Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 41
Filtrar
Mais filtros

Base de dados
Tipo de documento
Intervalo de ano de publicação
1.
J Integr Plant Biol ; 64(10): 1866-1882, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35904035

RESUMO

Salt stress and flowering time are major factors limiting geographic adaptation and yield productivity in soybean (Glycine max). Although improving crop salt tolerance and latitude adaptation are essential for efficient agricultural production, whether and how these two traits are integrated remains largely unknown. Here, we used a genome-wide association study to identify a major salt-tolerance locus controlled by E2, an ortholog of Arabidopsis thaliana GIGANTEA (GI). Loss of E2 function not only shortened flowering time and maturity, but also enhanced salt-tolerance in soybean. E2 delayed soybean flowering by enhancing the transcription of the core flowering suppressor gene E1, thereby repressing Flowering Locus T (FT) expression. An E2 knockout mutant e2CR displayed reduced accumulation of reactive oxygen species (ROS) during the response to salt stress by releasing peroxidase, which functions in ROS scavenging to avoid cytotoxicity. Evolutionary and population genetic analyses also suggested that loss-of-function e2 alleles have been artificially selected during breeding for soybean adaptation to high-latitude regions with greater salt stress. Our findings provide insights into the coupled selection for adaptation to both latitude and salt stress in soybean; and offer an ideal target for molecular breeding of early-maturing and salt-tolerant cultivars.


Assuntos
Arabidopsis , Glycine max , Glycine max/genética , Tolerância ao Sal/genética , Espécies Reativas de Oxigênio , Flores/genética , Estudo de Associação Genômica Ampla , Melhoramento Vegetal , Arabidopsis/genética , Peroxidases/genética , Regulação da Expressão Gênica de Plantas
2.
Org Biomol Chem ; 15(19): 4191-4198, 2017 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-28443921

RESUMO

A highly enantioselective conjugate addition of 2-substituted benzofuran-3(2H)-ones to α,ß-unsaturated ketones promoted by chiral copper complexes has been developed, affording the Michael addition products with quaternary stereocenters in good to high yields (up to 95% yield) with excellent enantioselectivities (up to 99% ee). The chiral Michael adducts could be readily converted to the polycyclic benzofuran-type framework via the Robinson annulation.

3.
Proc Natl Acad Sci U S A ; 111(32): 11774-9, 2014 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-25071169

RESUMO

Impressive responses have been observed in patients treated with checkpoint inhibitory anti-programmed cell death-1 (PD-1) or anti-cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) antibodies. However, immunotherapy against poorly immunogenic cancers remains a challenge. Here we report that treatment with both anti-PD-1 and anti-CTLA-4 antibodies was unable to eradicate large, modestly immunogenic CT26 tumors or metastatic 4T1 tumors. Cotreatment with epigenetic-modulating drugs and checkpoint inhibitors markedly improved treatment outcomes, curing more than 80% of the tumor-bearing mice. Functional studies revealed that the primary targets of the epigenetic modulators were myeloid-derived suppressor cells (MDSCs). A PI3K inhibitor that reduced circulating MDSCs also eradicated 4T1 tumors in 80% of the mice when combined with immune checkpoint inhibitors. Thus, cancers resistant to immune checkpoint blockade can be cured by eliminating MDSCs.


Assuntos
Imunoterapia/métodos , Células Mieloides/imunologia , Metástase Neoplásica/imunologia , Metástase Neoplásica/terapia , Animais , Anticorpos Monoclonais/administração & dosagem , Azacitidina/administração & dosagem , Benzamidas/administração & dosagem , Antígeno CTLA-4/antagonistas & inibidores , Antígeno CTLA-4/imunologia , Linhagem Celular Tumoral , Neoplasias Colorretais/imunologia , Neoplasias Colorretais/secundário , Neoplasias Colorretais/terapia , Terapia Combinada , Epigênese Genética/efeitos dos fármacos , Feminino , Inibidores de Histona Desacetilases/administração & dosagem , Humanos , Neoplasias Mamárias Experimentais/imunologia , Neoplasias Mamárias Experimentais/secundário , Neoplasias Mamárias Experimentais/terapia , Camundongos , Camundongos Endogâmicos BALB C , Células Mieloides/efeitos dos fármacos , Metástase Neoplásica/genética , Inibidores de Fosfoinositídeo-3 Quinase , Receptor de Morte Celular Programada 1/antagonistas & inibidores , Receptor de Morte Celular Programada 1/imunologia , Piridinas/administração & dosagem
4.
Am J Physiol Cell Physiol ; 310(8): C692-700, 2016 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-26911280

RESUMO

The phosphorylation of the myosin regulatory light chain (RLC) is an important modulator of skeletal muscle performance and plays a key role in posttetanic potentiation and staircase potentiation of twitch contractions. The structural basis for these phenomena within the filament lattice has not been thoroughly investigated. Using a synchrotron radiation source at SPring8, we obtained X-ray diffraction patterns from skinned rabbit psoas muscle fibers before and after phosphorylation of myosin RLC in the presence of myosin light chain kinase, calmodulin, and calcium at a concentration below the threshold for tension development ([Ca(2+)] = 10(-6.8)M). After phosphorylation, the first myosin layer line slightly decreased in intensity at ∼0.05 nm(-1)along the equatorial axis, indicating a partial loss of the helical order of myosin heads along the thick filament. Concomitantly, the (1,1/1,0) intensity ratio of the equatorial reflections increased. These results provide a firm structural basis for the hypothesis that phosphorylation of myosin RLC caused the myosin heads to move away from the thick filaments towards the thin filaments, thereby enhancing the probability of interaction with actin. In contrast, 2,3-butanedione monoxime (BDM), known to inhibit contraction by impeding phosphate release from myosin, had exactly the opposite effects on meridional and equatorial reflections to those of phosphorylation. We hypothesize that these antagonistic effects are due to the acceleration of phosphate release from myosin by phosphorylation and its inhibition by BDM, the consequent shifts in crossbridge equilibria leading to opposite changes in abundance of the myosin-ADP-inorganic phosphate complex state associated with helical order of thick filaments.


Assuntos
Diacetil/análogos & derivados , Contração Muscular/fisiologia , Fibras Musculares Esqueléticas/fisiologia , Fibras Musculares Esqueléticas/ultraestrutura , Cadeias Leves de Miosina/fisiologia , Cadeias Leves de Miosina/ultraestrutura , Animais , Células Cultivadas , Diacetil/farmacologia , Masculino , Contração Muscular/efeitos dos fármacos , Fibras Musculares Esqueléticas/efeitos dos fármacos , Fosforilação/efeitos dos fármacos , Coelhos , Difração de Raios X/métodos
5.
PLoS Genet ; 9(12): e1004071, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24385939

RESUMO

During meiosis, Structural Maintenance of Chromosome (SMC) complexes underpin two fundamental features of meiosis: homologous recombination and chromosome segregation. While meiotic functions of the cohesin and condensin complexes have been delineated, the role of the third SMC complex, Smc5/6, remains enigmatic. Here we identify specific, essential meiotic functions for the Smc5/6 complex in homologous recombination and the regulation of cohesin. We show that Smc5/6 is enriched at centromeres and cohesin-association sites where it regulates sister-chromatid cohesion and the timely removal of cohesin from chromosomal arms, respectively. Smc5/6 also localizes to recombination hotspots, where it promotes normal formation and resolution of a subset of joint-molecule intermediates. In this regard, Smc5/6 functions independently of the major crossover pathway defined by the MutLγ complex. Furthermore, we show that Smc5/6 is required for stable chromosomal localization of the XPF-family endonuclease, Mus81-Mms4(Eme1). Our data suggest that the Smc5/6 complex is required for specific recombination and chromosomal processes throughout meiosis and that in its absence, attempts at cell division with unresolved joint molecules and residual cohesin lead to severe recombination-induced meiotic catastrophe.


Assuntos
Proteínas de Ciclo Celular/genética , Segregação de Cromossomos/genética , Recombinação Homóloga/genética , Meiose/genética , Proteínas de Saccharomyces cerevisiae/genética , Adenosina Trifosfatases/genética , Centrômero , Proteínas Cromossômicas não Histona/genética , Reparo do DNA/genética , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Endonucleases/genética , Endonucleases/metabolismo , Complexos Multiproteicos/genética , Saccharomyces cerevisiae , Proteínas de Saccharomyces cerevisiae/metabolismo , Coesinas
6.
Org Biomol Chem ; 13(37): 9593-9, 2015 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-26257265

RESUMO

A new kind of recyclable and reusable PEG-supported Jørgensen-Hayashi catalyst is synthesized for the first time and proven to be efficient for the enamine-catalyzed asymmetric Michael reaction with generally moderate to good diastereoselectivity and high to excellent enantioselectivity (up to 6 : 1 dr, 99% ee). The prepared PEG-supported catalyst can be recovered eight times and was found to provide similar diastereoselectivity and enantioselectivity to unsupported functional catalysts.


Assuntos
Aldeídos/química , Cetonas/química , Polietilenoglicóis/química , Catálise
7.
Biol Pharm Bull ; 37(1): 113-22, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24141262

RESUMO

As part of the efforts to understand isoflavonoid metabolism in Pueraria lobata at the molecular level, the cDNAs encoding two divergent 4-coumarate : coenzyme A ligases (4CLs, designated Pl4CL1 and Pl4CL2, respectively) were isolated from P. lobata roots. Sequence analysis revealed that Pl4CL1 had an N-terminal extension of twenty-one amino acid residues compared to Pl4CL2. Phylogenetic analysis showed that Pl4CL1 and Pl4CL2 fell into angiosperm Class II and Class I, respectively. Through in vitro biochemical assays, both Pl4CLs were found to have the capacity to utilize 4-coumarate and trans-cinnamate as substrates, while neither of them could convert sinapate. Pl4CL2 had a broader substrate specificity than Pl4CL1. The affinity of Pl4CL1 for 4-coumarate was 2.6-fold higher than that of Pl4CL2 (with the Km values of 3.5 µM and 9.1 µM, respectively). Combining the dataset including gene expression profiles, metabolites measurements, and biochemical properties, our results indicated that Pl4CL1, just as other angiosperm Class II 4CLs, might play a role in isoflavone biosynthesis in P. lobata, while Pl4CL2 belongs to angiosperm Class I, and may function as a housekeeping enzyme concerning lignification.


Assuntos
Aminoácidos/análise , Cinamatos/metabolismo , Coenzima A Ligases , Ácidos Cumáricos/metabolismo , Isoflavonas/biossíntese , Lignanas/biossíntese , Pueraria , Sequência de Aminoácidos , Clonagem Molecular , Coenzima A Ligases/química , Coenzima A Ligases/genética , Coenzima A Ligases/metabolismo , DNA Complementar , Dados de Sequência Molecular , Filogenia , Raízes de Plantas/enzimologia , Raízes de Plantas/metabolismo , Pueraria/enzimologia , Pueraria/genética , Pueraria/metabolismo , Especificidade por Substrato
8.
Plant Cell Rep ; 33(7): 1173-85, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24700248

RESUMO

KEY MESSAGE: A novel isoflavone 7- O -glucosyltransferase PlUGT1 was isolated from Pueraria lobata . PlUGT1 could convert daidzein to daidzin, genistein to genistin as well as formononetin to ononin. Pueraria lobata roots are traditionally consumed as a rich source of isoflavone glycosides that have various human health benefits. However, to date, the genes encoding isoflavone UDP-glycosyltransferases (UGTs) have only been isolated from the roots of soybean seedlings (GmIF7GT), soybean seeds (UGT73F2) and Glycyrrhiza echinata cell suspension cultures (GeIF7GT). To investigate the isoflavone metabolism in P. lobata, 40 types of partial UGT cDNAs were isolated from P. lobata, and seven full-length UGT candidates with preferential expression in roots were identified. Functional assays in yeast (Saccharomyces cerevisiae) revealed that one of these UGT candidates, designated PlUGT1 (official UGT designation UGT88E12), efficiently glycosylated isoflavone aglycones at the 7-hydroxy group. Recombinant PlUGT1 purified from Escherichia coli cells was characterized and shown to be relatively specific for isoflavone aglycones, while flavonoid substrates were poorly accepted. The biochemical results suggested that PlUGT1 was an isoflavone 7-O-glucosyltransferase. The deduced amino acid sequence of PlUGT1 shared only 26 % identity with GeIF7GT, 27 % with UGT73F2 and 63 % with GmIF7GT. The PlUGT1 gene was highly expressed in P. lobata roots relative to other organs and strongly induced by methyl jasmonate signal in P. lobata cell suspension culture. The transcript abundance of PlUGT1 was correlated with the accumulation pattern of isoflavone glycosides such as daidzin in P. lobata plants or in cell suspension culture. The biochemical properties and gene expression profile supported the idea that PlUGT1 could play a role in isoflavone glycosylation in P. lobata.


Assuntos
Glucosiltransferases/metabolismo , Proteínas de Plantas/metabolismo , Pueraria/metabolismo , Acetatos/farmacologia , Clonagem Molecular , Ciclopentanos/farmacologia , Glucosídeos/metabolismo , Glucosiltransferases/genética , Isoflavonas/metabolismo , Dados de Sequência Molecular , Oxilipinas/farmacologia , Filogenia , Proteínas de Plantas/genética , Raízes de Plantas/enzimologia , Pueraria/efeitos dos fármacos , Pueraria/genética
9.
Nanoscale ; 16(9): 4826-4840, 2024 Feb 29.
Artigo em Inglês | MEDLINE | ID: mdl-38312054

RESUMO

The temperature-controlled relationship between the mechanical properties and deformation mechanism of tantalum (Ta) enables the extension of its application potential in various areas of life, including energy and electronics industries. In this work, the microstructure and deformation behavior of nanocrystalline superior-deformed Ta have been investigated in a wide temperature range. The structural analysis revealed that the high-performance Ta consists of several different substructures, with an average size of about 20 nm. The tensile behavior of nanocrystalline Ta (NC-Ta) was analysed and simulated at various temperatures from 100 K to 1500 K by the molecular dynamics (MD) method. It is shown that with increasing average grain size, the elastic modulus of NC-Ta linearly increases, and the impact factor reaches a value close to 1.8. The critical grain size, as obtained from the Hall-Petch relationship, was found to be about 8.2 nm. For larger grains, the flow stress follows the Hall-Petch relationship, and the thermal behavior of twin bands determines the deformation process. On the other hand, when grains are smaller than the critical size, the relationship between the flow stress and structure transforms into the inverse Hall-Petch relationship, and the deformation mechanism is controlled by grain rotation, boundary sliding or atomic migration. The results of numerical simulations revealed that temperature significantly affects the critical grain size for the plastic deformation of NC-Ta. In addition, it is demonstrated that both the elastic modulus and dislocation density decrease with increasing temperature. These findings provide guidance for the design of polycrystalline tantalum materials with tailored mechanical properties for specific industrial applications such as heat exchangers and condensers in aerospace, bone substitutes in biomedicine, and surface acoustic wave filters or capacitors in electronics.

10.
Mol Cell Biochem ; 384(1-2): 263-8, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24122417

RESUMO

microRNA-9 (miR-9) has been found to be upregulated along with tumor progression of gliomas by microarray-based expression profiling, and also be strongly linked to glioblastoma subtypes. However, its prognostic value in glioma is still elusive. miR-9 expression in human gliomas and nonneoplastic brain tissues was measured by real-time quantitative RT-PCR assay. miR-9 expression in glioma tissues was significantly higher than that in corresponding nonneoplastic brain tissues (P\0.001). The increased expression of miR-9 was more frequently observed in glioma tissues with high WHO grade than those with low WHO grade tissues (P = 0.001). The expression levels of miR-9 in glioma tissues with low Karnofsky performance score (KPS) were also significantly higher than those with high KPS (P = 0.008). Moreover, the overall survival of glioma patients with high miR-9 expression was obviously lower than that with low miR-9 expression (P\0.001). Multivariate analysis further showed that high miR-9 expression was an independent prognostic factor for overall survival in glioma patients (P = 0.01). More importantly, the subgroup analyses indicated that the overall survival of glioma patients with high WHO grade (III­IV) was significantly worse for high miR-9 expression group than for low miR-9 expression group (P\0.001), but no significant difference was found for patients with low WHO grade (I­II). These findings suggest for the first time that the increased expression of miR-9 may play an important role in tumor progression in human gliomas. miR-9 might be a useful marker for predicting the clinical outcome of glioma patients, especially for advanced subtypes.


Assuntos
Neoplasias Encefálicas/genética , Neoplasias Encefálicas/mortalidade , Glioma/genética , Glioma/mortalidade , MicroRNAs/biossíntese , Adolescente , Adulto , Idoso , Biomarcadores Tumorais/genética , Criança , Progressão da Doença , Feminino , Expressão Gênica , Regulação Neoplásica da Expressão Gênica/genética , Humanos , Masculino , MicroRNAs/genética , MicroRNAs/metabolismo , Pessoa de Meia-Idade , Prognóstico , Sobrevida , Regulação para Cima , Adulto Jovem
11.
J Org Chem ; 78(3): 1254-9, 2013 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-23286458

RESUMO

The organocatalytic Michael reaction of ketones with γ-monohalonitrodienes catalyzed by chiral prolinethiol ether under solvent-free conditions was developed. The described method represents a novel approach for accessing highly functionalized monohaloalkenes with α, ß-stereocenters of up to >99% ee.


Assuntos
Alcenos/química , Alcenos/síntese química , Éter/química , Hidrocarbonetos Halogenados/química , Hidrocarbonetos Halogenados/síntese química , Prolina/química , Solventes/química , Compostos de Sulfidrila/química , Catálise , Estrutura Molecular , Estereoisomerismo
12.
Artigo em Inglês | MEDLINE | ID: mdl-22259397

RESUMO

The title compound, C(14)H(14)BrNO(5), has two chiral C atoms. The quaternary C atom in the oxolanone ring has an S configuration, while the adjacent tertiary C atom has an R configuration. The oxolanone ring adopts an envelope conformation, with the flap C atom lying 0.298 (3) Šfrom the mean plane of the remaining four atoms. In the crystal, mol-ecules are connected into chains along [010] via weak C-H⋯O hydrogen bonds.

13.
Acta Crystallogr Sect E Struct Rep Online ; 68(Pt 7): o2065, 2012 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-22807886

RESUMO

The title compound, C(10)H(11)NO(2), adopts an E conformation about the C=C bond. The C=C-C=C torsion angle is 32.5 (3)°. The crystal structure features weak inter-molecular C-H⋯O inter-actions.

14.
Acta Crystallogr Sect E Struct Rep Online ; 68(Pt 8): o2359, 2012 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-22904825

RESUMO

The title compound, C(9)H(8)N(2)O(4), adopts an E conformation about the C=C bond. The CH(phen-yl)-C(phen-yl)-CH-C(-NO(2)) torsion angle is -57.7 (3)°. The crystal structure features weak inter-molecular C-H⋯O inter-actions.

15.
Acta Crystallogr Sect E Struct Rep Online ; 68(Pt 2): o499, 2012 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-22347100

RESUMO

The title compoud, C(19)H(18)BrNO(5), was synthesized by an organocatalytic reaction. The aymmetric unit contains two independent mol-ecules, in each of which the carbon between the two carbonyl groups adopts an R configuration, while the adjacent C atom has an S configuration. The dihedral angle between the two benzene rings is different in the two mol-ecules [11.64 (3) and 58.96 (4)°].

16.
Acta Crystallogr Sect E Struct Rep Online ; 67(Pt 4): o983, 2011 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-21754241

RESUMO

The title compound, C(7)H(7)NO(2)S, adopts an E conformation about the C=C bond. The torsion angle C=C-C-C is -177.7 (3)°. The crystal structure features weak inter-molecular by C-H⋯O inter-actions.

17.
Front Neurosci ; 15: 784721, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-35058742

RESUMO

Purpose: Tinnitus is a common but obscure auditory disease to be studied. This study will determine whether the connectivity features in electroencephalography (EEG) signals can be used as the biomarkers for an efficient and fast diagnosis method for chronic tinnitus. Methods: In this study, the resting-state EEG signals of tinnitus patients with different tinnitus locations were recorded. Four connectivity features [including the Phase-locking value (PLV), Phase lag index (PLI), Pearson correlation coefficient (PCC), and Transfer entropy (TE)] and two time-frequency domain features in the EEG signals were extracted, and four machine learning algorithms, included two support vector machine models (SVM), a multi-layer perception network (MLP) and a convolutional neural network (CNN), were used based on the selected features to classify different possible tinnitus sources. Results: Classification accuracy was highest when the SVM algorithm or the MLP algorithm was applied to the PCC feature sets, achieving final average classification accuracies of 99.42 or 99.1%, respectively. And based on the PLV feature, the classification result was also particularly good. And MLP ran the fastest, with an average computing time of only 4.2 s, which was more suitable than other methods when a real-time diagnosis was required. Conclusion: Connectivity features of the resting-state EEG signals could characterize the differentiation of tinnitus location. The connectivity features (PCC and PLV) were more suitable as the biomarkers for the objective diagnosing of tinnitus. And the results were helpful for clinicians in the initial diagnosis of tinnitus.

18.
Org Biomol Chem ; 8(11): 2505-8, 2010 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-20414483

RESUMO

The highly enantioselective Michael addition reaction of ketones to nitrodienes was promoted efficiently by the accessible and fine-tunable organocatalytic system of pyrrolidinyl-thioimidazole and chiral thioureido acid. The corresponding adducts were afforded in good yields with high diastereoselectivities (up to 99 : 1) and excellent enantioselectivities (up to 99% ee).

19.
Nanotechnology ; 21(11): 115102, 2010 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-20173245

RESUMO

pH-responsive (1)O(2) photosensitizing systems may serve as selective photodynamic therapy (PDT) agents by targeting the acidic interstitial fluid of many kinds of tumors. In this work, we present a pH-responsive nanoparticle-based platform for controllable (1)O(2) generation, in which a hydrophobic (1)O(2) photosensitizer (meso-tetraphenylporphyrin, TPP) and a pH indicator (Bromocresol Purple, BCP, or Bromothymol Blue, BTB) are simultaneously encapsulated in organically modified silica nanoparticles (OSNP). In basic conditions, the pH indicator absorbs light competitively and thus restricts sensitizer excitation. In acidic solution, the blue shifted absorption of the pH indicator allows the efficient excitation of the sensitizer. The pH indicator serves as an 'inner filter' to modulate effectively the excitation of the sensitizer and thus the (1)O(2) generation efficiency.


Assuntos
Nanopartículas/química , Oxigênio/química , Fármacos Fotossensibilizantes/química , Dióxido de Silício/química , Concentração de Íons de Hidrogênio , Nanopartículas/ultraestrutura , Porfirinas/química
20.
Acta Crystallogr Sect E Struct Rep Online ; 66(Pt 7): o1781, 2010 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-21587993

RESUMO

The asymmetric unit of the title compound, C(9)H(8)N(2)O(4), contains two crystallographically independent mol-ecules, both of which adopt an E configuration about the C=C bond. In the crystal, the mol-ecules stack into columns along the c axis through π-π inter-actions, with centroid-centroid distances of 3.695 (3) and 3.804 (3) Å. The columns are further connected into a three-dimensional network by C-H⋯O hydrogen bonds.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA