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BACKGROUND Trypanosoma cruzi is an important protozoan parasite and the causative agent of Chagas disease. A critical step in understanding T. cruzi biology is the study of cellular and molecular features exhibited during its growth curve.OBJECTIVES We aimed to acquire a global view of the gene expression profile of T. cruzi during epimastigote growth.METHODS RNA-Seq analysis of total and polysomal/granular RNA fractions was performed along the 10 days T. cruzi epimastigote growth curve in vitro, in addition to cell viability and cell cycle analyses. We also analysed the polysome profile and investigated the presence of granular RNA by FISH and western blotting.FINDINGS We identified 1082 differentially expressed genes (DEGs), of which 220 were modulated in both fractions. According to the modulation pattern, DEGs were grouped into 12 clusters and showed enrichment of important gene ontology (GO) terms. Moreover, we showed that by the sixth day of the growth curve, polysomal content declined greatly and the RNA granules content appeared to increase, suggesting that a portion of mRNAs isolated from the sucrose gradient during late growth stages was associated with RNA granules and not only polyribosomes. Furthermore, we discuss several modulated genes possibly involved in T. cruzi growth, mainly during the stationary phase, such as genes related to cell cycle, pathogenesis, metabolic processes and RNA-binding proteins.

Background Kinetoplastids are a flagellated group of protists, including some parasites, such as Trypanosoma and Leishmania species, that can cause diseases in humans and other animals. The genomes of these species enclose a fraction of retrotransposons including VIPER and TATE , two poorly studied transposable elements that encode a tyrosine recombinase (YR) and were previously classified as DIRS elements. This study investigated the distribution and evolution of VIPER and TATE in kinetoplastids to understand the relationships of these elements with other retrotransposons. Results We observed that VIPER and TATE have a discontinuous distribution among Trypanosomatidae, with several events of loss and degeneration occurring during a vertical transfer evolution. We were able to identify the terminal repeats of these elements for the first time, and we showed that these elements are potentially active in some species, including T. cruzi copies of VIPER . We found that VIPER and TATE are strictly related elements, which were named in this study as VIPER-like . The reverse transcriptase (RT) tree presented a low resolution, and the origin and relationships among YR groups remain uncertain. Conversely, for RH, VIPER-like grouped with Hepadnavirus , whereas for YR, VIPER-like sequences constituted two different clades that are closely allied to Crypton . Distinct topologies among RT, RH and YR trees suggest ancient rearrangements/exchanges in domains and a modular pattern of evolution with putative independent origins for each ORF. Conclusions Due to the presence of both elements in Bodo saltans, a nontrypanosomatid species, we suggested that VIPER and TATE have survived and remained active for more than 400 million years or were reactivated during the evolution of the host species. We did not find clear evidence of independent origins of VIPER-like from the other YR retroelements, supporting the maintenance of the DIRS group of retrotransposons. Nevertheless, according to phylogenetic findings and sequence structure obtained by this study and other works, we proposed separating DIRS elements into four subgroups: DIRS-like, PAT-like, Ngaro-like, and VIPER-like. Electronic supplementary material The online version of this article (10.1186/s13100-019-0175-2) contains supplementary material, which is available to authori...

Ecto-Nucleoside Triphosphate Diphosphohydrolases are enzymes that hydrolyze tri-and/or diphosphate nucleosides. Evidences pointed out to their participation in Trypanosoma cruzi virulence, infectivity, and purine acquisition. In this study, recombinant T. cruzi knocking out or overexpressing the TcNTPDase-1 gene were built, and the role of TcNTPDase-1 in the in vitro interaction with VERO cells was investigated. Results show that epimastigote forms of hemi-knockout parasites showed about 50% lower level of TcNTPDase-1 gene expression when compared to the wild type, while the T. cruzi overexpressing this gene reach 20 times higher gene expression. In trypomastigote forms, the same decreasing in TcNTPDase-1 gene expression was observed to the hemi-knockout parasites. The in vitro infection assays showed a reduction to 51.6 and 59.9% at the adhesion and to 25.2 and 26.4% at the endocytic indexes to the parasites knockout to one or other allele (Hygro and Neo hemiknockouts), respectively. In contrast, the infection assays with T. cruzi overexpressing TcNTPDase-1 from the WT or Neo hemi-knockout parasites showed an opposite result, with the increasing to 287.7 and 271.1% at the adhesion and to 220.4 and 186.7% at the endocytic indexes, respectively. The parasitic load estimated in infected VERO cells by quantitative real time PCR corroborated these findings. Taken together, the partial silencing and overexpression of the TcNTPDase-1 gene generated viable parasites with low and high infectivity rates, respectively, corroborating that the enzyme encoded for this gene plays an important role to the T. cruzi infectivity.