Fig. 4. Northern blot of RNA extracted from the fifth internode down the stem counting from the last fully expanded leaf from the commercial varieties Q117, 74C42, 3 independently transformed lines transformed with sense PPO construct (574, 498, 478) and a line regenerated from tissue culture C131. The 2.2-kb band is the size of the PPO transcript. The lower half of the figure shows the intensity of the ribosomal bands in the total RNA fractionated in 1% (w/v) formaldehyde-agarose, before transfer to the nylon membrane.