Yi, Xiaoming (Z3C20 at ttacs3.ttu.edu) wrote: : Hi, netters, : I have posted this question a couple of days ago, but got not response. Did : anyone do PCR with a big primer like 500bp? If so, can anybody tell me what the : major difference is, what should I do to make it work? : Thanks! A 500bp primer would cost a lot more than a 20-mer . ;>