Resumen de Physiological interaction between Echinostoma Paraensei (Trematoda, Echinostomatidae) and its first intermadiate host Biomphalaria Glabrata (Mollusca, Gastropodo)
Victor Tunholi, Vinícius Menezes Tunholi Alves, Arnaldo Maldonado Jr, Maria de Lurdes de A. Rodrigues, Jairo Pinheiro
The egg-laying rate, number of egg masses, number of eggs/mass, number of eggs hatched/snail and egg viability of Biomphalaria glabrata exposed to different doses (5 and 50) of Echinostoma paraensei miracidia were analyzed as indicators of reproductive activity. On average there was an increase in the parameters evaluated in the infected snails in relation to the controls (uninfected snails), except for egg viability, which was significantly lower in the groups infected with 50 miracidia. The effect of infection by E. paraensei on the activity of the enzymes alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and the concentration of total proteins, uric acid and urea in the hemolymph of B. glabrata were investigated after exposure to five or 50 miracidia. There was a significant decrease in the concentrations of total proteins in the snails exposed both to five and 50 miracidia, as well as an increase in the nitrogenous products of excretion, ALT and AST activities. The higher ALT activity in the hemolymph of the snails after infection with 50 miracidia suggests highest energetic requirement in these snails in relation to snails exposed to five miracidia. The results also suggest an increase in the use of total proteins, since there was increased formation of nitrogenous catabolites, in conformity with an increase in the aminotransferase activities, frequently associated with tissue damages. The effect of experimental exposure of B. glabrata to different doses (5 and 50) of E. paraensei miracidia on the total levels of cholesterol and triglycerides circulating in the hemolymph and the neutral lipids in the digestive gland�gonad (DGG) complex were studied. The reduced levels of these lipids in the infected snails indicate intense use of these substrates both by the intermediate host and the parasite, suggesting its probable participation in the energy metabolism and structural construction of the developing larval stages. Alterations in the profile of neutral lipids in the DGG were also found. The results obtained indicate that in this model, the lipid metabolism depends on the miracidial dose used.
