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Schistosoma mansoni: quantification of skin penetration and early migration by differential external radioassay and autoradiography

Published online by Cambridge University Press:  06 April 2009

Jay R. Georgi
Jay R. Georgi
Affiliation:
New York State College of Veterinary Medicine, Cornell University, Ithaca, New York 14853
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Summary

Eleven gamma-emitting radionuclides (49Sc, 54Mn, 59Fe ( + 2 and + 3), 60Co, 65Zn, 75Se (as selenomethionine, selenocystine, selenite and selenate), 109Cd, 125Sb, 133Ba, 137Cs and 203Hg) were screened as labelling agents for Schistosoma mansoni cercariae by incubation of infected Biomphalaria glabrata snails in radioactive solution according to the technique of Christensen (1977). Only [75Se]methionine yielded satisfactorily labelled cercariae. Multiple regression analysis of volume, number of cercariae and radioactivity from a series of 10 aliquots of unwashed cercarial suspensions yielded estimates of unbound and cercarial-bound radioactivity that were equivalent or superior to estimates based on assay of washed cercariae and eliminated loss of cercariae. Washing of cercarial suspensions over 8 μm pore diameter Millipore filters was found to result in entanglement of 60–90% of the cercariae on the filter disc. Differential external radioassay, a new technique employing partial body shielding within a total body counter, permitted separate estimation of tail and body radioactivity of conscious mice previously exposed by tail immersion to 75Se-labelled cercariae, with measurements repeated as often as desired. Approximately 39% of the 75Se present in emergent cercariae was retained by schistosomula transformed in vitro but this was subject to considerable variation, especially in schistosomula transformed in vivo. Secreted or catabolized label from penetrant cercariae and schistosomula was rapidly removed from the skin by the bloodstream. Numbers of schistosomula in tail skin were directly proportional to the number of reduced silver foci counted on tail autoradiograms; only a very small fraction of tail radioactivity represented unbound (‘spurious’) label. Migration of schistosomula away from skin was 50% complete at 3·8–4·3 days, as determined by probit analysis of autoradiographic data.

Type
Research Article
Information
Parasitology , Volume 84 , Issue 2 , April 1982 , pp. 263 - 281
Copyright
Copyright © Cambridge University Press 1982

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References

Christensen, N. (1977). A method for the in vivo labeling of Schistosoma mansoni and S. intercalatum cercariae with radioselenium. Zeitschrift für Parasitenkunde 54, 275–88.CrossRefGoogle ScholarPubMed
Christensen, N. O. & Nansen, P. (1979). The preparation and use of radiolabelled parasites and biological substances for studies on host–parasite relationships – with special reference to trematodes. A review. International Atomic Energy Agency, Advisory group meeting, Animal Parasitology.Cambridge,lOth–llth September.Google Scholar
Colley, D. G. & Wikel, S. K. (1974). Schistosoma mansoni: Simplified method for the production of schistosomules. Experimental Parasitology 35, 44–51.CrossRefGoogle ScholarPubMed
de la Cruz, B., Pesigan, T. P., Banzon, T. C., Sevilla, J., Donato, C., Cruz, A. & Castro, V. (1964). A report on the labelling of Schistosoma japonicum cercariae with radioiron. American Journal of Tropical Medicine and Hygiene 13, 545–7.CrossRefGoogle Scholar
Dobinson, A. R., James, E. R. & Christensen, N. O. (1980). Evaluation of L-75Se-methionine as a radioisotopic marker for studying the migration of Schistosoma mansoni schistosomula in mice. International Journal of Nuclear Medicine and Biology 7, 195–6.Google Scholar
Knight, W. B., Liard, F., Ritchie, L. S., Pellegrino, J. & Chiriboga, J. (1968). Labeling of Biomphalariaglabrata and cercariae of Schistosoma mansoni with radioselenium. Experimental Parasitology 22, 309–15.CrossRefGoogle ScholarPubMed
Miller, P. & Wilson, R. A. (1978). Migration of the schistosomula of Schistosoma mansoni from skin to lungs. Parasitology 77, 281–302.Google Scholar
Reed, W. A., Phillips, M. & Roscinski, R. J. (1977). Schistosoma mansoni: Radioisotope uptake and retention by cercariae and developing schistosomules. Experimental Parasitology 42, 331–2.CrossRefGoogle Scholar
Stirewalt, M. A. (1956). Penetration of the host skin by cercariae of Schistosoma mansoni. I. Observed entry into skin of mouse, hamster, rat, monkey and man. Journal of Parasitology 42, 565–80.CrossRefGoogle Scholar