RNA molecular weight determination by agarose gel electrophoresis using formaldehyde as denaturant: comparison of RNA and DNA molecular weight markers.

Reliable molecular weight measurements of RNA molecules as large as 4.0 X 10(6) dalton can be made on agarose gels containing 2.2 M formaldehyde as denaturant (Lehrach et al., 1977). Both eucaryotic and procaryotic ribosomal RNAs have generally been used as molecular weight markers. However, Maniatis et al. (1982) have suggested the use of restriction fragments of DNA as convenient molecular weight markers for RNA samples run in formaldehyde/agarose gels. This communication compares RNA and DNA molecular weight markers run under identical conditions.