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As a folate antagonist, methotrexate (MTX) has been widely used in clinics with good effects on various tumors and inflammatory diseases. While the optimum dosage and total body clearance of MTX usually varies between individuals and even low-dose MTX has side effects, high-dose MTX may cause life-threatening side effects. Therefore, a convenient and simple method toward MTX sensing is highly demanded. Herein, we report a highly sensitive and selective method for therapeutic drug monitoring (TMD) of MTX by integrating a highly specific MTX-dependent structure-switching aptamer with a primer exchange reaction-based signal amplification technique. The detection limit is down to 1.7 nM with a linear range from 0.01 to 1 μM in buffer. More importantly, the sensing strategy can effectively detect MTX in a complex bio-environment with a linear response range from 0.05 to 2 μM and a LOD of 12.4 nM in 10% FBS and a range of 0.2 to 5 μM with a LOD of 63.73 nM in 10% whole blood. Considering the high sensitivity and selectivity and good performance in blood, the method reported herein paves a new avenue for the effective determination of MTX in clinics.

The landscapes on Earth are shaped by the interaction of tectonics and erosion processes and thus is a recorder for past tectonic and climatic histories. A recently proposed geomorphologic index for fluvial landscape, χ, can indicate the drainage divide migration from the smaller-χ-value side to the other and provide a quick estimation of the dynamic state of drainage systems. Since then, this index has been frequently used to determine divide mobility and hence landscape evolution. Some factors, however, have substantial impacts on the interpretation of the χ value, including tectonic activities, rock erodibility, and precipitation differences. Here we set a series of numerical simulations implemented on the landscape evolution model of DAC (Divide and Capture). Each simulation includes a spatial variation of a particular factor to examine the relationship between divide migration and χ values. Our numerical modelling results indicate that the migration direction is related to cross-divide contrast in erosion rate rather than χ. We take the Wula Shan horst as a natural example to demonstrate a static drainage divide but with discrepancies of cross-divide χ values in a setting of spatially asymmetric uplift. Our results suggest that a straightforward relationship between cross-divide contrasts in χ values and the drainage divide motion may not exist when spatial and temporal variations exist in the rock uplift rate, lithology, and precipitation. We emphasize that researchers should take notice of the requisite assumptions and scope of the application when using this index in landscape analysis.

Supplementary Figure S1. Western blot characterization of antibodies against BCKDH-E1 and BCKDH-pSer-E1

Supplementary Figure S2. Brain Metastatic Cells Contain High Levels of Glycogen

Breast cancer brain metastasis is resistant to therapy and a particularly poor prognostic feature in patient survival. Altered metabolism is a common feature of cancer cells, but little is known as to what metabolic changes benefit breast cancer brain metastases. We found that brain metastatic breast cancer cells evolved the ability to survive and proliferate independent of glucose due to enhanced gluconeogenesis and oxidations of glutamine and branched chain amino acids, which together sustain the nonoxidative pentose pathway for purine synthesis. Silencing expression of fructose-1,6-bisphosphatases (FBP) in brain metastatic cells reduced their viability and improved the survival of metastasis-bearing immunocompetent hosts. Clinically, we showed that brain metastases from human breast cancer patients expressed higher levels of FBP and glycogen than the corresponding primary tumors. Together, our findings identify a critical metabolic condition required to sustain brain metastasis and suggest that targeting gluconeogenesis may help eradicate this deadly feature in advanced breast cancer patients. Cancer Res; 75(3); 554–65. ©2014 AACR.

The chemical analysis and the expression patterns of related genes were determined to reveal and compare the adaptation mechanism of T. mongolica and Z. xanthoxylum to arid environments. Tetraena mongolica Maxim, the only member of the Tetraena genus in the Zygophyllaceae, is endemic to the northwest of China and is normally accompanied by another plant species in the same taxonomic family, Z. xanthoxylum (Bunge) Engl, and they play a key role in the ecology of the local environment. In order to survive in the local arid environment, many plants have developed a variety of adaptive mechanisms, including the formation of effective protective barrier, such as suberin in the stems and roots that can prevent plants from losing water and improve their adaptability to water-deficient environments. Previous studies have shown that Z. xanthoxylum had stronger drought tolerance than T. mongolica. Here, the water loss rates, the chemical composition of suberin and associated fatty acids in the periderms of stems and roots from T. mongolica and Z. xanthoxylum were determined. The expression level of genes related to suberin and associated fatty acid metabolism of the two species were also analyzed through transcriptome sequencing. The results showed that the stem and root periderms of these two species had similar chemical composition of suberin and fatty acids; however, much higher amount of suberin monomers and fatty acids were found in T. mongolica. Accordingly, transcriptome sequencing showed that more of the differentially expressed genes (DEGs) associated with suberin and associated fatty acid biosynthesis were up-regulated in the stem periderms of T. mongolica; however, minority of DEGs were up-regulated in root periderms of T. mongolica, compared with Z. xanthoxylum. This study lays an important foundation for revealing the adaptation mechanism of T. mongolica and Z. xanthoxylum to arid environments and for comparing the adaptability differences of these two species.

Herein, we report a portable point-of-care testing (POCT) device based on an aptamer-engineered extended-gate field-effect transistor (EG-FET) for therapeutic monitoring of the drug methotrexate. This method was shown to be highly sensitive, efficient, and convenient to use, features contributing to its realizing a clinical detection of drugs in blood.

Cuticular lipids, including wax and cutin, protect plants against external environmental stress. The relationship between the cuticle properties and salt tolerance is not clear. In this article, photosynthetic and physiological characteristics related to water use and cuticle permeability were assessed in the leaves of Thellungiella salsuginea under NaCl stress. The chemical composition of wax and cutin monomers, and the expression of cuticle-associated genes were also analyzed. The results showed that the net photosynthetic rate and stomatal conductance in the leaves of T. salsuginea decreased, and the water use efficiency increased with increasing NaCl concentration. Salt stress caused a significant increase in total wax, but total cutin monomers only increased under high salt. Transcriptome sequencing and lipid metabolism pathway analysis were performed on rosette leaves of T. salsuginea after 24 h of NaCl treatment. We analyzed the expression of 42 genes involved in cuticle lipid metabolism, and found that most of them exhibited higher expression levels at 0.15 mol L

Methotrexate (MTX), a folate antagonist drug, has been widely used for treating various cancers. Since high-dose MTX treatment can cause unwanted serious side effects, tracking the blood concentration of MTX is essential for safe medication. However, available methods are often complex, time-consuming, and expensive. In this study, a highly selective DNA aptamer was selected for recognizing MTX based on a capture-systematic evolution of ligands by an exponential enrichment (C-SELEX) approach. Taking advantage of our selected MTX aptamer, we further unveil a novel structure-switching fluorescent sensor for the specific and rapid monitoring of MTX with good analytical performances (i.e., a linear detection range of 0.1-2 μM with a low detection limit (LOD) of 0.03 μM in buffer and a linear detection range of 0.5-10 μM with an LOD of 0.18 μM in 50% serum). Compared with conventional methods, this assay has great potential for detecting the blood concentration of MTX in clinical use. By coupling with other sensory techniques, our presented aptamer will potentially inspire the development of various sensors toward the monitoring of MTX.

The first transcriptome analyses of Tetraena mongolica provided 224,618 Unigenes and identified the genes that were differentially expressed under salt and drought conditions, giving some insights into the unique adaptive capacity of this relic plant. Tetraena mongolica Maxim, the only member of the Tetraena genus in the Zygophyllaceae, is endemic to the northwest of China. As one of the relic shrubs of the Paleo-Mediterranean flora, T. mongolica plays a key role in preserving the local ecological environment. To investigate its good adaptability in desert, we studied the transcriptome of T. mongolica under NaCl and PEG6000 stresses. Three libraries were constructed from a mixture of seedlings and mature plants of T. mongolica, and the de novo transcriptome was sequenced using an Illumina HiSeq 4000. Approximately 218.15 million clean reads were assembled de novo into 383,612 transcripts, and 116,027 All-Unigenes were identified. By aligning All-Unigene sequences against the NR database, we found that most of the All-Unigenes had very low matches with the sequences from other plants. A total of 21,112 SSRs and 6 types of SNP variants were identified. The RNA-Seq data revealed 60 transcription factor (TF) families with 3163 genes in total. Six libraries were constructed from the separate control or stressed seedlings, and the transcriptome was sequenced using a BGISEQ-500 platform. There are 1105 and 1383 differentially expressed genes (DEGs) with 42 and 54 TFs under NaCl and PEG6000 treatment, respectively. The genes that were putatively involved in salt and osmotic stresses were searched and analyzed. Quantitative reverse transcription PCR (qRT-PCR) showed that DEG expression profiles were consistent with those from RNA-seq (RNA sequencing). Overall, this study provides new insights into the molecular mechanisms that control salt and drought stress responses in T. mongolica.

As endogenous biomolecules, guanine, guanine-based nucleosides, and nucleotides are essential for cellular DNA/RNA synthesis, energy metabolism, and signal transduction. However, these biomolecules have been found to have a cell-specific antiproliferation effect at higher concentrations, and the mechanism is unclear. In this study, we demonstrate that guanine deaminase (GDA) is a major factor in determining the cell-type selectivity to the antiproliferation effect of guanine-based biomolecules. GDA catalyzes the deamination of guanine to xanthine, which is an essential part of the guanine degradation pathway. GDA deficient cells could not efficiently remove the excess guanine-based biomolecules. These excess molecules disturb the metabolism of adenine-, cytosine-, and thymine-based nucleotides; subsequently inhibit the DNA synthesis and cell growth; and eventually result in the apoptosis/death of GDA deficient cells. The inhibition of DNA synthesis could be relieved by simultaneous addition of adenine- and cytosine-based nucleosides, and the inhibited DNA synthesis could be restarted by post addition of them, which subsequently reduces the antiproliferation effect of guanine-based biomolecules or even totally restores the cell proliferation. These results provide important information for the development of guanine-based drugs or guanine-rich oligonucleotide drugs, as well as for the safety evaluation of food with a high level of guanine-based compounds.

Ovarian cancer is regarded as the most lethal gynecologic malignancy with poor prognosis and high mortality rate. Drug-resistance was thought to be the main obstacle to improving overall survival rate of ovarian cancer. New ligands for drug-resistant ovarian cancer cells have potential for the development of diagnosis and therapy of ovarian cancer. In present work, we reported two aptamers, HF3-58 and HA5-68 generated by cell-SELEX, against a paclitaxel-resistant ovarian cancer cell line (A2780T). Both two aptamers exhibited high selectivity and strong affinity to target cells with low nanomolar dissociation constants. The binding of aptamers to target cells was independent of divalent ions, and was tolerant of incubation temperature and nucleases in serum. Molecular targets of the two aptamers were preliminarily demonstrated to be two different glycoproteins on cell surface of A2780T cells. Owing to the structure stability and high resistance to nuclease, these two aptamers had good performance in the detection of drug-resistant ovarian cancer cells in human serum.

The G-quadruplex (G4) structures of nucleic acids are considered to play an intrinsic role in gene expression. To this end, the development of new G4 ligands has attracted extensive research interests towards potential applications as G4-targeted drugs and molecular probes. To date, the majority of G4 ligands have been composed of an extended planar aromatic scaffold that interacts with the terminal G-tetrad plane via π-π interactions, and various side chains that interact with the sugar-phosphate backbone, loops or grooves of the G4 structures. The side chains act to modulate the affinity and selectivity of the G4 ligands, alongside influencing their biodistribution. Here, we present a click chemistry methodology to generate a series of squaraine-based G4 ligand derivatives based on our previously reported G4 probe (named CSTS) but with varing side chains. We find that importantly these new G4 ligand derivatives retain the G4 selectivity, optical properties and low cytotoxicity of CSTS, but exhibit different binding behaviors to G4 structures, and distinct cellular uptake efficiencies. Indeed, of these new complexes, several exhibit much higher affinity and cellular uptake than CSTS. Overall, this novel, facile and highly effective strategy has significant future potential for the high-throughput screening of G4 ligands or probes targeted towards in vivo applications.

Plant cuticle lipids form outer protective layers to resist environmental stresses, however, the relationship between cuticle properties and cold tolerance is unclear. Here, the extremophyte Thellungiella salsuginea was stressed under cold conditions (4 &deg, C) and the cuticle of rosette leaves was examined in terms of epicuticular wax crystal morphology, chemical composition, and cuticle-associated gene expression. The results show that cold induced formation of distinct lamellas within the cuticle ultrastructure. Cold stress caused 14.58% and 12.04% increases in the amount of total waxes and cutin monomer per unit of leaf area, respectively, probably associated with the increase in total fatty acids. The transcriptomic analysis was performed on rosette leaves of Thellungiella exposed to cold for 24 h. We analyzed the expression of 72 genes putatively involved in cuticle lipid metabolism, some of which were validated by qRT-PCR (quantitative reverse transcription PCR) after both 24 h and one week of cold exposure. Most cuticle-associated genes exhibited higher expression levels under cold conditions, and some key genes increased more dramatically over the one week than after just 24 h, which could be associated with increased amounts of some cuticle components. These results demonstrate that the cuticle provides some aspects of cold adaptation in T. salsuginea.

Precise doses of antibiotics are necessary to prevent bacterial drug resistance. Although fluorescent sensors are promising for quantitative analyses of antibiotics, improvements in feasibility, selectivity, and sensitivity are needed. In this study, a dual-emission fluorescence biosensor platform was developed for simple, selective, and sensitive determination of vancomycin (Van) based on a peptide conjugated with blue-emitting aggregation-induced emission luminogens (AIEgen) and aptamer-modified red-emitting gold nanoclusters (AuNCs-apt). The peptide and aptamer together recognized Van with high affinity, thus changing the fluorescence intensity at 470 nm and 650 nm, respectively. This platform displayed excellent linear correlation between the fluorescence response and a Van concentration ranging 0.01–100 μg mL−1, and the limit of detection (LOD) was 2.79 ng mL−1. In addition to the ability to accurately distinguish Van from glycopeptide antibiotics, the newly developed biosensor allowed for naked-eye detection of 1 μg mL−1 Van. These results and those of serum samples and microdialysate samples support the application of this newly developed method for Van monitoring and clinical diagnosis.

Tetraena mongolica Maxim, a relic shrub of the paleo-Mediterranean flora, is normally accompanied in the Western Ordos desert by another plant species in the same taxonomic family, Zygophyllum xanthoxylum (Bunge) Maxim, and together they play a vital role in the ecology of the local environment. Z. xanthoxylum has been identified as having stronger drought tolerance than T. mongolica. As an important water barrier, cuticles were compared between these two relatives to better reveal the mechanism of their different drought tolerance. Z. xanthoxylum possesses more flattened wax crystals, lower epidermal permeability and higher water use efficiency (WUE) than T. mongolica. The composition of cuticular lipids were analyzed, and the results showed that Z. xanthoxylum had significantly higher total amounts of both cuticular wax and cutin monomers than T. mongolica, with all wax class (especially alkanes) and cutin monomer amounts being much higher in Z. xanthoxylum. Cuticle-associated genes were analyzed by transcriptome sequencing, and the results showed that more alkane synthesis genes were up-regulated in Z. xanthoxylum. These findings provide different cuticles on these two succulent xerophytes and reveal the relationships with their different drought tolerance. This study is helpful to reveal the function of plant cuticle in adaptability to extreme environments.

The plant cuticle is a complex structure composed primarily of wax and cutin, but also contains cutan, glycerolipids, phenolics, polysaccharides and proteins. The cuticle plays an important protective role as barrier between plants and their environment. In this paper, 4-week-old leaves produced either on the rosette or on the inflorescence stem of the model extremophyte Thellungiella salsuginea were examined using scanning electron microscopy, cuticle permeability assays and chemical composition analysis. Results showed that stem leaves (SL) had more abundant cuticle lipids and lower cuticle permeability than rosette leaves (RL). SL were dominated by alkanes, especially the C29 and C31 homologs, whereas in RL the most abundant wax class was free very long-chain acids. The major cutin monomers for both leaf types were C18:2 dioic acids and 18-OH C18:2 acids. We performed Illumina high-throughput sequencing for SL and RL, and 3577 differentially expressed genes were identified. Sixty-five genes possibly involved in cuticular lipid biosynthesis, transport, or regulation was selected for further analysis. Many cuticle-associated genes exhibited differential expression levels that could be associated with compositional differences between these two leaf types. Furthermore, transcription factors and other regulatory proteins previously associated with cuticle production were expressed at higher levels in SL than in RL. The associations between gene expression and characteristics of this extremophile's leaf cuticles sheds new light on cuticle as an adaptive trait in extreme environments, and contributes new information that may guide efforts to modify crop cuticles for improved stress tolerance.

Breast cancer brain metastasis is resistant to therapy and a particularly poor prognostic feature in patient survival. Altered metabolism is a common feature of cancer cells, but little is known as to what metabolic changes benefit breast cancer brain metastases. We found that brain metastatic breast cancer cells evolved the ability to survive and proliferate independent of glucose due to enhanced gluconeogenesis and oxidations of glutamine and branched chain amino acids, which together sustain the nonoxidative pentose pathway for purine synthesis. Silencing expression of fructose-1,6-bisphosphatases (FBP) in brain metastatic cells reduced their viability and improved the survival of metastasis-bearing immunocompetent hosts. Clinically, we showed that brain metastases from human breast cancer patients expressed higher levels of FBP and glycogen than the corresponding primary tumors. Together, our findings identify a critical metabolic condition required to sustain brain metastasis and suggest that targeting gluconeogenesis may help eradicate this deadly feature in advanced breast cancer patients. Cancer Res; 75(3); 554–65. ©2014 AACR.

The cuticle plays a critical role as barrier between plant and environment. Here, cuticular wax morphology, cuticular wax and cutin monomer composition, and expression of associated genes in five above ground organs were examined in model extremophyte Thellungiella salsugineum. Alkanes, ketones, and 2-alcohols were the predominant wax constitutes in rosette leaves, inflorescence stem leaves, stems, and siliques, whereas alkanes and acids were the predominant cuticular lipids in whole flowers. Unsubstituted acids were the most abundant cutin monomers in vegetative organs, especially C18:2 dioic acids, which reached the highest levels in stems. Hydroxy fatty acids were the predominant cutin monomers in flowers, especially 16-OH C16:0 and diOH C16:0. High-throughput RNA-Seq analysis using the Hiseq4000 platform was performed on these five above organs of T. salsugineum, and the differentially expressed lipid-associated genes and their associated metabolic pathways were identified. Expression of genes associated in previous reports to cuticle production, including those having roles in cuticle lipid biosynthesis, transport, and regulation were examined. The association of cuticle lipid composition and gene expression within different organs of T. salsugineum, and potential relationships between T. salsugineum's extreme cuticle and its adaptation to extreme environments is discussed.

The effects of copper and polytetrafluoroethylene (PTFE) on thermal conductivity and tribological behavior of polyoxymethylene (POM) composites were investigated by a hot disk thermal analyzer and an M-2000 friction and abrasion testing machine. The results indicated that the incorporation of 3 wt% copper particles into POM had little effect on the thermal conductivity of POM composites, but led to the decreased friction coefficient and wear rate of composites. As the copper content was increased, the thermal conductivity increased and reached 0.477 W m−1 K−1 for POM-25% Cu composite, an increase of 35.9% compared with that of unfilled POM, while the friction coefficient and wear rate of composites also increased. The incorporation of PTFE into POM-Cu composites had a negligible effect on the thermal conductivity of composites, but helped in the formation of a continuous and uniform transfer film and resulted in the reduction in the friction coefficient and wear rate of composites. The POM-15% Cu-10% PTFE...

In this work, perfluoroalkylmethacrylate ester (PFAMAE)-grafted-linear low-density polyethylene (LLDPE) was synthesized by UV-induced surface graft polymerization. The effect of PFAMAE-grafted-LLDPE on the tribological behavior of LLDPE-filled polyoxymethylene (POM) composite was investigated using a friction and abrasion testing machine. The results showed that LLDPE-g-PFAMAE was a more effective modifier in improving tribological property of LLDPE-filled POM composite than conventional maleic anhydride-grafted-polyethylene (PE-g-MAH). POM/LLDPE composite possessed much lower friction coefficient but higher wear rate than pristine POM. The incorporation of LLDPE-g-PFAMAE into POM/LLDPE further decreased the friction coefficient, which was 45% lower than that of POM. The wear rate of POM/LLDPE/LLDPE-g-PFAMAE composite was also reduced and was lower than that of pristine POM. The primary wear mechanisms of POM/LLDPE composite with and without LLDPE-g-PFAMAE were adhesive and abrasive wear. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers

The polyoxymethylene (POM) composites with different copper contents were prepared by extrusion. The thermal conductivity and tribological behavior of POM-Cu composites with various contents of copper particles were investigated by a hot disk thermal analyzer and an M-2000 friction and abrasion testing machine, respectively. The effect of copper particles on the thermal conductivity of POM composites was negligible when copper content was below 10 wt %. As the copper content increased, the thermal conductivity of composites increased and reached 0.477 W m−1 K−1 for POM-25 wt % Cu composite, which increased by 35.9% compared with that of unfilled POM. The incorporation of copper particles into POM reduced the friction coefficient of POM composites. The wear mechanisms of POM-Cu composites were adhesive and abrasive wear. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers

Antimony doped tin oxide (ATO) nanoparticles modified poly(ethylene terephthalate) (PET) composites used for manufacturing antistatic PET fiber were synthesized by in situ polymerization. The crystallization and multiple melting behavior of the nanocomposites were systemically investigated by means of Differential Scanning Calorimeter (DSC), Fourier Transform Infrared (FTIR), X-ray Diffraction (XRD) techniques. The degree of crystallinity in nanocomposites increased with increasing ATO content. Smaller and more incomplete crystals are presented in the crystalline regions of the nanocomposites with increasing the content of ATO, which could be attributed to heterogeneous nucleation effects of ATO nanoparticles. Dynamic Mechanical Analysis (DMA) measurements showed that the storage moduli of the nanocomposites increased with increasing the content of ATO, due to formation of immobilized layer between polymer and filler. The interactions between ATO and PET molecules result in high tan δ for the PET/ATO nanocomposites. Percolation threshold of PET/ATO hybrid fibers prepared by the nanocomposites at room temperature was as low as 1.05 wt %, much lower than that of the composites filled with conventional conductive particles. Adding ATO nanoparticles obviously improves the conductivity of PET. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

The physical phenomenon of the perturbation on the water surface caused by underwater acoustic signals has been analyzed in this paper. A laser probe detection system in laboratory with a semiconductor laser to measure signal underwater from the water surface was developed. Meanwhile, the synchronous measurement utilized a -200dB standard hydrophone was also done.The signal frequencies from 200Hz to 10KHz was measured and the results have been given. The experimental results show that the system is available.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.