The relation of the physical chemistry of water and physiology of the snail vectors of Bilharzia

Specimens of Biomphalaria pfeifferi, vector of Schistosoma mansoni, and Bulinus (Physopsis) globosus, vector of S. haematobium, were collected from aquatic habitats in Central Africa, with a medium quality of water hardness and alkalinity (Ca++ 12 mg/L & HCO3- 40 mg. /L). These snails were cultured in the laboratory through several generations, in waters of a soft (Ca++ 2 mg/L; HCO3- 15 mg/L), medium (Ca++ 10 mg/L; HCO3- 47 mg/L) and hard quality (Ca++ 75 mg/L; HCO3- 320 mg/L)

Seven protein fractions of the perivitelline fluid of B. pfeifferi, reared in soft, medium and hard waters, were separated by electrophoresis and significant differences at P<0.05 were found in the relative concentrations of 3 fractions. Thin layer chromatography of the hydrolysed egg protein of B. pfeifferi showed 10 amino acids present, but no significant differences in amino acid concentration were found in egg protein from soft, medium and hard waters. Thin layer chromatography of the hydrolysed shell protein of both B. (Ph.) globosus and B. pfeifferi from soft, medium and hard waters showed 17 amino acids, and significant differences in concentration of 5 amino acids were found between the shell protein from the different waters.