Fig. 5. Sense and antisense RNAs associated with post-transcriptional gene silencing of the carB gene. Fifteen micrograms of low molecular weight RNAs isolated from unsilenced wild-type strain (wt) or two different silenced albino transformants (a3 and a4) grown for three days under continuous illumination conditions were loaded in each lane. Ten picomoles per lane of 29-mer DNA oligonucleotide in antisense orientation (AS) and 25-mer DNA oligonucleotide in sense orientation (S) were used as size markers and to control the hybridization specificity. (A) RNA blot hybridized with a carB antisense-specific riboprobe (Figure 1A, probe a′). The same filter was re-hybridized with a carB sense-specific probe to detect the position of the 25 nt oligonucleotide (marked by an arrow). (B) Identical RNA blot hybridized with a carB sense-specific riboprobe (Figure 1A, probe a). Equal loading of the small RNA species was confirmed by EtBr staining of the predominant RNA species in the samples after the small RNAs were separated by agarose gel electrophoresis (data not shown).