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1.
Phys Rev Lett ; 118(14): 141803, 2017 Apr 07.
Artículo en Inglés | MEDLINE | ID: mdl-28430473

RESUMEN

We present direct detection constraints on the absorption of hidden-photon dark matter with particle masses in the range 1.2-30 eV c^{-2} with the DAMIC experiment at SNOLAB. Under the assumption that the local dark matter is entirely constituted of hidden photons, the sensitivity to the kinetic mixing parameter κ is competitive with constraints from solar emission, reaching a minimum value of 2.2×10^{-14} at 17 eV c^{-2}. These results are the most stringent direct detection constraints on hidden-photon dark matter in the galactic halo with masses 3-12 eV c^{-2} and the first demonstration of direct experimental sensitivity to ionization signals <12 eV from dark matter interactions.

2.
Genet Mol Res ; 14(3): 7661-70, 2015 Jul 13.
Artículo en Inglés | MEDLINE | ID: mdl-26214446

RESUMEN

The present study aims to characterize the Cry2Ad toxin protein isolated from a Bacillus thuringiensis strain, BRC-HZP10, which have a potential insecticidal activity against larvae of the diamondback moth, Plutella xylostella (L.). The crude Bt toxin proteins were isolated and purified by cation exchange chromatography, then equilibrated with 0.2 M NaOH buffer, pH 4.0, followed by ultraviolet detection at 280 nm and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A refined Cry2Ad toxin protein with 88.34% purity was eventually obtained and used for a bioassay by feeding it to P. xylostella. The results showed conspicuous insecticidal activity towards P. xylostella with 50% lethal concentration of 6.84 µg/mL and 95% confidence interval of 5.77-7.91 mg/mL. At a concentration of 16.38 µg/mL, the intake of Cry2Ad protein significantly shortened the oviposition period and larval developmental duration, but significantly reduced the fecundity and egg hatchability of the population compared to those of control (without treatment with Cry2Ad protein) (P < 0.05). These results indicate that the Cry2Ad protein plays an effective role in controlling the population of P. xylostella.


Asunto(s)
Bacillus thuringiensis/química , Proteínas Bacterianas/aislamiento & purificación , Proteínas Bacterianas/toxicidad , Endotoxinas/aislamiento & purificación , Endotoxinas/toxicidad , Proteínas Hemolisinas/aislamiento & purificación , Proteínas Hemolisinas/toxicidad , Insecticidas/toxicidad , Mariposas Nocturnas/crecimiento & desarrollo , Pruebas de Toxicidad , Animales , Toxinas de Bacillus thuringiensis , Cationes , Cromatografía por Intercambio Iónico , Electroforesis en Gel de Poliacrilamida , Mariposas Nocturnas/efectos de los fármacos , Estándares de Referencia , Análisis de Regresión , Albúmina Sérica Bovina/metabolismo , Factores de Tiempo
3.
Rev. bras. pesqui. méd. biol ; Braz. j. med. biol. res;43(10): 931-941, Oct. 2010. ilus
Artículo en Inglés | LILACS | ID: lil-561226

RESUMEN

Refractory and relapsed leukemia is a major problem during cancer therapy, which is due to the aberrant activation of Wnt/β-catenin signaling pathway. Activation of this pathway is promoted by wingless (Wnt) proteins and induces co-activator β-catenin binding to lymphoid enhancer factor (LEF)/T-cell factor protein (TCF). To provide a convenient system for the screening of anti-Wnt/β-catenin agents, we designed a bi-functional pGL4-TOP reporter plasmid that contained 3X β-catenin/LEF/TCF binding sites and a selectable marker. After transfection and hygromycin B selection, HEK 293-TOP and Jurkat-TOP stable clones were established. The luciferase activity in the stable clone was enhanced by the recombinant Wnt-3A (rWnt-3A; 100-400 ng/mL) and GSK3β inhibitor (2’Z,3’E)-6-bromoindirubin-3’-oxime (BIO; 5 µM) but was inhibited by aspirin (5 mM). Using this reporter model, we found that norcantharidin (NCTD; 100 µM) reduced 80 percent of rWnt-3A-induced luciferase activity. Furthermore, 50 µM NCTD inhibited 38 percent of BIO-induced luciferase activity in Jurkat-TOP stable cells. Employing ³H-thymidine uptake assay and Western blot analysis, we confirmed that NCTD (50 µM) significantly inhibited proliferation of Jurkat cells by 64 percent, which are the dominant β-catenin signaling cells and decreased β-catenin protein in a concentration-dependent manner. Thus, we established a stable HEK 293-TOP clone and successfully used it to identify the Wnt/β-catenin signaling inhibitor NCTD.


Asunto(s)
Humanos , Compuestos Bicíclicos Heterocíclicos con Puentes/farmacología , Indoles/antagonistas & inhibidores , Oximas/antagonistas & inhibidores , Transducción de Señal/efectos de los fármacos , Proteínas Wnt/antagonistas & inhibidores , beta Catenina/antagonistas & inhibidores , Proliferación Celular/efectos de los fármacos , Evaluación Preclínica de Medicamentos/métodos , Genes Reporteros/fisiología , Células Jurkat , Luciferasas/metabolismo , Plásmidos/efectos de los fármacos , Plásmidos/genética , Transfección/métodos , Proteínas Wnt/metabolismo , beta Catenina/metabolismo
4.
Braz J Med Biol Res ; 43(10): 931-41, 2010 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-20835687

RESUMEN

Refractory and relapsed leukemia is a major problem during cancer therapy, which is due to the aberrant activation of Wnt/ß-catenin signaling pathway. Activation of this pathway is promoted by wingless (Wnt) proteins and induces co-activator ß-catenin binding to lymphoid enhancer factor (LEF)/T-cell factor protein (TCF). To provide a convenient system for the screening of anti-Wnt/ß-catenin agents, we designed a bi-functional pGL4-TOP reporter plasmid that contained 3X ß-catenin/LEF/TCF binding sites and a selectable marker. After transfection and hygromycin B selection, HEK 293-TOP and Jurkat-TOP stable clones were established. The luciferase activity in the stable clone was enhanced by the recombinant Wnt-3A (rWnt-3A; 100-400 ng/mL) and GSK3ß inhibitor (2'Z,3'E)-6-bromoindirubin-3'-oxime (BIO; 5 µM) but was inhibited by aspirin (5 mM). Using this reporter model, we found that norcantharidin (NCTD; 100 µM) reduced 80% of rWnt-3A-induced luciferase activity. Furthermore, 50 µM NCTD inhibited 38% of BIO-induced luciferase activity in Jurkat-TOP stable cells. Employing ³H-thymidine uptake assay and Western blot analysis, we confirmed that NCTD (50 µM) significantly inhibited proliferation of Jurkat cells by 64%, which are the dominant ß-catenin signaling cells and decreased ß-catenin protein in a concentration-dependent manner. Thus, we established a stable HEK 293-TOP clone and successfully used it to identify the Wnt/ß-catenin signaling inhibitor NCTD.


Asunto(s)
Compuestos Bicíclicos Heterocíclicos con Puentes/farmacología , Indoles/antagonistas & inhibidores , Oximas/antagonistas & inhibidores , Transducción de Señal/efectos de los fármacos , Proteínas Wnt/antagonistas & inhibidores , beta Catenina/antagonistas & inhibidores , Proliferación Celular/efectos de los fármacos , Evaluación Preclínica de Medicamentos/métodos , Genes Reporteros/fisiología , Células HEK293 , Humanos , Células Jurkat , Luciferasas/metabolismo , Plásmidos/efectos de los fármacos , Plásmidos/genética , Transfección/métodos , Proteínas Wnt/metabolismo , Proteína Wnt3 , Proteína Wnt3A , beta Catenina/metabolismo
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