Different location-dependent 'on-switches' control a gene important for both limb and skull formation
Growing a baby is a difficult business. Thousands of genes must be switched on in carefully controlled patterns to create head, shoulders, knees, toes and everything else in between. Intriguingly, many genes are used in several different places in the developing foetus, controlled by banks of ‘switches’ (known as enhancers) that turn each gene on at the right time and in the right place. These images show the bones in the feet of two mice – the one on the left is healthy but the animal on the right has a fault in the control switch activating a gene called Twist1 in the developing limbs, while a different set of switches turn it on in the skull and face. Problems with TWIST1 in humans lead to serious problems with skull and limb formation, so finding the location of these switches is bringing important new insights into what might be going wrong.
Written by Kat Arney
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