Egg chamber morphology and oocyte determination appear normal and the overall pattern of microtubule polarity in the oocyte is normal in

hemizygotes.

In the majority of wisp^14-1299/Df(1)RA47 oocytes, metaphase I

arrest is not maintained and the chromosomes separate aberrantly.

With very high frequencies, the chromosomes are dispersed along the

length of the spindle, resembling neither metaphase I arrest nor anaphase

I. The shapes of the spindles are often distorted due to unequal numbers

of chromosomes on each spindle arm. The spindles often appear ragged,

with microtubule spurs extending into the cytoplasm, associated with

lost chromosomes. The 4th chromosomes are often separated from the

main mass, either both being present at one pole (indicating nondisjunction)

or displaced in the cytoplasm. Separation of homologous chromosomes

is seen in some cases.

In embryos derived from wisp^14-1299/Df(1)RA47 hemizygous females

the position of the meiosis II tandem spindles is variable, often near

the centre of the embryo aligned parallel (rather than perpendicular)

to the anterior-posterior axis of the embryo. Chromosome positioning

defects occur on mutant meiosis II spindles; chromosomes are often

dispersed along the entire length of the spindle, in contrast to wild

type where they are aligned in tight bundles during metaphase and move

to opposite poles during anaphase II. Displaced chromosomes, usually

4th chromosomes, are often found near mutant meiosis II spindles, associated

with small ectopic spindles. The meiosis II central microtubule organising

center (MTOC) is defective and is often not detectable.

Embryos derived from wisp^14-1299/Df(1)RA47 hemizygous females

usually complete meiosis II, since the four products of meiosis in

interphase are often seen. The embryos arrest after completion of

meiosis II, before pronuclear fusion. These eggs are fertilised.

The sperm aster is dramatically reduced. The female meiotic products

and the sperm pronucleus enter interphase, but the female pronucleus

does not migrate towards the male pronucleus, with one or both centrosomes

displaced in the nearby cytoplasm, and one to four long, wispy, acentriolar

bipolar spindles associated with the products of female meiosis (like

polar bodies, these nuclei often fuse). These acentriolar spindles

have the microtubule density characteristics of meiotic spindles and

also have structural abnormalities such as bent, twisted ends and occasional

spurs associated with migrant chromosomes. Differences in size, shape,

microtubule density, position of the centrosomes and number and distribution

of chromosomes are seen between the wild-type first division mitotic

spindle and the mitotic spindle associated with the male pronucleus

in embryos derived from wisp^14-1299/Df(1)RA47 hemizygous females.

The mutant mitotic spindle has certain meiotic-like characteristics;

the density of microtubules is highest in the centre of the spindle

and it is long and tapered like a meiotic spindle. Unlike in wild

type, the chromosomes of the mutant mitotic spindle are usually spread

out unevenly across the long axis, without separation of individual

chromatids. The chromosomal array does not resemble either metaphase

or anaphase. One or both centrosomes are often detached from the spindle

poles and mispositioned nearby in the cytoplasm. All centrosomes either

lack astral microtubules or are associated with abnormally short astral

microtubules. Only one or two centrosomes are ever seen in these embryos,

indicating that the centrosome duplicates just once.

Lays eggs.

Homozygous females lay eggs that fail to hatch.