Question

6. You have generated an antisense probe for noggin mRNA. You use this probe to perform in situ hybridization to noggin mRNA in a Xenopus embryo shortly before gastrulation begins.

a) [5pts] What do you see?

b) [5pts] What would the result be if you performed in situ hybridization with this probe using an embryo that had been irradiated at the vegetal pole? Explain your answer.

Answer 1

6. a) The noggin mRNA product is responsible for the dorsal development of the cells in a Xenopus embryo. The in situ hybridization of the generated antisense probe to the mRNA in a Xenopus embryo before gastrulation will stop its expression which will lead to improper development of the dorsal cells. The fate of the dorsal cells in the mesoderm and the neural region is decided by the noggin protein. In its absence the dorsal part will be underdeveloped.

b) The irradiation of the embryo at the vegetal pole leads to the derangement of the cell segregation. The noggin mRNA is only expressed in the dorsal part of the embryo where it decided the fate of the dorsal cells. In the absence of proper segregation/ ventralized embryo, the noggin mRNA might not be expressed.