Alternative pathway of respiration in Physarum polycephalum plasmodia
Cell Biology International Reports
|January 1, 1985
Abstract:
The external application of inhibitors of glycolysis in the presence of KCN shows a lethal effect on plasmodia of Physarum polycephalum. However, alpha-ketoglutarate, but not succinate, maintains the contraction-relaxation cycle of plasmodial actomyosin in spite of the fact that glycolysis and cytochrome oxidase are inhibited. The oscillations supported by ketoglutarate disappear in the presence of SHAM, an inhibitor of alternative oxidase. These results imply the existence of KCN-resistant, alternative pathway of electron transport in the mitochondria of Physarum polycephalum.
Insights
Inhibiting glycolysis in Physarum polycephalum with KCN is lethal, but alpha-ketoglutarate sustains cellular activity. This suggests a KCN-resistant alternative pathway for electron transport in its mitochondria.
Area of Science:
- Biochemistry
- Cell Biology
- Mycology
Background:
- Physarum polycephalum is a model organism for studying cellular processes.
- Glycolysis and mitochondrial respiration are crucial for cellular energy production.
- Inhibitors like KCN target specific metabolic pathways.
Purpose of the Study:
- To investigate the metabolic pathways supporting Physarum polycephalum plasmodial actomyosin function.
- To determine the role of alternative respiratory pathways in Physarum polycephalum.
- To understand the effects of metabolic inhibition on cellular oscillations.
Main Methods:
- Application of glycolysis inhibitors and KCN to Physarum polycephalum plasmodia.
- Assessment of actomyosin contraction-relaxation cycles.
- Use of alpha-ketoglutarate and succinate as metabolic substrates.
- Inhibition of alternative oxidase with SHAM.
Main Results:
- External application of glycolysis inhibitors with KCN proved lethal to plasmodia.
- Alpha-ketoglutarate, but not succinate, maintained actomyosin cycles despite inhibited glycolysis and cytochrome oxidase.
- Ketoglutarate-supported oscillations were abolished by SHAM, an alternative oxidase inhibitor.
- These findings indicate a KCN-resistant alternative electron transport pathway.
Conclusions:
- Physarum polycephalum possesses a KCN-resistant alternative respiratory pathway.
- This alternative pathway is crucial for maintaining cellular function when glycolysis and cytochrome oxidase are inhibited.
- Alpha-ketoglutarate serves as a substrate for this alternative pathway.
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