CRG: Key genetic event underlying fin-to-limb evolution

CRG: Key genetic event underlying fin-to-limb evolution

News from CRG

A study of catsharks reveals how alterations in the expression and function of certain genes in limb buds underlie the evolution of fish fins to limbs. The findings are reported by researchers from Tokyo Institute of Technology (Tokyo Tech), the Centre for Genomic Regulation (CRG, Barcelona) and their collaborators in the journal eLife and give new insight into how fish evolved to live on land in the form of early tetrapods.

The first four-legged, land-living creatures – known as early tetrapods – evolved from fish, following the transformation of fins into limbs. This fin-to-limb evolution is a crucial, yet so far unsolved, example of how morphological changes can dramatically alter life on Earth. Now, researchers at Tokyo Tech and CRG, together with scientists across Japan and Spain, have revealed how genetic alterations governing the patterning of skeletal structures in fins may have led to the evolution of limbs and the rise of early tetrapods.

To determine whether shifts in the balance of anterior and posterior field occurred during fin-to-limb evolution, Onimaru, postdoctoral researcher currently at Sharpe's lab (CRG), and his colleagues carefully compared the expression, function and regulation of genes involved in anterior-posterior patterning in pectoral fins of catsharks, with those of mice. They found that, in pectoral fin of catshark embryos, Gli3 expression was intensified posteriorly, and the balance of the anterior and posterior fields was shifted. This indicates that a major genetic shift (posteriorisation) occurred as tetrapods evolved.

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Onimaru K1, Kuraku S2, Takagi W3, Hyodo S3, Sharpe J4, Tanaka M1. A shift in anterior-posterior positional information underlies the fin-to-limb evolution. Elife. 2015 Aug 18;4. doi: 10.7554/eLife.07048.