Approximately just over half of γTub37C3 late-stage oocytes exhibit nucleus mis-positioning.
The chiasmate chromosomes often fail to form a single mass at the spindle midzone in γTub37C3/Df(2L)Exel6043 prometaphase I oocytes, and are instead stretched across the length of the spindle. In some cases, the chromosomes fail to align in any direction and display both abnormal invaginations and projections away from the main chromosome mass. Defects in the DNA threads that connect achiasmate chromosomes are also seen in the mutant oocytes. 86% of the mutant oocytes either lack a recognisable spindle or have an abnormal spindle; monopolar spindles are seen in 21% of cases, barrel-like spindles are seen in 25% of cases and in 32% of cases, the microtubules in the oocyte show no clear directionality and project in all directions.
Chromosomes are successfully congressed to the metaphase plate to form lemon-shaped structures in 35% of γTub37C3/Df(2L)Exel6043 metaphase I oocytes. In 56% of cases, the chromosome mass is split into multiple pieces. The spindle is reduced to a large microtubule bundle projecting from each end of the chromosome mass in 35% of cases, while in 33% of cases, no apparent microtubules are associated with the chromosomes.
The nucleus is mislocalised in 35% of γTub37C3/Df(2L)Exel6043 oocytes during stages 11 and 12 and is mislocalised in 63% of mutant oocytes during stages 13 and 14.
γTub37C1/γTub37C3 embryos show defects in anchoring of nuclei to the surface but show no defects in apical mRNA localization.
80% of eggs derived from γTub37C3/Df(2L)TE37C-7 females contain one or two robust bipolar spindles similar in size to a meiotic or mitotic spindle in wild-type eggs. A smaller proportion contain more than two of these large spindles. Nearly all spindles are anastral, lacking the radial array of microtubules at the spindle ends that are seen in wild-type eggs. Some eggs do not contain robust bipolar spindles. These eggs generally contain only a small number of minispindles with long microtubules organised about a chromosome complement that appears to be haploid or less. Minispindles are also seen in eggs with robust bipolar spindles. Microtubule structures that cannot be assigned as bipolar spindles are seen in less than 5% of eggs. These structures include half-spindles that are sometimes connected to a central microtubule organising centre (MTOC)-like structure, isolated MTOC-like structures and, rarely, structures that lack an identifiable microtubule organisation. Polar bodies similar to those found in wild-type eggs are not found in the mutant eggs. Eggs derived from γTub37C3/γTub37C1 females do not show polar body structures, but do have robust polar spindles. Ovaries dissected from γTub37C3/Df(2L)TE37C-7 or γTub37C3/γTub37C1 females yield less than 5% of the activated oocytes obtained from wild-type ovaries, when the oocytes are activated in vitro. Activated oocytes derived from γTub37C3/Df(2L)TE37C-7 females complete meiosis and assembly of polar bodies, although the polar bodies show more diffuse microtubule organisation than in wild-type activated oocytes or laid eggs.
Many unfertilized eggs laid.