Fig. 4. BrdU incorporation in the CNS of third instar larvae lacking the baf gene. (A) Late third instar larvae of baf¹/+, baf¹/baf¹, l(2)k10210/l(2)k10210 and w¹/w¹ animals were labeled with BrdU for 15-20 hours by feeding just before dissection. Incorporated BrdU was detected with a m-mAb directed against BrdU (green, BrdU). Immunofluorescence images of the entire CNS are shown (B) For baf¹/+ and baf¹/baf¹, immunofluorescence images focused on brain hemispheres were also included. The same fields are labeled with PI to identify nuclei (red, PI/DNA). In both A and B, in baf¹/baf¹ tissues, two consecutive confocal sections are presented (indicated by brackets). (C) Incorporation of BrdU was also tested with 1.5-hours exposure of dissected late third instar larval CNS tissues in vitro. Individual nuclei of the baf¹/baf¹ CNS are observed at higher magnification. A merged image demonstrating the overlap of the green (BrdU) and red (PI/DNA) staining is also shown (yellow; Merge). Scale bars: 50 µm (A); 20 µ m (B); 5 µm (C) All images were recorded with a confocal microscope.