Pathogen recognition and the triggering of host innate immune system are critical to understanding pathogen-host interaction. Cellular surveillance systems have been identified as an important ...strategy for the identification of microbial infection. In the present study, using Bacillus thuringiensis-Caenorhabditis elegans as a model, we found an approach for surveillance systems to sense pathogens. We report that Bacillus thuringiensis Cry5Ba, a typical pore-forming toxin, caused mitochondrial damage and energy imbalance by triggering potassium ion leakage, instead of directly targeting mitochondria. Interestingly, we find C. elegans can monitor intracellular energy status to trigger innate immune responses via AMP-activated protein kinase (AMPK), secreting multiple effectors to defend against pathogenic attacks. Our study indicates that the imbalance of energy status is a prevalent side effect of pathogen infection. Furthermore, the AMPK-dependent surveillance system may serve as a practicable strategy for the host to recognize and defense against pathogens.
Abstract
OBJECTIVES
Acute lung injury caused by cardiopulmonary bypass (CPB) is characterized by massive neutrophil migration to the lungs. Neutrophil migration may be closely related to stromal ...cell-derived factor 1 (SDF-1)/C-X-C chemokine receptor Type 4 (CXCR4) axis activation, which plays an essential role in modulating the trafficking of neutrophils. We investigated the changes in the expression of SDF-1/CXCR4 axis components before and after CPB as well as the role of the axis in driving the migration of neutrophils in patients with congenital heart disease.
METHODS
Fifteen children undergoing elective open-heart surgery under CPB (CPB group) and 15 children undergoing minimally invasive ultrasound-guided closure of a ventricular septal defect (control group) were enrolled in this non-randomized clinical trial. Neutrophil CXCR4 expression was evaluated using quantitative reverse transcription polymerase chain reaction and flow cytometry. An enzyme-linked immunosorbent assay was used to measure plasma SDF-1 levels. The migration characteristics of neutrophils under 8 different combinations designated A–H were assayed with and without a specific CXCR4 antagonist, AMD3100, to evaluate the functional significance of the SDF-1/CXCR4 axis.
RESULTS
Both CXCR4 gene and protein expressions were elevated in the CPB group compared with the control group after CPB (0.81 ± 0.55 vs 1.76 ± 1.32; P < 0.05, 1.96 ± 0.86 vs 2.65 ± 0.79; P < 0.05), and plasma SDF-1 levels were also increased in the former compared with the latter (197.84 ± 19.96 pg/ml vs 539.13 ± 99.83 pg/ml; P < 0.05). The in vitro experiments showed that plasma isolated post-CPB exhibited the strongest chemotactic effect on neutrophils. The CPB group showed a higher chemotaxis index, which serves as a marker for the effects of plasma on neutrophils, than that for the control group after CPB (37.38 ± 9.39 vs 13.61 ± 2.59; P < 0.05). In addition, the CXCR4 antagonist AMD3100 significantly abrogated the increase in neutrophil migration in the CPB group.
CONCLUSIONS
Exposure to CPB, which activates the SDF-1/CXCR4 axis, using an antagonist to prevent neutrophil trafficking, may be a beneficial therapy for the related complications.
Plant-parasitic nematodes were found in 4 of the 12 clades of phylum Nematoda. These nematodes in different clades may have originated independently from their free-living fungivorous ancestors. ...However, the exact evolutionary process of these parasites is unclear. Here, we sequenced the genome sequence of a migratory plant nematode, Ditylenchus destructor. We performed comparative genomics among the free-living nematode, Caenorhabditis elegans and all the plant nematodes with genome sequences available. We found that, compared with C. elegans, the core developmental control processes underwent heavy reduction, though most signal transduction pathways were conserved. We also found D. destructor contained more homologies of the key genes in the above processes than the other plant nematodes. We suggest that Ditylenchus spp. may be an intermediate evolutionary history stage from free-living nematodes that feed on fungi to obligate plantparasitic nematodes. Based on the facts that D. destructor can feed on fungi and has a relatively short life cycle, and that it has similar features to both C. elegans and sedentary plant-parasitic nematodes from clade 12, we propose it as a new model to study the biology, biocontrol of plant nematodes and the interaction between nematodes and plants.
Cell death plays an important role in host-pathogen interactions. Crystal proteins (toxins) are essential components of Bacillus thuringiensis (Bt) biological pesticides because of their specific ...toxicity against insects and nematodes. However, the mode of action by which crystal toxins to induce cell death is not completely understood. Here we show that crystal toxin triggers cell death by necrosis signaling pathway using crystal toxin Cry6Aa-Caenorhabditis elegans toxin-host interaction system, which involves an increase in concentrations of cytoplasmic calcium, lysosomal lyses, uptake of propidium iodide, and burst of death fluorescence. We find that a deficiency in the necrosis pathway confers tolerance to Cry6Aa toxin. Intriguingly, the necrosis pathway is specifically triggered by Cry6Aa, not by Cry5Ba, whose amino acid sequence is different from that of Cry6Aa. Furthermore, Cry6Aa-induced necrosis pathway requires aspartic protease (ASP-1). In addition, ASP-1 protects Cry6Aa from over-degradation in C. elegans. This is the first demonstration that deficiency in necrosis pathway confers tolerance to Bt crystal protein, and that Cry6A triggers necrosis represents a newly added necrosis paradigm in the C. elegans. Understanding this model could lead to new strategies for nematode control.
A new type of oil pipe inspection robot will be presented and the structure and function movement of which will be described in this paper, what's more, the obstacle avoidance control system of the ...robot will be researched in the paper according to the technological problems of the inspection robot in oil pipeline. The results of the simulation experiment in VC++ environment show that the obstacle avoidance control technology has good real-time, robustness and flexibility and the disadvantage that the environment model is difficult to be established in traditional strategy of obstacle avoidance control can be overcome with the strategy of avoiding obstruction of fuzzy control.
Pipeline robot is a research hotspot in pipeline industry, as the same as research and application in petroleum pipeline .Because that the condition is special in downhole, the performance of ...downhole crawling robot is different from general pipeline robot. This paper introduces downhole crawling robot, key technology on driving unit Downhole crawling robot can adapt to holes of different diameter by improved driving unit, and add bidirectional spring jar to improving the working properties of downhole crawling robot .Finally combining the development survey of petroleum industry and related technology, giving summary of research and prospect about downhole crawling robot.
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