Fig. 2. Construction and properties of baf null mutant homozygotes. (A) Alignment of the baf¹/baf¹ and baf²/baf² genomic DNAs in comparison with l(2)k10210/l(2)k10210 genomic DNA. Major restriction sites are as follows: B, BamHI; Xa, XbaI; and Xh, XhoI. Deletions generated after imprecise excision of integrated P-element (remnants are indicated by solid black bars). Open reading frames are indicated by either the stippled gray boxes [mouse pancreatic triacylglycerol lipase homolog, TL (entire coding region is shown); and the Cka protein, Cka (only the first exon is shown)] or the open boxes [BAF (entire coding region including both of two exons are shown)] between numbers 3226 (start of the first exon) and 3580 (end of the second exon) in the diagram of the l(2)k10210/l(2)k10210 genome. The insertion position of pP{lacW} in l(2)k10210/l(2)k10210 is shown by the down-pointing arrow in the l(2)k10210 diagram. The mRNA start site of the Cka protein is indicated by the down-pointing arrowhead at nucleotide (nt) 4360 in the l(2)k10210 diagram. The baf¹/baf¹ genomic DNA is deleted from nt 2991 to nt 3924; in baf²/baf², the genomic DNA is deleted from nt 864 to nt 3924. Both are replaced with P{lacW} fragments, the lengths of which are indicated in parentheses below the solid boxes. For rescue experiments, the genomic fragment between the BamHI and XhoI sites indicated by asterisks in the l(2)k10210 diagram was recovered from wild-type flies by PCR amplification. (B) Late third instar larval CNS and imaginal discs dissected from baf¹/+ or l(2)k10210/l(2)k10210, and baf¹/baf¹ or baf²/baf² animals are shown. Br, brain hemispheres; Im, imaginal discs; Ad, abdominal neuroblasts; Th, thoracic neuroblasts. Scale bar: 100 µm and applies to all panels. (C) Cell proliferation and differentiation of third instar larval brain hemispheres from baf¹/+ compared with baf¹/baf¹ and baf²/baf². A whole brain hemisphere of the baf¹/+ is illustrated both at low [baf¹/+ (L)], and high [baf¹/+ (H)] magnification. Scale bars in baf¹/+ (L) and (H), 20 µm. baf¹/baf¹ and baf²/baf² are shown at exactly the same magnification as in baf¹/+ (H). The complex optic lobe anlagen of baf¹/+ larvae is composed of outer anlage, oa; inner optic anlage, ia; medulla neuropil, mn; and medulla cell, mc.