abdominal ventral sensillum campaniformium vc1 & thecogen cell
abdominal ventral sensillum campaniformium vc2 & thecogen cell
abdominal ventral sensillum campaniformium vc3 & thecogen cell
abdominal ventral sensillum campaniformium vc4a & thecogen cell
abdominal ventral sensillum campaniformium vc4b & thecogen cell
embryonic neuroblast & spindle
mitotic domain 9 & spindle
Equal size neuroblast divisions are not seen in insc22; bazdsRNA.cCa mutant neuroblasts (n = 72), or in insc22; aPKCdsRNA.cCa mutant neuroblasts (n = 65). In G-iα65AdsRNA.cCa; insc22 embryos the majority of neuroblasts undergo equal size divisions (76%, n = 39) Being mutant for insc22 enhances the penetrance of the symmetric division (9% to 31%), and reverse orientation division (2% to 11%) phenotypes seen in pon::rapsc-pon.Scer\UAS; Scer\GAL4sca-P309 embryos (n=63). In insc22, rapsP62 double mutant embryos, all neuroblasts (100%, n = 98) give rise to equal-sized daughters (R = 1.02 plus or minus 0.08, n = 30). These equal size divisions are characterized by a symmetric undisplaced mitotic spindle.
In rapsunspecified insc22 or bazunspecified insc22 double mutant neuroblasts, both centrosomes are associated with astral microtubules, with a cap structure forming over each centrosome from metaphase onwards. This phenotype is not observed in single mutants for these genes. Equal size division between daughter cells is observed in 100% of G-iα65AP8 insc22 double mutants. In G-iα65AP8 insc22 mutant neuroblasts, the spindle geometry remains symmetric even at telophase with the cleavage plane being equidistant to both centrosomes. The spindle is positioned symmetrically with both centrosomes lying in close proximity to the cell cortex.
The neuroblasts phenotype is rescued by the expression of inscA2-A3.hs.T:Zzzz\FLAG. 49% of hemisegments show duplication of the RP2 neuron at the expense of the RP2sib neuron. The RP2 neuron duplication phenotype of insc22 embryos is largely rescued by inschs.PK, insc3'RI.hs.T:Hsap\MYC, insc3'DraIII.hs.T:Hsap\MYC or insc5'NheI.hs.T:Zzzz\FLAG. The RP2 neuron duplication phenotype of insc22 embryos is not rescued by insc3'NheI.hs.T:Hsap\MYC, insc5'BsrBI.hs.T:Zzzz\FLAG or insc5'BsrBI.hs.T:Zzzz\FLAG. The RP2 neuron duplication phenotype of insc22 embryos is partially rescued by insc3'BsrBI.hs.T:Hsap\MYC, insc3'NarI.hs.T:Hsap\MYC, inscBcII.hs.T:Hsap\MYC or inscA1-A5.hs.T:Zzzz\FLAG.