Type IV pili trigger episymbiotic association of Saccharibacteria with its bacterial host.

Recent characterization of the obligate episymbiont Saccharibacteria (TM7) belonging to the candidate phyla radiation (CPR) has expanded the extent of microbial diversity. However, the episymbiotic lifestyle of TM7 is still underexploited due to the deficiency of cultivated representatives. Here, we describe gene-targeted TM7 cultivation guided by repurposing epicPCR (emulsion, paired isolation, and concatenation PCR) to capture in situ TM7‒host associations. Using this method, we obtained a novel Saccharibacteria isolate TM7i and its host Leucobacter aridicollis J1 from Cicadae Periostracum, the castoff shell of cicada. Genomic analyses and microscopic characterizations revealed that TM7i could bind to J1 through twitching-like motility mediated by type IV pili (T4P). We further showed that the inhibition of T4P extrusion suppressed the motility and host adherence of TM7i, resulting in its reduced growth. However, the inactivation of T4P had little effect on the growth of TM7i that had already adhered to J1, suggesting the essential role of T4P in host recognition by TM7i. By capturing CPR‒host association and elaborating the T4P-dependent episymbiotic association mechanism, our studies shed light on the distinct yet widespread lifestyle of CPR bacteria.

AlmA involved in the long-chain n-alkane degradation pathway in Acinetobacter baylyi ADP1 is a Baeyer-Villiger monooxygenase.

Many Acinetobacter species can grow on n-alkanes of varying lengths (≤C40). AlmA, a unique flavoprotein in these Acinetobacter strains, is the only enzyme proven to be required for the degradation of long-chain (LC) n-alkanes, including C32 and C36 alkanes. Although it is commonly presumed to be a terminal hydroxylase, its role in n-alkane degradation remains elusive. In this study, we conducted physiological, biochemical, and bioinformatics analyses of AlmA to determine its role in n-alkane degradation by Acinetobacter baylyi ADP1. Consistent with previous reports, gene deletion analysis showed that almA was vital for the degradation of LC n-alkanes (C26-C36). Additionally, enzymatic analysis revealed that AlmA catalyzed the conversion of aliphatic 2-ketones (C10-C16) to their corresponding esters, but it did not conduct n-alkane hydroxylation under the same conditions, thus suggesting that AlmA in strain ADP1 possesses Baeyer-Villiger monooxygenase (BVMO) activity. These results were further confirmed by bioinformatics analysis, which revealed that AlmA was closer to functionally identified BVMOs than to hydroxylases. Altogether, the results of our study suggest that LC n-alkane degradation by strain ADP1 possibly follows a novel subterminal oxidation pathway that is distinct from the terminal oxidation pathway followed for short-chain n-alkane degradation. Furthermore, our findings suggest that AlmA catalyzes the third reaction in the LC n-alkane degradation pathway.IMPORTANCEMany microbial studies on n-alkane degradation are focused on the genes involved in short-chain n-alkane (≤C16) degradation; however, reports on the genes involved in long-chain (LC) n-alkane (>C20) degradation are limited. Thus far, only AlmA has been reported to be involved in LC n-alkane degradation by Acinetobacter spp.; however, its role in the n-alkane degradation pathway remains elusive. In this study, we conducted a detailed characterization of AlmA in A. baylyi ADP1 and found that AlmA exhibits Baeyer-Villiger monooxygenase activity, thus indicating the presence of a novel LC n-alkane biodegradation mechanism in strain ADP1.

Cartilage-Inspired, High-Strength, and Heat-Tolerant Lubricating Hydrogels by Macrophase Separation.

Hydrogels are considered as a potential cartilage replacement material based on their structure being similar to natural cartilage, which are of great significance in repairing cartilage defects. However, it is difficult for the existing hydrogels to combine the high load bearing and low friction properties (37 °C) of cartilage through sample methods. Herein, we report a facile and new fabrication strategy to construct the PNIPAm/EYL hydrogel by using the macrophase separation of supersaturated N-isopropylacrylamide (NIPAm) monomer solution to promote the formation of liposomes from egg yolk lecithin (EYL) and asymmetric template method. The PNIPAm/EYL hydrogels possess a relatively high compressive strength (more than 12 MPa), fracture energy (9820 J/m2), good fatigue resistance, lubricating properties, and excellent biocompatibility. Compared with the PNIPAm hydrogel, the friction coefficient (COF 0.046) of PNIPAm/EYL hydrogel is reduced by 50%. More importantly, the COF (0.056) of PNIPAm/EYL hydrogel above lower critical solution temperature (LCST) does not increase significantly, exhibiting heat-tolerant lubricity. The finite element analysis further proves that PNIPAm/EYL hydrogel can effectively disperse the applied stress and dissipate energy under load conditions. This work not only provides new insights for the design of high-strength lubricating hydrogels but also lays a foundation for the treatment of cartilage injury as a substitute material.

Sprayable Zwitterionic Antibacterial Hydrogel With High Mechanical Resilience and Robust Adhesion for Joint Wound Treatment.

Wound healing in movable parts, including the joints and neck, remains a critical challenge due to frequent motions and poor flexibility of dressings, which may lead to mismatching of mechanical properties and poor fitting between dressings and wounds; thus, increasing the risk of bacterial infection. This study proposes a sprayable zwitterionic antibacterial hydrogel with outstanding flexibility and desirable adhesion. This hydrogel precursor is fabricated by combining zwitterionic sulfobetaine methacrylate (SBMA) with poly(sulfobetaine methacrylate-co-dopamine methacrylamide)-modified silver nanoparticles (PSBDA@AgNPs) through robust electrostatic interactions. About 150 s of exposure to UV light, the SBMA monomer polymerizes to form PSB chains entangled with PSBDA@AgNPs, transformed into a stable and adhesion PSB-PSB@Ag hydrogel at the wound site. The resulting hydrogel has adhesive strength (15-38 kPa), large tensile strain (>400%), suitable shape adaptation, and excellent mechanical resilience. Moreover, the hydrogel displays pH-responsive behavior; the acidic microenvironment at the infected wound sites prompts the hydrogel to rapidly release AgNPs and kill bacteria. Further, the healing effect of the hydrogel is demonstrated on the rat neck skin wound, showing improved wound closing rate due to reduced inflammation and enhanced angiogenesis. Overall, the sprayable zwitterionic antibacterial hydrogel has significant potential to promote joint skin wound healing.

Drug-Embedded Nanovesicles Assembled from Peptide-Decorated Hyaluronic Acid for Rheumatoid Arthritis Synergistic Therapy.

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease that causes endless pain and poor quality of life in patients. Usage of a lubricant combined with anti-inflammatory therapy is considered a reasonable and effective approach for the treatment of RA. Herein, inspired by glycopeptides, a peptide-decorated hyaluronic acid was synthesized, and the grafted Fmoc-phenylalanine-phenylalanine-COOH (FmocFF) peptide self-assembled with ß-sheet conformations could induce the folding of polymer molecular chains to form a vesicle structure in aqueous solution. The hydrophobic anti-inflammatory drug curcumin (Cur) could be embedded in the vesicle walls through π-π interactions with the FmocFF peptide. Furthermore, the inflammation suppression function of the Cur-loaded vesicles both in vitro and in vivo was demonstrated to be an effective treatment for RA therapy. This work proposes new insights into the folding and hierarchical assembly of glycopeptide mimics, providing an efficient approach for constructing intelligent platforms for drug delivery, disease therapy, and diagnostic applications.

Dietary supplementation with Acremonium terricola culture alters the gut microbial structure and improves the growth performance, antioxidant status, and immune function of weaning piglets.

BACKGROUND: Acremonium terricola is used in the feed of dairy animals to promote growth and control diseases. However, the effects of dietary supplementation with A. terricola on the gut microbial structure of weaning piglets remain poorly understood. Therefore, in this study, we investigated the effects of dietary supplementation with A. terricola culture (ATC) on the growth performance, antioxidant status, immunity, and gut environment of weaning piglets. Sixty piglets were fed a basal diet supplemented with 1 g ATC/kg of basal diet (experimental group). Another 60 piglets did not receive ATC (control group). The intervention lasted for 20 days. RESULTS: The experimental group had higher daily weight gain and feed efficiency than did the control group. Significant increases were noted in the levels of serum insulin (P = 0.0018), insulin-like growth factor (P = 0.0018), triiodothyronine (P = 0.0031), immunoglobulin A (P < 0.0001), immunoglobulin M (P = 0.001), immunoglobulin G (P = 0.0001), and interferon γ (P < 0.0001) in the experimental group compared with the levels in the control group. Furthermore, ATC supplementation significantly reduced (P < 0.05) the relative abundance of Shuttleworthia, Succinivibrio, Roseburia, Ruminococcus, and Paludibacter but increased that of Phascolarctobacterium, Megasphaera, Faecalibacterium, and Prevotella in the experimental group compared with that in the control group. Notably, ATC supplementation significantly increased the relative abundance of Faecalibacterium prausnitzii (P < 0.05), which is involved in anti-inflammatory activities, gut barrier enhancement, and butyrate production. CONCLUSIONS: Dietary supplementation with ATC may improve the growth performance, antioxidant status, immunity, and fecal microflora of weaning pigs.

Mucosal bleeding correlates with submucosal microbial dysbiosis in peri-implant mucositis of patients with periodontitis.

OBJECTIVES: This study aimed to investigate the relationship between microbial communities and the severity of peri-implant mucosal bleeding in peri-implant mucositis. MATERIALS AND METHODS: Submucosal plaque samples were collected from 54 implants divided into the healthy implant (HI) group, peri-implant mucositis (PM) group, and peri-implantitis (PI) group. Sequencing of 16S rRNA was performed using the Illumina MiSeq platform. Alpha diversity (i.e., Shannon and Chao index) and beta diversity were used to measure microbial diversity within and between microbial communities, respectively. Differences in microbial taxa between groups were assessed via linear discriminate analysis effect size. Correlation between the modified sulcus bleeding index (mSBI) and microbial dysbiosis index (MDI) was examined using Spearman correlation analysis and linear models. RESULTS: The submucosal bacterial richness (Chao index) was positively correlated with the mean mSBI in the PM group. As the mean mSBI increased in the PM group, the beta diversity became closer to that of the PI group. In the PM group, the abundances of 47 genera were significantly correlated with the mean mSBI, and the MDI was positively associated with the mean mSBI. Fourteen of the forty-seven genera were discriminative taxa between the HI and PI groups, and the abundances of these biomarkers became closer to those in the PI group in the progression of peri-implant disease. CONCLUSIONS: A higher mSBI value corresponded to a higher risk of microbial dysbiosis in peri-implant mucositis. The biomarkers identified may be useful for monitoring the progression of peri-implant disease.

Response of Microbial Communities on Cathode with Different Potentials in a Single-Chamber Reactor.

Microbes use both organic and inorganic compounds as electron donors, with different electronic potentials, to produce energy required for growth in environments. Conventional studies on the effects of different electron donors on microbial community has been extensively studied with a set cathode potential. However, it remains under-researched how a microbial community response to the different redox potentials in different environments. Here, we incubated a lake sediment in a single-chamber reactor equipped with three working electrodes, i.e., with potentials of - 0.29 V, - 0.05 V versus standard hydrogen electrode and open-circuit, respectively. Results reveal that the structure of bacterial communities was highly similar for all closed-circuit electrodes (- 0.29 V, - 0.05 V), while differing significantly from those on open-circuit electrodes. We also show that specific bacteria were preferentially enriched by different electrode potentials, i.e., Pseudomonas and Rhodobacter preferentially grew on - 0.05 V and - 0.29 V cathode potentials, Azospirillum and Bosea preferentially grew on - 0.05 V; while Ferrovibrio, Hydrogenophaga, Delftia, and Sphingobium preferentially grew on - 0.29 V. In addition, microorganisms selectively enriched on open-circuit electrodes possess higher connectivity and closer relationship than microorganisms selectively enriched on closed-circuit electrode.

Structure of the Dietzia Mrp complex reveals molecular mechanism of this giant bacterial sodium proton pump.

Multiple resistance and pH adaptation (Mrp) complexes are sophisticated cation/proton exchangers found in a vast variety of alkaliphilic and/or halophilic microorganisms, and are critical for their survival in highly challenging environments. This family of antiporters is likely to represent the ancestor of cation pumps found in many redox-driven transporter complexes, including the complex I of the respiratory chain. Here, we present the three-dimensional structure of the Mrp complex from a Dietzia sp. strain solved at 3.0-Å resolution using the single-particle cryoelectron microscopy method. Our structure-based mutagenesis and functional analyses suggest that the substrate translocation pathways for the driving substance protons and the substrate sodium ions are separated in two modules and that symmetry-restrained conformational change underlies the functional cycle of the transporter. Our findings shed light on mechanisms of redox-driven primary active transporters, and explain how driving substances of different electric charges may drive similar transport processes.

Novel π/2-Periodic Planar Hall Effect Due to Orbital Magnetic Moments in MnBi2Te4.

The Berry curvature and orbital magnetic moment (OMM) come from either inversion symmetry or time-reversal symmetry breaking in quantum materials. Here, we demonstrate the significance of OMMs and Berry curvature in planar Hall effect (PHE) in antiferromagnetic topological insulator MnBi2Te4 flakes. We observe a PHE with period of π and positive magnitude at low fields, resembling the PHE of the surface states in nonmagnetic topological insulators. Remarkably, a novel predominant PHE with period of π/2 and negative magnitude emerges below the Néel temperature with B > 10 T. Our theoretical calculations reveal that this unusual π/2-periodic PHE originates from the topological OMMs of bulk Dirac electrons. Moreover, the competition between the contributions from the bulk and the surface states leads to nontrivial evolutions of PHE and anisotropic magnetoresistance. Our results reveal intriguing electromagnetic response due to the OMMs and also provide insight into the potential applications of magnetic topological insulators in spintronics.

Differential Interventional Effects of Omega-6 and Omega-3 Polyunsaturated Fatty Acids on High Fat Diet-Induced Obesity and Hepatic Pathology.

Current Dietary Guidelines for Americans recommend replacing saturated fat (SFA) intake with polyunsaturated fatty acids (PUFAs) and monosaturated fatty acids (MUFAs) but do not specify the type of PUFAs, which consist of two functionally distinct classes: omega-6 (n-6) and omega-3 (n-3) PUFAs. Given that modern Western diets are already rich in n-6 PUFAs and the risk of chronic disease remains high today, we hypothesized that increased intake of n-3 PUFAs, rather than n-6 PUFAs, would be a beneficial intervention against obesity and related liver diseases caused by high-fat diets. To test this hypothesis, we fed C57BL/6J mice with a high-fat diet (HF) for 10 weeks to induce obesity, then divided the obese mice into three groups and continued feeding for another 10 weeks with one of the following three diets: HF, HF+n-6 (substituted half of SFA with n-6 PUFAs), and HF+n-3 (substituted half of SFA with n-3 PUFAs), followed by assessment of body weight, fat mass, insulin sensitivity, hepatic pathology, and lipogenesis. Interestingly, we found that the HF+n-6 group, like the HF group, had a continuous increase in body weight and fat mass, while the HF+n-3 group had a significant decrease in body weight and fat mass, although all groups had the same calorie intake. Accordingly, insulin resistance and fatty liver pathology (steatosis and fat levels) were evident in the HF+n-6 and HF groups but barely seen in the HF+n-3 group. Furthermore, the expression of lipogenesis-related genes in the liver was upregulated in the HF+n-6 group but downregulated in the HF+n-3 group. Our findings demonstrate that n-6 PUFAs and n-3 PUFAs have differential effects on obesity and fatty liver disease and highlight the importance of increasing n-3 PUFAs and reducing n-6 PUFAs (balancing the n-6/n-3 ratio) in clinical interventions and dietary guidelines for the management of obesity and related diseases.

Efficient Treatment of Oily Sludge via Fast Microwave-Assisted Pyrolysis, Followed by Thermal Plasma Vitrification.

Oily sludge, as a critical hazardous waste, requires appropriate treatment for resource recovery and harmfulness reduction. Here, fast microwave-assisted pyrolysis (MAP) of oily sludge was conducted for oil removal and fuel production. The results indicated the priority of the fast MAP compared with the MAP under premixing mode, with the oil content in solid residues after pyrolysis reaching below 0.2%. The effects of pyrolysis temperature and time on product distribution and compositions were examined. In addition, pyrolysis kinetics can be well described using the Kissinger-Akahira-Sunose (KAS) and the Flynn-Wall-Ozawa (FWO) methods, with the activation energy being 169.7-319.1 kJ/mol in the feedstock conversional fraction range of 0.2-0.7. Subsequently, the pyrolysis residues were further treated by thermal plasma vitrification to immobilize the existing heavy metals. The amorphous phase and the glassy matrix were formed in the molten slags, resulting in bonding and, hence, immobilization of heavy metals. Operating parameters, including working current and melting time, were optimized to reduce the leaching concentrations of heavy metals, as well as to decrease their volatilization during vitrification.

Chinese Consensus Report on Family-Based Helicobacter pylori Infection Control and Management (2021 Edition).

OBJECTIVE: Helicobacter pylori infection is mostly a family-based infectious disease. To facilitate its prevention and management, a national consensus meeting was held to review current evidence and propose strategies for population-wide and family-based H. pylori infection control and management to reduce the related disease burden. METHODS: Fifty-seven experts from 41 major universities and institutions in 20 provinces/regions of mainland China were invited to review evidence and modify statements using Delphi process and grading of recommendations assessment, development and evaluation system. The consensus level was defined as ≥80% for agreement on the proposed statements. RESULTS: Experts discussed and modified the original 23 statements on family-based H. pylori infection transmission, control and management, and reached consensus on 16 statements. The final report consists of three parts: (1) H. pylori infection and transmission among family members, (2) prevention and management of H. pylori infection in children and elderly people within households, and (3) strategies for prevention and management of H. pylori infection for family members. In addition to the 'test-and-treat' and 'screen-and-treat' strategies, this consensus also introduced a novel third 'family-based H. pylori infection control and management' strategy to prevent its intrafamilial transmission and development of related diseases. CONCLUSION: H. pylori is transmissible from person to person, and among family members. A family-based H. pylori prevention and eradication strategy would be a suitable approach to prevent its intra-familial transmission and related diseases. The notion and practice would be beneficial not only for Chinese residents but also valuable as a reference for other highly infected areas.

Comparative transcriptome analysis reveals different adaptation mechanisms for degradation of very long-chain and normal long-chain alkanes in Dietzia sp. DQ12-45-1b.

Hydrocarbon-degrading bacteria typically metabolize a broad range of alkane substrates, but global metabolic characteristics of strains growing on alkane substrates in different chain lengths remain unclear. In this study, we analysed the transcriptional profiles of a hydrocarbon degrading bacterium, Dietzia sp. DQ12-45-1b, during growth on octacosane (C28), hexadecane (C16) and glucose as the sole carbon sources. Our results highlight that C16 and C28 induced common genes of core alkane degradation pathways in DQ12-45-1b, whereas transcriptional patterns of genes related to lipid metabolism, energy metabolism, biomass synthesis, and metal ion transportation were distinct. In addition, the transcriptional differences of genes related to glyoxylate shunt (GS) as well as growth phenotypes of mutant strain with defects in GS demonstrated that GS is essential for C16 degradation, though it is dispensable for C28 degradation in DQ12-45-1b. These results demonstrate that DQ12-45-1b cells exhibited considerable metabolic flexibility by using various mechanisms during growth on alkane substrates in different chain lengths. This study advances our knowledge of microbial hydrocarbon degradation and provides valuable information for the application of alkane-degrading bacteria in bioremediation and microbial enhanced oil recovery.

The Roles of the Two-Component System, MtrAB, in Response to Diverse Cell Envelope Stresses in Dietzia sp. DQ12-45-1b.

Two-component systems (TCSs) act as common regulatory systems allowing bacteria to detect and respond to multiple environmental stimuli, including cell envelope stress. The MtrAB TCS of Actinobacteria is critical for cell wall homeostasis, cell proliferation, osmoprotection, and antibiotic resistance, and thus is found to be highly conserved across this phylum. However, how precisely the MtrAB TCS regulates cellular homeostasis in response to environmental stress remains unclear. Here, we show that the MtrAB TCS plays an important role in the tolerance to different types of cell envelope stresses, including environmental stresses (i.e., oxidative stress, lysozyme, SDS, osmotic pressure, and alkaline pH stresses) and envelope-targeting antibiotics (i.e., isoniazid, ethambutol, glycopeptide, and ß-lactam antibiotics) in Dietzia sp. DQ12-45-1b. An mtrAB mutant strain exhibited slower growth compared to the wild-type strain and was characterized by abnormal cell shapes when exposed to various environmental stresses. Moreover, deletion of mtrAB resulted in decreased resistance to isoniazid, ethambutol, and ß-lactam antibiotics. Further, Cleavage under targets and tagmentation sequencing (CUT&Tag-seq) and electrophoretic mobility shift assays (EMSAs) revealed that MtrA binds the promoters of genes involved in peptidoglycan biosynthesis (ldtB, ldtA, murJ), hydrolysis (GJR88_03483, GJR88_4713), and cell division (ftsE). Together, our findings demonstrated that the MtrAB TCS is essential for the survival of Dietzia sp. DQ12-45-1b under various cell envelope stresses, primarily by controlling multiple downstream cellular pathways. Our work suggests that TCSs act as global sensors and regulators in maintaining cellular homeostasis, such as during episodes of various environmental stresses. The present study should shed light on the understanding of mechanisms for bacterial adaptivity to extreme environments. IMPORTANCE The multilayered cell envelope is the first line of bacterial defense against various extreme environments. Bacteria utilize a large number of sensing and regulatory systems to maintain cell envelope homeostasis under multiple stress conditions. The two-component system (TCS) is the main sensing and responding apparatus for environmental adaptation. The MtrAB TCS highly conserved in Actinobacteria is critical for cell wall homeostasis, cell proliferation, osmoprotection, and antibiotic resistance. However, how MtrAB works with regard to signals impacting changes to the cell envelope is not fully understood. Here, we found that in the Actinobacterium Dietzia sp. DQ12-45-1b, a TCS named MtrAB is pivotal for ensuring normal cell growth as well as maintaining proper cell morphology in response to various cell envelope stresses, namely, by regulating the expression of cell envelope-related genes. Our findings should greatly advance our understanding of the adaptive mechanisms responsible for maintaining cell integrity in times of sustained environmental shocks.

The Importance of a Genome-Wide Association Analysis in the Study of Alternative Splicing Mutations in Plants with a Special Focus on Maize.

Alternative splicing is an important mechanism for regulating gene expressions at the post-transcriptional level. In eukaryotes, the genes are transcribed in the nucleus to produce pre-mRNAs and alternative splicing can splice a pre-mRNA to eventually form multiple different mature mRNAs, greatly increasing the number of genes and protein diversity. Alternative splicing is involved in the regulation of various plant life activities, especially the response of plants to abiotic stresses and is also an important process of plant growth and development. This review aims to clarify the usefulness of a genome-wide association analysis in the study of alternatively spliced variants by summarizing the application of alternative splicing, genome-wide association analyses and genome-wide association analyses in alternative splicing, as well as summarizing the related research progress.

Omega-3 Polyunsaturated Fatty Acids Protect against High-Fat Diet-Induced Morphological and Functional Impairments of Brown Fat in Transgenic Fat-1 Mice.

The role of omega-3 polyunsaturated fatty acids (n-3 PUFAs) in the regulation of energy homeostasis remains poorly understood. In this study, we used a transgenic fat-1 mouse model, which can produce n-3 PUFAs endogenously, to investigate how n-3 PUFAs regulate the morphology and function of brown adipose tissue (BAT). We found that high-fat diet (HFD) induced a remarkable morphological change in BAT, characterized by "whitening" due to large lipid droplet accumulation within BAT cells, associated with obesity in wild-type (WT) mice, whereas the changes in body fat mass and BAT morphology were significantly alleviated in fat-1 mice. The expression of thermogenic markers and lypolytic enzymes was significantly higher in fat-1 mice than that in WT mice fed with HFD. In addition, fat-1 mice had significantly lower levels of inflammatory markers in BAT and lipopolysaccharide (LPS) in plasma compared with WT mice. Furthermore, fat-1 mice were resistant to LPS-induced suppression of UCP1 and PGC-1 expression and lipid deposits in BAT. Our data has demonstrated that high-fat diet-induced obesity is associated with impairments of BAT morphology (whitening) and function, which can be ameliorated by elevated tissue status of n-3 PUFAs, possibly through suppressing the effects of LPS on inflammation and thermogenesis.

[Imaging and Clinical Characteristics of Primary Pulmonary Mucoepidermoid Carcinoma].

Objective To improve the understanding and diagnostic accuracy of pulmonary mucoepidermoid carcinoma(PMEC) by analyzing the imaging and clinical characteristics.Methods The clinical and CT data of 27 cases of PMEC confirmed by histopathology in the First Medical Center of Chinese PLA General Hospital from January 2016 to December 2020 were retrospectively analyzed,including the location,size,margin,density,enhancement characteristics,accompanying signs,and pathological grade.Results The 27 cases included 6(6/27,22.2%) of large airway type,14(14/27,51.9%) of hilar type,and 7(7/27,26.9%) of peripheral type.The CT manifestations of 20 cases of large airway and hilar PMEC were soft-tissue nodules or mass with clear boundary in the lumen of the trachea and main bronchi,including 6 cases of mild enhancement,4 cases of moderate enhancement,5 cases of marked enhancement,and 5 cases of uneven enhancement.Three of the 20 cases showed calcification.The 7 cases of peripheral PMEC showed soft-tissue nodules or masses in the lungs,including 3 cases of mild enhancement,1 case of moderate enhancement,and 3 cases of marked enhancement. Obstructive pneumonia or atelectasis and bronchiectasis with mucus plug formation occurred in 16(16/27,59.3%) cases,lymph node metastasis in 9(9/27,33.3%) cases,and multiple organ metastasis in 8(8/27,29.6%) cases.Age(t=-3.132,P=0.005),enlarged lymph node (χ2=9.281,P=0.003),and distant metastasis(χ2=7.816,P=0.008) were statistically significant in the low-grade group and high-grade group. Conclusion PMEC have some unique imaging features,and recognizing these signs is conducive to the differential diagnosis and the improvement of the diagnostic accuracy.

Membrane vesicles from a Dietzia bacterium containing multiple cargoes and their roles in iron delivery.

Membrane vesicles (MVs) released from bacteria act as extracellular vehicles carrying various functional cargoes between cells. MVs with different cargoes play multiple roles in stress adaptation, nutrient acquisition and microbial interactions. However, previous studies have primarily focused on MVs from Gram-negative bacteria, while the characteristics of cargoes in MVs from Gram-positive bacteria and their involvement in microbial interactions remain to be elucidated. Here, we used a Gram-positive strain, Dietzia sp. DQ12-45-1b from Corynebacteriales, to analyse the characteristics and functions of MVs. We identified the 'antioxidant' canthaxanthin is stored within MVs by LC-MS/MS. In addition, nearly the entire genomic content of strain DQ12-45-1b are evenly distributed in MVs, suggesting that MVs from DQ12-45-1b might involve in horizontal gene transfer. Finally, the mycobactin-type siderophores were detected in MVs. The iron-loaded MVs effectively mediate iron binding and delivery to homologous bacteria from the order Corynebacteriales, but not to more distantly related species from the orders Pseudomonadales, Bacillales and Enterobacterales. These results revealed that the iron-loaded MVs are shared between homologous species. Together, we report the Gram-positive bacterium Dietzia sp. DQ12-45-1b released MVs that contain canthaxanthin, DNA and siderophores and prove that MVs act as public goods between closely related species.

Pan-genomic analysis reveals that the evolution of Dietzia species depends on their living habitats.

The bacterial genus Dietzia is widely distributed in various environments. The genomes of 26 diverse strains of Dietzia, including almost all the type strains, were analysed in this study. This analysis revealed a lipid metabolism gene richness, which could explain the ability of Dietzia to live in oil related environments. The pan-genome consists of 83,976 genes assigned into 10,327 gene families, 792 of which are shared by all the genomes of Dietzia. Mathematical extrapolation of the data suggests that the Dietzia pan-genome is open. Both gene duplication and gene loss contributed to the open pan-genome, while horizontal gene transfer was limited. Dietzia strains primarily gained their diverse metabolic capacity through more ancient gene duplications. Phylogenetic analysis of Dietzia isolated from aquatic and terrestrial environments showed two distinct clades from the same ancestor. The genome sizes of Dietzia strains from aquatic environments were significantly larger than those from terrestrial environments, which was mainly due to the occurrence of more gene loss events during the evolutionary progress of the strains from terrestrial environments. The evolutionary history of Dietzia was tightly coupled to environmental conditions, and iron concentrations should be one of the key factors shaping the genomes of the Dietzia lineages.