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Find video protocols related to scientific articles indexed in Pubmed.
TNFR1 mediates TNF-?-induced tumour lymphangiogenesis and metastasis by modulating VEGF-C-VEGFR3 signalling.
Nat Commun
PUBLISHED: 08-07-2014
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Inflammation and lymphangiogenesis are two cohesively coupled processes that promote tumour growth and invasion. Here we report that TNF-? markedly promotes tumour lymphangiogenesis and lymphatic metastasis. The TNF-?-TNFR1 signalling pathway directly stimulates lymphatic endothelial cell activity through a VEGFR3-independent mechanism. However, VEGFR3-induced lymphatic endothelial cell tips are a prerequisite for lymphatic vessel growth in vivo, and a VEGFR3 blockade completely ablates TNF-?-induced lymphangiogenesis. Moreover, TNF-?-TNFR1-activated inflammatory macrophages produce high levels of VEGF-C to coordinately activate VEGFR3. Genetic deletion of TNFR1 (Tnfr1(-/-)) in mice or depletion of tumour-associated macrophages (TAMs) virtually eliminates TNF-?-induced lymphangiogenesis and lymphatic metastasis. Gain-of-function experiments show that reconstitution of Tnfr1(+/+) macrophages in Tnfr1(-/-) mice largely restores tumour lymphangiogenesis and lymphatic metastasis. These findings shed mechanistic light on the intimate interplay between inflammation and lymphangiogenesis in cancer metastasis, and propose therapeutic intervention of lymphatic metastasis by targeting the TNF-?-TNFR1 pathway.
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Intracellular Thiols and Photo-Illumination Sequentially Activate Doubly Locked Molecular Probes for Long-Term Cell Highlighting and Tracking with Precise Spatial Accuracy.
Chemistry
PUBLISHED: 06-11-2014
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A novel photoconvertible fluorescent probe, which can be activated by intracellular thiols, has been synthesized. Such a molecular probe comprises three parts: a 7-aminocoumarin phototrigger, a thiol-removable energy acceptor, and a caged fluorescein scaffold with intracellular thiols reactivity as the fluorescent reporter. Extracellularly, the energy acceptor blocks the emission of the coumarin that regulates the photocleavage and photoactivation of the fluorescein. Intracelluarly, the high concentration of thiols releases the energy acceptor, thus activating the S1 state of the phototrigger, which emits coumarin blue fluorescence for pre-visualization and liberates the caged green-fluorescent fluorescein to highlight the specific cell upon illumination. Compared to traditional photoactivated organic dyes, the intracellular thiols activated probe requires double activations: one by intracellular thiols and the other by light activation. The dual activations restrict fluorescence precisely inside live cells and at the particular spatial region of light activation, thus a probe with precise spatial accuracy in live cells.
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Vesicular self-assembly of colloidal amphiphiles in microfluidics.
ACS Appl Mater Interfaces
PUBLISHED: 09-23-2013
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Hydrodynamic flow in a microfluidic (MF) device offers a high-throughput platform for the continuous and controllable self-assembly of amphiphiles. However, the role of hydrodynamics on the assembly of colloidal amphiphiles (CAMs) is still not well understood. This Article reports a systematic study of the assembly of CAMs, which consist of Au nanoparticles (AuNPs) grafted with amphiphilic block copolymers, into vesicles with a monolayer of CAMs in the membranes using laminar flows in MF flow-focusing devices. Our experimental and simulation studies indicate that the transverse diffusion of solvents and colloids across the boundary of neighboring lamellar flows plays a critical role in the assembly of CAMs into vesicles. The dimension of the vesicles can be controlled in the range of 100-600 nm by tuning the hydrodynamic conditions of the flows. In addition, the diffusion coefficient of CAMs was also critical for their assembly. Under the same flow conditions, larger CAMs generated larger assemblies as a result of the reduced diffusion rate of large amphiphiles. This work could provide fundamental guidance for the preparation of nanoparticle vesicles with applications in bioimaging, drug delivery, and nano- and microreactors.
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Vascular endothelial growth factor-dependent spatiotemporal dual roles of placental growth factor in modulation of angiogenesis and tumor growth.
Proc. Natl. Acad. Sci. U.S.A.
PUBLISHED: 08-05-2013
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Placental growth factor (PlGF) remodels tumor vasculatures toward a normalized phenotype, which affects tumor growth, invasion and drug responses. However, the coordinative and spatiotemporal relation between PlGF and VEGF in modulation of tumor angiogenesis and vascular remodeling is less understood. Here we report that PlGF positively and negatively modulate tumor growth, angiogenesis, and vascular remodeling through a VEGF-dependent mechanism. In two independent tumor models, we show that PlGF inhibited tumor growth and angiogenesis and displayed a marked vascular remodeling effect, leading to normalized microvessels with infrequent vascular branches and increased perivascular cell coverage. Surprisingly, elimination of VEGF gene (i.e., VEGF-null) in PlGF-expressing tumors resulted in (i) accelerated tumor growth rates and angiogenesis and (ii) complete attenuation of PlGF-induced vascular normalization. Thus, PlGF positively and negatively modulates tumor growth, angiogenesis, and vascular remodeling through VEGF-dependent spatiotemporal mechanisms. Our data uncover molecular mechanisms underlying the complex interplay between PlGF and VEGF in modulation of tumor growth and angiogenesis, and have conceptual implication for antiangiogenic cancer therapy.
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Anti-VEGF- and anti-VEGF receptor-induced vascular alteration in mouse healthy tissues.
Proc. Natl. Acad. Sci. U.S.A.
PUBLISHED: 07-01-2013
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Systemic therapy with anti-VEGF drugs such as bevacizumab is widely used for treatment of human patients with various solid tumors. However, systemic impacts of such drugs in host healthy vasculatures remain poorly understood. Here, we show that, in mice, systemic delivery of an anti-VEGF or an anti-VEGF receptor (VEGFR)-2 neutralizing antibody caused global vascular regression. Among all examined tissues, vasculatures in endocrine glands, intestinal villi, and uterus are the most affected in response to VEGF or VEGFR-2 blockades. Thyroid vascular fenestrations were virtually completely blocked by VEGF blockade, leading to marked accumulation of intraendothelial caveolae vesicles. VEGF blockade markedly increased thyroid endothelial cell apoptosis, and withdrawal of anti-VEGF resulted in full recovery of vascular density and architecture after 14 d. Prolonged anti-VEGF treatment resulted in a significant decrease of the circulating level of the predominant thyroid hormone free thyroxine, but not the minimal isoform of triiodothyronine, suggesting that chronic anti-VEGF treatment impairs thyroid functions. Conversely, VEGFR-1-specific blockade produced virtually no obvious phenotypes. These findings provide structural and functional bases of anti-VEGF-specific drug-induced side effects in relation to vascular changes in healthy tissues. Understanding anti-VEGF drug-induced vascular alterations in healthy tissues is crucial to minimize and even to avoid adverse effects produced by currently used anti-VEGF-specific drugs.
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Molecular and functional characterization of the first tick CAP2b (periviscerokinin) receptor from Rhipicephalus (Boophilus) microplus (Acari: Ixodidae).
Gen. Comp. Endocrinol.
PUBLISHED: 03-20-2013
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The cDNA of the receptor for CAP2b/periviscerokinin (PVK) neuropeptides, designated Rhimi-CAP2b-R, was cloned from synganglia of tick Rhipicephalus (Boophilus) microplus. This receptor is the ortholog of the insect CAP2b/PVK receptor, as concluded from analyses of the predicted protein sequence, phylogenetics and functional expression. Expression analyses of synganglion, salivary gland, Malpighian tubule, and ovary revealed Rhimi-CAP2b-R transcripts. The expression in mammalian cells of the open reading frame of Rhimi-CAP2b-R cDNA fused with a hemagglutinin tag at the receptor N-terminus was confirmed by immunocytochemistry. In a calcium bioluminescence assay the recombinant receptor was activated by the tick Ixodes scapularis CAP2b/PVK and a PVK analog with EC50s of 64nM and 249nM, respectively. Tick pyrokinins were not active. This is the first report on the functional characterization of the CAP2b/PVK receptor from any tick species which will now permit the discovery of the physiological roles of these neuropeptides in ticks, as neurohormones, neuromodulators and/or neurotransmitters.
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Tumour PDGF-BB expression levels determine dual effects of anti-PDGF drugs on vascular remodelling and metastasis.
Nat Commun
PUBLISHED: 02-20-2013
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Anti-platelet-derived growth factor (PDGF) drugs are routinely used in front-line therapy for the treatment of various cancers, but the molecular mechanism underlying their dose-dependent impact on vascular remodelling remains poorly understood. Here we show that anti-PDGF drugs significantly inhibit tumour growth and metastasis in high PDGF-BB-producing tumours by preventing pericyte loss and vascular permeability, whereas they promote tumour cell dissemination and metastasis in PDGF-BB-low-producing or PDGF-BB-negative tumours by ablating pericytes from tumour vessels. We show that this opposing effect is due to PDGF-? signalling in pericytes. Persistent exposure of pericytes to PDGF-BB markedly downregulates PDGF-? and inactivation of the PDGF-? signalling decreases integrin ?1?1 levels, which impairs pericyte adhesion to extracellular matrix components in blood vessels. Our data suggest that tumour PDGF-BB levels may serve as a biomarker for selection of tumour-bearing hosts for anti-PDGF therapy and unsupervised use of anti-PDGF drugs could potentially promote tumour invasion and metastasis.
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Highly discriminating photorelease of anticancer drugs based on hypoxia activatable phototrigger conjugated chitosan nanoparticles.
Adv. Mater. Weinheim
PUBLISHED: 02-07-2013
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An ultimately selective photorelease system of chitosan-nanoparticles is constructed. Only under unique aspects of tumor-hypoxia physiological conditions, the preliminary locked phototrigger is unlocked by biological reduction to enable the release of the caged drug either by visible light or two-photon near-IR (NIR) excitation. This approach provides a highly discriminating photorelease of anticancer drug to hypoxic tumor cells, but not to healthy normal cells.
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Occurrence and larval movement of Diatraea saccharalis (Lepidoptera: Crambidae) in seed mixes of non-Bt and Bt pyramid corn.
Pest Manag. Sci.
PUBLISHED: 01-03-2013
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Larval movement of target pest populations among Bt and non-Bt plants is a major concern in the use of a seed mixture refuge strategy for Bt resistance management. In this study, occurrence and larval movement of the sugarcane borer, Diatraea saccharalis (F.), were evaluated in four planting patterns of non-Bt and Bt plants containing Genuity® SmartStax(TM) traits in 2009-2011. The four planting patterns were: (1) a pure stand of 27 Bt plants; (2) one non-Bt plant in the center, surrounded by 26 Bt plants; (3) a pure stand of 27 non-Bt plants; (4) one Bt plant in the center, surrounded by 26 non-Bt plants. Studies were conducted under four conditions: (1) open field with natural infestation; (2) greenhouse with artificial infestations; open field with artificial infestations (3) on the center plants only and (4) on every plant. The major objective of this study was to determine whether refuge plants in a seed mixture strategy could provide a comparable refuge population of D. saccharalis to a structured refuge planting.
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PDGF-BB modulates hematopoiesis and tumor angiogenesis by inducing erythropoietin production in stromal cells.
Nat. Med.
PUBLISHED: 09-12-2011
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The platelet-derived growth factor (PDGF) signaling system contributes to tumor angiogenesis and vascular remodeling. Here we show in mouse tumor models that PDGF-BB induces erythropoietin (EPO) mRNA and protein expression by targeting stromal and perivascular cells that express PDGF receptor-? (PDGFR-?). Tumor-derived PDGF-BB promoted tumor growth, angiogenesis and extramedullary hematopoiesis at least in part through modulation of EPO expression. Moreover, adenoviral delivery of PDGF-BB to tumor-free mice increased both EPO production and erythropoiesis, as well as protecting from irradiation-induced anemia. At the molecular level, we show that the PDGF-BB-PDGFR-b? signaling system activates the EPO promoter, acting in part through transcriptional regulation by the transcription factor Atf3, possibly through its association with two additional transcription factors, c-Jun and Sp1. Our findings suggest that PDGF-BB-induced EPO promotes tumor growth through two mechanisms: first, paracrine stimulation of tumor angiogenesis by direct induction of endothelial cell proliferation, migration, sprouting and tube formation, and second, endocrine stimulation of extramedullary hematopoiesis leading to increased oxygen perfusion and protection against tumor-associated anemia.
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Microbial removal of NOX at high temperature by a novel aerobic strain Chelatococcus daeguensis TAD1 in a biotrickling filter.
J. Hazard. Mater.
PUBLISHED: 08-22-2011
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The removal of NO(X) at high temperature by Chelatococcus daeguensis TAD1 in a biotrickling filter was studied. Media components of the recycling liquid were screened using Plackett-Burman design and then were optimized using response surface methodology, which enhanced the efficiency of nitrate removal by TAD1. The optimal medium was used to perform long-term experiments of NO(X) removal in a biotrickling filter under high concentrations of O(2) and NO in simulated flue gas. Results showed that the biotrickling filter was able to consistently remove 80.2-92.3% NO(X) when the inlet NO concentration was 600ppm under the conditions of oxygen concentration ranging between 2% and 20% and empty bed residence time (EBRT) being 112.5s. Analyses by polymerase chain reaction and denaturing gradient gel electrophoresis (PCR-DGGE) indicated that TAD1 was always predominant in the biofilm under a flue gas environment. Overall, the present study demonstrated that utilizing a biotrickling filter inoculated with the aerobic denitrifier TAD1 to remove NO(X) at high temperature was practically feasible.
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Down regulation of a gene for cadherin, but not alkaline phosphatase, associated with Cry1Ab resistance in the sugarcane borer Diatraea saccharalis.
PLoS ONE
PUBLISHED: 06-24-2011
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The sugarcane borer, Diatraea saccharalis, is a major target pest of transgenic corn expressing Bacillus thuringiensis (Bt) proteins (i.e., Cry1Ab) in South America and the mid-southern region of the United States. Evolution of insecticide resistance in such target pests is a major threat to the durability of transgenic Bt crops. Understanding the pests resistance mechanisms will facilitate development of effective strategies for delaying or countering resistance. Alterations in expression of cadherin- and alkaline phosphatase (ALP) have been associated with Bt resistance in several species of pest insects. In this study, neither the activity nor gene regulation of ALP was associated with Cry1Ab resistance in D. saccharalis. Total ALP enzymatic activity was similar between Cry1Ab-susceptible (Cry1Ab-SS) and -resistant (Cry1Ab-RR) strains of D. saccharalis. In addition, expression levels of three ALP genes were also similar between Cry1Ab-SS and -RR, and cDNA sequences did not differ between susceptible and resistant larvae. In contrast, altered expression of a midgut cadherin (DsCAD1) was associated with the Cry1Ab resistance. Whereas cDNA sequences of DsCAD1 were identical between the two strains, the transcript abundance of DsCAD1 was significantly lower in Cry1Ab-RR. To verify the involvement of DsCAD1 in susceptibility to Cry1Ab, RNA interference (RNAi) was employed to knock-down DsCAD1 expression in the susceptible larvae. Down-regulation of DsCAD1 expression by RNAi was functionally correlated with a decrease in Cry1Ab susceptibility. These results suggest that down-regulation of DsCAD1 is associated with resistance to Cry1Ab in D. saccharalis.
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Mouse corneal lymphangiogenesis model.
Nat Protoc
PUBLISHED: 05-19-2011
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This protocol describes a powerful in vivo method to quantitatively study the formation of new lymphatic vessels in the avascular cornea without interference of pre-existing lymphatics. Implantation of 100 ng of lymphangiogenic factors such as vascular endothelial growth factor (VEGF)-A, VEGF-C or fibroblast growth factor-2, together with slow-release polymers, into a surgically created micropocket in the mouse cornea elicits a robust lymphangiogenic response. Newly formed lymphatic vessels are detected by immunohistochemical staining of the flattened corneal tissue with lymphatic endothelial-specific markers such as lymphatic vessel endothelial hyaluronan receptor-1; less-specific markers such as vascular endothelial growth factor receptor 3 may also be used. Lymphatic vessel growth in relation to hemangiogenesis can be readily detected starting at day 5 or 6 after pellet implantation and persists for ?14 d. This protocol offers a unique opportunity to study the mechanisms underlying lymphatic vessel formation, remodeling and function.
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Crosstalk between Raf/MEK/ERK and PI3K/AKT in suppression of Bax conformational change by Grp75 under glucose deprivation conditions.
J. Mol. Biol.
PUBLISHED: 04-13-2011
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During glucose deprivation (GD)-induced cellular stress, the molecular chaperone glucose-regulated protein 75 (Grp75)/Mortalin/PBP74/mtHSP70 (hereafter termed "Grp75") plays an important role in the suppression of apoptosis by inhibiting the Bax conformational change that delays the release of cytochrome c. The molecular pathways by which it carries out these functions are still unclear. We hypothesize that the anti-apoptotic effect by the overexpression of Grp75 was through the signal of AKT activated by classic phosphoinositide 3-kinase (PI3K) and also involved PI3K-independent pathways. Using the PC12 cell GD model, we demonstrated a novel mechanism of Grp75 activating AKT, which may be PI3K independent and associated with Raf/MEK (mitogen-activated protein kinase/ERK kinase)/ERK signaling. The PI3K inhibitor LY294002 did not influence the activation of AKT by the Grp75 overexpression under GD; however, the MEK inhibitor U0126 dramatically inhibited AKT phosphorylation in the same assay. In addition to the PI3K/AKT signal pathway, Grp75 overexpression also inhibited the Bax conformational change through the Raf/MEK/ERK signal pathway. In conclusion, Grp75 overexpression in activating AKT can be PI3K independent and associated with Raf/MEK/ERK signaling under GD. At the same time, PI3K may also crosstalk with Raf-1, in which the prosurvival signal of PI3K maintains the expression of Raf-1. The activated AKT and extracellular signal-regulated protein kinases 1 and 2 by Grp75 inhibited the Bax conformational change and subsequent apoptosis.
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F2 screening for resistance to pyramided Bacillus thuringiensis maize in Louisiana and Mississippi populations of Diatraea saccharalis (Lepidoptera: Crambidae).
Pest Manag. Sci.
PUBLISHED: 03-01-2011
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In the mid-southern region of the United States, sugarcane borer, Diatraea saccharalis (F.), is a major target pest of transgenic maize expressing Bacillus thuringiensis (Bt) proteins. Novel transgenic maize technologies containing two or more pyramided Bt genes for controlling lepidopteran pests have recently become commercially available. Insect resistance management (IRM) is an important issue in the sustainable use of Bt crop technologies. The objective of this study was to determine the frequency of resistance alleles in field populations of D. saccharalis to the new pyramided Bt maize technologies.
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Molecular characterization and RNA interference of three midgut aminopeptidase N isozymes from Bacillus thuringiensis-susceptible and -resistant strains of sugarcane borer, Diatraea saccharalis.
Insect Biochem. Mol. Biol.
PUBLISHED: 04-07-2010
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Aminopeptidase N (APN) proteins located at the midgut epithelium of some lepidopteran species have been implicated as receptors for insecticidal proteins from Bacillus thuringiensis. cDNAs of three APN isoforms, DsAPN1, DsAPN2, and DsAPN3, from Cry1Ab-susceptible (Cry1Ab-SS) and -resistant (Cry1Ab-RR) strains of the sugarcane borer, Diatraea saccharalis (F.) (Lepidoptera: Crambidae), were identified and sequenced using reverse transcriptase polymerase chain reaction (RT-PCR) and 5 rapid amplification of cDNA end (5 RACE). The characteristic APN sequence features were derived from deduced amino acid sequences of the cloned cDNAs. cDNA sequences of the three APN genes were identical between the Cry1Ab-SS and -RR strains. However, total APN proteolytic activity and gene expression of the three APNs from Cry1Ab-RR larvae were significantly lower than those of the Cry1Ab-SS strain. RNA interference (RNAi) was employed using an oral droplet feeding technique for the three APNs of the Cry1Ab-SS strain. Down-regulating expressions of the three APN genes by RNAi were corresponding to the reductions in the specific APN activity. In addition, silencing of all three APNs in D. saccharalis in vivo by RNAi resulted in a decrease in Cry1Ab susceptibility. Our results showed that reduction in expression of the three APNs is functionally associated with the Cry1Ab resistance in D. saccharalis.
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Microbial production of 2,3-butanediol by a mutagenized strain of Serratia marcescens H30.
Bioresour. Technol.
PUBLISHED: 07-01-2009
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The production of 2,3-butanediol (2,3-BD) by Serratia marcescens H30 from sucrose was studied. Medium composition for 2,3-BD production by S. marcescens H30 was optimized in shake flask fermentations using Plackett-Burman design (PB) and response surface methodology (RSM). Results indicated that yeast extract and sodium acetate had significant effects on the 2,3-BD production. And their optimal concentrations were determined by RSM. The optimal medium was used to perform fermentation experiments by S. marcescens H30 in a 3.7l bioreactor. Several feeding strategies including interim feeding, exponential feeding and constant residual sucrose concentration feeding were compared for improving 2,3-BD production. Ultimately, a suitable control strategy which combined the respiratory quotient (RQ) control with the constant residual sucrose concentration fed-batch was developed. Using this strategy, the maximum 2,3-BD concentration of 139.92 g/l with the diol (AC+BD) productivity of 3.49 g/lh and the yield of 94.67% was obtained.
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Characterization and transcriptional analyses of cDNAs encoding three trypsin- and chymotrypsin-like proteinases in Cry1Ab-susceptible and Cry1Ab-resistant strains of sugarcane borer, Diatraea saccharalis.
Insect Sci.
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Diatraea saccharalis is a major corn borer pest. Midgut serine proteinases are essential for insect growth and development. Alteration of midgut proteinases is responsible for Bt resistance development in some species. To clone midgut trypsin and chymotrypsin cDNAs and to test if the Cry1Ab resistance in D. saccharalis is associated with changes in midgut proteinases, total midgut tryptic and chymotryptic activities, cDNA sequences, and gene expressions of three trypsin and three chymotrypsin genes were comparatively examined between Cry1Ab-susceptible (Cry1Ab-SS) and Cry1Ab-resistant (Cry1Ab-RR) strains. Full-length cDNAs encoding three trypsin- and three chymotrypsin-like proteinases were sequenced from Cry1Ab-SS and Cry1Ab-RR larvae. These cDNAs code for active forms of midgut serine proteinases with all functional motifs, including signal peptide, conserved His-Asp-Ser for the catalytic triad, three pairs of cysteines for disulfide bridge configurations, and conserved substrate specificity determination residues. In general, cDNA and putative protein sequences are highly similar between Cry1Ab-SS and Cry1Ab-RR strains, except for a few nucleotide and predicted amino acid substitutions, whose function need to be further clarified. Total trypsin and chymotrypsin activities were also similar between Cry1Ab-SS and Cry1Ab-RR strains. Transcriptional levels of the trypsin and chymotrypsin genes had numerical difference between Cry1Ab-SS and Cry1Ab-RR strains, but the difference was not statistically significant. Data suggest that the development of Cry1Ab resistance in D. saccharalis was not significantly associated with these trypsins and chymotrypsins. Results clarified the role of six midgut proteinases and provided a foundation for continuing examination of potential involvement of other midgut proteinases in Bt resistance development and other important biochemical processes.
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Taurine detected using high-resolution magic angle spinning (1)H nuclear magnetic resonance: A potential indicator of early myocardial infarction.
Exp Ther Med
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Magnetic resonance spectroscopy (MRS) is a unique non-invasive method for detecting cardiac metabolic changes. However, MRS in cardiac diagnosis is limited due to insensitivity and low efficiency. Taurine (Tau) is the most abundant free amino acid in the myocardium. We hypothesized that Tau levels may indicate myocardial ischemia and early infarction. Sprague-Dawley rats were divided into seven groups according to different time points during the course of myocardial ischemia, which was induced by left anterior descending coronary artery ligation. Infarcted myocardial tissue was obtained for high-resolution magic angle spinning (1)H nuclear magnetic resonance (NMR) analysis. Results were validated via high-performance liquid chromatography. The Tau levels in the ischemic myocardial tissue were reduced significantly within 5 min compared with those in the control group (relative ratio from 20.27±6.48 to 8.81±0.04, P<0.05) and were maintained for 6 h post-ischemia. Tau levels declined more markedly (56.5%) than creatine levels (48.5%) at 5 min after ligation. This suggests that Tau may have potential as an indicator in the early detection of myocardial ischemia by (1)H MRS.
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Tumor cell-derived placental growth factor sensitizes antiangiogenic and antitumor effects of anti-VEGF drugs.
Proc. Natl. Acad. Sci. U.S.A.
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The role of placental growth factor (PlGF) in modulation of tumor angiogenesis and tumor growth remains an enigma. Furthermore, anti-PlGF therapy in tumor angiogenesis and tumor growth remains controversial in preclinical tumor models. Here we show that in both human and mouse tumors, PlGF induced the formation of dilated and normalized vascular networks that were hypersensitive to anti-VEGF and anti-VEGFR-2 therapy, leading to dormancy of a substantial number of avascular tumors. Loss-of-function using plgf shRNA in a human choriocarcinoma significantly accelerated tumor growth rates and acquired resistance to anti-VEGF drugs, whereas gain-of-function of PlGF in a mouse tumor increased anti-VEGF sensitivity. Further, we show that VEGFR-2 and VEGFR-1 blocking antibodies displayed opposing effects on tumor angiogenesis. VEGFR-1 blockade and genetic deletion of the tyrosine kinase domain of VEGFR-1 resulted in enhanced tumor angiogenesis. These findings demonstrate that tumor-derived PlGF negatively modulates tumor angiogenesis and tumor growth and may potentially serve as a predictive marker of anti-VEGF cancer therapy.
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Experimental and modeling study on nitric oxide removal in a biotrickling filter using Chelatococcus daeguensis under thermophilic condition.
Bioresour. Technol.
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In this study, the development of a thermophilic biotrickling filter (BTF) system to inoculate a newly isolated strain of Chelatococcus daeguensis TAD1 for the effective treatment of nitric oxide (NO) is described. It was successfully started up in 35days and effectively removed NO from the oxygen contained simulated gas at 50°C. A mathematical model based on the mass transfer in gas-biofilm interface and chemical oxidation in gas phase was developed. Steady-state experimental data under different inlet NO concentration and empty bed retention time (EBRT) condition were used to verify the proposed model. The model can well reproduce the experimental results and the sensitivity analysis demonstrates that the model is not dependent on the accuracy of the parameters excessively.
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Opposing effects of circadian clock genes bmal1 and period2 in regulation of VEGF-dependent angiogenesis in developing zebrafish.
Cell Rep
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Molecular mechanisms underlying circadian-regulated physiological processes remain largely unknown. Here, we show that disruption of the circadian clock by both constant exposure to light and genetic manipulation of key genes in zebrafish led to impaired developmental angiogenesis. A bmal1-specific morpholino inhibited developmental angiogenesis in zebrafish embryos without causing obvious nonvascular phenotypes. Conversely, a period2 morpholino accelerated angiogenic vessel growth, suggesting that Bmal1 and Period2 display opposing angiogenic effects. Using a promoter-reporter system consisting of various deleted vegf-promoter mutants, we show that Bmal1 directly binds to and activates the vegf promoter via E-boxes. Additionally, we provide evidence that knockdown of Bmal1 leads to impaired Notch-inhibition-induced vascular sprouting. These results shed mechanistic insight on the role of the circadian clock in regulation of developmental angiogenesis, and our findings may be reasonably extended to other types of physiological or pathological angiogenesis.
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Target-activated coumarin phototriggers specifically switch on fluorescence and photocleavage upon bonding to thiol-bearing protein.
J. Am. Chem. Soc.
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A new concept in which only the molecular target, such as a thiol-bearing protein, can activate the phototrigger has been demonstrated. Such target-activatable phototriggers comprise three parts: a 7-aminocoumarin phototrigger, an electron acceptor (maleimide) that efficiently quenches the coumarin excited state, and a caged leaving group attached to the coumarin. In the absence of mercaptans, photoinduced electron transfer between coumarin and maleimide effectively blocks both the fluorescence and photocleavage pathways. Thiol-bearing molecules, however, readily annihilate the electron acceptor and thus restore the phototrigger for photorelease of the caged cargo (e.g., biotin). Unlike traditional phototriggers, functional-group-activated phototriggers allow easy handling under ambient light, report specific bonding to the target, and enable photocleavage capability selectively at the binding site in situ, thus effectively positioning the photoreleased cargo at the target. Meanwhile, the unique feature of thiol-specific activation of the fluorescence and photocleavage make our new phototrigger a universal tool that can be used to identify accurately protein cysteine S-nitrosylation, a physiologically important posttranslational modification.
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Nitrogen Removal by Chelatococcus daeguensis TAD1 and Its Denitrification Gene Identification.
Appl. Biochem. Biotechnol.
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Chelatococcus daeguensis TAD1 was demonstrated to be an aerobic denitrifier. It can utilize not only nitrate and nitrite but also ammonium at high temperature (about 50 °C). The strain had the capability to remove 122.7 and 71.7 mg L(-1) NH4 (+)-N by 18 h at 50 and 30 °C, respectively. Triplicate heterotrophic nitrification experiments showed that 32.3 % of removed NH4 (+)-N was completely converted to nitrogen gas by 18 h at 50 °C. The denitrification genes involved in C. daeguensis TAD1 were identified and sequenced. It was found that the genes responsible for denitrification in TAD1 were napA, nirK, cnorB, and nosZ. Taken together, TAD1 can be an effective candidate for simultaneous nitrification and denitrificaton at high temperature.
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JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.