A new study finds that the more than 90,000 species of mushrooms, molds, yeasts and other fungi found everywhere in the soil, water and air may owe their abilities to grow, spread, and even cause disease to an opportunistic virus they caught more than a billion years ago.

Induced pluripotent stem cells hold promise for regenerative medicine because they can, in theory, turn into any type of tissue and because they are made from a patient's own adult cells, guaranteeing compatibility. However, the technique that turns adult cells into these iPS cells is not foolproof; after reverting to their pluripotent state, these cells don't always correctly differentiate back into adult cells.