Dados do Trabalho

Título

Study of lipid metabolism of Biomphalaria glabrata snails during Schistosoma mansoni infection

Introdução

The development of the Schistosoma mansoni cycle in planorbid molluscs of the genus Biomphalaria, requires incorporation and use of different macromolecules, such as carbohydrates, proteins and lipids, from its hosts. Lipids are macromolecules not synthesized by the parasite, being mandatory for its incorporation.

Objetivo (s)

The objectives of this work were (i) to analyze the changes in the lipid profile of B.glabrata (BH) infected by S.mansoni (BH), by means of thin layer chromatography (TLC) of tissues linked to transport and metabolism (hemolymph and digestive gland) during intramollusc development of S. mansoni and (ii) to study the uptake and incorporation of fatty acids by cercariae during their development.

Material e Métodos

We used 10 infected snails and controls divided into 5 independent experiments, where both hemolymph and digestive gland were collected 7 weeks after infection. Intramollusc and newly released cercariae were studied using the fatty acid, palmitic acid, radiolabeled with tritium (³H-PA). Samples of B. glabrata 21 days after infection were injected with ³H-PA in the pericardium region. After 14 days of injection (35 days of infection), cercariae were collected by exposing the snails to artificial light for one hour. We observed an increase in the free fatty acids in the second week after infection.

Resultados e Conclusão

In the digestive gland, it was possible to observe a significant increase in triacylglycerols in the fourth week and in fatty acids in the third and fourth weeks after infection. When recent released cercariae were incubated with ³H-PA it showed a maximum peak of incorporation around 2 hours after incubation. Those fatty acids were used as precursors for the synthesis of different lipids classes such as esterified cholesterol, triacylglycerol, diacylglycerol and phospholipids. This incorporation of fatty acid was also evidenced during the development of the cercariae inside the sporocyst. The parasite incorporated the snail fatty acids to synthesize esterified cholesterol, triacylglycerol and a huge amount of phospholipids, mainly phosphatidylcholine and phosphatidylethanolamine. These data showed the manipulation of lipid transport and metabolism in the intermediate host by the parasite during its development. The incorporated fatty acids possibly provide the lipid supply ensuring the success of cercariae transformation into schistosomula. These lipid supplies are important for the parasite's life cycle during infection in the definitive host.

Palavras-chave

Lipid Esquistossomose

Agradecimentos

CNPq