l(3)IX-141 mutant third instar larvae have a much-reduced brain size and missing imaginal discs.
l(3)IX-141 mutant neuroblasts from third instar larval brains have mitotic chromosomes that are hypercondensed length-wise but appear loosely compacted with a ragged periphery. This phenotype is not rescued by allowing more time in mitosis with colchicine treatment.
l(3)IX-141 mutant polytene chromosomes from third instar larval salivary glands lack their distinctive banding, their chromosome arms appear twisted and frayed, and they are approximately half the size of wild type. It is difficult to identify an obvious chromocentre in many l(3)IX-141 mutant nuclei.
BrdU incorporation is clearly reduced in l(3)IX-141 mutant neuroblasts from third instar larval brains.
Larval neuroblasts of l(3)IX-141 mutants exhibit abnormal spindle morphology, with only 2% of mitotic cells having a normal bipolar spindle, 37% having a monopolar spindle, 34% having a disorganised spindle, and 27% having a bipolar asymmetric spindle. Mutant spindles also appear to have thicker bundles of microtubules compared to wild type. Almost no anaphase mitotic figures are observed in mutant neuroblasts, consistent with a metaphase delay or arrest.
Nearly 70% of mitotic figures in l(3)IX-141 mutant neuroblasts appear to have only one focus of centrosomal staining, often having a dumbbell shape suggesting that centrosomes have duplicated but not separated.
Germ cells fail to migrate and coalesce in l(3)IX-141 mutant embryos and mutant larvae lack gonads.
Imaginal discs of homozygous larvae are small. Defects in the cell cycle: few or no dividing cells, affects chromosome condensation and arrest of the cell cycle at metaphase.
Lethality acts at second-third instar larval stage. Fuzzy, swollen mitotic chromosomes; chromosome breaks.