FlyBase curator comment: this entry is used to capture phenotypic information when the particular allele (or allele combination) used by the author could not be determined but the context of the experiment suggests that the phenotype being described is some kind of loss of function.
neuroblast & mitotic cell cycle
Homozygous or hemizygous gwlunspecified third instar larval brain neuroblasts are mitotic progression defective, with delays in late G2/prophase and the metaphase/anaphase transition. The mitotic index in gwlunspecified third instar larval brain neuroblasts is ~2.5-fold higher than in controls, and the proportion of anaphase/telophase cells is ~10-15% that in wild-type. The fraction of cells in late G2/prophase is elevated, indicating that nuclear envelope breakdown is delayed. In addition, mutant cells in which nuclear envelope breakdown has occurred are subsequently delayed in entering anaphase. Almost all residual anaphase/telophase cells are aberrant, with lagging chromosomes or chromosome bridges. However, the spindle in gwlunspecified mutants is morphologically normal in all mitotic stages.