heterochromatin & nurse cell
nurse cell & nucleus
In females homozygous for CycE01672, 37+/-7% of egg chambers (n>200) contain a cell adjacent to the true oocyte with abnormally low ploidy and other oocyte-like features, and only 14 wild-type nurse cells; i.e.- one of the nurse cells is partially transformed into a second oocyte.
Mutant ovaries show an increase in heterochromatic DNA replication but no perturbations in nurse chromosome structures.
Two or three of the cystocytes differentiate as oocytes.
Nurse cell chromocenters are increased dramatically in both size and intensity. The "5-blob" nuclear stage persists in some affected nurse cells beyond endocycles 4-5, indicating retarded chromatin changes. 30% of egg chambers contained 8 instead of 16 cells: 7 nurse cells and an oocyte. 30-40% of egg chambers contain germline cysts with two germinal vesicles and 5% contain 3. Those with two germinal vesicles always include 14 nurse cells, indicating a nurse cell to oocyte transformation. The extra germinal vesicle is smaller and has a retarded development. Eggs develop one or two extra dorsal appendages, indicating that the extra germinal vesicles can provide the usual dorsalising activity. Mutant nurse cells have increased DNA content, due to the increased propagation of the (usually under-represented) heterochromatic sequences. Late replication is restored to endomitotic nurse cells (where it does not normally occur), but not to follicle cells.
CycE01672 has nurse cell phenotype, suppressible by dap[+]/dap4
Excision of the P{PZ} restores female fertility and reverts the nurse cell chromocenter phenotype.