Figure 2.

Proliferative potential of Khc^null eye imaginal cells. (A) Diagram of the recombination strategy used to produce Khc^null and wild-type sister clones. Mitotic recombination was induced at FRT sites (black arrowheads) in first instar larvae that were homozygous for w⁻ on the X chromosome and heterozygous for a Khc^null allele on chromosome 2. A single copy of mini-w⁺ was linked to the wild-type Khc allele (see MATERIALS AND METHODS for full genotypes). Thus, a recombinant Khc⁺/Khc⁺ cell gave rise to red eye tissue and its sister Khc^null/Khc^null cell gave rise to white eye tissue. Nonrecombinant Khc^null/Khc⁺ cells produced orange eye tissue. (B) Adult Drosophila eye containing a white Khc²⁷/Khc²⁷ eye clone (white arrow) and its red Khc⁺/Khc⁺ sister clone (black arrow). Based on their sizes, each clone contained ∼1500 cells derived from a single recombinant cell. (C) Comparison of the sizes of Khc^null/Khc^null clones (open bars) to their Khc⁺/Khc⁺ sister clones (filled bars) from 12 different sister clone pairs.