Are size and mitochondrial power of cells inter-determined?

Mitochondria are the central hub of ATP production in most eukaryotic cells. Cellular power (energy per unit time), which is primarily generated in these organelles, is crucial to our understanding of cell function in health and disease. We investigated the relation between a mitochondrion's power (metabolic rate) and host cell size by combining metabolic theory with the analysis of two recent databases, one covering 109 protists and the other 63 species including protists, metazoans, microalgae, and vascular plants. We uncovered an interesting statistical regularity: in well-fed protists, relatively elevated values of mitochondrion power cluster around the smallest cell sizes and the medium-large cell sizes. In contrast, in starved protists and metazoans, the relation between mitochondrion power and cell size is inconclusive, and in microalgae and plants, mitochondrion power seems to increase from smaller cells to larger ones (where this investigation includes plant cells of volume up to ca. 2.18 x 105 & mu;m3). Using these results, estimates are provided of the number of active ATP synthase molecules and basal uncouplers.

Automated summary

Mitochondria play a central role in ATP production in eukaryotic cells. To understand the relationship between a mitochondrion's power and host cell size, researchers analyzed two databases and found that in well-fed protists, higher values of mitochondrion power cluster around both the smallest and medium-large cell sizes. However, the relation between mitochondrion power and cell size is inconclusive in starved protists and metazoans, while in microalgae and plants, mitochondrion power seems to increase from smaller to larger cells. This study provides estimates of the number of active ATP synthase molecules and basal uncouplers.