The Mre11-Rad50-Nbs1 complex mediates activation of TopBP1 by ATM

The activation of ATR-ATRIP in response to double-stranded DNA breaks (DSBs) depends upon ATM in human cells and Xenopus egg extracts. One important aspect of this dependency involves regulation of TopBP1 by ATM. In Xenopus egg extracts, ATM associates with TopBP1 and thereupon phosphorylates it on S1131. This phosphorylation enhances the capacity of TopBP1 to activate the ATR-ATRIP complex. We show that TopBP1 also interacts with the Mre11-Rad50-Nbs1 (MRN) complex in egg extracts in a checkpoint-regulated manner. This interaction involves the Nbs1 subunit of the complex. ATM can no longer interact with TopBP1 in Nbs1-depleted egg extracts, which suggests that the MRN complex helps to bridge ATM and TopBP1 together. The association between TopBP1 and Nbs1 involves the first pair of BRCT repeats in TopBP1. In addition, the two tandem BRCT repeats of Nbs1 are required for this binding. Functional studies with mutated forms of TopBP1 and Nbs1 suggested that the BRCT-dependent association of these proteins is critical for a normal checkpoint response to DSBs. These findings suggest that the MRN complex is a crucial mediator in the process whereby ATM promotes the TopBP1-dependent activation of ATR-ATRIP in response to DSBs

Rad17 Plays a Central Role in Establishment of the Interaction between TopBP1 and the Rad9-Hus1-Rad1 Complex at Stalled Replication Forks

Rad17 is critical for the ATR-dependent activation of Chk1 during checkpoint responses. It is known that Rad17 loads the Rad9-Hus1-Rad1 (9-1-1) complex onto DNA. We show that Rad17 also mediates the interaction of 9-1-1 with the ATR-activating protein TopBP1 in Xenopus egg extracts. Studies with Rad17 mutants indicate that binding of ATP to Rad17 is essential for the association of 9-1-1 and TopBP1. Furthermore, hydrolysis of ATP by Rad17 is necessary for the loading of 9-1-1 onto DNA and the elevated, checkpoint-dependent accumulation of TopBP1 on chromatin. Significantly, a mutant 9-1-1 complex that cannot bind TopBP1 has a normal capacity to promote elevated accumulation of TopBP1 on chromatin. Taken together, we propose the following mechanism. First, Rad17 loads 9-1-1 onto DNA. Second, TopBP1 accumulates on chromatin in a manner that depends on both Rad17 and 9-1-1. Finally, 9-1-1 and TopBP1 dock in a Rad17-dependent manner before activation of Chk1

Estructura y evolución del desempleo en el área metropolitana de Cali, 1988-1998: ¿existe histeresis?

Aquí hay un análisis de los componentes estructurales del desempleo: tasa de entrada o frecuencia del desempleo y duración media del mismo. Luego se hace el análisis de la existencia de raíces unitarias en la serie tasa de desempleo. La hipótesis de histéresis en el desempleo, tanto absoluta como parcial, resulta rechazada por la evidencia empírica. Un uso inadecuado del test de Dickey y Fuller puede llevar a la conclusión contraria, cuando sólo se consideran procesos lineales en el contraste. La inexistencia de una raíz unitaria se mantiene para la tasa de entrada, el tiempo medio de búsqueda y la duración media del desempleo. Estas variables pueden representarse bien con procesos de tendencia determinística lineal, quebrada o cuadrática

Aspectos claves de la logística del transporte multimodal en el caribe Colombiano y américa para potencializar las actividades comerciales

Si bien es cierto existen diferentes modalidades de transporte, como el marítimo- fluvial, el terrestre y sus modalidades; el aéreo, las empresas cada día se especializan en llevar sus mercancías de un lugar a otro, algunas son reconocidas como OTM, Operadores de Transporte Multimodal, en su ges-tión necesitan vías, por lo que este artículo tiene como objeto indagar referentes en materia logística portuaria, terrestre y relacionados con las actividades comerciales. Se hizo mediante la búsqueda de autores relacionados con la temática y se describen rasgos, características de las ciudades, sus Puertos, infraestructura, logística a partir de artículos, revistas especializadas y libros, por lo que es un artículo de revisión, en él se concluye que los gobiernos, las empresas y la academia deben aunar esfuerzos para integrar el Caribe con América

Una aproximación econométrica a la tasa de retorno social de la educación

Cuando se mide la tasa de retorno de la educación, agrupando según la localización en viviendas contiguas, la rentabilidad social resulta mucho mayor que la individual. Usando una modelización que reconoce simultáneamente al individuo por un lado, y los determinantes del nivel agregado por otro, se encuentra que la diferencia obedece a la presencia de externalidades. La prima diferencial en los ingresos que genera la pertenencia a un segmento, depende a su vez de la concentración de capital humano en el mismo y explica la mayor rentabilidad social. Este resultado contradice anteriores investigaciones que concluyeron que la tasa social de retorno de la educación era inferior a la respectiva tasa privada. Una implicación inmediata de este hallazgo es la recomendación de una urgente revisión de las políticas económicas que pretenden trasladar recursos de la universidad pública a la escuela primaria

Context specificity of post-error and post-conflict cognitive control adjustments

There has been accumulating evidence that cognitive control can be adaptively regulated by monitoring for processing conflict as an index of online control demands. However, it is not yet known whether top-down control mechanisms respond to processing conflict in a manner specific to the operative task context or confer a more generalized benefit. While previous studies have examined the taskset-specificity of conflict adaptation effects, yielding inconsistent results, controlrelated performance adjustments following errors have been largely overlooked. This gap in the literature underscores recent debate as to whether post-error performance represents a strategic, control-mediated mechanism or a nonstrategic consequence of attentional orienting. In the present study, evidence of generalized control following both high conflict correct trials and errors was explored in a task-switching paradigm. Conflict adaptation effects were not found to generalize across tasksets, despite a shared response set. In contrast, post-error slowing effects were found to extend to the inactive taskset and were predictive of enhanced post-error accuracy. In addition, post-error performance adjustments were found to persist for several trials and across multiple task switches, a finding inconsistent with attentional orienting accounts of post-error slowing. These findings indicate that error-related control adjustments confer a generalized performance benefit and suggest dissociable mechanisms of post-conflict and post-error control. © 2014 Forster, Cho

Performance breakdown effects dissociate from error detection effects in typing

Mistakes in skilled performance are often observed to be slower than correct actions. This error slowing has been associated with cognitive control processes involved in performance monitoring and error detection. A limited literature on skilled actions, however, suggests that preerror actions may also be slower than accurate actions. This contrasts with findings from unskilled, discrete trial tasks, where preerror performance is usually faster than accurate performance. We tested 3 predictions about error-related behavioural changes in continuous typing performance. We asked participants to type 100 sentences without visual feedback. We found that (a) performance before errors was no different in speed than that before correct key-presses, (b) error and posterror key-presses were slower than matched correct key-presses, and (c) errors were preceded by greater variability in speed than were matched correct key-presses. Our results suggest that errors are preceded by a behavioural signature, which may indicate breakdown of fluid cognition, and that the effects of error detection on performance (error and posterror slowing) can be dissociated from breakdown effects (preerror increase in variability). © 2013 © 2013 The Experimental Psychology Society

Batch adsorption and fixed bed column of the B39 dye on granular activated carbon B39

Los colorantes están usualmente presentes en los efluentes acuosos de muchas industrias, como la textil, del cuero, el papel, la imprenta y cosméticos. La efectividad de la adsorción de colorantes presentes en aguas residuales, empleando adsorbentes de bajo costo, ha permitido la extensión de esta técnica de remoción, por encima de otros métodos de tratamiento. Este trabajo investigó la capacidad de adsorción de un carbón activado comercial (CA) en la remoción del colorante reactivo Blue 39 (B39) en disolución acuosa a 25°C. Los datos experimentales del estudio en lote realizado a diferentes pH (6-8) y concentraciones iniciales de B39 (5-200 mg dm 3), se ajustan satisfactoriamente al modelo de isoterma de Freundlich, presentando una capacidad máxima de adsorción en monocapa de 17,7 mg g-1 a pH 8. El estudio dinámico a diferentes alturas del lecho (1, 3 y 5 cm), flujos volumétricos (1 y 5 cm3 min-1) y concentración inicial de 5,5 mg dm-3, muestra que el tiempo de servicio de la columna y la capacidad de remoción mejoran cuando la altura aumenta y el flujo volumétrico disminuye. El modelo del tiempo de servicio de la altura del lecho (BDST) se aplicó a los datos experimentales ajustándose de manera aceptable.Abstract: Dyes are usually present in water effluents of many industries, such as textiles, leather, paper, printing and cosmetics. The effectiveness of the adsorption of dyes in wastewater using inexpensive adsorbents has enabled the extension of this technique for removal, over other methods of treatment. This study investigated the adsorption capacity of a commercial activated carbon (AC) on the removal of reactive dye Blue 39 (B39) in water solution at 25°C. The experimental ,conform to the model of Freundlich isotherm, presenting a maximum adsorption capacity monolayer 17.7 mg g-1 at pH 8. The dynamic study at different heights of the bed (1, 3 and 5 cm), flow rates (1 and 5 cm3 min-1) and initial concentration of 5,5 mg dm-3, shows that the time service and the capacity column removal improved when the height increases and the flow rate decreases. The model of the service time of the bed height (BDST) was applied to the experimental data at an acceptable conform

Batch adsorption and fixed bed column of the B39 dye on granular activated carbon B39

Los colorantes están usualmente presentes en los efluentes acuosos de muchas industrias, como la textil, del cuero, el papel, la imprenta y cosméticos. La efectividad de la adsorción de colorantes presentes en aguas residuales, empleando adsorbentes de bajo costo, ha permitido la extensión de esta técnica de remoción, por encima de otros métodos de tratamiento. Este trabajo investigó la capacidad de adsorción de un carbón activado comercial (CA) en la remoción del colorante reactivo Blue 39 (B39) en disolución acuosa a 25°C. Los datos experimentales del estudio en lote realizado a diferentes pH (6-8) y concentraciones iniciales de B39 (5-200 mg dm 3), se ajustan satisfactoriamente al modelo de isoterma de Freundlich, presentando una capacidad máxima de adsorción en monocapa de 17,7 mg g-1 a pH 8. El estudio dinámico a diferentes alturas del lecho (1, 3 y 5 cm), flujos volumétricos (1 y 5 cm3 min-1) y concentración inicial de 5,5 mg dm-3, muestra que el tiempo de servicio de la columna y la capacidad de remoción mejoran cuando la altura aumenta y el flujo volumétrico disminuye. El modelo del tiempo de servicio de la altura del lecho (BDST) se aplicó a los datos experimentales ajustándose de manera aceptable.Abstract: Dyes are usually present in water effluents of many industries, such as textiles, leather, paper, printing and cosmetics. The effectiveness of the adsorption of dyes in wastewater using inexpensive adsorbents has enabled the extension of this technique for removal, over other methods of treatment. This study investigated the adsorption capacity of a commercial activated carbon (AC) on the removal of reactive dye Blue 39 (B39) in water solution at 25°C. The experimental ,conform to the model of Freundlich isotherm, presenting a maximum adsorption capacity monolayer 17.7 mg g-1 at pH 8. The dynamic study at different heights of the bed (1, 3 and 5 cm), flow rates (1 and 5 cm3 min-1) and initial concentration of 5,5 mg dm-3, shows that the time service and the capacity column removal improved when the height increases and the flow rate decreases. The model of the service time of the bed height (BDST) was applied to the experimental data at an acceptable conform

Análise da composição química do óleo essencial de um poejo - Hesperozygis myrtoides coletado em Aiuruoca (MG).

O Parque Estadual Serra do Papagaio, criado em agosto de 1998, é um dos últimos remanescentes de Mata Atlântica do Estado de Minas Gerais englobando, entre outros municípios, Aiuruoca. Dentre as diversas espécies nativas utilizadas pela população local, destaca-se um pequeno arbusto aromático denominado na região como Poejo, por seu aroma peculiar de menta. A espécie, identificada como Hesperogygis myrtoides (St. Hill. ex Benth.) Epling, é utilizada medicinalmente na forma de chá e na elaboração de uma bebida artesanal. Segundo a tradição, partes aéreas da planta são mergulhadas em aguardente de cana e deixadas em infusão por um ano, durante o qual a garrafa deve ficar enterrada sob o solo até o momento do consumo. Com o objetivo de avaliar a composição química deste óleo essencial, a planta foi coletada a cerca de 1.800 m de altitude, durante o período de floração. O óleo essencial de folhas e flores foi obtido por hidrodestilação, por duas horas e analisado por CG-DIC, CG-EM e CGxCG bidimensional quiral