My work broadly concentrates on pre-mRNA metabolism and non-coding RNAs, particularly of protozoan parasites. In the process of uncovering the first molecular karyotype of Entamoeba histolytica and E. invadens, I found evidence of the entamoeba chitin synthase and chitosome components, as well as the protozoan Myc homolog. Due to the lack of biochemical evidence, I set to analyze the distinctive functions of spliceosomal proteins of the parasite. Using various molecular and in vivo expression approaches we have disclosed the mechanisms of core and constitutive spliceosomal proteins that impact splicing of entamoeba introns bearing canonical and non-canonical splicing sites. My interest is focused on the impact of RNA-protein interactions and RNA secondary structure on the splicing outcome and gene expression regulation. I also discovered circular non-coding full-length intronic RNAs (flicRNAs), both nuclear and cytoplasmic, and using in silico data mining exonic circRNAs were also characterized. The evidence suggests that, whereas the nuclear flicRNAs downregulate their parental gene expression in cis, proteomic, metabolomic and ChIP analyses are being conducted to disclose the functions of the remaining circular non-coding RNAs.