RNA electrophoresis - (Jul/11/2015 )

Hi everybody,

I have a question about RNA agarose gel electrophoresis. What are the extra bands that are visible above 18s and 28s rRNAs?

If they show DNA contamination, why they have the same size in different samples? As I khow total DNA can not be loaded on the gel.

Are they possible to be 45s or other rRNAs precursors?

I will be thankfull of your considiration.

It is likely that these are, as you suspected, other forms of RNA, often the other ribosomal RNAs. DNA forms a blob very high up on the gel, rather than discrete bands.

Thanks for your reply

I hope that it is true and these extra bands are other kinds of rRNAs. But because my designed primers work on both mRNA and DNA, I want to get rid of the chance of DNA contamination amplifying. Which brand of DNase I do you recommend?  Once I used DNase I, then there were not any 28s and 18s rRNA on the gel.

Thanks in advance for your help.