943 resultados para vertebrate hosts


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Hosts of Trigonalidae include larvae of social paper wasps, which have been considered secondary hosts, supposedly following predation of the primary host (usually caterpillars) by adult wasps. This study provides observations on biological aspects of the parasitism of Apoica flavissima Van der Vecht by Seminota marginata (Westwood), and suggests that social wasps may be both primary and secondary hosts, whereas they extract and chew vegetable fiber.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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The neural retina is a highly complex tissue composed of excitatory and inhibitory neurons and glial cells. Glutamate, the main excitatory neurotransmitter, mediates information transfer from photoreceptors, bipolar cells, and ganglion cells, whereas interneurons, mainly amacrine and horizontal cells, use γ-aminobutyric acid (GABA), the main inhibitory neurotransmitter. In this review we place an emphasis on glutamate and GABA transporters as highly regulated molecules that play fundamental roles in neurotransmitter clearance, neurotransmitter release, and oxidative stress. We pharmacologically characterized glutamate transporters in chicken retina cells and identified two glutamate transporters: one Na+-dependent transporter and one Na+-independent transporter. The Na+-dependent uptake system presented characteristics related to the high-affinity xAG- system (EAAT1), and the Na+-independent uptake system presented characteristics related to the xCG- system, which highly contributes to glutamate transport in the retina. Glutamate shares the xCG- system with another amino acid, L-cysteine, suggesting the possible involvement of glutathione. Both transporter proteins are present mainly in Müller glial cells. GABA transporters (GATs) mediate high-affinity GABA uptake from the extracellular space and terminate the synaptic action of GABA in the central nervous system. GABA transporters can be modulated by molecules that act on specific sites to promote transporter phosphorylation and dephosphorylation. In addition to a role in the clearance of GABA, GATs may also release GABA through a reverse transport mechanism. In the chicken retina, a GAT-1 blocker, but not GAT2/3 blocker, was shown to inhibit GABA uptake, suggesting that GABA release from retina cells is mainly mediated by a GAT-1-like transporter.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Endo-oligopeptidase A, EC 3.4.22.19, converts small enkephalin-containing peptides into the corresponding enkephalins in vitro. We investigated the presence of endooligopeptidase A in the retina and its possible colocalization with enkephalins in retinal neurons. The specific activity of endo-oligopeptidase A found in pigeon retinae (30.3 +/- 7.3 mU/mg, mean +/- standard deviation) was four times higher than in rabbit retinae (7.0 +/- 1.1 mU/mg). The enzyme activity was not modified by EDTA, but it was enhanced by dithiothreitol and inhibited by zinc and 5,5'-dithiobis(2-nitrobenzoic acid). Immunohistochemical experiments with a purified antiserum against rabbit endo-oligopeptidase A revealed labeled neurons in both the inner nuclear layer and the ganglion cell layer of pigeon and rabbit retinae. Double-labeling immunofluorescence experiments demonstrated that about 90% of neurons containing endo-oligopeptidase A-like immunoreactivity also contained [Leu5]-enkephalin-like immunoreactivity. These colocalization results may represent an important step toward the demonstration of the possible involvement of endo-oligopeptidase A in enkephalin generation in vivo.

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The platinosomiase is a disease the hepatobiliary system of domestic felines being caused by trematode Platynosomum fastosum. The life cycle of the parasite includes the presence of three intermediate hosts (snails, terrestrial isopodes, lizards or frogs). The cat is considered definitive host of the parasite and acquires the infection eating a vertebrate intermediate host containing metacercariae. The adult parasites generally inhabit the liver, gallbladder and bile ducts of cats. The severity of clinical manifestations depends mainly on the number of flukes in the biliary tract. Many animals are asymptomatic or exhibit nonspecific clinical manifestations such as anorexia, lethargy, weight loss, vomiting and diarrhea. In large infestations can occur biliary obstruction resulting in jaundice, cirrhosis, hepatitis cholangiohepatitis and even death. The definitive diagnosis is accomplished through by the detection of fluke eggs in feces or through laparotomy and liver biopsy. Treatment should be based on the use of anthelmintic for the elimination of the parasite and supportive therapy for the animal. Prevention is difficult due to predatory nature of the cat. The control can be accomplished through periodic fecal examinations

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)