The specificity of the stem-loop RT-PCR assay. A. Gel blot analysis of pri- and mature miR156 expression. High molecular weight (H) and low molecular weight (L) RNA were purified from 20 μg of total RNA, separated by electrophoresis, transferred and hybridised with miR156 antisense probe. B. Stem-loop RT-PCR analyses of miR156 expression. 200 ng total RNA (T), high molecular weight RNA purified from 200 ng total RNA (H) and low molecular weight RNA purified from 200 ng total RNA (L) were subjected to stem-loop RT PCR. The amount of input RNA as measured by NanoDrop is indicated below. PCR cycle numbers are indicated to the left. SA, shoot apex; S, stem: L, leaf.