25 research outputs found
Data_Sheet_1_Effects of wollastonite and phosphate treatments on cadmium bioaccessibility in pak choi (Brassica rapa L. ssp. chinensis) grown in contaminated soils.docx
Cadmium (Cd) contamination of soil can strongly impact human health through the food chain due to uptake by crop plants. Inorganic immobilizing agents such as silicates and phosphates have been shown to effectively reduce Cd transfer from the soil to cereal crops. However, the effects of such agents on total Cd and its bioaccessibility in leafy vegetables are not yet known. Pak choi (Brassica rapa L. ssp. chinensis) was here selected as a representative leafy vegetable to be tested in pots to reveal the effects of silicate–phosphate amendments on soil Cd chemical fractions, total plant Cd levels, and plant bioaccessibility. The collected Cd contaminated soil was mixed with control soil at 1:0, 1:1, 1:4, 0:1 with a view to Cd high/moderate/mild/control soil samples. Three heavy metal-immobilizing agents: wollastonite (W), potassium tripolyphosphate (KTPP), and sodium hexametaphosphate (SHMP) were added to the soil in order to get four different treatment groups, i.e., control (CK), application of wollastonite alone (W), wollastonite co-applied with KTPP (WKTPP), application of wollastonite co-applied with SHMP (WSHMP) for remediation of soils with different levels of Cd contamination. All three treatments increased the effective bio-Cd concentration in the soils with varying levels of contamination, except for W under moderate and heavy Cd contamination. The total Cd concentration in pak choi plants grown in mildly Cd-contaminated soil was elevated by 86.2% after WKTPP treatment compared to the control treatment could function as a phytoremediation aid for mildly Cd-contaminated soil. Using an in vitro digestion method (physiologically based extraction test) combined with transmission electron microscopy, silicate and phosphorus agents were found to reduce the bioaccessibility of Cd in pak choi by up to 66.13% with WSHMP treatment. Application of silicate alone reduced soil bio-Cd concentration through the formation of insoluble complexes and silanol groups with Cd, but the addition of phosphate may have facilitated Cd translocation into pak choi by first co-precipitating with Ca in wollastonite while simultaneously altering soil pH. Meanwhile, wollastonite and phosphate treatments may cause Cd to be firmly enclosed in the cell wall in an insoluble form, reducing its translocation to edible parts and decreasing the bioaccessibility of Cd in pak choi. This study contributes to the mitigation of Cd bioaccessibility in pak choi by reducing soil Cd concentration through in situ remediation and will help us to extend the effects of wollastonite and phosphate on Cd bioaccessibility to other common vegetables. Therefore, this study thus reveals effective strategies for the remediation of soil Cd and the reduction of Cd bioaccessibility in crops based on two indicators: total Cd and Cd bioaccessibility. Our findings contribute to the development of methods for safer cultivation of commonly consumed leafy vegetables and for soil remediation.</p
Modulating the Electrochemical Performances of Layered Cathode Materials for Sodium Ion Batteries through Tuning Coulombic Repulsion between Negatively Charged TMO<sub>2</sub> Slabs
Exploiting
advanced layered transition metal oxide cathode materials
is of great importance to rechargeable sodium batteries. Layered oxides
are composed of negatively charged TMO<sub>2</sub> slabs (TM = transition
metal) separated by Na<sup>+</sup> diffusion layers. Herein, we propose
a novel insight, for the first time, to control the electrochemical
properties by tuning Coulombic repulsion between negatively charged
TMO<sub>2</sub> slabs. Coulombic repulsion can finely tailor the <i>d</i>-spacing of Na ion layers and material structural stability,
which can be achieved by employing Na<sup>+</sup> cations to serve
as effective shielding layers between TMO<sub>2</sub> layers. A series
of O3-type Na<sub><i>x</i></sub>Mn<sub>1/3</sub>Fe<sub>1/3</sub>Cu<sub>1/6</sub>Mg<sub>1/6</sub>O<sub>2</sub> (<i>x</i> = 1.0, 0.9, 0.8, and 0.7) have been prepared, and Na<sub>0.7</sub>Mn<sub>1/3</sub>Fe<sub>1/3</sub>Cu<sub>1/6</sub>Mg<sub>1/6</sub>O<sub>2</sub> shows the largest Coulombic repulsion between TMO<sub>2</sub> layers, the largest space for Na ion diffusion, the best structural
stability, and also the longest Na–O chemical bond with weaker
Coulombic attraction, thus leading to the best electrochemical performance.
Meanwhile, the thermal stability depends on the Na concentration in
pristine materials. Ex situ X-ray absorption (XAS) analysis indicates
that Mn, Fe, and Cu ions are all electrochemically active components
during insertion and extraction of sodium ion. This study enables
some new insights to promote the development of advanced layered Na<sub><i>x</i></sub>TMO<sub>2</sub> materials for rechargeable
sodium batteries in the future
Brevilin A, a Novel Natural Product, Inhibits Janus Kinase Activity and Blocks STAT3 Signaling in Cancer Cells
<div><p>Signal abnormalities in human cells usually cause unexpected consequences for individual health. We focus on these kinds of events involved in JAK-STAT signal pathways, especially the ones triggered by aberrant activated STAT3, an oncoprotein which participates in essential processes of cell survival, growth and proliferation in many types of tumors, as well as immune diseases. By establishing a STAT3 signal based high-throughput drug screening system in human lung cancer A549 cells, we have screened a library from natural products which contained purified compounds from medicinal herbs. One compound, named Brevilin A, exhibited both strong STAT3 signal inhibition and STAT3 signal dependent cell growth inhibition. Further investigations revealed that Brevilin A not only inhibits STAT3 signaling but also STAT1 signaling for cytokines induced phosphorylation of STAT3 and STAT1 as well as the expression of their target genes. In addition, we found Brevilin A could attenuate the JAKs activity by blocking the JAKs tyrosine kinase domain JH1. The levels of cytokine induced phosphorylation of STATs and other substrates were dramatically reduced by treatment of Brevilin A. The roles of Brevilin A targeting on JAKs activity indicate that Brevilin A may not only be used as a STAT3 inhibitor but also a compound blocking other JAK-STAT hyperactivation. Thus, these findings provided a strong impetus for the development of selective JAK-STAT inhibitors and therapeutic drugs in order to improve survival of patients with hyperactivated JAKs and STATs.</p></div
Monolayer Phosphorene–Metal Contacts
Recently, phosphorene electronic
and optoelectronic prototype devices
have been fabricated with various metal electrodes. We systematically
explore for the first time the contact properties of monolayer (ML)
phosphorene with a series of commonly used metals in a transistor
by using both ab initio electronic structure calculations and more
reliable quantum transport simulations. ML phosphorene undergoes a
metallization under the checked metals, and the metallized ML phosphorenes
have an unnegligible coupling with channel ML phosphorene. ML phosphorene
forms an <i>n-</i>type Schottky contact with Au, Cu, Cr,
Al, and Ag electrodes and a <i>p-</i>type Schottky contact
with Ti, Ni, and Pd electrodes upon inclusion of such a coupling.
The calculated Schottky barrier heights are in good agreement with
the available experimental data with Ni and Ti as electrodes. Our
findings not only provide an insight into the ML phosphorene–metal
interfaces but also help in ML phosphorene based device design
Forward Genetic Screening for Regulators Involved in Cholesterol Synthesis Using Validation-Based Insertional Mutagenesis
<div><p>Somatic cell genetics is a powerful approach for unraveling the regulatory mechanism of cholesterol metabolism. However, it is difficult to identify the mutant gene(s) due to cells are usually mutagenized chemically or physically. To identify important genes controlling cholesterol biosynthesis, an unbiased forward genetics approach named validation-based insertional mutagenesis (VBIM) system was used to isolate and characterize the 25-hydroxycholesterol (25-HC)-resistant and SR-12813-resisitant mutants. Here we report that five mutant cell lines were isolated. Among which, four sterol-resistant mutants either contain a truncated NH<sub>2</sub>-terminal domain of sterol regulatory element-binding protein (SREBP)-2 terminating at amino acids (aa) 400, or harbor an overexpressed SREBP cleavage-activating protein (SCAP). Besides, one SR-12813 resistant mutant was identified to contain a truncated COOH-terminal catalytic domain of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG-CoA reductase). This study demonstrates that the VBIM system can be a powerful tool to screen novel regulatory genes in cholesterol biosynthesis.</p></div
DataSheet_1_Integrated transcriptomic and metabolomic analysis reveals the metabolic programming of GM-CSF- and M-CSF- differentiated mouse macrophages.docx
Macrophages play a critical role in the inflammatory response and tumor development. Macrophages are primarily divided into pro-inflammatory M1-like and anti-inflammatory M2-like macrophages based on their activation status and functions. In vitro macrophage models could be derived from mouse bone marrow cells stimulated with two types of differentiation factors: GM-CSF (GM-BMDMs) and M-CSF (M-BMDMs), to represent M1- and M2-like macrophages, respectively. Since macrophage differentiation requires coordinated metabolic reprogramming and transcriptional rewiring in order to fulfill their distinct roles, we combined both transcriptome and metabolome analysis, coupled with experimental validation, to gain insight into the metabolic status of GM- and M-BMDMs. The data revealed higher levels of the tricarboxylic acid cycle (TCA cycle), oxidative phosphorylation (OXPHOS), fatty acid oxidation (FAO), and urea and ornithine production from arginine in GM-BMDMs, and a preference for glycolysis, fatty acid storage, bile acid metabolism, and citrulline and nitric oxide (NO) production from arginine in M-BMDMs. Correlation analysis with the proteomic data showed high consistency in the mRNA and protein levels of metabolic genes. Similar results were also obtained when compared to RNA-seq data of human monocyte derived macrophages from the GEO database. Furthermore, canonical macrophage functions such as inflammatory response and phagocytosis were tightly associated with the representative metabolic pathways. In the current study, we identified the core metabolites, metabolic genes, and functional terms of the two distinct mouse macrophage populations. We also distinguished the metabolic influences of the differentiation factors GM-CSF and M-CSF, and wish to provide valuable information for in vitro macrophage studies.</p
The SR-12813-resistant mutant SL-5 produced a truncated COOH-terminal catalytic domain of HMG-CoA reductase.
<p><b>A.</b> Growth pattern of HeLa, SL-5 and its Cre recombinase treatment counterpart (SL-5+Cre). On day 0, the cells were set up in medium B with 10% FBS at 1×10<sup>4</sup> per well in 6-well plate. On day 1, the cells were changed to medium B with 10% LPDS plus 12 µM SR-12813. The cells were refed every 3 days with fresh medium with SR-12813. On Day 14, the cells were washed, fixed and stained as descripted in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0112632#pone-0112632-g002" target="_blank">Fig. 2A</a>. <b>B.</b> The wild type HeLa cells and SR-12813-resistant cell line SL-5 were set up at 4×10<sup>5</sup> per 60 mm dish in medium B supplemented with 10% FBS on day 0. Next day, the cells were changed to medium B containing 10% LPDS, 1 µM lovastatin and 10 µM mevalonate and incubated for 16 hr. On day 3, the cells were switched to medium B containing 10% LPDS, 1 µM lovastatin and 10 µM mevalonate in the absence (–) or presence of 25-HC or different concentration of SR-12813 plus 10 mM mevalonate as indicated for 5 hr, then the cells were harvested as described in “<b>Materials and methods</b>”. The aliquots were subjected to SDS-PAGE and immunoblot analysis. <b>C.</b> The total RNA was isolated and reverse-transcribed into cDNA as described in “<b>Materials and methods</b>” from the HeLa, SL-5 and SL-5+Cre cells. The aliquots of cDNA were subject to PCR analysis with the primers as indicated. The PCR products were analyzed by 1% agarose and purified for sequencing. <b>D.</b> Domain structure of <i>HMG-CoA reductase</i> gene and illustration of the insertion site of VBIM virus. The virus inserted into the 10<sup>th</sup> intron of <i>HMG-CoA reductase</i> gene,and the CMV promoter drove transcription of downstream sequences which encoded a truncated COOH-terminal domain of HMG-CoA reductase.</p
Mutant cell lines with defects in SREBP processing and HMG-CoA reductase degradation<sup>*</sup>.
<p>*This table is modified from TABLE II of reference <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0112632#pone.0112632-Goldstein1" target="_blank">[15]</a>.</p><p>Mutant cell lines with defects in SREBP processing and HMG-CoA reductase degradation<sup><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0112632#nt101" target="_blank">*</a></sup>.</p
The growth patterns of CHO-7 cells in different selection regents and screen strategy.
<p><b>A.</b> On day 0, the CHO-7 cells or HeLa cells were set up at 1×10<sup>4</sup> per 35 mm dish in medium A contains 5% FBS or medium B containing 10% FBS, respectively. On day 1, the cells were refed with medium A containing 5% LPDS (for CHO-7 cells) or medium B with 10% LPDS (for HeLa cells) with indicated concentration of 25-HC or SR-12813 respectively in the absence (–) or presence (+) of 5 µg/ml cholesterol. The medium were changed every 2 days. On day 14, the cells were washed once with PBS, fixed with 95% ethanol for 20 min and stained with 0.5% crystal violet for 1 hr at room temperature. <b>B.</b> The structure of provirus integrating into genome and the mutagenesis type of VBIM virus. LTR, long terminal repeats; CMV, cytomegalovirus promoter; GFP, green fluorescent protein; IRES, internal ribosome entry site; SD, splice donor site; LoxP, Cre-mediated recombination site. <b>C.</b> The forward genetic screen strategy. Cell pools were conducted with VBIM virus with MOI≈0.3. The mutagenized cells were selected with 25-HC or SR-12813. The survival clones were isolated, expanded and validated with Cre recombinase.</p
Monolayer Bismuthene-Metal Contacts: A Theoretical Study
Bismuthene, a bismuth
analogue of graphene, has a moderate band
gap, has a high carrier mobility, has a topological nontriviality,
has a high stability at room temperature, has an easy transferability,
and is very attractive for electronics, optronics, and spintronics.
The electrical contact plays a critical role in an actual device.
The interfacial properties of monolayer (ML) bismuthene in contact
with the metal electrodes spanning a wide work function range in a
field-effect transistor configuration are systematically studied for
the first time by using both first-principles electronic structure
calculations and quantum transport simulations. The ML bismuthene
always undergoes metallization upon contact with the six metal electrodes
owing to a strong interaction. According to the quantum transport
simulations, apparent metal-induced gap states (MIGSs) formed in the
semiconductor–metal interface give rise to a strong Fermi-level
pinning. As a result, the ML bismuthene forms an n-type Schottky contact
with Ir/Ag/Ti electrodes with electron Schottky barrier heights (SBHs)
of 0.17, 0.22, and 0.25 eV, respectively, and a p-type Schottky contact
with Pt/Al/Au electrodes with hole SBHs of 0.09, 0.16, and 0.38 eV,
respectively. The effective channel length of the ML bismuthene transistors
is also significantly reduced by the MIGSs. However, the MIGSs are
eliminated and the effective channel length is increased when ML graphene
is used as an electrode, accompanied by a small hole SBH of 0.06 eV
(quasi-Ohmic contact). Hence, an insight is provided into the interfacial
properties of the ML bismuthene–metal composite systems and
a guidance is provided for the choice of metal electrodes in ML bismuthene
devices