Vol.26, No.3, 2002-Table of Contents
  • Water relations and leaf growth rate of three Agropyron genotypes under water stress
  • Abstract The effects of water stress on leaf water relations and growth are reported for three perennial tussock grass genotypes under glasshouse conditions. Studies were performed in genotypes El Palmar INTA and Selección Anguil of Agropyron scabrifolium (Döell) Parodi, and El Vizcachero of A. elongatum (Host) Beauv. Agropyron scabrifolium El Palmar INTA is native to a region with warm-temperate and humid climate without a dry season, and an average annual precipitation of 900 mm. Agropyron scabrifolium Selección Anguil comes from a region with a sub-humid, dry to semiarid climate and a mean annual precipitation of 600 mm. Agropyron elongatum is a… More
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  • In vitro propagation of Opuntia ellisiana Griff. and acclimatization to field conditions
  • Abstract The genus Opuntia is a valuable forage resource in arid and semiarid lands during periods of drought and shortage of herbaceous plants. However, absolute minimum temperatures in the plains of Mendoza represent a limiting factor to cultivate several species.
    Opuntia ellisiana is a cold hardy species, so the goals of this study were to massively propagate it using in vitro culture techniques, and then to acclimatize plantlets obtained to field conditions.
    Different sterilization protocols were tested. Areoles were isolated in laminar airflow cabinet, and cultured on Murashige-Skoog medium, supplemented with sucrose and different BAP and IBA combinations. Explants were… More
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  • Effects of high molybdenum intake on 1,2-dimethylhydrazine-induced intestinal tumors in rats
  • Abstract Wistar male rats, 3 months of age were given ad-libitum a nutritionally adequate diet and demineralized drinking water. The Molybdenum (Mo) and Tungsten (W) were provided in the drinking water at 200 ppm concentration. Intestinal tumors were induced by 1,2-dimethylhydrazine (DMH) given subcutaneously as 16 weekly doses at 20 mg/kg body weight. Mo in the form of (NH4)6 Mo7O24 4H2O or W in the form of (Na2 WO4) were provided in the drinking water two months before the first DMH treatment and were continued during 4 months more until the last DMH treatment. Three months after the last carcinogen injection,… More
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  • Ultrastructural characteristics of the lung of Melanophryniscus stelzneri stelzneri (Weyenberg, 1875) (Anura, Bufonidae)
  • Abstract The lung of the toad, Melanophryniscus stelzneri stelzneri was studied using scanning and transmission electron microscopy. In M.s.stelzneri the parenchyma forms a polygonal network arrangement, therefore the parenchyma is edicular. These spaces are delimited by the interconnection of third order septa which are covered by respiratory epithelium. Small patches of ciliated epithelium without goblet cells appear irregularly distributed on the septa. The respiratory epithelium consists of one type of pneumocyte, which shows characteristics of both type I and type II alveolar cells of higher vertebrates. The pneumocytes are irregular in shape and possess attenuated cytoplasmic processes, which spread around the… More
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