Figure 1: Drosophila Separase protects telomeres from fusions.
(a) DAPI-stained neuroblast metaphases from wild type (inset in a) and Sse mutant (a–c) larval brains. (a–c) Examples of metaphases from Sse mutants showing different degrees of endoreduplication; some endoreduplicated chromosomes are fused at their termini generating complex linear (arrows in b and c) and ring-shaped (asterisk in a) multicentric chromosome configurations. It is worth noting that the arrows indicate the most straightforward DTAs. Scale bar, 5 μm. (d) Degree of ploidy in endoreduplicated cells of Sse mutants. (e) Frequency of TFs in Sse mutants; DTA/TC is the ratio between the number of DTAs and the total number of metaphase chromosomes (TC). It is noteworthy that the DTA/TC ratio does not change with the degree of endoreduplication. In wild-type brains, TFs and endoreduplicated metaphases were never observed. (f) Schematic representation of Drosophila Sse showing the conserved C50 peptidase domain (grey), the invariant Histidine and Cystein residues (white bars), and the 3-bp deletion that replaces F265 and G266 with a C in the Ssedft mutant (black arrow). This mutation generates a protein that is one amino acid shorter than a wild-type Sse. The arrowhead indicates the 4-bp deletion generating a premature stop codon previously identified in the 13m-281 Sse mutant allele.
