The Caenorhabditis elegans histone hairpin-binding protein is required for core histone gene expression and is essential for embryonic and postembryonic cell division.

As in all metazoans, the replication-dependent histone genes of Caenorhabditis elegans lack introns and contain a short hairpin structure in the 3' untranslated region. This hairpin structure is a key element for post-transcriptional regulation of histone gene expression and determines mRNA 3' end formation, nuclear export, translation and mRNA decay. All these steps contribute to the S-phase-specific expression of the replication-dependent histone genes. The hairpin structure is the binding site for histone hairpin-binding protein that is required for hairpin-dependent regulation. Here, we demonstrate that the C. elegans histone hairpin-binding protein gene is transcribed in dividing cells during embryogenesis and postembryonic development. Depletion of histone hairpin-binding protein (HBP) function in early embryos using RNA-mediated interference leads to an embryonic-lethal phenotype brought about by defects in chromosome condensation. A similar phenotype was obtained by depleting histones H3 and H4 in early embryos, indicating that the defects in hairpin-binding protein-depleted embryos are caused by reduced histone biosynthesis. We have confirmed this by showing that HBP depletion reduces histone gene expression. Depletion of HBP during postembryonic development also results in defects in cell division during late larval development. In addition, we have observed defects in the specification of vulval cell fate in animals depleted for histone H3 and H4, which indicates that histone proteins are required for cell fate regulation during vulval development.

Phyllotaxis involves auxin drainage through leaf primordia

The spatial arrangement of leaves and flowers around the stem, known as phyllotaxis, is controlled by an auxin-dependent reiterative mechanism that leads to regular spacing of the organs and thereby to remarkably precise phyllotactic patterns. The mechanism is based on the active cellular transport of the phytohormone auxin by cellular influx and efflux carriers, such as AUX1 and PIN1. Their important role in phyllotaxis is evident from mutant phenotypes, but their exact roles in space and time are difficult to address due to the strong pleiotropic phenotypes of most mutants in phyllotaxis. Models of phyllotaxis invoke the accumulation of auxin at leaf initials and removal of auxin through their developing vascular strand, the midvein. We have developed a precise microsurgical tool to ablate the midvein at high spatial and temporal resolution in order to test its function in leaf formation and phyllotaxis. Using amplified femtosecond laser pulses, we ablated the internal tissues in young leaf primordia of tomato (Solanum lycopersicum) without damaging the overlying L1 and L2 layers. Our results show that ablation of the future midvein leads to a transient accumulation of auxin in the primordia and to an increase in their width. Phyllotaxis was transiently affected after midvein ablations, but readjusted after two plastochrons. These results indicate that the developing midvein is involved in the basipetal transport of auxin through young primordia, which contributes to phyllotactic spacing and stability.

Drosophila valois encodes a divergent WD protein that is required for Vasa localization and Oskar protein accumulation

valois (vls) was identified as a posterior group gene in the initial screens for Drosophila maternal-effect lethal mutations. Despite its early genetic identification, it has not been characterized at the molecular level until now. We show that vls encodes a divergent WD domain protein and that the three available EMS-induced point mutations cause premature stop codons in the vls ORF. We have generated a null allele that has a stronger phenotype than the EMS mutants. The vlsnull mutant shows that vls+ is required for high levels of Oskar protein to accumulate during oogenesis, for normal posterior localization of Oskar in later stages of oogenesis and for posterior localization of the Vasa protein during the entire process of pole plasm assembly. There is no evidence for vls being dependent on an upstream factor of the posterior pathway, suggesting that Valois protein (Vls) instead acts as a co-factor in the process. Based on the structure of Vls, the function of similar proteins in different systems and our phenotypic analysis, it seems likely that vls may promote posterior patterning by facilitating interactions between different molecules.

Ephrin-B1 transduces signals to activate integrin-mediated migration, attachment and angiogenesis.

Ephrin-B/EphB family proteins are implicated in bidirectional signaling and were initially defined through the function of their ectodomain sequences in activating EphB receptor tyrosine kinases. Ephrin-B1-3 are transmembrane proteins sharing highly conserved C-terminal cytoplasmic sequences. Here we use a soluble EphB1 ectodomain fusion protein (EphB1/Fc) to demonstrate that ephrin-B1 transduces signals that regulate cell attachment and migration. EphB1/Fc induced endothelial ephrin-B1 tyrosine phosphorylation, migration and integrin-mediated (alpha(v)beta(3) and alpha(5)beta(1)) attachment and promoted neovascularization, in vivo, in a mouse corneal micropocket assay. Activation of ephrin-B1 by EphB1/Fc induced phosphorylation of p46 JNK but not ERK-1/2 or p38 MAPkinases. By contrast, mutant ephrin-B1s bearing either a cytoplasmic deletion (ephrin-B1DeltaCy) or a deletion of four C-terminal amino acids (ephrin-B1DeltaPDZbd) fail to activate p46 JNK. Transient expression of intact ephin-B1 conferred EphB1/Fc migration responses on CHO cells, whereas the ephrin-B1DeltaCy and ephrin-B1DeltaPDZbd mutants were inactive. Thus ephrin-B1 transduces 'outside-in' signals through C-terminal protein interactions that affect integrin-mediated attachment and migration.

Flagellar membranes are rich in raft-forming phospholipids.

The observation that the membranes of flagella are enriched in sterols and sphingolipids has led to the hypothesis that flagella might be enriched in raft-forming lipids. However, a detailed lipidomic analysis of flagellar membranes is not available. Novel protocols to detach and isolate intact flagella from Trypanosoma brucei procyclic forms in combination with reverse-phase liquid chromatography high-resolution tandem mass spectrometry allowed us to determine the phospholipid composition of flagellar membranes relative to whole cells. Our analyses revealed that phosphatidylethanolamine, phosphatidylserine, ceramide and the sphingolipids inositol phosphorylceramide and sphingomyelin are enriched in flagella relative to whole cells. In contrast, phosphatidylcholine and phosphatidylinositol are strongly depleted in flagella. Within individual glycerophospholipid classes, we observed a preference for ether-type over diacyl-type molecular species in membranes of flagella. Our study provides direct evidence for a preferential presence of raft-forming phospholipids in flagellar membranes of T. brucei.

TNF receptors regulate vascular homeostasis in zebrafish through a caspase-8, caspase-2 and P53 apoptotic program that bypasses caspase-3

Although it is known that tumor necrosis factor receptor (TNFR) signaling plays a crucial role in vascular integrity and homeostasis, the contribution of each receptor to these processes and the signaling pathway involved are still largely unknown. Here, we show that targeted gene knockdown of TNFRSF1B in zebrafish embryos results in the induction of a caspase-8, caspase-2 and P53-dependent apoptotic program in endothelial cells that bypasses caspase-3. Furthermore, the simultaneous depletion of TNFRSF1A or the activation of NF-κB rescue endothelial cell apoptosis, indicating that a signaling balance between both TNFRs is required for endothelial cell integrity. In endothelial cells, TNFRSF1A signals apoptosis through caspase-8, whereas TNFRSF1B signals survival via NF-κB. Similarly, TNFα promotes the apoptosis of human endothelial cells through TNFRSF1A and triggers caspase-2 and P53 activation. We have identified an evolutionarily conserved apoptotic pathway involved in vascular homeostasis that provides new therapeutic targets for the control of inflammation- and tumor-driven angiogenesis.

Spatio-temporal Rho GTPase signaling - where are we now?

Rho-family GTPases are molecular switches that transmit extracellular cues to intracellular signaling pathways. Their regulation is likely to be highly regulated in space and in time, but most of what is known about Rho-family GTPase signaling has been derived from techniques that do not resolve these dimensions. New imaging technologies now allow the visualization of Rho GTPase signaling with high spatio-temporal resolution. This has led to insights that significantly extend classic models and call for a novel conceptual framework. These approaches clearly show three things. First, Rho GTPase signaling dynamics occur on micrometer length scales and subminute timescales. Second, multiple subcellular pools of one given Rho GTPase can operate simultaneously in time and space to regulate a wide variety of morphogenetic events (e.g. leading-edge membrane protrusion, tail retraction, membrane ruffling). These different Rho GTPase subcellular pools might be described as 'spatio-temporal signaling modules' and might involve the specific interaction of one GTPase with different guanine nucleotide exchange factors (GEFs), GTPase-activating proteins (GAPs) and effectors. Third, complex spatio-temporal signaling programs that involve precise crosstalk between multiple Rho GTPase signaling modules regulate specific morphogenetic events. The next challenge is to decipher the molecular circuitry underlying this complex spatio-temporal modularity to produce integrated models of Rho GTPase signaling.

Na 1 Nachlass Max Horkheimer, 583 - Korrespondenzen mit Friedrich (Frederick) Pollock (p. VI 35, 128-314)

2 Briefe zwischen Frederick Pollock und der Southern Counties Gas Company of California (Santa Monica), Dezember 1946; 1 Brief von Frederick Pollock an Pacific Electric Railway Co. (West Los Angeles), 16.05.1946;

Atentique´s environmental and economic development shrinkage in globlalization era

This paper focuses on the effects the transfer of ownership from a state‐owned Paper Mill Company to a corporate private ownership has had on environmental and economic shrinkage in Atenquique. This transfer was the result of the ongoing economic process of globalization, after the industrial boom of the paper mills during the second half of the last century. The paper also focuses on how the employees of this Paper Mill Company live and how they have been affected by globalization and how they feel about their paper mill’s new corporate owners. The methodology used was descriptive and exploratory. A sample of ten workers at the company who lived in Atenquique was chosen for an interview. After being inhabited the town of Atenquique developed in terms of population, society and economy. On the other hand the Industrial Company of Atenquique grew during the period when it was a property of the Mexican State. After the company’s privatization, the town started to decline and shrink in three above‐mentioned variables. The impact on the environmental and economic development has initiated the shrinking and declining of Atenquique and the surrounding cities and towns.

Impacto gerado na vida das mulheres removidas das favelas

Interventions that seek to change the areas occupied by squatters have been one of the most common forms of Urban Management Policies, trying revolver one of the major problems of Brazilian metropolises, namely the precarious living conditions of a large part of the population in the city. A Pedreira Prado Lopes, a slum located in the northwestern region of Belo Horizonte, is one of twelve local benefit program by urbanization of slums Vila Viva, a program of structural intervention in Slums at the municipal level. These interventions, which are benefiting 9,000 residents have funds of R$37,4 millions the PAC (Growth Acceleration Program) and were guided by PGE - Specific Global Plan prepared by technicians URBEL (Urbanization Company of Belo Horizonte) in 1998. This project intervention was the creation of a set of housing for former slum housing. The objective of this research is to know how this intervention impacted the lives of residents after settling in condominiums, seeking to describe the changes on the horizon of women who are in most household heads residents of these buildings, as shown by studies of the IBGE (Brazilian Institute of Geography and Statistics), 2011

Lucha obrera, conflicto sindical y organización armada : El caso de la Juventud Trabajadora Peronista de Propulsora Siderúrgica [1973-1976]

El presente trabajo aborda el caso de la Juventud Trabajadora Peronista en la empresa Propulsora Siderúrgica de la localidad de Ensenada en el período 1973-1976, constituyendo éste un período clave en la historia política argentina en tanto significó el retorno del peronismo al poder luego de dieciocho años de proscripción legal. Enmarcada en la extensa constelación de experiencias de la ?nueva izquierda? que irrumpe con fuerza en Argentina a partir de fines de los años sesenta, y específicamente en la amplia experiencia de las fuerzas peronistas revolucionarias dentro de ella, la Juventud Trabajadora Peronista aparece como un espacio político-sindical especialmente rico para el estudio y análisis en el campo de la historia reciente argentina y dentro de ella de las prácticas sindicales radicalizadas. Fundada en 1973, la JTP nace como frente de masas sindical de la organización armada Montoneros. Fundada en el contexto histórico, político y social de retorno de Perón al país y de crisis del gobierno peronista, ésta seráparte de la emergencia de particulares formas de vínculo social en el que se entrecruzan elementos ligados a la práctica de los militantes obreros, sus agrupaciones sindicales, el proceso de radicalización general del período y la singular participación de las organizaciones armadas peronistas. Contemplado el entrecruzamiento entre organizaciones armadas revolucionarias, organizaciones sindicales combativas y la radicalización de sectores de la clase trabajadora, nuestro trabajo enfatiza la capacidad política obrera para imponer condiciones al capital, al gobierno y a sectores burocráticos del sindicalismo. Es en estos tres frentes de combate en los que se verán inmersos los sectores radicalizados de la clase obrera argentina que buscamos poner en un primer plano a lo largo de esta investigación

Estado y cooperativismo eléctrico. El caso de la provincia de Córdoba, 1958-1966

En este artículo, que es parte de una investigación mayor dedicada al estudio del desarrollo eléctrico de la provincia de Córdoba entre 1958 y 1966(1), se analiza el papel jugado por el cooperativismo en el proceso de electrificación y los resultados de la política estatal de fomento de ese tipo de instituciones. La encargada de implementar esa política, por expresa delegación del Estado local, fue la Empresa Provincial de Energía de Córdoba (EPEC); es por ello que la misma, ocupa un lugar destacado en la instalación y desarrollo de estas entidades. En las fuentes consultadas, especialmente las memorias y balances de la organización pública, anteriormente nombrada, hemos encontrado información detallada sobre la ayuda financiera y los préstamos de equipos realizados a las cooperativas, tendientes a favorecer la expansión del servicio a las zonas rurales adyacentes a las localidades en las que estaban radicadas; como así también respecto del desarrollo de la infraestructura eléctrica provincial a través de la cual, las asociaciones distribuirían el fluido.

Lucha obrera, conflicto sindical y organización armada : El caso de la Juventud Trabajadora Peronista de Propulsora Siderúrgica [1973-1976]

El presente trabajo aborda el caso de la Juventud Trabajadora Peronista en la empresa Propulsora Siderúrgica de la localidad de Ensenada en el período 1973-1976, constituyendo éste un período clave en la historia política argentina en tanto significó el retorno del peronismo al poder luego de dieciocho años de proscripción legal. Enmarcada en la extensa constelación de experiencias de la ?nueva izquierda? que irrumpe con fuerza en Argentina a partir de fines de los años sesenta, y específicamente en la amplia experiencia de las fuerzas peronistas revolucionarias dentro de ella, la Juventud Trabajadora Peronista aparece como un espacio político-sindical especialmente rico para el estudio y análisis en el campo de la historia reciente argentina y dentro de ella de las prácticas sindicales radicalizadas. Fundada en 1973, la JTP nace como frente de masas sindical de la organización armada Montoneros. Fundada en el contexto histórico, político y social de retorno de Perón al país y de crisis del gobierno peronista, ésta seráparte de la emergencia de particulares formas de vínculo social en el que se entrecruzan elementos ligados a la práctica de los militantes obreros, sus agrupaciones sindicales, el proceso de radicalización general del período y la singular participación de las organizaciones armadas peronistas. Contemplado el entrecruzamiento entre organizaciones armadas revolucionarias, organizaciones sindicales combativas y la radicalización de sectores de la clase trabajadora, nuestro trabajo enfatiza la capacidad política obrera para imponer condiciones al capital, al gobierno y a sectores burocráticos del sindicalismo. Es en estos tres frentes de combate en los que se verán inmersos los sectores radicalizados de la clase obrera argentina que buscamos poner en un primer plano a lo largo de esta investigación