Fig 2. The C1 domain is required for multiple CIC functions in Drosophila.

(A) Diagram of Drosophila CIC protein indicating the positions of the HMG-box and C1 domains. (B) Alignment of C1 domain sequences from Drosophila (Dm), Anopheles (Ag), Tribolium (Tc), mouse (Mm), human (Hs) and hydra (Hm). Light shading indicates similar residues. The four residues deleted by the cic⁴ mutation are indicated by a red bracket (see also S1 Fig.). (C, D) Cuticle of embryos derived from wild-type (C) and homozygous cic⁴ (D) females. The lack of patterning elements in the mutant reflects both suppression of trunk and abdominal regions as well as complete dorsalization of the embryo (see panels F and L). (E, F) Patterns of tll (green) and kni (red) mRNA expression in wild-type (E) and cic⁴ (F) embryos; nuclei are labeled with DAPI (grey). The mutant embryo shows expanded tll expression, which then causes repression of the abdominal kni domain. (G, H) Immunodetection of CIC protein in embryos from wild-type (G) and cic⁴ (H) females using anti-CIC antibody. Both backgrounds show similar levels of CIC nuclear accumulation (insets), indicating that the CIC⁴ mutant is stable but functionally inactive. (I, J) Patterns of mirr-lacZ reporter expression (green) in wild-type (I) and cic⁴ (J) stage-10 egg chambers; nuclei are labeled with DAPI (blue). Note the ventrally expanded expression of mirr-lacZ (arrowheads). (K, L) Expression of twi mRNA (yellow) in wild-type (K) and cic⁴ (L) embryos; nuclei are labeled with DAPI (grey). twi expression is severely reduced in the mutant embryo. Panels E, G, I, J and K are oriented with anterior to the left, dorsal up. (M, N) Wings from wild-type (M) and cic⁴ (N) adult flies; veins L2-L5 are indicated. The mutant displays thickened veins and ectopic vein material (asterisks). (O, P) External genitalia from wild-type (O) and cic⁴ (P) males; AP, anal plates. The cic⁴ individual exhibits a genital rotation phenotype (arrows indicate the genital arch-to-AP orientation).