Helicobacter pylori-downregulated tumor necrosis factor receptor-associated protein 1 mediates apoptosis of human gastric epithelial cells

Heat shock proteins (HSPs) are crucial proteins in maintaining the homeostasis of human gastric epithelial cells. Tumor necrosis factor receptor-associated protein 1 (TRAP1), a member of the HSP90 family, has been shown to be involved in various crucial physiological processes, particularly against apoptosis. However, the regulation and function of TRAP1 in Helicobacter pylori infection is still unknown. Here, we found that TRAP1 expression was downregulated on human gastric epithelial cells during H. pylori infection by real-time polymerase chain reaction (PCR) and western blot analysis. Through virulence factors mutant H. pylori strains infection and inhibitors screening, we found that H. pylori vacuolating cytotoxin A ( vacA), but not cytotoxin-associated gene A ( cagA) protein, induced human gastric epithelial cells to downregulate TRAP1 via P38MAPK pathway by real-time PCR and western blot analysis. Furthermore, downregulation of TRAP1 with lentivirus carrying TRAP1 short hairpin RNA constructs impairs mitochondrial function, and increases apoptosis of gastric epithelial cells. The results indicate that H. pylori vacA downregulated TRAP1 is involved in the regulation of gastric epithelial cell apoptosis.     

Stability of Mixed-Strategy-Based Iterative Logit Quantal Response Dynamics in Game Theory

Using the Logit quantal response form as the response function in each step, the original definition of static quantal response equilibrium (QRE) is extended into an iterative evolution process. QREs remain as the fixed points of the dynamic process. However, depending on whether such fixed points are the long-term solutions of the dynamic process, they can be classified into stable (SQREs) and unstable (USQREs) equilibriums. This extension resembles the extension from static Nash equilibriums (NEs) to evolutionary stable solutions in the framework of evolutionary game theory. The relation between SQREs and other solution concepts of games, including NEs and QREs, is discussed. Using experimental data from other published papers, we perform a preliminary comparison between SQREs, NEs, QREs and the observed behavioral outcomes of those experiments. For certain games, we determine that SQREs have better predictive power than QREs and NEs.     

Effect of transplantation route on stem cell migration to fibrotic liver of rats via cellular magnetic resonance imaging

Background aimsAssessing mesenchymal stromal cells (MSCs) after grafting is essential for understanding their migration and differentiation processes. The present study sought to evaluate via cellular magnetic resonance imaging (MRI) if transplantation route may have an effect on MSCs engrafting to fibrotic liver of rats.MethodsRat MSCs were prepared, labeled with superparamagnetic iron oxide and scanned with MRI. Labeled MSCs were transplanted via the portal vein or vena caudalis to rats with hepatic fibrosis. MRI was performed in vitro before and after transplantation. Histologic examination was performed. MRI scan and imaging parameter optimization in vitro and migration under in vivo conditions were demonstrated.ResultsStrong MRI susceptibility effects could be found on gradient echo-weighted, or T21-weighted, imaging sequences from 24 h after labeling to passage 4 of labeled MSCs in vitro. In vivo, MRI findings of the portal vein group indicated lower signal in liver on single shot fast spin echo-weighted, or T2-weighted, imaging and T21-weighted imaging sequences. The low liver MRI signal increased gradually from 0–3 h and decreased gradually from 3 h to 14 days post-transplantation. The distribution pattern of labeled MSCs in liver histologic sections was identical to that of MRI signal. It was difficult to find MSCs in tissues near the portal area on day 14 after transplantation; labeled MSCs appeared in fibrous tuberculum at the edge of the liver. No MRI signal change and a positive histologic examination were observed in the vena caudalis group.ConclusionsThe portal vein route seemed to be more beneficial than the vena caudalis on MSC migration to fibrotic liver of rats via MRI.     

峨眉山八角莲属植物的生态学与生物学特性研究

本文对蛾眉山八角莲属植物的种类分布、生境和生物学特性进行了研究,结果表明,①蛾眉山八角莲属植物5种1变种,原始及变异类型分布集中;②种间垂直替代现象明显,对于阴湿环境及肥沃、酸性、多砾质土壤环境反应出一定程度的共同要求;③不同种类在生长节律、特性、花粉育性、花粉发芽条件以及自然繁殖能力等方面存在一定差别;④人工根插繁殖可提高本属植物的繁殖系数。     

Observational constraints reduce model spread but not uncertainty in global wetland methane emission estimates

The recent rise in atmospheric methane (CH₄) concentrations accelerates climate change and offsets mitigation efforts. Although wetlands are the largest natural CH₄ source, estimates of global wetland CH₄ emissions vary widely among approaches taken by bottom-up (BU) process-based biogeochemical models and top-down (TD) atmospheric inversion methods. Here, we integrate in situ measurements, multi-model ensembles, and a machine learning upscaling product into the International Land Model Benchmarking system to examine the relationship between wetland CH₄ emission estimates and model performance. We find that using better-performing models identified by observational constraints reduces the spread of wetland CH₄ emission estimates by 62% and 39% for BU- and TD-based approaches, respectively. However, global BU and TD CH₄ emission estimate discrepancies increased by about 15% (from 31 to 36 TgCH₄ year⁻¹) when the top 20% models were used, although we consider this result moderately uncertain given the unevenly distributed global observations. Our analyses demonstrate that model performance ranking is subject to benchmark selection due to large inter-site variability, highlighting the importance of expanding coverage of benchmark sites to diverse environmental conditions. We encourage future development of wetland CH₄ models to move beyond static benchmarking and focus on evaluating site-specific and ecosystem-specific variabilities inferred from observations.     

A bacterial type III effector targets plant vesicle-associated membrane proteins

The soilborne bacterial pathogen Ralstonia solanacearum is one of the most destructive plant pathogens worldwide, and its infection process involves the manipulation of numerous plant cellular functions. In this work, we found that the R. solanacearum effector protein RipD partially suppressed different levels of plant immunity triggered by R. solanacearum elicitors, including specific responses triggered by pathogen-associated molecular patterns and secreted effectors. RipD localized in different subcellular compartments in plant cells, including vesicles, and its vesicular localization was enriched in cells undergoing R. solanacearum infection, suggesting that this specific localization may be particularly relevant during infection. Among RipD-interacting proteins, we identified plant vesicle-associated membrane proteins (VAMPs). We also found that overexpression of Arabidopsis thaliana VAMP721 and VAMP722 in Nicotiana benthamiana leaves promoted resistance to R. solanacearum, and this was abolished by the simultaneous expression of RipD, suggesting that RipD targets VAMPs to contribute to R. solanacearum virulence. Among proteins secreted in VAMP721/722-containing vesicles, CCOAOMT1 is an enzyme required for lignin biosynthesis, and mutation of CCOAOMT1 enhanced plant susceptibility to R. solanacearum. Altogether our results reveal the contribution of VAMPs to plant resistance against R. solanacearum and their targeting by a bacterial effector as a pathogen virulence strategy.