The complete degradation of 1,2-dichloroethane in Escherichia coli by metabolic engineering.

1,2-Dichloroethane (1,2-DCA), a widely utilized chemical intermediate and organic solvent in industry, frequently enters the environment due to accidental leaks and mishandling during application processes. Thus, the in-situ remediation of contaminated sites has become increasingly urgent. However, traditional remediation methods are inefficient and costly, while bioremediation presents a green, efficient, and non-secondary polluting alternative. In this study, an engineered strain capable of completely degrading 1,2-DCA was constructed. We introduced six exogenous genes of the 1,2-DCA degradation pathway into E. coli and confirmed their normal transcription and efficient expression in this engineered strain through qRT-PCR and proteomics. The degradation experiments showed that the strain completely degraded 2 mM 1,2-DCA within 12 h. Furthermore, the results of isotope tracing verified that the final degradation product, malic acid, entered the tricarboxylic acid cycle (TCA) of E. coli and was ultimately fully metabolized. Also, morphological changes in the engineered strain and control strain exposed to 1,2-DCA were observed under SEM, and the results revealed that the engineered strain is more tolerant to 1,2-DCA than the control strain. In conclusion, this study paved a new way for humanity to deal with the increasingly complex environmental challenges.

Association between internal carotid artery kinking and ischemic stroke: A population-based cross-sectional study.

AIM: Evidence for an association between Internal carotid artery (ICA) kinking and ischemic stroke has been controversial. We aimed to examine the association between ICA tortuosity and risk of ischemic stroke and specific ischemic stroke subtypes (large artery atherosclerosis, LAA; small artery occlusion, SAO). METHODS: A total of 419 outpatients were included in this cross-sectional study. ICA kinking was objectively assessed by head and neck computed tomography angiography (CTA). The risk of ischemic stroke for each patient was evaluated according to the Essen Stroke Risk Score (ESRS). Ischemic stroke subtypes (LAA and SAO) were measure with head magnetic resonance imaging (MRI). RESULTS: The average age of patients was 59.1 years (SD = 13.25) and 264 (63.0 %) were males. The prevalence of ICA kinking in this sample was 31.5 % (132 out of 419). Individuals with ICA kinking was associated with 0.55-points increase in ESRS score than those without ICA kinking (95 % CI, 0.28-0.81, p < 0.001) among patients over 50 years. In addition, right ICA kinking or left ICA kinking were associated with 0.35-points (95 % CI, 0.08-0.63) and 0.49-points (95 % CI, 0.23-0.76) increase in ESRS score, respectively. For specific ischemic stroke subtypes, individuals with ICA kinking had a 10.34-fold increased risk of SAO compared to those without ICA kinking (95 % CI, 6.22-20.68). Individuals with right ICA kinking had a 4.51-fold risk of SAO than those without kinking (95 % CI, 2.64-7.71), and had an 8.86-fold risk of SAO than those without kinking in the left ICA kinking (95 % CI, 4.97-15.79). CONCLUSION: Our findings support the role of ICA kinking on ischemic stroke. Early screening and proper treatment of carotid artery tortuosity could be a potential intervention strategy for the prevention of ischemic stroke later on.

Creation of Environmentally Friendly Super "Dinitrotoluene Scavenger" Plants.

Pervasive environmental contamination due to the uncontrolled dispersal of 2,4-dinitrotoluene (2,4-DNT) represents a substantial global health risk, demanding urgent intervention for the removal of this detrimental compound from affected sites and the promotion of ecological restoration. Conventional methodologies, however, are energy-intensive, susceptible to secondary pollution, and may inadvertently increase carbon emissions. In this study, a 2,4-DNT degradation module is designed, assembled, and validated in rice plants. Consequently, the modified rice plants acquire the ability to counteract the phytotoxicity of 2,4-DNT. The most significant finding of this study is that these modified rice plants can completely degrade 2,4-DNT into innocuous substances and subsequently introduce them into the tricarboxylic acid cycle. Further, research reveals that the modified rice plants enable the rapid phytoremediation of 2,4-DNT-contaminated soil. This innovative, eco-friendly phytoremediation approach for dinitrotoluene-contaminated soil and water demonstrates significant potential across diverse regions, substantially contributing to carbon neutrality and sustainable development objectives by repurposing carbon and energy from organic contaminants.

Metabolic engineering of Escherichia coli for 2,4-dinitrotoluene degradation.

2,4-Dinitrotoluene (2,4-DNT) as a common industrial waste has been massively discharged into the environment with industrial wastewater. Due to its refractory degradation, high toxicity, and bioaccumulation, 2,4-DNT pollution has become increasingly serious. Compared with the currently available physical and chemical methods, in situ bioremediation is considered as an economical and environmentally friendly approach to remove toxic compounds from contaminated environment. In this study, we relocated a complete degradation pathway of 2,4-DNT into Escherichia coli to degrade 2,4-DNT completely. Eight genes from Burkholderia sp. strain were re-synthesized by PCR-based two-step DNA synthesis method and introduced into E. coli. Degradation experiments revealed that the transformant was able to degrade 2,4-DNT completely in 12 h when the 2,4-DNT concentration reached 3 mM. The organic acids in the tricarboxylic acid cycle were detected to prove the degradation of 2,4-DNT through the artificial degradation pathway. The results proved that 2,4-DNT could be completely degraded by the engineered bacteria. In this study, the complete degradation pathway of 2,4-DNT was constructed in E. coli for the first time using synthetic biology techniques. This research provides theoretical and experimental bases for the actual treatment of 2,4-DNT, and lays a technical foundation for the bioremediation of organic pollutants.

Early screening of nasopharyngeal carcinoma.

The low positive predictive value (PPV) of early screening of nasopharyngeal carcinoma (NPC) is the problems that need to be solved urgently. The combination of cell-free DNA (cfDNA) methylation testing and Epstein-Barr virus (EBV) serological testing is the key to solve this problem. This paper reviews recent advances in early screening for NPC and cfDNA methylation, with future perspectives. Pubmed was searched for the literature related to early screening of NPC and cfDNA methylation in the past 5 years. The results of these studies were summarized. Despite these efforts, the PPV is still low (10%). Previous studies have shown that cfDNA methylation analysis has good specificity and accuracy across a variety of tumors. The combination of cfDNA methylation and EBV detection helps to improve the PPV for early screening of NPC. The combination of cfDNA methylation and EBV serological testing is key to addressing the low PPV of NPC early screening.

Complete biodegradation of the oldest organic herbicide 2,4-Dichlorophenoxyacetic acid by engineering Escherichia coli.

After nearly 80 years of extensive application, the oldest organic herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) has caused many problems of environmental pollution and ecological deterioration. Bioremediation is an ideal method for pollutant treatment. However, difficult screening and preparation of efficient degradation bacteria have largely hindered its application in 2,4-D remediation. We have created a novel engineering Escherichia coli with a reconstructed complete degradation pathway of 2,4-D to solve the problem of screening highly efficient degradation bacteria in this study. The results of fluorescence quantitative PCR demonstrated that all nine genes in the degradation pathway were successfully expressed in the engineered strain. The engineered strains can quickly and completely degrade 0.5 mM 2, 4-D within 6 h. Inspiring, the engineered strains grew with 2,4-D as the sole carbon source. By using the isotope tracing method, the metabolites of 2,4-D were found incorporated into the tricarboxylic acid cycle in the engineering strain. Scanning electron microscopy showed that 2,4-D had less damage on the engineered bacteria than the wild-type strain. Engineered strain can also rapidly and completely remedy 2,4-D pollution in natural water and soil. Assembling the metabolic pathways of pollutants through synthetic biology was an effective method to create pollutant-degrading bacteria for bioremediation.

Genetic engineering of complex feed enzymes into barley seed for direct utilization in animal feedstuff.

Currently, feed enzymes are primarily obtained through fermentation of fungi, bacteria, and other microorganisms. Although the manufacturing technology for feed enzymes has evolved rapidly, the activities of these enzymes decline during the granulating process and the cost of application has increased over time. An alternative approach is the use of genetically modified plants containing complex feed enzymes for direct utilization in animal feedstuff. We co-expressed three commonly used feed enzymes (phytase, ß-glucanase, and xylanase) in barley seeds using the Agrobacterium-mediated transformation method and generated a new barley germplasm. The results showed that these enzymes were stable and had no effect on the development of the seeds. Supplementation of the basal diet of laying hens with only 8% of enzyme-containing seeds decreased the quantities of indigestible carbohydrates, improved the availability of phosphorus, and reduced the impact of animal production on the environment to an extent similar to directly adding exogenous enzymes to the feed. Feeding enzyme-containing seeds to layers significantly increased the strength of the eggshell and the weight of the eggs by 10.0%-11.3% and 5.6%-7.7% respectively. The intestinal microbiota obtained from layers fed with enzyme-containing seeds was altered compared to controls and was dominated by Alispes and Rikenella. Therefore, the transgenic barley seeds produced in this study can be used as an ideal feedstuff for use in animal feed.

Construction of complete degradation pathway for nitrobenzene in Escherichia coli.

Nitrobenzene is widely present in industrial wastewater and soil. Biodegradation has become an ideal method to remediate organic pollutants due to its low cost, high efficiency, and absence of secondary pollution. In the present study, 10 exogenous genes that can completely degrade nitrobenzene were introduced into Escherichia coli, and their successful expression in the strain was verified by fluorescence quantitative polymerase chain reaction and proteomic analysis. The results of the degradation experiment showed that the engineered strain could completely degrade 4 mM nitrobenzene within 8 h. The formation of intermediate metabolites was detected, and the final metabolites entered the E. coli tricarboxylic acid cycle smoothly. This process was discovered by isotope tracing method. Results indicated the integrality of the degradation pathway and the complete degradation of nitrobenzene. Finally, further experiments were conducted in soil to verify its degradation ability and showed that the engineered strain could also degrade 1 mM nitrobenzene within 10 h. In this study, engineered bacteria that can completely degrade nitrobenzene have been constructed successfully. The construction of remediation-engineered bacteria by synthetic biology laid the foundation for the industrial application of biological degradation of organic pollutants.

Metabolic engineering of Escherichia coli for direct production of vitamin C from D-glucose.

BACKGROUND: Production of vitamin C has been traditionally based on the Reichstein process and the two-step process. However, the two processes share a common disadvantage: vitamin C cannot be directly synthesized from D-glucose. Therefore, significant effort has been made to develop a one-step vitamin C fermentation process. While, 2-KLG, not vitamin C, is synthesized from nearly all current one-step fermentation processes. Vitamin C is naturally synthesized from glucose in Arabidopsis thaliana via a ten-step reaction pathway that is encoded by ten genes. The main objective of this study was to directly produce vitamin C from D-glucose in Escherichia coli by expression of the genes from the A. thaliana vitamin C biosynthetic pathway. RESULTS: Therefore, the ten genes of whole vitamin C synthesis pathway of A. thaliana were chemically synthesized, and an engineered strain harboring these genes was constructed in this study. The direct production of vitamin C from D-glucose based on one-step fermentation was achieved using this engineered strain and at least 1.53 mg/L vitamin C was produced in shaking flasks. CONCLUSIONS: The study demonstrates the feasibility of one-step fermentation for the production of vitamin C from D-glucose. Importantly, the one-step process has significant advantages compared with the currently used fermentation process: it can save multiple physical and chemical steps needed to convert D-glucose to D-sorbitol; it also does not involve the associated down-streaming steps required to convert 2-KLG into vitamin C.

Exosomal HMGA2 protein from EBV-positive NPC cells destroys vascular endothelial barriers and induces endothelial-to-mesenchymal transition to promote metastasis.

Increased vascular permeability facilitates metastasis. Cancer-secreted exosomes are emerging mediators of cancer-host crosstalk. Epstein-Barr virus (EBV), identified as the first human tumor-associated virus, plays a crucial role in metastatic tumors, especially in nasopharyngeal carcinoma (NPC). To date, whether and how exosomes from EBV-infected NPC cells affect vascular permeability remains unclear. Here, we show that exosomes from EBV-positive NPC cells, but not exosomes from EBV-negative NPC cells, destroy endothelial cell tight junction (TJ) proteins, which are natural barriers against metastasis, and promote endothelial-to-mesenchymal transition (EndMT) in endothelial cells. Proteomic analysis revealed that the level of HMGA2 protein was higher in exosomes derived from EBV-positive NPC cells compared with that in exosomes derived from EBV-negative NPC cells. Depletion of HMGA2 in exosomes derived from EBV-positive NPC cells attenuates endothelial cell dysfunction and tumor cell metastasis. In contrast, exosomes from HMGA2 overexpressing EBV-negative NPC cells promoted these processes. Furthermore, we showed that HMGA2 upregulates the expression of Snail, which contributes to TJ proteins reduction and EndMT in endothelial cells. Moreover, the level of HMGA2 in circulating exosomes is significantly higher in NPC patients with metastasis than in those without metastasis and healthy negative controls, and the level of HMGA2 in tumor cells is associated with TJ and EndMT protein expression in endothelial cells. Collectively, our findings suggest exosomal HMGA2 from EBV-positive NPC cells promotes tumor metastasis by targeting multiple endothelial TJ and promoting EndMT, which highlights secreted HMGA2 as a potential therapeutic target and a predictive marker for NPC metastasis.

Metabolic engineering of Oryza sativa for complete biodegradation of thiocyanate.

Industrial thiocyanate (SCN-) waste streams from gold mining and coal coking have caused serious environmental pollution worldwide. Phytoremediation is an efficient technology in treating hazardous wastes from the environment. However, the phytoremediation efficiency of thiocyanate is very low due to the fact that plants lack thiocyanate degradation enzymes. In this study, the thiocyanate hydrolase module was assembled correctly in rice seedlings and showed thiocyanate hydrolase activity. Rice seedlings engineered to express thiocyanate degrading activity were able to completely remove thiocyanate from coking wastewater. Our findings suggest that transforming the thiocyanate hydrolase module into plants is an efficient strategy for rapid phytoremediation of thiocyanate in the environment. Moreover, the rice seedlings expressing apoplastic or cytoplasmic targeted thiocyanate hydrolase module were constructed to compare the phytoremediation efficiency of secretory/intracellular recombinant thiocyanate hydrolase. The most obvious finding from this study is that the apoplastic expression system is more efficient than the cytoplasm expression system in the phytoremediation of thiocyanate. At last, this research also shows that the secreted thiocyanate hydrolase from engineered rice plants does not influence rhizosphere bacterial community composition.

Epstein-Barr Virus Induces Lymphangiogenesis and Lympth Node Metastasis via Upregulation of VEGF-C in Nasopharyngeal Carcinoma.

Lymphatic metastasis is a common clinical symptom in nasopharyngeal carcinoma (NPC), the most common Epstein-Barr virus (EBV)-associated head and neck malignancy. However, the effect of EBV on NPC lymph node (LN) metastasis is still unclear. In this study, we demonstrated that EBV infection is strongly associated with advanced clinical N stage and lymphangiogenesis of NPC. We found that NPC cells infected with EBV promote LN metastasis by inducing cancer-associated lymphangiogenesis, whereas these changes were abolished upon clearance of EBV genomes. Mechanistically, EBV-induced VEGF-C contributed to lymphangiogenesis and LN metastasis, and PHLPP1, a target of miR-BART15, partially contributed to AKT/HIF1a hyperactivity and subsequent VEGF-C transcriptional activation. In addition, administration of anti-VEGF-C antibody or HIF1α inhibitors attenuated the lymphangiogenesis and LN metastasis induced by EBV. Finally, we verified the clinical significance of this prometastatic EBV/VEGF-C axis by determining the expression of PHLPP1, AKT, HIF1a, and VEGF-C in NPC specimens with and without EBV. These results uncover a reasonable mechanism for the EBV-modulated LN metastasis microenvironment in NPC, indicating that EBV is a potential therapeutic target for NPC with lymphatic metastasis. IMPLICATIONS: This research demonstrates that EBV induces lymphangiogenesis in NPC by regulating PHLPP1/p-AKT/HIF1a/VEGF-C, providing a new therapeutic target for NPC with lymphatic metastasis.

Enhanced phytoremediation of TNT and cobalt co-contaminated soil by AfSSB transformed plant.

2,4,6-trinitrotoluene (TNT) and cobalt (Co) contaminants have posed a severe environmental problem in many countries. Phytoremediation is an environmentally friendly technology for the remediation of these contaminants. However, the toxicity of TNT and cobalt limit the efficacy of phytoremediation application. The present research showed that expressing the Acidithiobacillus ferrooxidans single-strand DNA-binding protein gene (AfSSB) can improve the tolerance of Arabidopsis and tall fescue to TNT and cobalt. Compared to control plants, the AfSSB transformed Arabidopsis and tall fescue exhibited enhanced phytoremediation of TNT and cobalt separately contaminated soil and co-contaminated soil. The comet analysis revealed that the AfSSB transformed Arabidopsis suffer reduced DNA damage than control plants under TNT or cobalt exposure. In addition, the proteomic analysis revealed that AfSSB improves TNT and cobalt tolerance by strengthening the reactive superoxide (ROS) scavenging system and the detoxification system. Results presented here serve as strong theoretical support for the phytoremediation potential of organic and metal pollutants mediated by single-strand DNA-binding protein genes. SUMMARIZES: This is the first report that AfSSB enhances phytoremediation of 2,4,6-trinitrotoluene and cobalt separately contaminated and co-contaminated soil.

Fc-specific and covalent conjugation of a fluorescent protein to a native antibody through a photoconjugation strategy for fabrication of a novel photostable fluorescent antibody.

Fluorophore-antibody conjugates with high photobleaching resistance, high chemical stability, and Fc-specific attachment is a great advantage for immunofluorescence imaging. Here, an Fc-binding protein (Z-domain) carrying a photo-cross-linker (p-benzoylphenylalanine, Bpa) fused with enhanced green fluorescent protein (EGFP), namely photoactivatable ZBpa-EGFP recombinant, was directly generated using the aminoacyl-tRNA synthetase/suppressor tRNA technique without any further modification. By employing the photoactivatable ZBpa-EGFP, an optimal approach was successfully developed which enabled EGFP to site-selectively and covalently attach to native antibody (IgG) with approximately 90% conjugation efficiency. After characterizing the Fc-specific and covalent manner of the EGFP-photoconjugated antibody, its excellent photobleaching resistance for immunofluorescence imaging was demonstrated in a model study by monitoring the toll-like receptor 4 (TLR4) expression in HepG2 cells. The proposed approach here for the preparation of a novel fluorescent antibody is available and reliable, which would play an important role in fluorescence immunoassay, and is expected to be extended to the generation of other biomolecule-photoconjugated antibodies, such as other fluorescent proteins for multiplex immunofluorescence imaging or reporter enzymes for highly sensitive enzyme immunoassays.Graphical abstract.

Confinement of Quantum Dots in between Monolayered Graphene Nanosheets for Arousing Boosted Multifarious Photoredox Selective Organic Transformation.

Transition metal chalcogenide quantum dots (TMC QDs) represent promising light-harvesting antennas because of their fascinating physicochemical properties including quantum confinement effect and suitable energy band structures. However, TMC QDs generally suffer from poor photoactivities and photostability due to deficiency of active sites and ultrafast recombination rate of photoinduced charge carriers. Here, we demonstrate how to rationally arouse the charge transfer kinetic of TMC QDs by close monolayered graphene (GR) encapsulation via a ligand-dominated layer-by-layer (LbL) assembly utilizing oppositely charged TMC QDs and GR nanosheets as the building blocks. The assembly units were spontaneously and intimately integrated in an alternate integration mode, thereby resulting in the multilayered three-dimensional (3D) TMC QDs/GR ensembles. It was unveiled that multifarious photoactivities of TMC QDs/GR nanocomposites toward versatile photoredox organic catalysis including photocatalytic aromatic alcohols oxidation to aldehydes and nitroaromatics reduction to amino derivatives under visible light irradiation are conspicuously boosted because of spatially multilayered monolayered GR encapsulation which are superior to those of TMC QDs counterparts. The substantially enhanced photoactivities of TMC QDs/GR nanocomposites arise from reasons including improved light absorption and enhanced charge separation efficacy because of GR encapsulation together with unique stacking mode between TMC QDs and GR endowed by LbL assembly. Our work would provide a promising and efficacious route to smartly accelerate the charge transfer kinetic of TMC QDs for solar energy conversion.

Maneuvering Intrinsic Instability of Metal Nanoclusters for Boosted Solar-Powered Hydrogen Production.

Atomically precise metal nanoclusters (NCs) have recently been unleashed as novel photosensitizers but inevitably suffer from light-induced self-transformation to metal nanocrystals (NYs), leading to substantially reduced photoredox activities. Herein, we conceptually demonstrate how to manipulate the intrinsic instability of metal NCs for smartly crafting long-range cascade charge transfer chain assisted by an ultrathin poly(dialyldimethylammonium chloride) (PDDA) layer that was intercalated at the interface of metal NCs and semiconductor. The unidirectional electron flow endowed by Schottky-type self-transformed metal NYs and unexpected electron-withdrawing capability of PDDA layer concurrently foster the charge transfer cascade, resulting in the markedly enhanced net efficiency of photocatalytic hydrogen evolution performances under visible light irradiation. Our work opens new frontiers for judiciously harnessing the inherent detrimental instability of metal NCs for boosted charge transfer toward solar-to-hydrogen conversion.

[Effects of Radix Angelicae Sinensis on airway mucus hypersecretion and the TNF-α/NF-κB signaling pathway in Yin-deficiency asthmatic mice].

Objective: To investigate the therapeutic effects of Radix Angelicae Sinensis (RADA) on airway mucus hypersecretion and the tumor necrosis factor-α/ nuclear factor- κB (TNF-α/NF-κB) signaling pathway in Yin-deficiency asthma mice. Methods: KM mice were randomly divided into control group, model group, ambroxol group and RADA low, medium and high dose (2, 4 and 8 g/kg) group(n=12). Ovalbumin and the thyroid gland were used to replicate the model of Yin-deficiency asthma. Asthma symptoms in mice , immune globulin E (IgE) , TNF-α , and the expressions of Mucin 5ac (Muc5ac) and NF- κB in lung tissue were observed under the intervention of RADA. Results: RADA at the doses of 2,4 and 8 g/kg could alleviate the asthma symptoms of Yin-deficiency asthma mice significantly, reduce the levels of IgE in serum and TNF-α in bronchoalveolar lavage fluid (BALF), and inhibite the overexpressions of Muc5ac and NF- κB in lung tissue. Conclusion: RADA has significant anti-asthmatic effect. One of its mechanisms is to inhibit TNF-α/NF- κB signaling pathway and to alleviate airway mucus hypersecretion.

[Clinical features, diagnosis, and treatment of Chinese children with Shwachman-Diamond syndrome].

In order to clearly define the features of Shwachman-Diamond syndrome (SDS) in Chinese children, this article analyzes and summarizes the epidemiology, clinical features, and key points in the diagnosis and treatment of SDS in Chinese children with review of the clinical data of 27 children with SDS from related articles published previously. A comparative analysis was made between the Chinese and international data related to childhood SDS. The results showed a male/female ratio of about 2:1 in the Chinese children with SDS, with an age of onset of <1 month to 5 years (median 1 month) and an age of 3 months to 12 years (median 12 months) at the time of confirmed diagnosis. Reductions in peripheral blood cells due to myelopoiesis inhibition were observed in all 27 children with SDS, among whom 93% had neutropenia. Chronic diarrhea (85%), liver damage (78%), and short stature (83%) were the three main clinical features of SDS. Supplementation of pancreatin and component blood transfusion may temporarily alleviate the disease, while allogeneic hematopoietic stem cell transplantation is still an effective radical treatment. The comparative analysis of the Chinese and oversea data showed that compared with those in the European and American countries, the children with SDS in China had significantly higher incidence rates of chronic diarrhea, reductions in peripheral blood cells (three lineages), and liver damage, and there were also differences in the type of mutant genes.