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Fasciola hepatica miracidia are dependent on respiration and endogenous glycogen degradation for their energy generation

Published online by Cambridge University Press:  21 May 2002

H. BOYUNAGA
Affiliation:
Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Utrecht University, P.O. Box 80176, 3508 TD Utrecht, The Netherlands Present address: Department of Biochemistry, Faculty of Medicine, Kirikkale University, Turkey.
M.G.J. SCHMITZ
Affiliation:
Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Utrecht University, P.O. Box 80176, 3508 TD Utrecht, The Netherlands
J.F.H.M. BROUWERS
Affiliation:
Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Utrecht University, P.O. Box 80176, 3508 TD Utrecht, The Netherlands
J.J. VAN HELLEMOND
Affiliation:
Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Utrecht University, P.O. Box 80176, 3508 TD Utrecht, The Netherlands
A.G.M. TIELENS
Affiliation:
Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Utrecht University, P.O. Box 80176, 3508 TD Utrecht, The Netherlands

Abstract

It is generally accepted that free-living stages of parasitic helminths are dependent on aerobic degradation of endogenous energy sources for their energy generation. This concept, however, is not the result of extensive experimental evidence, but originated mainly intuitively as oxygen is widely available in their habitat and these stages generally have a small size. Schistosoma mansoni, the sole parasitic helminth whose energy metabolism has been studied throughout its life-cycle indeed has aerobically functioning free-living stages. However, large differences exist in energy metabolism between adult stages of distinct parasitic helminths, and caution should be taken in predicting that all free-living stages of all parasitic helminths have the same, aerobic energy metabolism. Hence, this report studied the energy metabolism of Fasciola hepatica miracidia and demonstrated that F. hepatica miracidia are also dependent on aerobic degradation of their endogenous glycogen stores by glycolysis and on Krebs cycle activity for energy generation. However, in contrast to S. mansoni, F. hepatica miracidia cannot function anaerobically, as inhibition of the respiratory chain blocked motility and carbohydrate degradation, and finally resulted in death of the miracidia. Therefore, this report demonstrated that differences exist between miracidia of distinct species, in pre-adaptation of their energy metabolism to the occasional hypoxic conditions within their next host.

Type
Research Article
Copyright
© 2001 Cambridge University Press

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