RESUMO

Lectins are ubiquitous proteins involved in the immune defenses of different organisms and mainly responsible for non-self-recognition and agglutination reactions. This work describes molecular and biological characterization of a rhamnose-binding lectin (RBL) from Rhodnius prolixus, which possesses a 21 amino acid signal peptide and a mature protein of 34.6 kDa. The in-silico analysis of the primary and secondary structures of RpLec revealed a lectin domain fully conserved among previous insects studied. The three-dimensional homology model of RpLec was similar to other RBL-lectins. Docking predictions with the monosaccharides showed rhamnose and galactose-binding sites comparable to Latrophilin-1 and N-Acetylgalactosamine-binding in a different site. The effects of RpLec gene silencing on levels of infecting Trypanosoma cruzi Dm 28c and intestinal bacterial populations in the R. prolixus midgut were studied by injecting RpLec dsRNA into the R. prolixus hemocoel. Whereas T. cruzi numbers remained unchanged compared with the controls, numbers of bacteria increased significantly. The silencing also induced the up regulation of the R. prolixus defC (defensin) expression gene. These results with RpLec reveal the potential importance of this little studied molecule in the insect vector immune response and homeostasis of the gut bacterial microbiota.

Assuntos

RESUMO

Many previous studies have shown a great phylogenetic and biological variability of Trypanosoma cruzi using different molecular and biochemical methods. Populations of T. cruzi were initially clustered into two main lineages called TcI and TcII by the size of the mini-exon PCR product. In the present study, 33 isolates derived from three triatomine taxa, which belong to the Triatoma brasiliensis species complex (Triatoma juazeirensis, Triatoma melanica and Triatoma sherlocki); collected in three distinct areas of Bahia state were characterized by PCR. The isolates were identified by the size of the mini-exon gene, 18S rRNA and 24Sα rRNA amplicons. T. cruzi isolates obtained in sylvatic and intradomiciliar ecotopes, derived from T. juazeirensis and T. melanica, were identified as TcI while the parasites originated from T. sherlocki were characterized as TcI and TcII genotypes, respectively. Those species are present in sylvatic ecotopes but are able to infest intradomiciliar areas. Therefore, it would be important to maintain studies in those localities of Bahia and further investigate the possibilities of Chagas disease transmission. Human disease may occur by any T. cruzi genotype and not only by TcII as it is the case in Amazonia.

Assuntos

RESUMO

The present study aimed to evaluate the efficiency of hypertonic saline solution (HSS) as a novel treatment of acute ruminal lactic acidosis (ARLA) in cattle, focusing on urinary excretion of acids. Twelve cannulated steers were submitted to experimentally induced ARLA by adminis- tering sucrose into the rumen. Twenty hours later, the cattle were randomly divided into two equal groups. The first group was treated with 7.5% HSS (5 mL/kg) over 15 min, and isotonic saline solution (ISS; 20 mL/kg) for the subsequent 165 minutes. The control group was administered ISS instead of HSS. Rumen and urine samples were collected at different times during the experiment from the baseline to 64 h post-induction. The induction caused a medium-to-moderate ruminal acidosis, and a moderate degree of systemic acidosis and dehydration. Steers treated with HSS increased by 50% its glomerular filtration rate (1.61 mL/min) compared to ISS group (1.06 mL/ min; p⟨0.03). The overall volume of urine excreted by HSS group was higher than that in ISS group (1.62 L vs 0.7 L; p⟨0.02). This increase in total volume of urine provided by HSS favored a greater excretion of H+ ions in urine, which was 3.39-fold higher in HSS group (64.3*10-7 vs 18.9*10-7 Mol) as well as lactate (241.7 vs 181.8 mMol) and P urinary excretion (3.8 vs 1.1 mMol) that reduced the urine pH (5.3 vs 5.7). Only the HSS group decreased significantly blood total lactic acid concentration (20.3 %) throughout the treatment. A positive relationship was found between the excretion of urinary phosphorus and urinary pH (r2=0.562). The results showed that this novel treatment with HSS enhanced renal excretion of acids and may be recommended as an additional treatment for cattle with lactic acidosis.

Assuntos

RESUMO

Helminth infections have the ability to modulate host's immune response through mechanisms that allow the chronic persistence of the worms in the host. Here, we investigated the mechanisms involved on the suppressive effect of Ascaris suum infection using a murine experimental model of LPS-induced inflammation. We found that infection with A. suum markedly inhibited leucocyte influx induced by LPS into air pouches, suppressed secretion of pro-inflammatory cytokines (IL-1ß, TNF-α and IL-6) and induced high levels of IL-10 and TGF-ß. Augmented frequency of CD4+ CD25high Foxp3+ T cells was observed in the mesenteric lymph nodes of infected mice. Adoptive transfer of purified CD4+ CD25+ T cells to recipient uninfected mice demonstrated that these cells were able to induce a suppressive effect in the LPS-induced inflammation in air pouch model. In addition, adoptive transfer of CD4+ CD25+ T cells derived from IL-10 knockout mice suggests that this suppressive effect of A. suum infection involves IL-10 cytokine. In conclusion, our results demonstrated that A. suum experimental infection was capable of suppressing LPS-induced inflammation by mechanisms, which seem to be dependent on responses of CD4+ CD25+ T cells and secretion of IL-10 cytokine.

Assuntos

RESUMO

Abstract Satellite images are an effective tool for the detection of phytoplankton blooms, since they cause striking changes in water color. Bloom intensity can be expressed in terms of chlorophyll-a concentration. Previous studies suggest the use of Landsat TM4/TM3 reflectance ratio to retrieve surface chlorophyll-a concentration from aquatic systems. In this study we assumed that a remote sensing trophic state index can be applied to investigate how changes in HRT along the hydrologic year affect the spatial distribution of the phytoplankton blooms at Ibitinga’s reservoir surface. For that, we formulated two objectives: (1) apply a semi-empirical model which uses this reflectance ratio to map chlorophyll-a concentration at Ibitinga reservoir along the 2005 hydrologic year and (2) assess how changes in hydraulic residence time (HRT) affect the spatial distribution of phytoplankton blooms at Ibitinga Reservoir. The study site was chosen because previous studies reported seasonal changes in the reservoir limnology which might be related to the reservoir seasonality and hydrodynamics. Six Landsat/TM images were acquired over Ibitinga reservoir during 2005 and water flow measurements provided by the Brazilian Electric System National Operator - ONS were used to compute the reservoir´s residence time, which varied from 5.37 to 52.39 days during 2005. The HRT in the date of image acquisition was then compared to the distribution of chlorophyll-a in the reservoir. The results showed that the HRT increasing implies the increasing of the reservoir surface occupied by phytoplankton blooms.

Resumo As imagens de satélite são frequentemente usadas para a identificação de florações de fitoplâncton porque sua presença causa mudanças significativas na cor da água. A abundância das florações pode ser quantificada por medidas de concentração de clorofila-a. Diversos estudos sugerem o uso da razão de reflectância das bandas TM4/TM3 Landsat, para determinar as concentrações de clorofila-a em sistemas aquáticos. Este trabalho tem como objetivos: (1) aplicar um modelo semi-empírico que usa essa razão para mapear a concentração de clorofila-a no reservatório de Ibitinga ao longo do ano hidrológico de 2005; (2) avaliar como as mudanças no tempo de residência hidráulica afetaram a distribuição de florações na superfície do reservatório. O reservatório de Ibitinga foi selecionado porque estudos prévios indicavam mudanças sazonais nas propriedades limnológicas do reservatório, as quais poderiam estar relacionadas à sazonalidade e à hidrodinâmica. Seis imagens TM/Landsat foram adquiridas sobre o reservatório de Ibitinga durante o ano de 2005. Foi então usada uma tabela associando intervalos de razão de banda a intervalos de concentração de clorofila-a. Medidas de vazão fornecidas pelo Operador Nacional do Sistema Elétrico – ONS foram utilizadas para calcular o tempo de residência hidráulica do reservatório, que variou entre 5,37 e 52,39 dias durante 2005. O tempo de residência hidráulica em cada data de aquisição da imagem foi então comparado com a área ocupada pelas florações de fitoplancton. Os resultados indicaram uma forte relação entre o tempo de residência hidráulica e a área ocupada por florações. Em junho de 2005, quando o reservatório atingiu seu menor tempo de residência hidráulica, apenas 20% de sua área estiveram ocupadas por florações. Em setembro e outubro, quando a residência hidráulica atinge o seu máximo, mais que 80% da superfície do reservatório foram ocupadas por florações de fitoplancton.

Assuntos

RESUMO

Satellite images are an effective tool for the detection of phytoplankton blooms, since they cause striking changes in water color. Bloom intensity can be expressed in terms of chlorophyll-a concentration. Previous studies suggest the use of Landsat TM4/TM3 reflectance ratio to retrieve surface chlorophyll-a concentration from aquatic systems. In this study we assumed that a remote sensing trophic state index can be applied to investigate how changes in HRT along the hydrologic year affect the spatial distribution of the phytoplankton blooms at Ibitingas reservoir surface. For that, we formulated two objectives: (1) apply a semi-empirical model which uses this reflectance ratio to map chlorophyll-a concentration at Ibitinga reservoir along the 2005 hydrologic year and (2) assess how changes in hydraulic residence time (HRT) affect the spatial distribution of phytoplankton blooms at Ibitinga Reservoir. The study site was chosen because previous studies reported seasonal changes in the reservoir limnology which might be related to the reservoir seasonality and hydrodynamics. Six Landsat/TM images were acquired over Ibitinga reservoir during 2005 and water flow measurements provided by the Brazilian Electric System National Operator - ONS were used to compute the reservoir´s residence time, which varied from 5.37 to 52.39 days during 2005. The HRT in the date of image acquisition was then compared to the distribution of chlorophyll-a in the reservoir. The results showed that the HRT increasing implies the increasing of the reservoir surface occupied by phytoplankton blooms.(AU)

As imagens de satélite são frequentemente usadas para a identificação de florações de fitoplâncton porque sua presença causa mudanças significativas na cor da água. A abundância das florações pode ser quantificada por medidas de concentração de clorofila-a. Diversos estudos sugerem o uso da razão de reflectância das bandas TM4/TM3 Landsat, para determinar as concentrações de clorofila-a em sistemas aquáticos. Este trabalho tem como objetivos: (1) aplicar um modelo semi-empírico que usa essa razão para mapear a concentração de clorofila-a no reservatório de Ibitinga ao longo do ano hidrológico de 2005; (2) avaliar como as mudanças no tempo de residência hidráulica afetaram a distribuição de florações na superfície do reservatório. O reservatório de Ibitinga foi selecionado porque estudos prévios indicavam mudanças sazonais nas propriedades limnológicas do reservatório, as quais poderiam estar relacionadas à sazonalidade e à hidrodinâmica. Seis imagens TM/Landsat foram adquiridas sobre o reservatório de Ibitinga durante o ano de 2005. Foi então usada uma tabela associando intervalos de razão de banda a intervalos de concentração de clorofila-a. Medidas de vazão fornecidas pelo Operador Nacional do Sistema Elétrico ONS foram utilizadas para calcular o tempo de residência hidráulica do reservatório, que variou entre 5,37 e 52,39 dias durante 2005. O tempo de residência hidráulica em cada data de aquisição da imagem foi então comparado com a área ocupada pelas florações de fitoplancton. Os resultados indicaram uma forte relação entre o tempo de residência hidráulica e a área ocupada por florações. Em junho de 2005, quando o reservatório atingiu seu menor tempo de residência hidráulica, apenas 20% de sua área estiveram ocupadas por florações. Em setembro e outubro, quando a residência hidráulica atinge o seu máximo, mais que 80% da superfície do reservatório foram ocupadas por florações de fitoplancton.(AU)

Assuntos

RESUMO

Satellite images are an effective tool for the detection of phytoplankton blooms, since they cause striking changes in water color. Bloom intensity can be expressed in terms of chlorophyll-a concentration. Previous studies suggest the use of Landsat TM4/TM3 reflectance ratio to retrieve surface chlorophyll-a concentration from aquatic systems. In this study we assumed that a remote sensing trophic state index can be applied to investigate how changes in HRT along the hydrologic year affect the spatial distribution of the phytoplankton blooms at Ibitinga's reservoir surface. For that, we formulated two objectives: (1) apply a semi-empirical model which uses this reflectance ratio to map chlorophyll-a concentration at Ibitinga reservoir along the 2005 hydrologic year and (2) assess how changes in hydraulic residence time (HRT) affect the spatial distribution of phytoplankton blooms at Ibitinga Reservoir. The study site was chosen because previous studies reported seasonal changes in the reservoir limnology which might be related to the reservoir seasonality and hydrodynamics. Six Landsat/TM images were acquired over Ibitinga reservoir during 2005 and water flow measurements provided by the Brazilian Electric System National Operator - ONS were used to compute the reservoir´s residence time, which varied from 5.37 to 52.39 days during 2005. The HRT in the date of image acquisition was then compared to the distribution of chlorophyll-a in the reservoir. The results showed that the HRT increasing implies the increasing of the reservoir surface occupied by phytoplankton blooms.

Assuntos

RESUMO

Abstract Satellite images are an effective tool for the detection of phytoplankton blooms, since they cause striking changes in water color. Bloom intensity can be expressed in terms of chlorophyll-a concentration. Previous studies suggest the use of Landsat TM4/TM3 reflectance ratio to retrieve surface chlorophyll-a concentration from aquatic systems. In this study we assumed that a remote sensing trophic state index can be applied to investigate how changes in HRT along the hydrologic year affect the spatial distribution of the phytoplankton blooms at Ibitingas reservoir surface. For that, we formulated two objectives: (1) apply a semi-empirical model which uses this reflectance ratio to map chlorophyll-a concentration at Ibitinga reservoir along the 2005 hydrologic year and (2) assess how changes in hydraulic residence time (HRT) affect the spatial distribution of phytoplankton blooms at Ibitinga Reservoir. The study site was chosen because previous studies reported seasonal changes in the reservoir limnology which might be related to the reservoir seasonality and hydrodynamics. Six Landsat/TM images were acquired over Ibitinga reservoir during 2005 and water flow measurements provided by the Brazilian Electric System National Operator - ONS were used to compute the reservoir´s residence time, which varied from 5.37 to 52.39 days during 2005. The HRT in the date of image acquisition was then compared to the distribution of chlorophyll-a in the reservoir. The results showed that the HRT increasing implies the increasing of the reservoir surface occupied by phytoplankton blooms.

Resumo As imagens de satélite são frequentemente usadas para a identificação de florações de fitoplâncton porque sua presença causa mudanças significativas na cor da água. A abundância das florações pode ser quantificada por medidas de concentração de clorofila-a. Diversos estudos sugerem o uso da razão de reflectância das bandas TM4/TM3 Landsat, para determinar as concentrações de clorofila-a em sistemas aquáticos. Este trabalho tem como objetivos: (1) aplicar um modelo semi-empírico que usa essa razão para mapear a concentração de clorofila-a no reservatório de Ibitinga ao longo do ano hidrológico de 2005; (2) avaliar como as mudanças no tempo de residência hidráulica afetaram a distribuição de florações na superfície do reservatório. O reservatório de Ibitinga foi selecionado porque estudos prévios indicavam mudanças sazonais nas propriedades limnológicas do reservatório, as quais poderiam estar relacionadas à sazonalidade e à hidrodinâmica. Seis imagens TM/Landsat foram adquiridas sobre o reservatório de Ibitinga durante o ano de 2005. Foi então usada uma tabela associando intervalos de razão de banda a intervalos de concentração de clorofila-a. Medidas de vazão fornecidas pelo Operador Nacional do Sistema Elétrico ONS foram utilizadas para calcular o tempo de residência hidráulica do reservatório, que variou entre 5,37 e 52,39 dias durante 2005. O tempo de residência hidráulica em cada data de aquisição da imagem foi então comparado com a área ocupada pelas florações de fitoplancton. Os resultados indicaram uma forte relação entre o tempo de residência hidráulica e a área ocupada por florações. Em junho de 2005, quando o reservatório atingiu seu menor tempo de residência hidráulica, apenas 20% de sua área estiveram ocupadas por florações. Em setembro e outubro, quando a residência hidráulica atinge o seu máximo, mais que 80% da superfície do reservatório foram ocupadas por florações de fitoplancton.

RESUMO

O presente trabalho avaliou os efeitos da administração de duas diferentes quantidades de melão sobre variáveis hemogasométricas, bioquímicas e hematológicas de ovinos não adaptados. Foram utilizados 12 ovinos canulados, pesando 25kg de peso vivo, que nunca receberam ração concentrada. Os animais receberam dieta à base de feno (2,3% do peso vivo) e água à vontade. Os ovinos foram distribuídos aleatoriamente em dois grupos e receberam 25% ou 75% da matéria seca (MS) da dieta de melão triturado (G25% e G75%, respectivamente) diretamente no rúmen. Foram realizadas coletas de sangue e determinação do pH ruminal nos seguintes tempos: zero, 3, 6, 12, 18 e 24 horas após oferecimento do melão. Foi realizada análise hemogasométrica, do volume globular, determinação da concentração plasmática de lactato-L, glicose e osmolaridade sérica. No G25%, o pH sanguíneo variou entre 7,40 e 7,31, enquanto o G75% apresentou pH entre 7,38 e 7,26. Maiores concentrações de glicose plasmática foram detectadas no G75% no T3, T6 e T12 (P<0,05). Os ovinos que receberam 25% de melão mantiveram parâmetros sanguíneos dentro da normalidade, ao passo que, no G75%, os ovinos apresentaram discreta acidose metabólica sistêmica e hiperglicemia. A suplementação com 25% de melão pode ser uma alternativa segura na alimentação de ovinos.

This study evaluated the effects of two different amounts of melon on blood gas, biochemical and hematological variables of sheep not adapted. We used 12 cannulated sheep weighing 25 kg which never received concentrate. The animals received hay-based diet (2.3% of body weight) and water ad libitum. The sheep were randomly divided into two groups and received 25% or 75% of the dry matter (DM) of the diet of crushed melon (G25% and G75%, respectively) directly into the rumen. Blood collection and determination of ruminal pH were made at the following times: zero, three, six, 12, 18 and 24 hours after administration of the fruit. In whole blood was performed blood gas analysis and packed cell volume; in the plasma it was determined the concentrations of L-Lactate and glucose and in the serum the osmolarity. At G25% the blood pH ranged between 7.40 and 7.31, while G75% showed pH between 7.38 and 7.26. Higher concentrations of plasma glucose were detected in G75% after 3, 6 and 12 hours (P <0.05). Sheep receiving 25% of melon showed blood parameters within the normal range, while in the G75%, sheep had a mild systemic metabolic acidosis and hyperglycemia.

Assuntos

RESUMO

Trypanosoma cruzi is the causative agent of Chagas disease, transmitted to humans and mammals by blood-sucking hemipteran insects belonging to the Triatominae subfamily. The two main genotypes of T. cruzi (TcI and TcII) differ in many characteristics concerning their genetic profile. Despite the extensive literature on vectors and the etiologic agent, several interactive aspects between these two elements of Chagas disease are still waiting to be further clarified. Here, biological and histological features resulting from the interaction between Albino Swiss mice and T. cruzi isolate PB913 after passages through vectors of the Triatoma brasiliensis species complex were evaluated. Comparing the four members of the T. brasiliensis species complex-Triatoma brasiliensis brasiliensis Neiva, Triatoma brasiliensis macromelasoma Galvão, Triatoma melanica Neiva & Lent, and Triatoma juazeirensis Costa & Felix-no significant differences in parasitemia of the infected mice were observed. At 20 days post-infection, the highest number of parasites was observed in the group of mice that were infected with parasites obtained from T. b. macromelasoma. Tropism of the parasites to different organs such as heart, bladder, and skeletal muscles followed by inflammatory cell infiltrates was observed with quantitative and qualitative differences. Even though the four members of the T. brasiliensis species complex differ in their geographical distribution, morphology, biology, ecology, and genetics, no significant influence on the parasitemia of the T. cruzi PB913 isolate was detected. After evaluation of the tissue samples, a higher pathogenicity of parasites obtained from T. b. brasiliensis was noticeable.

Assuntos