ABSTRACT
Oxidative damage caused by the accumulation of reactive oxygen species (ROS) is one of the main obstacles to the improvement of microbial cell growth and fermentation characteristics under adverse environments. And the antioxidant capacity of cells will increase with the cell growth. Here, we found that a transition state transcription factor AbrB related to changes in cell growth status could regulate the accumulation of ROS and antioxidant capacity in Bacillus licheniformis. The results showed that the accumulation of intracellular ROS was reduced by 23.91â¯% and the cell survival rates were increased by 1.77-fold under 0.5â¯mM H2O2 when AbrB was knocked out. We further mapped regulatory target genes of AbrB related to ROS generation or clearance based on our previously analyzed transcriptome sequencing. It proved that AbrB could promote ROS generation via upregulating the synthesis of oxidase and siderophores, and negatively regulating the synthesis of iron chelators (pulcherriminic acid, and H2S). Additionally, AbrB could inhibit ROS clearance by negatively regulating the synthesis of antioxidase (superoxide dismutase, catalase, peroxidase, thioredoxin, thioredoxin reductase) and cysteine. Those results illustrated that the inactivation of AbrB during the stationary phase, along with its control over ROS generation and clearance, might represent a vital self-protection mechanism during cell evolution. Overall, the systematic investigation of the multi-pathway regulation network of ROS generation and clearance highlights the important function of AbrB in maintaining intracellular redox balance.
ABSTRACT
BACKGROUND: Despite the global increase in the adoption of robotic natural orifice specimen extraction surgery (R-NOSES), its advantages over robotic transabdominal specimen extraction surgery (R-TSES) for treating early-stage rectal cancer remain debated. There is scant nationwide, multicenter studies comparing the surgical quality and short-term outcomes between R-NOSES and R-TSES for this condition. OBJECTIVE: This retrospective cohort study was conducted nationally across multiple centers to compare the surgical quality and short-term outcomes between R-NOSES and R-TSES in early-stage rectal cancer. DESIGN: Multicenter retrospective cohort trial. SETTING: Eight experienced surgeons from 8 high-volume Chinese colorectal cancer treatment centers. PATIENTS: The study included 1086 patients who underwent R-NOSES or R-TSES from October 2015 to November 2023 at the 8 centers. Inclusion criteria were: (1) histologically confirmed rectal adenocarcinoma; (2) robotic total mesorectal excision; (3) postoperative pathological staging of TisN0M0 or T1-2N0M0; (4) availability of complete surgical and postoperative follow-up data. Patients were matched 1:1 in the R-NOSES and R-TSES groups using the propensity score matching (PSM) technique. RESULTS: After PSM, 318 matched pairs with well-balanced patient characteristics were identified. The operation time for the R-NOSES group was significantly longer than that for the R-TSES group [140 min (125-170 min) vs. 140 min (120-160 min), P = 0.032]. Conversely, the times to first flatus and initial oral intake in the R-NOSES group were significantly shorter than those in the R-TSES group [48 h (41-56 h) vs. 48 h (44-62 h), P = 0.049 and 77 h (72-94 h) vs. 82 h (72-96 h), P = 0.008], respectively. Additionally, the length of postoperative hospital stay was shorter in the R-NOSES group compared with the R-TSES group [7 day (7-9 day) vs. 8 day (7-9 day), P = 0.005]. The overall postoperative complication rates were similar between the groups (10.7% in the R-NOSES group vs. 11.9% in the R-TSES group, P = 0.617). However, the R-NOSES group had a lower incidence of wound complications compared to the R-TSES group (0.0% vs. 2.2%, P = 0.015). Regarding surgical stress response, the R-NOSES group showed superior outcomes. Additionally, patients in the R-NOSES group required fewer additional analgesics on postoperative days 1, 3, and 5 and reported lower pain scores compared to the R-TSES group. The body image scale (BIS) and cosmetic scale (CS) scores were also significantly higher in the R-NOSES group. Furthermore, the R-NOSES group demonstrated significantly better outcomes in functional dimensions such as physical, role, emotional, social, and cognitive functioning, and in symptoms like fatigue and pain, when compared to the R-TSES group. LIMITATIONS: It is imperative to ensure the safe and standardized implementation of R-NOSES through the establishment of a uniform training protocol. CONCLUSIONS: These results affirm that R-NOSES is a safe and effective treatment for early-stage rectal cancer when meticulously executed by skilled surgeons.
Subject(s)
Natural Orifice Endoscopic Surgery , Propensity Score , Rectal Neoplasms , Robotic Surgical Procedures , Humans , Rectal Neoplasms/surgery , Rectal Neoplasms/pathology , Robotic Surgical Procedures/methods , Female , Male , Retrospective Studies , Middle Aged , China/epidemiology , Natural Orifice Endoscopic Surgery/methods , Aged , Neoplasm Staging , Operative Time , Adenocarcinoma/surgery , Adenocarcinoma/pathology , Adult , Length of Stay/statistics & numerical data , Treatment OutcomeABSTRACT
Bacillus spp., a class of aerobic bacteria, is widely used as a biocontrol microbe in the world. However, the reactive oxygen species (ROS) will accumulate once the aerobic bacteria are exposed to environmental stresses, which can decrease cell activity or lead to cell death. Hydroxyl radical (·OH), the strongest oxide in the ROS, can damage DNA directly, which is generated through Fenton Reaction by H2O2 and free iron. Here, we proved that the synthesis of pulcherriminic acid (PA), an iron chelator produced by Bacillus spp., could reduce DNA damage to protect cells from oxidative stress by sequestrating excess free iron, which enhanced the cell survival rates in stressful conditions (salt, antibiotic, and high temperature). It was worth noting that the synthesis of PA was found to be increased under oxidative stress. Thus, we demonstrated that the YvmB, a direct negative regulator of PA synthesis cluster yvmC-cypX, could be oxidized at cysteine residue (C57) to form a dimer losing the DNA-binding activity, which led to an improvement in PA production. Collectively, our findings highlight that YvmB senses ROS to regulate PA synthesis is one of the evolved proactive defense systems in bacteria against adverse environments.IMPORTANCEUnder environment stress, the electron transfer chain will be perturbed resulting in the accumulation of H2O2 and rapidly transform to ·OH through Fenton Reaction. How do bacteria deal with oxidative stress? At present, several iron chelators have been reported to decrease the ·OH generation by sequestrating iron, while how bacteria control the synthesis of iron chelators to resist oxidative stress is still unclear. Our study found that the synthesis of iron chelator PA is induced by reactive oxygen species (ROS), which means that the synthesis of iron chelator is a proactive defense mechanism against environment stress. Importantly, YvmB is the first response factor found to protect cells by reducing the ROS generation, which present a new perspective in antioxidation studies.
Subject(s)
Bacillus licheniformis , Bacillus , Reactive Oxygen Species/metabolism , Bacillus licheniformis/metabolism , Hydrogen Peroxide , Oxidative Stress , Iron/metabolism , Iron Chelating Agents , Bacillus/metabolism , DNA/metabolismABSTRACT
Induction of antigen-specific immune tolerance for the treatment of allergic or autoimmune diseases is an attractive strategy. Herein, we investigated the protective effect of a transdermal microneedle patch against allergic asthma by stimulating allergen-specific immune tolerance. We fabricated biodegradable tolerogenic nanoparticles (tNPs) that are loaded with a model allergen ovalbumin (OVA) and an immunomodulator rapamycin, and filled the tNPs into microneedle tips by centrifugation to form sustained-release microneedles. After intradermal immunization, the microneedles successfully delivered the cargos into the skin and sustainedly released them for over 96 h. Importantly, the microneedles induced allergen-specific regulatory T cells (Treg), decreased the levels of pro-inflammatory cytokines and antibodies while increased anti-inflammation cytokines, finally leading to restored immune homeostasis. The lung tissue analysis illustrated that the sustained-release microneedles significantly reduced the infiltration of eosinophils, decreased the accumulation of mucus and collagen, and significantly relived asthma symptoms. Our results suggested that the sustained-release microneedle-based transdermal delivery system can induce antigen-specific immune tolerance with improved compliance and efficacy, providing a new therapeutic strategy for the treatment of allergic and autoimmune diseases.
Subject(s)
Asthma , Autoimmune Diseases , Hypersensitivity , Nanoparticles , Humans , Delayed-Action Preparations , Asthma/drug therapy , Immune Tolerance , Allergens , CytokinesABSTRACT
Metal oxide semiconductor (MOS)-based complementary thin-film transistor (TFT) circuits have broad application prospects in large-scale flexible electronics. To simplify circuit design and increase integration density, basic complementary circuits require both p- and n-channel transistors based on an individual semiconductor. However, until now, no MOSs that can simultaneously show p- and n-type conduction behavior have been reported. Herein, we demonstrate for the first time that Cu-doped SnO (Cu:SnO) with HfO2 capping can be employed for high-performance p- and n-channel TFTs. The interstitial Cu+ can induce an n-doping effect while restraining electron-electron scatterings by removing conduction band minimum degeneracy. As a result, the Cu3 atom %:SnO TFTs exhibit a record high electron mobility of 43.8 cm2 V-1 s-1. Meanwhile, the p-channel devices show an ultrahigh hole mobility of 2.4 cm2 V-1 s-1. Flexible complementary logics are then established, including an inverter, NAND gates, and NOR gates. Impressively, the inverter exhibits an ultrahigh gain of 302.4 and excellent operational stability and bending reliability.
ABSTRACT
Restoring immune tolerance is the ultimate goal for rheumatoid arthritis (RA) treatment. The most reported oral or intravenous injection routes for the immunization of autoantigens cause gastrointestinal side effects, low patient compliance, and unsatisfied immune tolerance induction. Herein, the use of a transdermal microneedle patch is for the first time investigated to codeliver CII peptide autoantigen and rapamycin for reversing immune disorders of RA. The immunized microneedles efficiently recruit antigen-presenting cells particularly Langerhans cells, and induce tolerogenic dendritic cells at the administration skin site. The tolerogenic dendritic cells further homing to lymph nodes to activate systemic Treg cell differentiation, which upregulates the expression of anti-inflammatory mediators while inhibiting the polarization of Th1/2 and Th17 T cell phenotypes and the expression of inflammatory profiles. As a result, the optimized microneedles nearly completely eliminate RA symptoms and inflammatory infiltrations. Furthermore, it is demonstrated that a low dose of rapamycin is crucial for the successful induction of immune tolerance. The results indicate that a rationally designed microneedle patch is a promising strategy for immune balance restoration with increased immune tolerance induction efficiency and patient compliance.
Subject(s)
Arthritis, Rheumatoid , Langerhans Cells , Humans , Th17 Cells , Arthritis, Rheumatoid/therapy , Immune Tolerance , Sirolimus/pharmacologyABSTRACT
Intrahepatic cholangiocarcinoma (ICC) accounts for 20% of liver malignancies with a 5-year survival rate of 35% at best with limited prognostic predictors. Lung Immune Prognostic Index (LIPI) is a novel prognostic factor in pulmonary cancers. In this study, we developed a modified prognostic model from LIPI called intrahepatic immune prognostic index (IIPI) for ICC. A retrospectively study was conducted at Liver Transplant Center of West China Hospital between January 2015 and January 2023. Hematological factors and clinical features of ICC patients were collected and analyzed. The area under curve (AUC) and optimal cuff-off of each single hematological factor was calculated. In this study, derived neurtrophil to lymphocyte ratio (dNLR), arbohydrate antigen199 (CA199) and carcinoembryonic antigen (CEA) have higher AUC values. LIPI was composed of dNLR and was further modified by combing CA199 and CEA, forming the IIPI. The IIPI consists of four grades which are None, Light, Moderate and Severe. Compared to other prognostic factors, IIPI exhibited better ability to predict overall survival. The multivariate analysis indicated that cirrhosis, differentiation, hilar invasion and IIPI were independent prognostic factors for ICC patients. An IIPI-based nomogram was also established and could predict the overall survival. In addition, the subgroup analyses based on clinical prognostic factors showed that the IIPI exhibited excellent prognostic influence. IIPI model is suitable for predicting the prognosis of postoperative ICC patients. Further research is needed to explore the relationship between postoperative recurrence and metastasis of ICC patients and IIPI.
Subject(s)
Bile Duct Neoplasms , Cholangiocarcinoma , Humans , Carcinoembryonic Antigen , Retrospective Studies , Prognosis , Cholangiocarcinoma/pathology , Bile Ducts, Intrahepatic/pathology , Bile Duct Neoplasms/surgery , Bile Duct Neoplasms/pathologyABSTRACT
BACKGROUND: Robotic resection using the natural orifice specimen extraction surgery I-type F method (R-NOSES I-F) is a novel minimally invasive surgical strategy for the treatment of lower rectal cancer. However, the current literature on this method is limited to case reports, and further investigation into its safety and feasibility is warranted. AIM: To evaluate the safety and feasibility of R-NOSES I-F for the treatment of low rectal cancer. METHODS: From September 2018 to February 2022, 206 patients diagnosed with low rectal cancer at First Affiliated Hospital of Nanchang University were included in this retrospective analysis. Of these patients, 22 underwent R-NOSES I-F surgery (R-NOSES I-F group) and 76 underwent conventional robotic-assisted low rectal cancer resection (RLRC group). Clinicopathological data of all patients were collected and analyzed. Postoperative outcomes and prognoses were compared between the two groups. Statistical analysis was performed using SPSS software. RESULTS: Patients in the R-NOSES I-F group had a significantly lower visual analog score for pain on postoperative day 1 (1.7 ± 0.7 vs 2.2 ± 0.6, P = 0.003) and shorter postoperative anal venting time (2.7 ± 0.6 vs 3.5 ± 0.7, P < 0.001) than those in the RLRC group. There were no significant differences between the two groups in terms of sex, age, body mass index, tumor size, TNM stage, operative time, intraoperative bleeding, postoperative complications, or inflammatory response (P > 0.05). Postoperative anal and urinary functions, as assessed by Wexner, low anterior resection syndrome, and International Prostate Symptom Scale scores, were similar in both groups (P > 0.05). Long-term follow-up revealed no significant differences in the rates of local recurrence and distant metastasis between the two groups (P > 0.05). CONCLUSION: R-NOSES I-F is a safe and effective minimally invasive procedure for the treatment of lower rectal cancer. It improves pain relief, promotes gastrointestinal function recovery, and helps avoid incision-related complications.
ABSTRACT
Blood and lymph are two main pathways of tumor metastasis; however, hematogenous metastasis and lymphatic metastasis are difficult to inhibit simultaneously. Ferroptosis provides a new breakthrough for metastasis inhibition, but how to effectively trigger ferroptosis in tumor cells remains a major challenge. Metastatic tumor cells are prone to ferroptosis in blood, while they may be protected from ferroptosis in lymph. In this study, a nanoplatform DA/RSL3 was constructed for the intracellular codelivery of the polyunsaturated arachidonic acid (AA) and the GPX4 inhibitor RSL3, which could not only induce ferroptosis but also alleviate ferroptosis resistance. As a result, DA/RSL3 effectively triggered ferroptosis in tumor cells, thereby impairing the ability of tumor cells to metastasize in both blood and lymph. Furthermore, a fucoidan blocking strategy was proposed to maximize the efficacy of DA/RSL3. Fu+DA/RSL3 showed excellent efficacy in 4T1 tumor-bearing mice. This ferroptosis nanotherapy is promising for metastatic cancer treatment.
Subject(s)
Ferroptosis , Mice , Animals , Phospholipid Hydroperoxide Glutathione Peroxidase/metabolism , Phospholipid Hydroperoxide Glutathione Peroxidase/pharmacology , Lymphatic MetastasisABSTRACT
Lichenysin, a cyclic lipopeptide biosurfactant produced by Bacillus licheniformis, is composed of aspartate, glutamine, valine, leucine, isoleucine, and branched chain fatty acids. The synthesis of these amino acids and fatty acids requires pyruvate and NADPH as the primary precursor and cofactor. Therefore, a sufficient supply of pyruvate and NADPH is crucial for lichenysin production. This study aimed to increase lichenysin production by constructing a synthetic ED pathway in B. licheniformis WX02 through introducing phosphogluconate dehydratase (encoded by gene edd) and 2-keto-3-deoxygluconate 6-phosphate aldolase (encoded by gene eda) from Escherichia coli. Additionally, the NADP+-dependent glucose-6-phosphate dehydrogenase (encoded by gene zwf) was overexpressed, resulting in an engineered strain WX02/pHY-edda(Ec)-zwf. Analysis of the fermentation process revealed that the concentrations of pyruvate, aspartate, glutamine, valine, leucine, branched-chain fatty acids (iC15:0, aC15:0, iC16:0, iC17:0), and NADPH in WX02/pHY-edda(Ec)-zwf were increased by 77.21%, 80.41%, 85.31%, 141.64%, 44.94%, 35.08%, 38.08%, 19.33%, 21.16%, and 425%, respectively, compared to the control strain WX02/pHY300, which resulted in a 45.43% increase of lichenysin titer. This work took advantage of the ED pathway to increase lichenysin production for the first time, and provides a promising strategy for boosting the productivity of biochemicals that require pyruvate and NADPH as precursor and cofactor.
Subject(s)
Bacillus licheniformis , Bacillus licheniformis/genetics , Bacillus licheniformis/metabolism , Glutamine/metabolism , Aspartic Acid/metabolism , Leucine , NADP/metabolism , Peptides, Cyclic , Valine , Pyruvates/metabolism , Fatty Acids/metabolismABSTRACT
Metabolic engineering is a substantial approach for escalating the production of biochemical products. Cell biomass is lowered by system constraints and toxication carried on by the aggregation of metabolites that serve as inhibitors of product synthesis. In order to increase the production of biochemical products, it is important to trace the relationship between alanine metabolism and biomass. According to our investigation, the appropriate concentration of additional L/D-alanine (0.1 g/L) raised the cell biomass (OD600) in Bacillus licheniformis in contrast to the control strain. Remarkably, it was also determined that high levels of intracellular L/D-alanine and D-alanyl-D-alanine were induced by the overexpression of the ald, dal, and ddl genes to accelerate cell proliferation. Our findings clearly revealed that 0.2 g/L of L-alanine and D-alanine substantially elevated the titer of poly-γ-glutamic acid (γ-PGA) by 14.89% and 6.19%, correspondingly. And the levels of γ-PGA titer were hastened by the overexpression of the ald, dal, and ddl genes by 19.72%, 15.91%, and 16.64%, respectively. Furthermore, overexpression of ald, dal, and ddl genes decreased the by-products (acetoin, 2,3-butanediol, acetic acid and lactic acid) formation by about 14.10%, 8.77%, and 8.84% for augmenting the γ-PGA production. Our results also demonstrated that overexpression of ald gene amplified the production of lichenysin, pulcherrimin and nattokinase by about 18.71%, 19.82% and 21.49%, respectively. This work delineated the importance of the L/D-alanine and D-alanyl-D-alanine synthesis to the cell growth and the high production of bio-products, and provided an effective strategy for producing bio-products.
Subject(s)
Bacillus licheniformis , Bacillus licheniformis/genetics , Bacillus licheniformis/metabolism , Metabolic Engineering , Acetic Acid/metabolism , Polyglutamic Acid/metabolismABSTRACT
The biosynthetic pathway of eicosapentaenoic acid (EPA) has previously been reported in marine bacteria, while the regulatory mechanism remains poorly understood. In this study, a putative transcriptional regulator PfaR encoded adjacent to the PFA biosynthesis gene cluster (pfaEABCD) was computationally and experimentally characterized. Comparative analyses on the wild type (WT) strain, in-frame deletion, and overexpression mutants revealed that PfaR positively regulated EPA synthesis at low temperature. RNA-Seq and real-time quantitative PCR analyses demonstrated that PfaR stimulated the transcription of pfaABCD. The transcription start site of pfaR was mapped by using primer extension and highly conserved promoter motifs bound by the housekeeping Sigma 70 factor that were identified in the upstream of pfaR. Moreover, overexpression of PfaR in WT strain W3-18-1 at low temperature could improve EPA productivity from 0.07% to 0.13% (percentage of EPA to dry weight, mg/mg) of dry weight. Taken together, these findings could provide important implications into the transcriptional control and metabolic engineering in terms of EPA productivity for industrial strains. IMPORTANCE We have experimentally confirmed that PfaR is a positive transcription regulator that promotes EPA synthesis at low temperature in Shewanella putrefaciens W3-18-1. Overexpression of PfaR in WT strain W3-18-1 could lead to a 1.8-fold increase in EPA productivity at low temperature. It is further shown that PfaR may be regulated by housekeeping Sigma 70 factor at low temperature.
Subject(s)
Shewanella putrefaciens , Shewanella , Shewanella putrefaciens/genetics , Shewanella putrefaciens/metabolism , Eicosapentaenoic Acid/metabolism , Bacteria , Sequence Deletion , Biosynthetic Pathways/genetics , Shewanella/geneticsABSTRACT
Background: The aim of the study was to develop and validate a nomogram for predicting cancer-specific survival (CSS) in lymph- node- positive rectal cancer patients after radical proctectomy. Methods: In this study, we analyzed data collected from the Surveillance, Epidemiology, and End Results (SEER) database between 2004 and 2015. In addition, in a 7:3 randomized design, all patients were split into two groups (development and validation cohorts). CSS predictors were selected via univariate and multivariate Cox regressions. The nomogram was constructed by analyzing univariate and multivariate predictors. The effectiveness of this nomogram was evaluated by concordance index (C-index), calibration plots, and receiver operating characteristic (ROC) curve. Based on the total score of each patient in the development cohort in the nomogram, a risk stratification system was developed. In order to analyze the survival outcomes among different risk groups, Kaplan-Meier method was used. Results: We selected 4,310 lymph- node- positive rectal cancer patients after radical proctectomy, including a development cohort (70%, 3,017) and a validation cohort (30%, 1,293). The nomogram correlation C-index for the development cohort and the validation cohort was 0.702 (95% CI, 0.687-0.717) and 0.690 (95% CI, 0.665-0.715), respectively. The calibration curves for 3- and 5-year CSS showed great concordance. The 3- and 5-year areas under the curve (AUC) of ROC curves in the development cohort were 0.758 and 0.740, respectively, and 0.735 and 0.730 in the validation cohort, respectively. Following the establishment of the nomogram, we also established a risk stratification system. According to their nomogram total points, patients were divided into three risk groups. There were significant differences between the low-, intermediate-, and high-risk groups (p< 0.05). Conclusions: As a result of our research, we developed a highly discriminatory and accurate nomogram and associated risk classification system to predict CSS in lymph-node- positive rectal cancer patients after radical proctectomy. This model can help predict the prognosis of patients with lymph- node- positive rectal cancer.
ABSTRACT
Due to the insufficient long-term protection and significant efficacy reduction to new variants of current COVID-19 vaccines, the epidemic prevention and control are still challenging. Here, we employ a capsid and antigen structure engineering (CASE) strategy to manufacture an adeno-associated viral serotype 6-based vaccine (S663V-RBD), which expresses trimeric receptor binding domain (RBD) of spike protein fused with a biological adjuvant RS09. Impressively, the engineered S663V-RBD could rapidly induce a satisfactory RBD-specific IgG titer within 2 weeks and maintain the titer for more than 4 months. Compared to the licensed BBIBP-CorV (Sinopharm, China), a single-dose S663V-RBD induced more endurable and robust immune responses in mice and elicited superior neutralizing antibodies against three typical SARS-CoV-2 pseudoviruses including wild type, C.37 (Lambda) and B.1.617.2 (Delta). More interestingly, the intramuscular injection of S663V-RBD could overcome pre-existing immunity against the capsid. Given its effectiveness, the CASE-based S663V-RBD may provide a new solution for the current and next pandemic.
ABSTRACT
Hepatocellular carcinoma (HCC) is the fifth most common malignancy and the third most common cause of cancer-related death worldwide. Due to asymptomatic patients in the early stage, most patients are diagnosed at an advanced stage and lose the opportunity for radical resection. In addition, for patients who underwent procedures with curative intent for early-stage HCC, up to 70% of patients may have disease recurrence within 5 years. With the advent of an increasing number of systemic therapy medications, we now have more options for the treatment of HCC. However, data from clinical studies show that with different combinations of regimens, the objective response rate is approximately 40%, and most patients will not respond to treatment. In this setting, biomarkers for predicting treatment response are of great significance for precise treatment, reducing drug side effects and saving medical resources. In this review, we summarized the existing and emerging biomarkers in the literature, with special emphasis on the pathways and mechanism underlying the prediction value of those biomarkers for systemic treatment response.
ABSTRACT
The applications of thin-film transistors (TFTs) based on oxide semiconductors are limited due to instability under negative bias illumination stress (NBIS). Here, we report TFTs based on solution-processed In2O3 semiconductors doped with Pr4+ or Tb4+, which can effectively improve the NBIS stability. The differences between the Pr4+-doped In2O3 (Pr:In2O3) and Tb4+-doped In2O3 (Tb:In2O3) are investigated in detail. The undoped In2O3 TFTs with different annealing temperatures exhibit poor NBIS stability with serious turn-on voltage shift (ΔVon). After doping with Pr4+/Tb4+, the TFTs show greatly improved NBIS stability. As the annealing temperature increases, the Pr:In2O3 TFTs have poorer NBIS stability (ΔVon are -3.2, -4.8, and -4.8 V for annealing temperature of 300, 350, and 400 °C, respectively), while the Tb:In2O3 TFTs have better NBIS stability (ΔVon are -3.6, -3.6, and -1.2 V for annealing temperature of 300, 350, and 400 â, respectively). Further studies reveal that the improvement of the NBIS stability of the Pr4+/Tb4+:In2O3 TFTs is attributed to the absorption of the illuminated light by the Pr/Tb4fn-O2p6 to Pr/Tb 4fn+1-O2p5 charge transfer (CT) transition and downconversion of the light to nonradiative transition with a relatively short relaxation time compared to the ionization process of the oxygen vacancies. The higher NBIS stability of Tb:In2O3 TFTs compared to Pr:In2O3 TFTs is ascribed to the smaller ion radius of Tb4+ and the lower energy level of Tb 4f7 with a isotropic half-full configuration compared to that of Pr 4f1, which would make it easier for the Tb4+ to absorb the visible light than the Pr4+.
ABSTRACT
Lichenysin, producted by Bacillus licheniformis, is an important cyclic lipopeptide biosurfactant, which has potential applications in oil exploitation, drug development, biological control of agriculture and bioremediation. While studies are lacking on metabolism regulation of lichenysin biosynthesis, which limits metabolic engineering and large-scale production of lichenysin. In this study, the yield of lichenysin was improved obviously by 13.6 folds to 2.18 ± 0.03 g/L in degU deletion strain (WX02â³degU) compared with the wild-type strain (WX02) and completely inhibited in degU overexpressed strain (WX02/pHY-degU). We further proved that DegU, a transcription factor plays a significant role in multicellular behavior, is a key negative regulator of lichenysin synthesis lchA operon. But interestingly, lichenysin yield was still inhibited by overexpressing DegU in the promoter-substituted strain (WX02-PP43lch), in which promoter of lchA operon cannot be controlled by DegU. Thus, through 13C-metabolic flux analysis, we found that deletion of degU also enhanced glucose uptake, branched chain amino acid synthesis, and fatty acid synthesis, while decrease acetoin synthesis, which is beneficial for the supply of lichenysin precursors. Further experiments demonstrate that DegU regulates these pathways by binding to the promoter regions of related genes. Overall, we systematically investigated the multi-pathway regulation network mediated by DegU on lichenysin biosynthesis, which not only contributes to the further metabolic engineering for lichenysin high-production, but sheds light on studies of transcription factor regulation.
Subject(s)
Bacillus licheniformis , Bacillus licheniformis/genetics , Bacillus licheniformis/metabolism , Transcription Factors/genetics , Transcription Factors/metabolism , Lipoproteins/chemistry , Lipoproteins/genetics , Lipoproteins/metabolism , Anilides/metabolism , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Bacillus subtilis/metabolismABSTRACT
Accompanied with the developments of gene editing and synthetic biology toolkits, various metabolic engineering strategies have been established for strain improvement to enhance the target metabolite production. Poly-γ-glutamic acid (γ-PGA) is a natural biopolymer that mainly produced by Bacillus, and low-level yield hinders its application. To address this problem, numerous approaches have been conducted to increase γ-PGA yield. In this review, we focus on the genetic and metabolic engineering of microorganism for γ-PGA production, including strengthening raw materials utilization and precursor supply, enhancing γ-PGA synthetase gene cluster, transcription regulation engineering, cofactor regeneration, energy engineering and blocking the synthetic pathways of by-products. Meanwhile, to attain the γ-PGA with different configurations (D/L) and molecular weights, the expression of γ-PGA synthetase, glutamate racemase and γ-PGA hydrolase were respectively manipulated. In addition, except for Bacillus, metabolic engineering of other hosts for high-level production of γ-PGA was also reviewed in this article. Finally, the prospect of metabolic engineering of γ-PGA production strain was discussed regarding the recent progress, challenge, and trends in this field.
Subject(s)
Bacillus , Metabolic Engineering , Glutamic Acid , Ligases , Polyglutamic Acid/analogs & derivativesABSTRACT
Infrared organic photodiodes have gained increasing attention due to their great application potentials in night vision, optical communication, and all-weather imaging. However, the commonly occurring high dark current and low detectivity impede infrared photodetectors from portable applications at room temperature. Herein, an efficient and generic doping compensation strategy is developed to improve the detectivity of infrared organic photodiodes. A series of n-type organic semiconductors is investigated, and it is found that doping compensation strategy not only reduces the trap density of states and dark currents, but also restrains the nonradiative recombination with improved charge transport and collection. As a result, an ultralow noise spectral density of 8 × 10-15 A Hz-1/2 as well as a high specific detectivity over 1013 Jones in 780-1070 nm is achieved at room temperature. More importantly, the high-performance infrared organic photodiodes can be successfully applied in high-pixel-density image arrays without patterning sensing layers. These findings provide important compensation design insights that will be crucial to further improve the performance of infrared organic photodiodes in the future.
ABSTRACT
The study is aimed at investigating the effect of the FLOT2 gene on invasion and metastasis of colorectal cancer (CRC) cells and the corresponding molecular mechanism by preparing polylysine-silicon nanoparticles. Specifically, polylysine was used to modify the silica nanoparticles prepared by the emulsification method to obtain polylysine-silicon nanoparticles. The characterization of polylysine-silicon nanoparticles was completed by nanoparticle size analyzer, laser particle size potentiometer, and transmission microscope. The influence of polylysine-silicon nanoparticles on the survival rate of CRC cell line HT-29 was detected using the method of 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT). The FLOT2-siRNA expression vector was constructed and transfected with HT-29. The HT-29 transfected with empty plasmid was used as the negative control (NC). Western Blot (WB) and reverse transcription-polymerase chain reaction (RT-PCR) were used to detect expression levels of FLOT2 gene and epithelial-mesenchymal transition- (EMT-) related genes. Transwell invasion assay, Transwell migration assay, and CCK8 assay were used to detect the cell invasion, migration, and proliferation. The results showed that the average particle size of polylysine-silicon nanoparticles was 30 nm, the potential was 19.65 mV, the particle size was 65.8 nm, and the dispersion coefficient was 0.103. At the same concentration, the toxicity of silicon nanoparticles to HT-29 was significantly lower than that of liposome reagent, and the transfection efficiency was 60%, higher than that of liposome reagent (40%). The mRNA level and protein expression of the FLOT2 gene in the FLOT2-siRNA group were significantly lower than those in the NC group (P < 0.01). The optical density (OD) value of the NC group and the blank control (CK) group were significantly higher than that of FLOT2-siRNA cells (P < 0.01). The OD value of FLOT2-siRNA cells was lower than that of NC cells at 48 h, 72 h, and 96 h (P < 0.01). The mRNA levels and protein expressions of MMP2 and vimentin in the FLOT2-siRNA group were significantly lower than those in the NC group and CK group (P < 0.01). The mRNA level and protein expression of the E-cadherin gene in the FLOT2-siRNA group were significantly higher than those in the NC group and CK group (P < 0.01). In conclusion, an RNA interference plasmid with high transfection efficiency and low cytotoxicity was established based on nanotechnology. siRNA-mediated FLOT2 protein inhibits the invasion, migration, and proliferation of CRC cells by regulating the expression changes of EMT-related genes, which provides a scientific basis for clinical treatment of CRC.