Examinando por Autor "Pinto, Rodrigo"

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    Ítem
    Expression of a novel non-coding mitochondrial RNA in human proliferating cells
    (Oxford University Press, 2007-12-01) Villegas, Jaime; Burzio, Veronica; Villota, Claudio; Landerer, Eduardo; Martinez, Ronny; Santander, Marcela; Martinez, Rodrigo; Pinto, Rodrigo; Vera, Maria I.; Boccardo, Enrique; Villa, Luisa L.; Burzio, Luis O.
    Previously, we reported the presence in mouse cells of a mitochondrial RNA which contains an inverted repeat (IR) of 121 nucleotides (nt) covalently linked to the 5 end of the mitochondrial 16S RNA (16S mtrRNA). Here, we report the structure of an equivalent transcript of 2374 nt which is over-expressed in human proliferating cells but not in resting cells. The transcript contains a hairpin structure comprising an IR of 815 nt linked to the 5 end of the 16S mtrRNA and forming a long double-stranded structure or stem and a loop of 40 nt. The stem is resistant to RNase A and can be detected and isolated after digestion with the enzyme. This novel transcript is a non-coding RNA (ncRNA) and several evidences suggest that the transcript is synthesized in mitochondria. The expression of this transcript can be induced in resting lymphocytes stimulated with phytohaemagglutinin (PHA). Moreover, aphidicolin treatment of DU145 cells reversibly blocks proliferation and expression of the transcript. If the drug is removed, the cells re-assume proliferation and over-express the ncmtRNA. These results suggest that the expression of the ncmtRNA correlates with the replicative state of the cell and it may play a role in cell proliferation.
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    Ítem
    Genomic organization of the rDNA cistron of the teleost fish Cyprinus carpio
    (Sociedad de Biología de Chile, 2003) Vera, María Inés; Molina, Alfredo; Pinto, Rodrigo; Reyes, Mauricio; Álvarez, Marco; Krauskopf, Erwin; Quezada, Claudia; Torres, Jorge; Krauskopf, Manuel
    The seasonal adaptation of the teleost Cyprinus carpio to the cyclical changes of its habitat demands physiological compensatory responses. The process involves profound nucleolar adjustments and remarkable changes in rRNA synthesis, which affects ribosomal biosynthesis. In this context, we have demonstrated that the synthesis of several proteins involved in ribosomal biogenesis as protein kinase CK2, ribosomal protein L41 and nucleolin, as well as U3 snoRNP, are differentially regulated in summer-acclimatized carp compared to the cold-season adapted fish. To understand the mechanisms involved in the seasonal regulation of rRNA gene transcription, we have been studying the carp rDNA cistron structure. Because the cis-elements that regulate the expression of the tandem organized ribosomal genes are located in the non-transcribed intergenic spacer (IGS), we analyzed the primary structure of the carp rDNA gene IGS. The gene organization is similar to that described from other vertebrate species, including numerous repetitive sequences, the transcription start site, and some potential cis-elements such as ribosomal enhancers, proximal terminator and transcriptional terminators. Ribosomal DNA is a remarkable case of gene duplication and has been used as a model to test the concerted evolution theory. We performed sequence comparison analyses of 18S rRNA coding sequences from carp with different species, data with which an unrooted phylogram was constructed.