- Av. Brasil 4365 P26 S207
Manguinhos
Postal code 21040-360
Rio de Janeiro - RJ - Brazil - +5521-999671335
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Research Interests: Biochemistry, Biology, Digestion, Insects, Enzyme, and 6 moreBioquímica, Dictyoptera, Celulose, Glucanase, Insetos, and Enzima
Triatomine insects had a fundamental role in the establishment of essential concepts of insect physiology, especially thanks to the use of Rhodnius prolixus as a model for basic research in the last century. The major unique feature that... more
Triatomine insects had a fundamental role in the establishment of essential concepts of insect physiology, especially thanks to the use of Rhodnius prolixus as a model for basic research in the last century. The major unique feature that made triatomines excellent models is their strictly hematophagous way of life, as molting in nymph stages and oogenesis in the adult are triggered by a blood meal. Therefore, development and reproduction are strictly controlled in an on/off fashion by the arrival of the voluminous blood meal at the digestive channel. However, these insects are less popular in the science arena due to the scarcity of genetic and molecular data. The last few years, however, have manifested a change in the field due to the appearance of large datasets of genomic, transcriptomic, and phylogenetic molecular information, as well as a series of new methodological advances. Here, we tried to make a brief connection between the classical outline of blood digestion physiology in triatomines and this new science scenario, trying to identify critical information that is still lacking.
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Research Interests: Chemistry and Humanities
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Capillary electrophoresis with capacitively coupled contactless conductivity detection was successfully used to quantify N-acetylglucosamine and five N-acetyl-chitooligosaccharides (C2-C6) produced after reaction with a purified chitinase... more
Capillary electrophoresis with capacitively coupled contactless conductivity detection was successfully used to quantify N-acetylglucosamine and five N-acetyl-chitooligosaccharides (C2-C6) produced after reaction with a purified chitinase (TmChi) from Tenebrio molitor (Coleoptera). No derivatization process was necessary. The separation was developed using 10 mM NaOH with 10% (v/v) acetonitrile as background electrolyte and homemade equipment with a system that avoids the harmful effect of electrolysis. The limit of detection for all oligosaccharides was ca. 3microM, and the results indicated that the larger the oligosaccharide, the higher the sensitivity. Analysis of the chitooligosaccharides produced revealed that TmChi has an endolytic cleavage pattern with C5 as the best substrate (higher catalytic efficiency kcat/KM) releasing C2 and C3.
Research Interests: Chemistry, Analytical Chemistry, Chromatography, Catalysis, Capillary electrophoresis, and 13 moreSensitivity Analysis, Medicine, Analytical, Derivatization, Chitinase, Biochemistry and molecular biology, Analytical Biochemistry, Biochemistry and cell biology, Oligosaccharides, Tenebrio molitor, Chitinases, capillary zone electrophoresis, and limit of detection
Research Interests: Microbiology, Biology, Biological Chemistry, Leishmania, Medicine, and 15 moreBiological Sciences, Antioxidants, Immunity, Female, Animals, Catalase, CHEMICAL SCIENCES, Hydrogen Peroxide, Gastrointestinal Tract, Host Pathogen Interactions, Amino Acid Sequence, Innate Immune System, Insect Vectors, Molecular Sequence Data, and Medical and Health Sciences
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BACKGROUNDCulex quinquefasciatus resistance to the binary toxin from Lysinibacillus sphaericus larvicides can occur because of mutations in the cqm1 gene that prevents the expression of the toxin receptor, Cqm1 α‐glucosidase. In a... more
BACKGROUNDCulex quinquefasciatus resistance to the binary toxin from Lysinibacillus sphaericus larvicides can occur because of mutations in the cqm1 gene that prevents the expression of the toxin receptor, Cqm1 α‐glucosidase. In a resistant laboratory‐selected colony maintained for more than 250 generations, cqm1REC and cqm1REC‐2 resistance alleles were identified. The major allele initially found, cqm1REC, became minor and was replaced by cqm1REC‐2. This study aimed to investigate the features associated with homozygous larvae for each allele to understand the reasons for the allele replacement and to generate knowledge on resistance to microbial larvicides.RESULTSHomozygous larvae for each allele were compared. Both larvae displayed the same level of resistance to the binary toxin (3500‐fold); therefore, a change in phenotype was not the reason for the replacement observed. The lack of Cqm1 expression did not reduce the total specific α‐glucosidase activity for homozygous cqm1REC ...
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Background Botanical substances such as essential oils (EOs) have demonstrated insecticidal properties and are a valid option for vector control. However, free EOs are unreliable as mosquito larvicides due their easy degradation by... more
Background Botanical substances such as essential oils (EOs) have demonstrated insecticidal properties and are a valid option for vector control. However, free EOs are unreliable as mosquito larvicides due their easy degradation by environmental exposure to ultraviolet light and higher temperatures. Here, we assessed the efficacy of a mosquito larvicide based on orange oil in a yeast-based delivery system against Aedes aegypti strains with different resistance status towards chemical neurotoxic insecticides. This larvicide preparation was physicochemically characterized in a previous report. Methods Larvae of four Ae. aegypti strains from different regions of Brazil and different resistance profiles for deltamethrin (pyrethroid) and temephos (organophosphate) were tested against yeast-encapsulated orange oil (YEOO) in laboratory conditions for measurement of LC50 and LC90 values. The same assays were performed with the Belo Horizonte strain under environmental conditions (natural li...
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The P2X7 receptor is a critical purinergic receptor in immune cells. Its activation was associated with cathepsin release into macrophage cytosol, suggesting its involvement in lysosomal membrane permeabilization (LMP) and leakage.... more
The P2X7 receptor is a critical purinergic receptor in immune cells. Its activation was associated with cathepsin release into macrophage cytosol, suggesting its involvement in lysosomal membrane permeabilization (LMP) and leakage. Nevertheless, the mechanisms by which P2X7 receptor activation induces LMP and leakage are unclear. This study investigated cellular mechanisms associated with endosomal and lysosomal leakage triggered by P2X7 receptor activation. We found that ATP at 500 μM and 5 mM (but not 50 μM) induced LMP in non-stimulated peritoneal macrophages. This effect was not observed in P2X7-deficient or A740003-pretreated macrophages. We found that the P2X7 receptor and pannexin-1 channels mediate calcium influx that might be important for activating specific ion channels (TRPM2 and two-pore channels) on the membranes of late endosomes and lysosomes leading to LMP leakage and consequent cathepsin release. These findings suggest the critical role of the P2X7 receptor in infl...
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Lutzomyia longipalpis is the main vector of visceral leishmaniasis (VL) in America. Physiological and molecular mechanisms of Leishmania infection in sand flies have been studied during the first gonotrophic cycle. There are few studies... more
Lutzomyia longipalpis is the main vector of visceral leishmaniasis (VL) in America. Physiological and molecular mechanisms of Leishmania infection in sand flies have been studied during the first gonotrophic cycle. There are few studies about these interactions during the second gonotrophic cycle mainly because of the difficulties maintaining sand flies through sequential feeds. Here we standardized conditions to perform the second blood feed efficiently, and our results show that oviposition is an essential factor for the success of multiple feeds. We evaluated the impact of the second blood meal on longevity, protein digestion, trypsin activity, and Leishmania mexicana development within L. longipalpis gut. Mortality of blood-fed females increases after second blood meal as compared to sugar-fed females. Trypsin activity was lower during the second gonotrophic cycle. However, no difference in protein intake was observed between blood meals. There was no difference in the populatio...
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Research Interests: Biochemistry, Biology, Medicine, Cathepsin, Rhodnius prolixus, and 3 moreMidgut, proteolysis, and cathepsin L
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The soluble midgut trehalase from Tenebrio molitor (TmTre1) was purified after several chromatographic steps, resulting in an enzyme with 58 kDa and pH optimum 5.3 (ionizing active groups in the free enzyme: pK(e1) = 3.8 ± 0.2 pK(e2) =... more
The soluble midgut trehalase from Tenebrio molitor (TmTre1) was purified after several chromatographic steps, resulting in an enzyme with 58 kDa and pH optimum 5.3 (ionizing active groups in the free enzyme: pK(e1) = 3.8 ± 0.2 pK(e2) = 7.4 ± 0.2). The purified enzyme corresponds to the deduced amino acid sequence of a cloned cDNA (TmTre1-cDNA), because a single cDNA coding a soluble trehalase was found in the T. molitor midgut transcriptome. Furthermore, the mass of the protein predicted to be coded by TmTre1-cDNA agrees with that of the purified enzyme. TmTre1 has the essential catalytic groups Asp 315 and Glu 513 and the essential Arg residues R164, R217, R282. Carbodiimide inactivation of the purified enzyme at different pH values reveals an essential carboxyl group with pKa = 3.5 ± 0.3. Phenylglyoxal modified a single Arg residue with pKa = 7.5 ± 0.2, as observed in the soluble trehalase from Spodoptera frugiperda (SfTre1). Diethylpyrocarbonate modified a His residue that resulted in a less active enzyme with pK(e1) changed to 4.8 ± 0.2. In TmTre1 the modified His residue (putatively His 336) is more exposed than the His modified in SfTre1 (putatively His 210) and that affects the ionization of an Arg residue. The architecture of the active site of TmTre1 and SfTre1 is different, as shown by multiple inhibition analysis, the meaning of which demands further research. Trehalase sequences obtained from midgut transcriptomes (pyrosequencing and Illumina data) from 8 insects pertaining to 5 different orders were used in a cladogram, together with other representative sequences. The data suggest that the trehalase gene went duplication and divergence prior to the separation of the paraneopteran and holometabolan orders and that the soluble trehalase derived from the membrane-bound one by losing the C-terminal transmembrane loop.
Research Interests: Biochemistry, Molecular Evolution, Biology, Medicine, Animals, and 15 moreMolecular Phylogenetics and Evolution, Enzyme, Molecular cloning, Active site, Gastrointestinal Tract, Insect Biochemistry and Molecular Biology, Amino Acid Sequence, Base Sequence, Chemical Modification, cDNA library, Biochemistry and cell biology, Spodoptera litura, Molecular Sequence Data, Midgut, and DPC
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Research Interests: Physiology, Zoology, Molecular Biology, Biology, Insect Physiology, and 15 moreMedicine, Phylogeny, Sequence alignment, Female, Animals, Male, Triatoma, RT PCR, Carboxypeptidases, Amino Acid Sequence, Gene Expression Regulation, Molecular Sequence Data, Midgut, Tissue distribution, and reverse transcriptase polymerase chain reaction
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The major beta-1,3-glucanase from Tenebrio molitor (TLam) was purified to homogeneity (yield, 6%; enrichment, 113 fold; specific activity, 4.4 U/mg). TLam has a molecular weight of 50 kDa and a pH optimum of 6. It is an endoglucanase that... more
The major beta-1,3-glucanase from Tenebrio molitor (TLam) was purified to homogeneity (yield, 6%; enrichment, 113 fold; specific activity, 4.4 U/mg). TLam has a molecular weight of 50 kDa and a pH optimum of 6. It is an endoglucanase that hydrolyzes beta-1,3-glucans as laminarin and yeast beta-1,3-1,6-glucan, but is inactive toward other polysaccharides (as unbranched beta-1,3-glucans or mixed beta-1,3-1,4-glucan from cereals) or disaccharides. The enzyme is not inhibited by high substrate concentrations and has low processivity (0.6). TLam has two ionizable groups involved in catalysis, and His, Tyr and Arg residues plus a divalent ion at the active site. A Cys residue important for TLam activity is exposed after laminarin binding. The cDNA coding for this enzyme was cloned and sequenced. It belongs to glycoside hydrolase family 16, and is related to other insect glucanases and glucan-binding proteins. Sequence analysis and homology modeling allowed the identification of some residues (E174, E179, H204, Y304, R127 and R181) at the active site of the enzyme, which may be important for TLam activity. TLam efficiently lyses fungal cells, suggesting a role in making available walls and cell contents to digestion and in protecting the midgut from pathogen infections.
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Research Interests: Biochemistry, Biology, Medicine, Homology Modeling, Animals, and 15 moreLectins, Gene Duplication, Enzyme, Larva, Gastrointestinal Tract, Molecular Mass, Insect Biochemistry and Molecular Biology, Multiple Sequence Alignment, Amino Acid Sequence, Base Sequence, Glucanase, Biochemistry and cell biology, Molecular Sequence Data, Midgut, and glucan
Research Interests: Biochemistry, Catalysis, Kinetics, Biology, Enzyme Inhibitors, and 15 morePolysaccharides, Medicine, Saccharomyces cerevisiae, Animals, Glucans, Digestive System, Insect Biochemistry and Molecular Biology, Molecular weight, Periplaneta Americana, Cellulases, Cell Wall, Feeding Habit, Lytic Cycle, Glycosyl Hydrolases, and Biochemistry and cell biology
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Phlebotomine sand flies are of global significance as important vectors of human disease, transmitting bacterial, viral, and protozoan pathogens, including the devastating kinetoplastid parasites of the genus Leishmania, the causative... more
Phlebotomine sand flies are of global significance as important vectors of human disease, transmitting bacterial, viral, and protozoan pathogens, including the devastating kinetoplastid parasites of the genus Leishmania, the causative agents of diseases collectively termed leishmaniasis. More than 40 pathogenic Leishmania species are transmitted to humans by approximately 35 sand fly species in 98 countries with hundreds of millions of people at risk around the world. As no approved efficacious vaccine exists, available drugs are expensive and/or toxic, and resistance is emerging, management of sand fly populations to break transmission is currently the most effective disease control strategy. To better understand the biology of sand flies, including the mechanisms involved in their vectorial capacity, insecticide resistance, and population structures we sequenced the genomes of two of the most important sand fly species: Phlebotomus papatasi, a cutaneous leishmaniasis vector, (dist...
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BACKGROUNDLeishmaniasis is an infectious parasitic disease caused by pathogens of the genus Leishmania transmitted through the bite of adult female sand flies. To reduce case numbers, it is necessary to combine different control... more
BACKGROUNDLeishmaniasis is an infectious parasitic disease caused by pathogens of the genus Leishmania transmitted through the bite of adult female sand flies. To reduce case numbers, it is necessary to combine different control approaches, especially those aimed at the sand fly vectors. Innovative forms of control with the use of attractive sugar baits explored the fact that adult sand flies need to feed on sugars of plant origin. Leishmania parasites develop in the gut of sand flies, interacting with the sugars in the diet of adults. Recent studies have shown that sugar baits containing plant‐derived compounds can reduce sand fly survival, the number of parasites per gut, and the percentage of infected sand flies. Several synthetic compounds produced from naphthoquinones and pterocarpans have anti‐parasitic activity on Leishmania amazonensis and/or Leishmania infantum in cell culture. This work aimed to assess the inclusion of these compounds in sugar baits for blocking transmissi...
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There is increasing evidence supporting the immune memory in invertebrates, but the studies are relatively neglected in insect vectors other than mosquitoes. Therefore, we tested two hypotheses: 1) Rhodnius prolixus insects possess immune... more
There is increasing evidence supporting the immune memory in invertebrates, but the studies are relatively neglected in insect vectors other than mosquitoes. Therefore, we tested two hypotheses: 1) Rhodnius prolixus insects possess immune memory against Trypanosoma cruzi, and 2) their immune memory is costly. The Dm28c and Y strains of T. cruzi were used, the former being more infective than the latter. On the one hand, the triatomines subjected to dual challenges with the Dm28c strain did not show significant differences in survival than those of the heterologous challenge groups control-Dm28c and Y-Dm28c. On the other hand, the insects survived longer after a dual Y-Y challenge than after the corresponding heterologous challenge (control-Y). The Y-Y, Dm28c-Y, and naïve groups showed similar survival. There was more prolonged survival following the Y-Y versus Dm28c-Dm28c dual challenge. The Dm28c-Dm28c group exhibited moulting sooner than the control-Dm28c or naïve group. In contrast, there were no differences in the probability of moulting between the Y-Y and naïve groups. The results suggest that triatomines have immune memory against the Y but not the Dm28c strain. Further investigation on triatomine and T. cruzi interaction is needed to determine if infectivity accelerates or delay growth due to innate immune memory.
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<p>Bootstrap values above 50% are shown on the branches. The bottom line indicates 10% amino acid sequence divergence between the proteins. <i>R. prolixus</i> sequences are shown by the notation RP followed by a unique... more
<p>Bootstrap values above 50% are shown on the branches. The bottom line indicates 10% amino acid sequence divergence between the proteins. <i>R. prolixus</i> sequences are shown by the notation RP followed by a unique number and have a red circle preceding their names. The remaining sequences, obtained from GenBank, are annotated with the first three letters of the genus name, followed by the first three letters of the species name, followed by their GenBank GI number. One thousand replicates were done for the bootstrap test using the neighbor joining test.</p
Research Interests: Zoology, Entomology, Genomics, Computational Biology, Biology, and 12 moreInfectious Diseases, Medicine, Sequence Analysis, Functional Genomics, Biological Sciences, Anatomy and Physiology, Neglected tropical diseases, Chagas disease, Digestive System, Digestive physiology, Triatoma, and Rhodnius prolixus
Beta-1,3-glucanases are enzymes that hydrolyze beta-1,3-glucans, and they are essential for the metabolism of seaweed, plants and fungi. These enzymes also participate in the digestion of herbivore and fungivore animals. Because of the... more
Beta-1,3-glucanases are enzymes that hydrolyze beta-1,3-glucans, and they are essential for the metabolism of seaweed, plants and fungi. These enzymes also participate in the digestion of herbivore and fungivore animals. Because of the importance of these enzymes in insects, beta-1,3-glucanase inhibitors may be used for the development of new control strategies against agricultural pests and disease vectors. Beta-1,3-glucanase inhibitors have been described in the brown seaweed Laminaria cichorioides, but were never recorded in Brazilian seaweed species. We evaluated the presence of beta-1,3-glucanase inhibitors in samples of Padina gymnospora, Dictyota sp., Colpomenia sinuosa, and Lobophora sp., collected in Arraial d'Ajuda (Bahia). Ethanolic or buffer extracts were used in inhibition tests against the beta-1,3-glucanase of Trichoderma sp. Extracts in buffer showed no inhibition, but ethanolic extracts from all species showed different extents of inhibition. Samples from Dictyo...
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<p>Amino acid sequences of 46 contigs were combined to create an entry file for phylogenetic analysis in MEGA 4.0.2. An unrooted consensus neighbor joining tree was generated based on ten thousand bootstrap replicates with pairwise... more
<p>Amino acid sequences of 46 contigs were combined to create an entry file for phylogenetic analysis in MEGA 4.0.2. An unrooted consensus neighbor joining tree was generated based on ten thousand bootstrap replicates with pairwise gap deletions using neighbor joining method. Bootstrap values lower than 50% are not shown. Red boxes indicate the over expressed proteins. JHBP: Juvenile hormone binding proteins. OBP: Odorant binding proteins. CSP: Chemosensorial proteins. For more details, see text.</p