A Novel Signal Transduction Pathway that Modulates <i>rhl</i> Quorum Sensing and Bacterial Virulence in <i>Pseudomonas aeruginosa</i>

The rhl quorum-sensing (QS) system plays critical roles in the pathogenesis of P. aeruginosa. However, the regulatory effects that occur directly upstream of the rhl QS system are poorly understood. Here, we show that deletion of gene encoding for the two-component sensor BfmS leads to the activation of its cognate response regulator BfmR, which in turn directly binds to the promoter and decreases the expression of the rhlR gene that encodes the QS regulator RhlR, causing the inhibition of the rhl QS system. In the absence of bfmS, the Acka-Pta pathway can modulate the regulatory activity of BfmR. In addition, BfmS tunes the expression of 202 genes that comprise 3.6% of the P. aeruginosa genome. We further demonstrate that deletion of bfmS causes substantially reduced virulence in lettuce leaf, reduced cytotoxicity, enhanced invasion, and reduced bacterial survival during acute mouse lung infection. Intriguingly, specific missense mutations, which occur naturally in the bfmS gene in P. aeruginosa cystic fibrosis (CF) isolates such as DK2 strains and RP73 strain, can produce BfmS variants (BfmSL181P, BfmSL181P/E376Q, and BfmSR393H) that no longer repress, but instead activate BfmR. As a result, BfmS variants, but not the wild-type BfmS, inhibit the rhl QS system. This study thus uncovers a previously unexplored signal transduction pathway, BfmS/BfmR/RhlR, for the regulation of rhl QS in P. aeruginosa. We propose that BfmRS TCS may have an important role in the regulation and evolution of P. aeruginosa virulence during chronic infection in CF lungs.</p

Cultivation of novel Atribacterota from oil well provides new insight into their diversity, ecology, and evolution in anoxic, carbon-rich environments

BackgroundThe Atribacterota are widely distributed in the subsurface biosphere. Recently, the first Atribacterota isolate was described and the number of Atribacterota genome sequences retrieved from environmental samples has increased significantly; however, their diversity, physiology, ecology, and evolution remain poorly understood.ResultsWe report the isolation of the second member of Atribacterota, Thermatribacter velox gen. nov., sp. nov., within a new family Thermatribacteraceae fam. nov., and the short-term laboratory cultivation of a member of the JS1 lineage, Phoenicimicrobium oleiphilum HX-OS.bin.34TS, both from a terrestrial oil reservoir. Physiological and metatranscriptomics analyses showed that Thermatribacter velox B11T and Phoenicimicrobium oleiphilum HX-OS.bin.34TS ferment sugars and n-alkanes, respectively, producing H2, CO2, and acetate as common products. Comparative genomics showed that all members of the Atribacterota lack a complete Wood-Ljungdahl Pathway (WLP), but that the Reductive Glycine Pathway (RGP) is widespread, indicating that the RGP, rather than WLP, is a central hub in Atribacterota metabolism. Ancestral character state reconstructions and phylogenetic analyses showed that key genes encoding the RGP (fdhA, fhs, folD, glyA, gcvT, gcvPAB, pdhD) and other central functions were gained independently in the two classes, Atribacteria (OP9) and Phoenicimicrobiia (JS1), after which they were inherited vertically; these genes included fumarate-adding enzymes (faeA; Phoenicimicrobiia only), the CODH/ACS complex (acsABCDE), and diverse hydrogenases (NiFe group 3b, 4b and FeFe group A3, C). Finally, we present genome-resolved community metabolic models showing the central roles of Atribacteria (OP9) and Phoenicimicrobiia (JS1) in acetate- and hydrocarbon-rich environments.ConclusionOur findings expand the knowledge of the diversity, physiology, ecology, and evolution of the phylum Atribacterota. This study is a starting point for promoting more incisive studies of their syntrophic biology and may guide the rational design of strategies to cultivate them in the laboratory. Video Abstract

Diversity and taxonomy of the genus Amanita (Amanitaceae, Agaricales) in the Yanshan Mountains, Northern China

Globally, the species of Amanita are key components of ectomycorrhizal ecosystems. Some of them are widely known as poisonous or edible fungi. Although many new Amanita species from China have been described, the species diversity of Yanshan Mountains remains unknown. We here describe three new species, namely, A. borealis sp. nov. (Sect. Amanita), A. brunneola sp. nov. (Sect. Caesareae), and A. yanshanensis sp. nov. (Sect. Validae), based on morphological observations and molecular phylogenetic analyses. In addition, nine known species, namely, A. caesareoides (Sect. Caesareae), A. chiui (Sect. Vaginatae), A. muscaria (Sect. Amanita), A. oberwinklerana (Sect. Roanokenses), A. ovalispora (Sect. Vaginatae), A. subglobosa (Sect. Amanita), A. subjunquillea (Sect. phalloideae), A. vaginata var. vaginata (Sect. Vaginatae), and A. virosa (Sect. phalloideae), were reported from Yanshan Mountains for the first time. Our results emphasize that China has a high diversity of Amanita species and that additional studies are required to understand the exact species number. These findings play a crucial role in Amanita toxin research and ecological conservation. This study investigated the areas where Amanita species-related research is lacking. The study also attempted to better understand Amanita distribution and thus contribute to related research. This study enriches the species diversity of Amanita in Yanshan Mountains and offers additional data supporting the macrofungal systematics, toxin research, and diversity and ecological studies of Amanita in future studies

Src-IL-18 signaling regulates the secretion of atrial natriuretic factor in hypoxic beating rat atria

Background: Interleukin (IL)-18 is produced mainly in the heart and can be associated with the developmentof cardiac hypertrophy that leads to cardiac dysfunction. However, the effects of hypoxia onIL-18 expression and atrial natriuretic factor (ANF) secretion remain largely unknown.Aim: The aim of this study was to assess the effect of hypoxia on IL-18 production and its role in ANFsecretion by using an isolated perfused beating rat atrial model.Methods: The level of ANF in the perfusates was determined by radioimmunoassay, and the proteinlevels of Src, IL-18 and its receptors (IL-18-Rα and IL-18-Rβ), Rho guanine nucleotide exchange factor(RhoGEF) and RhoA, activating transcription factor 3 (ATF3), T cell factor (TCF) 3 and 4, and lymphoidenhancer factor (LEF) 1 in atrial tissue samples were detected by Western blotting.Results: Hypoxia significantly upregulated the expression of the non-receptor tyrosine kinase Src, andthis effect was blocked by endothelin-1 receptor type A (BQ123) and type B (BQ788) antagonists. Hypoxiaalso enhanced the expression of RhoGEF and RhoA concomitantly with the upregulation ofIL-18, IL-18-Rα and IL-18-Rβ. The hypoxia-induced RhoGEF and RhoA were abolished by Src inhibitor1 (SrcI), and the protein levels of IL-18 and its two receptors were also blocked by SrcI. Moreover, thehypoxia-induced expression levels of ATF3, TCF3, TCF4 and LEF1 were repealed by IL-18 binding protein,and the hypoxia-promoted secretion of ANF was also obviously attenuated by this binding protein.Conclusions: These findings imply that Src-IL-18 signaling is involved in the release of ANF in hypoxicbeating rat atria

Effects of Organophosphate-Degrading Bacteria on the Plant Biomass, Active Medicinal Components, and Soil Phosphorus Levels of Paris polyphylla var. yunnanensis

Paris polyphylla var. yunnanensis, a medicinal plant that originated in Yunnan (China), has been over-harvested in the wild population, resulting in its artificial cultivation. Given the negative environmental impacts of the excessive use of phosphorus (P) fertilization, the application of organophosphate-degrading bacteria (OPDB) is a sustainable approach for improving the P use efficiency in Paris polyphylla var. yunnanensis production. The present work aimed to analyze the effects of three organic phosphate-solubilizing bacteria of Bacillus on the yield and quality of P. polyphylla var. yunnanensis and the P concentrations in the soil. All the inoculation treatments distinctly increased the rhizome biomass, steroidal, and total saponin concentrations of the rhizomes and the Olsen-P and organic P in the soil. The highest growth rate of rhizomes biomass, steroidal saponins, available phosphorus, and total phosphorus content was seen in the S7 group, which was inoculated with all three OPDB strains, showing increases of 134.58%, 132.56%, 51.64%, and 17.19%, respectively. The highest total saponin content was found in the group inoculated with B. mycoides and B. wiedmannii, which increased by 33.68%. Moreover, the highest organic P content was seen in the group inoculated with B. wiedmannii and B. proteolyticus, which increased by 96.20%. In addition, the rhizome biomass was significantly positively correlated with the saponin concentration, together with the positive correlation between the Olsen-P and organic P and total P. It is concluded that inoculation with organophosphate-degrading bacteria improved the biomass and medicinal ingredients of the rhizome in P. polyphylla var. yunnanensis, coupled with increased soil P fertility, with a mixture of the three bacteria performing best

Electroacupuncture pretreatment exhibits anti-depressive effects by regulating hippocampal proteomics in rats with chronic restraint stress

The clinical effect of electroacupuncture on depression is widely recognized. However, the signal transduction pathways and target proteins involved remain unclear. In the present study, rat models of chronic restraint stress were used to explore the mechanism by which electroacupuncture alleviates depression. Rats were randomly divided into control, model, and electroacupuncture groups. Chronic restraint stress was induced in the model and electroacupuncture groups by restraining rats for 28 days. In the electroacupuncture group, electroacupuncture pretreatment at Baihui (GV20) and Yintang (GV29) acupoints was performed daily (1 mA, 2 Hz, discontinuous wave, 20 minutes) prior to restraint for 28 days. Open field tests and body weight measurements were carried out to evaluate the depressive symptoms at specific time points. On day 28, the crossing number, rearing number, and body weights of the model group were significantly lower than those in the control group. Behavior test results indicated that rat models of depressive-like symptoms were successfully established by chronic restraint stress combined with solitary raising. On day 28, an isobaric tag for a relative and absolute quantitation-based quantitative proteomic approach was performed to identify differentially expressed proteins in hippocampal samples obtained from the model and electroacupuncture groups. The potential function of these differential proteins was predicted through the use of the Cluster of Orthologous Groups of proteins (COG) database. Twenty-seven differential proteins (uncharacteristic proteins expected) were selected from the model and electroacupuncture groups. In addition to unknown protein functions, COG are mainly concentrated in general prediction function, mechanism of signal transduction, amino acid transport and metabolism groups. This suggests that electroacupuncture improved depressive-like symptoms by regulating differential proteins, and most of these related proteins exist in nerve cells

Synthesis and Antiviral Activity of N-Phenylbenzamide Derivatives, a Novel Class of Enterovirus 71 Inhibitors

A series of novel N-phenylbenzamide derivatives were synthesized and their anti-EV 71 activities were assayed in vitro. Among the compounds tested, 3-amino-N-(4-bromophenyl)-4-methoxybenzamide (1e) was active against the EV 71 strains tested at low micromolar concentrations, with IC50 values ranging from 5.7 ± 0.8–12 ± 1.2 μM, and its cytotoxicity to Vero cells (TC50 = 620 ± 0.0 μM) was far lower than that of pirodavir (TC50 = 31 ± 2.2 μM). Based on these results, compound 1e is a promising lead compound for the development of anti-EV 71 drugs