Dynamic S-palmitoylation of proteins is the addition of palmitic acid by zDHHC palmitoyl transferases (PATs) and depalmitoylation by palmitoyl protein thioesterases (PPTs). A putative PAT (TcPAT1) has been previously identified in Trypanosoma cruzi, the etiological agent of Chagas disease. Here we analyse other 14 putative TcPATs and 2 PPTs in the parasite genome. T. cruzi cell lines expressing TcPATs and TcPPTs plus a FLAG tag at the C terminus were produced for most enzymes, with positive detection by indirect immunofluorescence. Overexpressed TcPATs were mostly found as single spots at the parasite anterior end, while the TcPPTs were dispersed throughout the parasite body.

BACKGROUND Recent studies showed that essential oils from different pepper species (Piper spp.) have promising leishmanicidal and trypanocidal activities. OBJECTIVES In search for natural compounds against Trypanosoma cruzi, different forms of the parasite were incubated for 24 h at 28ºC or 4ºC with Piper aduncum essential oil (PaEO) or its main constituents linalool and nerolidol. METHODS PaEO chemical composition was obtained by GC-MS. Drug activity assays were based on cell counting, MTT data or infection index values. The effect of PaEO on the T. cruzi cell cycle and mitochondrial membrane potential was evaluated by flow cytometry. FINDINGS PaEO was effective against cell-derived (IC50/24 h: 2.8 μg/mL) and metacyclic (IC50/24 h: 12.1 μg/mL) trypomastigotes, as well as intracellular amastigotes (IC50/24 h: 9 μg/mL). At 4ºC - the temperature of red blood cells (RBCs) storage in blood banks - cell-derived trypomastigotes were more sensitive to PaEO (IC50/24 h = 3.8 μg/mL) than to gentian violet (IC50/24 h = 24.7 mg/mL). Cytotoxicity assays using Vero cells (37ºC) and RBCs (4ºC) showed that PaEO has increased selectivity for cell-derived trypomastigotes. Flow cytometry analysis showed that PaEO does not affect the cell cycle of T. cruzi epimastigotes, but decreases their mitochondrial membrane potential. GC-MS data identified nerolidol and linalool as major components of PaEO, and linalool had trypanocidal effect (IC50/24 h: 306 ng/mL) at 4ºC. MAIN CONCLUSION The trypanocidal effect of PaEO is likely due to the presence of linalool, which may represent an interesting candidate for use in the treatment of potentially contaminated RBCs bags at low temperature.

This study had analyzed the antibacterial, antifungal and trypanocidal activity of the essential oils from Cinnamodendron dinisii Schwacke (Canellaceae) and Siparuna guianensis Aublet (Siparunaceae). The essential oils were obtained from fresh leaves by hydrodistillation, using a modified Clevenger apparatus. Chemical analysis by gas-liquid chromatography coupled to mass spectrometry (GC-MS) showed that these essential oils are rich in monoterpene and sesquiterpene hydrocarbons. Activity against the pathogenic bacteria Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa, Salmonella choleraesuis and Staphylococcus aureus was evaluated with the agar cavity diffusion method, while activity on the filamentous fungi Aspergillus flavus, Aspergillus niger, Aspergillus carbonariusand Penicillium commune was evaluated by the disk diffusion technique. Trypanocidal activity was tested against Trypanosoma cruzi epimastigotes, using the Tetrazolium salt (MTT) colorimetric assay. Both essential oils exhibited low inhibitory effect towards bacteria, showing high MIC values (125–500 μg mL−1), with Gram positive bacteria being more susceptible. Better inhibitory effect was obtained for the evaluated fungi, with lower MIC values (7.81–250 μg mL−1), being A. flavus the most susceptible species. Both essential oils presented low trypanocidal activity, with IC50/24 h values of 209.30 μg mL−1 for S. guianensis and 282.93 μg mL−1 for C. dinisii. Thus, the high values observed for the MIC of evaluated bacteria and for IC50/24 h of T. cruzi, suggest that the essential oils have a low inhibitory activity against these microorganisms. In addition, the low MIC values observed for the tested fungi species indicate good inhibitory activity on these microorganisms’s growth.

Heteroxenic and monoxenic trypanosomatids were screened for the presence of actin using a mouse polyclonal antibody produced against the entire sequence of the Trypanosoma cruzi actin gene, encoding a 41.9 kDa protein. Western blot analysis showed that this antibody reacted with a polypeptide of approximately 42 kDa in the whole-cell lysates of parasites targeting mammals (T. cruzi, Trypanosoma brucei and Leishmania major), insects (Angomonas deanei, Crithidia fasciculata, Herpetomonas samuelpessoai and Strigomonas culicis) and plants (Phytomonas serpens). A single polypeptide of approximately 42 kDa was detected in the whole-cell lysates of T. cruzi cultured epimastigotes, metacyclic trypomastigotes and amastigotes at similar protein expression levels. Confocal microscopy showed that actin was expressed throughout the cytoplasm of all the tested trypanosomatids. These data demonstrate that actin expression is widespread in trypanosomatids.

Trypanosomes are parasitic protozoa in which gene expression is primarily controlled through the regulation of mRNA stability and translation. This post-transcriptional control is mediated by various families of RNA-binding proteins, including those with zinc finger CCCH motifs. CCCH zinc finger proteins have been shown to be essential to differentiation events in trypanosomatid parasites. Here, we functionally characterise TcZFP2 as a predicted post-transcriptional regulator of differentiation in Trypanosoma cruzi. This protein was detected in cell culture-derived amastigotes and trypomastigotes, but it was present in smaller amounts in metacyclic trypomastigote forms of T. cruzi. We use an optimised recombinant RNA immunopreciptation followed by microarray analysis assay to identify TcZFP2 target mRNAs. We further demonstrate that TcZFP2 binds an A-rich sequence in which the adenosine residue repeats are essential for high-affinity recognition. An analysis of the expression profiles of the genes encoding the TcZFP2-associated mRNAs throughout the parasite life cycle by microarray hybridisation showed that most of the associated mRNAs were upregulated in the metacyclic trypomastigote forms, also suggesting a role for TcZFP2 in metacyclic trypomastigote differentiation. Knockdown of the orthologous Trypanosoma brucei protein levels showed ZFP2 to be a positive regulator of specific target mRNA abundance.

Citral, the main constituent of lemongrass (Cymbopogon citratus) essential oil, was added to Trypanosoma cruzi cultures grown in TAU3AAG medium to observe the effect on the epimastigote-to-trypomastigote differentiation process (metacyclogenesis). Our results showed that citral (20 μg/mL) did not affect epimastigote viability or inhibit the differentiation process. Concentrations higher than 60 μg/mL, however, led to 100% cell death (both epimastigote and trypomastigote forms). Although epimastigotes incubated with 30 μg/mL citral were viable and able to adhere to the substrate, we observed around 50% inhibition in metacyclogenesis, with a calculated concentration that inhibited metacyclogenesis by 50% after 24 h (IC50/24 h) of about 31 μg/mL. Treatment with 30 μg/mL citral did not hinder epimastigote multiplication because epimastigote growth resumed when treated cells were transferred to a drug-free liver infusion tryptose culture medium. Metacyclogenesis was almost totally abolished at 40 μg/mL after 24 h of incubation. Furthermore, the metacyclic trypomastigotes obtained in vitro were similarly susceptible to citral, with an IC50/24 h, concentration that killed 50% of the cells after 24 h, of about 24.5 μg/mL. Therefore, citral appears to be a good candidate as an inhibitory drug for further studies analyzing the T. cruzi metacyclogenesis process.

Here we report the subcellular localization of an intracellular serine protease of 68 kDa in axenic promastigotes of Leishmania (Leishmania) amazonensis, using subcellular fractionation, enzymatic assays, immunoblotting, and immunocytochemistry. All fractions were evaluated by transmission electron microscopy and the serine protease activity was measured during the cell fractionation procedure using a-N-r-tosyl-L-arginine methyl ester (L-TAME) as substrate, phenylmethylsulphone fluoride (PMSF) and L-1-tosylamino-2-phenylethylchloromethylketone (TPCK) as specific inhibitors. The enzymatic activity was detected mainly in a membranous vesicular fraction (6.5-fold enrichment relative to the whole homogenate), but also in a crude plasma membrane fraction (2.0-fold). Analysis by SDS-PAGE gelatin under reducing conditions demonstrated that the major proteolytic activity was found in a 68 kDa protein in all fractions studied. A protein with identical molecular weight was also recognized in immunoblots by a polyclonal antibody against serine protease (anti-SP), with higher immunoreactivity in the vesicular fraction. Electron microscopic immunolocalization using the same polyclonal antibody showed the enzyme present at the cell surface, as well as in cytoplasmic membranous compartments of the parasite. Our findings indicate that the internal location of this serine protease in L. amazonensis is mainly restricted to the membranes of intracellular compartments resembling endocytic/exocytic elements.

Anopheles albitarsis embryogenesis was analyzed through confocal microscopy of clarified eggs. Using Drosophila melanogaster as reference system, the major morphogenetic events (blastoderm, gastrulation, germ band extension, germ band retraction, dorsal closure) were identified. The kinetics of early events is proportionally similar in both systems, but late movements (from germ band retraction on) progress slower in An. albitarsis. Major differences in An. albitarsis related to D. melanogaster were: (1) pole cells do not protrude from the blastoderm; (2) the mosquito embryo undergoes a 180º rotation movement, along its longitudinal axis; (3) the head remains individualized throughout embryogenesis; (4) extraembryonary membranes surround the whole embryo. A novel kind of malaria control is under development and is based on the use of genetically modified mosquitoes. Phenotypic analysis of the embryonic development of mutants will be imposed as part of the evaluation of effectiveness and risk of employment of this strategy in the field. In order to accomplish this, knowledge of the wild type embryo is a prerequisite. Morphological studies will also serve as basis for subsequent development biology approaches.