Northern blot analysis of WA sterile, maintainer and restorer rice lines for the presence of atp6 and orfB transcripts. Approximately 10 μg of total mitochondrial RNA from the leaves of sterile (6A), maintainer (6B) and restorer (R) lines were loaded on a 1.2% denaturing formaldehyde gel. (A) Equal loading of RNA samples from the three lines was shown by visualization of the ribosomal RNA bands by staining the gel in ethidium bromide before blotting. (B) Autoradiograph of the blot hybridized with the atp6 gene-specific probe. (C) Autoradiograph of the same blot after stripping and reprobing with the rice orfB gene-specific probe.