Abstract Resistance to benznidazole in certain strains of Trypanosoma cruzi may be caused by the increased production of enzymes that act on the oxidative metabolism, such as mitochondrial tryparedoxin peroxidase which catalyses the reduction of peroxides. This work presents cytotoxicity assays performed with ferrocenyl diamine hydrochlorides in six different strains of T. cruzi epimastigote forms (Y, Bolivia, SI1, SI8, QMII, and SIGR3). The last four strains have been recently isolated from triatominae and mammalian host (domestic cat). The expression of mitochondrial tryparedoxin peroxidase was analyzed by the Western blotting technique using polyclonal antibody anti mitochondrial tryparedoxin peroxidase obtained from a rabbit immunized with the mitochondrial tryparedoxin peroxidase recombinant protein. All the tested ferrocenyl diamine hydrochlorides were more cytotoxic than benznidazole. The expression of the 25.5 kDa polypeptide of mitochondrial tryparedoxin peroxidase did not increase in strains that were more resistant to the ferrocenyl compounds (SI8 and SIGR3). In addition, a 58 kDa polypeptide was also recognized in all strains. Ferrocenyl diamine hydrochlorides showed trypanocidal activity and the expression of 25.5 kDa mitochondrial tryparedoxin peroxidase is not necessarily increased in some T. cruzi strains. Most likely, other mechanisms, in addition to the over expression of this antioxidative enzyme, should be involved in the escape of parasites from cytotoxic oxidant agents.

The present study describes the antiprotozoal activities of four cyclopalladated compounds, [Pd(dmba)(μ-Cl)]2, [Pd(dmba)(NCO)(isn)], [Pd(dmba)(N3)(isn)] and [Pd(dmba)(μ-NCO)]2, (dmba: N,N'-dimethylbenzylamine and isn: isonicotinamide), against the diseases leishmaniasis (Leishmania amazonensis and Leishmania infantum), Chagas disease (Trypanosoma cruzi) and human African trypanosomiasis (Trypanosoma brucei). [Pd(dmba)(μ-NCO)]2 exhibited good leishmanicidal and trypanocidal activities against L. amazonensis and T. cruzi intracellular amastigote forms, with a 50% inhibitory concentration (IC50) value of less than 9 µM and selectivity indexes of 14.47 and 28.42, respectively. Stability essays were conducted in phosphate buffer saline (PBS) pH 7.0 and showed that [Pd(dmba)(μ-NCO)]2 is the most stable molecule. These findings indicate that this compound presented higher selectivity for these parasites than the other tested compounds. The data presented here suggest that this compound should be considered in the development of new and more potent drugs for the treatment of leishmaniasis and Chagas disease.

The length of the four right antennal segments from nymphs and adults of Panstrongylus megistus Burmeister, Rhodnius neglectus Lent, Rhodnius prolixus Stal and Triatoma vitticeps Stal were measured. The length of the antennal segments of the adults of all four species, 4th and 5th instars of P. megistus, and 5th instar of R. neglectus and R. prolixus followed the same pattern: 2nd>3rd>4th>1st. The pattern of 1st and 2nd instars of P. megistus was: 4th>3rd>2nd>1st. For 3rd instars of P. megistus, 1st and 2nd instars of R. neglectus and R. prolixus they were: 3rd>4th>2nd>1st. Third and 4th instars of Rhodnius neglectus and R. prolixus had a pattern of: 3rd>2nd>4th>1st. Only T. vitticeps showed the same pattern (4th>3rd>2nd>1st) for all five instars. The morphological study of the second antennal segment by scanning electron microscopy (SEM) disclosed that the first instars of all four species exhibit type I bristles sensillae and one trichobothrium. Another type III bristle and basiconic, campaniform, coeloconic, trichoid sensillae and type I bristle and trichobothria were noted on their fourth instars and adults. Campaniform sensillae were noted only on T. vitticeps adults. Nodules were observed in the joint between 1st and 2nd antennal segments of adults of P. megistus and T. vitticeps, but not on R. neglectus and R. prolixus.

The authors describe and compare the morphological and ultrastructural characteristics of eggs from the three most recent described species of the genus Rhodnius Stål, 1859, which have not previously been studied. These species are Rhodnius colombiensis (Mejia, Galvão & Jurberg 1999), Rhodnius milesi (Carcavallo, Rocha, Galvão & Jurberg 2001) and Rhodnius stali (Lent, Jurberg & Galvão 1993). The results revealed that there are similarities in the exochorial architecture of optical microscopy and scanning electron microscopy; these include the predominance of hexagonal cells that are common to all Rhodnius species and variable degrees of lateral flattening, which is common not only to species of this genus, but also to the Rhodniini tribe. Differences in overall colour, the presence of a collar in R. milesi, a longitudinal bevel in R. stali and the precise length of R. colombiensis can be useful distinguishing features. As a result of this study, the key for egg identification proposed by Barata in 1981 can be updated.

O objetivo deste trabalho foi analisar as características morfológicas e histológicas dos ovos de seis espécies de triatomíneos, buscando a caracterização específica e genérica desses grupo de vetores do Trypanosoma cruzi e a melhor compreensão seus aspectos filogenéticos e taxonômicos. Os ovos das espécies estudadas foram obtidos no acervo do Laboratório de Triatomíneos e Culicídeos da Faculdade de Saúde Pública/USP, do Insetário do Serviço Especial de Saúde de Araraquara - SESA e do insetário de triatomíneos do Laboratório Nacional e Internacional de Referência em Taxonomia de Triatomíneos da FIOCRUZ, RJ. Estudos morfológicos foram realizados por meio de microscopia óptica e microscopia eletrônica de varredura. Nos estudos histológicos, utilizou-se microscopia óptica. Todas as espécies analisadas apresentaram predominância de células hexagonais. O exocório de Triatoma breyeri Del Ponte, T. costalimai Verano & Galvão e T. tibiamaculata (Pinto) é constituído por células sem ornamentações, justapostas ou levemente separadas, de aspecto liso e acolchoado. Por outro lado, em T. matogrossensis Leite & Barbosa, T. sherlocki Papa, Juberg, Carcavallo, Cerqueira & Barata e T. williami Galvão, Souza & Lima, as células do exocório apresentam ornamentações, tais como, perfurações e fraturas distribuídas em toda a superfície. Na histologia dos ovos observou-se a presença de ondulações, poros e orifícios. O estudo contribui para a ampliação do reconhecimento genérico e específico da subfamília Triatominae. As características identificadas no exocório das cascas dos ovos podem auxiliar na correta determinação de espécies próximas. Esses novos parâmetros poderão subsidiar a elaboração de futuras chaves dicotômicas e auxiliar na determinação do papel de cada espécie vetora.

The objective of this study was to analyze the morphological and histological characteristics of eggs from six triatomine species in order to obtain a generic and specific characterization of this group of Trypanosoma cruzi vectors and better understand their phylogenetic and taxonomic aspects. The eggs of the respective species came from the collection of the Laboratório de Triatomíneos e Culicídeos da Faculdade de Saúde Pública/USP, from the Insetário do Serviço Especial de Saúde de Araraquara - SESA and from the Triatomine insectary of the Laboratório Nacional e Internacional de Referência em Taxonomia de Triatomíneos (FIOCRUZ), in Rio de Janeiro. Morphological studies were done with optical microscopy and scanning electron microscopy. Histological analyses used only optical microscopy. All of the species analyzed showed a predominance of hexagonal cells. The exchorion of Triatoma breyeri Del Ponte, T. costalimai Verano & Galvão, and T. tibiamaculata (Pinto) consists of unornamented cells, overlapping or slightly separated, with a smooth, padded appearance. Meanwhile, in T. matogrossensis Leite & Barbosa, T. sherlocki Papa, Juberg, Carcavallo, Cerqueira & Barata, and T. williami Galvão, Souza & Lima, the exchorion cells are ornamented on their entire surface with perforations and fissures. Egg histology showed undulations, pores, and orifices. The study helps to expand the generic and specific knowledge of the Triatominae subfamily. The characteristics identified in the exchorion of the eggshells can help separate close species. These new parameters will back the elaboration of future dichotomous keys, help to determine each vector species’ role and expand knowledge of the various species.

O objetivo do estudo foi avaliar as mensurações de cascas de ovos de duas colônias laboratoriais e uma silvestre de P. megistus. De cada uma das colônias, 50 cascas de ovos foram mensuradas por meio de microscópio estereoscópico e sistema de análise de imagem QWin. A análise estatística foi efetuada utilizando o teste t-Student, não pareado no programa INSTAT. A largura, o comprimento e o diâmetro da abertura opercular das cascas de ovos de uma colônia silvestre foram maiores que de duas colônias laboratoriais de P. megistus.

The objective of the study was to evaluate the measurements of eggshells from three colonies of P. megistus, two from the lab and one from a sylvatic habitat. Fifty eggshells from each colony were measured with the use of a stereoscopic microscope and the Qwin image analysis system,. The statistical analysis was performed using unpaired t-test in INSTAT program. The length, width and diameter of the opercular opening of the eggshells from the sylvatic colony were larger than the two laboratorial colonies of P. megistus.

O objetivo do estudo foi avaliar as mensurações de cascas de ovos de duas colônias laboratoriais e uma silvestre de P. megistus. De cada uma das colônias, 50 cascas de ovos foram mensuradas por meio de microscópio estereoscópico e sistema de análise de imagem QWin. A análise estatística foi efetuada utilizando o teste t-Student, não pareado no programa INSTAT. A largura, o comprimento e o diâmetro da abertura opercular das cascas de ovos de uma colônia silvestre foram maiores que de duas colônias laboratoriais de P. megistus.

The objective of the study was to evaluate the measurements of eggshells from three colonies of P. megistus, two from the lab and one from a sylvatic habitat. Fifty eggshells from each colony were measured with the use of a stereoscopic microscope and the Qwin image analysis system,. The statistical analysis was performed using unpaired t-test in INSTAT program. The length, width and diameter of the opercular opening of the eggshells from the sylvatic colony were larger than the two laboratorial colonies of P. megistus.

OBJETIVO: Estudar morfologicamente ovos de T. circummaculata e T. rubrovaria. MÉTODOS: Quarenta ovos das duas espécies foram mensurados por meio de projetor de perfil Nikon modelo 6C, e utilizado o teste Student, para execução da análise estatística. As observações morfológicas foram feitas em microscópio eletrônico de varredura JEOL, modelo JSM-T330A. RESULTADOS/CONCLUSÕES: A análise estatística revelou que os ovos e as cascas de ovos de T. rubrovaria são significativamente maiores que os de T. circummaculata. Observações microscópicas mostraram que a borda corial, assim como a goteira espermática, são bem mais evidentes nos ovos de T. rubrovaria que nos de T. circummaculata. O exocório das duas espécies é formado por áreas poligonais, que são hexagonais em sua maioria. Foram observados também o momento da eclosão do embrião e os detalhes das exúvias embrionárias.

OBJECTIVE: To study morphologically the eggs of T. circummaculata and T. rubrovaria. METHODS: Forty eggs of the two species were measured through Nikon model 6C profile projector. Student test was utilized for the statistical analysis and scanning electron microscopy for the morphological study of the eggs. RESULTS/CONCLUSIONS: The statistical analysis shows that the T. rubrovaria eggs are larger that those of T. circummaculata. Microscopical observations revealed that the chorial rim and the spermatic groove are less evident in T. circummaculata than in T. rubrovaria. Both species, the majority of exochorion cells are hexagonal. It was also observed the embryo eclosion and details of the embryonic molt.

OBJETIVO: Estudar morfologicamente ovos de T. circummaculata e T. rubrovaria. MÉTODOS: Quarenta ovos das duas espécies foram mensurados por meio de projetor de perfil Nikon modelo 6C, e utilizado o teste Student, para execução da análise estatística. As observações morfológicas foram feitas em microscópio eletrônico de varredura JEOL, modelo JSM-T330A. RESULTADOS/CONCLUSÕES: A análise estatística revelou que os ovos e as cascas de ovos de T. rubrovaria são significativamente maiores que os de T. circummaculata. Observações microscópicas mostraram que a borda corial, assim como a goteira espermática, são bem mais evidentes nos ovos de T. rubrovaria que nos de T. circummaculata. O exocório das duas espécies é formado por áreas poligonais, que são hexagonais em sua maioria. Foram observados também o momento da eclosão do embrião e os detalhes das exúvias embrionárias.

OBJECTIVE: To study morphologically the eggs of T. circummaculata and T. rubrovaria. METHODS: Forty eggs of the two species were measured through Nikon model 6C profile projector. Student test was utilized for the statistical analysis and scanning electron microscopy for the morphological study of the eggs. RESULTS/CONCLUSIONS: The statistical analysis shows that the T. rubrovaria eggs are larger that those of T. circummaculata. Microscopical observations revealed that the chorial rim and the spermatic groove are less evident in T. circummaculata than in T. rubrovaria. Both species, the majority of exochorion cells are hexagonal. It was also observed the embryo eclosion and details of the embryonic molt.