Official websites use. Share sensitive information only on official, secure websites. Conceptualization: D. Methodology: D. Visualization: D. Funding acquisition: N. Supervision: R. Writing β original draft: D. Writing β final draft: all authors. Corresponding author Dillon J. Mitochondrial adaptations are fundamental to differentiated function and energetic homeostasis in mammalian cells.
But the mechanisms that underlie these relationships remain poorly understood. Here, we investigated organ-specific mitochondrial morphology, connectivity and protein composition in a model of extreme mammalian metabolism, the least shrew Cryptotis parva.
This was achieved through a combination of high-resolution 3D focused ion beam electron microscopy imaging and tandem mass tag mass spectrometry proteomics. We demonstrate that liver and kidney mitochondrial content are equivalent to the heart, permitting assessment of mitochondrial adaptations in different organs with similar metabolic demand. Muscle mitochondrial networks cardiac and skeletal are extensive, with a high incidence of nanotunnels β which collectively support the metabolism of large muscle cells.
Mitochondrial networks were not detected in the liver and kidney as individual mitochondria are localized with sites of ATP consumption. This configuration is not observed in striated muscle, likely due to a homogeneous ATPase distribution and the structural requirements of contraction. These results demonstrate distinct, fundamental mitochondrial structural adaptations for similar metabolic demand that are dependent on the topology of energy utilization process in a mammalian model of extreme metabolism.
Keywords: allometry, inter-organelle interactions, metabolism, mitochondria, reticulum. This study investigates the role of mitochondrial morphology and protein composition in setting the extreme metabolic rates of one of the smallest extant mammals, the North American least shrew Cryptotis parva. To do this, mitochondrial characteristics from liver, kidney, skeletal muscle and heart tissues were compared as these tissues are major contributors to basal and maximum metabolic states.
