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Ca2+ transport in digitonin-permeabilized trypanosomatids
A E Vercesi1, D V Macedo, S A Lima
1Departamento de Bioquimica, Instituto de Biologia, UNICAMP, Campinas, S.P., Brazil.
Molecular and Biochemical Parasitology
|August 1, 1990
Summary
This study reveals that mitochondria in trypanosomatids like Leishmania can transport and retain calcium ions (Ca2+). Different species show varying Ca2+ retention capabilities, impacting cellular calcium homeostasis.
Area of Science:
- Biochemistry
- Cell Biology
- Parasitology
Background:
- Trypanosomatids possess complex calcium ion (Ca2+) transport systems.
- Understanding Ca2+ transport is crucial for cellular function and parasite viability.
Purpose of the Study:
- To investigate the in situ Ca2+ transport mechanisms in Leishmania and Crithidia mitochondria.
- To characterize the properties of mitochondrial Ca2+ uptake and retention in these parasites.
Main Methods:
- Digitonin was used to permeabilize plasma membranes for studying intracellular transport.
- Tetraphenylphosphonium-sensitive electrodes monitored mitochondrial membrane potential.
- Inhibitors like ruthenium red and carbonyl cyanide p-trifluoromethoxyphenylhydrazone were used to probe Ca2+ transport pathways.
Main Results:
- Mitochondria in Leishmania and Crithidia build up and retain membrane potential.
- Ca2+ uptake led to mitochondrial depolarization, indicating an electrogenic transport mechanism.
- Inorganic phosphate stimulated Ca2+ uptake, while ruthenium red and CCCP partially and fully inhibited it, respectively.
- Crithidia fasciculata mitochondria retained Ca2+ effectively, unlike Leishmania species.
- A vanadate-sensitive Ca2+-transporting system was also identified.
Conclusions:
- Mitochondria play a significant role in Ca2+ homeostasis in trypanosomatids.
- Species-specific differences in Ca2+ retention exist, with implications for parasite biology.
- Both mitochondrial and plasma membrane-associated Ca2+ transport systems are present in these organisms.