G to A nucleotide change at the second or third position of the wild type Trp codon leads to a nonsense mutation (exact site of mutation unspecified). The mutation was annotated at the second base of the codon.
81% of egg chambers in mio1 homozygotes have 16-polyploid nurse cells and no oocyte. These egg chambers rarely develop beyond stage 5 of oogenesis. This is a higher penetrance than seen for mio1/Df(2L)yan-J2 (64%), suggesting that mio1 is a weak antimorph.
Nup44AEP2417/+ partially suppresses the mio1/mio2 oogenesis phenotype. In contrast to mio1/mio2 single mutants, egg chambers from Nup44AEP2417/+, mio1/mio2 females frequently progress through vitellogenesis to produce mature eggs. Moreover, a small percentage of the eggs laid by Nup44AEP2417/+, mio1/mio2 females hatch and develop into viable adults.
The percentage of mio1/mio2 mutant egg chambers with an oocyte increases 6-fold in a Df(2R)ED1735/+ genetic background.
The percentage of mio1/mio2 mutant egg chambers with an oocyte increases 6-fold in a Nup44AΔ15/+ genetic background.