Plant rRNAs

[Markus Piotrowski]

Dear netters,

I'm actually doing total RNA-isolation from green plant tissue (Nicotiana 
 tabacum). When running the RNA on a gel I find at least five distinct 
bands. I know that some of them are 28S and 18S rRNA and some of them 
should derived from plastids and mitochondrial rRNA. Is there anyone out 
who can tell me:

a. Which band is which rRNA (from the top to the bottom of the    
formaldehyd agarose gel)?
b. What is the exact (+/-) size of these rRNAs?

Thank you very much in advance

Markus