generally in Southern blotting all of the dna does transfer and there is no need to check if it has transferred. Just probe it and get the result. Do you have some special need to check the transfer before probing?. If the dna fragment size is particularly large you can acid depurinate or over expose to uv light before transfer to get a higher efficiency of large dna transfer If you stain or view the old gel after transfer there will be no dna fluorescing in the gel indicating that transfer has taken place

Agree with Paul that if your transfer arrangement and buffers are all right then DNA is transferred to the membrane. after overnight transfer, we used to view the agarose gels under UV, before discarding to check any leftover fluorescence (indicating presence of DNA in the gels). We have always found the transfer to be efficient.

SD

Hello

Thanks for your answers. I just want to know if I can retrieve the DNA with probe or not.

Thanks