Question

Developmental biology

A mouse contains a mutation that results in a failure of their long
bones to continue growing after embryonic development. The PhrP protein is not
mutated in these mice. Generate a hypothesis that accounts for this phenotype.
Explain why your hypothesis makes sense. Then describe the experiment(s)
necessary to test your hypothesis.

Answer 1

In this the phenotypic change that is observed due to the mutation is that the long bones stop developing or growing beyond the embryonic development.

Hypothesis

The mutation in the genes that synthesize the BMP or bone morphogenetic proteins cause failure of growth of long bones during embryonic development.

The BMP are growth factors which are important and helps in transforming the growth factors of TGFβ family essential for growth of the long bones. They have important role to play during the embryonic development and helps in signal transduction process leading to the cellular process. The Smad 1, 5 and 8 proteins are further activated by the BMP and help in the overall signal transduction process. It was found that when this gene was knocked down, it led to interruption in the signaling cascade and hence leading to the overall deformation.

One experiment that can be done is to genetically knock out the BMP encoding gene which helps in forming the complete signaling pathway and check how exactly has it impacted the development of the bone. There are way by which the gene can be knocked out and the growth can be monitored and tracked by comparing mice which is deficient in BMP factors and one which is able to produce such factors.