The FabA-FabB Pathway Is Not Essential for Unsaturated Fatty Acid Synthesis but Modulates Diffusible Signal Factor Synthesis in Xanthomonas campestris pv. campestris.

Most bacteria use type II fatty acid synthesis (FAS) systems for synthesizing fatty acids, of which the conserved FabA-FabB pathway is considered to be crucial for unsaturated fatty acid (UFA) synthesis in gram-negative bacteria. Xanthomonas campestris pv. campestris, the phytopathogen of black rot disease in crucifers, produces higher quantities of UFAs under low-temperature conditions for increasing membrane fluidity. The fabA and fabB genes were identified in the X. campestris pv. campestris genome by BLAST analysis; however, the growth of the X. campestris pv. campestris fabA and fabB deletion mutants was comparable to that of the wild-type strain in nutrient and minimal media. The X. campestris pv. campestris ΔfabA and ΔfabB strains produced large quantities of UFAs and, altogether, these results indicated that the FabA-FabB pathway is not essential for growth or UFA synthesis in X. campestris pv. campestris. We also observed that the expression of X. campestris pv. campestris fabA and fabB restored the growth of the temperature-sensitive Escherichia coli fabA and fabB mutants CL104 and CY242, respectively, under non-permissive conditions. The in-vitro assays demonstrated that the FabA and FabB proteins of X. campestris pv. campestris catalyzed FAS. Our study also demonstrated that the production of diffusible signal factor family signals that mediate quorum sensing was higher in the X. campestris pv. campestris ΔfabA and ΔfabB strains and greatly reduced in the complementary strains, which exhibited reduced swimming motility and attenuated host-plant pathogenicity. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.

A ProQ/FinO family protein involved in plasmid copy number control favours fitness of bacteria carrying mcr-1-bearing IncI2 plasmids.

The plasmid-encoded colistin resistance gene mcr-1 challenges the use of polymyxins and poses a threat to public health. Although IncI2-type plasmids are the most common vector for spreading the mcr-1 gene, the mechanisms by which these plasmids adapt to host bacteria and maintain resistance genes remain unclear. Herein, we investigated the regulatory mechanism for controlling the fitness cost of an IncI2 plasmid carrying mcr-1. A putative ProQ/FinO family protein encoded by the IncI2 plasmid, designated as PcnR (plasmid copy number repressor), balances the mcr-1 expression and bacteria fitness by repressing the plasmid copy number. It binds to the first stem-loop structure of the repR mRNA to repress RepA expression, which differs from any other previously reported plasmid replication control mechanism. Plasmid invasion experiments revealed that pcnR is essential for the persistence of the mcr-1-bearing IncI2 plasmid in the bacterial populations. Additionally, single-copy mcr-1 gene still exerted a fitness cost to host bacteria, and negatively affected the persistence of the IncI2 plasmid in competitive co-cultures. These findings demonstrate that maintaining mcr-1 plasmid at a single copy is essential for its persistence, and explain the significantly reduced prevalence of mcr-1 following the ban of colistin as a growth promoter in China.

Dietary metabolizable energy and crude protein levels affect the performance, egg quality and biochemical parameters of a dual-purpose chicken.

Effects of dietary metabolizable energy (ME) and crude protein (CP) level on performance, egg quality and biochemical parameters were studied in a dual-purpose chicken-Beijing You Chicken (BYC) at peak laying period. A 3 × 3 factorial experiment was arranged, including 3 levels of dietary ME (11.31, 11.51, 11.71 MJ/kg) and 3 levels of dietary CP (14%, 15%, 16%). The results showed that dietary CP level alone and the interaction of ME by CP affected the total feed intake (TFI) during 27-30 wks, dietary ME level affected the mortality rate of 27-34 wks of age (p = 0.018), with the highest mortality rate found in 11.31 MJ/kg group (3.10%). The albumen height (AH), Haugh unit (HU) and egg grade (EG) of 16% group was higher than those in 14% and 15% groups (p < 0.05). Serum immunoglobulin G content in 11.31 MJ/kg group was lower than in 11.51 MJ/kg and 11.71 MJ/kg groups (p = 0.037). The present study suggested that dietary levels of 11.51 MJ/kg ME and 16.0% CP are enough to maintain the performance and egg quality of BYC at peak laying period. 11.31 MJ/kg ME increased the mortality of the chicken, which may be related to the decrease of the humoral immune function and antioxidative capability.

A novel strategy to control Pseudomonas syringae through inhibition of type III secretion system.

Pseudomonas syringae (P. syringae) is a highly prevalent Gram-negative pathogen with over 60 pathogenic variants that cause yield losses of up to 80% in various crops. Traditional control methods mainly involve the application of antibiotics to inactivate pathogenic bacteria, but large-scale application of antibiotics has led to the development of bacterial resistance. Gram-negative pathogens including P. syringae commonly use the type III secretion system (T3SS) as a transport channel to deliver effector proteins into host cells, disrupting host defences and facilitating virulence, providing a novel target for antibacterial drug development. In this study, we constructed a high-throughput screening reporter system based on our previous work to screen for imidazole, oxazole and thiazole compounds. The screening indicated that the three compounds (II-14, II-15 and II-24) significantly inhibited hrpW and hrpL gene promoter activity without influencing the growth of P. syringae, and the inhibitory activity was better than that of the positive control sulforaphane (4-methylsulfinylbutyl isothiocyanate, SFN) at 50 µM. Three compounds suppressed the transcript levels of representative T3SS genes to different degrees, suggesting that the compounds may suppress the expression of T3SS by modulating the HrpR/S-HrpL regulatory pathway. Inoculation experiments indicated that all three compounds suppressed the pathogenicity of Pseudomonas syringae pv. tomato DC3000 in tomato and Pseudomonas syringae pv. phaseolicola 1448A in bean to varying degrees. One representative compound, II-15, significantly inhibited the secretion of the Pst DC3000 AvrPto effector protein. These findings provide a theoretical basis for the development of novel P. syringae T3SS inhibitors for application in disease prevention and control.

HetI-Like Phosphopantetheinyl Transferase Posttranslationally Modifies Acyl Carrier Proteins in Xanthomonas spp.

In Xanthomonas spp., the biosynthesis of the yellow pigment xanthomonadin and fatty acids originates in the type II polyketide synthase (PKS II) and fatty acid synthase (FAS) pathways, respectively. The acyl carrier protein (ACP) is the central component of PKS II and FAS and requires posttranslational phosphopantetheinylation to initiate these pathways. In this study, for the first time, we demonstrate that the posttranslational modification of ACPs in X. campestris pv. campestris is performed by an essential 4'-phosphopantetheinyl transferase (PPTase), XcHetI (encoded by Xc_4132). X. campestris pv. campestris strain XchetI could not be deleted from the X. campestris pv. campestris genome unless another PPTase-encoding gene such as Escherichia coli acpS or Pseudomonas aeruginosa pcpS was present. Compared with wild-type strain X. campestris pv. campestris 8004 and mutant XchetI::PapcpS, strain XchetI::EcacpS failed to generate xanthomonadin pigments and displayed reduced pathogenicity for the host plant, Brassica oleracea. Further experiments showed that the expression of XchetI restored the growth of E. coli acpS mutant HT253 and, when a plasmid bearing XchetI was introduced into P. aeruginosa, pcpS, which encodes the sole PPTase in P. aeruginosa, could be deleted. In in vitro enzymatic assays, XcHetI catalyzed the transformation of 4'-phosphopantetheine from coenzyme A to two X. campestris pv. campestris apo-acyl carrier proteins, XcAcpP and XcAcpC. All of these findings indicate that XcHetI is a surfactin PPTase-like PPTase with a broad substrate preference. Moreover, the HetI-like PPTase is ubiquitously conserved in Xanthomonas spp., making it a potential new drug target for the prevention of plant diseases caused by Xanthomonas.[Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.

Tumor suppressive lncRNA MEG3 binds to EZH2 and enhances CXCL3 methylation in gallbladder cancer.

Gallbladder cancer is a malignant tumor with a high mortality rate. Accumulating evidence supports that lncRNA MEG3 may halt the progression of gallbladder cancer, while the downstream mechanism is rarely studied. Thus, we aim to investigate the molecular basis of the tumor-suppressing role of lncRNA MEG3 in gallbladder cancer. The expression of lncRNA MEG3 and CXCL3 was measured in patient serum and cell lines of gallbladder cancer. The viability, apoptosis, migration, and invasion of gallbladder cancer cells were assessed following ectopic MEG3 expression, as detected by CCK-8, flow cytometry, and Transwell assays. The interaction among lncRNA MEG3, EZH2, and CXCL3 was explored through ChIP, RNA pull-down, and RIP assays. The effects of lncRNA MEG3 and CXCL3 on tumor growth were evaluated by a mouse xenograft model. lncRNA MEG3 was expressed at a low level in gallbladder cancer patient serum and cell lines, while CXCL3 was highly expressed. MEG3 overexpression repressed the malignant behaviors of gallbladder cancer cells and promoted their apoptosis. MEG3 was mainly localized in the nucleus. MEG3 bound to EZH2, and EZH2 catalyzed the H3K27 trimethylation of the CXCL3 promoter region. MEG3 downregulated CXCL3 by activating EZH2-mediated H3K27 trimethylation of CXCL3; MEG3 overexpression attenuated cancer cell malignant behaviors in vitro and suppressed tumor growth in vivo in gallbladder cancer by inhibiting CXCL3 expression. Altogether, our results indicate that lncRNA MEG3 impedes gallbladder cancer development via the EZH2-CXCL3 axis, offering potential biomarkers for gallbladder cancer management.

Cdc42 Promotes Axonogenesis of Primary Hippocampal Neurons by Inhibiting Glycogen Synthase Kinase-3ß.

BACKGROUND: Progressive axon degeneration is a common pathological feature of neurodegenerative diseases. Cdc42 is a member of the Rho GTPase family that participates in axonogenesis. GSK-3ß is a serine/threonine kinase highly implicated in neuronal development and neurodegeneration. This study aimed to examine whether cdc42 promotes axonogenesis by regulating GSK-3ß activity. METHODS: Hippocampal neurons were isolated from neonatal Sprague-Dawley rats and transfected with designated plasmid vectors to alter the activities of cdc42 and GSK-3ß. LiCl treatment was used to inhibit the GSK-3ß activity in primary neurons. GSK-3ß activity was determined by an enzyme activity assay kit. Immunofluorescence staining was used to detect axons stained with anti-Tau-1 antibody and dendrites stained with anti-MAP2 antibody. RESULTS: Transfection with an active cdc42 mutant (cdc42F28L) decreased the activity of GSK-3ß and induced axonogenesis in primary rat hippocampal neurons, while transfection with a negative cdc42 mutant (cdc42N17) resulted an opposite effect. Moreover, transfection with plasmid vectors carrying wild-type GSK-3ß or a constitutively active GSK3ß mutant (GSK-3ß S9A) increased the activity of GSK-3ß and attenuated axonogenesis of primary hippocampal neurons with excessive cdc42 activity, whereas inhibition of GSK-3ß by LiCl abolished the inhibitory effect of the negative cdc42 mutant on axonogenesis. CONCLUSIONS: This study suggests that cdc42 induces axonogenesis of primary rat hippocampal neurons via inhibiting GSK-3ß activity. These findings support further investigation into the mechanisms of cdc42/GSK-3ß-mediated axonogenesis.

Cdc42 Facilitates Axonogenesis by Enhancing Microtubule Stabilization in Primary Hippocampal Neurons.

The establishment of polarity is an essential process in early neuronal development. Cdc42, a GTPase of the Rho family, is a key regulator of cytoskeletal dynamics and neuronal polarity. However, the mechanisms underlying the action of cdc42 in regulating axonogenesis have not been elucidated. Here, we expressed wild-type cdc42, a constitutively active cdc42 mutant (cdc42F28L) and a dominant negative cdc42 mutant (cdc42N17), respectively, in the primary hippocampal neurons to alter the activity of cdc42. We found that cdc42 activities were paralleled with the capacities to promote axonogenesis in the cultured neurons. Cdc42 also enhanced microtubule stability in the cultured neurons. Pharmacologically stabilizing microtubules significantly abrogated the defective axonogenesis induced by cdc42 inhibition. Moreover, cdc42 promoted the dephosphorylation of collapsing response mediator protein-2 (CRMP-2) at Thr514 by increasing GSK-3ß phosphorylation at Ser9 in the cultured neurons. These findings suggest that cdc42 may facilitate axonogenesis by promoting microtubule stabilization in rat primary hippocampal neurons.

Central 5-hydroxytryptamine (5-HT) mediates colonic motility by hypothalamus oxytocin-colonic oxytocin receptor pathway.

Gut-derived 5-hydroxytryptamine (5-HT) is well known for its role in mediating colonic motility function. However, it is not very clear whether brain-derived 5-HT is involved in the regulation of colonic motility. In this study, we used central 5-HT knockout (KO) mice to investigate whether brain-derived 5-HT mediates colonic motility, and if so, whether it involves oxytocin (OT) production in the hypothalamus and OT receptor in the colon. Colon transit time was prolonged in KO mice. The OT levels in the hypothalamus and serum were decreased significantly in the KO mice compared to wild-type (WT) controls. OT increased colonic smooth muscle contraction in both KO and WT mice, and the effects were blocked by OT receptor antagonist and tetrodotoxin but not by hexamethonium or atropine. Importantly, the OT-induced colonic smooth muscle contraction was decreased significantly in the KO mice relative to WT. The OT receptor expression of colon was detected in colonic myenteric plexus of mice. Central 5-HT is involved in the modulation of colonic motility which may modulate through its regulation of OT synthesis in the hypothalamus. Our results reveal a central 5-HT - hypothalamus OT - colonic OT receptor axis, providing a new target for the treatment of brain-gut dysfunction.

Sinorhizobium meliloti Functionally Replaces 3-Oxoacyl-Acyl Carrier Protein Reductase (FabG) by Overexpressing NodG During Fatty Acid Synthesis.

In Sinorhizobium meliloti, the nodG gene is located in the nodFEG operon of the symbiotic plasmid. Although strong sequence similarity (53% amino acid identities) between S. meliloti NodG and Escherichia coli FabG was reported in 1992, it has not been determined whether S. meliloti NodG plays a role in fatty acid synthesis. We report that expression of S. meliloti NodG restores the growth of the E. coli fabG temperature-sensitive mutant CL104 under nonpermissive conditions. Using in vitro assays, we demonstrated that NodG is able to catalyze the reduction of the 3-oxoacyl-ACP intermediates in E. coli fatty acid synthetic reaction. Moreover, although deletion of the S. meliloti nodG gene does not cause any growth defects, upon overexpression of nodG from a plasmid, the S. meliloti fabG gene encoding the canonical 3-oxoacyl-ACP reductase (OAR) can be disrupted without any effects on growth or fatty acid composition. This indicates that S. meliloti nodG encodes an OAR and can play a role in fatty acid synthesis when expressed at sufficiently high levels. Thus, a bacterium can simultaneously possess two or more OARs that can play a role in fatty acid synthesis. Our data also showed that, although SmnodG increases alfalfa nodulation efficiency, it is not essential for alfalfa nodulation.

Ralstonia solanacearum fatty acid composition is determined by interaction of two 3-ketoacyl-acyl carrier protein reductases encoded on separate replicons.

BACKGROUND: FabG is the only known enzyme that catalyzes reduction of the 3-ketoacyl-ACP intermediates of bacterial fatty acid synthetic pathways. However, there are two Ralstonia solanacearum genes, RSc1052 (fabG1) and RSp0359 (fabG2), annotated as encoding putative 3-ketoacyl-ACP reductases. Both FabG homologues possess the conserved catalytic triad and the N-terminal cofactor binding sequence of the short chain dehydrogenase/reductase (SDR) family. Thus, it seems reasonable to hypothesize that RsfabG1 and RsfabG2 both encode functional 3-ketoacyl-ACP reductases and play important roles in R. solanacearum fatty acid synthesis and growth. METHODS: Complementation of Escherichia coli fabG temperature-sensitive mutant with R. solanacearum fabGs encoded plasmids was carried out to test the function of RsfabGs in fatty acid biosynthesis. RsFabGs proteins were purified by nickel chelate chromatography and fatty acid biosynthetic reaction was reconstituted to investigate the 3-ketoacyl-ACP reductase activity of RsFabGs in vitro. Disruption of both RsfabG genes was done via DNA homologous recombination to test the function of both RsfabG in vivo. And more we also carried out pathogenicity tests on tomato plants using RsfabG mutant strains.  RESULTS: We report that expression of either of the two proteins (RsFabG1 and RsFabG2) restores growth of the E. coli fabG temperature-sensitive mutant CL104 under non-permissive conditions. In vitro assays demonstrate that both proteins restore fatty acid synthetic ability to extracts of the E. coli strain. The RsfabG1 gene carried on the R. solanacearum chromosome is essential for growth of the bacterium, as is the case for fabG in E. coli. In contrast, the null mutant strain with the megaplasmid-encoded RsfabG2 gene is viable but has a fatty acid composition that differs significantly from that of the wild type strain. Our study also shows that RsFabG2 plays a role in adaptation to high salt concentration and low pH, and in pathogenesis of disease in tomato plants. CONCLUSION: R. solanacearum encodes two 3-ketoacyl-ACP reductases that both have functions in fatty acid synthesis. We supply the first evidence that, like other enzymes in the bacterial fatty acid biosynthetic pathway, one bacterium may simultaneously possess two or more 3-oxoacyl-ACP reductase isozymes.

Safety and efficacy of a novel disposable sheathed gastroscopic system in clinical practice.

BACKGROUND AND AIM: Endoscopic examinations carry a potential risk of cross-infection, and the traditional reprocessing method is time consuming. We evaluated the safety and efficacy of a novel disposable sheathed gastroscope system in clinical practice in comparison with the conventional gastroscope. METHODS: There were two phases in the study. In phase 1, 20 patients with hepatitis B were randomized into two groups: the sheathed group was examined with the novel disposable sheathed gastroscope (n = 10) and the conventional group with the conventional gastroscope (n = 10). Microbiologic tests were performed on each endoscope afterwards. In the second phase, 1120 patients were randomized again into the same two groups with 568 and 552 patients in the sheathed group and the conventional group, respectively. The time duration of the endoscopic procedure and reprocessing were measured. The pathology detection rate of endoscopic examinations, the patients' subjective feelings, and problems occurred during procedures were also recorded. RESULTS: The total instrument turn-around time in the phase 2 sheathed group (9.9 ± 1.3 min) was significantly shorter than the conventional group (39.0 ± 1.4 min, P = 0.000). The mean procedural time was slightly longer in the sheathed group than in the conventional group (4.9 ± 1.4 vs 4.1 ± 1.3 min, P = 0.000). However, the duration of endoscopic reprocessing was much shorter (4.9 ± 0.2 vs 35 ± 0.2 min, P = 0.000). No significant differences were observed in patient discomfort, optical clarity, or pathology detection rate. There were no complications in either group, and no microbial contamination was detected in phase 1 of the study. CONCLUSIONS: Compared with the conventional gastroscope, the novel disposable sheathed gastroendoscope is safe and more efficient in clinical practice.

Synthesis, molecular docking and evaluation of thiazolyl-pyrazoline derivatives containing benzodioxole as potential anticancer agents.

A series of novel thiazolyl-pyrazoline derivatives containing benzodioxole (C1-C20) have been designed and synthesized. Among of the synthesized compounds, 2-(5-(benzo[d][1,3]dioxol-5-yl)-3-(4-bromophenyl)-4,5-dihydro-1H-pyrazol-1-yl)-4-(4-bromophenyl)thiazole (C6) displayed the most potent inhibitory activity for HER-2 (IC(50) = 0.18 µM for HER-2). Antiproliferative assay results indicated that compound C6 owned high antiproliferative activity against MCF-7 and B16-F10 in vitro, with IC(50) value of 0.09 and 0.12 µM, respectively, being comparable with the positive control Erlotinib. Docking simulation was further performed to determine the probable binding model. Based on the preliminary results, compound C6 with potent inhibitory activity in tumor growth would be a potential anticancer agent.

[Immunogenicity and safety of a booster dose of inactivated polio vaccine].

OBJECTIVE: To evaluate the immunogenicity and safety of a boost dose of inactivated polio vaccine (IPV) among children aged 18 months who had been administered with primary doses of IPV. METHODS: Form 2011 to 2012, a total of 97 children were enrolled in the present study who were vaccinated with IPV at 2, 3, 4 months of age and boosted with the same vaccine at 18 months of age. Anti-poliovirus neutralizing antibody titers in serum were measured before and after booster vaccination, geometric mean titers (GMT) and seroprotection rate were calculated. Adverse events occurring within 30 days after booster vaccination were observed, including pain, redness/swelling and induration at the injection site, fever, vomit, abnormal crying, drowsiness, loss of appetite, irritability, and all other physical discomfort and related medications were also recorded. A descriptive analysis was performed for the safety assessment. RESULTS: Immunogenicity was assessed in 84 subjects. The pre-booster seropositivity rates of neutralizing antibody against poliovirus type 1, 2, 3 before booster were all 100% (84/84) and the corresponding GMT (95% CI) was 1: 148.5 (116.49-189.29) , 1: 237.68 (178.39-316.67) and 1: 231.87 (181.27-296.58) , respectively. The seropositivity rates of neutralizing antibody against the three types of poliovirus after booster were all 100% (84/84) and the corresponding GMT (95% CI) was 1: 1612.14 (1470.57-1767.34) , 1: 1854.92 (1715.83-2005.29) and 1: 1625.50 (1452.12-1819.58) , respectively. The pre-booster titer of neutralizing antibody against poliovirus type 1, 2, 3 mainly ranged 1: 128-1: 512, which accounted for 65% (55/84) , 55% (46/84) , 74% (62/84) in each type. After the booster immunization, titers of neutralizing antibody against type 1, 2, 3 were increased as subjects with titer ≥ 1: 1024 accounted for 94% (78/84) , 95% (80/84) , 92% (77/84) , respectively.Safety was evaluated in 96 subjects, of which 16 subjects reported adverse events with the rate of 17%. The observed local events were mainly tenderness 3% (3/96) , redness/swelling and induration were not reported. The systemic adverse events included loss of appetite (8%, 8/96) , irritability (8%, 8/96) , fever (7%, 7/96) , abnormal crying (6%, 6/96) , drowsiness (6%, 6/96) and vomit (1%, 1/96) . All reported adverse events were mild or moderate. All of the local events occurred in the day of vaccination and lasted for 1-2 days, while systemic events almost developed within 2 days after vaccination and last less than 3 days. CONCLUSION: IPV booster dose has good immunogenicity and safety profile, which provides effective protection against poliovirus.

[Safety of different sequential immunization schedules of inactivated poliovirus vaccine and oral poliovirus vaccine primary vaccination].

OBJECTIVE: To evaluate safety of different sequential immunization schedules of inactivated poliovirus vaccine (IPV) and oral poliovirus vaccine (OPV) primary vaccination. METHODS: Infants of 2 months old (60-89 days) selected in Beijing, were assigned to four groups, 1 dose IPV plus 2 doses OPV (I-O-O), 2 doses IPV plus 1 dose OPV(I-I-O), 3 doses IPV (I-I-I), and 3 doses OPV (O-O-O), and were vaccinated at the age of 2, 3, 4 months, from 2009 to 2011. The frequencies of systemic as well as local injection site reactions after every dose were recorded and calculated. A total of 553 infants were enrolled in the study and 89 infants were quit, 1492 diseases were observed. RESULTS: The incidence of adverse events in I-O-O, I-I-O, I-I-I, O-O-O were 22.9% (94/410), 18.4% (60/327), 22.0% (78/354) and 17.7% (71/401) with no statistical differences (χ(2) = 4.84, P = 0.184). Dose 1 (22.7% (32/141)-35.3% (54/153) ) was more frequently than dose 2 and dose 3. No serious adverse events (SAE) were reported during the study. The incidence of systemic adverse reactions in I-O-O, I-I-O, I-I-I, O-O-O were 21.5% (88/410), 17.7% (58/327) , 20.1% (71/354) and 17.7% (71/401) with no statistical differences (χ(2) = 2.53, P = 0.472). Abnormal crying were the most frequency reactions (7.2% (29/401)-11.3% (37/327) ) in 4 groups. Rarely severe reactions were observed of abnormal crying, somnolence, irritability and mild or medium reactions occurred in other symptoms. Local adverse reactions such as injection site pain, scleroma and swelling were reported by 2.2% (5/229)-5.6% (22/393) ,0-0.9% (2/229) and 0-1.0% (4/393) in I-O-O,I-I-O and I-I-I, and most reactions were mild. CONCLUSION: Three IPV immunization and IPV/OPV sequential immunization as well as three OPV immunization demonstrated safe.

Novel mandelic acid derivatives suppress virulence of Ralstonia solanacearum via type III secretion system.

BACKGROUND: Bacterial wilt induced by Ralstonia solanacearum is regarded as one of the most devastating diseases. However, excessive and repeated use of the same bactericides has resulted in development of bacterial resistance. Targeting bacterial virulence factors, such as type III secretion system (T3SS), without inhibiting bacterial growth is a possible assay to discover new antimicrobial agents. RESULTS: In this work, identifying new T3SS inhibitors, a series of mandelic acid derivatives with 2-mercapto-1,3,4-thiazole moiety was synthesized. One of them, F-24, inhibited the transcription of hrpY gene significantly. The presence of this compound obviously attenuated hypersensitive response (HR) without inhibiting bacterial growth of R. solanacearum. The transcription levels of those typical T3SS genes were reduced to various degrees. The test of the ability of F-24 in protecting plants demonstrated that F-24 protected tomato plants against bacterial wilt without restricting the multiplication of R. solanacearum. The mechanism of this T3SS inhibition is through the PhcR-PhcA-PrhG-HrpB pathway. CONCULSION: The screened F-24 could inhibit R. solanacearum T3SS and showed better inhibitory activity than previously reported inhibitors without affecting the growth of the strain, and F-24 is a compound with good potential in the control of R. solanacearum. © 2023 Society of Chemical Industry.

Quorum quenching by a type IVA secretion system effector.

Proteobacteria primarily utilize acyl-homoserine lactones (AHLs) as quorum-sensing signals for intra-/interspecies communication to control pathogen infections. Enzymatic degradation of AHL represents the major quorum-quenching mechanism that has been developed as a promising approach to prevent bacterial infections. Here we identified a novel quorum-quenching mechanism revealed by an effector of the type IVA secretion system (T4ASS) in bacterial interspecies competition. We found that the soil antifungal bacterium Lysobacter enzymogenes OH11 (OH11) could use T4ASS to deliver the effector protein Le1288 into the cytoplasm of another soil microbiome bacterium Pseudomonas fluorescens 2P24 (2P24). Le1288 did not degrade AHL, whereas its delivery to strain 2P24 significantly impaired AHL production through binding to the AHL synthase PcoI. Therefore, we defined Le1288 as LqqE1 (Lysobacter quorum-quenching effector 1). Formation of the LqqE1-PcoI complex enabled LqqE1 to block the ability of PcoI to recognize/bind S-adenosy-L-methionine, a substrate required for AHL synthesis. This LqqE1-triggered interspecies quorum-quenching in bacteria seemed to be of key ecological significance, as it conferred strain OH11 a better competitive advantage in killing strain 2P24 via cell-to-cell contact. This novel quorum-quenching also appeared to be adopted by other T4ASS-production bacteria. Our findings suggest a novel quorum-quenching that occurred naturally in bacterial interspecies interactions within the soil microbiome by effector translocation. Finally, we presented two case studies showing the application potential of LqqE1 to block AHL signaling in the human pathogen Pseudomonas aeruginosa and the plant pathogen Ralstonia solanacearum.

Novel pyrimidin-4-one derivatives as potential T3SS inhibitors against Xanthomonas campestris pv. campestris.

BACKGROUND: Cruciferous black rot is caused by Xanthomonas campestris pv. campestris (Xcc) infection and is a widespread disease worldwide. Excessive and repeated use of bactericide is an important cause of the development of bacterial resistance. It is imperative to take new approaches to screening compounds that target virulence factors rather than kill bacterial pathogens. The type III secretion system (T3SS) invades a variety of cells by transporting virulence effector factors into the cytoplasm and is an attractive antitoxic target. Toward the search of new T3SS inhibitors, an alternative series of novel pyrimidin-4-one derivatives were designed and synthesized and assessed for their effect in blocking the virulence. RESULTS: All of the target compounds were characterized by proton (1 H) nuclear magnetic resonance (NMR), carbon-13 (13 C) NMR, fluorine-19 (19 F) NMR and high-resolution mass spectrometry (HRMS). All compounds were evaluated using high-throughput screening systems against Xcc. The results of the biological activity test revealed that the compound SPF-9 could highly inhibit the activity of xopN gene promoter and the hypersensitivity (HR) of tobacco without affecting bacterial growth. Moreover, messenger RNA (mRNA) level measurements showed that compound SPF-9 inhibited the expression of some representative genes (hrp/hrc genes). Compound SPF-9 weakened the pathogenicity of Xcc to Raphanus sativus L. CONCLUSION: Compound SPF-9 has good potential for further development as a novel T3SS inhibitor against Xcc. © 2023 Society of Chemical Industry.

Clinical guideline on magnetically controlled capsule gastroscopy (2021 edition).

With the development and generalization of endoscopic technology and screening, clinical application of magnetically controlled capsule gastroscopy (MCCG) has been increasing. In recent years, various types of MCCG are used globally. Therefore, establishing relevant guidelines on MCCG is of great significance. The current guidelines containing 23 statements were established based on clinical evidence and expert opinions, mainly focus on aspects including definition and diagnostic accuracy, application population, technical optimization, inspection process, and quality control of MCCG. The level of evidence and strength of recommendations were evaluated. The guidelines are expected to guide the standardized application and scientific innovation of MCCG for the reference of clinicians.

Synthesis, biological evaluation and molecular modeling of dihydro-pyrazolyl-thiazolinone derivatives as potential COX-2 inhibitors.

A series of dihydro-pyrazolyl-thiazolinone derivatives (5a-5t) have been synthesized and their biological activities were also evaluated as potential cyclooxygenase-2 (COX-2) inhibitors. Among these compounds, compound 2-(3-(3,4-dimethylphenyl)-5-phenyl-4,5-dihydro-1H-pyrazol-1-yl)thiazol-4(5H)-one (5a) displayed the most potent COX-2 inhibitory activity with IC(50) of 0.5µM, but weak to COX-1. Docking simulation was performed to position compound 5a into the COX-2 active site to determine the probable binding model. Based on the preliminary results, compound 5a with potent inhibitory activity and low toxicity would be a potential and selective anti-cyclooxygenase-2 agent.