The loss of germline stem cells (GSCs) in female germaria observed upon heat-shock-induced expression of Crei\I-CreIhs.PR (to introduce DNA damage) cannot be rescued by Scer\GAL4nos.PU-driven expression of BacA\p35UASp.Tag:FLAG in the mutant background.
The damage-evoked loss of GSCs upon expression of Crei\I-CreIhs.PR (induced by heat-shock to introduce DNA breaks) is rescued by combination with lokp6 or lokKD in hetero-, homo- or transheterozygosity as these double mutant flies contain significantly higher number of GSCs both at 3 days and 1 week post heat-shock compared to Crei\I-CreIhs.PR single mutants. Similarly, Scer\GAL4nos.PU-driven expression of lokGL00020 or tkvQ253D.Scer\UAS.P\T or simultaneous expression of both tkvQ253D.Scer\UAS.P\T and either saxQ263D.UASp or shgUASp.Tag:FLAG also significantly suppresses the damage-evoked GSC loss in Crei\I-CreIhs.PR flies. In contrast, this loss is further exacerbated by mei-41D3 in homo- or heterozygosity or by expression of mei-41GL00284, mei-41HMS02331 or tefuHMS02790 under the Scer\GAL4nos.PU driver, expression of either grpHMS01573 or grpHMC05162 or shgUASp.Tag:FLAG has no effect on the GSCs number in Crei\I-CreIhs.PR mutant background either in the presence or absence of DNA damage. The loss of GSCs in damaged Crei\I-CreIhs.PR germaria is slightly alleviated by combination with a single copy of p535A-1-4 but is actually made worse by p535A-1-4 homozygosity.
The number of GSCs remaining after DNA-damage has been induced is slightly higher both at 3 days and 1 week post heat-shock in Crei\I-CreIhs.PR Crei\I-CreIhs.PR/+ mutants but is much decreased in Crei\I-CreIhs.PR Crei\I-CreIhs.PR/Crei\I-CreIhs.PR mutants at the later time-point, as compared to Crei\I-CreIhs.PR-only flies.
mei-41D3;Crei\I-CreIhs.PR as well as Scer\GAL4nos.PU>tefuHMS02790;Crei\I-CreIhs.PR double mutants have fewer GSCs per germarium, whereas lokKD/+;Crei\I-CreIhs.PR, lokKD/lokKD;Crei\I-CreIhs.PR or lokKD/lokp6;Crei\I-CreIhs.PR mutants have more GSCs than wild-type controls even without the induction of DNA damage by heat-shock.
Crei\I-CreIhs.PR germaria in which DNA damage has been evoked by heat-shock accumulate cystoblast-like single cells and this accumulation is accelerated by lokp6 or lokKD heterozygosity (significantly increased number of CB-like cells observed already at 3 days post heat-shock) and is strongly enhanced by bamΔ86 heterozygosity. By contrast, both lokp6 or lokKD homo- or transheterozygosity completely abolishes the CB-like cell accumulation phenotype.