rRNA sizes

[marion at SMTPLINK.IPFW.INDIANA.EDU]

          I am running total RNA through formaldehyde gels and
          staining with EtBr.  I see 5 bands of ribosomal RNA.  Can
          someone tell me the sizes of these bands?  I've tried both
          RNA and DNA molecular weight markers in these gels and
          usually only see a smear.  Is there a way to treat the
          marker to get clear separation of the bands?

          Thank you.
          Amy Marion