Fig. 3. Transgene locus structure in non-expressing and expressing tissue. (top) Line E. (bottom) Line F. (Left) Chromosomes with transgene loci. Two loci very close together are visible in line E (arrowheads); visualized using a probe against genomic fragments of 1Ax1 and 1Dx5. Line F contains two chromosomes with transgene loci; visualized using a probe against vector sequence. Tissue sections of line E and F were hybridized with pHMW-1Ax1 and pHMW-1Dx5 to detect the transgene loci in the diploid root (as non-expressing tissue) and in the triploid endosperm at 6 dpa (before the onset of expression) and 13 dpa (after the onset of expression). The image shows projections of serial confocal sections through one layer of nuclei. A blue line is drawn around the edge of each nucleus. The insertion sites in E are visible as one or two foci in root tips and young endosperm, whereas each locus in line F is visible as one focus. In expressing endosperm tissue, the loci in both lines are decondensed into many foci. Bar, 10 µm; section spacing is 0.6 µm.