Single gene controls fish brain size and intelligence

A single gene called Angiopoietin-1 ( Ang-1 ) drives brain size and intelligence in fish according to a new study by researchers at UCL, Stockholm University and University of Helsinki. Fish with larger brains and higher intelligence had higher expression of Ang-1 , and when expression levels of Ang-1 were experimentally reduced, brains shrunk. These trends were seen in two unrelated species of fish - guppies (Poecilia reticulata) and zebra fish ( Danio rerio ) - indicating expression of Ang-1 is important for brain growth and development in fish generally. The study, published today in Proceedings of the Royal Society B , identified the underlying genetics of natural variation in brain size and cognitive abilities in fish. Ang-1 could play an important role in the brain development of other vertebrates, including humans, but future research is required to establish this say the scientists involved. Populations of guppies selected for either large or small brains, with associated differences in intelligence, were used for the first step in the study which was a complete genome analysis of differently expressed genes. There was a 10% difference in brain size between the large and small-brain guppies and from the genetic analysis, Ang-1 was identified as the only gene expressed at different levels in each replicate population.