Monday, December 10, 2012

How Fins Became Limbs

Recent research suggests that hands and feet evolved from fins due to gains in DNA components that activate certain genes.

Researches added extra Hoxd13, a gene known to affect the forming of body parts, to the fin of a zebrafish embryo. The experimental embryo developed more cartilage and had reduced fin cartilage. This is consistent with the formation process of human limbs. As a result, the zebrafish developed one limb that appeared more like a leg than a fin.

After they confirmed that Hoxd13 is essential to limb development, the researches guessed that evolutions in control elements were responsible for increased expression of that gene. They introduced a Hoxd13 control element that is present in mice to the zebrafish. As they suspected, the control element had the ability to drive gene expression in mice.

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