Molecular characterization of FoxK mutant alleles. (A) The P element EP(3)3428 is inserted in 676 bp 5′ of the ATG (0) of FoxK. Red arrowheads indicate the primers used for sequencing exons 2–5. (B) Both FoxK⁴⁴ and FoxK¹⁶ carry a deletion of 2 bp at the insertion site of EP(3)3428 (−676ΔTA). FoxK⁴⁴ flies also contain a reinsertion of a fragment of the P element in exon 3 (green) that generates a premature Stop codon. In FoxK¹⁶, a deletion in exon 2 generates a new ORF (purple) containing a Stop codon. (C) Southern blot hybridized with a probe covering the entire FoxK coding region shows an extra band of 2.6 Kb in FoxK⁴⁴ and FoxK¹⁶ (arrow). (D and E) Stage 15 FoxK¹⁶ homozygous embryos do not stain with anti-FoxK (D, arrow), but the ventral nerve cord stains with anti-Elav and shows normal morphology (E, arrow).