Investigating Actin and Mitochondria Dynamics
Two major differences separate the mitochondrion from most other organelles. First, it has its own circular DNA. Secondly, it reproduces independently of the cell in which it is found; an apparent case of endosymbiosis. Scientists hypothesize the origins of this circumstance go back millions of years to a time when small, free-living prokaryotes were engulfed, but not consumed, by larger prokaryotes, perhaps because they did not submit to the digestive enzymes of the host organism. The two organisms developed a symbiotic relationship over time, the larger organism providing the smaller with ample nutrients and the smaller organism providing ATP molecules to the larger one. Eventually, according to this view, the larger organism developed into the eukaryotic cell and the smaller organism into the mitochondrion. In the digital videos presented above, normal Gray fox lung fibroblast cells (FoLu line) are expressing mKusabira Orange fluorescent protein (mKO) fused to the mitochondrial targeting signal from subunit VIII of human cytochrome C oxidase, as well as mCherry fluorescent protein fused to human beta-actin.