Rhodnius prolixus not only has served as a model organism for the study of insect physiology, but also is a major vector of Chagas disease, an illness that affects approximately seven million people worldwide. We sequenced the genome of R. prolixus, generated assembled sequences covering 95% of the genome (∼702 Mb), including 15,456 putative protein-coding genes, and completed comprehensive genomic analyses of this obligate blood-feeding insect. Although immune-deficiency (IMD)-mediated immune responses were observed, R. prolixus putatively lacks key components of the IMD pathway, suggesting a reorganization of the canonical immune signaling network. Although both Toll and IMD effectors controlled intestinal microbiota, neither affected Trypanosoma cruzi, the causal agent of Chagas disease, implying the existence of evasion or tolerance mechanisms. R. prolixus has experienced an extensive loss of selenoprotein genes, with its repertoire reduced to only two proteins, one of which is a selenocysteine-based glutathione peroxidase, the first found in insects. The genome contained actively transcribed, horizontally transferred genes from Wolbachia sp., which showed evidence of codon use evolution toward the insect use pattern. Comparative protein analyses revealed many lineage-specific expansions and putative gene absences in R. prolixus, including tandem expansions of genes related to chemoreception, feeding, and digestion that possibly contributed to the evolution of a blood-feeding lifestyle. The genome assembly and these associated analyses provide critical information on the physiology and evolution of this important vector species and should be instrumental for the development of innovative disease control methods.

The multidrug-resistant (MDR) phenotype is multifactorial, and cell lines presenting multiple resistance mechanisms might be good models to understand the importance of the various pathways involved. The present work characterized a MDR chronic myeloid leukemia cell line, derived from K562 through a selective process using daunorubicin. This MDR cell line was shown to be resistant to vincristine, daunorubicin, and partially resistant to imatinib. It showed a slower duplication rate. Overexpression of ABCB1 and ABCC1 was observed at the protein and functional levels and the expression of CD95, a molecule related to cell death, was reduced in the MDR cell line. Conversely, no differences were observed related to the anti-apoptotic molecule Bcl-2 or p53 expression. The activation antigen CD69 was reduced in the MDR cell line and treatment with imatinib further decreased the expressed levels. Furthermore, secretion of IL-8 was diminished in the MDR cell line. When daunorubicin-selected cells were compared to another MDR cell line, Lucena 1, derived from the same parental line K562, and selected with vincristine, a different profile was observed in relation to most aspects studied. When both cell lines were silenced for ABCB1, differences in CD69 and CD95 were maintained, despite resistance reversal. These results reinforce the idea that cell lines selected in vitro may display multiple resistance strategies that may vary with the selective agent used as well as during different steps of the selection process.

Trypanosoma brucei, the etiologic agent of sleeping sickness, encodes a single intron-containing tRNA, tRNA Tyr , and splicing is essential for its viability. In Archaea and Eukarya, tRNA splicing requires a series of enzymatic steps that begin with intron cleavage by a tRNA-splicing endonuclease and culminates with joining the resulting tRNA exons by a splicing tRNA ligase.Here we explored the function of TbTrl1, the T. brucei homolog of the yeast Trl1 tRNA ligase. We used a combination of RNA interference and molecular biology approaches to show that down-regulation of TbTrl1 expression leads to accumulation of intron-containing tRNA Tyr and a concomitant growth arrest at the G1 phase. These defects were efficiently rescued by expression of an "intronless" version of tRNA Tyr in the same RNAi cell line. Taken together, these experiments highlight the crucial importance of the TbTrl1 for tRNA Tyr maturation and viability, while revealing tRNA splicing as its only essential function.

All organisms encode transfer RNAs (tRNAs) that are synthesized as precursor molecules bearing extra sequences at their 5′ and 3′ ends; some tRNAs also contain introns, which are removed by splicing. Despite commonality in what the ultimate goal is (i.e., producing a mature tRNA), mechanistically, tRNA splicing differs between Bacteria and Archaea or Eukarya. The number and position of tRNA introns varies between organisms and even between different tRNAs within the same organism, suggesting a degree of plasticity in both the evolution and persistence of modern tRNA splicing systems. Here we will review recent findings that not only highlight nuances in splicing pathways but also provide potential reasons for the maintenance of introns in tRNA. Recently, connections between defects in the components of the tRNA splicing machinery and medically relevant phenotypes in humans have been reported. These differences will be discussed in terms of the importance of splicing for tRNA function and in a broader context on how tRNA splicing defects can often have unpredictable consequences.