RESUMO
The aim of this study was to identify the composition of the essential oil from leaves of Lippia sidoides (EOLS), a typical shrub commonly found in the dry northeast of Brazil, popularly known as “alecrim-pimenta”. Additionally, we investigated the nymphicidal, ovicidal, phagoinhibitory and excretion effects of EOLS, its major constituent thymol and its isomer carvacrol, on fourth instar nymphs and eggs of Rhodnius prolixus, the Chagas’ disease vector. The nymphicidal and ovicidal activity of thymol, carvacrol, and EOLS was assessed by tests using impregnated Petri dishes. The lethal concentration values (LC50) for EOLS, carvacrol, and thymol were 54.48, 32.98, and 9.38 mg/cm2, respectively. The ovicidal test showed that both carvacrol and thymol (50 mg/cm2) inhibited hatching (50% and 23.3%, respectively), while treatments with 10 mg/cm2 or 50 mg/cm2 EOLS did not affect the hatching rate at all (80% and 90%, respectively). We observed an anti-feeding effect in insects fed with blood containing natural products at the higher concentrations (100 µg/mL). Finally, excretion rate was affected by EOLS and carvacrol, but not by thymol. These findings offer novel insights into basic physiological processes that make the tested natural compounds interesting candidates for new types of insecticides.
Assuntos
Animais , Rhodnius/parasitologia , Citotoxinas/química , Lippia , Disponibilidade BiológicaRESUMO
The aim of this study was to identify the composition of the essential oil from leaves of Lippia sidoides (EOLS), a typical shrub commonly found in the dry northeast of Brazil, popularly known as "alecrim-pimenta". Additionally, we investigated the nymphicidal, ovicidal, phagoinhibitory and excretion effects of EOLS, its major constituent thymol and its isomer carvacrol, on fourth instar nymphs and eggs of Rhodnius prolixus, the Chagas' disease vector. The nymphicidal and ovicidal activity of thymol, carvacrol, and EOLS was assessed by tests using impregnated Petri dishes. The lethal concentration values (LC50) for EOLS, carvacrol, and thymol were 54.48, 32.98, and 9.38 mg/cm2, respectively. The ovicidal test showed that both carvacrol and thymol (50 mg/cm2) inhibited hatching (50% and 23.3%, respectively), while treatments with 10 mg/cm2 or 50 mg/cm2 EOLS did not affect the hatching rate at all (80% and 90%, respectively). We observed an anti-feeding effect in insects fed with blood containing natural products at the higher concentrations (100 µg/mL). Finally, excretion rate was affected by EOLS and carvacrol, but not by thymol. These findings offer novel insights into basic physiological processes that make the tested natural compounds interesting candidates for new types of insecticides.
Assuntos
Lippia/química , Monoterpenos/administração & dosagem , Óleos Voláteis/administração & dosagem , Rhodnius/efeitos dos fármacos , Timol/administração & dosagem , Animais , Doença de Chagas/transmissão , Cimenos , Relação Dose-Resposta a Droga , Dose Letal MedianaRESUMO
The bloodsucking hemipteran Rhodnius prolixus is a vector of Chagas' disease, which affects 7-8 million people today in Latin America. In contrast to other hematophagous insects, the triatomine gut is compartmentalized into three segments that perform different functions during blood digestion. Here we report analysis of transcriptomes for each of the segments using pyrosequencing technology. Comparison of transcript frequency in digestive libraries with a whole-body library was used to evaluate expression levels. All classes of digestive enzymes were highly expressed, with a predominance of cysteine and aspartic proteinases, the latter showing a significant expansion through gene duplication. Although no protein digestion is known to occur in the anterior midgut (AM), protease transcripts were found, suggesting secretion as pro-enzymes, being possibly activated in the posterior midgut (PM). As expected, genes related to cytoskeleton, protein synthesis apparatus, protein traffic, and secretion were abundantly transcribed. Despite the absence of a chitinous peritrophic membrane in hemipterans - which have instead a lipidic perimicrovillar membrane lining over midgut epithelia - several gut-specific peritrophin transcripts were found, suggesting that these proteins perform functions other than being a structural component of the peritrophic membrane. Among immunity-related transcripts, while lysozymes and lectins were the most highly expressed, several genes belonging to the Toll pathway - found at low levels in the gut of most insects - were identified, contrasting with a low abundance of transcripts from IMD and STAT pathways. Analysis of transcripts related to lipid metabolism indicates that lipids play multiple roles, being a major energy source, a substrate for perimicrovillar membrane formation, and a source for hydrocarbons possibly to produce the wax layer of the hindgut. Transcripts related to amino acid metabolism showed an unanticipated priority for degradation of tyrosine, phenylalanine, and tryptophan. Analysis of transcripts related to signaling pathways suggested a role for MAP kinases, GTPases, and LKBP1/AMP kinases related to control of cell shape and polarity, possibly in connection with regulation of cell survival, response of pathogens and nutrients. Together, our findings present a new view of the triatomine digestive apparatus and will help us understand trypanosome interaction and allow insights into hemipteran metabolic adaptations to a blood-based diet.
Assuntos
Proteínas de Insetos/genética , Rhodnius/genética , Transcriptoma , Animais , Feminino , Trato Gastrointestinal , Proteínas de Insetos/biossíntese , América Latina , Masculino , Dados de Sequência Molecular , Análise de Sequência de DNARESUMO
In the present study, we investigated the involvement of sulfated glycosaminoglycans in both the in vivo development and adhesion of T. cruzi epimastigotes to the luminal surface of the digestive tract of the insect vector, Rhodnius prolixus. Pre-incubation of T. cruzi, Dm 28c epimastigotes with heparin, chondroitin 4-sulfate, chondroitin 6-sulfate or protamine chloridrate inhibited in vitro attachment of parasites to the insect midgut. Enzymatic removal of heparan sulfate moieties by heparinase I or of chondroitin sulfate moieties by chondroitinase AC from the insect posterior midgut abolished epimastigote attachment in vitro. These treatments also reduced the labelling of anionic sites exposed at the luminal surface of the perimicrovillar membranes in the triatomine midgut epithelial cells. Inclusion of chondroitin 4-sulfate or chondroitin 6-sulfate and to a lesser extent, heparin, in the T. cruzi-infected bloodmeal inhibited the establishment of parasites in R. prolixus. These observations indicate that sulfated glycosaminoglycans are one of the determinants for both adhesion of the T. cruzi epimastigotes to the posterior midgut epithelial cells of the triatomine and the parasite infection in the insect vector, R. prolixus.
Assuntos
Doença de Chagas/parasitologia , Trato Gastrointestinal/parasitologia , Glicosaminoglicanos/farmacologia , Insetos Vetores/parasitologia , Rhodnius/parasitologia , Trypanosoma cruzi/efeitos dos fármacos , Animais , Adesão Celular/efeitos dos fármacos , Células Epiteliais/parasitologia , Insetos Vetores/citologia , Larva , Masculino , Rhodnius/citologia , Trypanosoma cruzi/crescimento & desenvolvimentoRESUMO
In this overview, some of the more significant recent developments in bioengineering natural products from insects with use or potential use in modern medicine are described, as well as in utilisation of insects as models for studying essential mammalian processes such as immune responses to pathogens. To date, insects have been relatively neglected as sources of modern drugs although they have provided valuable natural products, including honey and silk, for at least 4-7000 years, and have featured in folklore medicine for thousands of years. Particular examples of Insect Folk Medicines will briefly be described which have subsequently led through the application of molecular and bioengineering techniques to the development of bioactive compounds with great potential as pharmaceuticals in modern medicine. Insect products reviewed have been derived from honey, venom, silk, cantharidin, whole insect extracts, maggots, and blood-sucking arthropods. Drug activities detected include powerful antimicrobials against antibiotic-resistant bacteria and HIV, as well as anti-cancer, anti-angiogenesis and anti-coagulant factors and wound healing agents. Finally, the many problems in developing these insect products as human therapeutic drugs are considered and the possible solutions emerging to these problems are described.
Assuntos
Produtos Biológicos/uso terapêutico , Insetos/química , Animais , Antibacterianos/análise , Antineoplásicos/análise , Venenos de Artrópodes/uso terapêutico , Cantaridina/uso terapêutico , Desbridamento , Descoberta de Drogas , Comportamento Alimentar , Mel , Humanos , Larva , Medicina Tradicional , Seda/uso terapêutico , CicatrizaçãoRESUMO
Bacteria, fungi and parasites are in constant contact with the insect gut environment and can influence different aspects of the host gut physiology. Usually, some of these microorganisms develop and survive in the digestive tract. Therefore, the gut environment must be able to tolerate certain populations of these organisms for the establishment of interactions between non-pathogenic bacteria, parasites and the gut. This review provides a brief overview of the biological and molecular mechanisms that microorganisms use to interact with the gut epithelia in mosquitoes and speculates on their significances for the development of bacteria and Trypanosoma cruzi in the guts of triatomines.
Assuntos
Animais , Culicidae , Homeostase/imunologia , Interações Hospedeiro-Parasita/imunologia , Culicidae/imunologia , Culicidae , Culicidae , Sistema Digestório/imunologia , Sistema Digestório , Sistema Digestório , Triatominae/imunologia , Triatominae , Triatominae , Trypanosoma cruzi/crescimento & desenvolvimentoRESUMO
Perimicrovillar membranes (PMM) are structures present on the surface of midgut epithelial cells of the hematophagous insect, Rhodnius prolixus. They cover the microvilli and are especially evident 10 days after blood meal, providing the compartmentalization of the enzymatic processes in the intestinal microenvironment. Using an enzyme cytochemical approach, Mg2+-ATPase and ouabain-sensitive Na+K+-ATPase activities were observed in the plasma (or microvillar) membrane (MM) of midgut cells and in the PMM. In contrast, alkaline phosphatase was only detected in MM. Using cationized ferritin and colloidal iron hydroxide particles, anionic sites were found only on the luminal surface of the PMM. Using fluorescein isothiocyanate (FITC)-labeled lectins, residues of alpha-d-galactose, mannose, N-acetyl-neuraminic acid, N-acetyl-d-galactosamine and N-acetyl-galactosamine-alpha-1,3-galactose were detected on the apical surface of posterior midgut epithelial cells. On the other hand, using FITC-labeled neoglycoproteins (NGP) it was possible to detect the presence of carbohydrate binding molecules (CBM) recognizing N-acetyl-d-galactosamine, alpha-d-mannose, alpha-l-fucose and alpha-d-glucose in the posterior midgut epithelium. The use of digitonin showed the presence of sterols in the MM and PMM. These results have led the authors to suggest that for some components the PMM resembles the MM lining the midgut cells of R. prolixus, composing a system which covers the microvilli and stretches to the luminal space.
Assuntos
Mucosa Intestinal/citologia , Microvilosidades/ultraestrutura , Rhodnius/citologia , Animais , ATPase de Ca(2+) e Mg(2+)/metabolismo , Fluoresceína-5-Isotiocianato , Histocitoquímica , ATPase Trocadora de Sódio-Potássio/metabolismo , Esteróis/metabolismoRESUMO
The effects of the triazolodiazepine WEB 2086, a platelet-activating factor (PAF) antagonist, on hemocyte microaggregation and prophenoloxidase (proPO)-activating system in the hemolymph, hemocoelic infection and mortality in fifth-instar larvae of Rhodnius prolixus inoculated with Trypanosoma rangeli were investigated. Hemocoelic injection of short T. rangeli epimastigotes (1x10(4) parasites/insect) in R. prolixus that were previously fed with blood containing 1muM of WEB 2086 resulted in (i) reduced hemocyte microaggregations as well as an attenuated proPO system in the hemolymph and (ii) greater parasitemia and mortality among the insects. In vitro assays using hemolymph from insects previously fed with blood containing WEB 2086 exhibited attenuated hemocyte microaggregations when T. rangeli was employed as the inducer of the reaction, and this effect was not counteracted by PAF treatment. In vitro assays using hemolymph from insects previously fed with blood, regardless of WEB 2086 presence increased the PO activity when incubated with the parasites. However, the PO activity was drastically inhibited when hemolymph from insects fed with blood, whether or not it contained WEB 2086, was incubated with fat body homogenates from insects fed with blood containing WEB 2086. The addition of PAF did not enhance the PO activity. These analyses did not reveal any PAF influence on WEB 2086 effects in the two defense reactions.
Assuntos
Azepinas/farmacologia , Catecol Oxidase/fisiologia , Precursores Enzimáticos/fisiologia , Hemócitos/fisiologia , Fator de Ativação de Plaquetas/fisiologia , Inibidores da Agregação Plaquetária/farmacologia , Rhodnius/imunologia , Triazóis/farmacologia , Trypanosoma/fisiologia , Animais , Catecol Oxidase/metabolismo , Precursores Enzimáticos/metabolismo , Hemolinfa/imunologia , Larva/imunologia , Larva/parasitologia , Fator de Ativação de Plaquetas/antagonistas & inibidores , Rhodnius/parasitologiaRESUMO
Physalins are seco-steroids obtained from plants of the family Solanaceae. Herein, we tested Physalis angulata L purified physalin B as an immunomodulatory compound in 5th-instar larvae of Rhodnius prolixus, which were systemically infected with the H14 Trypanosoma rangeli strain protozoan. In uninfected insects, the effective concentration of physalin B, which inhibited 50% of the blood ingested (ED(50)) volume, was 15.2+/-1.6 microg/ml of the meal. Ecdysis processes and mortality in uninfected larvae, treated orally with physalin B in concentrations ranging from 1 to 10 microg/ml, was similar to that observed in insects not treated with physalin B. However, R. prolixus larvae previously fed on blood containing 1.0, 0.1, and 0.01 microg of physalin B/ml exhibited mortality rates of 78.1, 54.3, and 12.7%, respectively, 6 days after inoculation of T. rangeli (1 x 10(3) parasites/insect), whereas only 7.2% mortality was observed in the control group, injected with sterile culture medium. The insects treated with physalin B (0.1 microg/ml) and inoculated with T. rangeli did not modify the phenoloxidase (PO) activity and total hemocyte count in the hemolymph. However, physalin B treatment caused a reduction in hemocyte micro-aggregation and nitric oxide production and enhanced the parasitemia in the hemolymph. These results demonstrate that physalin B from P. angulata is a potent immunomodulatory substance for the bloodsucking insect, R. prolixus.
Assuntos
Lactonas/farmacologia , Rhodnius/imunologia , Esteroides/farmacologia , Trypanosoma/imunologia , Animais , Catecol Oxidase/metabolismo , Agregação Celular/efeitos dos fármacos , Contagem de Células , Ativação Enzimática/efeitos dos fármacos , Precursores Enzimáticos/metabolismo , Hemócitos/citologia , Hemócitos/efeitos dos fármacos , Lactonas/química , Larva/efeitos dos fármacos , Larva/imunologia , Larva/parasitologia , Nitratos/metabolismo , Nitritos/metabolismo , Rhodnius/efeitos dos fármacos , Rhodnius/parasitologia , Secoesteroides , Esteroides/químicaRESUMO
O livro traz uma análise sobre a fronteira entre ciência e tecnologia, focalizando as novas idéias da era pós-genômica. Com uma linguagem clara e compreensível, o autor analisa os avanços científicos e suas conseqüências para a humanidade, com foco no desenvolvimento da biologia molecular e da genética.
Assuntos
Clonagem de Organismos , Genes , Genômica , Projeto Genoma Humano , ProteômicaRESUMO
Esta revisão destaca aspectos dos estágios do desenvolvimento de Trypanosoma cruzi e Trypanosoma rangeli em seu hospedeiro invertebrado, Rhodnius prolixus Atenção especial é dada às interações desses parasitas com moléculas presentes no tubo digestivo e na hemolinfa e efeitos da organização das células epiteliais sobre o desenvolvimento do parasita. A susceptibilidade do inseto vetor ao T. cruzi, o qual desenvolve no tubo digestivo, dependem do estado nutricional do hospedeiro, da cepa do parasita e de interações moleculares com compostos tripanolíticos, lectinas e bactérias residentes no tubo digestivo. O T. rangeli invade a hemocele e pode ser reconhecido e ativar o sistema de defesa do inseto vetor, ou seja, o sistema profenoloxidase, fagocitose, microagregação hemocitária,atividade de superóxido e óxido nítrico e a via de biossíntese dos eicosanóides. Estes fatos fornecem uma compreensão melhor das interações parasita-inseto vetor, e também oferecem novas idéias sobre os processos básicos envolvidos na transmissão parasitária.
Assuntos
Animais , Insetos Vetores/parasitologia , Rhodnius/parasitologia , Trypanosoma/fisiologia , Hemolinfa/parasitologia , Interações Hospedeiro-Parasita/fisiologia , Trypanosoma cruzi/fisiologia , Trypanosoma/crescimento & desenvolvimentoRESUMO
This article is an integrative mini review of the research on the interactions between Trypanosoma rangeli and the insect vector, Rhodnius prolixus. Special attention is given to the interactions of these parasites with the gut environment, gut walls, with hemolymph invasion, hemocytes, hemocyte microaggregations, prophenoloxidase-activating system, superoxide, and nitric acid generation and eicosanoid pathways. We described factors affecting vectorial capacity and suggested that T. rangeli may modulate the hemocoelic invasion and the survival of the parasites by overcoming the cellular and humoral defense reactions of the insect vector at different physiological events. The mechanisms of these interactions and their significance for parasite transmission are discussed.
Assuntos
Animais , Insetos Vetores/parasitologia , Rhodnius/parasitologia , Trypanosoma/fisiologia , Interações Hospedeiro-Parasita/fisiologiaRESUMO
Analysis of zymograms with SDS-polyacrilamide gel electrophoresis containing gelatin as substrate, and performed on samples of haemolymph or fat body taken from Rhodnius prolixus inoculated or not with Enterobacter cloacae, demonstrated distinct patterns of protease activities: (i) in the haemolymph two proteases were induced in insects inoculated with bacteria; (ii) two proteases were detected in the fat bodies derived from non-inoculated controls or insect inoculated with sterile culture medium; (iii) haemolymph and fat body had both the same apparent molecular weights proteases (46 and 56 kDa); and (iv) these enzymes were characterized as metallo-proteases. The association of these enzymes in Rhodnius infected with bacteria was discussed.
Assuntos
Animais , Enterobacter cloacae/enzimologia , Corpo Adiposo/parasitologia , Hemolinfa/parasitologia , Metaloproteases , Rhodnius/enzimologiaRESUMO
Applied topically to larvae of Rhodnius prolixus Stal, Triatoma infestans (Klug) and Panstrongylus herreri Wygodzinsky, vectors of Trypanosoma cruzi, the causative agent of Chagas' disease, a synthetic, furan-containing anti-juveline hormonal compound, 2-(2-ethoxyethoxy) ethyl furfuryl ether induced a variety of biomorphological alterations, including precocious metamorphosis into small adultoids with adult abdominal cuticle, ocelli, as well as rudimentary adultoid wings. Some adultoids died during ecdysis and were confined within the old cuticle. The extension of these biomorphological responses is discussed in terms of the complexity of the action of anti-juvenile hormonal compounds during the development of triatomines.
Assuntos
Animais , Larva/efeitos dos fármacos , Panstrongylus/anatomia & histologia , Rhodnius/anatomia & histologia , Triatoma/anatomia & histologia , Triatominae/anatomia & histologia , Éter/síntese química , Hormônios Juvenis/síntese químicaRESUMO
Traz a discussäo sobre genética molecular em saúde ao campo da saúde pública. Com a revoluçäo produzida pela chegada da engenharia genética, é importante discutir alguns dos avanços e problemas desta tecnologia para a sociedade. Está na hora de se fazer uma avaliaçäo clara e bem informada acerca do que já se conseguiu e do que ainda podemos conseguir através desta tecnologia. A sociedade precisa compreender as implicaçöes éticas e práticas de uma tecnologia capaz de produzir drogas milagrosas, diagnósticos modernos e a cura de todas as doenças. Alguns pontos particularmente delicados pertinentes às questöes sociais ligadas à biologia molecular e ao projeto genoma humano säo discutidos.
Assuntos
Biologia Molecular , Biotecnologia , Ética , Genoma HumanoRESUMO
A study of the phagoinhibitor and anti-moulting activities of the Brazilian Melia azedarach, collected in the state of Rio de Janeiro, Brazil, allowed the isolation of four lignanes identified as pinoresinol, bis-epi-pinoresinol, the hemicetal and the diacid. These substances are devoid of anti-moulting activity.
Assuntos
Animais , Lignina/isolamento & purificação , Plantas/química , RhodniusRESUMO
Apresenta a importância da biodiversidade, da biotecnologia e da saúde e discute vários aspectos dos problemas biológicos, ambientais e o dilema ético, relacionados com a expansäo e a exploraçäo dos recursos naturais em razäo das quais espécies de plantas e animais têm sido extintas. Por outro lado, o conhecimento da biodiversidade tem possibilitado a identificaçäo e a utilizaçäo de novos recursos naturais para a melhoria da vida do homem neste planeta. É importante que nossos pesquisadores se envolvam na luta pela preservaçäo do ecossistema tropical. Os programas de exploraçäo da biodiversidade devem estar baseados em sólidos conhecimentos científicos e favorecer ecológica e economicamente a sociedade.