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Nylon membrane

Master plate

Grow bacterial colonies
harbouring plasmid Colonies defined by
autoradiography are
used for further analysis

Nylon membrane

with colonies

Nylon membrane mixed

with prehybridisation

buffer in a sealed bag

Prehybridisation solution

replaced with complementary

labelled DNA probe

Nylon membrane

exposed to X-ray film

Wash unbound probe

Autoradiography defines

clones identified by probe

Fig. 6.27Colony hybridisation technique for locating specific bacterial colonies harbouring recombinant

plasmid vectors containing desired DNA fragments. This is achieved by hybridisation to a complementary

labelled DNA probe and autoradiography.

226 Recombinant DNA and genetic analysis