Figure 7.

Numerical reconciliation of genetic and functional domains. (Top) Line c724 drives GFP expression in 33 type II cells of initial, transitional, and main segments. (Middle) Line c649 drives expression in 13 bar-shaped cells, diagnostic of initial and transitional segments (Table 2). (Bottom) When ethidium bromide is added to c724, it is transported into the cells, obscuring the view of all but the most distal 13 cells. This shows that the organic cation transport system operates in a compartment statistically indistinguishable from main segment.