39-mer primers

[Jenny Witherspoon]

 Sorry if this message appears twice I hit the wrong button and sent it
before I had finished.

 I am current trying to use a primer that is 39 base pairs long in
 a pcr reaction.  I have previously use 10-mers a gained good results (ie
 good banding patterns ).  However when I use the 39-mers I don't get any
 banding patterns.  Does any on know what PCR program and primer concentration
 would best suit these primers.  Also if anyone knows of any papers that
 use long primers I would appreciate the reference.  By the way I'm using
 Almond DNA.
 Please send any information to jwitherspoon at waite.edu.au
 thanks
Jenny