Madrid 1919, un nuevo escenario urbano subterráneo: el Metro. Aparición en España del concepto de viaje sin referencias espaciales.

Esta comunicación recibió la condición especial de ser destacada por el Comité Científico. A comienzos del siglo XX se empieza a implantar un novedoso medio de transporte en las grandes ciudades españolas: el metro. Aunque ya se había probado con éxito en otras ciudades europeas (Londres, Viena, París?), la expectación surgida en la capital era desmedida. En aquellos años Madrid se encontraba inmersa en un importante proceso de transformación que la convertiría décadas más tarde en una gran metrópoli. No obstante, en estos años de definición de su propia trama urbana la ciudad estaba colapsada por los tranvías y el creciente tráfico de automóviles. La Compañía Metropolitano Alfonso XIII, fundada por los ingenieros Miguel Otamendi, Antonio G. Echarte y Carlos Mendoza, consiguió materializar en un eficaz proyecto la idea de un nuevo tipo de transporte que discurría por debajo del nivel de calle. Este tipo de ferrocarril subterráneo planteó la aparición de unos nuevos parámetros espaciales que modificaron la percepción que los viajeros urbanos tenían de la metrópoli. Las bocas de metro se convirtieron enseguida en hitos en torno a los cuales se podían tomar referencias y orientarse en la trama urbana. La descontextualización del viaje respecto al entorno físico en el cual se produce ese desplazamiento direccional convirtió la experiencia de viajar a través del subsuelo en algo futurista para la época. Y con ello cambió la concepción de la ciudad, dejamos de percibirla en su totalidad para experimentarla de manera fragmentada por esos lapsos de tiempo que transcurren entre la entrada y la salida del metro. A través de los dibujos que Antonio Palacios Ramilo (Porriño 1874 ? Madrid 1945), arquitecto oficial de la Compañía, realizó para el diseño de las estaciones, vestíbulos y bocas de acceso podemos sentir la búsqueda constante de calidez y luminosidad como contraste frente a la imagen estereotipada fría y oscura de una caverna excavada bajo tierra. La introducción de la luz cenital en los vestíbulos, el recubrimiento de todas las superficies de tránsito con azulejos blancos que reflejan y multiplican la luz y el exquisito diseño de todos los detalles demuestran el interés del arquitecto por dignificar en todo momento estos nuevos espacios subterráneos, caracterizando con una identidad propia esta nueva tipología arquitectónica, y convirtiendo el viaje en metro en una experiencia sensorial innovadora. Abstract: n the early twentieth century Madrid was undergoing a major transformation that would make decades later in a large metropolis. However, in these years of defining its own urban grid the city was jammed with trams and the increasing car traffic. In 1919, the Com- pany Metropolitan Alfonso XIII, got into an effective project materialize the idea of a new type of transport that ran below the calle. Analizaremos experience as a paradigm shift in the trip meter without spatial reference. We will study the elements of this under- ground network and the relationships between them are generated: nodes , flows, transit spaces, waiting areas and up... And finally , will point to what extent the construction of this transport has influenced and modified the urban scene on the slope where the meter has become an element of our everyday life.

Antonio Palacios y el ferrocarril metropolitano. Patrimonio Industrial en el Metro de Madrid

Antonio Palacios Ramilo, relevante arquitecto de la 1ª mitad del siglo XX, responsable de emblemáticos edificios del centro de la capital (Círculo de Bellas Artes, Palacio de Correos...), es también autor de otro tipo de arquitectura mucho menos conocida. En su calidad de arquitecto oficial de la Compañía Metropolitana Alfonso XIII, diseñó no sólo las estaciones, bocas y templetes del metro de Madrid, sino también toda una serie de edificios auxiliares entre los que destacan las centrales y subestaciones eléctricas. Analizaremos, por tanto, el modo de intervención de Palacios en la arquitectura industrial respecto al resto de su obra y estudiaremos el estado en que se encuentra actualmente este patrimonio, distinguiendo entre los casos en los que ha habido una intervención restauradora (Nave de Motores en Pacífico, Estación de Chamberí), los que están en desuso (subestaciones de Quevedo y Salamanca...) y los elementos que ya han desaparecido (templetes de Sol y Gran Vía).

Proyecto de construcción de la línea de Metro Ligero: tramo Monterrozas-Las Rozas

El presente Proyecto Constructivo define las obras necesarias para la construcción de la infraestructura de la línea de Metro Ligero Monterrozas- Las Rozas. La línea comienza discurriendo por el bulevar central de la Calle Camilo José Cela, donde efectúa dos paradas. La primera se encuentra a la altura de la Biblioteca Leon Tolstoi, mientras que la segunda se sitúa entre el Heron City y Las Rozas Village. Se diseña así la línea de transporte guiado urbano tipo metro ligero, y la definición alcanza todas las obras precisas para su ejecución: demoliciones, movimiento de tierras, urbanización y viales, estructuras, obras subterráneas, subestaciones (obra civil), drenaje, integración ambiental, paradas y estaciones, plataforma y superestructura, desvíos de tráfico, reposición de servicios afectados y obras complementarias

Interleaved concatenated codes: New perspectives on approaching the Shannon limit

The last few years have witnessed a significant decrease in the gap between the Shannon channel capacity limit and what is practically achievable. Progress has resulted from novel extensions of previously known coding techniques involving interleaved concatenated codes. A considerable body of simulation results is now available, supported by an important but limited theoretical basis. This paper presents a computational technique which further ties simulation results to the known theory and reveals a considerable reduction in the complexity required to approach the Shannon limit.

Synthetic genes for glycoprotein design and the elucidation of hydroxyproline-O-glycosylation codes

Design of hydroxyproline (Hyp)-rich glycoproteins (HRGPs) offers an approach for the structural and functional analysis of these wall components, which are broadly implicated in plant growth and development. HRGPs consist of multiple small repetitive “glycomodules” extensively O-glycosylated through the Hyp residues. The patterns of Hyp-O-glycosylation are putatively coded by the primary sequence as described by the Hyp contiguity hypothesis, which predicts contiguous Hyp residues to be attachment sites of small arabinooligosaccharides (1–5 Ara residues/Hyp); while clustered, noncontiguous Hyp residues are sites of arabinogalactan polysaccharide attachment. As a test, we designed two simple HRGPs as fusion proteins with green fluorescent protein. The first was a repetitive Ser-Hyp motif that encoded only clustered noncontiguous Hyp residues, predicted polysaccharide addition sites. The resulting glycoprotein had arabinogalactan polysaccharide O-linked to all Hyp residues. The second construct, based on the consensus sequence of a gum arabic HRGP, contained both arabinogalactan and arabinooligosaccharide addition sites and, as predicted, gave a product that contained both saccharide types. These results identify an O-glycosylation code of plants.

The affected gene underlying the class K glycosylphosphatidylinositol (GPI) surface protein defect codes for the GPI transamidase

The final step in glycosylphosphatidylinositol (GPI) anchoring of cell surface proteins consists of a transamidation reaction in which preassembled GPI donors are substituted for C-terminal signal sequences in nascent polypeptides. In previous studies we described a human K562 cell mutant, termed class K, that accumulates fully assembled GPI units but is unable to transfer them to N-terminally processed proproteins. In further work we showed that, unlike wild-type microsomes, microsomes from these cells are unable to support C-terminal interaction of proproteins with the small nucleophiles hydrazine or hydroxylamine, and that the cells thus are defective in transamidation. In this study, using a modified recombinant vaccinia transient transfection system in conjunction with a composite cDNA prepared by 5′ extension of an existing GenBank sequence, we found that the genetic element affected in these cells corresponds to the human homolog of yGPI8, a gene affected in a yeast mutant strain exhibiting similar accumulation of GPI donors without transfer. hGPI8 gives rise to mRNAs of 1.6 and 1.9 kb, both encoding a protein of 395 amino acids that varies in cells with their ability to couple GPIs to proteins. The gene spans ≈25 kb of DNA on chromosome 1. Reconstitution of class K cells with hGPI8 abolishes their accumulation of GPI precursors and restores C-terminal processing of GPI-anchored proteins. Also, hGPI8 restores the ability of microsomes from the mutant cells to yield an active carbonyl in the presence of a proprotein which is considered to be an intermediate in catalysis by a transamidase.

A single gene of chloroplast origin codes for mitochondrial and chloroplastic methionyl–tRNA synthetase in Arabidopsis thaliana

One-fifth of the tRNAs used in plant mitochondrial translation is coded for by chloroplast-derived tRNA genes. To understand how aminoacyl–tRNA synthetases have adapted to the presence of these tRNAs in mitochondria, we have cloned an Arabidopsis thaliana cDNA coding for a methionyl–tRNA synthetase. This enzyme was chosen because chloroplast-like elongator tRNAMet genes have been described in several plant species, including A. thaliana. We demonstrate here that the isolated cDNA codes for both the chloroplastic and the mitochondrial methionyl–tRNA synthetase (MetRS). The protein is transported into isolated chloroplasts and mitochondria and is processed to its mature form in both organelles. Transient expression assays using the green fluorescent protein demonstrated that the N-terminal region of the MetRS is sufficient to address the protein to both chloroplasts and mitochondria. Moreover, characterization of MetRS activities from mitochondria and chloroplasts of pea showed that only one MetRS activity exists in each organelle and that both are indistinguishable by their behavior on ion exchange and hydrophobic chromatographies. The high degree of sequence similarity between A. thaliana and Synechocystis MetRS strongly suggests that the A. thaliana MetRS gene described here is of chloroplast origin.

Class I release factors in ciliates with variant genetic codes

In eukaryotes with the universal genetic code a single class I release factor (eRF1) most probably recognizes all stop codons (UAA, UAG and UGA) and is essential for termination of nascent peptide synthesis. It is well established that stop codons have been reassigned to amino acid codons at least three times among ciliates. The codon specificities of ciliate eRF1s must have been modified to accommodate the variant codes. In this study we have amplified, cloned and sequenced eRF1 genes of two hypotrichous ciliates, Oxytricha trifallax (UAA and UAG for Gln) and Euplotes aediculatus (UGA for Cys). We also sequenced/identified three protist and two archaeal class I RF genes to enlarge the database of eRF1/aRF1s with the universal code. Extensive comparisons between universal code eRF1s and those of Oxytricha, Euplotes and Tetrahymena, which represent three lineages that acquired variant codes independently, provide important clues to identify stop codon-binding regions in eRF1. Domain 1 in the five ciliate eRF1s, particulary the TASNIKS heptapeptide and its adjacent region, differs significantly from domain 1 in universal code eRF1s. This observation suggests that domain 1 contains the codon recognition site, but that the mechanism of eRF1 codon recognition may be more complex than proposed by Nakamura et al. or Knight and Landweber.

Ensemble codes involving hippocampal neurons are at risk during delayed performance tests

Multielectrode recording techniques were used to record ensemble activity from 10 to 16 simultaneously active CA1 and CA3 neurons in the rat hippocampus during performance of a spatial delayed-nonmatch-to-sample task. Extracted sources of variance were used to assess the nature of two different types of errors that accounted for 30% of total trials. The two types of errors included ensemble “miscodes” of sample phase information and errors associated with delay-dependent corruption or disappearance of sample information at the time of the nonmatch response. Statistical assessment of trial sequences and associated “strength” of hippocampal ensemble codes revealed that miscoded error trials always followed delay-dependent error trials in which encoding was “weak,” indicating that the two types of errors were “linked.” It was determined that the occurrence of weakly encoded, delay-dependent error trials initiated an ensemble encoding “strategy” that increased the chances of being correct on the next trial and avoided the occurrence of further delay-dependent errors. Unexpectedly, the strategy involved “strongly” encoding response position information from the prior (delay-dependent) error trial and carrying it forward to the sample phase of the next trial. This produced a miscode type error on trials in which the “carried over” information obliterated encoding of the sample phase response on the next trial. Application of this strategy, irrespective of outcome, was sufficient to reorient the animal to the proper between trial sequence of response contingencies (nonmatch-to-sample) and boost performance to 73% correct on subsequent trials. The capacity for ensemble analyses of strength of information encoding combined with statistical assessment of trial sequences therefore provided unique insight into the “dynamic” nature of the role hippocampus plays in delay type memory tasks.

Neural codes: Firing rates and beyond

Computational neuroscience has contributed significantly to our understanding of higher brain function by combining experimental neurobiology, psychophysics, modeling, and mathematical analysis. This article reviews recent advances in a key area: neural coding and information processing. It is shown that synapses are capable of supporting computations based on highly structured temporal codes. Such codes could provide a substrate for unambiguous representations of complex stimuli and be used to solve difficult cognitive tasks, such as the binding problem. Unsupervised learning rules could generate the circuitry required for precise temporal codes. Together, these results indicate that neural systems perform a rich repertoire of computations based on action potential timing.

A unique human gene that spans over 230 kb in the human chromosome 8p11-12 and codes multiple family proteins sharing RNA-binding motifs.

A unique gene, RBP-MS, spanning over 230 kb in the human chromosome 8p11-12 near the Werner syndrome gene locus is described. The single-copy RBP-MS gene is alternatively spliced, resulting in a family of at least 12 transcripts (average length of 1.5 kb). Nine different types of cDNAs that encode an RNa-binding motif at the N terminus and helix-rich sequences at the C terminus have been identified thus far. Among the 16 exons identified, four 5'-proximal exons contained sequences homologous to the RNA-binding domain of Drosophila couch potato gene. Northern blot analysis showed that the RBP-MS gene was expressed strongly in the heart, prostate, intestine, and ovary, and poorly in the skeletal muscle, spleen, thymus, brain, and peripheral leukocytes. The possible role of this gene in RNA metabolism is discussed.

Cloning and expression in Escherichia coli of the OGG1 gene of Saccharomyces cerevisiae, which codes for a DNA glycosylase that excises 7,8-dihydro-8-oxoguanine and 2,6-diamino-4-hydroxy-5-N-methylformamidopyrimidine.

A spontaneous mutator strain of Escherichia coli (fpg mutY) was used to clone the OGG1 gene of Saccharomyces cerevisiae, which encodes a DNA glycosylase activity that excises 7,8-dihydro-8-oxoguanine (8-OxoG). E. coli (fpg mutY) was transformed by a yeast DNA library, and clones that showed a reduced spontaneous mutagenesis were selected. The antimutator activity was associated with pYSB10, an 11-kbp recombinant plasmid. Cell-free extracts of E. coli (fpg mutY) harboring pYSB10 possess an enzymatic activity that cleaves a 34-mer oligonucleotide containing a single 8-oxoG opposite a cytosine (8-OxoG/C). The yeast DNA fragment of 1.7 kbp that suppresses spontaneous mutagenesis and overproduces the 8-OxoG/C cleavage activity was sequenced and mapped to chromosome XIII. DNA sequencing identified an open reading frame, designated OGG1, which encodes a protein of 376 amino acids with a molecular mass of 43 kDa. The OGG1 gene was inserted in plasmid pUC19, yielding pYSB110. E. coli (fpg) harboring pYSB110 was used to purify the Ogg1 protein of S. cerevisiae to apparent homogeneity. The Ogg1 protein possesses a DNA glycosylase activity that releases 8-OxoG and 2,6-diamino-4-hydroxy-5-N-methylformamidopyrimidine. The Ogg1 protein preferentially incises DNA that contains 8-OxoG opposite cytosine (8-OxoG/C) or thymine (8-OxoG/T). In contrast, Ogg1 protein does not incise the duplex where an adenine is placed opposite 8-OxoG (8-OxoG/A). The mechanism of strand cleavage by Ogg1 protein is probably due to the excision of 8-OxoG followed by a beta-elimination at the resulting apurinic/apyrimidinic site.

A close relative of the adrenoleukodystrophy (ALD) gene codes for a peroxisomal protein with a specific expression pattern.

Adrenoleukodystrophy (ALD), a severe demyelinating disease, is caused by mutations in a gene coding for a peroxisomal membrane protein (ALDP), which belongs to the superfamily of ATP binding cassette (ABC) transporters and has the structure of a half transporter. ALDP showed 38% sequence identity with another peroxisomal membrane protein, PMP70, up to now its closest homologue. We describe here the cloning and characterization of a mouse ALD-related gene (ALDR), which codes for a protein with 66% identity with ALDP and shares the same half transporter structure. The ALDR protein was overexpressed in COS cells and was found to be associated with the peroxisomes. The ALD and ALDR genes show overlapping but clearly distinct expression patterns in mouse and may thus play similar but nonequivalent roles. The ALDR gene, which appears highly conserved in man, is a candidate for being a modifier gene that could account for some of the extreme phenotypic variability of ALD. The ALDR gene is also a candidate for being implicated in one of the complementation groups of Zellweger syndrome, a genetically heterogeneous disorder of peroxisome biogenesis, rare cases of which were found to be associated with mutations in the PMP70 (PXMP1) gene.