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Published on: April 7, 2018
Changes in mitochondrial electron transport chain activity during insect metamorphosis
1Department of Biological Sciences, Ohio University, Athens, OH 45701, USA. chamberl@ohio.edu
Summary
During tobacco hornworm metamorphosis, mitochondrial respiration declines due to targeted inactivation of specific respiratory chain sites, particularly complexes II and IV (cytochrome c oxidase). This targeted destruction explains the loss of midgut function during this developmental transition.
Area of Science:
- Biochemistry
- Developmental Biology
- Insect Physiology
Background:
- The midgut of Manduca sexta undergoes programmed cell death during metamorphosis.
- Mitochondrial oxygen consumption decreases post-commitment to pupation.
Purpose of the Study:
- To investigate the role of the electron transport chain in the decline of mitochondrial function during Manduca sexta metamorphosis.
- To determine if specific respiratory complexes are affected during this process.
Main Methods:
- Measurement of maximal activities of respiratory chain complexes I-IV in isolated midgut mitochondria.
- Analysis of cytochrome c oxidase (COX) turnover number in isolated mitochondria and in organello.
- Assessment of endogenous cytochrome c levels.
Main Results:
- Activities of complexes II and IV (cytochrome c oxidase) were significantly higher in precommitment than postcommitment larvae.
- No significant changes were observed in the activities of complexes I and III.
- COX turnover number and in organello COX activity decreased in postcommitment larvae, potentially due to loss of cytochrome c.
Conclusions:
- The decline in mitochondrial respiration during Manduca sexta metamorphosis is caused by targeted inactivation or destruction of specific respiratory chain components, not general organelle degradation.
- Changes in COX enzyme structure, lipid environment, or loss of cytochrome c contribute to reduced mitochondrial function.
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