Ethylene-Mediated Phospholipid Catabolic Pathway in Glucose-Starved Carrot Suspension Cells1

Glucose (Glc) starvation of suspension-cultured carrot (Daucus carota L.) cells resulted in sequential activation of phospholipid catabolic enzymes. Among the assayed enzymes involved in the degradation, phospholipase D (PLD) and lipolytic acyl hydrolase were activated at the early part of starvation, and these activities were followed by β-oxidation and the glyoxylate cycle enzymes in order. The activity of PLD and lipolytic acyl hydrolase was further confirmed by in vivo-labeling experiments. It was demonstrated that Glc added to a medium containing starving cells inhibited the phospholipid catabolic activities, indicating that phospholipid catabolism is negatively regulated by Glc. There was a burst of ethylene production 6 h after starvation. Ethylene added exogeneously to a Glc-sufficient medium activated PLD, indicating that ethylene acts as an element in the signal transduction pathway leading from Glc depletion to PLD activation. Activation of lipid peroxidation, suggestive of cell death, occurred immediately after the decrease of the phospholipid degradation, suggesting that the observed phospholipid catabolic pathway is part of the metabolic strategies by which cells effectively survive under Glc starvation.

Characterization of the promoter region of the mouse Xist gene.

The mouse Xist gene is expressed exclusively from the inactive X chromosome and may be implicated in initiating X inactivation. To better understand the mechanisms underlying the control of Xist expression, we investigated the upstream regulatory region of the mouse Xist promoter. A 1.2-kb upstream region of the Xist gene was sequenced and promoter activity was studied by chloramphenicol acetyltransferase (CAT) assays after transfection in murine XX and XY cell lines. The region analyzed (-1157 to +917 showed no in vitro sex-specific promoter activity. However, a minimal constitutional promoter was assigned to a region from -81 to +1, and a cis element from -41 to -15 regulates promoter activity. We showed that a nuclear factor binds to an element located at -30 to -25 (TTAAAG). A second sequence at -41 to -15 does not act as an enhancer and is unable to confer transcriptional activity to the Xist gene on its own. A third region from -82 to -41 is needed for correct expression. Deletion of the segment -441 to -231 is associated with an increase in CAT activity and may represent a silencer element.

Inhibition of NF-AT-dependent transcription by NF-kappa B: implications for differential gene expression in T helper cell subsets.

Activation of individual CD4+ T cells results in differential lymphokine expression: interleukin 2 (IL-2) is preferentially produced by T helper type 1 (TH1) cells, which are involved in cell-mediated immune responses, whereas IL-4 is synthesized by TH2 cells, which are essential for humoral immunity. The Ca(2+)-dependent factor NF-ATp plays a key role in the inducible transcription of both these lymphokine genes. However, while IL2 expression requires the contribution of Ca(2+)- and protein kinase C-dependent signals, we report that activation of human IL4 transcription through the Ca(2+)-dependent pathway is diminished by protein kinase C stimulation in Jurkat T cells. This phenomenon is due to mutually exclusive binding of NF-ATp and NF-kappa B to the P sequence, an element located 69 bp upstream of the IL4 transcription initiation site. Human IL4 promoter-mediated transcription is downregulated in Jurkat cells stimulated with the NF-kappa B-activating cytokine tumor necrosis factor alpha and suppressed in RelA-overexpressing cells. In contrast, protein kinase C stimulation or RelA overexpression does not affect the activity of a human IL4 promoter containing a mouse P sequence, which is a higher-affinity site for NF-ATp and a lower-affinity site for RelA. Thus, competition between two general transcriptional activators, RelA and NF-ATp, mediates the inhibitory effect of protein kinase C stimulation on IL4 expression and may contribute to differential gene expression in TH cells.

Mutation of conserved negatively charged residues in the S2 and S3 transmembrane segments of a mammalian K+ channel selectively modulates channel gating.

Voltage-gated channel proteins sense a change in the transmembrane electric field and respond with a conformational change that allows ions to diffuse across the pore-forming structure. Site-specific mutagenesis combined with electrophysiological analysis of expressed mutants in amphibian oocytes has previously established the S4 transmembrane segment as an element of the voltage sensor. Here, we show that mutations of conserved negatively charged residues in S2 and S3 of a brain K+ channel, thought of as countercharges for the positively charged residues in S4, selectively modulate channel gating without modifying the permeation properties. Mutations of Glu235 in S2 that neutralize or reverse charge increase the probability of channel opening and the apparent gating valence. In contrast, replacements of Glu272 by Arg or Thr268 by Asp in S3 decrease the open probability and the apparent gating valence. Residue Glu225 in S2 tolerated replacement only by acidic residues, whereas Asp258 in S3 was intolerant to any attempted change. These results imply that S2 and S3 are unlikely to be involved in channel lining, yet, together with S4, may be additional components of the voltage-sensing structure.

Specific binding of RNA polymerase II to the human immunodeficiency virus trans-activating region RNA is regulated by cellular cofactors and Tat.

The regulation of human immunodeficiency virus type 1 (HIV-1) gene expression in response to Tat is dependent on an element downstream of the HIV-1 transcriptional initiation site designated the trans-activating region (TAR). TAR forms a stable stem-loop RNA structure in which a 3-nt bulge structure and a 6-nt loop structure are important for Tat activation. In the absence of Tat, the HIV-1 promoter generates so-called short or nonprocessive transcripts terminating at +60, while in the presence of Tat the synthesis of these short transcripts is markedly decreased and transcripts that extend through the 9.0-kb HIV-1 genome are synthesized. Tat effects on transcriptional elongation are likely due to alterations in the elongation properties of RNA polymerase II. In this study we demonstrated that a set of cellular cofactors that modulate the binding of the cellular protein TRP-185 to the TAR RNA loop sequences also functioned to markedly stimulate the specific binding of hypophosphorylated (IIa) and hyperphosphorylated (IIo) RNA polymerase II to TAR RNA. The concentrations of RNA polymerase II required for this interaction with TAR RNA were similar to those required to initiate in vitro transcription from the HIV-1 long terminal repeat. RNA gel retardation analysis with wild-type and mutant TAR RNAs indicated that the TAR RNA loop and bulge sequences were critical for the binding of RNA polymerase II. The addition of wild-type but not mutant Tat protein to gel retardation analysis with TAR RNA and RNA polymerase II resulted in the loss of binding of RNA polymerase II binding to TAR RNA. These results suggest that Tat may function to alter RNA polymerase II, which is paused due to its binding to HIV-1 TAR RNA with resultant stimulation of its transcriptional elongation properties.

Pax5 (BSAP) regulates the murine immunoglobulin 3' alpha enhancer by suppressing binding of NF-alpha P, a protein that controls heavy chain transcription.

The Pax5 transcription factor BSAP (B-cell-specific activator protein) is known to bind to and repress the activity of the immunoglobulin heavy chain 3' alpha enhancer. We have detected an element--designated alpha P--that lies approximately 50 bp downstream of the BSAP binding site 1 and is required for maximal enhancer activity. In vitro binding experiments suggest that the 40-kDa protein that binds to this element (NF-alpha P) is a member of the Ets family present in both B-cell and plasma-cell nuclei. However, in vivo footprint analysis suggests that the alpha P site is occupied only in plasma cells, whereas the BSAP site is occupied in B cells but not in plasma cells. When Pax5 binding to the enhancer in B cells was blocked in vivo by transfection with a triple-helix-forming oligonucleotide an alpha P footprint appeared and endogenous immunoglobulin heavy chain transcripts increased. The triple-helix-forming oligonucleotide also increased enhancer activity of a transfected construct in B cells, but only when the alpha P site was intact. Pax5 thus regulates the 3' alpha enhancer and immunoglobulin gene transcription by blocking activation by NF-alpha P.

A dominant-negative mutant of human poly(ADP-ribose) polymerase affects cell recovery, apoptosis, and sister chromatid exchange following DNA damage.

Poly(ADP-ribose) polymerase [PARP; NAD+ ADP-ribosyltransferase; NAD+:poly(adenosine-diphosphate-D-ribosyl)-acceptor ADP-D-ribosyltransferase, EC 2.4.2.30] is a zinc-dependent eukaryotic DNA-binding protein that specifically recognizes DNA strand breaks produced by various genotoxic agents. To study the biological function of this enzyme, we have established stable HeLa cell lines that constitutively produce the 46-kDa DNA-binding domain of human PARP (PARP-DBD), leading to the trans-dominant inhibition of resident PARP activity. As a control, a cell line was constructed, producing a point-mutated version of the DBD, which has no affinity for DNA in vitro. Expression of the PARP-DBD had only a slight effect on undamaged cells but had drastic consequences for cells treated with genotoxic agents. Exposure of cell lines expressing the wild-type (wt) or the mutated PARP-DBD, with low doses of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) resulted in an increase in their doubling time, a G2 + M accumulation, and a marked reduction in cell survival. However, UVC irradiation had no preferential effect on the cell growth or viability of cell lines expressing the PARP-DBD. These PARP-DBD-expressing cells treated with MNNG presented the characteristic nucleosomal DNA ladder, one of the hallmarks of cell death by apoptosis. Moreover, these cells exhibited chromosomal instability as demonstrated by higher frequencies of both spontaneous and MNNG-induced sister chromatid exchanges. Surprisingly, the line producing the mutated DBD had the same behavior as those producing the wt DBD, indicating that the mechanism of action of the dominant-negative mutant involves more than its DNA-binding function. Altogether, these results strongly suggest that PARP is an element of the G2 checkpoint in mammalian cells.

Controle operário como direito

O controle operário é um fenômeno social, expressão direta da luta de classes e produto de um momento histórico no qual as relações sociais de produção são marcadas pela subsunção forma e real do trabalho ao capital e pela propriedade privada dos meios de produção. Nesse sentido, o controle operário se expressa em diversos momentos dessa histórica, seja como luta dos trabalhadores pela sobrevivência, de forma a garantir o emprego e sua fonte de subsistência, ou, luta revolucionária, para a superação do modo de produção capitalista, almejando não só o controle no local de trabalho, mas do próprio Estado. Quando se está falando de uma fábrica ou empresa, o método geralmente utilizado para se alcançar este objetivo é a ocupação do estabelecimento e o controle do processo produtivo, mas é possível que seu controle possa ser exercido por meio de conselhos no interior da fábrica, respaldado por uma organização operária e popular mais geral na sociedade. Esse fenômeno normalmente é abordado na sociologia ou na política, de forma a verificar as relações e contradições do controle operário com o modo de produção vigente e com as instituições políticas como Estado, o partido ou o Sindicato. Cumpre no presente trabalho, todavia, abordar em que medida o controle operário pode ser encarado como um direito dos trabalhadores de assumirem o controle do processo produtivo no local de trabalho. A partir de uma abordagem histórica do fenômeno do controle operário e de sua expressão contemporânea, como produto de ocupações de fábricas falidas ou em dificuldades financeiras, nas quais o empregador passa a descumprir reiteradamente os direitos trabalhistas, verifica-se que, ao contrário de uma violação ao direito de propriedade ou direito de posse, o que se configura, nessas hipóteses, é um verdadeiro direito dos trabalhadores de controlar a produção, notadamente com o intuito de manter a unidade produtiva e a geração de emprego e renda para a sociedade. Nesse sentido, devem ser protegidos juridicamente os métodos da classe trabalhadora que se efetivam com este fim, como as greves de ocupações ativas, quando conferem à posse ou à propriedade sua função social. Todavia, este direito não surge livre de contradições. Com efeito, o direito reproduziria em si a lógica capitalista, ou poderia servir de instrumento para a classe trabalhadora? Embora encaremos a forma jurídica enquanto produto da forma mercantil e, portanto, essencialmente capitalista, verificamos que o próprio desenvolvimento dialético da história não se dá livre de contradições. A nova racionalidade do direito social, nesse sentido, seria um elemento que, se por um lado busca reafirmar a lógica capitalista em seu bojo, restabelecendo os padrões de igualdade e liberdade, por outro carrega consigo elementos que, em alguma medida, expõe as contradições e os limites do próprio direito. Portanto, o direito ao controle operário não se mostra elemento prejudicial à classe trabalhadora, embora seja acompanhado de contradições inerentes.

Uzbekistán: la configuración de un nuevo estado. Especial referencia al estatus de la mujer

Uzbekistan has a long and interesting heritage of ancient civilization linked to the historic “Silk Road”, through which transited people, goods, ideas and cultures. The major cities of the Silk Road - Samarkand, Bukhara, and Khiva are testimonies of the past and leave a deep impression on any visitor. As time goes by, Uzbekistan has become a key country in the whole Central Asian region, because it possesses mineral, agricultural and natural resources and has a huge potential for development. It is rich in energy resources such as oil and gas, but it is very difficult to commercialize them due to its landlocked position. The historical legacy of the Republic of Uzbekistan is a valuable heritage. The above mentioned ancient cities used to be centers of science and art, where important architects created palaces, mosques, madrassas, minarets, and mausoleums of the Islamic style, that still exist today. This cultural wealth is an element of internal cohesion and external outreach towards Islamic heritage, related to such Muslim countries as Turkey and the Gulf States. Moreover, this historical and architectural heritage has enormous economic potential for tourism, which can contribute to strengthen the relations of cooperation and friendship between Uzbekistan and the International Society. The influence of tradition and culture has still a huge impact on the society. This can be felt for example, in the traditional gender roles distribution. As a result of which, meńs presence in the areas of decision making is still slightly higher than womeńs one...

α-sarcin and RNase T1 based immunoconjugates: the role of intracellular trafficking in cytotoxic efficiency

Toxins have been thoroughly studied for their use as therapeutic agents in search of an improvement in toxic efficiency together with a minimization of their undesired side effects. Different studies have shown how toxins can follow different intracellular pathways which are connected with their cytotoxic action inside the cells. The work herein presented describes the different pathways followed by the ribotoxin a-sarcin and the fungal RNase T1,as toxic domains of immunoconjugates with identical binding domain, the single chain variable fragment of a monoclonal antibody raised against the glycoprotein A33. According to the results obtained both immunoconjugates enter the cells via early endosomes and, while a-sarcin can translocate directly into the cytosol to exert its deathly action, RNase T1 follows a pathway that involves lysosomes and the Golgi apparatus. These facts contribute to explaining the different cytotoxicity observed against their targeted cells, and reveal how the innate properties of the toxic domain, apart from its catalytic features, can be a key factor to be considered for immunotoxin optimization.

Etnocentrismo, xenofobia y migraciones internacionales en una perspectiva comparada

Mediante un análisis comparado de 15 países, tanto desarrollados como en vías de desarrollo y empleando encuestas de opinión pública, se contrastan varias hipótesis relacionales entre etnocentrismo y xenofobia. Los resultados establecen al etnocentrismo como un elemento común a las sociedades analizadas, de forma que los núcleos de opinión etnocéntrica se encuentran tanto en los países emisores de emigración como en las sociedades receptoras. Asimismo, se comprueba la estrecha vinculación entre etnocentrismo y xenofobia, así como que en las sociedades con mayor grado de multiculturalidad de origen inmigratorio son más probables las actitudes xenófobas de origen etnocéntrico. Las conclusiones señalan que esta xenofobia, si bien se activa contextualmente (experiencia de inmigración multicultural), tiene sus raíces emocionales en los prejuicios etnocéntricos, indistintamente de posibles experiencias negativas con los inmigrantes.

Avenidas fluviales e inundaciones de los ríos Vinalopó y Segura en época islámica y sus consecuencias en el poblamiento

Son escasas las noticias de época andalusí sobre inundaciones fluviales en el sur de la provincia de Alicante. En la descripción de Elche del Mugrib de Ibn Sa’īd se nos informa indirectamente de una inundación del Vinalopó en el segundo cuarto del s. XIII; como consecuencia, la ciudad musulmana se anegó y bastante población la abandonó. Respecto al vecino río Segura, el geógrafo al-‘Udrī (m. 1085) al describimos el curso del río nos informa que su sistema de riegos es como el del Nilo; este paralelo se debe al uso inteligente que hacían los egipcios y los habitantes de la Vega Baja de las aguas de la inundación fluvial como abono periódico de sus tierras y como elemento para luchar contra los marjales. También se analizan otras noticias sobre la torre de Embergoñes, la cual, situada a la entrada del curso fluvial en Orihuela, consideramos que era un promontorio de señales y de vigilancia de la inundación. Finalmente se recuerda la existencia de acanaladuras en las puertas de la catedral de Orihuela para proteger el interior del templo de las aguas de avenida.

Topological structures of complex belief systems

The concepts of substantive beliefs and derived beliefs are defined, a set of substantive beliefs S like open set and the neighborhood of an element substantive belief. A semantic operation of conjunction is defined with a structure of an Abelian group. Mathematical structures exist such as poset beliefs and join-semilattttice beliefs. A metric space of beliefs and the distance of belief depending on the believer are defined. The concepts of closed and opened ball are defined. S′ is defined as subgroup of the metric space of beliefs Σ and S′ is a totally limited set. The term s is defined (substantive belief) in terms of closing of S′. It is deduced that Σ is paracompact due to Stone's Theorem. The pseudometric space of beliefs is defined to show how the metric of the nonbelieving subject has a topological space like a nonmaterial abstract ideal space formed in the mind of the believing subject, fulfilling the conditions of Kuratowski axioms of closure. To establish patterns of materialization of beliefs we are going to consider that these have defined mathematical structures. This will allow us to understand better cultural processes of text, architecture, norms, and education that are forms or the materialization of an ideology. This materialization is the conversion by means of certain mathematical correspondences, of an abstract set whose elements are beliefs or ideas, in an impure set whose elements are material or energetic. Text is a materialization of ideology.

Topological structures of complex belief systems (II): Textual materialization

Mythical and religious belief systems in a social context can be regarded as a conglomeration of sacrosanct rites, which revolve around substantive values that involve an element of faith. Moreover, we can conclude that ideologies, myths and beliefs can all be analyzed in terms of systems within a cultural context. The significance of being able to define ideologies, myths and beliefs as systems is that they can figure in cultural explanations. This, in turn, means that such systems can figure in logic-mathematical analyses.

Una propuesta fallida para propagar la vacuna contra la viruela en Hispanoamérica (1802)

Tras la inicial propagación del método jenneriano por Inglaterra y el resto del continente europeo, se mostró un gran interés por difundirlo hacia Oriente y América. En el caso de España, los focos epidémicos que estaban ocurriendo en los territorios de ultramar movieron a las autoridades de los distintos virreinatos a solicitar a la Corona que enviara cuanto antes el nuevo remedio. La monarquía borbónica, que había introducido las expediciones científicas como elemento de progreso y dominio, aprobó el proyecto conocido como “Real Expedición Filantrópica de la Vacuna”, que partió hacia América al mando de Balmis en 1803. Relatamos una propuesta inédita anterior a esa, en la que un desconocido cirujano, Rafael de Malaguilla, se ofreció para llevar a cabo una iniciativa similar.