Mitochondrion: Cell stars?

"A star collapses when the fuel is used up and the energy flow from the core of the star stops. Nuclear reactions outside the core cause the dying star to expand outward in the "red giant" phase before it begins its inevitable collapse." -NASA

I first heard of this from Dr. Jack Kruse and how this phenomenon is also seen in the mitochondria of cells. #bluelighthazard

When mitochondria are stressed (specifically from energy deficiency) they elongate through a process know mitochondrial hyper-fusion creating a generation of massively enlarged mitochondria.

During this process two distinct #mitochondria fuse and work together sharing resources in attempt to maintain cellular energy levels and homeostasis. (Rolland et al., 2013; Friedman and Nunnari, 2014).

Mitochondrial fusion elevates cristae density (per micron) inside the mitochondria and since the cristae houses the electron transport chain an increase in its density results in increased metabolic efficacy (elevated cellular respiration)

Researchers identify higher mitochondrial cristae density in endurance‐trained athletes (+23%) compared to non‐athletes. (Cameron F. Leveille, John S. Mikhaeil 2017)

Mitochondrial cristae density is a better predictor of maximal #oxygen uptake than mitochondrial volume. Nielsen et al. 2017)

Side note: #photobiomodulation increased the relative surface area of mitochondrial cristae by 25% in fungi.

Apart from maintaining energy, the fusion and elongation allows mitochondria to evade #autophagy as autophagosomes at times fail to engulf such enlarged #mitochondrion.

The evasion is likely an evolutionary adaptation that buys time until homestasis is restored. (Rambold et al., 2011).