title: Kinetoplast adaptations in American strains from Trypanosoma vivax.
abstract: The mitochondrion role changes during the digenetic life cycle of African trypanosomes. Owing to the low abundance of glucose in the insect vector (tsetse flies) the parasites are dependent upon a fully functional mitochondrion, capable of performing oxidative phosphorylation. Nevertheless, inside the mammalian host (bloodstream forms), which is rich in nutrients, parasite proliferation relies on glycolysis, and the mitochondrion is partially redundant. In this work we perform a comparative study of the mitochondrial genome (kinetoplast) in different strains of Trypanosoma vivax. The comparison was conducted between a West African strain that goes through a complete life cycle and two American strains that are mechanically transmitted (by different vectors) and remain as bloodstream forms only. It was found that while the African strain has a complete and apparently fully functional kinetoplast, the American T. vivax strains have undergone a drastic process of mitochondrial genome degradation, in spite of the recent introduction of these parasites in America. Many of their genes exhibit different types of mutations that are disruptive of function such as major deletions, frameshift causing indels and missense mutations. Moreover, all but three genes (A6-ATPase, RPS12 and MURF2) are not edited in the American strains, whereas editing takes place normally in all (editable) genes from the African strain. Two of these genes, A6-ATPase and RPS12, are known to play an essential function during bloodstream stage. Analysis of the minicircle population shows that its diversity has been greatly reduced, remaining mostly those minicircles that carry guide RNAs necessary for the editing of A6-ATPase and RPS12. The fact that these two genes remain functioning normally, as opposed to that reported in Trypanosoma brucei-like trypanosomes that restrict their life cycle to the bloodstream forms, along with other differences, is indicative that the American T. vivax strains are following a novel evolutionary pathway.
authors.affiliation: Unidad de Biología Molecular, Institut Pasteur de Montevideo, Uruguay.
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Greif
authors.affiliation: Sección Biomatemática, Facultad de Ciencias, Universidad de la Republica, Uruguay.
authors.forename: Matías
authors.initials: M
authors.lastname: Rodriguez
authors.affiliation: Departamento de Ciencias de la Vida, Carrera en Ingeniería en Biotecnología, Universidad de las Fuerzas Armadas, Ecuador; Centro de Estudios Biomédicos y Veterinarios, Universidad Nacional Experimental Simón Rodríguez-IDECYT, Caracas, Venezuela.
authors.forename: Armando
authors.initials: A
authors.lastname: Reyna-Bello
authors.affiliation: Unidad de Biología Molecular, Institut Pasteur de Montevideo, Uruguay; Departamento de Bioquímica, Facultad de Medicina, Universidad de la República Uruguay.
authors.forename: Carlos
authors.initials: C
authors.lastname: Robello
authors.affiliation: Sección Biomatemática, Facultad de Ciencias, Universidad de la Republica, Uruguay. Electronic address: falvarez@fcien.edu.uy.
authors.forename: Fernando
authors.initials: F
authors.lastname: Alvarez-Valin
mesh_terms: D000222:Adaptation, Physiological; D000251:Adenosine Triphosphatases / Q000235:genetics; D000595:Amino Acid Sequence; D018105:DNA, Kinetoplast / Q000502:physiology*; D018503:Genome, Protozoan; D008928:Mitochondria / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D017393:RNA Editing; D016689:Trypanosoma vivax / Q000235:genetics*
chemical_list: D018105:DNA, Kinetoplast; D000251:Adenosine Triphosphatases
keywords: Editing; Fast evolution; Genome degradation; Mechanical transmission