Examination of the fat body in Invadolysin4Y7
third instar larvae reveals a dramatic reduction in thickness and a significant reduction in the ratio of triglyceride-to-protein content. Overall mitochondrial number is not affected in these mutants. Staining with Mitotracker suggests functional defects in these mitochondria. These mitochondria also exhibit alterations in diameter and length compared to controls.
mutant third-instar larvae display an ATP level only 40% that of wild-type.
When fed on normal food, approximately 80% of Invadolysin4Y7
mutant larvae die after 5 days (prior to pupation), whereas 20% attempt pupariation. When fed Compound C, Invadolysin4Y7
larvae live for up to 7 days and attempt pupation. Although the pupae are abnormal and unable to complete metamorphosis (as they lack imaginal discs), this represents a greater longevity than on control food. Invadolysin4Y7
mutant larvae fed AICAR show no discernible change in development (with larvae dying prior to pupation and only 10% attempting pupariation).
mutant third-instar larvae display a defective response to hypoxia, appearing unresponsive to a hypoxic environment.
mutant third instar larvae have a much-reduced brain size and missing imaginal discs.
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.
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-144Y7
mutant polytene nuclei.
BrdU incorporation is clearly reduced in l(3)IX-144Y7
mutant neuroblasts from third instar larval brains.
Larval neuroblasts of l(3)IX-144Y7
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-144Y7
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-144Y7
mutant embryos and mutant larvae lack gonads.