the knockout mice developed CD+4 cells that contained transcripts for interleukin 4(IL-4),IL-5,and IL13,typical of Th2 cells. ELISPOT assays confirmed the reciprocal patterns of IFN-γ or IL-4 production by T cells in similar frequencies in the respective groups of mice,and antibody analysis confirmed the presence of Th2-mediated isotype switching in the knockout mice. These data suggest that CD4+ T cells that normally respond to antigens by differentiation to Th1 cells default to the Th2 pathway in the absence of endogenous IFN-γ.

Memory AND effector cells in children with bacterial infections of the gastrointestinal and respiratory tracts

Infections in infants and children under five years of age are a public health in México and are one of the major causes of death. Methods In this study, lymphocyte immunophenotyping for CD3+ (T-cells), CD3+CD4+, CD3+CD8+, CD3+CD19+, CD3+CD16/56+, CD45RA+, CD45RO+, CD62L- and CD28- were determined in the whole blood of gastrointestinal and respiratory bacterial infected children, using a four-color flow cytometry technique. Results: Our data showed that the percentages and the absolute numbers of monocytes and granulocytes are increased in infected children, when compared to the control group. Similarly, we observed increases in the percentages of B lymphocytes, CD8+ cells, memory T cells (CD4+CD45RO+ and CD8+CD45RO+) and effector lymphocytes (CD4+CD62L? and CD8+CD28?) in infected children compared with the control group. In contrast, naive T cells were decreased in the bacterial infected children relative to the control group. Additionally, we used ELISA assays to identify the pathogen agent in gastrointestinal and respiratory infection. Comparing different types of infection, we found that the children with respiratory bacterial infections had higher percentages of B lymphocytes, and cytotoxic lymphocytes (CD8+CD28-);and the children with gastrointestinal infections had higher percentages of CD3+ lymphocytes and effector cells (CD4+CD62L-). Conclusions The increase in B lymphocytes and CD8+CD28- cells in the children with respiratory infections and the increase of T lymphocytes and CD4+CD62L- cells in the children with gastrointestinal bacterial infections indicate that both cellular and humoral responses coincide, and both responses are necessary for eliminating the pathogen.

Molecular Cloning and Bioinformatics Analysis of TypeⅢSecretion System Effector Protein HY 322 Gene of Vibrio alginolyticus

In this study,Hy322 gene was cloned from Vibrio alginolyticus.The total length of its gene was 969 bp,and it could encode 322 amino acids.The physicochemical properties,protein structure,genetic evolutionary relationship and antigenic characteristics of the effector protein Hy322 of V.alginolyticus HY9901 type Ⅲ secretion system were studied and analyzed by bioinformatics methods and tools.The results showed that Hy322 is an unstable hydrophilic and acidic protein without a transmembrane region and a signal peptide,and secondary structure to α-helix.The evolutionary analysis showed that V.alginolyticus HY9901 and V.harveyi were clustered together,which indicated that the genetic relationship between the two species was closest.HY322 contains a FliN super family conserved domain associated with Flagellar motor switch.Bioinformatics analysis showed that the B-cell preponderant epitopes of Hy322 might be localized in the regions of 32-33,100-102,138-140,215-216,235-238 and 246-249.The 3D structure model of Hy322 subunit was simulated by SWISS-MODEL software and itwas found that the yscQ of Yersinia were similar and the similarity was 42.25%.In this study,the feasibility of Hy322 as a common antigen of Vibrio was verified from the perspective of bioinformatics,which laid the foundation for the next step in vaccine development.

Development of space end-effector with capabilities of misalignment tolerance and soft capture based on tendon-sheath transmission system

The essential requirements of the end-effector of large space manipulator are capabilities of misalignment tolerance and soft capture.According to these requirements,an end-effector prototype combining the tendon-sheath transmission system with steel cable snaring mechanism was manufactured.An analysis method based on the coordinate transformation and the projection of key points of the mechanical interface was proposed,and it was a guideline of the end-effector design.Furthermore,the tendon-sheath transmission system was employed in the capture subassembly to reduce the inertia of the capture mechanism and enlarge the capture space.The capabilities of misalignment tolerance and soft capture were validated through the dynamic simulation in ADAMS software.The results of the capture simulation and experiment show that the end-effector has outstanding capabilities of misalignment tolerance and soft capture.The translation misalignments in radial directions are±100 mm,and angular misalignments about pitch and yaw are±15°.

Development of Chinese large-scale space end-effector

In order to achieve large tolerance capture and high stiffness connection for space payload operations,a Chinese large-scale space end-effector (EER) was developed.Three flexible steel cables were adopted to capture the payload with large capture allowance.Ball screw transmission mechanism and plane shape-constraint four bar linkage mechanism were utilized to connect the payload with high stiffness.The experiments show that capture tolerances in X,Y,Z,Pitch,Yaw,Roll directions are 100 mm,100 mm,120 mm,10.5°,10.5°,12°,respectively.The maximum connection stiffness is 4 800 N·m.The end-effector could meet the requirements for space large tolerance capture and high stiffness connection in the future.