The range of concentration of calcium carbonate in the shells of various freshwater gastropods was determined using ion chromatography. Individuals of Helisoma trivolvis (wild) were collected from three ponds in Pennsylvania and New Jersey; individuals of Physa sp. were collected from one pond in New Jersey; individuals of H. trivolvis (Colorado strain) and Biomphalaria glabrata (NMRI strain) were raised in the laboratory; and individuals of Pomacea bridgesii were purchased commercially. The concentrations of calcium carbonate (mean % by dry weight) of the shells were as follows: H. trivolvis (wild), 97.0; Physa sp., 97.8; H. trivolvis (CO), 97.6; B. glabrata, 98.8; P. bridgesii, 98.2. Our data support and validate the previous claim that snail shells are comprised of 95-99.9% calcium carbonate.

Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used to study element ions in whole bodies of uninfected Biomphalaria glabrata snails and those experimentally infected with larval Schistosoma mansoni trematodes. Infected snails were analysed 8 weeks post-infection. Cohort snails that were left uninfected were analysed at the same time as the infected snails. Sixteen elements (aluminum, boron, barium, calcium, cadmium, copper, iron, potassium, magnesium, manganese, sodium, nickel, lead, selenium, tin and zinc) were found to be present in infected and uninfected whole bodies at concentrations above the detection limit of the ICP-AES analysis. Of these, calcium, cadmium, manganese and sodium were present in significantly higher amounts (Student's t-test, P<0.05) in whole infected versus whole uninfected snails. Variations in the present results compared with other studies reflect intrinsic differences in the larval trematode-snail systems used.

High-performance liquid chromatography (HPLC) was used to determine the effects of a patent Schistosoma mansoni infection on certain carboxylic acids in the digestive gland gonad complex (DGG) and hemolymph of Biomphalaria glabrata. An analysis of DGG samples was done using extraction with 50% Locke's solution, cleanup of the extract by anion exchange solid phase extraction (SPE), and ion exclusion HPLC with ultraviolet detection. Hemolymph was applied directly to the SPE column. Acetic, fumaric, malic, and pyruvic acids were detected, confirmed, and quantified at concentrations ranging from 12 to 280 ppm in the DGG and less than 124 to 8,000 microg/dl in the hemolymph. Infection with S. mansoni caused a significant reduction (Student's t test, P< 0.05) in the concentrations of acetic, fumaric, malic, and pyruvic acids in the DGG but not the hemolymph of B. glabrata compared to uninfected cohort snails. The significant reduction of certain carboxylic acids in the DGG of B. glabrata patently infected with S. mansoni suggests that these acids are utilized by the sporocysts and cercariae in the snail tissue, or that the infection stimulates reduced production or increased utilization by the snail tissue.

The calcium carbonate concentrations in the shells of Helisoma trivolvis and Physa sp. naturally infected with larval trematodes and Biomphalaria glabrata experimentally infected with larval trematodes were analyzed quantitatively. The larval trematode-snail relationships studied were H. trivolvis infected with larval Echinostoma trivolvis and Physa sp. infected with various larval digeneans, and B. glabrata infected with Echinostoma caproni or Schistosoma mansoni. The calcium carbonate concentrations of the shells of infected snails and uninfected cohorts and of the water in which the snails were maintained were determined by ion exchange chromatography. No significant differences in the calcium carbonate concentrations of shells of infected versus uninfected snails were found. The shells of B. glabrata infected with E. caproni contained significantly less calcium carbonate than the shells of uninfected B. glabrata. The hypercalcification hypothesis, i.e., larval trematodes induce an increase in the calcium concentrations in the shells of their snail hosts, was not upheld in any of the snail-larval digenean systems studied herein.

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Tin(II) diphenylcarbazide was recently reported as a sensitive, solid, dry reagent for ozone and nitrogen dioxide (1), the atmospheric oxidants of greatest interest. We now report results obtained with a Perkin-Elmer Model 124 spectro-66506 67401 photometer modified for reflectance measurements.Colorless bis (diphenylcarbazide) tin (II) is stable to oxidation by triplet oxygen when supported on cellulose or starch. On

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Graphite furnace atomic absorption spectrometry and ion chromatography were used to study the metallic ions in the digestive gland-gonad complex (DGG) of Cerithidea californica snails infected with the daughter rediae and cercariae of Euhaplorchis californiensis and in uninfected DGGs. Seven metals (calcium, copper, iron, magnesium, potassium, sodium, zinc) were found to be present in infected and uninfected DGGs at concentrations above the minimum levels required for detection. Of these, calcium was present in significantly higher amounts (Student's t-test, confidence level of 95%) in the infected versus uninfected DGGs; magnesium occurred in significantly lower amounts in the infected DGGs. Our results were compared with a previous study that analyzed metallic ions in the DGG of Helisoma trivolvis naturally infected with Echinostoma trivolvis. That study reported a significant elevation of sodium but a reduction of magnesium and manganese in the DGG of infected snails. Variations in the results of the two studies reflect intrinsic differences in the larval trematode-snail systems used.