Albiflorin alleviates neuroinflammation of rats after MCAO via PGK1/Nrf2/HO-1 signaling pathway.

Ischemic stroke is acknowledged as one of the most frequent causes of death and disability, in which neuroinflammation plays a critical role. Emerging evidence supports that the PGK1/Nrf2/HO-1 signaling can modulate inflammation and oxidative injury. Albiflorin (ALB), a main component of Radix paeoniae Alba, possesses anti-inflammatory and antioxidative properties. However, how it exerts a protective role still needs further exploration. In our study, the middle cerebral artery occlusion (MCAO) model was established, and the Longa score was applied to investigate the degree of neurological impairment. Dihydroethidium (DHE) staining and Malondialdehyde (MDA) assay were used to detect the level of lipid peroxidation. 2, 3, 5-Triphenyltetrazolium chloride (TTC) staining was used to measure the infarct area. Evans blue staining was employed to observe the integrality of the blood-brain barrier (BBB). The injury of brain tissue in each group was observed via HE staining. Immunofluorescence staining, enzyme-linked immunosorbent assay (ELISA) and western blot assay were used for the measurement of inflammatory factors and protein levels. We finally observed that ALB relieved cerebral infarction symptoms, attenuated oxidative damage in brain tissues, and reduced neuroinflammation and cell injury in MCAO rats. The overexpression of PGK1 abrogated the protective effect of ALB after experimental cerebral infarction. ALB promoted PGK1 degradation and induced Nrf2 signaling cascade activation for subsequent anti-inflammatory and antioxidant damage. Generally speaking, ALB exerted a protective role in treating cerebral ischemia, and it might target at PGK1/Nrf2/HO-1 signaling. Thus, ALB might be a potential therapeutic agent to alleviate neuroinflammation and protect brain cells after cerebral infarction.

[Filamentous morphology: a new frontier for genetic modification of filamentous fungal cell factories].

Filamentous fungi are a group of eukaryotic microorganisms widely found in nature. Some filamentous fungi have been developed as "cell factories" and extensively used for the production of recombinant proteins, organic acids, and secondary metabolites due to their strong protein secretion capabilities or effective synthesis of many natural products. The growth morphology of filamentous fungi significantly influences the quality and quantity of fermented products. Previous research conducted by the authors' group revealed that an increase in hyphal branches leads to enhanced protein secretion during liquid fermentation. With the development of morphological engineering of filamentous fungi, an increasing number of studies have focused on modifying fungal mycelium morphology to improve the yield of target metabolites during fermentation. While there have been a few reviews on the relationship between fungal fermentation morphology and productivity, research in this area is rapidly developing and requires updates. The paper presents a comprehensive review of domestic and international research reports, along with the authors' own research findings, to systematically review the morphological patterns of filamentous fungi, the impact of fungal morphology on industrial fermentation, as well as methods and strategies for regulating mycelial morphology. The aim of this review is to enhance the understanding of relevant domestic scholars regarding the morphological development of filamentous fungi and provide ideas for the rational engineering of fungal strains suitable for industrial fermentation.

Total ankle replacement versus ankle fusion for end-stage ankle arthritis: A meta-analysis.

PURPOSE: This study aims to systematically review the efficacy and safety of total ankle replacement (TAR) and ankle fusion (AF) as treatment options for end-stage ankle arthritis. METHODS: A comprehensive literature search was conducted on data from multiple databases, including PubMed, The Cochrane Library, Construction and Building Materials, Embase, Web of Science, and Scopus for RCTs and prospective cohort studies comparing TAR and AF in patients with end-stage ankle arthritis from inception up to June, 2023. Our primary outcomes of interest included patients' clinical function scores and complications. We employed Review Manager 5.4 and Stata/MP 14.0 software for the meta-analysis. RESULTS: Our analysis incorporated 13 comparative studies, including 11 prospective studies, one pilot RCT, and one RCT. The pooled results revealed no significant difference in postoperative Short Form-36 scores between the TAR and AF groups (MD = -1.19, 95% CI: -3.89 to 1.50, p = .39). However, the postoperative Foot and Ankle Ability Measure scores in the AF group were significantly higher than in the TAR group (MD = 8.30, 95% CI: 1.01-15.60, p = .03). There was no significant difference in postoperative complication rates between the TAR and AF groups (RR = 0.95, 95% CI: 0.59 to 1.54, p = .85). CONCLUSION: Currently available evidence suggests no significant disparity in postoperative outcomes between TAR and AF. In the short term, TAR demonstrates better clinical scores than AF and lower complication rates. Conversely, in the long term, AF exhibits superior clinical scores and lower complication rates, although this difference is not statistically significant.

Huangqi Guizhi Wuwu decoction promotes M2 microglia polarization and synaptic plasticity via Sirt1/NF-κB/NLRP3 pathway in MCAO rats.

Huangqi Guizhi Wuwu decoction (HGWD) has been demonstrated to ameliorate cerebral ischemia-reperfusion injury in clinical application. Nevertheless, the exact mechanisms of HGWD have not been conclusively elucidated. This study aimed to investigate the potential role and mechanism of HGWD on neurological deficits in a rat model of middle cerebral artery occlusion (MCAO). Our results showed that HGWD significantly alleviated neurological deficits in MCAO rats, evidenced by high mNSS score, reduced cerebral infarction area, and improved brain pathological injury. Besides, HGWD reduced the levels of TNF-α, IL-1ß, IL-6, SOD, MDA and GSH in the brain tissue. Further study suggested that HGWD promoted microglia polarization towards M2 by inhibiting M1 activation (Iba1+/CD16+, iNOS) and enhancing M2 activation (Iba1+/CD206+, Arg-1). Additionally, HGWD increased dendritic spine density and enhanced levels of synapse marker proteins (PSD95, Synapsin I). HGWD also up-regulated Sirt1 expression while inhibited p-NF-κB, NLRP3, ASC, and cleaved caspase-1 level in the hippocampus of MCAO rats. Sirt1 specific inhibitor EX527 notably weakened the neuroprotective efficacy of HGWD against cerebral ischemia, and significantly abolished its modulation on microglia polarization and synaptic plasticity in vivo. Collectively, our findings suggested that HGWD ameliorated neuronal injury in ischemic stroke by modulating M2 microglia polarization and synaptic plasticity, at least partially, via regulating Sirt1/NF-κB/NLRP3 pathway, further supporting HGWD as a potential therapy for neuroprotection after ischemic stroke.

Importin ß1 Mediates Nuclear Entry of EIN2C to Confer the Phloem-Based Defense against Aphids.

Ethylene Insensitive 2 (EIN2) is an integral membrane protein that regulates ethylene signaling towards plant development and immunity by release of its carboxy-terminal functional portion (EIN2C) into the nucleus. The present study elucidates that the nuclear trafficking of EIN2C is induced by importin ß1, which triggers the phloem-based defense (PBD) against aphid infestations in Arabidopsis. In plants, IMPß1 interacts with EIN2C to facilitate EIN2C trafficking into the nucleus, either by ethylene treatment or by green peach aphid infestation, to confer EIN2-dependent PBD responses, which, in turn, impede the phloem-feeding activity and massive infestation by the aphid. In Arabidopsis, moreover, constitutively expressed EIN2C can complement the impß1 mutant regarding EIN2C localization to the plant nucleus and the subsequent PBD development in the concomitant presence of IMPß1 and ethylene. As a result, the phloem-feeding activity and massive infestation by green peach aphid were highly inhibited, indicating the potential value of EIN2C in protecting plants from insect attacks.

Characterization of two multidrug-resistant Klebsiella pneumoniae harboring tigecycline-resistant gene tet(X4) in China.

Objectives: Tigecycline is recognized as one of the last-line antibiotics to treat serious bacterial infection caused by carbapenem-resistant Klebsiella pneumoniae (CRKP). The plasmid-borne gene tet(X4) mediates high resistance to tigecycline. However, the prevalence and genetic context of tet(X4) in K. pneumoniae from various sources are not fully understood. Here, we investigated the prevalence of tet(X4)-positive K. pneumoniae and characterized the genetic context of tet(X4)-bearing plasmids in K. pneumoniae isolates. Methods: Polymerase chain reaction (PCR) was used to detect the tet(X4) gene. The transferability of the tet(X4)-carrying plasmids was tested by conjugation assays. The Galleria mellonella infection model was used to test virulence of tet(X4)-positive strains. Whole-genome sequencing and genome-wide analysis were performed to identify the antimicrobial resistance and the virulence genes, and to clarify the genetic characteristics of the tet(X4)-positive isolates. Results: Among 921 samples, we identified two tet(X4)-positive K. pneumoniae strains collected from nasal swabs of two pigs (0.22%, 2/921). The two tet(X4)-positive isolates exhibited high minimum inhibitory concentrations to tigecycline (32-256 mg/L) and tetracycline (256 mg/L). The plasmids carrying the tet(X4) gene can transfer from the donor strain K. pneumoniae to the recipient strain Escherichia coli J53. Genetic analysis of the complete sequence of two tet(X4)-carrying plasmids pTKPN_3-186k-tetX4 and pTKPN_8-216k-tetX4 disclosed that the tet(X4) gene was flanked by delta ISCR2 and IS1R, which may mediate the transmission of the tet(X4) gene. Conclusion: The prevalence of tet(X4)-positive K. pneumoniae among different sources was low. ISCR2 and IS1R may contribute to the horizontal transfer of tet(X4) gene. Effective measures should be taken to prevent the transmission of tet(X4)-producing K. pneumoniae in humans or animals.

MYB44 regulates PTI by promoting the expression of EIN2 and MPK3/6 in Arabidopsis.

The plant signaling pathway that regulates pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) involves mitogen-activated protein kinase (MAPK) cascades that comprise sequential activation of several protein kinases and the ensuing phosphorylation of MAPKs, which activate transcription factors (TFs) to promote downstream defense responses. To identify plant TFs that regulate MAPKs, we investigated TF-defective mutants of Arabidopsis thaliana and identified MYB44 as an essential constituent of the PTI pathway. MYB44 confers resistance against the bacterial pathogen Pseudomonas syringae by cooperating with MPK3 and MPK6. Under PAMP treatment, MYB44 binds to the promoters of MPK3 and MPK6 to activate their expression, leading to phosphorylation of MPK3 and MPK6 proteins. In turn, phosphorylated MPK3 and MPK6 phosphorylate MYB44 in a functionally redundant manner, thus enabling MYB44 to activate MPK3 and MPK6 expression and further activate downstream defense responses. Activation of defense responses has also been attributed to activation of EIN2 transcription by MYB44, which has previously been shown to affect PAMP recognition and PTI development. AtMYB44 thus functions as an integral component of the PTI pathway by connecting transcriptional and posttranscriptional regulation of the MPK3/6 cascade.

Novel Human Meningioma Organoids Recapitulate the Aggressiveness of the Initiating Cell Subpopulations Identified by ScRNA-Seq.

High-grade meningioma has an unsatisfactory outcome despite surgery and postoperative radiotherapy; however, the factors driving its malignancy and recurrence remain largely unknown, which limits the development of systemic treatments. Single-cell RNA sequencing (scRNA-Seq) technology is a powerful tool for studying intratumoral cellular heterogeneity and revealing the roles of various cell types in oncogenesis. In this study, scRNA-Seq is used to identify a unique initiating cell subpopulation (SULT1E1+ ) in high-grade meningiomas. This subpopulation modulates the polarization of M2-type macrophages and promotes meningioma progression and recurrence. A novel patient-derived meningioma organoid (MO) model is established to characterize this unique subpopulation. The resulting MOs fully retain the aggressiveness of SULT1E1+ and exhibit invasiveness in the brain after orthotopic transplantation. By targeting SULT1E1+ in MOs, the synthetic compound SRT1720 is identified as a potential agent for systemic treatment and radiation sensitization. These findings shed light on the mechanism underlying the malignancy of high-grade meningiomas and provide a novel therapeutic target for refractory high-grade meningioma.

Identification of Two CDK5R1-Related Subtypes and Characterization of Immune Infiltrates in Alzheimer's Disease Based on an Integrated Bioinformatics Analysis.

Background: Alzheimer's disease (AD) is a neurodegenerative disorder and the major cause of senile dementia. The Reelin pathway has been involved in both learning and AD pathogenesis. However, the specific Reelin-related gene signature during the pathological process remains unknown. Methods: Reelin-related gene (CDK5R1) expression was analyzed using the GEO datasets. The relevant genes of CDK5R1 were identified using differential expression analysis and weighted gene correlation network analysis (WGCNA) based on the GSE43850 dataset. ConsensusClusterPlus analysis was applied to identify subtypes (C1 and C2) of AD. The CIBERSORT algorithm was used to assess the immune cell infiltration between the two AD subtypes. Results: CDK5R1 was downregulated in AD. 244 differentially expressed CDK5R1-related genes (DECRGs) between the two subgroups were mainly enriched in GABAergic synapse, neuroactive ligand-receptor interaction, synapse organization, neurotransmitter transport, etc. Furthermore, the GSVA results indicated that immune-related pathways were significantly enriched in the C1 subgroup. Interestingly, 10 Reelin pathway-related genes (CRK, DAB2IP, LRP8, RELN, STAT5A, CDK5, CDK5R1, DAB1, FYN, and SH3KBP1) were abnormally expressed between the two subgroups. The proportion of T cell gamma delta, monocytes, macrophage M2, and dendritic cells activated decreased from C1 to C2, while the proportion of plasma cells, T cell follicular helper, and NK cells activated increased. Conclusion: Two CDK5R1-related subtypes of AD were identified, helping us to better understand the role of CDK5R1 in the pathological process of AD.

Effects of Various Marine Toxins on the Mouse Intestine Organoid Model.

Because of their trace existence, exquisite structure and unique role, highly toxic marine biotoxins have always led to the development of natural product identification, structure and function research, chemistry and biosynthesis, and there are still many deficiencies in the injury and protection of highly toxic organisms, toxin biosynthesis, rapid detection, poisoning and diagnosis and treatment. In this study, a mouse intestine organoid (MIO) model was constructed to explore the effects of the marine toxins okadaic acid (OA) and conotoxin (CgTx) on MIO. The results showed that the cell mortality caused by the two toxins at middle and high concentrations was significantly higher than the cell mortality of the control group, the ATPase activity in each group exposed to OA was significantly lower than the ATPase activity of the control group, all the CgTx groups were significantly higher than that of the control group, and the number of apoptotic cells was not significantly higher than the number of apoptotic cells of the control group. Through RNA-Seq differential genes, Gene Ontology (GO) and pathway analysis, and Gene Set Enrichment Analysis (GSEA) experimental results, it was demonstrated that OA reduced cell metabolism and energy production by affecting cell transcription in MIO. Ultimately, cell death resulted. In contrast, CgTx upregulated the intracellular hormone metabolism pathway by affecting the nuclear receptor pathway of MIO, which resulted in cell death and the generation of energy in large amounts.

Molecular Hydrogen Reduces Electromagnetic Pulse-Induced Male Rat Reproductive System Damage in a Rodent Model.

Infertility has got to be a broadly concerned social issue these days, in which the malefactor cannot be overlooked. Numerous studies have shown that electromagnetic pulse (EMP) radiation may have seriously damaging effects on reproductive health, through nonthermal effects and oxidative stress. Molecular hydrogen, a selective hydroxyl radical scavenger, explains the protective effects against many diseases closely associated with oxidative damage, such as ionizing radiation (IR). We sought to characterize the beneficial effects of molecular hydrogen on the male reproductive system in a rodent EMP exposure model. The 8-week-old male Sprague-Dawley rats were exposed to EMP (peak intensity 1000 kV/m, pulse edge 20 ns, pulse width 200 ns, 1 Hz, and 200 pulses), with or without hydrogen-rich water. The pathological structure of the testis, the rate of apoptosis of the testis, the serum testosterone level, the sperm parameters, and the activity of the antioxidant enzymes of the testis were measured. Then, transcriptomic and untargeted metabolomic analyses were applied to uncover the underlying mechanism. Exposure to EMP increased testicular apoptosis rate and apoptosis protein level, decreased sperm viability and motility, decreased serum testosterone levels, and diminished testicular antioxidant capacity. Molecular hydrogen-alleviated damage decreased the testicular apoptosis rate and apoptosis protein level, increased sperm motility, increased serum testosterone levels, and improved antioxidative capacity. Omics results showed that molecular hydrogen has a strong influence on metabolic pathways, and EMP affects mainly oxidative phosphorylation, TNF signaling pathways, and cytokine-receptor interactions. The mechanism of molecular hydrogen's effect may be related to the reversal of some metabolite levels. These observations warrant molecular hydrogen as an innovative approach for potential protection against EMP.

Genome-wide DNA methylation profiles and small noncoding RNA signatures in sperm with a high DNA fragmentation index.

BACKGROUND: A growing number of studies have reported that sperm DNA fragmentation (SDF) is associated with male infertility. However, no studies have compared genome-wide DNA methylation profiles and sncRNA signatures between sperm with high and low sperm DNA fragmentation indices (DFIs). METHODS: Whole-genome bisulfite sequencing (WGBS) was performed on sperm samples from a weak group (DFI ≥ 30%, n = 6) and normal group (DFI ≤ 15%, n = 7). Small noncoding RNA (sncRNA) deep sequencing was conducted for sperm samples from the weak (DFI ≥ 30%, n = 13) and normal (DFI ≤ 15%, n = 17) groups. RESULTS: A total of 4939 differentially methylated regions (DMRs) were identified in the weak group sperm samples relative to normal group sperm samples, with 2072 (41.95%) of them located in promoter regions. The percentages of hypermethylated DMRs were higher than those of hypomethylated DMRs in all seven examined gene annotation groups. Hypermethylated DMRs were significantly enriched in terms associated with neurons and microtubules. Compared with the normal group, the global DNA methylation level of the weak group sperm showed a downward trend, with lower correlation for methylation in the weak group sperm; therefore, the chromosomes of high-DFI sperm may be loose. On average, 40.5% of sncRNAs were annotated as rsRNAs, 19.3% as tsRNAs, 10.4% as yRNAs, and 7.1% as miRNAs. A total of 27 miRNAs, 151 tsRNAs, and 70 rsRNAs were differentially expressed between the two groups of sperm samples. Finally, 7 sncRNAs were identified as candidate sperm quality biomarkers, and the target genes of the differentially expressed miRNAs are involved in nervous system development. CONCLUSION: Our findings suggest that genome-wide DNA methylation profiles and sncRNA signatures are significantly altered in high-DFI sperm. Our study provides potential biomarkers for sperm quality.

Phosphorylation of a wheat aquaporin at two sites enhances both plant growth and defense.

Eukaryotic aquaporins share the characteristic of functional multiplicity in transporting distinct substrates and regulating various processes, but the underlying molecular basis for this is largely unknown. Here, we report that the wheat (Triticum aestivum) aquaporin TaPIP2;10 undergoes phosphorylation to promote photosynthesis and productivity and to confer innate immunity against pathogens and a generalist aphid pest. In response to elevated atmospheric CO2 concentrations, TaPIP2;10 is phosphorylated at the serine residue S280 and thereafter transports CO2 into wheat cells, resulting in enhanced photosynthesis and increased grain yield. In response to apoplastic H2O2 induced by pathogen or insect attacks, TaPIP2;10 is phosphorylated at S121 and this phosphorylated form transports H2O2 into the cytoplasm, where H2O2 intensifies host defenses, restricting further attacks. Wheat resistance and grain yield could be simultaneously increased by TaPIP2;10 overexpression or by expressing a TaPIP2;10 phosphomimic with aspartic acid substitutions at S121 and S280, thereby improving both crop productivity and immunity.

Benzene Exposure Leads to Lipodystrophy and Alters Endocrine Activity In Vivo and In Vitro.

Benzene is a ubiquitous pollutant and mainly accumulates in adipose tissue which has important roles in metabolic diseases. The latest studies reported that benzene exposure was associated with many metabolic disorders, while the effect of benzene exposure on adipose tissue remains unclear. We sought to investigate the effect using in vivo and in vitro experiments. Male adult C57BL/6J mice were exposed to benzene at 0, 1, 10 and 100 mg/kg body weight by intragastric gavage for 4 weeks. Mature adipocytes from 3T3-L1 cells were exposed to hydroquinone (HQ) at 0, 1, 5 and 25 µM for 24 hours. Besides the routine hematotoxicity, animal experiments also displayed significant body fat content decrease from 1 mg/kg. Interestingly, the circulating non-esterified fatty acid (NEFA) level increased from the lowest dose (ptrend < 0.05). Subsequent analysis indicated that body fat content decrease may be due to atrophy of white adipose tissue (WAT) upon benzene exposure. The average adipocyte area of WAT decreased significantly even from 1 mg/kg with no significant changes in total number of adipocytes. The percentages of small and large adipocytes in WAT began to significantly increase or decrease from 1 mg/kg (all p < 0.05), respectively. Critical genes involved in lipogenesis and lipolysis were dysregulated, which may account for the disruption of lipid homeostasis. The endocrine function of WAT was also disordered, manifested as significant decrease in adipokine levels, especially the leptin. In vitro cell experiments displayed similar findings in decreased fat content, dysregulated critical lipid metabolism genes, and disturbed endocrine function of adipocytes after HQ treatment. Pearson correlation analysis showed positive correlations between white blood cell (WBC) count with WAT fat content and plasma leptin level (r = 0.330, 0.344, both p < 0.05). This study shed light on the novel aspect that benzene exposure could induce lipodystrophy and disturb endocrine function of WAT, and the altered physiology of WAT might in turn affect benzene-induced hematotoxicity and metabolic disorders. The study provided new insight into understanding benzene-induced toxicity and the relationship between benzene and adipose tissue.

First case report of complete paternal isodisomy of chromosome 10 harbouring a novel variant in COL17A1 that causes junctional epidermolysis bullosa intermediate.

BACKGROUND: Uniparental disomy (UPD) is a condition in which both chromosomes are inherited from the same parent, except for imprinting disorders. Uniparental isodisomy (UPiD) may result in a homozygous variant contributing to an autosomal recessive disorder in the offspring of a heterozygous carrier. Junctional epidermolysis bullosa intermediate (JEB intermediate) is an autosomal recessive inherited disease that is associated with a series of gene variants, including those of COL17A1. CASE PRESENTATION: We report the first case of complete paternal UPiD of chromosome 10 harbouring a novel homozygous variant in COL17A1: c.1880(exon23)delG (p.G627Afs*56). This variant led to the clinical phenotype of junctional epidermolysis bullosa intermediate in a 5-year-old child. Trio-whole exome sequencing (Trio-WES) and in silico data analysis were used for variant identification, Sanger sequencing was performed for variant validation, and pathological examination was performed as the gold standard for phenotype confirmation. CONCLUSIONS: We recommend the use of WES as a first-tier test for the diagnosis of epidermolysis bullosa, especially for paediatric patients. Moreover, UPD events should be detected and analysed routinely through WES data in the future.

The regulatory effect of fermented black barley on the gut microbiota and metabolic dysbiosis in mice exposed to cigarette smoke.

Smoking is a global public health event that can cause oxidative stress and gut microbiota dysbiosis and is related to the occurrence of diseases such as cancer and respiratory system disease. We previously found that fermented black barley was rich in antioxidative components such as polyphenols and flavonoids and regulated gut microbiota dysbiosis. In the present study, the protective effects of fermented black barley on cigarette smoke-induced damage, such as lung, reproduction organ injury, gut microbiota and metabolic dysbiosis, were investigated. Fermented black barley (100 µL/10 g·BW per day, containing 1 × 108 CFU/mL Lactobacillus) was administered orally to male ICR mice that were regularly exposed to cigarette smoke (one time a day, 15 cigarettes each time, 30 min/time). The intervention lasted continuously for 12 weeks. The results showed that compared to the group exposed only to cigarette smoke, fermented black barley treatment alleviated the pathological damage to lung and testis tissues and significantly increased the total sperm motility and antioxidative capacity of the lung. Fermented black barley also regulated the intestinal microbiome diversity; reduced the relative abundances of Lactobacillus, Turicibacter and Bifidobacterium; and increased the relative abundances of Oscillospira and Ruminococcus at the genus level. Furthermore, the metabolic profile was investigated via analysis of the abundances of fecal and hepatic metabolites, and it was shown that fermented black barley treatment alleviated the metabolic dysbiosis of lipids, amino acids, and the biosynthesis of steroid hormones (such as dehydroepiandrosterone sulfate, etc.) induced by cigarette smoking, which approached normal conditions. These regulatory effects may partially elucidate the beneficial role of fermented black barley in alleviating the harmful effects of cigarette smoking. In summary, supplementation with fermented cereal food may be a helpful way to ameliorate cigarette smoking-induced damage.

MCR-1-dependent lipid remodelling compromises the viability of Gram-negative bacteria.

The global dissemination of the mobilized colistin resistance gene, mcr-1, threatens human health. Recent studies by our group and others have shown that the withdrawal of colistin as a feed additive dramatically reduced the prevalence of mcr-1. Although it is accepted that the rapid reduction in mcr-1 prevalence may have resulted, to some extent, from the toxic effects of MCR-1, the detailed mechanism remains unclear. Here, we found that MCR-1 damaged the outer membrane (OM) permeability in Escherichia coli and Klebsiella pneumonia and that this event was associated with MCR-1-mediated cell shrinkage and death during the stationary phase. Notably, the capacity of MCR-1-expressing cells for recovery from the stationary phase under improved conditions was reduced in a time-dependent manner. We also showed that mutations in the potential lipid-A-binding pocket of MCR-1, but not in the catalytic domain, restored OM permeability and cell viability. During the stationary phase, PbgA, a sensor of periplasmic lipid-A and LpxC production that performed the first step in lipid-A synthesis, was reduced after MCR-1 expression, suggesting that MCR-1 disrupted lipid homeostasis. Consistent with this, the overexpression of LpxC completely reversed the MCR-1-induced OM permeability defect. We propose that MCR-1 causes lipid remodelling that results in an OM permeability defect, thus compromising the viability of Gram-negative bacteria. These findings extended our understanding of the effect of MCR-1 on bacterial physiology and provided a potential strategy for eliminating drug-resistant bacteria.

Identification of Plasmid-Mediated Tigecycline-Resistant Gene tet(X4) in Enterobacter cloacae from Pigs in China.

Two tet(X4)-positive Enterobacter cloacae isolates TECL_1 and TECL_2 were isolated from pigs in China. S1-PFGE and Southern blotting showed that tet(X4) located on plasmids in the size of ∼290 kb and ∼190 kb in TECL_1 and TECL_2, respectively. Conjugation experiment demonstrated that the tet(X4)-harboring plasmid can transfer from the donor strain TECL_1 and TECL_2 to the recipient strain Escherichia coli J53, and the tigecycline resistance of transconjugants was increased by 128-fold and 64-fold compared with E. coli J53, respectively. We obtained the complete plasmid sequence of pTECL_2-190k-tetX4 (190,185 bp) from E. cloacae TECL_2 and found that the plasmid was a hybrid plasmid with replicon types of IncFIA, IncHI1A and IncHI1B. We further analyzed 85 tet(X4)-carrying plasmids in the public database and clarified that pTECL_2-190k-tetX4-like plasmid was widespread in multiple species of Enterobacteriaceae. IMPORTANCE We identified two tet(X4)-positive E. cloacae isolates, which has not been previously reported. We obtained the complete sequence of pTECL_2-190k-tetX4 and found that it was a hybrid plasmid with multiple replicon types, including IncFIA, IncHI1A and IncHI1B. By comparing all the known tet(X4)-carrying plasmids, we found that pTECL_2-190k-tetX4-like plasmid has been disseminated across various species in China. Our study expanded the identification of tet(X4)-positive species and emphasized that pTECL_2-190k-tetX4-like plasmid has spread widely in various species.

Evaluating the Mode of Antifungal Action of Heat-Stable Antifungal Factor (HSAF) in Neurospora crassa.

Heat-stable antifungal factor (HSAF) isolated from Lysobacter enzymogenes has shown a broad-spectrum of antifungal activities. However, little is known about its mode of action. In this study, we used the model filamentous fungus Neurospora crassa to investigate the antifungal mechanism of HSAF. We first used HSAF to treat the N. crassa strain at different time points. Spore germination, growth phenotype and differential gene expression analysis were conducted by utilizing global transcriptional profiling combined with genetic and physiological analyses. Our data showed that HSAF could significantly inhibit the germination and aerial hyphae growth of N. crassa. RNA-seq analysis showed that a group of genes, associated with cell wall formation and remodeling, were highly activated. Screening of N. crassa gene deletion mutants combined with scanning electron microscopic observation revealed that three fungal cell wall integrity-related genes played an important role in the interaction between N. crassa and L. enzymogens. In addition, Weighted Gene Co-Expression Network Analysis (WGCNA), accompanied by confocal microscopy observation revealed that HSAF could trigger autophagy-mediated degradation and eventually result in cell death in N. crassa. The findings of this work provided new insights into the interactions between the predatory Lysobacter and its fungal prey.

Interfacial Reduction Nucleation of Noble Metal Nanodots on Redox-Active Metal-Organic Frameworks for High-Efficiency Electrocatalytic Conversion of Nitrate to Ammonia.

Electrochemically converting nitrate to ammonia is a promising route to realize artificial nitrogen recycling. However, developing highly efficient electrocatalysts is an ongoing challenge. Herein, we report the construction of stable and redox-active zirconium metal-organic frameworks (Zr-MOFs) based on Zr6 nanoclusters and redox-reversible tetrathiafulvalene (TTF) derivatives as inorganic nodes and organic linkers, respectively. The redox-active Zr-MOF can facilitate the in situ reduction of noble metal precursors free of external reductants and realize the uniform nucleation of noble metal nanodots (NDs) on Zr-MOF, achieving the preparation of M-NDs/Zr-MOF (M = Pd, Ag, or Au). The highly porous Zr-MOF with good conductivity can facilitate the mass transfer process. Among the M-NDs/Zr-MOF catalysts, Pd-NDs/Zr-MOF exhibits the highest electrocatalytic activity, delivering a NH3 yield of 287.31 mmol·h-1·g-1cat. and a Faradaic efficiency of 58.1%. The proposed interfacial reduction nucleation strategy for anchoring M NDs on Zr-MOFs can be applied to other challenging energy conversion reactions.