Fig. 7. Cbs fails to localize to DNA during mitosis in Arf72A mutants. The mutant allele Arf72A¹, an embryonic recessive lethal mutation, was used to investigate the loss of GRIP function during embryogenesis. Embryos that were immunostained with antibodies against microtubules (green), Cbs (red), and Cnn (blue) show that during prophase (A), metaphase (B), and telophase (C), Cbs forms cytoplasmic particles, but never associate with DNA during mitosis. Centrosome replication and maturation is usually normal in early embryos, although some defects (arrowheads in B) are present. Most Arf72A¹ mutants fail during cycle 13 and 14, as shown in embryos stained for Cnn (D,F, green) or Lva (E, green), Cbs (A-F, red), and DNA (A-F, blue). (D) In embryos with low levels of Cbs, adjacent centrosomes fuse during anaphase (arrowheads), and the start of telophase is delayed. (E) At cellularization Cbs is present as a weak haze above nuclei and Lva is undetectable. In addition, nuclear fallout is extremely high, although it is not as severe as the RNAi phenotype. (F) Cellular embryos have a significant reduction in cell number, posses many aneuploid nuclei and mitotic domains have many monopolar spindles (arrowheads). Arf72A¹-mutant embryos all fail prior to the completion of cuticle secretion. Bars, 40 µM (A-C,E); 20 µM (D,F).