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Profile of metabolite and biomolecule concentrations in the hemolymph of Bulinus globosus and Bulinus rohlfsi under aestivation and starvation
Abstract
There is resurgence in epidemiology of schistosomiasis in Nigeria with attendant socio-economic and health impact. The agents perpetuating this disease are the Bulinus snails which employ aestivation to survive unfavourable conditions. These snails are intermediate hosts required for the aquatic stage of schistosomes thereby increasing their chances of returning to an aquatic environment to resume life cycle once favourable conditions reappear. However, mechanism of aestivation under
aridity and drought is not clear. This study therefore, investigated the effects of aestivation and starvation on endogenous metabolic reserves in tissues and haemolymph of two snail species namely Bulinus globosus (Morelet) and Bulinus rohlfsi (Clessin). Aestivation, starvation, and control experiments were set up for 30 days by placing three groups of snails in
standard aestivation slope, aquarium and control slope containing mixture of sand and clay (3:1) in slopes and water only for aquarium. Snails were fed on lettuce (Lactuca sativa) ad libitum for 28 days until water completely drained out. The aestivation slope and aquarium were left dry for another 30 days without lettuce while the control slope contained both lettuce and water. Quantitative analysis of protein, carbohydrate and lipid were determined in tissues and hemolymph while hemolymph creatinine,
urea, total protein, glucose, total cholesterol and triglyceride were determined in aestivating, starved and control snails. Activities of lipases a-amylase alanine amino transferase (ALT) and aspartate amino transferase (AST) were determined. Data were analysed using ANOVA.Tissue macromolecules decreased in aestivating and starving snails during aestivation compared with control. Lipid and carbohydrate were significantly reduced in aestivating B. globosus and B. rohlfsi during aestivation (p<0.05). In aestivating and starving B.globosus, haemolymph creatinine, urea, total protein, glucose, ALT and AST were significantly decreased while haemolymph total cholesterol, triglyceride and a-amylase concentrations and activity increased significantly (p<0.05 ). In B.rohlfsi, creatinine, urea, ALT and AST were significantly decreased compared with control (p<0.05). There was an increase in lipase activity during aestivation suggesting lipolysis. B. globosus and B. rohlfsi possess ability to survive unfavourable conditions by economical utilisation of stored metabolites thus enabling them to carry infection from one season to another. B. globosus seems a better aestivator than B. rohlfsi in terms of physiological adaptations to aestivation induced stress.
aridity and drought is not clear. This study therefore, investigated the effects of aestivation and starvation on endogenous metabolic reserves in tissues and haemolymph of two snail species namely Bulinus globosus (Morelet) and Bulinus rohlfsi (Clessin). Aestivation, starvation, and control experiments were set up for 30 days by placing three groups of snails in
standard aestivation slope, aquarium and control slope containing mixture of sand and clay (3:1) in slopes and water only for aquarium. Snails were fed on lettuce (Lactuca sativa) ad libitum for 28 days until water completely drained out. The aestivation slope and aquarium were left dry for another 30 days without lettuce while the control slope contained both lettuce and water. Quantitative analysis of protein, carbohydrate and lipid were determined in tissues and hemolymph while hemolymph creatinine,
urea, total protein, glucose, total cholesterol and triglyceride were determined in aestivating, starved and control snails. Activities of lipases a-amylase alanine amino transferase (ALT) and aspartate amino transferase (AST) were determined. Data were analysed using ANOVA.Tissue macromolecules decreased in aestivating and starving snails during aestivation compared with control. Lipid and carbohydrate were significantly reduced in aestivating B. globosus and B. rohlfsi during aestivation (p<0.05). In aestivating and starving B.globosus, haemolymph creatinine, urea, total protein, glucose, ALT and AST were significantly decreased while haemolymph total cholesterol, triglyceride and a-amylase concentrations and activity increased significantly (p<0.05 ). In B.rohlfsi, creatinine, urea, ALT and AST were significantly decreased compared with control (p<0.05). There was an increase in lipase activity during aestivation suggesting lipolysis. B. globosus and B. rohlfsi possess ability to survive unfavourable conditions by economical utilisation of stored metabolites thus enabling them to carry infection from one season to another. B. globosus seems a better aestivator than B. rohlfsi in terms of physiological adaptations to aestivation induced stress.
