Reactive oxygen species play a role in P2X7 receptor-mediated IL-6 production in spinal astrocytes

Purinergic Signalling - Astrocytes mediate a remarkable variety of cellular functions, including gliotransmitter release. Under pathological conditions, high concentrations of the purinergic...     

Emperipolesis mediated by CD8+ T cells correlates with biliary epithelia cell injury in primary biliary cholangitis

Primary biliary cholangitis (PBC) is an autoimmune disease characterized by chronic destruction of the bile ducts. A major unanswered question regarding the pathogenesis of PBC is the precise mechanisms of small bile duct injury. Emperipolesis is one of cell‐in‐cell structures that is a potential histological hallmark associated with chronic hepatitis B. This study aimed to clarify the pathogenesis and characteristics of emperipolesis in PBC liver injury. Sixty‐six PBC patients, diagnosed by liver biopsy combined with laboratory test, were divided into early‐stage PBC (stages I and II, n = 39) and late‐stage PBC (stages III and IV, n = 27). Emperipolesis was measured in liver sections stained with haematoxylin‐eosin. The expressions of CK19, CD3, CD4, CD8, CD20, Ki67 and apoptosis of BECs were evaluated by immunohistochemistry or immunofluorescence double labelling. Emperipolesis was observed in 62.1% of patients with PBC, and BECs were predominantly host cells. The number of infiltrating CD3⁺ and CD8⁺ T cells correlated with the advancement of emperipolesis (R² = 0.318, P < .001; R² = 0.060, P < .05). The cell numbers of TUNEL‐positive BECs and double staining for CK19 and Ki67 showed a significant positive correlation with emperipolesis degree (R² = 0.236, P < .001; R² = 0.267, P < .001). We conclude that emperipolesis mediated by CD8⁺ T cells appears to be relevant to apoptosis of BEC and thus may aggravate the further injury of interlobular bile ducts.     

Characterization of non-canonical G beta-like protein FvGbb2 and its relationship with heterotrimeric G proteins in Fusarium verticillioides

Fusarium verticillioides is a fungal pathogen that is responsible for maize ear rot and stalk rot diseases worldwide. The fungus also produces carcinogenic mycotoxins, fumonisins on infested maize. Unfortunately, we still lack clear understanding of how the pathogen responds to host and environmental stimuli to trigger fumonisin biosynthesis. The heterotrimeric G protein complex, consisting of canonical Gα, Gβ and Gγ subunits, is involved in transducing signals from external stimuli to regulate downstream signal transduction pathways. Previously, we demonstrated that Gβ protein FvGbb1 directly impacts fumonisin regulation but not other physiological aspects in F. verticillioides. In this study, we identified and characterized a RACK1 (Receptor for Activated C Kinase 1) homolog FvGbb2 as a putative Gβ-like protein in F. verticillioides. The mutant exhibited severe defects not only in fumonisin biosynthesis but also vegetative growth and conidiation. FvGbb2 was positively associated with carbon source utilization and stress agents but negatively regulated general amino acid control. While FvGbb2 does not interact with canonical G protein subunits, it may associate with diverse proteins in the cytoplasm to regulate vegetative growth, virulence, fumonisin biosynthesis and stress response in F. verticillioides.     

Agrobacterium tumefaciens ferritins play an important role in full virulence through regulating iron homeostasis and oxidative stress survival

Ferritins are a large family of iron storage proteins, which are used by bacteria and other organisms to avoid iron toxicity and as a safe iron source in the cytosol. Agrobacterium tumefaciens, a phytopathogen, has two ferritin-encoding genes: atu2771 and atu2477. Atu2771 is annotated as a Bfr-encoding gene (Bacterioferritin, Bfr) and atu2477 as a Dps-encoding gene (D NA binding p rotein from s tarved cells, Dps). Three deletion mutants (Δbfr, Δdps, and bfr-dps double-deletion mutant ΔbdF) of these two ferritin-encoding genes were constructed to investigate the effects of ferritin deficiency on the iron homeostasis, oxidative stress resistance, and pathogenicity of A. tumefaciens. Deficiency of two ferritins affects the growth of A. tumefaciens under iron starvation and excess. When supplied with moderate iron, the growth of A. tumefaciens is not affected by the deficiency of ferritin. Deficiency of ferritin significantly reduces iron accumulation in the cells of A. tumefaciens, but the effect of Bfr deficiency on iron accumulation is severer than Dps deficiency and the double mutant ΔbdF has the least intracellular iron content. All three ferritin-deficient mutants showed a decreased tolerance to 3 mM H₂O₂ in comparison with the wild type. The tumour induced by each of three ferritin-deficient mutants is less than that of the wild type. Complementation reversed the effects of ferritin deficiency on the growth, iron homeostasis, oxidative stress resistance, and tumorigenicity of A. tumefaciens. Therefore, ferritin plays an important role in the pathogenesis of A. tumefaciens through regulating iron homeostasis and oxidative stress survival.     

The essential effector SCRE1 in Ustilaginoidea virens suppresses rice immunity via a small peptide region

The biotrophic fungal pathogen Ustilaginoidea virens causes rice false smut, a newly emerging plant disease that has become epidemic worldwide in recent years. The U. virens genome encodes many putative effector proteins that, based on the study of other pathosystems, could play an essential role in fungal virulence. However, few studies have been reported on virulence functions of individual U. virens effectors. Here, we report our identification and characterization of the secreted cysteine-rich protein SCRE1, which is an essential virulence effector in U. virens. When SCRE1 was heterologously expressed in Magnaporthe oryzae, the protein was secreted and translocated into plant cells during infection. SCRE1 suppresses the immunity-associated hypersensitive response in the nonhost plant Nicotiana benthamiana. Induced expression of SCRE1 in rice also inhibits pattern-triggered immunity and enhances disease susceptibility to rice bacterial and fungal pathogens. The immunosuppressive activity is localized to a small peptide region that contains an important ‘cysteine-proline-alanine-arginine-serine’ motif. Furthermore, the scre1 knockout mutant generated using the CRISPR/Cas9 system is attenuated in U. virens virulence to rice, which is greatly complemented by the full-length SCRE1 gene. Collectively, this study indicates that the effector SCRE1 is able to inhibit host immunity and is required for full virulence of U. virens.     

A chemically triggered transition from conflict to cooperation in burying beetles

Although interspecific competition has long been recognised as a major driver of trait divergence and adaptive evolution, relatively little effort has focused on how it influences the evolution of intraspecific cooperation. Here we identify the mechanism by which the perceived pressure of interspecific competition influences the transition from intraspecific conflict to cooperation in a facultative cooperatively breeding species, the Asian burying beetle Nicrophorus nepalensis. We not only found that beetles are more cooperative at carcasses when blowfly maggots have begun to digest the tissue, but that this social cooperation appears to be triggered by a single chemical cue – dimethyl disulfide (DMDS) – emitted from carcasses consumed by blowflies, but not from control carcasses lacking blowflies. Our results provide experimental evidence that interspecific competition promotes the transition from intraspecific conflict to cooperation in N. nepalensis via a surprisingly simple social chemical cue that is a reliable indicator of resource competition between species.     

石墨烯对植物的生理毒性效应研究进展

石墨烯是当前研究最热的碳纳米材料,具有独特的理化特性,在各领域广泛应用。随着石墨烯生产和使用量的不断增大,其不可避免地进入到环境中,给生态环境和人类健康带来风险。阐明石墨烯的潜在毒性效应及其作用机制对于客观评价石墨烯的生态环境健康风险具有重要意义。迄今为止,已有诸多研究报道了石墨烯的植物生理毒理效应。研究表明,石墨烯对植物的生理学响应及其生理变化过程存在影响,涉及萌芽、幼苗生长、氧化应激、光合特性、植物激素和代谢过程等,且多呈浓度效应。今后亟需构建一套被广泛认可的植物石墨烯毒性评价体系,为石墨烯的安全生产和使用提供指导。