DNMT3A promotes glioma growth and malignancy via TNF-α/NF-κB signaling pathway.

Background: DNMT3A is the main molecule responsible for DNA methylation in cells. DNMT3A affects the progression of inflammation, degenerative diseases, and malignant tumors, and exhibits significant aberrantly expression in tumor tissues. Methods: Transcriptome data and relevant clinical information were downloaded from The Cancer Genome Atlas (TCGA), Chinese Glioma Genome Atlas (CGGA), and Gene Expression Omnibus (GEO) datasets. Differential expression analysis and prognostic analysis were conducted based on above statistics. We constructed a clinical prognostic model and identified DNMT3A as an independent prognostic factor to accurately predict patient prognosis. Differential gene enrichment analysis revealed that DNMT3A affects the progression of glioma through multiple pathways, among which the tumor necrosis factor-α (TNF-α)/nuclear factor-kappa B (NF-κB) pathway shows a strong correlation. Immunological analysis also revealed a certain correlation between DNMT3A and tumor immunity. We demonstrated through gene editing that DNMT3A can affect the release of TNF-α in cells, thereby affecting the progression of glioma. Functional experiments have also demonstrated that DNMT3A plays a crucial role in tumors. Results: RNA-sequencing and survival analyses of lower-grade glioma (LGG) patients in TCGA, CGGA, and GEO cohorts showed that high DNMT3A expression correlated with poor prognosis of LGG patients. Univariate and multivariate Cox regression analyses showed that DNMT3A expression was an independent prognostic indicator in LGG. The prognosis prediction nomogram with age, World Health Organization (WHO) grading, and DNMT3A expression showed reliable performance in predicting the 1-, 3-, and 5-year overall survival (OS) of LGG patients. Functional enrichment analysis, gene set enrichment analysis (GSEA), and ESTIMATE algorithm analyses showed that DNMT3A expression was associated with the tumor infiltration of immune cells and predicted response to immunotherapy in two immunotherapy cohorts of pan-cancer patients. Furthermore, short hairpin RNA (shRNA)-mediated knockdown of DNMT3A in the LGG cell lines suppressed proliferation, migration, and invasion of LGG cells by downregulating the TNF-α/NF-κB signaling pathway. Conclusions: Our data showed that DNMT3A was a potential prognostic biomarker in glioma. DNMT3A promoted proliferation and malignancy of LGG cells through the TNF-α/NF-κB signaling pathway. DNMT3A is a promising therapeutic target for treating patients with LGG.

A20 Promoter rs5029924 Concomitant with rs2230926 and rs5029937 May Be a Prognostic Predictor for Joint Deformity or Refractory Rheumatoid Arthritis.

Background: There have been several studies regarding the susceptibility of A20 gene SNPs (rs2230926 and rs5029937) in rheumatoid arthritis (RA). However, little is known about the association between polymorphisms in the A20 promoter and RA. The aim of this study was to investigate the characteristics of A20 promoter polymorphisms and the association between these polymorphisms and clinical significance in Chinese RA patients. Methods: PCR and sequencing were used to identify A20 gene polymorphisms in peripheral blood mononuclear cells (PBMCs) from 123 RA cases and 31 healthy individuals. Results: Only one SNP (rs5029924) in the A20 gene promoter was identified in RA patients and healthy individuals. 6 patients who carried heterozygous rs5029924 (3918C>T) together with heterozygous rs5029937 (11,571 G>T) and rs2230926 (12,486 T>G, Phe127Cys) suffered from joints deformity or refractory RA. Conclusion: We reported the A20 promoter polymorphism rs5029924 in RA patients for the first time. rs5029924 concomitant with rs2230926 and rs5029937 may be a prognostic predictor for joint deformity or refractory RA.

Long non-coding RNA RAD51-AS1 promotes the tumorigenesis of ovarian cancer by elevating EIF5A2 expression.

PURPOSE: The present study aims to determine the molecular mechanism mediated by RAD51 antisense RNA 1 (RAD51-AS1) in ovarian cancer (OvCA). METHODS: The data associated with RAD51-AS1 in OvCA were obtained from the Cancer Genome Atlas (TCGA) and the Gene Expression Omnibus (GEO) database. Relative expression of RAD51-AS1 was detected. Determination of cell proliferation, metastasis, and invasion was performed by cell counting, colony formation, would-healing, and transwell invasion assays. Protein levels were detected by western blotting. The molecular mechanism mediated by RAD51-AS1 was predicted by bioinformatics analysis and verified by dual-luciferase reporter assays. Subcutaneous tumorigenesis models were used to confirm the function of RAD51-AS1 in vivo. RESULTS: Data from TCGA and GEO showed that RAD51-AS1 was associated with poor prognosis in OvCA patients and DNA repair, cell cycle, focal adhesion, and apoptosis in SKOV3.ip cells. High levels of RAD51-AS1 were detected in OvCA cells. Overexpressing RAD51-AS1 enhanced the proliferative, invading, and migratory capabilities of OvCA cells in vitro while silencing RAD51-AS1 exhibited the opposite effects. Mechanically, RAD51-AS1 elevated eukaryotic initiation factor 5A2 (EIF5A2) expression as a sponge for microRNA (miR)-140-3p. Finally, the role of RAD51-AS1 was verified by subcutaneous tumorigenesis models. CONCLUSION: RAD51-AS1 promoted OvCA progression by the regulation of the miR-140-3p/EIF5A2 axis, which illustrated the potential therapeutic target for OvCA.

Clostridium butyricum isolated from giant panda can attenuate dextran sodium sulfate-induced colitis in mice.

Objective: Probiotics are beneficial to the intestinal barrier, but few studies have investigated probiotics from giant pandas. This study aims to explore the preventive effects of giant panda-derived Clostridium butyricum on dextran sodium sulfate (DSS)-induced colitis in mice. Methods: Clostridium butyricum was administered to mice 14 days before administering DSS treatment to induce enteritis. Results: Clostridium butyricum B14 could more effectively prevent colitis in mice than C. butyricum B13. C. butyricum B14 protected the mouse colon by decreasing the histology index and serum interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) levels, which improved intestinal inflammation-related symptoms. In addition, the treatment led to the regulation of the expression of Tifa, Igkv12-89, and Nr1d1, which in turn inhibited immune pathways. The expression of Muc4, Lama3, Cldn4, Cldn3, Ocln, Zo1, Zo2, and Snai is related the intestinal mucosal barrier. 16S sequencing shows that the C. butyricum B14 significantly increased the abundance of certain intestinal probiotics. Overall, C. butyricum B14 exerted a preventive effect on colitis in mice by inhibiting immune responses, enhancing the intestinal barrier and increasing the abundance of probiotic species. Thus, C. butyricum B14 administration helps regulate the balance of the intestinal microecology. It can suppress immune pathways and enhance barrier-protective proteins.

Courtship and mating behavior of Endoclita signifer (Hepialidae: Lepidoptera) and the male sex pheromones in hairbrushes.

Endoclita signifer Walker is the most destructive wood-boring pest of Eucalyptus in China, causing significant economic and ecological damage. As an insect of the primitive Lepidoptera family Hepialidae, E. signifer fly and mat for only 10-20 min at dusk. The courtship and mating behavior of E. signifer adults and whether male moths release sex pheromones are still unknown, especially since transitory flight survival strategies in primitive moths differ from advanced moths like noctuids. In this study, we first observed the courtship and mating behavior of E. signifer by considering the effects of space and then analyzed extracts of male hairbrushes using gas chromatography-electroantennogram detection. Our results indicated that during the courtship period, flying males form courtship fields, lekking, and chase flying females before mating with them; E. signifer were more successful in mating in larger spaces (Length × Width × Height = 9.6 × 7 × 4 m); 5 compounds in the hairbrushes of the male moths which elicited antennal responses of 2 sexes, despite at high concentrations. Combined with it, indicating that communication between male and female may rely on male sex pheromones. These findings can serve as a basis for studying the mechanisms of sex communication in E. signifer and developing sex pheromone-based trapping techniques.

Discovery of novel tetrahydrobenzothiophene derivatives as MSBA inhibitors for antimicrobial agents.

The incidence of infections caused by drug-resistant bacteria has been one of the most serious health threats in the past and is substantially increasing in an alarming rate. Therefore, the development of new antimicrobial agents to combat bacterial resistance effectively is urgent. This study focused on the design and synthesis of 40 novel tetrahydrobenzothiophene amide/sulfonamide derivatives and their antibacterial activities were evaluated. Compounds 2p, 6p, and 6 s exhibited significant inhibitory effects on the growth of bacteria. To assess their safety, the cytotoxicity of the compounds was assessed using human normal liver cells, revealing that compound 6p has lower cytotoxicity. A mouse wound healing experiment demonstrated that compound 6p effectively improved wound infection induced by trauma and accelerated the healing process. Compound 6p holds promise as a potential therapeutic agent for combating bacterial infections.

Constructing an eco-friendly and ratiometric fluorescent sensor for highly efficient detection of mercury ion in environmental samples.

Mercury ion (Hg2+) is a highly toxic and ubiquitous pollutant, whose effective detection has aroused widespread concern. A novel ratiometric fluorescent sensor has been designed to rapidly and efficiently detect Hg2+ based on blue/red carbon dots (CDs) with environmental friendliness. This sensor was well characterized via TEM, FTIR, XPS, UV-vis, and zeta potential analysis and displayed excellent fluorescence properties and stability. The fluorescence of blue CDs at 447 nm was significantly quenched with the addition of Hg2+ resulted from the static quenching, whereas that of red CDs at 650 nm remained invariable. A sensitive method for Hg2+ determination was constructed in the range of 0.05-7.0 nmol mL-1 with optimal conditions, and the detection limit was down to 0.028 nmol mL-1. Meanwhile, compared to other 17 metal ions, the ratiometric fluorescent sensor exhibited high selectivity for Hg2+. Furthermore, satisfied recoveries had also been obtained for measuring trace Hg2+ in practical environmental samples. This developed ratiometric fluorescent sensor provided a reliable, environmental-friendly, rapid, and efficient platform for the detection of Hg2+ in environmental applications.

The Correlation between the Gut Microbiota of Endoclita signifer (Lepidoptera, Hepialidae) Larvae and Their Host Preferences.

Insects' gut microbiota plays a crucial role in their host selection, adaptation, and plasticity. This study explored the impact of gut bacteria on the adaptation of host selection under different stresses (diverse feeding preferences and no feeding preferences). The seventh instar E. signifer larvae were artificially transferred from the most-selected host E. grandis × E. urophylla (Es) to more preferred hosts, M. apelta (Ma), as well as the non-preferred host, B. papyrifera (Bp). We then obtained the larval gut of three different feeding preference hosts. The gut bacterial DNA was sequenced and analyzed based on 16S rRNA. There were significant differences in the composition of dominant gut bacteria between Es with Ma and Bp, but without significant differences between Ma and Bp. In the process, Burkholderia and Microbacillus with degrading pesticides had significant changes, and Enterococcus with insect gut probiotics also had significant changes. The presence of enterococcus may be one of the main causes of intestinal microbiota changes before and after host transfer. Notably, when the feeding of E. signifer changes, the complex connections that exist between gut bacteria also change. Additionally, there was a negative correlation between the feeding preferences of E. signifer and the metabolic functions of their gut bacteria. This study provided a theoretical basis for the prediction and use of gut bacteria to interfere with the feeding of E. signifer.

The cross-level influence of ethical leadership on employee's OCBE: a two-wave study based on the social identity approach.

The importance of organizational citizenship behavior for the environment (OCBE) has received increasing attention in recent years because organizations face increasing pressure from environmental deterioration. The purpose of this study is to use social identity theory to construct a cross-level theoretical model of ethical leadership on OCBE, and to explore the cross-level influential mechanisms of ethical leadership on OCBE. Data collection was conducted via a two-wave distribution of leader-employee paired questionnaires in 20 manufacturing companies in China. In the first wave, data about OCBE and team environmental atmosphere were collected from leaders. Subsequently, 2 months later, we conducted the second wave of data collection when data about ethical leadership and leader identity were obtained from their employees. The results showed that at the individual level, ethical leadership has a significant positive impact on employees' OCBE, and such relationship is partially mediated by employees' leader identity and positively moderated by team environmental atmosphere across levels. At the team level, ethical leadership has a significant positive impact on employees' OCBE, and such relationship is completely mediated by team environmental atmosphere. This study investigates the cross-level influential mechanism of ethical leadership on OCBE in China and provides theoretical guidance for enterprises to promote OCBE effectively.

Sustainable luxury purchase behavior in the Post-Pandemic Era: a grounded theory study in China.

Despite the increasing sustainable practices from the luxury industry, research show little evidence on consumers' reactions toward sustainable luxury. This paper aims at understanding changes in consumers' consumption behavior toward sustainable luxury fashion products in the Post-Pandemic Era. We use exploratory qualitative research conducted by semi-structured in-depth interviews involving luxury consumers in China based on grounded theory. With the help of Nvivo12, the interview data is coded and analyzed to identify the influencing attitude and intention of sustainable luxury fashion in China in the Post-Pandemic Era. The findings show that hedonic value, uniqueness value, social value, functional value (practicality, quality, and value for money), health value and sustainable value affect purchase intention toward sustainable luxury in the Post-Pandemic Era. A theoretical model is built to systematically analyze the determinants of purchase behavior. This study will contribute to the literature on sustainable luxury fashion behaviors by performing in-depth interviews in the Post-Pandemic Era. Besides, the findings provide guidance for industries to make customer-based sustainable strategies when practicing sustainable development in luxury fashion in China.

Time-Dependent Factors Influencing Cardiocerebral Vascular Events in Chronic Hemodialysis Patients: Insights from a Longitudinal Study.

BACKGROUND Cardiocerebral vascular events (CVCs) are significant complications in patients undergoing hemodialysis (HD). Given the increased morbidity and mortality associated with CVCs in this population, understanding the factors influencing CVC occurrence over time is crucial. This study aimed to investigate these time-dependent factors in HD patients. MATERIAL AND METHODS A total of 228 HD patients from 2 dialysis centers, with at least 3 months of treatment between 2017 and 2021, were included. Annual clinical data were collected, and patients were monitored until CVC development. Kaplan-Meier analysis and a time-dependent Cox regression model were used for data analysis. RESULTS The mean age of 228 patients was 55.0±15.0 years, and 64.76% were male. For 5 years of monitoring, the mean follow-up interval was 3.1±1.0 years for patients to develop CVCs. The 1-year, 3-year, and 5-year CVC-free rates were 97.47%, 81.31%, and 70.71%, respectively. Time-dependent Cox regression revealed that C-reactive protein was an independent time-dependent risk factor in HD patients and blood flow rate was an independent time-dependent protective factor. The male subgroup and non-diabetic subgroup had these same results. The following were was the independent time-dependent risk factors: white blood cell count for the female subgroup; blood flow rate for the non-elderly subgroup; and C-reactive protein for the diabetic subgroup. None were risk factors for the elderly subgroup. CONCLUSIONS It took an average of 3.1±1.0 years for patients with HD to develop CVCs. C-reactive protein and blood flow rate emerged as key time-dependent influencing factors for CVCs in this population.

The Influence of Workplace Envy on Employees' Knowledge-Hiding Behavior Based on a Comparative Analysis between Generation Cohorts.

How to promote the free flow of knowledge among employees is the core factor used to improve the innovation ability and even competitive advantage of an organization. Research on how to reduce knowledge-hiding behavior and promote knowledge sharing among employees becomes the key to enhancing the technological innovation capability of enterprises and effectively responding to the VUCA environment at present. Based on social comparison theory and regulatory focus theory, this study uses 402 enterprise employees as samples to deeply study the influence mechanism of workplace envy on their knowledge-hiding behavior and compare the differences between new-generation employees and non-new-generation employees. The research results show that: (1) employee's benign envy has a significant negative effect on knowledge-hiding behavior, while malicious envy has a significant positive effect on knowledge-hiding behavior. (2) Promotion regulatory focus plays a partly mediating effect between benign envy and employee knowledge-hiding behavior, while prevention regulatory focus also plays a partly mediating effect between malicious envy and employee knowledge-hiding behavior. (3) Generation not only has a positive moderating effect on the relationship between benign envy and promotion regulatory focus but also has a positive moderating effect on the relationship between malicious envy and prevention regulatory focus. This study further found that the younger the employee generation cohort, the more substantial the effect of benign envy on the promotion regulatory focus, while the older the employee generation cohort, the more substantial the effect of malicious envy on the prevention regulatory focus.

First Isolation and Identification of Aeromonas veronii in a Captive Giant Panda (Ailuropoda melanoleuca).

The objective of this study was to understand biological characteristics of one bacteria strain named as VPG which was isolated from multiple organs of a dead captive giant panda cub. Here, we use biochemical tests, 16S rRNA and gyrB genes for bacterial identification, the disk diffusion method for antibiotic resistance phenotype, smart chip real-time PCR for the antibiotic resistance genotype, multiplex PCR for determination of virulence genes, and the acute toxicity test in mice for testing the pathogenicity of isolates. The isolate was identified as A. veronii strain based on the biochemical properties and genetic analysis. We found that the strain carried 31 antibiotic resistance genes, revealed antimicrobial resistance phenotypically to several antibiotics including penicillin, ampicillin, oxacillin, amoxicillin, imipenem, and vancomycin, and carried virulence genes including aer, act, lip, exu, ser, luxs, and tapA. The main pathological changes in giant panda were congestion, necrotic lesions and a large number of bacteria in multiple organs. In addition, the LD50 in Kunming mice infected with strain VGP was 5.14 × 107 CFU/mL by intraperitoneal injection. Infection with strain VGP led to considerable histological lesions such as hemorrhage of internal organs, necrosis of lymphocytes and neurons in Kunming mice. Taken together, these results suggest that infection with strain VGP would be an important causes of death in this giant panda cub.

Brain morphology and functional connectivity alterations in patients with severe obstructive sleep apnea.

BACKGROUND: It has been demonstrated that widespread structural and functional brain alterations influence the development of cognitive impairment in patients with obstructive sleep apnea (OSA). However, the literature has limited evidence regarding the neuropathophysiological mechanisms behind these impairments. This research aimed to investigate brain morphologic and functional connectivity (FC) abnormalities related to neurocognitive function in OSA. METHODS: Fifty treatment-naïve males, newly diagnosed patients with severe OSA, and 50 well-matched healthy controls (HCs) were enrolled prospectively. All subjects underwent an MRI scan, cognitive psychological and sleep scale assessment. The differences of brain morphological and seed-based FC between the two groups were compared. The correlation analysis and receiver operating characteristic curve were performed for further analysis. RESULTS: Compared with HCs, the right brainstem, left dorsal-lateral superior frontal gyrus (SFGdor), and superior temporal gyrus (STG) exhibited atrophy in the OSA group. In addition, FC between the left SFGdor and the right postcentral gyrus (PoCG) was increased, which was positively correlated with disease duration (r = 0.312, FDR-corrected P = 0.027). The Jacobian values of the brainstem were negatively correlated with MoCA and recall scores (r = -0.449, FDR-corrected P = 0.0025; r = -0.416, FDR-corrected P = 0.005). Furthermore, the Jacobian values of the left SFGdor demonstrated a relatively high diagnostic performance (sensitivity: 86%, specificity: 56%, AUC: 0.740, 95% CI: 0.643-0.836, P < 0.0001). CONCLUSIONS: Structural atrophy in brainstem and frontotemporal lobe and altered FC may be the neurobiological hallmark of brain impairment in OSA. Notably, brainstem atrophy has been associated with cognitive impairment, which may provide new insights into understanding the neuropathophysiological mechanisms of cognitive impairment in OSA patients.

Ferrostatin-1 post-treatment attenuates acute kidney injury in mice by inhibiting ferritin production and regulating iron uptake-related proteins.

Background: Acute kidney injury (AKI) is a common and serious medical condition with high morbidity and mortality. Recent research has highlighted ferroptosis, a novel form of programmed cell death, as a potential therapeutic target in mitigating renal tubular injury in AKI. Ferrostatin-1, a specific ferroptosis inhibitor, has been demonstrated to prevent renal injury through ferroptosis inhibition. Methods: Utilizing a murine AKI model, we investigated the effects of Ferrostatin-1 by administering it post-injury. Through high-throughput sequencing and pathological analysis, we focused on the critical role of ferroptosis-related pathways in the treatment. Results: Ferrostatin-1 post-conditioning effectively mitigated oxidative damage and reduced iron content associated with AKI. Additionally, critical ferroptosis-related proteins, such as GPX4, SLC7A11, NRF2, and FTH1, exhibited increased expression levels. In vitro, Ferrostatin-1 treatment of HK-2 cells significantly diminished lipid peroxidation and iron accumulation. Furthermore, Ferrostatin-1 was found to downregulate the PI3K signalling pathway. Conclusion: Ferrostatin-1 acted as a potential ferroptosis inhibitor with the capacity to enhance antioxidant defences. This study suggests that Ferrostatin-1 could serve as a promising novel strategy for improving the treatment of AKI and promoting recovery from the condition.

C5a-C5aR1 induces endoplasmic reticulum stress to accelerate vascular calcification via PERK-eIF2α-ATF4-CREB3L1 pathway.

AIMS: Vascular calcification (VC) predicts the morbidity and mortality in cardiovascular diseases. Vascular smooth muscle cells (VSMCs) osteogenic transdifferentiation is the crucial pathological basis for VC. To date, the molecular pathogenesis is still largely unclear. Notably, C5a-C5aR1 contributes to the development of cardiovascular diseases, and its closely related to physiological bone mineralization which is similar to VSMCs osteogenic transdifferentiation. However, the role and underlying mechanisms of C5a-C5aR1 in VC remain unexplored. METHODS AND RESULTS: A cross-sectional clinical study was utilized to examine the association between C5a and VC. Chronic kidney diseases mice and calcifying VSMCs models were established to investigate the effect of C5a-C5aR1 in VC, evaluated by changes in calcium deposition and osteogenic markers. The cross-sectional study identified that high level of C5a was associated with increased risk of VC. C5a dose-responsively accelerated VSMCs osteogenic transdifferentiation accompanying with increased the expression of C5aR1. Meanwhile, the antagonists of C5aR1, PMX 53, reduced calcium deposition, and osteogenic transdifferentiation both in vivo and in vitro. Mechanistically, C5a-C5aR1 induced endoplasmic reticulum (ER) stress and then activated PERK-eIF2α-ATF4 pathway to accelerated VSMCs osteogenic transdifferentiation. In addition, cAMP-response element-binding protein 3-like 1 (CREB3L1) was a key downstream mediator of PERK-eIF2α-ATF4 pathway which accelerated VSMCs osteogenic transdifferentiation by promoting the expression of COL1α1. CONCLUSIONS: High level of C5a was associated with increased risk of VC, and it accelerated VC by activating the receptor C5aR1. PERK-eIF2α-ATF4-CREB3L1 pathway of ER stress was activated by C5a-C5aR1, hence promoting VSMCs osteogenic transdifferentiation. Targeting C5 or C5aR1 may be an appealing therapeutic target for VC.

lncRNA GHET1 regulates extravillous trophoblastic phenotype via EZH2/LSD1-mediated MT2A epigenetic suppression in pre-eclampsia.

Pre-eclampsia (PE) is usually defined as new-onset hypertension with albuminuria or other organ damage. Herein, the role and mechanism of long noncoding RNA (lncRNA) gastric carcinoma high expressed transcript 1 (GHET1) during PE are investigated. Expression of GHET1 in PE pregnancies was evaluated using quantitative real-time polymerase chain reaction (qRT-PCR). Proliferation and cell cycle of extravillous trophoblasts were assessed by Cell Counting Kit-8 (CCK-8), colony formation, 5-Ethynyl-2'-deoxyuridine (EdU) assays, and flow cytometry, respectively. Migration, invasion, and network formation of trophoblasts were measured by wound healing, transwell system, and tube formation assays. RNA immunoprecipitation (RIP), RNA pull-down, and chromatin immunoprecipitation (ChIP) assays were used to confirm the molecular interaction. GHET1 was markedly decreased in the placenta of PE patients. GHET1 promoted the proliferation and cell cycle of extravillous trophoblasts, as well as migration, invasion, and network formation in vitro. Metallothionein 2A (MT2A) functioned as a downstream effector of GHET1, which was negatively correlated with GHET1 in PE. GHET1 directly bound with zeste 2 polycomb repressive complex 2/lysine-specific demethylase 1 (EZH2/LSD1). Knockdown of GHET1 reduced the occupancies of H3K27me3 and H3K4me2 in the MT2A promoter region by recruiting EZH2 and LSD1. MT2A knockdown reversed GHET1 inhibition mediated biological functions. GHET1 regulates extravillous trophoblastic phenotype via EZH2/LSD1-mediated MT2A epigenetic suppression in PE.

Copiotrophy in a Marine-Biofilm-Derived Roseobacteraceae Bacterium Can Be Supported by Amino Acid Metabolism and Thiosulfate Oxidation.

Copiotrophic bacteria that respond rapidly to nutrient availability, particularly high concentrations of carbon sources, play indispensable roles in marine carbon cycling. However, the molecular and metabolic mechanisms governing their response to carbon concentration gradients are not well understood. Here, we focused on a new member of the family Roseobacteraceae isolated from coastal marine biofilms and explored the growth strategy at different carbon concentrations. When cultured in a carbon-rich medium, the bacterium grew to significantly higher cell densities than Ruegeria pomeroyi DSS-3, although there was no difference when cultured in media with reduced carbon. Genomic analysis showed that the bacterium utilized various pathways involved in biofilm formation, amino acid metabolism, and energy production via the oxidation of inorganic sulfur compounds. Transcriptomic analysis indicated that 28.4% of genes were regulated by carbon concentration, with increased carbon concentration inducing the expression of key enzymes in the EMP, ED, PP, and TCA cycles, genes responsible for the transformation of amino acids into TCA intermediates, as well as the sox genes for thiosulfate oxidation. Metabolomics showed that amino acid metabolism was enhanced and preferred in the presence of a high carbon concentration. Mutation of the sox genes decreased cell proton motive force when grown with amino acids and thiosulfate. In conclusion, we propose that copiotrophy in this Roseobacteraceae bacterium can be supported by amino acid metabolism and thiosulfate oxidation.

Salinimicrobium profundisediminis sp. nov., isolated from deep-sea sediment of the Mariana Trench.

A Gram-stain-negative, aerobic, rod-shaped, non-gliding bacterial strain, designated as MT39T, was isolated from a deep-sea sediment sample collected from the Mariana Trench. Strain MT39T grew optimally at 35°C and pH 7.0, and could tolerate up to 10% (w/v) NaCl. The strain was positive for catalase and negative for oxidase. The genome of strain MT39T was 4 033 307 bp, with a 41.1 mol % genomic G+C content and 3514 coding sequences. Phylogenetic analysis based on 16S rRNA gene sequences placed strain MT39T within the genus Salinimicrobium, showing the highest 16S rRNA gene sequence similarity to Salinimicrobium terrea CGMCC 1.6308T (98.1%). The average nucleotide identity and in silico DNA-DNA hybridization values between strain MT39T and the type strains of seven Salinimicrobium species were all less than the threshold values to discriminate bacterial species, indicating that strain MT39T is affiliated with a novel species within the genus. The major cellular fatty acids of strain MT39T were iso-C15 : 0, anteiso-C15 : 0 and iso-C17 : 0 3-OH. Polar lipids of strain MT39T included phosphatidylethanolamine, one unidentified aminolipid and four unidentified lipids. Menaquinone-6 was the only respiratory quinone in strain MT39T. On the basis of the polyphasic data present in this study, strain MT39T represents a novel species of the genus Salinimicrobium, for which the name Salinimicrobium profundisediminis sp. nov. is proposed, with type strain being MT39T (=MCCC 1K07832T=KCTC 92381T).

Anaerobic thiosulfate oxidation by the Roseobacter group is prevalent in marine biofilms.

Thiosulfate oxidation by microbes has a major impact on global sulfur cycling. Here, we provide evidence that bacteria within various Roseobacter lineages are important for thiosulfate oxidation in marine biofilms. We isolate and sequence the genomes of 54 biofilm-associated Roseobacter strains, finding conserved sox gene clusters for thiosulfate oxidation and plasmids, pointing to a niche-specific lifestyle. Analysis of global ocean metagenomic data suggests that Roseobacter strains are abundant in biofilms and mats on various substrates, including stones, artificial surfaces, plant roots, and hydrothermal vent chimneys. Metatranscriptomic analysis indicates that the majority of active sox genes in biofilms belong to Roseobacter strains. Furthermore, we show that Roseobacter strains can grow and oxidize thiosulfate to sulfate under both aerobic and anaerobic conditions. Transcriptomic and membrane proteomic analyses of biofilms formed by a representative strain indicate that thiosulfate induces sox gene expression and alterations in cell membrane protein composition, and promotes biofilm formation and anaerobic respiration. We propose that bacteria of the Roseobacter group are major thiosulfate-oxidizers in marine biofilms, where anaerobic thiosulfate metabolism is preferred.