cdc2B47/cdc2E1-24 animals grown at the restrictive temperature of 25[o]C die during the pupal stage.
At the restrictive temperature of 29[o]C, cdc2E1-24/cdc2B47 oocytes show prolonged prophase I at stage 13 and abnormal DNA morphology at stage 14.
When cdc2B47/cdc2E1-24 animals are raiseds at a semi-restrictive temperature (26oC), flies develop until the end of pupariation, but fail to hatch. These animals exhibit a severe loss of bristles. In addition, at 26h APF about 50% of sensory organs are composed of only two cells, lacking shaft and socket cells.
The average size of adult wing cells in homozygous clones which reach differentiation (after passing different times at the restrictive temperature) is twice (102.4%) that of control cells. Wing sectors carrying a mutant clone show an average reduction in area of 10.6% compared to controls. The average reduction in cell number for a sector carrying a mutant clone is 39.6% compared to controls. In addition to the reduction in area of the sector containing a mutant clone (autonomous effect), there is generally a reduction in the area of non-mutant sectors of the same wing (non-autonomous effect), the average reduction being 5.1% compared to controls. In 9/72 cases studied, the non-mutant territories show a slight increase in size, particularly sector C of the wing when the clone is in the P compartment. Homozygous clones in the notum fail to differentiate into chaetae, but they can differentiate to produce several trichomes per cell.
Embryos derived from homozygous females and raised at the restrictive temperature of 29oC have severe cell cycle defects.
cdc2B47/cdc2E1-24 larvae at the restrictive temperature show mitotic defects resulting in a reduction in the size of the imaginal discs and a reduction in the cell density in the optic lobe. The nuclei of the abdominal histoblasts are enlarged, and the DNA content is increased to about 16C.
cdc2B47/cdc2E1-24 females cease to lay eggs when shifted to the restrictive temperature of 29oC. Dividing cells in the ovary disappear over a period of 5 days after shifting to 29oC, while nurse cell nuclei persist and increase in size.
Mitotic figures are not present in the wings of homozygous pupae 16 hours after being shifted to the restrictive temperature of 30oC. Wings of homozygous pupae shifted to the restrictive temperature at the beginning of pupariation are of normal size 30 hours after being shifted to the restrictive temperature, and they are composed of cells which are larger than those of wild-type pupal wings raised under the same conditions. The pattern of DNA replication is normal in the pupal wings of homozygotes shifted to the restrictive temperature at pupariation. Homozygous clones in the wing induced during the second larval instar stage and shifted to the restrictive temperature at pupariation consist of cells with larger nuclei than the surrounding wild-type cells. The homozygous cdc2E1-24 cells appear to contribute normally to the adult wing, although they sometimes produce large, clustered trichomes. cdc2E1-24 flies raised at the restrictive temperature from pupariation onwards and expressing cdc2Scer\UAS.cWa under the control of Scer\GAL4en-e16E do not eclose, but the pattern of vein and intervein regions is normal 30 hours after shifting to the restrictive temperature. The anterior compartment of the wing disc is normal in size, but is composed of fewer and larger cells compared to the posterior compartment. cdc2E1-24 larvae in which cdc2Scer\UAS.cWa is expressed under the control of Scer\GAL4en-e16E shortly after the moult to third instar and then the larvae are raised at the restrictive temperature of 30oC have wing discs with fewer but very much larger cells in the anterior compartment compared to the posterior compartment.
The cdc2B47/cdc2E1-24 combination is temperature sensitive. cdc2B47/cdc2E1-24 third instar mutants the size of the central nervous system and imaginal discs is severly reduced. Many of the mutants cells in the CNS, salivary gland and imaginal discs are larger and more intensely DAPI-staining than wild type. Cell division is reduced but BrdU incorporation occurs in the salivary gland imaginal ring and CNS during the third instar. Abdominal histoblasts in cdc2B47/cdc2E1-24 larvae accumulate BrdU without increasing cell number, suggesting they are in endocycle.
The cdc2E1-24/cdc2216P combination shows temperature sensitivity: at 29oC flies fail to eclose, while at 25oC viable adults with abdominal defects eclose. Mutations at Cdc37 dominantly enhance this abdominal phenotype, causing profound derangement of abdominal structures, missing bristles, and fused segments. Mutations at Cdc37 also reduced the temperature at which the inviability of cdc2E1-24/cdc2216P takes effect.
At the restrictive temperature they die after pupariation at the larval-pupal interface. Larvae take 1-2 days longer than wild type to reach the wandering stage. Imaginal discs are missing or rudimentary and larval brains are reduced in size. Endoreplication and polytenization of larval cells is normal, as are salivary gland size and intensity of DNA staining of their polytene nuclei. This ts allele was used to demonstrate that the maternal contribution of cdc2 is required for embryonic syncytial nuclear divisions: persistent cyclin A expression in PNS is observed.