Rossana Arroyo

Publications (61) View all

• Source

  Available from: Rossana Arroyo

  Article: Identification of two novel Trichomonas vaginalis eif-5a genes.

  B Carvajal-Gamez, R Arroyo, R Lira, C López-Camarillo, M E Alvarez-Sánchez
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  ABSTRACT: The eukaryotic translation initiation factor 5A (eIF-5A) is highly conserved and is the only protein that is known to contain the unique and essential amino acid residue hypusine. Synthesis of hypusine is essential for the function of eIF5A in eukaryotic cell proliferation and survival. In this study, we identified two novel eukaryotic translation initiation factor 5A (eIF-5A) genes in Trichomonas vaginalis. The tveif-5a1 and tveif-5a2 putative genes were localized in different contigs, both containing ORFs encoding proteins of 168 amino acids that share high sequence identity with eIF-5A sequences from other eukaryotic organisms. A phylogenetic tree constructed with TveIF-5A1 and TveIF-5A2 from T. vaginalis and 13 other eIF-5A sequences of eukaryotic and archaebacterial origin revealed that both trichomonal TveIF-5As show the highest degree of similarity to bacteria. Using an anti-TveIF-5A antibody, we detected two protein bands and spots of 19 and 20kDa with isoelectric points (pI) of 5.2 and 5.5, respectively, by one and two-dimensional Western blot assays. In addition, we used reverse transcription polymerase chain reaction (RT-PCR) to demonstrate that both of these tveif-5a genes are expressed in T. vaginalis. Immunofluorescence assays showed that the TveIF-5A protein was dispersed throughout the parasite cytoplasm. In conclusion, T. vaginalis has two eif-5a genes, and both genes are expressed as highly conserved proteins of 19kDa, which are localized in the cytoplasm of this parasite.
  Infection, genetics and evolution: journal of molecular epidemiology and evolutionary genetics in infectious diseases 03/2010; 10(2):284-91. · 3.22 Impact Factor
• Article: Responsiveness of Trichomonas vaginalis to iron concentrations: evidence for a post-transcriptional iron regulation by an IRE/IRP-like system.

  J C Torres-Romero, R Arroyo
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  ABSTRACT: Trichomonas vaginalis has high iron-dependency, favoring its growth and multiplication in culture. Iron also regulates some of the trichomonal virulence properties by yet unknown mechanisms. Iron is an essential but potentially toxic metal for the majority of organisms. Thus, its concentration must be tightly regulated within the cell. In mammals, the iron homeostasis is mainly regulated at the post-transcriptional level by a well known mechanism mediated by the binding of iron regulatory proteins (IRP1 and IRP2) to hairpin-loop structures, dubbed iron-responsive elements (IREs), localized in the untranslated regions (UTRs) of target mRNAs. The knowledge of iron regulation in T. vaginalis is still very limited. An iron-responsive promoter and other regulatory elements in the 5'-UTR of the ap65-1 gene were identified as a mechanism for the positive transcriptional regulation of trichomonad genes by iron. Recently, two IRE-like hairpin-loop structures in mRNAs of differentially iron-regulated TVCP4 and TVCP12 cysteine proteinases, as well as IRP-like trichomonad proteins were identified in T. vaginalis, suggesting the existence in this protozoan of a post-transcriptional iron regulatory mechanism by an IRE/IRP-like system. The responsiveness of T. vaginalis to distinct iron concentrations was examined here. Also, the comparison of the atypical IRE-like sequences of T. vaginalis with the consensus IRE and other putative IRE sequences present in parasite and bacteria mRNAs suggest that these trichomonad IRE-like sequences might be the ancestral forms of the RNA stem-loop structures of the IRE/IRP system.
  Infection, genetics and evolution: journal of molecular epidemiology and evolutionary genetics in infectious diseases 07/2009; 9(6):1065-74. · 3.22 Impact Factor
• Source

  Available from: Lorena Lopez

  Article: Differences between coding and non-coding regions in the Trichomonas vaginalis genome: an actin gene as a locus model(1).

  N Espinosa, R Hernández, L López-Griego, R Arroyo, I López-Villaseñor
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  ABSTRACT: The sequence of a cloned genomic fragment of Trichomonas vaginalis containing a complete actin gene was determined. An uninterrupted open reading frame of 1128 nucleotides was found that codes for an actin gene. Two overlapped consensus promoter sequences for T. vaginalis were found 12 nucleotides upstream the actin initiation codon. In addition to actin, two incomplete open reading frames were found at the 5' and 3' ends of the clone. These two sequences are expressed and showed similarity to adenylate cyclase genes and a yeast hypothetical protein. The overall sequence showed a higher G+C content and a lower frequency of repeated sequences in the coding regions when compared with the non-coding regions. A similar unequal nucleotide distribution was found in various T. vaginalis genes retrieved from data bases.
  Acta Tropica 03/2001; 78(2):147-54. · 2.72 Impact Factor
• Article: Trichomonas vaginalis: chromatin and mitotic spindle during mitosis.

  E Gómez-Conde, R Mena-López, P Hernández-Jaúregui, M González-Camacho, R Arroyo
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  ABSTRACT: The mitotic phases and the changes that the chromatin and mitotic microtubules undergo during mitosis in the sexually transmitted parasite Trichomonas vaginalis are described. Parasites arrested in the gap 2 phase of the cell cycle by nutrient starvation were induced to mitosis by addition of fresh whole medium. [(3)H] Thymidine labeling of trichomonad parasites for 24 h showed that parasites have at least four synchronic duplications after mitosis induction. Fixed or live and acridine orange (AO)-stained trichomonads analyzed at different times during mitosis by epifluorescence microscopy showed that mitosis took about 45 min and is divided into five stages: prophase, metaphase, early and late anaphase, early and late telophase, and cytokinesis. The AO-stained nucleus of live trichomonads showed green (DNA) and orange (RNA) fluorescence, and the nucleic acid nature was confirmed by DNase and RNase treatment, respectively. The chromatin appeared partially condensed during interphase. At metaphase, it appeared as six condensed chromosomes, as recently reported, which decondensed at anaphase and migrated to the nuclear poles at telophase. In addition, small bundles of microtubules (as hemispindles) were detected only in metaphase with the polyclonal antibody anti-Entamoeba histolytica alpha-tubulin. This antibody showed that the hemispindle and an atractophore-like structure seem to duplicate and polarize during metaphase. In conclusion, T. vaginalis mitosis involves five mitotic phases in which the chromatin undergoes different degrees of condensation, from chromosomes to decondensed chromatin, and two hemispindles that are observed only in the metaphase stage.
  Experimental Parasitology 12/2000; 96(3):130-8. · 2.12 Impact Factor
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  Available from: María Elizbeth Alvarez-Sánchez

  Article: A novel cysteine proteinase (CP65) of Trichomonas vaginalis involved in cytotoxicity.

  M E Alvarez-Sánchez, L Avila-González, C Becerril-García, L V Fattel-Facenda, J Ortega-López, R Arroyo
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  ABSTRACT: The goal of this study was to demonstrate the participation in cellular damage of a Trichomonas vaginalis proteinase with a molecular mass of 65 kDa (CP65). By two dimensional gelatin-gel electrophoresis of trichomonad proteins we detected four spots with proteolytic activity on the 65 kDa region, but only one, pI 7.2, binds to the HeLa cell surface. By indirect immunofluorescence, rabbit antibodies against this proteinase localized the CP65 on the plasma membrane and in the cytoplasm of T. vaginalis. Pretreatment of parasites with the specific anti-CP65 antibody reduced trichomonal cytotoxicity to HeLa cell monolayers. The specific cysteine proteinase inhibitor, L-3-carboxy-2, 3-trans-epoxypropionyl-leucylamido (4-guanidino) butane (E64) abrogated the proteinase activity and reduced cytotoxicity levels of T. vaginalis in cell culture monolayers, indicating that the trichomonad CP65 is a cysteine proteinase. Activity of the CP65 proteinase was optimal at pH 5.5 and 37 degrees C, conditions similar to those of patients with trichomonosis. Also, this proteinase degraded some of the proteins found in the vagina, i.e. collagen IV and fibronectin, but not laminin-1 or haemoglobin. Finally, immunoprecipitation assays showed that sera and vaginal washes from trichomonosis patient possess anti-CP65 antibodies. In conclusion, results presented in this work demonstrate that the CP65 is a surface cysteine proteinase involved in T. vaginalis cytotoxicity to HeLa cell monolayers, as a virulence factor. It is immunogenic during human infection and degrades some extracellular matrix proteins, i.e. collagen IV and fibronectin.
  Microbial Pathogenesis 05/2000; 28(4):193-202. · 1.94 Impact Factor