DNA-replication/DNA-damage-dependent centrosome inactivation in Drosophilaembryos

During early embryogenesis of Drosophila melanogaster, mutations in the DNA -replication checkpoint lead to chromosome-segregation failures. Here we sh ow that these segregation failures are associated with the assembly of an a nastral microtubule spindle, a mitosis-specific loss of centrosome function , and dissociation of several components of the gamma-tubulin ring complex from a core centrosomal structure. The DNA-replication inhibitor aphidicoli n and DNA-damaging agents trigger identical mitotic defects in wild-type em bryos, indicating that centrosome inactivation is a checkpoint-independent and mitosis-specific response to damaged or incompletely replicated DNA, We propose that centrosome inactivation is part of a damage-control system th at blocks chromosome segregation when replication/damage checkpoint control fails.