Skip to main content
×
Home
    • Aa
    • Aa

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.

Copyright
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.
Footnotes
Hide All

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.

Footnotes
Linked references
Hide All

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.

Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Parasitology
  • ISSN: 0031-1820
  • EISSN: 1469-8161
  • URL: /core/journals/parasitology
Please enter your name
Please enter a valid email address
Who would you like to send this to? *
×