Figure 6. High resolution confocal microscopy of the physiologic barrier.

(A) Following crosses between BBB-specific P-GAL4 lines and UAS-GFP, progeny were injected with 10kDa red dextran. Two main GAL4 expression patterns emerged: 1) on the left, an example of a PG expressing line in which GFP expression overlaps with dextran signal; 2) on the right, an example of an SPG expressing line in which GFP and dextran fluorescence show little signal overlap.

(B) With antibodies to Moody and Mdr65, apical and basal expression of proteins expressed in the SPG can be discerned. In this example, the PG layer is labeled by 3kDa cascade blue dextran, the apical SPG membrane by Mdr65 antibody (C219, red), and the basal SPG membrane by Moody beta antibody (green).

(C) A co-injection of dextran and small molecule fluors and subsequent live confocal microscopy allows simultaneous live visualization of the chemical transport barrier (TB) and the diffusion barrier (DB) in a wild type animal. The TB is demarcated by the accumulation of BODIPY-labeled Prazocin (green), a transportable substrate. The DB is delineated by the accumulation of 10kDa red dextran.