pnutXP flies in which pnuths.PN is expressed using daily heat shocks during larval and pupal development survive to adulthood. Female flies efficiently produce eggs. However, in most crosses of these females to either wild-type or pnutrN498/+ males, all of the embryos die without hatching, even when heat shocks are continued for 1 to 5 days after eclosion of the adult flies. Events prior to gastrulation appear to occur normally in embryos derived from a cross of pnutXP females carrying pnuths.PN (and rescued to adulthood by daily heat shock) with either wild-type or pnutXP/+ males; a layer of cleared cytoplasm forms at the cortex and cellularisation begins and proceeds evenly over the entire embryo at a normal speed and depth, although the cellularisation front is typically somewhat less well defined than in wild-type embryos. Global defects are generally not seen until the onset of gastrulation, when an ectopic fold is often seen anterior to the cephalic furrow. In addition, the posterior midgut plate often migrates to the left or right of the embryo instead of dorsally.
Dissection of the third instar larvae revealed severely reduced imaginal discs. Mutant brains contain a large number of polyploid cells. Most often these cells are tetraploid, but a poidy of 8 or more has been observed. Nucler to cytoplasm ratio measurements indicated a failure in cytokinesis. Large multinucleate cells were found in all imaginal tissues examined, with most severe effects in the lymph glands and imaginal rings of the salivary glands, in which nearly all cells contain multiple nuclei.