The Hoxd9–13 genes are thought to specify digit identity (see Fig...

Question

The Hoxd9–13 genes are thought to specify digit identity (see Figure 18.18).

What would be the consequence of ectopically expressing Hoxd10 throughout the developing mouse limb bud? What about Hoxd11? What about both Hoxd10 and Hoxd11?

Accepted Answer

Hey, everyone. Let's take a look at this question together which protein mutation is likely to be associated with three axial polydactyly. A condition characterized by the formation of an extra digit attached to the thumb. Is it answer choice. A Indian hedgehog protein. Answer choice B Sonic Hedgehog protein, answer choice C hedgehog interacting protein or answer choice D desert hedgehog protein. Let's work this problem out together to try to figure out which protein mutation is likely to be associated with preaxial polydactyly. So when it comes to the formation of digits in the thumb, we know that we have something called the zone of polarizing activity or the ZP A for short. And the zone of polarizing activity is found on the posterior side of the limb bud and it acts as the organizer to promote digit formation. And in this case, we're talking about the digits attached to the thumb. And in order for the zone of polarizing activity to promote that digit formation, the ZP A secretes the sonic hedgehog protein, which is a signaling protein that is involved in the regulation of limb patterning. And so the sonic hedgehog protein is responsible for the normal anterior posterior patterning of the developing limb. So, if we have a mutation in that protein, which is that sonic hedgehog protein, we could end up with that extra digit that is attached to the thumb. And so that means that a protein mutation likely associated with preaxial polydactyly is sonic hedgehog protein, which is answer choice be the correct answer. Since that sonic hedgehog protein is the signaling protein involved in the regulation of the limb patterning. And a protein mutation in that Sonic hedgehog protein could lead to the extra digit attached to the thumb because the mutation could disrupt the normal anterior posterior patterning of that developing limb leading to preaxial polydactyly. I hope you found this video to be helpful. Thank you and goodbye.

The Hoxd9–13 genes are thought to specify digit identity (see Figure 18.18). What would be the consequence of ectopically expressing Hoxd10 throughout the developing mouse limb bud? What about Hoxd11? What about both Hoxd10 and Hoxd11?

Key Concepts

Hox Genes

Ectopic Expression

Digit Identity

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