I would say it depends on what type of genotyping this is. Is it PCR products from shrimp? Or is is a Southern blot of mouse DNA? Can you give is a few more hints?

What type of dye you use to stain DNA? We use EtBr and it gives no smear. We previously used some other substitute instead of EtBr that used to produce smear band. If you do not use EtBr, you can try it. Thanks.

• Agree with Brian
• How did you genotype ? Southern blotting or PCR; Or both ?

Thank you all for your responses.

This is a PCR from mouse tails, I used 1% agarose gel with EtBr. The loading dye is home made and I don't know the recipe. For the extraction of the DNA I use a kit from Quanta and for the PCR I also use a mix from Quanta.

These are OE Tg mice, the positive controle is also CMVcre so the lox-stop-lox is cut hence giving me that nice delta. The others are not supposed to have a positive delta since the lox-stop-lox is supposed to be in place. We think that there might have been a mutation during breeding.

We are wondering if maybe it could be something else? My water control is clean.

Thanks