Examinando por Autor "Pinto, R."

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    A putative RNA editing from U to C in a mouse mitochondrial transcript
    (Oxford University Press, 2002-05) Villegas, J.; Müller, I.; Arredondo, J.; Pinto, R.; Burzio, L.O.
    Recently, we isolated and characterized a new mouse mitochondrial RNA molecule containing the mitochondrial 16S RNA plus 121 nt joined to the 5′ end of the RNA. This fragment arises from the L strand of the same gene and we have named this transcript chimeric RNA. At position 121 of the RNA there is a C, which, according to the sequence of the mitochondrial 16S RNA gene, should be a U. We hypothesized that this RNA is synthesized having a U at position 121, which is later substituted to a C by a putative editing reaction. Based on the presence of sites for the restriction endonucleases RsaI and Fnu4HI around position 121, both forms of the RNA were detected in mouse tissues. To confirm the presence of the non-edited and putative edited RNA, a fragment containing the first 154 nt of the RNA was amplified by RT–PCR and cloned. The substitution of U for C was demonstrated by sequencing these clones. In vitro transcription experiments demonstrated that the substitution of U for C is not due to artifact of amplification or cloning. Moreover, in mitochondria from testis only the non-edited form was found. This, together with other experimental evidence, demonstrated that the base substitution was not due to polymorphism of the mitochondrial 16S RNA gene. This is the first demonstration of a substitution reaction from U to C in a mammalian mitochondrial transcript.
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    Seasonal environmental changes regulate the expression of the histone variant macroH2A in an eurythermal fish
    (Elsevier [Former Publisher] Federation of European Biochemical Societies [Associate Organisation] Wiley [Commercial Publisher], 2005-10) Pinto, R.; Ivaldi, C.; Reyes, M.; Doyen, C.; Mietton, F.; Mongelard, F.; Alvarez, M.; Molina, A.; Dimitrov, S.; Krauskopf, M.; Vera, M.; Bouvet, P.
    Adaptation to cold and warm conditions requires dramatic change in gene expression. The acclimatization process of the common carp Cyprinus carpio L. in its natural habitat has been used to study how organisms respond to natural environmental changes. At the cellular level, adaptation to cold condition is accompanied by a dramatic alteration in nucleolar structure and a down regulation of the expression of ribosomal genes. We show that the enrichment of condensed chromatin in winter adapted cells is not correlated with an increase of the heterochromatin marker trimethyl and monomethyl K20H4. However, the expression of the tri methyl K4 H3 and of the variant histone macroH2A is significantly increased during the winter season together with a hypermethylation of CpG residues. Taking into account the properties of macroH2A toward chromatin structure and dynamics and its role in gene repression our data suggest that the increased expression of macroH2A and the hypermethylation of DNA which occurs upon winter-acclimatization plays a major role for the reorganization of chromatin structure and the regulation of gene expression during the physiological adaptation to a colder environment.