flw6/Y flies have a survival rate of less than 1%.
flw6 homozygous mutant egg chambers generate an irregular wavy egg chamber epithelium. Mutant egg chambers are not round or ellipsoid like in wild-type but are either stretched or develop bulges.
On the rare occasion that a flw6 male fly survives to adulthood, it has severely crumpled wings. Egg chambers that are flw6 mutant within adult flies can be generated by expressing flwScer\UAS.cRa under the control of Scer\GAL4arm.PS in somatic cells, so that somatic cells express wild-type flw but the female germline does not. The flw6 homozygous egg chambers have disrupted actin cytoskeletons and abnormal nuclear structures that indicate a failure of the transfer of nurse cell contents into the oocyte at stages 10B and 11. Additionally, the ring canals, which join nurse cells to each other and to the oocyte, fail to grow properly and are therefore smaller than in wild type.
flw1/flw6 flies are completely flightless. Indirect flight muscles (IFMs) are never present in flw1/flw6 flies, but the jump muscle (tergal depressor of trochanter muscle) appears normal. Less than 1% of flw6/Y males survive to adulthood at 25oC. The period of lethality extends from the second larval instar onwards. Dying larvae are very sluggish. The muscle pattern in these larvae is clearly disrupted, many muscles are missing or weakly attached. In the few flw6/Y males that do eclose exhibit poor ambulatory ability, IFMs are absent and the tergal depressor of trochanter muscle (TDT) disorganised. Wings are crumpled and/or blistered.