Sonya Williams willis03 at MCHIP00.MED.NYU.EDU
Fri Apr 25 09:26:50 EST 1997

I can explain you XL-1 Blue woes.

A possible explanation.

the plasmid gets chewed up on both ends before you ligate it. (do the
controls with out ligating insert, you get incomplete Lacz expression.)
this means that your insert gets in, but some of your restriction sites are
gone because the plasmid is smaller. 1. Use sites further out (HindIII Xba
instead of EcoRI), 2.  Order new plasmid.

Use a southern blot, and proper gel markers to check the size of your
plasmid (should be 3,9) and digest plasmid with no insert! from a dark blue


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