The mineralized shell (consisting of calcium carbonate) of the tropical freshwater snail Biomphalaria glabrata was investigated with high resolution synchrotron X-ray powder diffractometry and X-ray absorption spectroscopy (EXAFS). Parts from different locations of the snail shell were taken from animals of different age grown under various keeping conditions. Additionally, eggs with ages of 60, 72, 120, and 140 hours were examined. Traces of aragonite were found as first crystalline phase in 120 h old eggs, however, Ca K-edge EXAFS indicated the presence of aragonitic structures already in the X-ray amorphous sample of 72 h age. The main component of the shell of adult animals was aragonite in all cases, but in some cases minor amounts of vaterite (below 1.5%) are formed. The content of vaterite is generally low in the oldest part of the shell (the center) and increases towards the mineralizing zone (the shell margin). In juvenile snails, almost no vaterite was detectable in any part of the shell.

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Background: Schistosomiasis is one of the major health problems in tropical and sub-tropical countries, with school age children usually being the most affected group. In 1998 the Department of Health of the province of KwaZulu-Natal established a pilot programme for helminth control that aimed at regularly treating primary school children for schistosome and intestinal helminth infections. This article describes the baseline situation and the impact of treatment on S. haematobium infection in a cohort of schoolchildren attending grade 3 in a rural part of the province.

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Sulfated carbohydrates may play a role in the biomineralization of the molluscan shell. The carbohydrates of the extracted water-insoluble organic shell matrix (IM) of the freshwater snail Biomphalaria glabrata were identified as glucose, mannose, galactose, and N-acetyl-glucosamine, whereas the water-soluble organic matrix (SM) additionally contained N-acetyl-galactosamine. A specific lectin binding pattern of the matrix was obtained. One prominent protein of the SM, with a size of 19.6 kDa and a pI of 7.4, was shown to be a glycoprotein with terminal glucosyl or mannosyl moieties. The acidic constitutents of the matrix showed a variety of possible terminal sugars, indicating a heterogenous mixture of proteoglycans or glycosaminoglycans (GAGs) and glycoproteins. At the shell-forming mantle edge, an alcian-blue-positive material was observed in the periostracum groove (PG), the belt, and apically in the cells of the outer mantle epithelium (OME). With the help of lectins, all sugars in question were detected in the PG and the belt, whereas the OME was bound by glucose/mannose- and GlcNac-specific lectins only. Although the complete set of GAGs will be produced in the PG and the belt, a very acidic fraction of GAGs and the 19.6-kDa protein can also be delivered by the OME.