Dormancy and double-activation strategy for construction of high-performance mixed-matrix membranes.

Mixed-matrix membranes (MMMs) have the potential for energy-efficient gas separation by matching the superior mass transfer and anti-plasticization properties of the fillers with processability and scaling up features of the polymers. However, construction of high-performance MMMs has been prohibited due to low filler-loading and the existence of interfacial defects. Here, high MOF-loaded, i.e., 55 wt %, MMMs are developed by a 'dormancy and double-activation' (DDA) strategy. High MOF precursor concentration suppresses crystallization in the membrane casting solution, realizing molecular level mixing of all components. Then, the polymeric matrix was formed with uniform encapsulation of MOF nutrients. Subsequently, double-activation was employed to induce MOF crystallization: the alkali promotes MOFs nucleation to harvest small porous nanocrystals while excessive ligands activate the metal ions to enhance the MOFs conversion. As such, quasi-semi-continuous mass transfer channels can be formed in the MMMs by the connected MOFs nanocrystals to boost the gas permeability. The optimized MMM shows significantly ameliorated CO2 permeability, i.e., 2841 Barrer, five-fold enhancement compared with pristine polymer membrane, with a good CO2 /N2 selectivity of 36. Besides, the nanosized MOFs intensify their interaction with polymer chains, endowing the MMMs with good anti-plasticization behaviour and stability, which advances practical application of MMMs in carbon capture.

Rapid Fabrication of High-Permeability Mixed Matrix Membranes at Mild Condition for CO2 Capture.

Mixed matrix membranes (MMMs), conjugating the advantages of flexible processing-ability of polymers and high-speed mass transfer of porous fillers, are recognized as the next-generation high-performance CO2 capture membranes for solving the current global climate challenge. However, controlling the crystallization of porous metal-organic frameworks (MOFs) and thus the close stacking of MOF nanocrystals in the confined polymer matrix is still undoable, which thus cannot fully utilize the superior transport attribute of MOF channels. In this study, the "confined swelling coupled solvent-controlled crystallization" strategy is employed for well-tailoring the in-situ crystallization of MOF nanocrystals, realizing rapid (<5 min) construction of defect-free freeway channels for CO2 transportation in MMMs due to the close stacking of MOF nanocrystals. Consequently, the fabricated MMMs exhibit approximately fourfold enhancement in CO2 permeability, i.e., 2490 Barrer with a CO2 /N2 selectivity of 37, distinctive antiplasticization merit, as well as long-term running stability, which is at top-tier level, enabling the large-scale manufacture of high-performance MMMs for gas separation.

Temporal variation and sharing of antibiotic resistance genes between water and wild fish gut in a peri-urban river.

Antibiotic resistance genes (ARGs) as emergence contaminations have spread widely in the water environment. Wild fish may be recipients and communicators of ARGs in the water environment, however, the distribution and transmission of ARGs in the wild fish and relevant water environment were rarely reported. Here, we have profiled ARGs and bacterial communities in wild freshwater fish and relevant water in a peri-urban river using high-throughput qPCR and 16S rRNA gene sequence. A total of 80 and 220 unique ARG subtypes were identified in fish and water samples. Fish and water both showed significant ARG seasonal variations (P < 0.05). The highest absolute abundance of ARGs in fish and water occurred in summer (1.32 × 109 copies per g, on average) and autumn (9.04 × 106 copies per mL), respectively. In addition, the bipartite network analysis showed that 9 ARGs and 1 mobile genetic element continuously shared in fish and water. Furthermore, bacteria shared in fish and water were found to significantly correlate with shard ARGs. The findings demonstrate that bacteria and ARGs in fish and water could interconnect and ARGs might transfer between fish and water using bacteria as a spreading medium.

DNMT3a mediates paclitaxel-induced abnormal expression of LINE-1 by increasing the intragenic methylation.

The activation of long interspersed nuclear element-1 (LINE-1) leads to genomic instability, which promotes carcinogenesis and drug resistant. Therefore, exploring the mechanism underlying LINE-1 abnormal activation has the theoretical and clinical significance. DNA methylation is an important way to regulate gene expression. DNMT3a, one member of the DNA methyltransferase family, not only inhibits gene expression by inducing promoter hypermethylation, but also activates gene expression by increasing the intragenic DNA methylation. Our previous studies found that the expression of LINE-1 did not increase significantly in the promoter methylation in breast cancer cells treated with paclitaxel (PTX), a first-line chemotherapeutic drug for breast cancer. Here we explored whether DMNMT3a could directly mediate the drug-induced activation of LINE-1 in breast cancer cells through increasing the LINE-1 intragenic methylation. Our ChIP experiments and methyl analysis showed that treatment of breast cancer cells with PTX not only induced DNMT3a expression, but also promoted the binding of DNMT3a to the inner region of the LINE-1 gene to increase its methylation, resulting in upregulation of LINE-1 expression. Using expression vectors or RNA interference to alter the DNMT3a expression levels in the cells significantly changed the intragenic methylation degree and LINE-1 expression. Moreover, down-regulation of DNMT3a expression effectively inhibited the expression of LINE-1. These results indicate that DNMT3a-mediated intragenic methylation plays an important role in drug-induced abnormal activation of LINE-1, which provides a new idea for understanding the mechanism of abnormal activation of Line-1 induced by chemotherapy drug stress in breast cancer cells.

[The NOXA promoter could function as an active enhancer to regulate the expression of BCL2 in the apoptosis response].

The transcription of eukaryotic genes is regulated by both proximal promoters and distal enhancers. Some promoters also have enhancer activity. NOXA and BCL2 are pro-apoptotic and anti-apoptotic members of the BCL2 family of protein, respectively. Our previous study has found that the NOXA gene promoter and the BCL2 gene promoter interact at the level of three-dimensional chromatin structure. Moreover, the NOXA gene promoter region displays histone modifications characteristic of both promoters and enhancers. This study aimed to explore whether and when the NOXA promoter could act as an active enhancer to regulate BCL2 expression. Based on the apoptosis model of MCF-7 cells induced by camptothecin, we used chromosome conformation capture (3C), quantitative real-time PCR (qRT-PCR) and the luciferase reporter gene technology to demonstrate that the NOXA promoter could function as an active enhancer and physically interact with the BCL2 promoter through chromatin looping. The regulatory properties of the NOXA promoter were closely related to the strength of the apoptosis stimulation. Under weak apoptotic stimulation (1 µmol/L camptothecin treatment), the NOXA promoter mainly functioned as an enhancer; with the enhancement of apoptotic stimulation (10 µmol/L camptothecin treatment), the NOXA promoter activity increased and mainly regulated the expression of the gene itself to promote apoptosis. Chromatin immunoprecipitation (ChIP) confirmed that the dynamic changes of the promoter activity and enhancer activity in the NOXA promoter region are consistent with its histone modification marks. This study provides new clues for further exploring the mechanism underlying cooperative response of BCL2 family member to apoptosis stimuli.

Chemical Modification toward Long Spin Lifetimes in Organic Conjugated Radicals.

Organic semiconductors for spin-based devices require long spin relaxation times. Understanding their spin relaxation mechanisms is critical to organic spintronic devices and applications for quantum information processing. However, reports on the spin relaxation mechanisms of organic conjugated molecules are rare and the research methods are also limited. Herein, we study the molecular design and spin relaxation mechanisms by systematically varying the structure of a conjugated radical. We found that solid-state relaxation times of organic materials are largely different from that in solution state. We demonstrate that substitution of a lower gyromagnetic ratio nucleus (e. g. D, Cl) on the para-position of the aryl rings in the triphenylmethyl (TM) radical can significantly improve their coherence times (Tm ). Flexible thin films based on such radicals exhibit ultra-long spin-lattice relaxation times (T1 ) up to 35.6(6) µs and Tm up to 1.08(4) µs under ambient conditions, which are among the longest values in films. More importantly, using the TM radical derivative (5CM), we observed room-temperature quantum coherence and Rabi cycles in thin film for the first time, suggesting that organic conjugated radicals have great potentials for spin-based information processing.

Deciphering basic and key traits of antibiotic resistome in influent and effluent of hospital wastewater treatment systems.

Hospital wastewater treatment system (HWTS) is an important source and environmental reservoir of clinically relevant antibiotic resistance genes (ARGs). However, how antibiotic resistome of clinical wastewater changed in HWTS is poorly understood. Herein, the basic quantitative traits (i.e., diversity and abundance) of ARGs in three HWTSs were profiled by metagenomics. In total, 709 ARG subtypes belonging to 20 ARG types were detected with relative abundance ranging from 1.12 × 10-5 to 7.33 × 10-1 copies/cell. Notably, most ARGs could not be significantly removed by chlorination treatment in the HWTS. These ARGs were identified to confer resistance to almost all major classes of antibiotics and include ARGs of last-resort antibiotics, such as blaNDM, mcr and tet(X) which were abundantly occurred in HWTS with 19, 5 and 7 variants, respectively. Moreover, qualitative analysis based on metagenome-assembled genome (MAG) analysis revealed that the putative hosts of the identified ARGs were broadly distributed into at least 8 dominant bacterial phyla. Of the 107 ARG-carrying MAGs recovered, 39 encoded multi-antibiotic resistance and 16 belonged to antibiotic resistant pathogens. Further analysis of co-occurrence patterns of ARGs with mobile genetic elements suggested their potential mobility. These key qualitative traits of ARGs provided further information about their phylogeny and genetic context. This study sheds light on the key traits of ARGs associated with resistance dissemination and pathogenicity and health risks of clinical wastewater.

Construction and Identification of an NLR-Associated Prognostic Signature Revealing the Heterogeneous Immune Response in Skin Cutaneous Melanoma.

Background: Skin cutaneous melanoma (SKCM) is the deadliest dermatology tumor. Ongoing researches have confirmed that the NOD-like receptors (NLRs) family are crucial in driving carcinogenesis. However, the function of NLRs signaling pathway-related genes in SKCM remains unclear. Objective: To establish and identify an NLRs-related prognostic signature and to explore its predictive power for heterogeneous immune response in SKCM patients. Methods: Establishment of the predictive signature using the NLRs-related genes by least absolute shrinkage and selection operator-Cox regression analysis (LASSO-COX algorithm). Through univariate and multivariate COX analyses, NLRs signature's independent predictive effectiveness was proven. CIBERSORT examined the comparative infiltration ratios of 22 distinct types of immune cells. RT-qPCR and immunohistochemistry implemented expression validation for critical NLRs-related prognostic genes in clinical samples. Results: The prognostic signature, including 7 genes, was obtained by the LASSO-Cox algorithm. In TCGA and validation cohorts, SKCM patients with higher risk scores had remarkably poorer overall survival. The independent predictive role of this signature was confirmed by multivariate Cox analysis. Additionally, a graphic nomogram demonstrated that the risk score of the NLRs signature has high predictive accuracy. SKCM patients in the low-risk group revealed a distinct immune microenvironment characterized by the significantly activated inflammatory response, interferon-α/γ response, and complement pathways. Indeed, several anti-tumor immune cell types were significantly accumulated in the low-risk group, including M1 macrophage, CD8 T cell, and activated NK cell. It is worth noting that our NLRs prognostic signature could serve as one of the promising biomarkers for predicting response rates to immune checkpoint blockade (ICB) therapy. Furthermore, the results of expression validation (RT-qPCR and IHC) were consistent with the previous analysis. Conclusion: A promising NLRs signature with excellent predictive efficacy for SKCM was developed.

Identifying s-wave pairing symmetry in single-layer FeSe from topologically trivial edge states.

Determining the pairing symmetry of single-layer FeSe on SrTiO3 is the key to understanding the enhanced pairing mechanism. It also guides the search for superconductors with high transition temperatures. Despite considerable efforts, it remains controversial whether the symmetry is the sign-preserving s- or the sign-changing s±-wave. Here, we investigate the pairing symmetry of single-layer FeSe from a topological point of view. Using low-temperature scanning tunneling microscopy/spectroscopy, we systematically characterize the superconducting states at edges and corners of single-layer FeSe. The tunneling spectra collected at edges and corners show a full energy gap and a substantial dip, respectively, suggesting the absence of topologically non-trivial edge and corner modes. According to our theoretical calculations, these spectroscopic features can be considered as strong evidence for the sign-preserving s-wave pairing in single-layer FeSe.

Charge instability of topological Fermi arcs in chiral crystal CoSi.

Topological boundary states emerged at the spatial boundary between topological non-trivial and trivial phases, are usually gapless, or commonly referred as metallic states. For example, the surface state of a topological insulator is a gapless Dirac state. These metallic topological boundary states are typically well described by non-interacting fermions. However, the behavior of topological boundary states with significant electron-electron interactions, which could turn the gapless boundary states into gapped ordered states, e.g., density wave states or superconducting states, is of great interest theoretically, but is still lacking evidence experimentally. Here, we report the observation of incommensurable charge density wave (CDW) formed on the topological boundary states driven by the electron-electron interactions on the (001) surface of CoSi. The wavevector of CDW varies as the temperature changes, which coincides with the evolution of topological surface Fermi arcs with temperature. The orientation of the CDW phase is determined by the chirality of the Fermi arcs, which indicates a direct association between CDW and Fermi arcs. Our finding will stimulate the search of more interactions-driven ordered states, such as superconductivity and magnetism, on the boundaries of topological materials.

LRP6 Bidirectionally Regulates Insulin Sensitivity through Insulin Receptor and S6K Signaling in Rats with CG-IUGR.

OBJECTIVE: Intrauterine growth restriction followed by postnatal catch-up growth (CG-IUGR) increases the risk of insulin resistance-related diseases. Low-density lipoprotein receptor-related protein 6 (LRP6) plays a substantial role in glucose metabolism. However, whether LRP6 is involved in the insulin resistance of CG-IUGR is unclear. This study aimed to explore the role of LRP6 in insulin signaling in response to CG-IUGR. METHODS: The CG-IUGR rat model was established via a maternal gestational nutritional restriction followed by postnatal litter size reduction. The mRNA and protein expression of the components in the insulin pathway, LRP6/ß-catenin and mammalian target of rapamycin (mTOR)/S6 kinase (S6K) signaling, was determined. Liver tissues were immunostained for the expression of LRP6 and ß-catenin. LRP6 was overexpressed or silenced in primary hepatocytes to explore its role in insulin signaling. RESULTS: Compared with the control rats, CG-IUGR rats showed higher homeostasis model assessment for insulin resistance (HOMA-IR) index and fasting insulin level, decreased insulin signaling, reduced mTOR/S6K/ insulin receptor substrate-1 (IRS-1) serine307 activity, and decreased LRP6/ß-catenin in the liver tissue. The knockdown of LRP6 in hepatocytes from appropriate-for-gestational-age (AGA) rats led to reductions in insulin receptor (IR) signaling and mTOR/S6K/IRS-1 serine307 activity. In contrast, LRP6 overexpression in hepatocytes of CG-IUGR rats resulted in elevated IR signaling and mTOR/S6K/IRS-1 serine307 activity. CONCLUSION: LRP6 regulated the insulin signaling in the CG-IUGR rats via two distinct pathways, IR and mTOR-S6K signaling. LRP6 may be a potential therapeutic target for insulin resistance in CG-IUGR individuals.

ERα positively regulated DNMT1 expression by binding to the gene promoter region in human breast cancer MCF-7 cells.

Estrogen receptors (ER) are expressed in approximately 65% of human breast cancer. Clinical trials and retrospective analyses showed that ER-positive (ER+) tumors were more vulnerable to development of chemotherapy resistance than ER-negative (ER-) tumors. The underlying mechanism is still to be elucidated. Aberrant DNA methylation has been recognized to be associated with cancer chemotherapy resistance. Recently, steroid hormone and their receptors have been found to be involved in the regulation of methyltransferases (DNMTs) and thereby contribute to chemotherapy resistance. The purpose of this study is to explore whether ERα could directly regulate the DNMTs expression. We first analyzed the methylation alterations and its correlation with the expression levels of three types of DNMTs in our established paclitaxel-resistant breast cancer lines, MCF-7(ER+)/PTX and MDA-MB-231(ER-)/PTX cell lines, using qMSP, real-time PCR and Western blot. Then we determined the function of ERα in regulation of DNMT1 using luciferase report gene systems. Our data demonstrated for the first time that ERα could upregulate DNMT1 expression by directly binding to the DNMT1 promoter region in MFC-7(ER+)/PTX cells.

[The mbr-FPGS efficient expression plasmid enhances the sensitivity of Jurkat cells to methotrexate].

Folylpolyglutamate synthetase (FPGS) is the key enzyme that converts chemotherapy drug Methotrexate (MTX) into MTXPG. The expression level of FPGS directly influences MTX-sensitivity of tumor cells. Compared with B-cell acute lymphocytic leukemia (B-ALL), T-cell acute lymphocytic leukemia (T-ALL) cells express a lower level of FPGS, which results in insensitivity of the cells to MTX. Our previous work has demonstrated that 279 bp mbr element located within the 3'-UTR of the BCL2 gene possesses enhancer function. In this study, FPGS expression plasmid containing mbr element at the 5' upstream of the gene was constructed and transfected into Jurkat cells to sensitize the cells to MTX. Western blotting and MTT assay were applied to detect the FPGS expression level and suppression rate of the cells treated by MTX, respectively. We found that the mbr enhanced the expression of FPGS significantly and increased sensitivity of Jurkat cells to MTX efficiently, while FPGS expression plasmid without mbr element had less effect. Our data provides a new clue for the clinical application of mbr regulatory element and may contribute to improvement of MTX treatment in T-ALL.

[Resveratrol attenuates oxidant-induced mitochondrial damage in embryonic rat cardiomyocytes via inactivating GSK-3ß].

OBJECTIVE: To investigate the underlying mechanism of the protective effects of resveratrol on oxidant-induced mitochondrial damage in embryonic rat cardiomyocytes. METHODS: H9c2 cells, a permanent cell line derived from embryonic rat cardiac tissue, and then randomly divided into control group [PBS, cells exposed to H2O2 (600 µmol/L) for 20 min to induce mitochondrial oxidant damage], resveratrol group (0.01, 0.1, 1, 5, 10 and 20 µmol/L for 20 min at 20 min before exposing to H2O2), resveratrol plus inhibitor group (1 µmol/L KT5823 for 10 min at 10 min before 5 µmol/L resveratrol treatment) and inhibitor group (1 µmol/L KT5823 for 10 min). Mitochondrial membrane potential (ΔΨm) was measured by staining cells with tetramethylrhodamine ethyl ester (TMRE) and the mitochondrial permeability transition pore (mPTP) opening was evaluated by measuring the decrease of TMRE fluorescence intensity. Immunofluorescence assay was used to observe GSK-3ß phosphorylation. The phosphorylation of GSK-3ß and VASP were determined by Western blot. To detect intracellular NO, cells were loaded with DAF-FM DA (specific fluorescent dye of NO) and imaged with confocal microscopy. RESULTS: Compared to the control group, resveratrol (0.01-5 µmol/L) attenuated H2O2-induced mitochondrial damage reflected by attenuating the H2O2-induced TMRE fluorescence intensity decrease in a dose-dependent manner and the efficacy of 10 and 20 µmol/L resveratrol was significantly lower than that of 5 µmol/L resveratrol. Resveratrol also significantly upregulated the protein expression of VASP and increased GSK-3ß Ser(9) phosphorylation, which could lead the inactivation of GSK-3ß. These effects of resveratrol could be significantly abolished by protein kinase G inhibitor KT5823, while KT5823 alone did not affect GSK-3ß and VASP phosphorylation. Confocal microscopy showed that DAF-FM (specific NO indicator) was similar between resveratrol and control group, suggesting that resveratrol did not produce NO. CONCLUSIONS: Resveratrol could attenuate oxidant-induced mitochondrial damage in embryonic rat cardiomyocytes by inactivating GSK-3ß via cGMP/PKG signaling pathway independent of NO-related mechanism.

Mechanism and potential risk of antibiotic resistant bacteria carrying last resort antibiotic resistance genes under electrochemical treatment.

The significant rise in the number of antibiotic resistance genes (ARGs) that resulted from our abuse of antibiotics could do severe harm to public health as well as to the environment. We investigated removal efficiency and removal mechanism of electrochemical (EC) treatment based on 6 different bacteria isolated from hospital wastewater carrying 3 last resort ARGs including NDM-1, mcr-1 and tetX respectively. We found that the removal efficiency of ARGs increased with the increase of both voltage and electrolysis time while the maximum removal efficiency can reach 90%. The optimal treatment voltage and treatment time were 3 V and 120 min, respectively. Temperature, pH and other factors had little influence on the EC treatment process. The mechanism of EC treatment was explored from the macroscopic and microscopic levels by scanning electron microscopy (SEM) and flow cytometry. Our results showed that EC treatment significantly changed the permeability of cell membrane and caused cells successively experience early cell apoptosis, late cell apoptosis and cell necrosis. Moreover, compared with traditional disinfection methods, EC treatment had less potential risks. The conjugative transfer frequencies of cells were significantly reduced after treatment. Less than 1% of bacteria entered the viable but nonculturable (VBNC) state and less than 5% of intracellular ARGs (iARGs) turned into extracellular ARGs (eARGs). Our findings provide new insights into as well as important reference for future electrochemical treatment in removing ARB from hospital wastewater.

A Novel ATM Antisense Transcript ATM-AS Positively Regulates ATM Expression in Normal and Breast Cancer Cells.

OBJECTIVE: The ataxia telangiectasia mutated (ATM) gene is a master regulator in cellular DNA damage response. The dysregulation of ATM expression is frequent in breast cancer, and is known to be involved in the carcinogenesis and prognosis of cancer. However, the underlying mechanism remains unclear. The bioinformatic analysis predicted a potential antisense transcript ATM-antisense (AS) from the opposite strand of the ATM gene. The purpose of this study was to identify ATM-AS and investigate the possible effect of ATM-AS on the ATM gene regulation. METHODS: Single strand-specific RT-PCR was performed to verify the predicted antisense transcript ATM-AS within the ATM gene locus. qRT-PCR and Western blotting were used to detect the expression levels of ATM-AS and ATM in normal and breast cancer cell lines as well as in tissue samples. Luciferase reporter gene assays, biological mass spectrometry, ChIP-qPCR and RIP were used to explore the function of ATM-AS in regulating the ATM expression. Immunofluorescence and host-cell reactivation (HCR) assay were performed to evaluate the biological significance of ATM-AS in ATM-mediated DNA damage repair. Breast cancer tissue samples were used for evaluating the correlation of the ATM-AS level with the ATM expression as well as prognosis of the patients. RESULTS: The ATM-AS significantly upregulated the ATM gene activity by recruiting KAT5 histone acetyltransferase to the gene promoter. The reduced ATM-AS level led to the abnormal downregulation of ATM expression, and impaired the ATM-mediated DNA damage repair in normal breast cells in vitro. The ATM-AS level was positively correlated with the ATM expression in the examined breast cancer tissue samples, and the patient prognosis. CONCLUSION: The present study demonstrated that ATM-AS, an antisense transcript located within the ATM gene body, is an essential positive regulator of ATM expression, and functions by mediating the binding of KAT5 to the ATM promoter. These findings uncover the novel mechanism underlying the dysregulation of the ATM gene in breast cancer, and enrich our understanding of how an antisense transcript regulates its host gene.

[Differential gene expression of folylpolyglutamate synthetase in cytoplasm and mitochondria in acquired methotrexate enantiomers resistant to lung cancer A549 cell lines].

OBJECTIVE: To investigate the relationship between the resistance of methotrexate (MTX) enantiomer and the gene expression levels of folylpolyglutamate synthetase (FPGS). METHODS: The cell lines of MTX enantiomer resistance from 15 - 55 µmol/L were obtained when the A549 cell lines were exposed intermittently and progressively to an incremental dose of each MTX enantiomer. The resistant index of MTX resistance cell lines were detected by MTT. The gene expressions of FPGS in cytoplasm and mitochondria were detected by real-time quantitative polymerase chain reaction (PCR). RESULTS: The resistance indice of D-(-)-MTX resistant cell lines were higher than those of L-(+)-MTX resistant cells (32.7 ± 9.3 vs 11.5 ± 2.9, P < 0.05). The resistant indice of L-(+)-MTX/A549 were from 5 to 15, which mean the middle resistance. The resistant indice of D-(-)-MTX/A549 were more than 15, which mean the severe resistance. The expression of mFPGS had difference between resistant cell lines of L-(+) and D-(-)-MTX except at 15 µmol/L MTX (at 25 µmol/L, 1.3 ± 0.7 vs. 2.3 ± 0.9; at 35 µmol/L, 1.1 ± 0.9 vs. 2.6 ± 0.3; at 45 µmol/L, 1.0 ± 1.0 vs. 1.4 ± 0.8; at 55 µmol/L, 0.2 ± 0.1 vs. 1.0 ± 0.2; all P < 0.05). The expressions of cFPGS had no difference between resistant cell lines of L-(+) and D-(-)-MTX at 15 µmol/L MTX, while at 25 - 55 µmol/L, the cFPGS levels and resistance indice of D-(-)-MTX/A549 resistant cell lines showed a highly negative correlation (r = -0.95, P < 0.05). CONCLUSION: There may be a different mechanism between the first time treatment with 15 µmol/L dosage and the continual treatment with more than 25 µmol/L dosage in A549 cell lines. There had higher resistant index in D-(-)-MTX/A549 cell line than in L-(+)-MTX/A549 cell line. The results indicated that the difference in chirality should be considered in clinical treatment with MTX.

Behavior of antibiotic resistance genes in a wastewater treatment plant with different upgrading processes.

Wastewater treatment plants (WWTPs) in China have been upgraded or renovated with a variety of emerging processes, but a comprehensive understanding of the behavior of antibiotic resistance genes (ARGs) in these WWTPs is still lacking. Here, the distribution of ARGs and bacterial community were investigated in a wastewater treatment plant with upgrading processes (WWTP-UP). 238 unique ARGs were detected in all samples. During the study period, the average ARGs concentration decreased by 98.4% along the entire treatment process. The removal efficiency of A2/O-membrane bioreactor (MBR) process was significantly higher than that of A2/O-high efficiency flocculent settling/cloth media filter (HEFS/CMF) process (p < 0.05), which corresponded to 3.5 and 2.1 log values on average, respectively. Notably, 35 ARGs and 14 mobile genetic elements (MGEs) were persistent in all samples. Based on the co-occurrence pattern revealed by network analysis, persistent ARGs possibly spread through the transfer of persistent MGEs among persistent bacteria. Using multiple linear regression analysis, we obtained 3 to 5 possible indicators for major ARG types, which might be served to evaluate the general distribution of ARGs or even predict the abundance of different ARG types. Our findings provide new insights into the impacts of upgrading process on ARGs and highlight the need for better strategies to improve ARGs elimination in WWTPs.

Landscape of genes in hospital wastewater breaking through the defense line of last-resort antibiotics.

Hospital wastewater contains abundant antibiotics, antibiotic resistance genes (ARGs), and pathogens. Last-resort antibiotic resistance genes (LARGs) include the New Delhi metallo-ß-lactamase gene blaNDM, mobile colistin resistance gene mcr and tigecycline resistance gene tet(X) which confers resistance to carbapenems, colistin and tigecycline. The presence and significance of LARGs in hospital wastewater treatment systems (HWTS) have not yet been systematically explored. Here, LARG variants were shown to be prevalent both influents and effluents of HWTS. A total of 989 Enterobacteriaceae isolates that confer resistance to last-resort antibiotics were collected from effluents and multiple genetic contexts of LARGs were analyzed. LARGs-carrying plasmids were confirmed to show high multidrug phenotypes and transferability. We also discovered the co-occurrence of plasmids harboring blaNDM-1 and mcr-1 in single Escherichia coli, as well as E. coli HM016 containing two unique mcr-1-carrying plasmids. This result might accelerate co-dissemination of LARGs under environmental selection pressure. Different core genetic arrangements in these strains suggest several evolutionary pathways in HWTS. The resistance functions of LARGs were confirmed in vitro and in vivo by mass spectrometry. This study provides novel insights into the diversity, genetic context and function of critical ARGs in HWTS. The results raise the concern that LARGs may further spread into the environment, thus, more stringent discharge standards and regulations for hospital wastewater are urgently needed.

Spread of antibiotic resistance genes and microbiota in airborne particulate matter, dust, and human airways in the urban hospital.

Antimicrobial resistance is an increasingly serious threat to public health worldwide. The presence of antibiotic resistance genes (ARGs) in human airways and relevant environments has not received significant attention. In this study, abundances of ARGs and microbes from airborne particulate matter, dust, and human airways in a hospital were profiled using high-throughput qPCR and 16S rRNA gene sequencing. More diverse ARGs and microbes in indoor dust and higher levels of ARGs in particulate matter PM10 and PM2.5 were observed. Macrolides and aminoglycoside resistance genes were the most abundant ARGs in the airway and environmental samples, respectively. Moreover, the co-occurrences of priority pathogens, ARGs, and mobile genetic elements (MGEs) were shown by the Network analysis. Campylobacter spp. and Staphylococcus spp. positively correlated with fluoroquinolone (vatC-02, mexD) and ß-lactams (blaZ, mecA) resistance genes, respectively. In this regard, based on SourceTracker analysis, inhalable particles contributed to 4.0% to 5.5% of ARGs in human airway samples, suggesting an important exchange between airborne inhalable particles and human commensals. This study may advance knowledge about ARGs in airborne particulate matter and dust associated environments, reveal their potential link between environments and humans, and provide a new sight and fundamental data for ARG risk assessment.