Question

Decribe insertional activation with the help of blue white screening .why is it so called

Answer 1

We inserted GFP-gene into plasmid Bluescript SK+, transformed E. coli with this construct, and then plated on an agar plate with Ampicillin and X-gal to do a blue/white screening. We got blue colonies and white colonies, and normally the white colonies are considered positive for the insert and the blue ones are negative for the insert. The problem is that the results we got are actually the opposite. If we look at the plate under UV-light, we see that ALL the blue colonies are fluorescent, which means they actually produce the GFP, and ALL the white ones are not!! How would you explain this?? Thank you



i thought that maybe the insert could be in frame with lacz', so we get fusion proteins. However this doesn't explain why we got white colonies which are not fluorescent