Antecedentes, organización y programas del Centro Latinoamericano de Documentación Económica y Social = Background, organization and programmes of the Latin American Centre for Economic and Social Documentation

Incluye Bibliografía

Evolutionary dynamics of retrotransposable elements Rex1, Rex3 and Rex6 in neotropical cichlid genomes

Background: Transposable elements (TEs) have the potential to produce broad changes in the genomes of their hosts, acting as a type of evolutionary toolbox and generating a collection of new regulatory and coding sequences. Several TE classes have been studied in Neotropical cichlids; however, the information gained from these studies is restricted to the physical chromosome mapping, whereas the genetic diversity of the TEs remains unknown. Therefore, the genomic organization of the non-LTR retrotransposons Rex1, Rex3, and Rex6 in five Amazonian cichlid species was evaluated using physical chromosome mapping and DNA sequencing to provide information about the role of TEs in the evolution of cichlid genomes. Results: Physical mapping revealed abundant TE clusters dispersed throughout the chromosomes. Furthermore, several species showed conspicuous clusters accumulation in the centromeric and terminal portions of the chromosomes. These TE chromosomal sites are associated with both heterochromatic and euchromatic regions. A higher number of Rex1 clusters were observed among the derived species. The Rex1 and Rex3 nucleotide sequences were more conserved in the basal species than in the derived species; however, this pattern was not observed in Rex6. In addition, it was possible to observe conserved blocks corresponding to the reverse transcriptase fragment of the Rex1 and Rex3 clones and to the endonuclease of Rex6. Conclusion: Our data showed no congruence between the Bayesian trees generated for Rex1, Rex3 and Rex6 of cichlid species and phylogenetic hypothesis described for the group. Rex1 and Rex3 nucleotide sequences were more conserved in the basal species whereas Rex6 exhibited high substitution rates in both basal and derived species. The distribution of Rex elements in cichlid genomes suggests that such elements are under the action of evolutionary mechanisms that lead to their accumulation in particular chromosome regions, mostly in heterochromatins. © 2013 Schneider et al.; licensee BioMed Central Ltd.

XAS/WAXS time-resolved phase speciation of chlorine LDH thermal transformation: Emerging roles of isovalent metal substitution

The XAS/WAXS time-resolved method was applied for unraveling the complex mechanisms arising from the evolution of several metastable intermediates during the degradation of chlorine layered double hydroxide (LDH) upon heating to 450 °C, i.e., Zn2Al(OH)6·nH2O, ZnCuAl(OH)6·nH2O, Zn2Al 0.75Fe0.25(OH)6·nH2O, and ZnCuAl0.5Fe0.5(OH)6·nH2O. After a contraction of the interlamellar distance, attributed to the loss of intracrystalline water molecules, this distance experiences an expansion (T > 175-225 °C) before the breakdown of the lamellar framework around 275-295 °C. Amorphous prenucleus clusters with crystallo-chemical local order of zinc-based oxide and zinc-based spinel phases, and if any of copper-based oxide, are formed at T > 175-225 °C well before the loss of stacking of LDH layers. This distance expansion has been ascribed to the migration of Zn II from octahedral layers to tetrahedral sites in the interlayer space, nucleating the nano-ZnO or nano-ZnM2O4 (M = Al or Fe) amorphous prenuclei. The transformation of these nano-ZnO clusters toward ZnO crystallites proceeds through an agglomeration process occurring before the complete loss of layer stacking for Zn2Al(OH)6· nH2O and Zn2Al0.75Fe0.25(OH) 6·nH2O. For ZnCuAl(OH)6·nH 2O and ZnCuAl0.5Fe0.5(OH)6· nH2O, a cooperative effect between the formation of nano-CuO and nano-ZnAl2O4 amorphous clusters facilitates the topochemical transformation of LDH to spinel due to the contribution of octahedral CuII vacancy to ZnII diffusion. © 2013 American Chemical Society.

Ninth Regional Conference on Women in Latin America and the Caribbean. Mexico City, 10-12 June 2004: background information

Includes bibliography

Séptima Conferencia Regional sobre la Integración de la Mujer en el Desarrollo Económico y Social de América Latina y el Caribe: folleto informativo = Seventh Session of the Regional Conference on the Integration of Women into the Economic and Social Development of Latin America and the Caribbean: background information

Incluye Bibliografía

Antecedentes y objetivos de la Conferencia, temario provisional, anotaciones al temario provisional = Background and objectives of the Conference, provisional agenda, annotations of the provisional agenda = Historique et objectifs de la Conférence, ordre du jour provisoire, annotations à l'ordre du jour provisoire

Incluye Bibliografía

Background and mandate of Ad Hoc Working Group for Transportation Planning

Contiene los antecedentes del Grupo Especial de Trabajo sobre Planificacion del Transporte y el mandato, acordado por los Ministros en la Quinta Sesion del CDCC, sobre el desarrollo de un programa en el sector transporte, en especial transporte maritimo, en base a recomendaciones hechas en estudios anteriores.

Background and mandate of Ad Hoc Working Group of Planners in Agriculture

Contiene una vision general del proposito de este grupo de trabajo del CDCC en lo que se refiere a las tareas de formular estrategias para el desarrollo del sector agricola en la region.

Antecedentes para la participación de los países latinoamericanos en el Vigesimocuarto Período de Sesiones de la Comisión de Estadística de Naciones Unidas = Background information for the participation of Latin American countries in the Twenty-fourth Session of the United Nations Statistical Commission

Describe la agenda de la proxima reunion, comenta temas de esa agenda en los que hay programas previstos o en ejecucion, y enumera elementos del programa de trabajo de la Oficina de Estadistica de las NU sobre los cuales la Comision debe tomar decisiones.