Figure 8

The mRNA populations in larval and imaginal tissues are distinct. (a) Graphical representation of the number of spots with intensity differences >1.74 when imaginal and larval tissues were compared. The numbers of spots are derived from cluster analysis of the repeated experiments. All disc-to-disc comparisons are represented by red bars, whereas the disc-to-nondisc comparisons are shown in blue. EA, eye-antennal; FB, fat body; G, genital; GUT, anterior part of the midgut; H, haltere; L1, leg 1; L2, leg 2; L3, leg 3, OL, optic lobe/brain; SG, salivary gland; W, wing. (b) A plot of the level of divergence as measured by the SD of the log₂-transformed R/G ratios for all genes in 42 experiments (leaving out the wing-to-wing experiment). Of these, 25 experiments were comparisons of one imaginal disc to another (see text and Table 1) and the remaining 17 compared imaginal discs to larval tissue, that is, salivary gland, midgut, fat body and optic lobe/brain hemisphere. The disc-to-disc comparisons were placed on the lower line, whereas disc-to-nondisc comparisons are represented on the top line. All disc-to-disc experiments grouped to the left as a result of SD <1, indicating similarity of the expression profiles among the various imaginal discs. Disc-to-nondisc comparisons group to the right, with SD >1. A group of three experiments of disc-to-nondisc comparisons reveals low SDs in the range of disc-to-disc comparisons. These are the wing disc-to-optic lobe/brain hemisphere comparisons (arrow).