Salmonella Enteritidis antitoxin DinJ inhibits NLRP3-dependent canonical inflammasome activation in macrophages

The inflammasome is a pivotal component of the innate immune system, acting as a multiprotein complex that plays an essential role in detecting and responding to microbial infections. Salmonella Enteritidis have evolved multiple mechanisms to regulate inflammasome activation and evade host immune system clearance. Through screening S. Enteritidis C50336ΔfliC transposon mutant library, we found that the insertion mutant of dinJ increased inflammasome activation. In this study, we demonstrated the genetic connection between the antitoxin DinJ and the toxin YafQ in S. Enteritidis, confirming their co-transcription. The deletion mutant ΔfliCΔdinJ increased cell death and IL-1β secretion in J774A.1 cells. Western blotting analysis further showed elevated cleaved Caspase-1 product (p10 subunits) and IL-1β secretion in cells infected with ΔfliCΔdinJ compared to cells infected with ΔfliC. DinJ was found to inhibit canonical inflammasome activation using primary bone marrow-derived macrophages (BMDMs) from Casp-/- C57BL/6 mice. Furthermore, DinJ specifically inhibited NLRP3 inflammasome activation, as demonstrated in BMDMs from Nlrp3-/- and Nlrc4-/- mice. Fluorescence resonance energy transfer (FRET) experiments confirmed the translocation of DinJ into host cells during infection. Finally, we revealed that DinJ could inhibit the secretion of IL-1β and IL-18 in vivo, contributing to S. Enteritidis evading host immune clearance. In summary, our findings provide insights into the role of DinJ in modulating the inflammasome response during S. Enteritidis infection, highlighting its impact on inhibiting inflammasome activation and immune evasion.

Retrospective analysis of preoperative application of triple-modal pre-rehabilitation on postoperative recovery of colorectal cancer patients

PURPOSE

To retrospectively analyze the difference between triple-modal pre-rehabilitation and common treatment in patients with colorectal cancer (CRC).

METHODS

A total of 145 patients with CRC diagnosed by pathology and admitted to our hospital for surgery between June 2020 and June 2022 were included in the study. All patients were divided into two groups: the triple-modal pre-rehabilitation group (pre-rehabilitation group) and the common treatment group. The triple-modal pre-rehabilitation strategy included exercise (3-5 times per week, with each session lasting more than 50 min), nutritional support, and psychological support. The study was designed to assess the potential of the pre-rehabilitation intervention to accelerate postoperative recovery by assessing the 6-min walk test, nutritional indicators, and HADS score before and after surgery.

RESULTS

The pre-rehabilitation intervention did not reduce the duration of initial postoperative recovery or the incidence of postoperative complications, but it did increase the patients' exercise capacity (as determined by the 6-min walk test), with the pre-rehabilitation group performing significantly better than the common group (433.0 (105.0) vs. 389.0 (103.5), P < 0.001). The study also found that triple-modal pre-rehabilitation was beneficial for the early recovery of nutritional status in surgical patients and improved anxiety and depression in patients after surgery, especially in those who had not received neoadjuvant therapy.

CONCLUSION

The triple-modal pre-rehabilitation strategy is of significant importance for reducing stress and improving the functional reserve of patients with colorectal cancer (CRC) during the perioperative period. The results of our study provide further support for the integration of the triple-modal pre-rehabilitation strategy into the treatment and care of CRC patients.

Melatonin, a phytohormone for enhancing the accumulation of high-value metabolites and stress tolerance in microalgae: Applications, mechanisms, and challenges

High-value metabolites, such as carotenoids, lipids, and proteins, are synthesized by microalgae and find applications in various fields, including food, health supplements, and cosmetics. However, the potential of the microalgal industry to serve these sectors is constrained by low productivity and high energy consumption. Environmental stressors can not only stimulate the accumulation of secondary metabolites in microalgae but also induce oxidative stress, suppressing cell growth and activity, thereby resulting in a decrease in overall productivity. Using melatonin (MT) under stressful conditions is an effective approach to enhance the productivity of microalgal metabolites. This review underscores the role of MT in promoting the accumulation of high-value metabolites and enhancing stress resistance in microalgae under stressful and wastewater conditions. It discusses the underlying mechanisms whereby MT enhances metabolite synthesis and improves stress resistance. The review also offers new perspectives on utilizing MT to improve microalgal productivity and stress resistance in challenging environments.

Microevolution of Salmonella 4,[5],12:i:- derived from Salmonella enterica serovar Typhimurium through complicated transpositions

Salmonella enterica subsp. enterica serovar 4,[5],12:i:- (Salmonella 4,[5],12:i:-), derived from S. Typhimurium, has become the dominant serotype causing human salmonellosis. In this study, we define the genetic mechanism of the generation of Salmonella 4,[5],12:i:- from S. Typhimurium through complicated transpositions and demonstrate that Salmonella 4,[5],12:i:- displays more efficient colonization and survival abilities in mice than its parent S. Typhimurium strain. We identified intermediate strains carrying both resistance regions (RRs) and the fljAB operon for the generation of Salmonella 4,[5],12:i:-. The insertion of RR3 into the chromosomal hin-iroB site of S. Typhimurium produced RR3-S. Typhimurium as a primary intermediate. Salmonella 4,[5],12:i:- was then produced by replacing the fljAB operon and/or its flanking sequences through intramolecular transpositions mediated by IS26 and/or IS1R elements in RR3-S. Typhimurium, which was further confirmed both in vitro and in vivo. Overall, we demonstrate the molecular mechanism underlying the origin, generation, and advantage of RRs-Salmonella 4,[5],12:i:- from S. Typhimurium.

Comprehensive understanding of the regulatory mechanism by which selenium nanoparticles boost CO2 fixation and cadmium tolerance in lipid-producing green algae under recycled medium

Recycled medium plus cadmium is a promising technique for reducing the cultivation cost and enhancing the yield of microalgae lipids. However, oxidative stress and cadmium toxicity significantly hinder the resulting photosynthetic efficiency, cell growth and cell activity. Herein, selenium nanoparticles (SeNPs) were used to increase the total biomass, biolipid productivity, and tolerance to cadmium. Wide-ranging analyses of photosynthesis, energy yield, fatty acid profiles, cellular ultrastructure, and oxidative stress biomarkers were conducted to examine the function of SeNPs in CO2 fixation and cadmium resistance in Ankistrodesmus sp. EHY. The application of 15 μM cadmium and 2 mg L-1 SeNPs further enhanced the algal biomass productivity and lipid productivity to 500.64 mg L-1 d-1 and 301.14 mg L-1 d-1, respectively. Moreover, the rates of CO2 fixation, chlorophyll synthesis and total nitrogen removal were similarly increased by the application of SeNPs. Exogenous SeNPs strengthened cell growth and cadmium tolerance by upregulating photosynthesis, the TCA cycle and the antioxidant system, reducing the uptake and translocation of cadmium, and decreasing the levels of reactive oxidative stress (ROS), extracellular polymeric substances (EPSs) and cellular Cd2+ level in EHY under recycled medium and cadmium stress conditions. Additionally, a maximum energy yield of 127.40 KJ L-1 and a lipid content of 60.15% were achieved in the presence of both SeNPs and cadmium stress. This study may inspire the efficient disposal of recycled medium and biolipid production while also filling the knowledge gaps regarding the mechanisms of SeNP functions in carbon fixation and cadmium tolerance in microalgae.

Efficient screening of adsorbed receptors for Salmonella phage LP31 and identification of receptor-binding protein

The adsorption process is the first step in the lifecycle of phages and plays a decisive role in the entire infection process. Identifying the adsorption mechanism of phages not only makes phage therapy more precise and efficient but also enables the exploration of other potential applications and modifications of phages. Phage LP31 can lyse multiple Salmonella serotypes, efficiently clearing biofilms formed by Salmonella enterica serovar Enteritidis (S. Enteritidis) and significantly reducing the concentration of S. Enteritidis in chicken feces. Therefore, LP31 has great potential for many practical applications. In this study, we established an efficient screening method for phage infection-related genes and identified a total of 10 genes related to the adsorption process of phage LP31. After the construction of strain C50041ΔrfaL 58-358, it was found that the knockout strain had a rough phenotype as an O-antigen-deficient strain. Adsorption rate and transmission electron microscopy experiments showed that the receptor for phage LP31 was the O9 antigen of S. Enteritidis. Homology comparison and adsorption experiments confirmed that the tail fiber protein Lp35 of phage LP31 participated in the adsorption process as a receptor-binding protein. IMPORTANCE A full understanding of the interaction between phages and their receptors can help with the development of phage-related products. Phages like LP31 with the tail fiber protein Lp35, or a closely related protein, have been reported to effectively recognize and infect multiple Salmonella serotypes. However, the role of these proteins in phage infection has not been previously described. In this study, we established an efficient screening method to detect phage adsorption to host receptors. We found that phage LP31 can utilize its tail fiber protein Lp35 to adsorb to the O9 antigen of S. Enteritidis, initiating the infection process. This study provides a great model system for further studies of how a phage-encoded receptor-binding protein (RBP) interacts with its host's RBP binding target, and this new model offers opportunities for further theoretical and experimental studies to understand the infection mechanism of phages.

Comparative genomic analysis reveals the potential transmission of Vibrio parahaemolyticus from freshwater food to humans

Vibrio parahaemolyticus is an increasingly important foodborne pathogen that cause acute gastroenteritis in humans. However, the prevalence and transmission of this pathogen in freshwater food remains unclear. This study aimed to determine the molecular characteristics and genetic relatedness of V. parahaemolyticus isolates obtained from freshwater food, seafood, environmental, and clinical samples. A total of 138 (46.6%) isolates were detected from 296 food and environmental samples, and 68 clinical isolates from patients. Notably, V. parahaemolyticus was more prevalent in freshwater food (56.7%, 85/150) than in seafood (38.8%, 49/137). Virulence phenotype analyses revealed that the high motility of isolates from freshwater food (40.0%) and clinical isolates (42.0%) was higher than that of isolates from seafood (12.2%), whereas the biofilm-forming capacity of freshwater food isolates (9.4%) was lower than that of seafood (22.4%) and clinical isolates (15.9%). Virulence genes analysis showed that 46.4% of the clinical isolates contained the tdh gene encoding thermostable direct hemolysin (TDH) and only two freshwater food isolates contained the trh gene encoding TDH-related hemolysin (TRH). Multilocus sequence typing (MLST) analysis divided the 206 isolates into 105 sequence types (STs), including 56 (53.3%) novel STs. ST2583, ST469, and ST453 have been isolated from freshwater food and clinical samples. Whole-genome sequence (WGS) analyses revealed that the 206 isolates were divided into five clusters. Cluster II contained isolates from freshwater food and clinical samples, whereas the other clusters contained isolates from seafood, freshwater food, and clinical samples. In addition, we observed that ST2516 had the same virulence pattern, with a close phylogenetic relationship to ST3. The increased prevalence and adaption of V. parahaemolyticus in freshwater food is a potential cause of clinical cases closely related to the consumption of V. parahaemolyticus contaminated freshwater food.

Salmonella Enteritidis T1SS protein SiiD inhibits NLRP3 inflammasome activation via repressing the mtROS-ASC dependent pathway

Inflammasome activation is an essential innate immune defense mechanism against Salmonella infections. Salmonella has developed multiple strategies to avoid or delay inflammasome activation, which may be required for long-term bacterial persistence. However, the mechanisms by which Salmonella evades host immune defenses are still not well understood. In this study, Salmonella Enteritidis (SE) random insertion transposon library was screened to identify the key factors that affect the inflammasome activation. The type I secretion system (T1SS) protein SiiD was demonstrated to repress the NLRP3 inflammasome activation during SE infection and was the first to reveal the antagonistic role of T1SS in the inflammasome pathway. SiiD was translocated into host cells and localized in the membrane fraction in a T1SS-dependent and partially T3SS-1-dependent way during SE infection. Subsequently, SiiD was demonstrated to significantly suppress the generation of mitochondrial reactive oxygen species (mtROS), thus repressing ASC oligomerization to form pyroptosomes, and impairing the NLRP3 dependent Caspase-1 activation and IL-1β secretion. Importantly, SiiD-deficient SE induced stronger gut inflammation in mice and displayed NLRP3-dependent attenuation of the virulence. SiiD-mediated inhibition of NLRP3 inflammasome activation significantly contributed to SE colonization in the infected mice. This study links bacterial T1SS regulation of mtROS-ASC signaling to NLRP3 inflammasome activation and reveals the essential role of T1SS in evading host immune responses.

CCCTC-Binding Factor Mediates the Transcription of Insulin-Like Growth Factor Binding Protein 5 Through EZH2 in Ulcerative Colitis

BACKGROUND

Ulcerative colitis (UC) features chronic, non-infectious inflammation of the colon. Insulin-like growth factor binding protein 5 (IGFBP5) has been indicated to be related to various inflammation-related diseases. However, its association with UC remains largely unclear.

AIMS

Here, we investigate the role of IGFBP5 in colonic mucosal epithelial cell injury in UC.

METHODS

Differentially expressed genes in the colonic tissues of UC mice were screened using the Gene Expression Omnibus database, and IGFBP5 was identified. UC mice were developed using dextran sulfate sodium, and IGFBP5 expression in the colonic tissues of UC mice was confirmed by immunohistochemistry and RT-qPCR. The effects of IGFBP5 in vivo and in vitro were investigated by intraperitoneal injection of adeno-associated virus into UC mice or by transfection with an IGFBP5 overexpression plasmid into lipopolysaccharide-treated colonic mucosal epithelial cells. The mechanisms causing IGFBP5 deletion in UC were predicted by bioinformatics analysis and ChIP-qPCR and verified by rescue experiments.

RESULTS

IGFBP5 was reduced in UC. IGFBP5 impaired the NFκB pathway in the colonic tissue of UC mice and ameliorated inflammatory infiltration and colonic mucosal cell injury. IGFBP5 depletion was associated with H3K27me3 modification, which was induced by EZH2. CTCF was responsible for recruiting EZH2 to the promoter region of IGFBP5. CTCF inhibition repressed UC progression by reducing H3K27me3 modification via the discouragement of the enrichment of EZH2 in the IGFBP5 promoter.

CONCLUSIONS

CTCF modulates H3K27me3 modification of the IGFBP5 promoter by recruiting EZH2, thereby downregulating IGFBP5 to accentuate colonic mucosal epithelial cell injury in UC mice.

A low-cost technique for biodiesel production in Ankistrodesmus sp. EHY by using harvested microalgal effluent

The present study aims to use Ankistrodesmus sp. EHY to develop a viable and economic lipid production strategy using recycling of harvested microalgal effluent. In comparison to the control, the highest lipid content (52.4 %) and productivity (250.72 mg L^-1 d^-1) were achieved when 40 % recycled medium was used. Consistent with the trend of lipid accumulation, the six key lipogenetic genes were upregulated, as well as reactive oxygen species (ROS), glutathione (GSH) and genes encoding antioxidant enzymes during cultivation in recycled medium. Moreover, the consumption of dissolved organic carbon (DOC) and the increased humic acid (HA) in the recycled medium might also be associated with lipid biosynthesis. The biodiesel parameters of alga biomass-derived lipids were fitted to the standard of commercial biodiesel. In conclusion, this study offers an economically viable strategy for microalgal biofuel production and wastewater treatment using recycling of harvested microalgal effluent.

The DNA adenine methylase of Salmonella Enteritidis promotes their intracellular replication by inhibiting arachidonic acid metabolism pathway in macrophages

Macrophages can participate in immune responses by altering their metabolism, and play important roles in controlling bacterial infections. However, Salmonella Enteritidis can survive and proliferate in macrophages. After the deletion of DNA adenine methylase (Dam), the proliferation of Salmonella Enteritidis in macrophages decreased, the molecular mechanism is still unclear. After infecting macrophages with Salmonella Enteritidis wild type and dam gene deletion strains, intracellular metabolites were extracted and detected by non-targeted metabolomics and fatty acid targeted metabolomics. We found Dam had significant effects on arachidonic acid and related metabolic pathways in macrophages. The dam gene can promote the proliferation of Salmonella Enteritidis in macrophages by inhibiting the metabolic pathway of cytosolic phospholipase A2-mediated arachidonic acid production and conversion to prostaglandin E2 in macrophages, reducing the secretion of the pro-inflammatory factors IL-1β and IL-6. In addition, inhibition of arachidonic acid-related pathways in macrophages by Arachidonyl trifluoromethyl ketone could restore the proliferation of dam gene deletion strains in macrophages. This study explored the role of Dam in the process of Salmonella Enteritidis invading host cells from the perspective of host cell metabolism, and provides new insights into the immune escape mechanism of Salmonella Enteritidis.

Characterization of the RpoN regulon reveals the regulation of motility, T6SS2 and metabolism in Vibrio parahaemolyticus

Vibrio parahaemolyticus is a foodborne pathogen that can colonize the small intestine of the host and cause diarrhea. The alternative sigma factor RpoN plays a vital role in regulating motility, carbon utilization and affects host colonization in V. parahaemolyticus RIMD2210633. In this study, transcriptome and phenotypic analysis further expanded our understanding of the RpoN regulon in V. parahaemolyticus. A deletion mutant of rpoN (ΔrpoN) was subjected to RNA-seq for systemic identification of the RpoN-controlled genes. Compared with the wild-type (WT), 399 genes were differentially expressed in the ΔrpoN strain. Moreover, 264 genes were down-regulated in the ΔrpoN strain, including those associated with nitrogen utilization (VP0118), glutamine synthetase (VP0121), formate dehydrogenase (VP1511 and VP1513-VP1515), quorum sensing (opaR and luxZ), polar flagellar systems, and type VI secretion system 2 (T6SS2). Quantitative real-time reverse transcription PCR (qRT-PCR) and electrophoretic mobility shift assay (EMSA) further confirmed that RpoN could directly bind to the promoters of these genes associated with polar flagellar systems (flgB and fliE), lateral flagellar systems (flgB2 and lafA), T6SS2 (hcp2 and VPA1044) and glutamine synthetase (VP0121), and then positively regulate the expression of these systems. A RpoN-binding motif was identified in V. parahaemolyticus using the MEME suite and verified by the EMSA. Besides, the deletion of rpoN caused a significant decrease in hemolytic activity, adhesion, and cytotoxicity. Our results provide new cues to better understand the regulatory networks of RpoN protein to motility, T6SS2, and metabolism in V. parahaemolyticus.

Gamma-aminobutyric acid coupled with copper ion stress stimulates lipid production of green microalga Monoraphidium sp. QLY-1 through multiple mechanisms

Induction of copper ion (Cu²⁺) stress is a method used to increase lipid accumulation in microalgae, but it decreases cell growth. In this work, the impacts of gamma-aminobutyric acid (GABA) coupled with Cu²⁺ stress on the biomass and oil yield in Monoraphidium sp. QLY-1 were investigated. Results suggested that the combined treatment of GABA and Cu²⁺ resulted in a higher lipid content (55.13%) than Cu²⁺ treatment (48.43%). Furthermore, GABA addition upregulated the levels of lipid-relevant genes, cellular GABA, ethylene (ETH), and antioxidant enzyme activities and alleviated oxidative damage caused by Cu²⁺ stress. The autophagy-relevant gene atg8 was also upregulated by GABA treatment. Further exploration indicated that cell autophagy induced the lipid content up to 58.09% with GABA and Cu²⁺ stress treatment. This investigation demonstrates that the coupling strategy can stimulate lipid production and shed light on the underlying mechanisms in lipid biosynthesis, cell autophagy, and stress response of microalgae.

Coupling of myo-inositol with salinity regulates ethylene-induced microalgal lipid hyperproduction in molasses wastewater

With the goal of cost-effective and high-efficient microalgae-based biodiesel production, this study evaluated the feasibility of the joint strategy concerning myo-inositol (MI) and salinity stress on lipid productivity of Monoraphidium sp. QLY-1 in molasses wastewater (MW). The maximal lipid productivity (147.79 mg L^-1 d^-1) was obtained under combined 0.5 g L^-1 MI and 10 g L^-1 NaCl treatment, which was 1.40-fold higher than the control. Meanwhile, the nutrients removal from MW was markedly increased under MI-NaCl treatment. Moreover, exogenous MI upregulated key lipogenic genes' expressions, activated autophagic activity and ethylene (ET) signaling, and ultimately alleviated the salinity-induced damage via reactive oxygen species (ROS) signaling. Further pharmacologic experiment confirmed the indispensable role of ET in the lipogenesis progress under the combined treatment. These data demonstrated the combined salinity stress and MI treatment to be capable for lipid hyperproduction and wastewater nutrients removal, which contributes to practically integrating the microalgae cultivation with wastewater treatment.

Vibrio parahaemolyticus CadC regulates acid tolerance response to enhance bacterial motility and cytotoxicity

Pathogens adapted to sub-lethal acidic conditions could increase the virulence and survival ability under lethal conditions. In the aquaculture industry, feed acidifiers have been used to increase the growth of aquatic animals. However, there is limited study on the effects of acidic condition on the virulence and survival of pathogens in aquaculture. In this study, we investigated the survival ability of Vibrio parahaemolyticus at lethal acidic pH (4.0) after adapted the bacteria to sub-lethal acidic pH (5.5) for 1 hr. Our results indicated that the adapted strain increased the survival ability at lethal acidic pH invoked by an inorganic (HCl) or organic (citric) acid. RNA-sequencing (RNA-seq) results revealed that 321 genes were differentially expressed at the sub-lethal acidic pH including cadC, cadBA and groES/groEL relating to acid tolerance response (ATR), as well as genes relating to outer membrane, heat-shock proteins, phosphotransferase system and flagella system. Quantitative real-time polymerase chain reaction (qRT-PCR) confirmed that cadC and cadBA were upregulated under sub-lethal acidic conditions. The CadC protein could directly regulate the expression of cadBA to modulate the ATR in V. parahaemolyticus. RNA-seq data also indicated that 113 genes in the CadC-dependent way and 208 genes in the CadC-independent way were differentially expressed, which were related to the regulation of ATR. Finally, the motility and cytotoxicity of the sub-lethal acidic adapted wild type (WT) were significantly increased compared with the unadapted strain. Our results demonstrated that the dietary acidifiers may increase the virulence and survival of V. parahaemolyticus in aquaculture.

Prevalence and Characteristics of Salmonella spp. from a Pig Farm in Shanghai, China

Salmonella spp. is a major foodborne pathogen that is distributed among most pork production chains worldwide. This study aimed to investigate the dynamic changes in Salmonella spp. along the pig breeding process monthly from April 2018 to March 2019 in a pig farm in Shanghai, China, and identify the potential critical control points during the production. In total, 239 Salmonella spp. isolates were obtained from 1389 samples, in which Salmonella were detected from 26.3% (222/843) of fecal samples, 7.1% (17/240) of feed samples, and 0.0% (0/306) of both water and insect samples. Seven different serotypes were identified, with the predominant serotype being Salmonella Derby (21.8%), followed by Salmonella Typhimurium (18.8%), Salmonella Rissen (16.3%), Salmonella Mbandaka (12.6%), and Salmonella 1,4,[5],12:i:- (11.8%). Most probable number (MPN) analysis revealed that the load of Salmonella spp. gradually increased along the pig production chain, while the highest number of Salmonella spp. isolates was at the fattening stage (MPN value, 11-15 MPN/g). The pulsed-field gel electrophoresis showed that both Salmonella Typhimurium and Salmonella Derby isolates were grouped to six clusters. The antimicrobial resistance analyzed demonstrated that 80.0% of the isolates were of multidrug resistance and resistant to sulfamethoxazole (84.5%), lincomycin (89.4%), ampicillin (96.9%), oxytetracycline (93.8%), and tetracycline (95.1%). We further evaluated the Salmonella spp. Resistance to quaternary ammonium compounds (QACs) showed an increasing trend along with the testing period indicating that the use of QACs could induce the resistance of Salmonella spp. to QACs. Our study confirmed the dynamic changes in Salmonella spp. over time and space in this pig farm and identified feed and the fattening house as the key points for the prevention and control of Salmonella spp. contamination.

The rfbN gene of Salmonella Typhimurium mediates phage adsorption by modulating biosynthesis of lipopolysaccharide

The study of the interaction mechanism between bacteriophage and host is helpful in promoting development of bacteriophage applications. The mechanism of the interaction with the phage was studied by constructing the rfbN gene deletion and complemented with strains of Salmonella enterica subspecies enterica serovar Typhimurium (Salmonella Typhimurium, S. Typhimurium) D6. The rfbN gene deletion strain could not be lysed by phage S55 and led to a disorder of lipopolysaccharide (LPS) biosynthesis, which changed from the smooth type to rough type. Also, the RfbN protein lacking any of the three-segment amino acid (aa) sequences (90-120 aa, 121-158 aa, and 159-194 aa) produces the same result. Transmission electron microscopy and confocal microscopy assays demonstrated that phage S55 dramatically reduced adsorption to the rfbN deletion strain as compared to the wild strain D6. After co-incubation of the S55 with the purified smooth LPS, D6 could not be lysed, indicating that the smooth LPS binds to the S55 in vitro and then inhibits the cleavage activity of the S55. To sum up, the rfbN gene affects phage adsorption by regulating LPS synthesis. Furthermore, the functioning of the RfbN protein requires the involvement of multiple structures. To the best of our knowledge, this study is the first report of the involvement of the bacterial rfbN gene involved in the phage-adsorption process.

Binding site profiles and N-terminal minor groove interactions of the master quorum-sensing regulator LuxR enable flexible control of gene activation and repression

LuxR is a TetR family master quorum sensing (QS) regulator activating or repressing expression of hundreds of genes that control collective behaviors in Vibrios with underlying mechanism unknown. To illuminate how this regulator controls expression of various target genes, we applied ChIP-seq and DNase I-seq technologies. Vibrio alginolyticus LuxR controls expression of ∼280 genes that contain either symmetric palindrome (repDNA) or asymmetric (actDNA) binding motifs with different binding profiles. The median number of LuxR binding sites for activated genes are nearly double for that of repressed genes. Crystal structures of LuxR in complex with the respective repDNA and actDNA motifs revealed a new mode of LuxR DNA binding that involves contacts of its N-terminal extension to the minor groove. The N-terminal contacts mediated by Arginine-9 and Arginine-11 differ when LuxR binds to repDNA vs actDNA, leading to higher binding affinity at repressed targets. Moreover, modification of LuxR binding sites, binding profiles, and N-terminal extension have important consequences on QS-regulated phenotypes. These results facilitate fundamental understanding of the high flexibility of mechanisms of LuxR control of gene activation and repression in Vibrio QS, which may facilitate to design QS inhibiting chemicals that interfere with LuxR regulation to effectively control pathogens.

Genome-Wide Identification of Genes Involved in Acid Stress Resistance of Salmonella Derby

Resistance to and survival under acidic conditions are critical for Salmonella to infect the host. As one of the most prevalent serotypes identified in pigs and humans, how S. Derby overcomes acid stress remains unclear. Here, we de novo sequenced the genome of a representative S. Derby strain 14T from our S. Derby strain stock and identified its acid resistance-associated genes using Tn-seq analysis. A total of 35 genes, including those belonging to two-component systems (TCS) (cpxAR), the CRISPR-Cas system (casCE), and other systems, were identified as essential for 14T to survive under acid stress. The results demonstrated that the growth curve and survival ability of ΔcpxA and ΔcpxR were decreased under acid stress, and the adhesion and invasion abilities to the mouse colon cancer epithelial cells (MC38) of ΔcpxR were also decreased compared with the wild type strain, suggesting that the TCS CpxAR plays an essential role in the acid resistance and virulence of S. Derby. Also, CasC and CasE were found to be responsible for acid resistance in S. Derby. Our results indicate that acid stress induces multiple genes’ expression to mediate the acid resistance of S. Derby and enhance its pathogenesis during an infection.

Rapid and Accurate Campylobacter jejuni Detection With CRISPR-Cas12b Based on Newly Identified Campylobacter jejuni-Specific and -Conserved Genomic Signatures

Campylobacter jejuni is among the most prevalent foodborne zoonotic pathogens leading to diarrheal diseases. In this study, we developed a CRISPR-Cas12b-based system to rapidly and accurately detect C. jejuni contamination. Identification of C. jejuni-specific and -conserved genomic signatures is a fundamental step in development of the detection system. By comparing C. jejuni genome sequences with those of the closely related Campylobacter coli, followed by comprehensive online BLAST searches, a 20-bp C. jejuni-conserved (identical in 1024 out of 1037 analyzed C. jejuni genome sequences) and -specific (no identical sequence detected in non-C. jejuni strains) sequence was identified and the system was then assembled. In further experiments, strong green fluorescence was observed only when C. jejuni DNA was present in the system, highlighting the specificity of this system. The assay, with a sample-to-answer time of ∼40 min, positively detected chicken samples that were contaminated with a dose of approximately 10 CFU C. jejuni per gram of chicken, which was >10 times more sensitive than the traditional Campylobacter isolation method, suggesting that this method shows promise for onsite C. jejuni detection. This study provides an example of bioinformatics-guided CRISPR-Cas12b-based detection system development for rapid and accurate onsite pathogen detection.

WbaP is required for swarm motility and intramacrophage multiplication of Salmonella Enteritidis spiC mutant by glucose use ability

Salmonella spp. can survive and replicate in macrophage cells to cause persistent infection, SpiC is a necessary T3SS effector, but its pathogenic mechanism is still not known completely. In our study, Salmonella Enteritidis spiC mutant (SEΔspiC) was found to have stronger swarming motility and intramacrophage hyperproliferation which was closely related to glucose metabolism. SEΔspiC wbaP::Tn5 mutant was screened out by transposon mutagenesis, which had weaker swarming motility and intramacrophage replication ability than SEΔspiC in the presence of glucose. Bioinformatics displayed that undecaprenyl-phosphate galactose phosphotransferase (Wbap), encoded by wbaP gene, was a key enzyme for glucose metabolism and Lipopolysaccharide(LPS) synthesis, which confirmed our outcome that Wbap was involved in intramacrophage replication ability by glucose use in addition to swarming motility based on SEΔspiC. This discovery will further promote the understanding of the interaction between wbaP gene and spiC gene and the intracellular Salmonella replication mechanism.

Nucleolar c-Myc recruitment by a Vibrio T3SS effector promotes host cell proliferation and bacterial virulence

Pathogen type 3 secretion systems (T3SS) manipulate host cell pathways by directly delivering effector proteins into host cells. In Vibrio parahaemolyticus, the leading cause of bacterial seafood-borne diarrheal disease, we showed that a T3SS effector, VgpA, localizes to the host cell nucleolus where it binds Epstein-Barr virus nuclear antigen 1-binding protein 2 (EBP2). An amino acid substitution in VgpA (VgpA^L10A ) did not alter its translocation to the nucleus but abolished the effector's capacity to interact with EBP2. VgpA-EBP2 interaction led to the re-localization of c-Myc to the nucleolus and increased cellular rRNA expression and proliferation of cultured cells. The VgpA-EBP2 interaction elevated EBP2's affinity for c-Myc and prolonged the oncoprotein's half-life. Studies in infant rabbits demonstrated that VgpA is translocated into intestinal epithelial cells, where it interacts with EBP2 and leads to nucleolar re-localization of c-Myc. Moreover, the in vivo VgpA-EBP2 interaction during infection led to proliferation of intestinal cells and heightened V. parahaemolyticus' colonization and virulence. These observations suggest that direct effector stimulation of a c-Myc controlled host cell growth program can contribute to pathogenesis.

Identification of a novel bacterial receptor that binds tail tubular proteins and mediates phage infection of Vibrio parahaemolyticus

The adsorption of phages to hosts is the first step of phage infection. Studies have shown that tailed phages use tail fibres or spikes to recognize bacterial receptors and mediate adsorption. However, whether other phage tail components can also recognize host receptors is unknown. To identify potential receptors, we screened a transposon mutagenesis library of the marine pathogen Vibrio parahaemolyticus and discovered that a vp0980 mutant (vp0980 encodes a predicted transmembrane protein) could not be lysed by phage OWB. Complementation of this mutant with wild-type vp0980 in trans restored phage-mediated lysis. Phage adsorption and confocal microscopy assays demonstrated that phage OWB had dramatically reduced adsorption to the vp0980 mutant compared to that to the wild type. Pulldown assays showed that phage tail tubular proteins A and B (TTPA and TTPB) interact with Vp0980, suggesting that Vp0980 is a TTPA and TTPB receptor. Vp0980 lacking the outer membrane region (aa 114–127) could not bind to TTPA and TTPB, resulting in reduced phage adsorption. These results strongly indicated that TTPA and TTPB binding with their receptor Vp0980 mediates phage adsorption and subsequent bacterial lysis. To the best of our knowledge, this study is the first report of a bacterial receptor for phage tail tubular proteins.

Essential role of Salmonella Enteritidis DNA adenine methylase in modulating inflammasome activation

Background

Salmonella Enteritidis (SE) is one of the major foodborne zoonotic pathogens of worldwide importance which can induce activation of NLRC4 and NLRP3 inflammasomes during infection. Given that the inflammasomes play an essential role in resisting bacterial infection, Salmonella has evolved various strategies to regulate activation of the inflammasome, most of which largely remain unclear.

Results

A transposon mutant library in SE strain C50336 was screened for the identification of the potential factors that regulate inflammasome activation. We found that T3SS-associated genes invC, prgH, and spaN were required for inflammasome activation in vitro. Interestingly, C50336 strains with deletion or overexpression of Dam were both defective in activation of caspase-1, secretion of IL-1β and phosphorylation of c-Jun N-terminal kinase (Jnk). Transcriptome sequencing (RNA-seq) results showed that most of the differentially expressed genes and enriched KEGG pathways between the C50336-VS-C50336Δdam and C50336-VS-C50336::dam groups overlapped, which includes multiple signaling pathways related to the inflammasome. C50336Δdam and C50336::dam were both found to be defective in suppressing the expression of several anti-inflammasome factors. Moreover, overexpression of Dam in macrophages by lentiviral infection could specifically enhance the activation of NLRP3 inflammasome independently via promoting the Jnk pathway.

Conclusions

These data indicated that Dam was essential for modulating inflammasome activation during SE infection, there were complex and dynamic interplays between Dam and the inflammasome under different conditions. New insights were provided about the battle between SE and host innate immunological mechanisms.

Molecular characterisation, expression and functional feature of TRAF6 in the King pigeon (Columba livia)

TNF receptor-associated factor 6 (TRAF6) is a signal transducer, which plays a pivotal role in triggering a variety of signalling cascades. Here, we cloned and identified the TRAF6 gene from the King pigeon. The open reading frame sequence of pigeon TRAF6 (piTRAF6) is 1638 bp long and encodes a 545 aa protein, including a low-complexity domain, RING finger, Zinc finger, coiled coil domain, and meprin and TRAF homology domain. The aa sequence of piTRAF6 shared a strong identity with that of other birds. PiTRAF6 transcripts were broadly expressed in all the tested tissues; piTRAF6 levels were the highest and lowest in the heart and stomach, respectively. Overexpression of piTRAF6 activated NF-κB in a dose-dependent manner and induced IFN-β expression. Upon piTRAF6 knockdown by small interfering RNAs, NF-κB activation was markedly inhibited in HEK293T cells. The expression of piTRAF6, as well as pro-inflammatory cytokines and antiviral molecules, were obviously increased after TLR ligand stimulation and Newcastle disease virus or Salmonella Pullorum inoculation. These results suggest that piTRAF6 may play a key immunoregulatory role in the innate immune response against viral and bacterial infections.

Skin-patch of Xin Huang Pian on relieving joint symptoms in patients with acute gouty arthritis: A Randomized, Double-Blind, Active-Controlled Trial

AIMS

To evaluate the effectiveness and safety of Xin Huang Pian skin patches for patients with acute gouty arthritis.

BACKGROUND

In China, patients with acute gouty arthritis benefit from skin patcheses with herbal medicines. But the clinical effects of skin patches with Xin Huang Pian are rarely reported.

DESIGN

A Randomized, Double-Blind, Active-Controlled Trial.

METHODS

The trial was performed from January 2015-December 2018 at the First Affiliated Hospital of Sun Yat-sen University in China. It was conducted with one intervention group (skin patches of Xin Huang Pian, N = 30) and one active control group (skin patches of Diclofenac Diethylamine Emulgel, N = 31). Participants and study investigators were both blinded to the treatment assignments. The primary outcomes were the improvement of joints' symptoms. The secondary outcomes were changes in white blood cells, erythrocyte sedimentation rate and C-reactive protein.

RESULTS

Skin patches of Xin Huang Pian showed quick effect on decreasing joint pain at 3rd day of treatment. Wherever only at 7th day, Diclofenac Diethylamine Emulgel markedly lowered joint pain. Xin Huang Pian also showed superior effect than Diclofenac Diethylamine Emulgel on improving joint swelling and range of motion and decreasing the levels of C-reactive protein and erythrocyte sedimentation rate. No adverse reactions were observed in skin patches of Xin Huang Pian treatment.

CONCLUSION

Skin patches of Xin Huang Pian appeared to be safe and efficacious for relieving joint symptoms in patients with acute gouty arthritis. The mechanism might be associated with the decreased levels of C-reactive protein and erythrocyte sedimentation rate.

IMPACT

Skin-patcheses with Xin Huang Pian are more effective than Diclofenac Diethylamine Emulgel on improving joint pain, swelling and range of motion. Xin Huang Pian treatment showed superior effects compared with Diclofenac Diethylamine Emulgel on decreasing levels of C-reactive protein and erythrocyte sedimentation rate. Patients with acute gouty arthritis may benefit from skin patches of Xin Huang Pian for effective relief from joint pain and swelling. Chinese Clinical Trial Registration: ChiCTR-TRC-1300 4122.

Transcriptomic analysis of PhoR reveals its role in regulation of swarming motility and T3SS expression in Vibrio parahaemolyticus

Vibrio parahaemolyticus is a common foodborne pathogen in seafood and represents a major threat to human health worldwide. In this study, we identified that PhoR, a histidine kinase, is involved in the regulation of swarming and flagella assembly. RNA sequencing analysis showed that 1122 genes were differentially expressed in PhoR mutant, including 394 upregulated and 728 downregulated genes. KEGG enrichment and heatmap analysis demonstrated that the bacterial secretion system, flagella assembly and chemotaxis pathways were significantly downregulated in PhoR mutant, while the microbial metabolism in diverse environments and carbon metabolism pathways were upregulated in PhoR mutant. qRT-PCR further confirmed that genes responsible for the type III secretion system (T3SS), swarming and the thermostable direct hemolysin were positively regulated by PhoR. Phosphorylation assays suggested that PhoR was highly activated in BHI medium compared to LB medium. Taken together, these data suggested that activated PhoR contributes to the expression of swarming motility and secretion system genes in Vibrio parahaemolyticus.

Prevalence of Salmonella Isolates and Their Distribution Based on Whole-Genome Sequence in a Chicken Slaughterhouse in Jiangsu, China

Salmonella has been known as the most important foodborne pathogen, which can infect humans via consuming contaminated food. Chicken meat has been known as an important vehicle to transmit Salmonella by the food supply chain. This study determined the prevalence, antimicrobial resistance, and genetic characteristics of Salmonella at different chicken slaughtering stages in East China. In total, 114 out of 200 (57%) samples were Salmonella positive, while Salmonella contamination was gradually increasing from the scalding and unhairing stage (17.5%) to the subdividing stage (70%) throughout the slaughtering. Whole-genome sequencing (WGS) was then performed to analyze the serotype, antimicrobial resistance gene profiles, and genetic relationship of all Salmonella isolates. The most common serotypes were S. Kentucky (51/114, 44.7%) and S. Enteritidis (37/114, 32.5%), which were distributed throughout the four slaughtering stages, and were also identified in the corresponding environments. The multilocus sequence typing (MLST) analysis revealed that seven sequence types (STs) were occupied by six different serotypes, respectively. Only S. Kentucky had two STs, ST314 was the predominant ST shared by 50 isolates, while the ST198 has 1 isolate. The antimicrobial resistance gene analysis demonstrated that most of the strains belonging to S. Kentucky (39/51, 76.5%) and S. Indiana (15, 100%) contained over five groups of antimicrobial resistance genes. Based on the core genome analysis, 50 S. Kentucky isolates were genetically identical, indicating that one S. Kentucky strain with the same genetic background was prevalent in the chicken slaughtering line. Although 37 S. Enteritidis isolates only had three different antimicrobial resistance gene profiles, the core genome sequence analysis subtyped these S. Enteritidis isolates into five different clusters, which revealed the diverse genetic background of S. Enteritidis in the slaughterhouse. The antimicrobial resistance phenotypes were consistent with the presence of the corresponding resistance genes of S. Kentucky and S. Enteritidis, including tetA, floR, blaTEM-1B, strA/B, sul1/sul2, and gyrA (D87Y). Our study observed a high prevalence of Salmonella in the chicken slaughter line and identified the slaughtering environment as a main source of causing Salmonella cross-contamination during chicken slaughtering. Further studies will be needed to limit the transmission of Salmonella in the slaughterhouse.

Associations between Serum Sex Hormone Concentrations and Telomere Length among U.S. Adults, 1999-2002

BACKGROUND AND OBJECTIVES

Sex hormone concentrations and telomere length are age related responses of human body, while whether there is a direct relation between sex hormone and telomere length is uncertain. Therefore, we used the data of National Health and Nutrition Examination Survey (NHANES) to quantify their direct association.

RESEARCH DESIGN AND METHODS

A total of 710 women aged 35-60 years and 539 men aged 20-85 years were included from two cycles of the NHANES (1999-2002). Telomere length relative to standard reference DNA (T/S ratio) was measured using quantitative polymerase chain reaction method. Seven hormones in serum (5 in men and 2 in women) were assayed. Logistic regressions were used to calculate the odds ratios to evaluate the telomere length-sex hormones association.

RESULTS

Men with vigorous physical activity (71.1%) and without history of cardiovascular diseases, diabetes, and lipid-lowering drugs using tended to have a longer telomere length (all P-values < 0.05); while women with longer sedentary time, smaller pregnant or live birth, and with older ages of firth/last birth were likely with longer telomere length (all P-values < 0.05). After adjusted for potential confounders, only anti-Mullerian hormone was positively and stably associated with short leukocytes telomere length in men (OR: 1.098; 95% CI: 1.034, 1.165). We did not detect any significant association of short telomere length with sex hormones in men and women. Discussion and Implications: Serum anti-Mullerian hormone in men was positively and stably associated with telomere length. More large-scaled and well-designed prospective studies are warranted to reconfirm our conclusions.

Molecular cloning and functional analysis of TRAF6 from Yangzhou great white goose Anser anser

TNF receptor-associated factor 6 (TRAF6) is an adaptor protein and an E3 ubiquitin ligase mediating multiple cell signaling pathway activation in a context-dependent manner. TRAF6 plays critical roles in innate immune response and regulates function of antigen-presenting cells. Here, we cloned the goose TRAF6 (goTRAF6) gene from a healthy Yangzhou great white goose (Anser anser), which had a typical TRAF structure and shared a high-sequence identity with TRAF6 of other birds. Quantitative real-time PCR revealed that goTRAF6 mRNA was broadly expressed in all the studied tissues, with highest expression in the heart and pectoral muscle. Overexpression of goTRAF6 caused NF-κB activation in a dose-dependent manner and substantially upregulated IFN-β expression in HEK293T cells. Following Toll-like receptor (TLR) ligand stimulation of goose peripheral blood mononuclear cells, goTRAF6 and downstream inflammatory cytokine mRNA levels considerably up-regulated, especially at early stages. Salmonella Enteritidis challenge caused overexpression of goTRAF6 and cytokine mRNA in all the examined organs. These findings demonstrated that goTRAF6 played a substantial role in TLR-TRAF6 signaling cascade, and further contributed to the antibacterial-responses in host.

Immunogenic potential and protective efficacy of a sptP deletion mutant of Salmonella Enteritidis as a live vaccine for chickens against a lethal challenge

Salmonella Enteritidis (SE) is a highly adapted pathogen causing severe economic losses in the poultry industry worldwide. Chickens infected by SE are a major source of human food poisoning. Vaccination is an effective approach to control SE infections. This study evaluated the immunogenicity and protective efficacy of a SE sptP deletion mutant (C50336ΔsptP) as a live attenuated vaccine (LAV) candidate in chickens. 14 day-old specific pathogen-free (SPF) chickens were intramuscularly immunized with various doses of C50336ΔsptP. Several groups of chickens were challenged with the virulent wild-type SE strain Z-11 via the same route at 14 days post vaccination. Compared to the control group, the groups vaccinated with 1 × 10⁶, 1 × 10⁷ and 1 × 10⁸ colony-forming units (CFU) of C50336ΔsptP exhibited no clinical symptoms after immunization. Only slight pathological changes occurred in the organs of the 1 × 10⁹ CFU vaccinated group. C50336ΔsptP bacteria were cleared from the organs of immunized chickens within 14 days after vaccination. Lymphocyte proliferation and serum cytokine analyses indicated that significant cellular immune responses were induced after the vaccination of C50336ΔsptP. Compared to the control group, specific IgG antibody levels increased significantly in vaccinated chickens, and the levels increased markedly after the challenge. The 1 × 10⁷, 1 × 10⁸, and 1 × 10⁹ CFU vaccinated chickens groups showed no clinical symptoms or pathological changes, and no death after the lethal challenge. Whereas severe clinical signs of disease and pathological changes were observed in the control group chickens after the challenge. These results suggest that a single dose of C50336ΔsptP could be an effective LAV candidate to against SE infection in chickens.

Components characterisation of Berchemia lineata (L.) DC. by UPLC-QTOF-MS/MS and its metabolism with human liver microsomes

Investigations were performed on the determination of the main components in Berchemia lineata (L.) DC. (BL) and its metabolism with human liver microsomes (HLM). A total of 35 compounds were detected in BL extracts and 25 of them including 6 naphthopyrones, 10 flavonoids, 2 phenolic acids, 2 phenols, 4 fatty acids and 1 quinone were unambiguously or tentatively identified by UPLC-QTOF-MS/MS. Among them, naphthopyrones were first identified in BL extracts and labelled in chromatography. In addition, the weak inhibitory effects of BL extracts (IC₅₀＝149.25 μg/mL) and rubrofusarin-6-O-α-L-rhamnosyl-(1-6)-O-β-D-glu-copyranside (the main component of BL extracts, M₀; IC₅₀＝82.14 μM) on CYP3A4 were also proved using testosterone as specific probe drug. The main metabolic pathway of M₀ by HLM was hydroxylation in its aglycone, the metabolite was tentatively identified as 10-hydroxy-rubrofusarin-6-O-α-L-rhamnosyl-(1-6)-O-β-D-glucopyranside. Components characterisation and the metabolism with HLM could help the further development and application of BL.

RETRACTED: Dissection of ToxR-dependent and ToxR-independent stress-regulated pathways in Vibrio parahaemolyticus

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the authors. After having been alerted by an anonymous reader the authors found out that in order to substantiate one of their conclusions (DeltaToxR-reduced killing activity is mediated via T6SS2) more experiments are needed. To avoid any potentially wrong conclusions being published, the authors decided to retract the article and to resubmit their manuscript once the additional experiments have been completed. The Editor-in-Chief agreed to the retraction. The authors wish to apologize for any inconvenience caused.

Application of two alternative shutdown severe accident management guideline (SSAMG) entry conditions for CPR1000

Recently, with the development and application of full-scope level 2 probabilistic safety assessment (PSA) method around the world, severe accident phenomena during shutdown and low power conditions have aroused extensive attention in nuclear industry. And the shutdown severe accident management guideline (SSAMG) is claimed to be developed, and the verification of the traditional and alternative entry conditions is the first consideration in this procedure. Thus in this paper, the feasibility of the hot leg pipe temperature and the modified jakob number are analyzed based on a SBO sequence firstly. Subsequently, verification work is conducted under a SBO sequence with pressurizer manhole open and a SBO sequence along with SBLOCA. The results proved the excellent effectiveness of the two parameters to be used as alternative SSAMG entry conditions. Also, a relational figure is constructed based on the results of diverse sequences with various primary system pressure to provide visualized guidance for operators. What's more, the value of modified jakob number which indicates the SSAMG entry is thought to be in the range of 0.5–1.