Mitochondria (singular: mitochondrion) are present in all animal and plant cells from the microscopic worm-like Caenorhabditis elegans to towering eucalypt trees. But what are they, and why are they important? 

Mitochondria are almost like miniature cells within our own cells. Around a billion years ago, before complex creatures like ourselves existed, our antecedents' cells engulfed smaller cells, and through time and evolution formed an intimate symbiotic relationship. Mitochondria became specialised in generating energy for their host by burning the carbohydrates with the oxygen it breathes. 

In each of our muscle cells and neurons, we have hundreds of mitochondria, and each of those contain their own DNA genome, separate to our more familiar nuclear genome. 

The mitochondrial genome, a trace of the mitochondria's ancient origin, is to this day critical to our health. Rare mitochondrial genome mutations may disrupt mitochondrial energy production, which can have devastating consequences on our bodies. We now suspect that many common age-related degenerative disorders such as Alzheimer’s and Parkinson’s diseases are due to in part to the accumulation of mutations in our mitochondrial genome over our lifetime. 

Researchers at QBI are looking for ways in which our cells can counteract damage to the mitochondrial genome using C. elegans, that like humans have mitochondria. Specialised genetic tools are being used to invoke DNA damage to the mitochondrial genome, and then genetic mutants are being isolated that can suppress the effects of the mitochondrial damage. 

Studying mitochondrial damage in C. elegans is powerful, as it is allows thousands of genes to be screened simultaneously. Already 17 mutations that undermine the effects of mitochondrial genome damage have been isolated, and are currently being investigated to determine whether they can help improve mitochondrial genome damage in humans, and ultimately treat mitochondrial and degenerative diseases. Importantly, we wouldn't be able to discover these genes without using the simple organism C. elegans, as these genetic screens cannot be performed in humans or other mammals.