Loss-of-function <i>shep</i> alleles disrupt <i>gypsy</i> insulator activity at <i>ct⁶</i>.

<p>(A) Effects of <i>shep</i> mutations on the <i>ct⁶</i> phenotype. All flies are homozygous for <i>mod(mdg4)^u1</i>. At the <i>shep</i> locus, flies are wildtype (<i>shep⁺</i>), harbor a heterozygous deficiency, or contain a homozygous P-element insertion as indicated. Percent of population scored on a scale of 0–4 is indicated for each genotype. 0, no notching; 1, slight notching in one wing; 2, slight notching in both wings; 3, pronounced notching in hinge distal wing margin; 4, severe notching in both hinge proximal and distal margins. Asterisks denote P-element insertions showing extensive synthetic lethal interaction with <i>mod(mdg4)^u1</i> for which rare escapers were scored (49≤<i>n</i>≤180 for all genotypes). (B) Hemizygous alleles of <i>shep</i> affect <i>ct⁶</i>. Phenotypes of <i>ct⁶</i> of <i>shep^BG00836</i> and <i>shep^d05714</i> mutations transheterozygous with <i>Df(3L)Exel6104</i>. All flies are homozygous for <i>mod(mdg4)^u1</i>. Flies were scored in parallel with those in (A) (85≤<i>n</i>≤180). (C) Male abdominal pigmentation due to <i>y²</i> expression is unchanged in <i>mod(mdg4)^u1</i> compared to <i>shep^BG00836</i>, <i>mod(mdg4)^u1</i> flies.