What's on the Inside

Bala at Bitesize Bio posts a protocol that is even faster than colony PCR to detect cloned inserts. This "quick and dirty" method, called colony cracking, begins by lysing a colony and running the extract on a gel. The clones are then identified based on their mobility. Plasmids with inserts, being bigger, will travel more slowly than plasmids without them. "Obviously, the larger the insert, the easier it will be to distinguish between positive and negative clones, but researchers claim to be able to detect inserts of only 200bp," writes Bala.