Iswi2 homozygous third instar larvae show a decreased mitotic index in the brain lobes; C4da neurons show decreased dendrite complexity (decreased dendrite length and branch number); there are tilling defects between C4da neurons ddaC and v'ada.
Iswi1/Iswi2 transheterozygote males display defects in the morphology of the polytene chromosome X in larval salivary glands. The X chromosome is shorter and more compact compared to wild-type.
Flies containing eyes homozygous for Iswi2 (generated using the EGUF technique) have rough eyes of reduced size.
Polytene chromosomes of Iswi1/Iswi2 male larvae show condensation defects, particularly of the X chromosome.
Flies containing homozygous eyes in an otherwise heterozygous background (generated using the EGUF technique) have rough eyes which also show colour variegation and loss of cell identity (bristles grow in parts of the eye territory normally occupied by photoreceptors). Loss of ommatidia boundaries and orientation and reduced number of photoreceptors are seen.
Mutant imaginal disc cell populations show changes in cell cycle profiles compared to wild type, showing a significant decrease of the G[] and G[]/M peaks and an increase in the pre-G[] peak.
Mutant larval brain neuroblast cell populations show changes in cell cycle profiles compared to wild type, with a small but reproducible increase in the G[]/M peak and a shorter S phase than normal.
The male X polytene chromosome is decondensed in salivary glands of Iswi1/Iswi2 larvae, although the banding pattern is usually retained.
Iswi1/Iswi2 animals often survive until the early to mid pupal stages, and have slightly misshapen wing discs at the late third larval instar.
The X polytene chromosome is decondensed in male Iswi1/Iswi2 larvae but not in female Iswi1/Iswi2 larvae.
Mitotic chromosomes prepared from neuroblasts of Iswi1/Iswi2 third instar larvae are indistinguishable from wild type.
Animals expressing IswiK159R.Scer\UAS.T:Ivir\HA1 under the control of Scer\GAL4da.G32 and derived from Iswi2/+ females survive until late larval stages at 18[o]C but do not complete embryogenesis at 25[o]C. At 25[o]C, the embryos show defects in chromosome condensation and in the organisation of the mitotic spindle as early as nuclear cycle 12.
Iswi2 mutants have a high incidence of melanotic tumours and an increased number of larval hemocytes.
Iswi2/+ flies exhibit a wild-type number of dorsocentral bristles on the heminotum (2.0 per heminotum).
96 % of clones of Iswi2 homozygous female germ-line stem cells are lost from their stem cell niche by 17 days after induction, compared to only 35% of wild-type clones. The division rate of Iswi2 homozygous female germ-line stem cells is around 40% of wild-type, but these mutant cells show no significant increase in apoptosis. Iswi2 homozygous clone follicle stem cells exhibit only a slightly increased rate of loss from their stem cell niche in the ovary compared to wild-type.
The circulating hemocyte cell number in hemolymph isolated from Iswi1/Iswi2 mutants is increased considerably with respect to wild-type animals, having about 12500 per ul-1, compared to about 4500 in wild-type.
The X chromosome is grossly abnormal in salivary gland polytene chromosome preparations from homozygous male larvae, having a bloated appearance and an almost complete loss of the characteristic banding pattern.
All chromosomes appear normal in salivary gland polytene chromosome preparations from homozygous female larvae.
Heterozygotes are viable and phenotypically normal. Hemizygotes die during late larval or early pupal development and show no obvious homeotic transformations or other pattern defects. Homozygous clones can be observed in all body segments, although the size and frequency of clones in the genitalia, head and thoracic segments is reduced compared to controls. No homeotic transformations or other defects are seen in the clones. Germline clonal analysis indicates that loss of maternal Iswi+ function blocks oogenesis at an early stage; females carrying homozygous germline clones are not fertile. The structure of the polytene X chromosome of male Iswi1/Iswi2 larvae is much shorter and broader than normal. This alteration in structure of the X chromosome is highly penetrant and is never seen in female Iswi1/Iswi2 larvae. The polytene autosomes are often thinner than normal in both male and female mutant larvae. The structure of mitotic chromosomes of hemizygous larvae appears relatively normal.