Developmental expression of nuclear genes that encode mitochondrial proteins: insect cytochromes c

Area of Science:

• Molecular Biology
• Developmental Biology
• Biochemistry

Background:

• Mitochondrial biogenesis is crucial for cellular energy production.
• Tissue-specific regulation of mitochondrial genes is not fully understood.
• Cytochrome c plays a vital role in the electron transport chain.

Purpose of the Study:

• To investigate the developmental regulation of mitochondrial biogenesis.
• To study the expression of the Manduca sexta thoracic muscle cytochrome c gene.
• To isolate the corresponding gene in Drosophila melanogaster.

Main Methods:

• Studied gene expression during adult eclosion in Manduca sexta.
• Utilized cDNA cloning and blot hybridization analysis.
• Employed polysome immunoadsorption and hybrid selection/translation screening.

Main Results:

• Thoracic muscle cytochrome c mRNA levels increase transcriptionally during development.
• Holoprotein levels increase 40-fold per insect thorax prior to emergence.
• Cytochrome c mRNA levels peak at 0.04% of total poly(A)+ RNA.
• Cytochrome c levels remain proportional to other respiratory chain components.

Conclusions:

• Mitochondrial biogenesis is primarily regulated at the transcriptional level.
• Coordinated developmental programs govern respiratory chain component expression.
• The study provides a cDNA clone for isolating homologous genes in other species.