A nuclear ribosomal DNA pseudogene in triatomines opens a new research field of fundamental and applied implications in Chagas disease

A pseudogene, designated as "ps(5.8S+ITS-2)", paralogous to the 5.8S gene andinternal transcribed spacer (ITS)-2 of the nuclear ribosomal DNA (rDNA), has beenrecently found in many triatomine species distributed throughout North America,Central America and northern South America. Among characteristics used as criteriafor pseudogene verification, secondary structures and free energy are highlighted,showing a lower fit between minimum free energy, partition function and centroidstructures, although in given cases the fit only appeared to be slightly lower. Theunique characteristics of "ps(5.8S+ITS-2)" as a processed or retrotransposedpseudogenic unit of the ghost type are reviewed, with emphasis on its potentialfunctionality compared to the functionality of genes and spacers of the normal rDNAoperon. Besides the technical problem of the risk for erroneous sequence results, theusefulness of "ps(5.8S+ITS-2)" for specimen classification, phylogenetic analyses andsystematic/taxonomic studies should be highlighted, based on consistence andretention index values, which in pseudogenic sequence trees were higher than infunctional sequence trees. Additionally, intraindividual, interpopulational andinterspecific differences in pseudogene amount and the fact that it is a pseudogenein the nuclear rDNA suggests a potential relationships with fitness, behaviour andadaptability of triatomine vectors and consequently its potential utility in Chagasdisease epidemiology and control.