Fig. 7. Sister-chromatid separation occurs in cells depleted of IDA. Sister-chromatid separation is observed in brain squashes from an ida^k1-449 mutant in which chromosomes are not hypercondensed (arrows, A). Hoechst staining of untreated Kc cells (B) is compared with cells treated with dsRNA specific for ida (C). Control cells retain normal chromosome morphology (B), while RNAi treated cells contain chromosomes with hypercondensed morphology and separated sister chromatids (arrowheads, C). A rarely occurring four-lobed structure, or unseparated chromatid pair is designated by an arrow (C). RNAi phenocopies the chromosome hypercondensation observed in ida null mutants.