PCR primers

[JOHNSON YIP]

Hi there,

  I've got a question here, and wish someone can help me....

When you design PCR primers to amplify from the mRNA, you need to consider
some factors like GC content, Tm, internal 2ndary structure, 3'-end
complimentarity, etc.. What other factors you need to consider if you are
designing primers to amplify from the gene and not the mRNA??

  Also if you want yuor primer to work only on cDNA, and want to detect
whether there's any contaminate from the genomic DNA, how can you achieve
this? (Southern blotting??)

Thanks
 My address:- n1607693 at sparrow.qut.edu.au