Occurrence of continuous Holocene pinewoods (Pinus sylvestris L.) in the Eastern Central System (Spain) inferred from macroremains. New data from the Sandria site

The present study of plant macroremains, wood fragments and pine cones from the eastern Central System (Ayllón Massif) for the upper Holocene establishes the presence in the area of Pinus sylvestris, Juniperus sp. and Betula sp. The occurrence of the Scots pine between ca. 4000 and 2000 yr BP allows us to confirm the natural origin of the species in the area at an altitude of 1350 m asl, a fact that clashes with numerous former phytosociological interpretations and which highlights the relevance of the current pine forests, as well as the need to include them within some status of legal protection. Furthermore, for the first time on the Iberian Peninsula, and considering the nearby Valdojos site, we employ only macroremains to demonstrate the presence of a pine forest practically throughout the Holocene, thus evidencing maximum conditions of stability and resilience for this type of plant community. As occurs with other vegetal formations identified by means of pollen analysis, this forest could have undergone radical alterations only in recent historical times as a result of anthropic action, as appears to be indicated by the evolution of the sedimentary basin of the Sandria valley.Departamento de Sistemas y Recursos Naturales, Universidad Politécnica de Madrid, EspañaInstituto Geológico y Minero de España, Españ

Condicionantes geomorfológicos y sedimentológicos para la conservación excepcional del bosque subfósil holoceno del valle de Sandria (Campisábalos, Guadalajara)

En este trabajo se muestran los resultados del estudio geomorfológico, sedimentológico y geofísico del relleno sedimentario holoceno del valle del arroyo de Sandria (Campisábalos, Guadalajara), como parte integrante del estudio de los yacimientos paleontológicos existentes en la zona. A partir del extraordinario material subfósil leñoso encontrado en los yacimientos se han obtenido nuevos datos paleoecológicos que van a permitir obtener las pautas de cambio de la vegetación. El relleno sedimentario del yacimiento del arroyo de Sandria muestra una potencia que oscila entre los 2 y 6 m. Está formado por arenas finas, limos, margas orgánicas y turbas que se han interpretado como un ambiente de sedimentación de tipo lacustre y palustre. El cierre del valle fluvial de Sandria podría deberse a varias circunstancias, unidas o aisladas: la oclusión del valle a su salida por la progradación de un cono de deyección, la posible existencia de un pequeño alto estructural y/o la disolución diferencial del sustrato carbonatado que ha originado localmente pequeñas cubetas que coinciden con los depocentrosInstituto Geológico y Minero de España, EspañaEscuela de Ingeniería de Montes, Forestal y del Medio Natural, Universidad Politécnica de Madrid, EspañaDepartamento de Ingeniería del Terreno, Escuela Politécnica Superior de Ávila, Universidad de Salamanca, EspañaGeoland Services SL., Españ

Cholestasis Induced by Total Parenteral Nutrition

Parenteral nutrition is a life-saving treatment for patients who have acute and chronic intestinal failure. Severe cholestasis induced by total parental nutrition (TPN-IC) is characterized by bile duct regeneration, portal inflammation, and fibrosis. Its progression could be very rapid, and in some patients liver cirrhosis may develop in few months. This article describes the definition, incidence, hepatic changes, histopathologic findings, risk factors, pathogenesis, and clinical implications of TPN-IC. The goal is to improve hospital and home management, quality of life, and prognosis of patients requiring parenteral nutrition. © 2008 Elsevier Inc. All rights reserved

Grx5 Is a Mitochondrial Glutaredoxin Required for the Activity of Iron/Sulfur Enzymes

Yeast cells contain a family of three monothiol glutaredoxins: Grx3, 4, and 5. Absence of Grx5 leads to constitutive oxidative damage, exacerbating that caused by external oxidants. Phenotypic defects associated with the absence of Grx5 are suppressed by overexpression of SSQ1 and ISA2, two genes involved in the synthesis and assembly of iron/sulfur clusters into proteins. Grx5 localizes at the mitochondrial matrix, like other proteins involved in the synthesis of these clusters, and the mature form lacks the first 29 amino acids of the translation product. Absence of Grx5 causes: 1) iron accumulation in the cell, which in turn could promote oxidative damage, and 2) inactivation of enzymes requiring iron/sulfur clusters for their activity. Reduction of iron levels in grx5 null mutants does not restore the activity of iron/sulfur enzymes, and cell growth defects are not suppressed in anaerobiosis or in the presence of disulfide reductants. Hence, Grx5 forms part of the mitochondrial machinery involved in the synthesis and assembly of iron/sulfur centers