northern blot ~help - (Jan/28/2007 )

I used specific probe want to detet my gene.But i always have non-specific binding about 18s and 28s.
Does someone know how to reduce them?
thnaks

Increase the stringency of the blot - use a higher hybridisation temperature or greater concs of formaldehyde/formamide, higher salt concs should work too.

well if your gene is at that lenght, extract mRNA and do your western.
If length is different, increase salts and/or temp of hybridization