Voting in the Bicameral Congress: Large Majorities as a Signal of Quality

We estimate a model of voting in Congress that allows for dispersed information about the quality of proposals in an equilibrium context. The results highlight the effects of bicameralism on policy outcomes. In equilibrium, the Senate imposes an endogenous supermajority rule on members of the House. We estimate this super- majority rule to be about four-fifths on average across policy areas. Moreover, our results indicate that the value of the information dispersed among legislators is significant, and that in equilibrium a large fraction of House members (40-50 %) vote in accordance with their private information. Taken together, our results imply a highly conservative Senate, in the sense that proposals are enacted into law only when it is extremely likely that their quality is high

Comentarios sobre las posibilidades de un nuevo programa macroeconómico entre Honduras y el Fondo Monetario Internacional

El presente informe analiza de manera sucinta las ponencias efectuadas tanto por las autoridades del gobierno de Honduras como por el representante del Fondo Monetario Internacional (FMI) en la reunión mantenida por ambas partes el 24 de abril de 2007 en Tegucigalpa. En la exposición se han tomado en cuenta, asimismo, las conversaciones previas mantenidas por el consultor con las autoridades del gobierno en la misión de apoyo realizada en los últimos días de febrero de 2007, así como algunos análisis cuantitativos llevados a cabo en el marco de consistencia elaborado, en la órbita de dicha misión, a pedido de las autoridades.

The Not-So-Popular Branch: Bicameralism as a Counter-Majoritarian Device

We estimate a model of voting in Congress that allows for dispersed information about the quality of proposals in an equilibrium context. The results highlight the effects of bicameralism on policy outcomes. In equilibrium, the Senate imposes an endogenous supermajority rule on members of the House. We estimate this supermajority rule to be about four-fifths on average across policy areas. Moreover, our results indicate that the value of the information dispersed among legislators is significant, and that in equilibrium a large fraction of House members (40-50%) vote in accordance with their private information. Taken together, our results imply a highly conservative Senate, in the sense that proposals are enacted into law only when it is extremely likely that their quality is high

Editorial: Microbial Regulation of Translation

Since the description of the operon model by Jacob and Monod during the late 1950s and early 1960s (Ullmann, 2010), the concept that the reading of genetic information must be a regulated process has been central to our understanding of biology. This is particularly true for microbes, which can adapt to an incredible variety of environments. Based on the research performed since the description of the operon, we have gained a deep understanding of the diverse strategies used by microbes to modulate the transcription of genetic information from DNA to RNA. In contrast, the mechanisms that regulate the translation of messenger RNAs into proteins has received less attention. The technical developments of the last decade now allow us to obtain detailed information on RNA folding (Rouskin et al., 2014; Aw et al., 2016) and modification (Linder et al., 2015; Lorenz et al., 2020) and the speed of translation (Subramaniam et al., 2013; Ingolia, 2014; Dai et al., 2016). This, in turn, allows us to scrutinize the functionality of translation components in vivo, providing unprecedented opportunities to study translation regulation. In this special issue of Frontiers in Genetics, \u27Microbial Regulation of Translation,\u27 we have assembled a series of articles that use diverse experimental approaches to study the regulation of translation in microbes

Enhanced phosphatidylinositol 3-kinase (PI3K)/Akt signaling has pleiotropic targets in hippocampal neurons exposed to iron-induced oxidative stress

The phosphatidylinositol 3-kinase (PI3K)/Akt pathway is a key component in synaptic plasticity and neuronal survival. The aim of this work was to investigate the participation of the PI3K/Akt pathway and its outcome on different molecular targets such as glycogen synthase kinase 3β (GSK3β) and Forkhead box-O (FoxO) transcription factors during mild oxidative stress triggered by iron overload. The exposure of mouse hippocampal neurons (HT22) to different concentrations of Fe 2+ (25-200 μM) for 24 h led us to define a mild oxidative injury status (50 μM Fe 2+ ) in which cell morphology showed changes typical of neuronal damage, with increased lipid peroxidation and cellular oxidant levels but no alteration of cellular viability. There was a simultaneous increase in both Akt and GSK3β phosphorylation. Levels of phospho-FoxO3a (inactive form) increased in the cytosolic fraction of cells treated with iron in a PI3K-dependent manner. Moreover, PI3K and Akt translocated to the nucleus in response to oxidative stress. Iron-overloaded cells harboring a constitutively active form of Akt showed decreased oxidants levels. Indeed, glutathione (GSH) synthesis under oxidative stress conditions was regulated by activated Akt. Our results show that activation of the PI3K/Akt pathway during iron-induced neurotoxicity regulates multiple targets such as GSK3β, FoxO transcriptional activity and glutathione metabolism thus modulating neuronal response to oxidative stress.Fil: Uranga, Romina Maria. Universidad Nacional del Sur; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico CONICET Bahía Blanca. Instituto de Investigaciones Bioquímicas Bahía Blanca (i); ArgentinaFil: Katz, Sebastian. Universidad Nacional del Sur; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico CONICET Bahía Blanca. Instituto de Investigaciones Bioquímicas Bahía Blanca (i); ArgentinaFil: Salvador, Gabriela Alejandra. Universidad Nacional del Sur; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico CONICET Bahía Blanca. Instituto de Investigaciones Bioquímicas Bahía Blanca (i); Argentin

El tipo de cambio como amortiguador y amplificador de shocks: Un análisis de los canales de trasmisión y la caja de herramientas de política en economías pequeñas y abiertas

¿Cuáles son los regímenes de política y la combinación de instrumentos más adecuados en economías pequeñas y abiertas para hacer frente a la volatilidad de los flujos de capitales y a la influencia del ciclo financiero global? En este trabajo se revisa la experiencia reciente de varias economías emergentes y se repasan los argumentos en favor del uso de diversas herramientas y enfoques de política, de naturaleza convencional y no convencional. En particular, se examinan las distintas razones que pueden impedir que la flexibilidad cambiaria plena permita la absorción de shocks. Ello demanda en muchas circunstancias la utilización de herramientas alternativas (que a veces sustituyen pero que en otros casos mayormente complementan) a la flexibilidad cambiaria: intervenciones en los mercados de cambios, regulaciones macroprudenciales y controles a la movilidad plena de capitales. Nuestra principal contribución no consiste en la discusión de nuevos canales de transmisión del tipo de cambio al desempeño macro/financiero, sino en la presentación de los canales identificados por una amplia literatura de manera sistemática y ordenada. Lo mismo ocurre con el conjunto de herramientas actualmente utilizadas por muchos Bancos Centrales para hacer frente a la ocurrencia de perturbaciones. Se concluye que las respuestas de política más apropiadas dependen críticamente, no sólo de la naturaleza y la intensidad de los shocks a los que dichas economías están típicamente expuestas, sino también de los rasgos estructurales y de las condiciones y circunstancias particulares que cada una de ellas exhibe en el “punto de partida”.Fil: Dvoskin, Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Martín; Argentina. Banco Central de la República Argentina; ArgentinaFil: Katz, Sebastian. Banco Central de la República Argentina; Argentin

Activation of the PI3K/Akt signaling pathway through P2Y2 receptors by extracellular ATP is involved in osteoblastic cell proliferation

We studied the PI3K/Akt signaling pathway modulation and its involvement in the stimulation of ROS 17/2.8 osteoblast-like cell proliferation by extracellular ATP. A dose- and time-dependent increase in Akt-Ser 473 phosphorylation (p-Akt) was observed. p-Akt was increased by ATPγS and UTP, but not by ADPβS. Akt activation was abolished by PI3K inhibitors and reduced by inhibitors of PI-PLC, Src, calmodulin (CaM) but not of CaMK. p-Akt was diminished by cell incubation in a Ca2+-free medium but not by the use of L-type calcium channel blockers. The rise in intracellular Ca 2+ induced by ATP was potentiated in the presence of Ro318220, a PKC inhibitor, and attenuated by the TPA, a known activator of PKC. ATP-dependent p-Akt was diminished by TPA and augmented by Ro318220 treatment in a Ca 2+-containing but not in a Ca2+-free medium. ATP stimulated the proliferation of both ROS 17/2.8 cells and rat osteoblasts through PI3K/Akt. In the primary osteoblasts, ATP induces alkaline phosphatase activity via PI3K, suggesting that the nucleotide promotes osteoblast differentiation. These results suggest that ATP stimulates osteoblast proliferation through PI-PLC linked-P2Y2 receptors and PI3K/Akt pathway activation involving Ca2+, CaM and Src. PKC seems to regulate Akt activation through Src and the Ca2+ influx/CaM pathway.Fil: Katz, Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; ArgentinaFil: Ayala Peña, Victoria Belen. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; ArgentinaFil: Santillán, Graciela Edith. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; ArgentinaFil: Boland, Ricardo Leopoldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; Argentin

Oxidative stress strongly restricts the effect of codon choice on the efficiency of protein synthesis in Escherichia coli.

INTRODUCTION The response of enterobacteria to oxidative stress is usually considered to be regulated by transcription factors such as OxyR and SoxR. Nevertheless, several reports have shown that under oxidative stress the levels, modification and aminoacylation of tRNAs may be altered suggesting a role of codon bias in regulation of gene expression under this condition. METHODS In order to characterize the effects of oxidative stress on translation elongation we constructed a library of 61 plasmids, each coding for the green fluorescent protein (GFP) translationally fused to a different set of four identical codons. RESULTS Using these reporters, we observed that GFP production levels vary widely (~15 fold) when Escherichia coli K-12 is cultured in minimal media as a consequence of codon choice variations. When bacteria are cultured under oxidative stress caused by paraquat the levels of GFP produced by most clones is reduced and, in contrast to control conditions, the range of GFP levels is restricted to a ~2 fold range. Restricting elongation of particular sequences does not increase the range of GFP production under oxidative stress, but altering translation initiation rates leads to an increase in this range. DISCUSSION Altogether, our results suggest that under normal conditions the speed of translation elongation is in the range of the speed of initiation and, consequently, codon choice impacts the speed of protein synthesis. In contrast, under oxidative stress translation initiation becomes much slower than elongation, limiting the speed of translation such that codon choice has at most only subtle effects on the overall output of translation

Oxidative Stress Strongly Restricts the Effect of Codon Choice on the Efficiency of Protein Synthesis in \u3cem\u3eEscherichia coli\u3c/em\u3e

Introduction The response of enterobacteria to oxidative stress is usually considered to be regulated by transcription factors such as OxyR and SoxR. Nevertheless, several reports have shown that under oxidative stress the levels, modification and aminoacylation of tRNAs may be altered suggesting a role of codon bias in regulation of gene expression under this condition. Methods In order to characterize the effects of oxidative stress on translation elongation we constructed a library of 61 plasmids, each coding for the green fluorescent protein (GFP) translationally fused to a different set of four identical codons. Results Using these reporters, we observed that GFP production levels vary widely (~15 fold) when Escherichia coli K-12 is cultured in minimal media as a consequence of codon choice variations. When bacteria are cultured under oxidative stress caused by paraquat the levels of GFP produced by most clones is reduced and, in contrast to control conditions, the range of GFP levels is restricted to a ~2 fold range. Restricting elongation of particular sequences does not increase the range of GFP production under oxidative stress, but altering translation initiation rates leads to an increase in this range. Discussion Altogether, our results suggest that under normal conditions the speed of translation elongation is in the range of the speed of initiation and, consequently, codon choice impacts the speed of protein synthesis. In contrast, under oxidative stress translation initiation becomes much slower than elongation, limiting the speed of translation such that codon choice has at most only subtle effects on the overall output of translation

Universal Dependencies for Learner English

We introduce the Treebank of Learner English (TLE), the first publicly available syntactic treebank for English as a Second Language (ESL). The TLE provides manually annotated POS tags and Universal Dependency (UD) trees for 5,124 sentences from the Cambridge First Certificate in English (FCE) corpus. The UD annotations are tied to a pre-existing error annotation of the FCE, whereby full syntactic analyses are provided for both the original and error corrected versions of each sentence. Further on, we delineate ESL annotation guidelines that allow for consistent syntactic treatment of ungrammatical English. Finally, we benchmark POS tagging and dependency parsing performance on the TLE dataset and measure the effect of grammatical errors on parsing accuracy. We envision the treebank to support a wide range of linguistic and computational research o n second language acquisition as well as automatic processing of ungrammatical language.This work was supported by the Center for Brains, Minds and Machines (CBMM), funded by NSF STC award CCF – 1231216