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    This article has been cited by the following publications. This list is generated based on data provided by CrossRef.

    Mikeš, Libor Zìdková, Lenka Kašný, Martin Dvořák, Jan and Horák, Petr 2005. In vitro stimulation of penetration gland emptying by Trichobilharzia szidati and T. regenti (Schistosomatidae) cercariae. Quantitative collection and partial characterization of the products. Parasitology Research, Vol. 96, Issue. 4, p. 230.


    Haas, W. 1994. Physiological analyses of host-finding behaviour in trematode cercariae: adaptations for transmission success. Parasitology, Vol. 109, Issue. S1, p. S15.


    Granzer, Monika and Haas, Wilfried 1986. The chemical stimuli of human skin surface for the attachment response of Schistosoma mansoni cercariae. International Journal for Parasitology, Vol. 16, Issue. 6, p. 575.


    Linder, E. 1986. Fluorochrome-labelled lectins reveal secreted glycoconjugates of schistosome larvae. Parasitology Today, Vol. 2, Issue. 8, p. 219.


    Coles, G. C. 1984. Recent advances in schistosome biochemistry. Parasitology, Vol. 89, Issue. 03, p. 603.


    Pinto, A.Ventura Pinto, M.do C.Ribeiro Gilbert, Benjamin Pellegrino, J. and Mello, Romulo T. 1977. Schistosomiasis mansoni: blockage of cercarial skin penetration by chemical agents: I. naphthoquinones and derivatives. Transactions of the Royal Society of Tropical Medicine and Hygiene, Vol. 71, Issue. 2, p. 133.


    Eveland, L. K. and Morse, S. I. 1975. Schistosoma mansoni: in vitro conversion of cercariae to schistosomula. Parasitology, Vol. 71, Issue. 02, p. 327.


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Further studies of Schistosoma mansoni cercarial stimulation by crude egg lecithin and other lipids*

Abstract

The stimulus provided to cercariae by the skin fat of their definitive hosts is not the same for Schistosoma mansoni and Austrobilharzia terrigalensis. Cercariae of the former parasite are stimulated by unsaturated fatty acids, those of the latter by cholesterol.

A reinvestigation of the penetration stimulant factors present in crude egg lecithin, which contains both cholesterol and free fatty acids as impurities, has shown that the latter are responsible for the stimulus in S. mansoni. The phospholipid fraction is inactive as is pure cholesterol. A little excitation of cercariae is produced by the monoglyceride fraction. These results fully confirm earlier findings.

Of surface active agents other than lecithin, stimulatory activity was found only in one product which possessed carboxyl groups. Of the C18 acids examined, stearic (18:0) is inactive, oleic (18:1) slightly active, linoleic (18:2) and linolenic (18:3) acids highly active. Oleic acid was shown by GC-mass spectrometry to be the most abundant acid in crude egg lecithin and is probably the main penetration stimulus present.

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Corresponding author
Naval Medical Research Institute, Bethesda, Maryland 20014. Current address of F.A.: New York State Veterinary College, Cornell University, Ithaca, New York 14850.
Instituto de Pesquisas da Marinha, Rua Ipiru, s/n°, Ilha do Governador, Rio de Janeiro ZC32, Brazil.
§Arthritis Metabolic and Digestive Diseases Institute, National Institutes of Health, Bethesda, Maryland 20014.
Biomedical Research Institute, American Foundation for Biological Research, 12111 Parklawn Drive, Rockville, Maryland 20852. Requests for reprints should be sent to M. Stirewalt.
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The opinions and assertions contained herein are those of the authors and are not to be construed as official or reflecting the views of the Navy Department or the Naval service at large.

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This list contains references from the content that can be linked to their source. For a full set of references and notes please see the PDF or HTML where available.

F. G. Austin , M. A. Stirewalt & R. Danziger (1972). Schistosoma mansoni: stimula tory effect of rat skin lipid fractions on cercarial penetration behaviour. Experimental Parasitology 31, 217–24.

M. L. Blank , L. J. Nutter & O. S. Privett (1966). Determination of the structure of lecithins. Lipids 1, 132–5.

A. J. MacInnis (1969). Identification of chemicals triggering cercarial penetration responses of Schistosoma mansoni. Nature, London224, 1221–2.

C. J. Shiff , S. H. W. Cmelik , H. E. Ley & R. L. Kriel (1972). The influence of human skin lipids on cercarial penetration responses of Schistosoma haematobium and Schistosoma mansoni. Journal of Parasitology 58, 476–80.

M. A. Stirewalt (1963). Cercaria vs Schistosomule (Schistosoma mansoni): absence of the pericarial envelope in vivo and the early physiological and histological metamorphosis of the parasite. Experimental Parasitology 13, 395406.

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Parasitology
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