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Schistosoma mansoni: a comparative study on two cercarial transformation methods
N A Hammouda1, I F Abou el Naga, M M el Temsahi
1Department of Parasitology, Faculty of Medicine, Alexandria University, Egypt.
Journal of the Egyptian Society of Parasitology
|December 1, 1994
Summary
Researchers developed an in vitro method to study Schistosoma mansoni cercariae transformation using linoleate. Optimal linoleate concentration (3 mM) maximized transformation (90%) and showed higher proteolytic activity compared to mechanical methods.
Area of Science:
- Parasitology
- Infectious Diseases
- Biochemistry
Background:
- Schistosoma mansoni cercariae require specific conditions for transformation into schistosomulae.
- Understanding cercarial penetration and transformation is crucial for developing anti-schistosomiasis strategies.
- Previous methods for studying transformation were limited.
Purpose of the Study:
- To develop and validate an in vitro agar:gelatin plate method for measuring Schistosoma mansoni cercarial penetration and transformation.
- To determine the optimal concentration of linoleate for inducing cercarial transformation.
- To compare the biochemical and cellular changes during linoleate-induced transformation versus mechanical transformation.
Main Methods:
- An agar:gelatin plate assay was designed to test varying concentrations of linoleate.
- Schistosoma mansoni cercariae were exposed to a range of linoleate concentrations to assess penetration and transformation rates.
- Proteolytic activity and nuclear content were measured and compared between linoleate-induced and mechanical transformation methods.
Main Results:
- Cercarial penetration increased with linoleate concentration, reaching nearly 100% at 0.3 mM and above.
- Cercarial transformation showed a narrower optimal range, with maximum transformation (90%) occurring at 3 mM linoleate.
- Linoleate-induced transformation exhibited higher proteolytic activity than mechanical transformation, though both methods reduced nuclear content.
Conclusions:
- The agar:gelatin plate method effectively quantifies Schistosoma mansoni cercarial penetration and linoleate-induced transformation in vitro.
- A 3 mM linoleate concentration is optimal for maximizing cercarial transformation, indicating a key role for linoleate in this process.
- Linoleate-induced transformation is biochemically distinct, with higher proteolytic activity, suggesting a more natural transformation pathway.