Assessment of genetic mutation frequency induced by oxidative stress in Trypanosoma cruzi

Abstract

Trypanosoma cruzi is the etiological agent of Chagas disease, a public health challenge due to its morbidity and mortality rates, which affects around 6-7 million people worldwide. Symptoms, response to chemotherapy, and the course of Chagas disease are greatly influenced by T. cruzi‘s intra-specific variability. Thus, DNA mutations in this parasite possibly play a key role in the wide range of clinical manifestations and in drug sensitivity. Indeed, the environmental conditions of oxidative stress faced by T. cruzi during its life cycle can generate genetic mutations. However, the lack of an established experimental design to assess mutation rates in T. cruzi precludes the study of conditions and mechanisms that potentially produce genomic variability in this parasite. We developed an assay that employs a reporter gene that, once mutated in specific positions, convert G418-sensitive into G418-insenstitive T. cruzi. We were able to determine the frequency of DNA mutations in T. cruzi exposed and non-exposed to oxidative insults assessing the number of colony-forming units in solid selective media after plating a defined number of cells. We verified that T. cruzi‘s spontaneous mutation frequency was comparable to those found in other eukaryotes, and that exposure to hydrogen peroxide promoted a two-fold increase in T. cruzi‘s mutation frequency. We hypothesize that genetic mutations in T. cruzi can arise from oxidative insults faced by this parasite during its life cycle.

Trypanosoma brucei and Trypanosoma cruzi DNA Mismatch Repair Proteins Act Differently in the Response to DNA Damage Caused by Oxidative Stress

“…Long-term cultivation of T. cruzi induces mutational events. This frequency is increased when parasites are cultivated in sub-lethal doses of H 2 O 2 (Torres-Silva et al, 2018). In trypanosomatids, MMR proteins might have an additional role in recognizing DNA oxidative damage and act as signaling molecules.…”

Transcription activity contributes to the firing of non-constitutive origins in Trypanosoma brucei

“…It is worth mentioning that, as a group, trypanosomatids emerged late on the evolutionary scale and are one of the most successful groups of specialist parasites on earth (14,79,80). This success probably occurred because these organisms proliferate rapidly, which increases the onset of mutation frequency due to multiple DNA replication events in a relatively short period (81)(82)(83).…”

Diversity and interactions among triatomine bugs, their blood feeding sources, gut microbiota and Trypanosoma cruzi in the Sierra Nevada de Santa Marta in Colombia

“…Mini-exon sequences from multiple TcI strains from across the Americas were then used for further comparison (Supplementary Table S1 ). TcI sequences were analyzed in Beast 2.6.2 64 and the best model based on Akaike information criteria was based on a HKY substitution model for a constant coalescent population, and the molecular clock was set based on substitution frequency of 7.1 × 10 –8 as previously established for T. cruzi 65 . The model was run for 10 million iterations to obtain the maximum credibility tree.…”