Today@Dal

What separates animals, plants, fungi and even amoebas from bacteria? Well, there's one feature that no longer universally makes us distinct, thanks to a new study that redefines what it means to belong to our limb on the tree of life.

That limb includes all eukaryotes, multi-celled organisms and more complex single-celled organisms with cells that contain specialized mini-organs called organelles.

Organelles include the nucleus, which holds most of the cell's DNA and mitochondria, a "powerhouse" that uses oxygen to produce energy – things that bacteria and archaea from the two other "domains," or limbs, on the tree of life don't have.

But now, for the first time, scientists have discovered a eukaryote with no mitochondria – forcing them to reconsider what it means to be a eukaryote.

"In my view this is an important finding because it changes our concept of what minimally defines a eukaryotic cell," said Andrew Roger, a Dalhousie University researcher who co-authored the study published in the journal Current Biology.

"Until now, all eukaryotes known had some form of mitochondria in their cells and so mitochondria were considered to be fundamental components of eukaryote cell biology."

The mitochondria-less organism, called Monocercomonoides, lives inside the gut of a chinchilla, a rodent from the Andes mountains of South America known for its luxurious fur.

Read more (http://www.cbc.ca/news/technology/mitochondria-eukaryote-1.3579238)