Mechanisms involved in the generation of chromosome rearrangements and aneuploidy in Trypanosoma cruzi exposed to ionizing radiation

Abstract

The induction of DSB (Double Strand Break) on the double strand of DNA by means of ionizing radiation is a useful tool to investigate genetic recombination events in eukaryotes. Mechanisms of repair by DSB contribute to genomic plasticity and may play an important role in chromosomal polymorphism and rearrangements in fungi and protozoa. Our objective is to study the repair of DSB induced by ionizing radiation in T. cruzi and its role in generating genetic diversity observed in different strains and strains of the parasite. In addition, we will investigate the effects of ionizing radiation on T. cruzi virulence in mice. We follow the steps below for achieving these goals: 1) to analyze the effects of ionizing radiation on the molecular karyotype and gene synteny in T. cruzi by hybridization of chromosomal bands separated by Pulsed Field Gel Electrophoresis (PFGE) with chromosome-specific markers. We will select clones (CL Brener) obtained by treatment of the parasite with different doses (100, 250 and 500 Gy) of gamma ionizing radiation. Karyotype changes involving chromosomal regions e100 kb (macroalterations) will be identified by this procedure; 2) to identify chromosomal changes by comparative genomic hybridization based on DNA microarrays (aCGH). aCGH will be used for global mapping and detection of genomic changes induced by gamma radiation. Clones showing chromosomal rearrangements will be examined for chromosomal ploidy (monosomy and polysomia); 3) the virulence of T. cruzi clones with chromosomal rearrangements will be investigated by infection of mice. In this way we intend to obtain new information on the generation of the genetic diversity observed in the different strains and strains of the parasite. (AU)