The role of calcium in the host-parasite relationship of Biomphalaria glabrata/Schistosoma mansoni

Thornhill, Joyce A (1998) The role of calcium in the host-parasite relationship of Biomphalaria glabrata/Schistosoma mansoni. MSc(R) thesis, University of Glasgow.

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Abstract

This study has indicated that parasitised Biomphalaria glabrata snails maintained in a 12 Hour Light (543 Lux) and 12 Hour Dark regime, shed more Schistosoma mansoni cercariae than snails maintained in the dark. Of significance is the observation that the pattern of emergence was similar under both maintenance regimes, suggesting that momentary exposure to only 41Lux light intensity was sufficient to stimulate cercarial shedding. Results also suggested that calcium ion (Ca2+) levels of maintenance water may influence cercarial production. To enable us to compare the calcium content of individual cercariae, a protocol was developed which quantitated the fluorescent emission from the preacetabular glands of cercariae stained with Alizarin Red S, and viewed under the fluorescent microscope. The results suggested that individual cercaria had different amounts of Ca2+ in their preacetabular glands. We made the observation that cercariae lost Ca2+ from their preacetabular glands after a period of incubation at room temperature (21°C). The arbitrary units of fluorescent emission, although allowing relative comparisons between individual cercariae, do not measure total Ca2+ of the cercariae. Consequently further investigations, employing Atomic absorption and Plasma emission spectrometry, determined the total calcium content of both cercariae and shedding water. These results confirmed that aging cercariae lost Ca2+ and that the incubation water gained Ca2+ during the period. Shedding snails also lost Ca2+ during a 2 hour shedding period. To investigate whether Ca2+ levels affected surface properties of the cercariae, we incubated cercariae with EGTA, and labelled with PKH26. We found that incubation of cercariae in 20mM EGTA prevented tail loss and inhibited membrane damage. Incubating cercariae with the fluorescent PKH26 lipid label clearly highlighted the nervous system of both cercarial body and tail. The possible effect of calcium loss, by aging cercariae, on successful parasite penetration and maturation is discussed at length in the context of current knowledge.

Item Type: Thesis (MSc(R))
Qualification Level: Masters
Additional Information: Adviser: John Kusel
Keywords: Parasitology
Date of Award: 1998
Depositing User: Enlighten Team
Unique ID: glathesis:1998-71565
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 10 May 2019 14:16
Last Modified: 10 May 2019 14:16
URI: http://theses.gla.ac.uk/id/eprint/71565

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