Análisis comparativo de normativas arquitectónicas en estaciones de bomberos de Chile, Colombia, Venezuela y Perú

El método de análisis comparativo ad hoc, aplicado a los estándares de las estaciones de bomberos en ámbitos urbanos de países andinos sudamericanos, permitió evaluar similitudes y diferencias entre las normas o regulaciones implícitas de Venezuela, Colombia, Chile y Perú, con la finalidad de obtener criterios o lineamientos de diseño para nuevas estaciones en Lima. Entre los resultados obtenidos se han establecidos criterios de localización basados en aspectos como: área de cobertura, emplazamiento y riesgos para la edificación, servicios públicos, red de comunicación de emergencias, entre otros. El programa arquitectónico consta de zonas para: equipos y mantenimiento, entrenamiento y capacitación, residencial y de esparcimiento, administrativo y de servicios. Los criterios de diseño arquitectónico se agruparon en: aspectos formales, funcionales, y de especialidades técnicas que condicionan la arquitectura. Adicionalmente, se concluyó que en la zona urbana limeña para el programa arquitectónico se requiere como mínimo 1,317.6 m2 de área techada

Phytochelatin Synthesis Is Essential for the Detoxification of Excess Zinc and Contributes Significantly to the Accumulation of Zinc1[W][OA]

The synthesis of phytochelatins (PCs) is essential for the detoxification of nonessential metals and metalloids such as cadmium and arsenic in plants and a variety of other organisms. To our knowledge, no direct evidence for a role of PCs in essential metal homeostasis has been reported to date. Prompted by observations in Schizosaccharomyces pombe and Saccharomyces cerevisiae indicating a contribution of PC synthase expression to Zn2+ sequestration, we investigated a known PC-deficient Arabidopsis (Arabidopsis thaliana) mutant, cad1-3, and a newly isolated second strong allele, cad1-6, with respect to zinc (Zn) homeostasis. We found that in a medium with low cation content PC-deficient mutants show pronounced Zn2+ hypersensitivity. This phenotype is of comparable strength to the well-documented Cd2+ hypersensitivity of cad1 mutants. PC deficiency also results in significant reduction in root Zn accumulation. To be able to sensitively measure PC accumulation, we established an assay using capillary liquid chromatography coupled to electrospray ionization quadrupole time-of-flight mass spectrometry of derivatized extracts. Plants grown under control conditions consistently showed PC2 accumulation. Analysis of plants treated with same-effect concentrations revealed that Zn2+-elicited PC2 accumulation in roots reached about 30% of the level of Cd2+-elicited PC2 accumulation. We conclude from these data that PC formation is essential for Zn2+ tolerance and provides driving force for the accumulation of Zn. This function might also help explain the mysterious occurrence of PC synthase genes throughout the plant kingdom and in a wide range of other organisms

Zinc hyperaccumulation: a model to examine metal homeostasis in plants

The plant Arabidopsis halleri exhibits naturally selected metal hypertolerance and extraordinarily high levels of leaf metal accumulation. Metal hyperaccumulator species attract interest as they represent an extreme end of natural variation of the metal homeostasis network. This might be useful to reveal the global functioning of metal homeostasis networks and uncover key nodes whose alterations can drastically modify metal accumulation and tolerance. In addition, metal hyperaccumulation is a compelling model to study adaptation. In the last few years, major progress has been achieved in our understanding of the mechanisms underlying metal hyperaccumulation in A. halleri. High rates of metal uptake by roots, root-to-shoot translocation and efficient shoot vacuolar sequestration play central roles in determining hyperaccumulation and hypertolerance. Enhanced functions of several metal transporter-encoding genes result from gene copy number amplification and/or (cis)-regulatory changes. We will describe the function of several transporters in zinc and cadmium hyperaccumulation and hypertolerance, and in the adjustment of nutrient homeostasis in A. halleri. Recent work aiming to determine if selection acted during the evolutionary history of A. halleri on a loci required for metal tolerance and accumulation will be presented

Nucleotide sequence diversity across the <i>HMA4</i> genomic region in <i>A. halleri</i>.

<p>(A) Average pairwise nucleotide sequence diversity π across the <i>HMA4</i> genomic region in <i>A. halleri</i> ssp. <i>halleri</i>. (B) Molecular population genetic statistical tests for the deviation from neutrality, Tajima's <i>D</i>, Fu and Li's <i>D</i>*, and Fu and Li's <i>F</i>* in <i>A. halleri</i> ssp. <i>halleri</i>. Differently colored symbols are defined by concordantly colored axis titles. Vertical arrows indicate positions of sequenced segments. The region of <i>HMA4</i> triplication is shaded in grey. Marked in red color are stretches of sequence that are present in several, almost identical copies (horizontal bars; detected using NCBI MEGABLAST program with default settings and a word size of 256; see <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003707#pgen.1003707.s010" target="_blank">Table S3</a>), and sequenced segments therein (arrows, fonts, red open symbols instead of closed black symbols in panel (A)). Direction of transcription (triangular arrow) is given for each gene (rectangle, Arabidopsis Genome Identifier code of <i>A. thaliana</i> ortholog), with genes of unknown position in <i>A. halleri</i> shown in grey. For additional information see <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003707#pgen.1003707.s009" target="_blank">Table S2</a>.</p