In your colony, you find a mutant platypus which suffers from uncoordinated move
ID: 272125 • Letter: I
Question
In your colony, you find a mutant platypus which suffers from uncoordinated movement. You map the mutation to a membrane protein, and immunohistochemistry shows that the protein is transiently expressed in the axon growth cones of cortical motor neurons. suggesting a connectivity defect. Propose an experiment to determine the target spinal neurons that the cortical neurons are connected to, to determine if the connectivity of the cortical motor neurons is similar in wildtype and mutant platypus.
The question is asked based on the following article:
"Deleted in Colorectal Cancer (DCC) Encodes a Netrin Receptor"
Explanation / Answer
Ans: Platypus which suffers from uncoordinated movement having a mutation in neuronal development especially in the axon growth cones of cortical motor neurons
Netrins are chemoattractants for commissural axons in the vertebrate spinal cord. Deleted in Colorectal Cancer (DCC), a transmembrane protein of the immunoglobulin superfamily, is expressed on spinal commissural axons and possesses netrin-1-binding activity. antibody to DCC selectively blocks the netrin-1-dependent outgrowth of commissural axons and prevents effective growth of the or branching of the cortical motor neurons
Immunohistochemistry experiment can be carried out to determine difference bwtween wildtype and mutant to see the connectivity of the cortical motor neurons. Axon growth cone of muscle area samples can be collected, from both normal and mutated patypus, make thin sections using cryostat and Immunostained with anti DCC antibody. If anti DCC antibody binds with tissue sections shows the presence of mutation. In normal platypus this binding should be negative. Based on the immunofluroscence of the bound antibody we can differentiate the motor neuron connecting pattern difference between mutant and wildtype platipus.
PCR experiments can be carried out to see the DCC expression levels. Design a primer and prepare Cdna by rtPCR, sequnce the Cdna and blast with the Platypus geneome. Mutations can be ascertained in the mutant platypus.