Extremely acidic conditions (pH < 1.0) during hydrogen sulfide (H2S) biotreatment significantly reduce the cost of pH regulation; however, there remain challenges to its applications. The present ...study investigated the H2S removal and biomass variations in biotrickling filter (BTF) under long-term highly acidic conditions. A BTF operated for 144 days at pH 0.5–1.0 achieved an H2S elimination capacity (EC) of 109.9 g/(m3·h) (removal efficiency = 97.0%) at an empty bed retention time of 20 s, with an average biomass concentration at 20.6 g/L-BTF. The biomass concentration at neutral pH increased from 22.3 to 49.5 g/L-BTF within 28 days. In this case, elemental sulfur (S0) accumulated due to insufficient oxygen transfer in biofilm, which aggravated the BTF blockage problem. After long-term domestication under extremely acidic conditions, a mixotrophic acidophilic sulfur-oxidizing bacteria (SOB) Alicyclobacillus (abundance 55.4%) were enriched in the extremely acidic biofilm, while non-aciduric bacteria were eliminated, which maintained the balance of biofilm thickness. Biofilm with optimum thickness ensured oxygen transfer and H2S oxidation, avoiding the accumulation of S0. The BTF performance improved due to the enrichment of active mixotrophic SOB with high abundance under extremely acidic conditions. The mixotrophic SOB is expected to be further enriched under extremely acidic conditions by adding carbohydrates to enhance H2S removal.
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•BTF at pH 0.5–1.0 obtained an EC-H2S of 109.9 g/(m3·h) (RE = 97.0%).•Mixotrophic acidophilic SOB Alicyclobacillus (55.4%) was enriched.•High acidity eliminated non-aciduric bacteria and kept biofilm thin.•Thin biofilm ensured oxygen transfer, avoiding BTF blockage caused by S0 accumulation.•Higher EC-H2S may be obtained by adding organics to further enrich mixotrophic SOB.
Ralstonia solanacearum is an important bacterial pathogen that can infect a broad range of plants worldwide. A previous study showed that R. solanacearum could respond to exogenous organic acids or ...amino acids to modulate cell motility. However, it was unclear whether R. solanacearum uses these compounds to control infection. In this study, we found that R. solanacearum GMI1000 uses host plant metabolites to enhance the biosynthesis of virulence factors. We demonstrated that l‐glutamic acid from host plants is the key active component associated with increased extracellular polysaccharide production, cellulase activity, swimming motility, and biofilm formation in R. solanacearum GMI1000. In addition, l‐glutamic acid also promoted colonization of R. solanacearum cells in the roots and stems of tomato plants and accelerated disease incidence. Furthermore, genetic screening and biochemical analysis suggested that RS01577, a hybrid sensor histidine kinase/response regulator, is involved in l‐glutamic acid signalling in R. solanacearum. Mutations in RS01577 and exogenous addition of l‐glutamic acid to the GMI1000 wild‐type strain had overlapping effects on both the transcriptome and biological functions of R. solanacearum, including on motility, biofilm formation, and virulence. Thus, our results have established a new interaction mechanism between R. solanacearum and host plants that highlights the complexity of the virulence regulation mechanism and may provide new insight into disease control.
Ralstonia solanacearum perceives l‐glutamic acid from host plants to enhance extracellular polysaccharide production, cellulase activity, swimming motility, biofilm formation, and virulence.
Hepatocellular carcinoma (HCC) is an aggressive malignancy with increasing mortality in China. Angiogenesis is crucial for tumor formation, development and metastasis in HCC. Previous studies ...indicated that high expression levels of elongation factor 2 kinase (eEF2K), a protein kinase that negatively regulates the elongation stage of translation, were associated with poor prognosis of HCC. Here, we show that pharmacological inhibition or knockdown of eEF2K in highly metastatic liver cancer cells inhibits their colony forming and migratory capacities, as well as reducing their invasiveness. Importantly, knocking down eEF2K by lentiviral directed shRNA prevented tumor growth and angiogenesis of HCC in mice. Silencing of eEF2K in endothelial cells (HUVECs) led to a reduction in vascularization, evidenced by a decrease in capillary‐like structures in the matrigel. Notably, knocking down eEF2K reduced the expression of angiogenesis‐related growth factors in liver cancer cells and the expression of growth factor receptors on HUVECs, and thus restricted signaling crosstalk that promotes angiogenesis between HCC cells and endothelial cells. We also showed that silencing of eEF2K effectively reduced protein levels of SP1/KLF5 transcription factors and hence decreased the levels of bound SP1/KLF5 to the VEGF promoter, resulted in a decrease in VEGF mRNA expression. Knocking down eEF2K also led to a striking decrease in the phosphorylation of PI3K/Akt and STAT3, indicating inactivation of these tumorigenic pathways. Taken together, our data suggest that eEF2K contributes to angiogenesis and tumor progression in HCC via SP1/KLF5‐mediated VEGF expression, as well as the subsequent stimulation of PI3K/Akt and STAT3 signaling.
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Eukaryotic elongation factor 2 kinase (eEF2K) represses protein synthesis by preventing ribosomes from moving along the mRNA strand. Recent work has associated eEF2K with tumor cell migration and invasion. These authors show how eEF2K promotes angiogenesis and tumor progression in hepatocellular cancer (HCC). Knocking down eEF2K in metastatic liver cancer cells reduced the cells’ invasiveness. Cells without eEF2K had less SP1/KLF5 transcription factors, which reduced the amount of VEGF mRNA in the cell. The cells also showed less activity in the PI3K/Akt and STAT pathways. Reducing eEF2K expression in mice, they found, prevented HCC tumor growth and angiogenesis.
Reducing the hydrodynamic force for a cylindrical structure is extremely important in oceanic engineering applications. In this study, an auxiliary structure, shaped by two controlling parameters, is ...proposed to be placed in front of a typical circular bridge pier, desiring to mitigate the hydrodynamic loads on the pier. Two-dimensional numerical simulations are carried out through the open source CFD (computational fluid dynamics) program OpenFOAM to optimize the shape of the auxiliary structure by using a developed adaptive surrogate model, where the optimal auxiliary structure is identified by searching optimal hydrodynamic indexes, i.e., the drag and lift coefficients. The salient observations show that: (1) High efficiency is embodied in the whole optimization procedure by way of adopting the developed adaptive model; (2) The optimal auxiliary structure is featured with convex surfaces and can reduce the vortex scale and accelerate the vortex dissipation; (3) Investigation of the hydrodynamic performance proves that the optimal auxiliary structure can effectively decrease the drag and lift coefficients; and (4) The excellent performance emanating from the optimal auxiliary structure retains for a large range of the Reynolds numbers. It is hoped that the presented concept of the optimal auxiliary structure can provide guidance on mitigating the hydrodynamic loads for other oceanic engineered structures.
•A new auxiliary structure is proposed to reduce the hydrodynamic force on circular pier.•An adaptive surrogate model with a multi-point enrichment scheme is developed.•Wavelet analysis is carried out to analyze the features of the wake flows.•The optimal auxiliary structure has a weak dependency on Reynolds number.
Bone marrow-derived CD34-positive (CD34+) endothelial progenitor cells (EPCs) has unique functions in the mechanism of compensatory lung growth (CLG). The content of this study is mainly to describe ...the effect of microRNA (miR)-155 in the mechanisms of EPCs and CLG. Our study found that transfection of miR-155 mimic could promote EPC proliferation, migration and tube formation, while transfection of miR-155 inhibitor had the opposite effect. It was also found that transfection of pc-JARID2 inhibited EPC proliferation, migration and tube formation, while transfection of si-JARID2 had the opposite effect. miR-155 can target and negatively regulate JARID2 expression. Overexpression of JARID2 weakened the promoting effects of miR-155 mimic on EPC proliferation, migration, and tubular formation, while silencing JARID2 weakened the inhibitory effects of miR-155 inhibitors on EPC proliferation, migration, and tubular formation. Transplantation of EPCs transfected with miR-155 mimic into the left lung model effectively increased lung volume, total alveolar number, diaphragm surface area, and lung endothelial cell number, while transplantation of EPCs co-transfected with miR-155 mimic and pc-JARID2 reversed this phenomenon. Overall, we found that miR-155 activates CD34+ EPC by targeting negative regulation of JARID2 and promotes CLG.
Since 5-hydroxymethylfurfural (HMF) becomes a neo-forming contaminant with latent harm to human health, development of new method for highly sensitive detection of HMF is extremely desirable. Herein, ...a novel ratiometric fluorescence sensor based on strand displacement reaction and magnetic separation was designed for sensitive and selective detection of HMF with the help of MnO2 nanosheets. The aldehyde-functionalized DNA (S0–CHO) and HMF competed for binding to amino-functionalized magnetic beads (NH2-MBs). Then, S0–CHO was collected from supernatant by magnetic separation. In the presence of HMF, the obtained S0–CHO induced the formation of T-shaped DNA by strand displacement reaction (SDR), lighting the fluorescence of FAM. In the absence of HMF, no S0–CHO was present to ignite T-shaped DNA. In this situation, fluorescence of Cy5 was turned on. Thus, a ratiometric fluorescence sensor for high-sensitive detection of HMF was developed. The sensor has a wide linear range from 5 nM to 5 μM. It also exhibited high selectivity against other potential interfering substances. It has been successfully applied to analyze HMF in food samples. The method has potential to be expanded to detect other molecules containing aldehyde groups and further be applied in food safety, environment and other fields.
A ratiometric fluorescence sensor based on strand displacement reaction and magnetic separation was designed for sensitive and selective detection of HMF with the help of MnO2 nanosheets. Display omitted
•The biosensor was based on the formation of “T" shaped DNA by strand displacement reaction.•Ratio fluorescence effectively reduced the interference and improve the accuracy of HMF analysis.•The biosensor has high specificity and has been applied to detect HMF in real samples.
The present study involves diversity and biological activities of the endophytic fungal community from Distylium chinense, a rare waterlogging tolerant plant endemic to the Three Gorges Reservoir. ...This study has been conducted hypothesizing that the microbial communities in the TGR area would contribute to the host plant tolerating a range of abiotic stress such as summer flooding, infertility, drought, salinity and soil erosion etc., and they may produce new metabolites, which may possess plentiful bioactive property, especially antioxidant activity. Therefore in the current study, the antioxidant, antimicrobial and anticancer activities of 154 endophytes recovered from D. chinense have been investigated. Furthermore, the active metabolites of the most broad-spectrum bioactive strain have also been studied.
A total of 154 fungal endophytes were isolated from roots and stems. They were categorized into 30 morphotypes based on cultural characteristics and were affiliated with 27 different taxa. Among these, the most abundant fungal orders included Diaporthales (34.4%) and Botryosphaeriales (30.5%), which were predominantly represented by the species Phomopsis sp. (24.7%) and Neofusicoccum parvum (23.4%). Fermentation extracts were evaluated, screening for antioxidant, antimicrobial and anticancer activities. Among the 154 isolates tested, 99 (64.3%) displayed significant antioxidant activity, 153 (99.4%) exhibited inclusive antimicrobial activity against at least one tested microorganism and 27 (17.5%) showed exclusive anticancer activity against one or more cancer cell lines. Specifically, the crude extract of Irpex lacteus DR10-1 exhibited note-worthy bioactivities. Further chemical investigation on DR10-1 strain resulted in the isolation and identification of two known bioactive metabolites, indole-3-carboxylic acid (1) and indole-3-carboxaldehyde (2), indicating their potential roles in plant growth promotion and human medicinal value.
These results indicated that diverse endophytic fungal population inhabits D. chinense. One of the fungal isolate DR10-1 (Irpex lacteus) exhibited significant antioxidant, antimicrobial and anticancer potential. Further, its active secondary metabolites 1 and 2 also showed antioxidant, antimicrobial and anticancer potential.
Images of original pupae of Zeugodacus cucurbitae (Coquillett) were normalized, grayed, and segmented to identify male and female pupae of this species via machine vision. The image of each pupa was ...divided into 25 small areas. The differences in surface texture features in each small area within 11 days were compared. The texture characteristics of both male and female pupae were screened by combining the eclosion of both sexes of Z. cucurbitae (Coquillett). Results indicated that the pectinate setae on the abdominal backplane could be used as a basis for the identification of the male and female pupa of Z. cucurbitae (Coquillett). Moreover, machine vision correctly identified these characteristics with an accuracy of 96.0%. This study lays a foundation for the identification of male and female pupae using machine vision and also for the comprehensive control of Z. cucurbitae (Coquillett).
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•Biofilms effectively accumulate nitrite during heterotrophic nitrate reduction.•High nitrite accumulation was achieved in biofilms under varying temperatures.•Nitrite reduction rate ...was continuously suppressed even in the absence of nitrate.•Nitrite accumulation in biofilms induced in situ enrichment of anammox bacteria.
In situ enrichment of anammox bacteria in anoxic biofilms has been observed, but the specific conditions for anammox competition with denitrification for nitrite are not yet fully understood. Therefore, an anoxic sequencing batch biofilm reactor (SBBR) was used to investigate nitrite production during denitrification. In each SBBR cycle, with nearly 80% of nitrate reduced in 3 h, over 9.7 mg/L nitrite was gradually accumulated and maintained for a long time, despite temperatures gradually decreasing from 32 to 5 ℃. The long-term existence of nitrite was due to the low biofilm nitrite reduction rate (1.2 mgN gVSS−1 h−1), which was about 10-fold less than the nitrate reduction rate. Accordingly, nitrite reduction via denitrifiers was continuously suppressed, which was favorable for nitrite reduction through the anammox pathway. Indeed, anammox bacteria were successfully enriched here (Candidatus_Brocadia, 0.1%). This study confirms the potential of anoxic biofilm in enriching anammox bacteria and provides insight into understanding.
How to monitor and identify fracture initiation and propagation is a significant work for the laboratory experiment studies of hydraulic fracturing. In this paper, four main monitoring methods are ...reviewed and compared through the tri-axial fracturing experiments with natural shale outcrops, including tracer labeling, acoustic emission (AE) monitoring, computerized tomography (CT) scanning and visual fracturing method. Results show that for tracer labeling, fluorescent tracer could visually monitor the hydraulic fracture distribution morphologies, but it has a poor compatibility with slippery water. For the method of AE monitoring, dynamic three dimensional (3D) hydraulic fracture propagation process can be monitored by fixing AE sensors on specimen surfaces. However, the AE signal might display inconsistency with fracture path, which is affected by shale heterogeneity, natural fractures and bedding planes. For the method of CT scanning, many internal rock features can be well recognized, including the location of primary and activated fractures, fracture scales and the interactions between hydraulic fracture and natural fractures. However, CT scanning method cannot identify some micron-and nanoscale fractures characteristics. For the method of visual fracturing, the injected low-temperature metal can extract the fractures skeleton and measure fracture morphologies precisely, but temperature have a significant impact on experiment results. Therefore, combinations of multiple monitoring methods are recommended in laboratory experiment studies. For example, the combination of AE monitoring and CT scanning can effectively identify the propagation behavior of complex fracture network.
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