Investigation of Rhodnius prolixus head anatomy using microtomography.

In the last years, microtomography has proved to be a powerful technique on insects' studies, allowing a detailed view of the structures' internal with a high resolution. One of the most important advantages about the use of microtomography in these studies is the fact that the dissection is not necessary, which decreases considerably the number of samples used on the insects' research. Some insects are used constantly in studies about morphology, metamorphosis, and reproduction, because they work as a model for others, and Rhodnius prolixus is one of the most studied in this group. This insect is also one of the main insect vectors of Chagas disease that kills around 12,000 people every year in Latin America. Some studies using laboratory microtomography conventional scanners combining with the correct staining methods have proved that it could be a powerful tool in biological research, allowing the visualisation of low-density tissues. The main goal of the present work was to use staining protocols to study Rhodnius prolixus with laboratory microtomography conventional scanners. The experiments were carried out at the imaging lab in the Theoretical Biology Department, University of Vienna, using an Xradia MicroXCT and at the University of Oslo, using a Skyscan 2211.

Impact of Trypanosoma cruzi on antimicrobial peptide gene expression and activity in the fat body and midgut of Rhodnius prolixus.

BACKGROUND: Rhodnius prolixus is a major vector of Trypanosoma cruzi, the causative agent of Chagas disease in Latin America. In natural habitats, these insects are in contact with a variety of bacteria, fungi, virus and parasites that they acquire from both their environments and the blood of their hosts. Microorganism ingestion may trigger the synthesis of humoral immune factors, including antimicrobial peptides (AMPs). The objective of this study was to compare the expression levels of AMPs (defensins and prolixicin) in the different midgut compartments and the fat body of R. prolixus infected with different T. cruzi strains. The T. cruzi Dm 28c clone (TcI) successfully develops whereas Y strain (TcII) does not complete its life- cycle in R. prolixus. The relative AMP gene expressions were evaluated in the insect midgut and fat body infected on different days with the T. cruzi Dm 28c clone and the Y strain. The influence of the antibacterial activity on the intestinal microbiota was taken into account. METHODS: The presence of T. cruzi in the midgut of R. prolixus was analysed by optical microscope. The relative expression of the antimicrobial peptides encoding genes defensin (defA, defB, defC) and prolixicin (prol) was quantified by RT-qPCR. The antimicrobial activity of the AMPs against Staphylococcus aureus, Escherichia coli and Serratia marcescens were evaluated in vitro using turbidimetric tests with haemolymph, anterior and posterior midgut samples. Midgut bacteria were quantified using colony forming unit (CFU) assays and real time quantitative polymerase chain reaction (RT-qPCR). RESULTS: Our results showed that the infection of R. prolixus by the two different T. cruzi strains exhibited different temporal AMP induction profiles in the anterior and posterior midgut. Insects infected with T. cruzi Dm 28c exhibited an increase in defC and prol transcripts and a simultaneous reduction in the midgut cultivable bacteria population, Serratia marcescens and Rhodococcus rhodnii. In contrast, the T. cruzi Y strain neither induced AMP gene expression in the gut nor reduced the number of colony formation units in the anterior midgut. Beside the induction of a local immune response in the midgut after feeding R. prolixus with T. cruzi, a simultaneous systemic response was also detected in the fat body. CONCLUSIONS: R. prolixus AMP gene expressions and the cultivable midgut bacterial microbiota were modulated in distinct patterns, which depend on the T. cruzi genotype used for infection.

Immunogenic activity of the fish tapeworm Pterobothrium heteracanthum (Trypanorhyncha: Pterobothriidae) in BALB/c mice.

The aim of this study was to verify the immunogenicity of Pterobothrium heteracanthum (Cestoda: Trypanorhyncha) crude protein extract (PH-CPE) in BALB/c mice. The parasites were obtained from Micropogonias furnieri (Osteichthyes: Sciaenidae). Groups of six mice were each immunized with 10, 50 or 100 µg of PH-CPE, on days 0 and 35. Both specific IgG and IgE responses were developed after immunization. The immunoblot assay revealed that specific IgG recognizes PH-CPE proteins with two molecular weight ranges, 60-75 and 30-40 kDa, and that IgE recognizes larger proteins over 120 kDa. This appears to be the first report on the immunogenicity of metacestodes within the Pterobothriidae and that PH-CPE is a potential inducer of a specific IgE response.

Frequência de enteroparasitas em amostras fecais de cães e gatos dos municípios do Rio de janeiro e Niterói / Frequency of enteric parasites in fecal samples of dogs and cats in Rio de Janeiro and Niterói

Foram analisadas 252 amostras de fezes de cães e gatos provenientes dos municípios do Rio de Janeiro e Niterói no período de 1999 a 2000. Foram 212 (84,12

Freqüência de enteroparasitas em amostras fecais de cães e gatos dos municípios do Rio de Janeiro e Niterói

Foram analisadas 252 amostras de fezes de cães e gatos provenientes dos municípios do Rio de Janeiro e Niterói no períodode 1999 a 2000. Foram 212 (84,12%) amostras de cães e 40 (15,87%) de gatos. Do total de amostras examinadas 81(32,14%), foram positivas para pelo menos uma espécie de parasita. Dos 212 exames de material fecal canino, 70 (33,01%)estavam positivos e de felinos 11 (27,5%). As infecções mistas foram observadas em 10 amostras caninas (14,28%) e quatrofelinas (36,36%). Nas amostras caninas, ovos de ancilostomídeos foram os mais encontrados em 43 (61,43%) amostras,enquanto os coccídeos foram mais freqüentemente observados nas fezes de felinos em três (27,27%) amostras. Quanto àidade dos animais, 37 (52,85%) amostras positivas eram provenientes de animais com mais de 1 ano de idade, indicandoprovável vermifugação dos filhotes, enquanto nos gatos a faixa etária mais parasitada foi de menos de seis meses, com 7(63,63%) positivos.