RESUMO
Triatomine bugs carry the parasitic protozoa Trypanosoma cruzi, the causal agent of Chagas disease. It is known that both the parasite and entomopathogenic fungi can decrease bug survival, but the combined effect of both pathogens is not known, which is relevant for biological control purposes. Herein, the survival of the triatomine Meccus pallidipennis (Stal, 1872) was compared when it was coinfected with the fungus Metarhizium anisopliae (Metschnikoff) and T. cruzi, and when both pathogens acted separately. The immune response of the insect was also studied, using phenoloxidase activity in the bug gut and hemolymph, to understand our survival results. Contrary to expectations, triatomine survival was higher in multiple than in single challenges, even though the immune response was lower in cases of multiple infection. We postulate that T. cruzi exerts a protective effect and/or that the insect reduced the resources allocated to defend itself against both pathogens. Based on the present results, the use of M. anisopliae as a control agent should be re-considered.
Assuntos
Coinfecção , Metarhizium/patogenicidade , Triatominae/microbiologia , Triatominae/parasitologia , Trypanosoma cruzi/patogenicidade , Animais , Agentes de Controle Biológico , Doença de Chagas/prevenção & controle , Insetos Vetores/microbiologia , Insetos Vetores/parasitologia , Camundongos , Monofenol Mono-Oxigenase/metabolismo , Ninfa/imunologia , Ninfa/microbiologia , Ninfa/parasitologia , Triatominae/enzimologia , Triatominae/imunologiaRESUMO
Triatomine bugs are vectors of Trypanosoma cruzi, the etiologic agent of Chagas disease, a devastating disease that disables and leads to the death of many people in Latin America. In this review, factors from the insect vector are described, including digestive enzymes, hemolysins, agglutinins, microbiota and especially antimicrobial factors, which are potentially involved in regulating the development of T. cruzi in the gut. Differential regulation of parasite populations shows that some triatomine defense reactions discriminate not only between molecular signals specific for trypanosome infections but also between different strains of T. cruzi.
Assuntos
Interações Hospedeiro-Parasita/fisiologia , Triatominae/fisiologia , Triatominae/parasitologia , Trypanosoma cruzi/fisiologia , Trypanosoma cruzi/patogenicidade , Animais , Doença de Chagas/parasitologia , Doença de Chagas/transmissão , Vetores de Doenças , Humanos , Estágios do Ciclo de Vida , Triatominae/enzimologiaRESUMO
Acid phosphatase activity (Gömori technique) in salivary gland cells was investigated in adult insects (males and females) of four species of triatomines: Triatoma infestans, Panstrongylus megistus, Rhodnius neglectus, and Rhodnius prolixus. Binucleated cells with bulky and polyploidy nuclei were detected, with acid phosphatase activity in the heterochromatin and nucleolus, which showed the most intense response. Thus, the activity of these phosphatases during rRNA molecule transcription, possibly in the nucleolar fibrillar center, is suggested. The difference in reactivity found among salivary glands is associated with the cellular metabolism of these regions and, probably, with the biosynthesis of their different secretions. This must be essential in maintaining the hematophagy of triatomines.
Assuntos
Fosfatase Ácida/metabolismo , Núcleo Celular/enzimologia , Glândulas Salivares/enzimologia , Triatominae/enzimologia , Animais , Feminino , Masculino , Glândulas Salivares/citologiaRESUMO
Acid phosphatase activity (Gömori technique) in salivary gland cells was investigated in adult insects (males and females) of four species of triatomines: Triatoma infestans, Panstrongylus megistus, Rhodnius neglectus, and Rhodnius prolixus. Binucleated cells with bulky and polyploidy nuclei were detected, with acid phosphatase activity in the heterochromatin and nucleolus, which showed the most intense response. Thus, the activity of these phosphatases during rRNA molecule transcription, possibly in the nucleolar fibrillar center, is suggested. The difference in reactivity found among salivary glands is associated with the cellular metabolism of these regions and, probably, with the biosynthesis of their different secretions. This must be essential in maintaining the hematophagy of triatomines
Assuntos
Animais , Masculino , Feminino , Fosfatase Ácida/metabolismo , Núcleo Celular/enzimologia , Glândulas Salivares/enzimologia , Triatominae/enzimologia , Glândulas Salivares/citologiaRESUMO
Genetic relationships among 10 species of bugs belonging to the tribe Rhodniini (Hemiptera: Reduviidae), including some important vectors of Chagas disease, were inferred from allozyme analysis of 12 enzyme loci (out of 21 enzyme systems examined), using agarose gel electrophoresis. These species formed two clusters: one comprising Rhodnius brethesi, R. ecuadoriensis, R. pallescens and R. pictipes; the other with Psammolestes tertius, Rhodnius domesticus and the Rhodnius prolixus group comprising R. nasutus, R. neglectus, R. prolixus and R. robustus. The resulting tree was [((R. ecuadoriensis, R. pallescens) R. brethesi) R. pictipes], [R. domesticus (P. tertius [(R. nasutus, R. neglectus) (R. prolixus, R. robustus)])]. Rhodnius nasutus and R. neglectus differed by only one locus, whereas no diagnostic loci were detected between R. prolixus and R. robustus (22 loci were analysed for these four species), despite considerable DNA sequence divergence between species in each of these pairs. Allozymes of the R. prolixus group showed greater similarity with Psammolestes tertius than with other Rhodnius spp., indicating that Rhodnius is paraphyletic and might include Psammolestes.
Assuntos
Doença de Chagas/transmissão , Isoenzimas/genética , Rhodnius/classificação , Rhodnius/enzimologia , Triatominae/classificação , Triatominae/enzimologia , Animais , Eletroforese em Gel de Ágar/veterinária , Insetos Vetores/classificação , Insetos Vetores/enzimologia , Insetos Vetores/genética , Isoenzimas/análise , Filogenia , Rhodnius/genética , Especificidade da Espécie , Triatominae/genéticaRESUMO
The oliveirai complex is actually composed of nine related species of Triatominae that occur in the Pantanal ecosystem of Mato Grosso, Brazil. In order to confirm their specific status and infer their phylogenetic relationships, we performed a genetic and morphometric comparison concerning seven of the nine species of the complex. Isoenzyme analysis provided broadly similar phylogenetic information to that derived from discriminant analysis of size-free variables. The derived trees reveal two main species groups, one composed of three closed species (T. jurbergi, T. matogrossensis and T. vandae), and another one subdivided into two different pairs, the T. guazu-T. williami pair and the T. klugi-T. oliveirai pair. The results call the specific status of T. guazu and T. williami into question, support the possibility that the other analyzed species represent distinct taxa and query the existence of the oliveirai complex.
Assuntos
Filogenia , Triatominae/genética , Animais , Brasil , Isoenzimas/genética , Análise de Sequência de DNA , Triatominae/classificação , Triatominae/enzimologiaRESUMO
Two Brazilian populations of Psammolestes tertius (Ceará and Minas Gerais) collected from thornbird nests (Furnariidae) were compared by male genital morphology, morphometry, isoenzymes, and random amplified polymorphic DNA (RAPD). Male genitalia showed no difference between the populations. In contrast, morphometry, isoenzyme, and RAPD clearly distinguished the two populations. Possible mechanisms of dispersal and the origin of Psammolestes are discussed.
Assuntos
Genitália Masculina/anatomia & histologia , Oxirredutases/metabolismo , Triatominae/genética , Animais , Pesos e Medidas Corporais/métodos , DNA de Protozoário/análise , Feminino , Variação Genética , Himenópteros , Isoenzimas/metabolismo , Masculino , Técnica de Amplificação ao Acaso de DNA Polimórfico , Rhodnius , Triatominae/enzimologia , VespasRESUMO
Activities of hexokinase (HK), glucose-6-phosphate dehydrogenase (G6PDH), fructose-6-phosphate kinase (F6PK), glutamate dehydrogenase (GlutDH), aspartate aminotransferase (AAT), malate dehydrogenase (MDH) and glycerol-3-phosphate dehydrogenase (GPDH) were determined in tissue extracts of testes and ovaries of adult Dipetalogaster maximus (Uhler) and Triatoma infestans (Klug) (Hemiptera: Reduviidae), insect vectors of Chagas disease. The fine structure organization of the same organs were studied by electron microscopy. Results allow the following inferences: in testes from both species, most of the glucose would be utilized through the glycolytic pathway. Amino acid catabolism for energy purposes appears to be unimportant. The number of mitochondria and the development of the rough endoplasmic reticulum in cells of the spermatogenic line indicate the occurrence of active oxidative metabolism and protein synthesis; in ovaries, levels of G6PDH indicate the existence of an active pentose pathway which would supply the NADPH required for fat and ecdysteroid synthesis. Amino acid catabolism appears to be relatively more important in ovary than in testis. Fat and glycogen are stored in follicular cells of D. maximus; oocytes of both species contain numerous fat droplets. Abundant mitocondria are present in follicular cells and oocytes. A well developed rough endoplasmic reticulum and free ribosomes are also conspicuous in these cells. The malate/aspartate H-transfer system seemed to be relatively more important than the glycerophosphate shuttle in ovaries as well in testes.
Assuntos
Insetos Vetores/enzimologia , Ovário/enzimologia , Oxirredutases/metabolismo , Testículo/enzimologia , Triatominae/enzimologia , Animais , Feminino , Insetos Vetores/ultraestrutura , Masculino , Microscopia Eletrônica , Ovário/ultraestrutura , Especificidade da Espécie , Testículo/ultraestrutura , Triatominae/ultraestruturaRESUMO
The alpha-glycerophosphate dehydrogenase (alpha-GPDH) activity in flight muscles of Panstrongylus megistus and Triatoma sordida, vectors of Chagas disease in Brazil, was studied. Both species showed higher enzymatic activities in fliers than in non-fliers insects. T. sordida exhibited a higher proportion of flier insects than P. megistus. A possible role of alpha-GPDH on triatomines flight is discussed.
Assuntos
Animais , Voo Animal/fisiologia , Glicerolfosfato Desidrogenase/metabolismo , Insetos Vetores/enzimologia , Músculos/enzimologia , Triatominae/enzimologia , Glicerolfosfato Desidrogenase/fisiologia , Panstrongylus/enzimologia , Triatoma/enzimologiaRESUMO
Effects of temperature and pH on the catalytic properties of hexokinase (HK, EC 2.7.1.1) from the flight muscles of Dipetalogaster maximus (Uhler) were studied. The enzyme showed a hyperbolic behavior with its two substrates (glucose and ATP). There was no inhibition by glucose. Apparent Km and Vmax increased as pH increased from 7.0 to 8.5. Catalytic efficiency was lowest at pH 7.0. Km, Vmax, and catalytic efficiency were higher at 37 degrees C than at 30 and 20 degrees C. There was marked inhibition by ATP, which was dependent on pH and temperature. Km values for ATP were reduced and catalytic efficiency increased as pH increased. Lowest Vmax was observed at pH 7.0. At this pH there was 87.3% inhibition by ATP, whereas it was only 5.7% at pH 8.5 (at 30 degrees C). Km, Vmax, and catalytic efficiency were higher at 37 degrees C than at 30 and 20 degrees C. The strong inhibition by ATP detected at 20 degrees C (pH 7.6) almost disappeared at 37 degrees C. Therefore, temperature could regulate hexokinase activity by modulating the inhibition produced by ATP. Glucose utilization and ATP production would be promoted when temperature rises from 30 to 37 degrees C. Because insect thoracic muscles increase their temperature over 30 degrees C during flight, this phenomenon elucidates a mechanism enhancing energy supply for muscle activity.