414 research outputs found

    A Downy Mildew Effector Attenuates Salicylic Acid–Triggered Immunity in Arabidopsis by Interacting with the Host Mediator Complex

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    Plants are continually exposed to pathogen attack but usually remain healthy because they can activate defences upon perception of microbes. However, pathogens have evolved to overcome plant immunity by delivering effectors into the plant cell to attenuate defence, resulting in disease. Recent studies suggest that some effectors may manipulate host transcription, but the specific mechanisms by which such effectors promote susceptibility remain unclear. We study the oomycete downy mildew pathogen of Arabidopsis, Hyaloperonospora arabidopsidis (Hpa), and show here that the nuclear-localized effector HaRxL44 interacts with Mediator subunit 19a (MED19a), resulting in the degradation of MED19a in a proteasome-dependent manner. The Mediator complex of ∼25 proteins is broadly conserved in eukaryotes and mediates the interaction between transcriptional regulators and RNA polymerase II. We found MED19a to be a positive regulator of immunity against Hpa. Expression profiling experiments reveal transcriptional changes resembling jasmonic acid/ethylene (JA/ET) signalling in the presence of HaRxL44, and also 3 d after infection with Hpa. Elevated JA/ET signalling is associated with a decrease in salicylic acid (SA)-triggered immunity (SATI) in Arabidopsis plants expressing HaRxL44 and in med19a loss-of-function mutants, whereas SATI is elevated in plants overexpressing MED19a. Using a PR1::GUS reporter, we discovered that Hpa suppresses PR1 expression specifically in cells containing haustoria, into which RxLR effectors are delivered, but not in nonhaustoriated adjacent cells, which show high PR1::GUS expression levels. Thus, HaRxL44 interferes with Mediator function by degrading MED19, shifting the balance of defence transcription from SA-responsive defence to JA/ET-signalling, and enhancing susceptibility to biotrophs by attenuating SA-dependent gene expression

    Probing formation of cargo/importin-α transport complexes in plant cells using a pathogen effector

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    Importin-αs are essential adapter proteins that recruit cytoplasmic proteins destined for active nuclear import to the nuclear transport machinery. Cargo proteins interact with the importin-α armadillo repeat domain via nuclear localization sequences (NLSs), short amino acids motifs enriched in Lys and Arg residues. Plant genomes typically encode several importin-α paralogs that can have both specific and partially redundant functions. Although some cargos are preferentially imported by a distinct importin-α it remains unknown how this specificity is generated and to what extent cargos compete for binding to nuclear transport receptors. Here we report that the effector protein HaRxL106 from the oomycete pathogen Hyaloperonospora arabidopsidis co-opts the host cell's nuclear import machinery. We use HaRxL106 as a probe to determine redundant and specific functions of importin-α paralogs from Arabidopsis thaliana. A crystal structure of the importin-α3/MOS6 armadillo repeat domain suggests that five of the six Arabidopsis importin-αs expressed in rosette leaves have an almost identical NLS-binding site. Comparison of the importin-α binding affinities of HaRxL106 and other cargos in vitro and in plant cells suggests that relatively small affinity differences in vitro affect the rate of transport complex formation in vivo. Our results suggest that cargo affinity for importin-α, sequence variation at the importin-α NLS-binding sites and tissue-specific expression levels of importin-αs determine formation of cargo/importin-α transport complexes in plant cells

    Navigating The Cross-Cultural Challenges of the Philippine Contingent in the United Nations Mission in South Sudan (UNMISS): An Ethnographic Study

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    This ethnographic study investigates into the cross-cultural challenges faced by 23 Filipino Individual Police Officers (IPOs) serving in the United Nations Mission in South Sudan (UNMISS).  This research employs qualitative methods, including structured interviews and participant observation, to explore the impact of cultural differences on performance, communication, and interpersonal relationships within a diverse peacekeeping environment. This research explores three pivotal inquiries:  What shared cultural insights do Filipino IPOs recognize in UNMISS?  What particular obstacles are they encountering?  What effects do these challenges have on their performance? The findings reveal that cultural differences—especially in language, communication styles, and work ethics—resulted in misunderstandings and operational challenges, yet they also fostered growth.  Filipino IPOs showcased remarkable adaptability, patience, and resilience, enhancing collaboration and elevating cultural sensitivity. The research suggests implementing focused strategies, including pre-deployment training, psychological evaluations centered on cultural adaptability, and mentorship initiatives.  This research offers valuable insights into the intricacies of intercultural dynamics within peacekeeping missions. It highlights the critical need to support peacekeepers, thereby boosting their effectiveness and showcasing Filipino cultural values on the international stage

    An RxLR effector from phytophthora infestans prevents re-localisation of two plant NAC transcription factors from the endoplasmic reticulum to the nucleus

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    The plant immune system is activated following the perception of exposed, essential and invariant microbial molecules that are recognised as non-self. A major component of plant immunity is the transcriptional induction of genes involved in a wide array of defence responses. In turn, adapted pathogens deliver effector proteins that act either inside or outside plant cells to manipulate host processes, often through their direct action on plant protein targets. To date, few effectors have been shown to directly manipulate transcriptional regulators of plant defence. Moreover, little is known generally about the modes of action of effectors from filamentous (fungal and oomycete) plant pathogens. We describe an effector, called Pi03192, from the late blight pathogen Phytophthora infestans, which interacts with a pair of host transcription factors at the endoplasmic reticulum (ER) inside plant cells. We show that these transcription factors are released from the ER to enter the nucleus, following pathogen perception, and are important in restricting disease. Pi03192 prevents the plant transcription factors from accumulating in the host nucleus, revealing a novel means of enhancing host susceptibility

    First Measurement of the Transverse Spin Asymmetries of the Deuteron in Semi-Inclusive Deep Inelastic Scattering

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    First measurements of the Collins and Sivers asymmetries of charged hadrons produced in deep-inelastic scattering of muons on a transversely polarized 6-LiD target are presented. The data were taken in 2002 with the COMPASS spectrometer using the muon beam of the CERN SPS at 160 GeV/c. The Collins asymmetry turns out to be compatible with zero, as does the measured Sivers asymmetry within the present statistical errors.Comment: 6 pages, 2 figure

    Securing Public Trust Through Blockchain Integration: The Case of the National Police Clearance System in the Philippines

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    This study examined the use of blockchain technology in the PNP National Police Clearance System (NPCS) to improve public trust. It first assessed trust in the current Relational Database Management System (RDBMS) based on availability, security, immutability, and transparency. Using an explanatory sequential method, the research surveyed 950 applicants and 175 end-users, and conducted 20 key informant interviews. Findings showed that while the public generally trusts the RDBMS (Availability M=3.25; Security M=3.32; Immutability M=3.29; Transparency M=3.22), they also viewed challenges as serious (Availability M=2.95; Security M=2.83; Immutability M=2.79; Transparency M=2.84). Issues included limited access, weak security, data integrity problems, lack of history logs, and poor control mechanisms. Blockchain technology was recommended as an alternative (Availability M=3.18; Security M=3.23; Immutability M=3.27; Transparency M=3.21). Statistical tests revealed significant differences based on awareness, gender, occupation, application purpose, and location. Regression showed a low dependency of blockchain on RDBMS (r²=0.27), but a moderate correlation between the two (0.52, t=16.75). Overall, the study recommends adopting blockchain in the NPCS to strengthen public trust

    Measurement of the Spin Structure of the Deuteron in the DIS Region

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    We present a new measurement of the longitudinal spin asymmetry A_1^d and the spin-dependent structure function g_1^d of the deuteron in the range 1 GeV^2 < Q^2 < 100 GeV^2 and 0.004< x <0.7. The data were obtained by the COMPASS experiment at CERN using a 160 GeV polarised muon beam and a large polarised 6-LiD target. The results are in agreement with those from previous experiments and improve considerably the statistical accuracy in the region 0.004 < x < 0.03.Comment: 10 pages, 6 figures, subm. to PLB, revised: author list, Fig. 4, details adde

    The Impact of Lithium on Brain Function in Bipolar Disorder: An Updated Review of Functional Magnetic Resonance Imaging Studies

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    Lithium remains a gold standard treatment for bipolar disorder (BD), and functional magnetic resonance imaging (fMRI) studies have contributed to clarifying its impact on neural circuitries in affected individuals. However, the specific neurobiological mechanisms through which lithium exerts its effects on brain function are not fully understood. In this review, we aimed to summarize the results of recent fMRI studies evaluating the impact of lithium on brain functional activity and connectivity in patients diagnosed with BD. We performed a literature search of available sources found in the PubMed database reported in English since 2016, when the last available review on this topic was published. Five fMRI studies in resting-state condition and six studies performed during the execution of emotional tasks met the inclusion criteria. Overall, the available evidence supports normalizing effects of lithium on brain activity and connectivity. Most of these studies reported a normalization in prefrontal regions and interconnected areas involved in emotion regulation and processing, regardless of the task employed. Importantly, lithium treatment showed distinct patterns of activity/connectivity changes compared with other treatments. Finally, lithium modulation of neural circuitries was found to be associated with clinical improvement in BD. These results are consistent with the hypothesis that selective abnormalities in neural circuitries supporting emotion processing and regulation improve during lithium treatment in BD. However, the heterogeneity of the examined studies regarding study design, sample selection, and analysis methods might limit the generalizability of the findings and lead to difficulties in comparing the results. Therefore, in future studies, larger cohorts and homogeneous experimental tasks are needed to further corroborate these findings

    Spin asymmetry A_1^d and the spin-dependent structure function g_1^d of the deuteron at low values of x and Q^2

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    We present a precise measurement of the deuteron longitudinal spin asymmetry A_1^d and of the deuteron spin-dependent structure function g_1^d at Q^2 < 1 GeV^2 and 4*10^-5 < x < 2.5*10^-2 based on the data collected by the COMPASS experiment at CERN during the years 2002 and 2003. The statistical precision is tenfold better than that of the previous measurement in this region. The measured A_1^d and g_1^d are found to be consistent with zero in the whole range of x.Comment: 17 pages, 10 figure

    From Theory to Practice: The Effects of Community of Practice Implementation on Out-of-School Youth in the Philippines

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    Communities of Practice (CoP) aims to provide services and skills to partner communities while also establishing links to communicate learned knowledge to broader groups of people. This study identified and analyzed the impact of communities of practice in Barangay Nagtenga, Sta. Cruz, Ilocos Sur. It used a mixed quantitative and qualitative study approach to evaluate the level of satisfaction of the 18 CoP participants as well as their CoP learning and experience. The data demonstrated high levels of CoP satisfaction, notably with resource speakers and the quality of service provided. Participants shared their learning experiences during the CoP, focusing on themes such as knowledge acquisition, skill development, learning transfer to practice, and entrepreneurial management. This study emphasizes the importance of CoPs in empowering marginalized groups and promoting personal and professional development. Recommendations include maintaining and growing CoP initiatives, as well as conducting frequent evaluations to ensure continuous improvement
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