How should DNAs be prepared for injection?

We find that the DNA preparation step is very important for successful transgenesis. We recommend using either the Qiagen or Invitrogen Midi-prep kits for DNA preparation. In no case should Mini-prep DNA be sent to us as this is toxic to embryos. All DNA samples should be provided in EB (10 mM Tris-Cl, pH 8.5) or water at 500 ng/μl. We request that you send us 20 µl of such DNA. For larger constructs (>25 kb), 40 µl of 500 ng/µl DNA is required. To minimize the chances of having to resend DNA samples, for construct greater than 25 kb, it is highly recommended that you filter the DNA before sending to us. To filter the DNA, we use the Pall Nanosep® MF Centrifugal Device 0.2 µM. Please make sure that the DNA concentration is at least 500 ng/µl after filtering.