Browsing by Author "Moreno, R"

Now showing 1 - 4 of 4
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    A putative, ubiquitin-dependent mechanism for the recognition and elimination of defective spermatozoa in the mammalian epididymis
    (2001) Sutovsky, P; Moreno, R; Ramalho-Santos, J; Dominko, T; Winston, WE; Schatten, G
    The normal structure and function of sperm are prerequisites for successful fertilization and embryonic development, but little is known about how defective sperm are eliminated during mammalian spermatogenesis. Here, we describe a ubiquitin-dependent, sperm quality control mechanism that resides in the mammalian epididymis, the site of sperm maturation and storage. We used immunofluorescence, electron microscopy, western blotting and pulse-chase experiments to show that ubiquitin is secreted by the epididymal epithelium and binds to the surface of defective sperm. Most of the ubiquitinated sperm are subsequently phagocytosed by the epididymal epithelial cells. A portion of defective sperm escapes phagocytosis and can be found in the ejaculate. Cultured epididymal cells maintain their ability to produce ubiquitin and phagocytose the defective sperm, as well as the ubiquitin-coated microspheres, in vitro. The surprising phenomenon of cell-surface ubiquitination in defective sperm provides a possible mechanism for sperm quality control in mammals and a new marker of semen abnormalities in men and animals.
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    Bleomycin-induced chronic lung damage does not resemble human idiopathic pulmonary fibrosis
    (AMER THORACIC SOC, 2001) Borzone, G; Moreno, R; Urrea, R; Meneses, M; Oyarzun, M; Lisboa, C
    Administration of bleomycin into the lungs of experimental animals has been utilized as a model to understand human pulmonary fibrosis. Most of the studies, however, have focused on early stages of the lung reaction. We hypothesized that chronic stages of the model may not mimic idiopathic pulmonary fibrosis, since in preliminary studies, lung volume and compliance were not decreased. Eight male Sprague-Dawley rats receiving intratracheal bleomycin (0.5 U/100 g body weight) underwent measurement of FRC, inspiratory capacity, and lung compliance 120 d later. Lung histologic changes were evaluated using light microscopy. Eight rats without intervention served as controls. Results show that our model, in early stages, has histologic changes no different from those previously described elsewhere. In chronic stages, however, the model does not behave as a restrictive syndrome: FRC is normal or increased, whereas lung compliance is normal. Focal peribronchiolar inflammation and fibrosis associated with paracicatricial emphysematous changes are the main histologic features of long-term lung remodeling after bleomycin. We conclude that while the chronic stages of the model may be informative in understanding mechanisms of fibrosis, care should be taken not to extrapolate to human idiopathic pulmonary fibrosis. We speculate that the model might resemble a particular subgroup of human interstitial lung disease, namely, those involving peribronchiolar structures.
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    Purification and biochemical characterization of a trypsin-like enzyme present in the sperm of the rock shrimp, Rhynchocinetes typus
    (2001) Bustamante, E; Palomino, J; Amoroso, A; Moreno, R; Barros, C
    The aim of the present work was to isolate, purify and characterize a trypsin-like enzyme from the sperm of the rock shrimp, Rhynchocinetes typus. Sperm proteins were extracted with 1 mM HCl in 10% glycerol at pH 3.0. Purification of the trypsin-like substance was effected by affinity chromatography using SBTI-agarose, yielding a specific activity on BAEE as substrate of 787 U/mg, with a recovery rate of 34%. Enzymatic activity was maximal at 27 degreesC, pH of 8.0, 50 mM Ca2+ and 30 mM Mg2+. One hundred percent inhibition of enzymatic activity was obtained at 0.05 mM Zn2+. Kinetic analysis showed that the K-M on BAEE as substrate at pH 8.0 was 2.5 x 10(-5) M and the V-MAX reached was 198 U. It was also found that the enzyme had a substrate inhibition at concentrations higher than 0.06 mM of BAEE. These findings suggest that thin enzyme has similar characteristics to other trypsin-like enzymes including acrosin.
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    Two-dimensional cellular automaton model for mixed-culture biofilm
    (2004) Pizarro Puccio, Gonzalo Ernesto; Garcia, C; Moreno, R; Sepulveda, ME