Clone Selection
Genomic and cDNA libraries can be probed by hybridization to identify clones.
Heterologous probes (probe from one species used to find a similar gene in another species) can be used between species to identify clones of interest.
Antibodies recognize specific amino acid motifs on the surface of a protein and will bind specifically to these epitopes. If a gene expression vector was used to clone a fragment, antibodies can be used to select colonies or plaques that are expressing the protein. One must use controls to ensure that the antibody does not show signals for the untransformed cells alone. Cloning into the proper reading frame is important to get proper gene expression.
If a simple ligation mix is cloned and transformed or transfected, screening is usually done by selecting several clones and then isolating the DNA from each of them. To identify the clone of interest you would look for a unique restriction enzyme fragment pattern in the clone that is not found in the vector or alternative clones.
One may also use PCR primers sites in the vector flanking the insert to determine the size of the insert.
DNA sequencing may from each end may also confirm the length and sequence of the ends of the clone.
