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Membrane internalization processes in different stages of Schistosoma mansoni as shown by a styryl dye (Frei Mao
F Ribeiro1, P M Coelho, L Q Vieira
1Department of Biochemistry and Molecular Biology, Glasgow University. gbca66@ucdf.gla.ac.uk
Abstract:
We have used a styryl dye FM 1-43 that cannot cross membranes passively to evaluate membrane vesicle internalization processes from the heptalaminate surface membrane in schistosomula and adult Schistosoma mansoni. The process of dye internalization was faster in adult worms than in 3 h skin or 24-h-old mechanically transformed schistosomula. Dye internalization and vesicle formation were inhibited at low temperature which suggests that the process is energy dependent. Dye internalization was observed to be a result of vesicle formation. This process is impaired by primaquine independently of the parasite stage. The specific Ca2+ chelator EGTA affected dye internalization at a concentration of 5 mM. When parasites were labelled in the presence of genistein (a tyrosine kinase inhibitor) uptake of the dye was blocked in 24-h-old schistosomula. However, only a partial blockage of the dye internalization was seen in adult worms. These results suggest that dye internalization mediated by tyrosine kinase signalling is developmentally regulated.
Insights
Schistosoma mansoni parasites internalize membrane vesicles via an energy-dependent, primaquine-sensitive process. This tyrosine kinase-mediated dye uptake is developmentally regulated, occurring faster in adult worms than schistosomula.
Area of Science:
- Parasitology
- Cell Biology
- Biochemistry
Background:
- Schistosoma mansoni causes schistosomiasis, a major human helminthic disease.
- Understanding parasite membrane dynamics is crucial for developing new treatments.
- The heptalaminate surface membrane plays a key role in parasite-host interactions.
Purpose of the Study:
- To investigate membrane vesicle internalization in Schistosoma mansoni.
- To characterize the energy dependence and regulation of this process.
- To identify molecular pathways involved in dye uptake.
Main Methods:
- Utilized the membrane-impermeant styryl dye FM 1-43.
- Assessed dye internalization in schistosomula and adult worms.
- Investigated effects of temperature, primaquine, EGTA, and genistein.
Main Results:
- Dye internalization, a vesicle formation process, was faster in adult worms than schistosomula.
- The process is energy-dependent and inhibited by low temperatures.
- Primaquine impaired internalization independently of parasite stage.
- Tyrosine kinase inhibition by genistein blocked uptake in schistosomula but only partially in adults.
Conclusions:
- Membrane vesicle internalization in Schistosoma mansoni is an active, energy-dependent process.
- Tyrosine kinase signaling mediates dye uptake in a developmentally regulated manner.
- Primaquine affects internalization across parasite stages, suggesting therapeutic potential.