Highly read on www.cell.com in September

DNA sequencing is illuminating the genetic underpinnings of 27 rat strains bred to study human diseases.

Since the early 1900s, researchers have selected and bred rats displaying traits such as hypertension and behavioural disorders, producing hundreds of distinct strains. Researchers led by Timothy Aitman at Imperial College London sequenced the complete genomes of several common strains of laboratory rat, revealing more than 13 million genetic variants as well as evidence for the evolutionary pressures behind them. A strain known for its cardiovascular disorders, for example, showed specific selection for gene clusters that are involved in regulating blood pressure and oxidative stress.

Further analysis of how artificial selection created rat models of disease should point to genetic variations and mechanisms that contribute to human maladies.

Cell 154, 691–703 (2013)