Abstract
Calcium is considered an essential element for the metabolism of aquatic snail Biomphalaria glabrata (Say, 1818), intermediate host of Schistosoma mansoni Sambon, 1907 in Brazil, and represents a limiting factor to its distribution and adaptation to the environment. This study investigated the effect of different concentrations of exogenous CaCO3 on the energetic metabolism of B. glabrata for better understanding the physiological interference of chemical elements dissolved in the environment with the physiology of this species. Sixty-day-old snails were distributed into six groups, five exposed to different concentrations of CaCO3 (20, 40, 60, 80 and 100 mg/L) and a control group. The exposure to CaCO3 was assessed over time, with analysis of 15 snails of each group in the following intervals: 1, 14, 21 or 30 days for hemolymph extraction. Concentrations of calcium and glucose in the hemolymph were determined by commercial kits, and organic acids were extracted using an ion exchange column and analyzed by high-performance liquid chromatography. Concentration of calcium in the hemolymph showed no significant difference (p>0.05) from the control group and between the concentrations tested. Concentration of glucose decreased (p<0.05) in the treatments of exposure to 20 and 40 mg/L and increased when exposed to 80 and 100 mg/L CaCO3 compared to control and to other concentrations tested over 30 days. The organic acids pyruvate, oxaloacetate, citrate, succinate, fumarate, beta-hydroxybutyrate and lactate presented increased concentrations, while propionate and acetoacetate, decreased concentrations, when exposed to CaCO3 compared to control. Considering the influence of different periods of exposure to CaCO3, on the 14th day, there were stronger alterations in the metabolism of B. glabrata. In conclusion, exposure to CaCO3 reduced the concentration of glucose, which is metabolized into pyruvate, the final product of glycolysis, and also influenced the energetic metabolism pathways, indicating an aerobic or partially anaerobic functioning.
Highlights
Biomphalaria glabrata (Say, 1818), the main intermediate host of Schistosoma mansoni Sambon, 1907 in Brazil, is a model for ecologic, toxicological and parasitological studies, since it occupies a high trophic level and is a food resource for several organisms (Barbosa and Barbosa, 1994; Paraense, 1970)
Snails are good bioindicators of contamination of freshwater environments (Cantinha et al, 2010; Carvalho et al, 1988), as they are sensitive to environmental alterations, such as chemical elements dissolved in the water, hydrography, soil composition, climate and physical geography (Abílio et al, 2007; Guerino et al, 2009)
Results pH values of the solutions with 20, 40, 60, 80 and 100 mg CaCO3 were analyzed. These solutions presented pH 8.5 in 20 mg, 9.0 in the other concentrations of CaCO3 and 8.0 in the control water. pH values in the hemolymph of snails exposed to different concentrations of CaCO3 was 8.0 when exposed to all concentrations; the pH of the control group was 7.0
Summary
Biomphalaria glabrata (Say, 1818), the main intermediate host of Schistosoma mansoni Sambon, 1907 in Brazil, is a model for ecologic, toxicological and parasitological studies, since it occupies a high trophic level and is a food resource for several organisms (Barbosa and Barbosa, 1994; Paraense, 1970). Snails are good bioindicators of contamination of freshwater environments (Cantinha et al, 2010; Carvalho et al, 1988), as they are sensitive to environmental alterations, such as chemical elements dissolved in the water, hydrography, soil composition, climate and physical geography (Abílio et al, 2007; Guerino et al, 2009). Chemical elements such as calcium, copper, iron, zinc and manganese are essential to the metabolism of such organisms (Barbosa and Barbosa, 1994). It is important as a cofactor for enzymes involved in glycolysis and tricarboxylic acid (TCA) cycle pathways (Becker, 1980; Tunholi et al, 2011) and as a component of buffer solutions
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