Homozygous Exp6ebo-678 mutant flies exhibit defects in visual orientation memory. No defects are observed in heterozygotes.
Some flies expressing Exp6Scer\UAS.cTa under the control of Scer\GAL4lilli-189Y in a Exp6ebo-678 mutant background show a defective ellipsoid body neuropil.
ebo678 mutant flies exhibit a normal external appearance. The ellipsoid body (EB) is broad and flat (resembling the homologous structure in non-dipteran insects). In 90% of mutants the fan-shaped body (FB) appears to be vertically divided in the middle.
Tethered ebo678 mutants fly readily and for extended period of time which may be longer than in wild-type. Average torque traces and optomotor response appear as in wild-type. Average torque traces and optomotor response appear as in wild-type. However, the rate of torque spikes is greatly reduced in eboKS263 mutants. The overall spike rate is only about 40% of wild-type. The amplitude of the small torque oscillations in between spikes is also reduced. The size and shape of torque spikes in these mutants are not noticeably abnormal.
ebo678 mutants exhibit altered optomotor response dynamics. Upon reversal of the direction of rotation, mutant flies take longer than wild-type to shift their yaw torque to the new response level. These flies also behave abnormally in a flight simulator in which their yaw torque controls the angular velocity of the panorama. Many ebo678 flies fixate a single stripe less persistently than normal flies, some even try to fly away from it (antifixation).
In ebo678 gynandromorphs yaw torque activity, torque spike activity, on-target fixation and optomotor reversal time are all highly correlated with the phenotype of the ellipsoid body.
Mutants have impaired visual pattern memory.
Show normal ability to develop ethanol tolerance.
Flies have a number of brain defects, the exact phenotype depending on the genetic background. In the original genetic background in which it was induced, ebo678 produces the following phenotype; the calyx and peduncle are misshapen, the lobes are absent, and the ellipsoid body is open ventrally, flattened and occasionally divided. The fan-shaped body is split in many flies. When placed in a Canton S background by chromosome substitution, the mushroom body defects are initially less severe than in the original genetic background and drift towards wild-type. The central complex defects are stable and similar to the phenotype in the original genetic background.
Flight behaviour shows reduced amplitude in the small random oscillations of the torque trace (yaw torque activity). The frequency of torque spikes is significantly reduced (torque spike frequency). Dynamics of the optomotor response is altered (optomotor reversal time). Upon reversal of the direction of rotation mutant flies take longer than wild type to shift their yaw torque to the new response level. Flies also behave abnormally in the flight stimulator, in which their yaw torque controls the angular velocity of a panorama. Many flies fixate a single stripe less persistently than normal flies (on-target fixation). Gyandromorphs demonstrate the behavioural phenotypes yaw torque activity, optomotor reversal time and on-target fixation are all highly correlated with the phenotype of the ellipsoid body.
Walking and flight control are impaired.
ebo678 has abnormal optomotor response phenotype, non-enhanceable by sn3
ebo678 has abnormal optomotor response phenotype, non-suppressible by sn3
Mrtf[+]/MrtfΔ7, ebo678 has abnormal memory phenotype
ebo678 has ellipsoid body phenotype, non-enhanceable by sn3
ebo678 has fan-shaped body phenotype, non-enhanceable by sn3
ebo678 has ellipsoid body phenotype, non-suppressible by sn3
ebo678 has fan-shaped body phenotype, non-suppressible by sn3
Double heterozygous Exp6ebo-678/+; MrtfΔ7/+ flies show defects in visual orientation memory compared to wild type. No defects are observed in the ellipsoid body in these flies.
ebo678 sn3 double mutants exhibit differences in the appearance of the ellipsoid and fan-shaped bodies, compared to wild-type and exhibit behavioral defects as found in ebo678 single mutants. The ellipsoid body defect is clearly visible in 100% of the animals but is more variable, ranging from just open at the bottom, to totally dissociated into two lumps of neuropil.
No correlation is observed between the severity of the structural and behavioral defects in ebo678 sn3 gynandromorphs. Of those gynandromorphs in which the central complex can be distinguished, roughly half exhibit abnormal ellipsoid bodies and behavioral defects. Mutant yaw torque activity and torque spike frequency is found in about 39% and 64% of ebo678 sn3 gynandromorphs.
ebo678 is rescued by eboUAS.cTa/Scer\GAL4lilli-189Y
ebo678 is rescued by Scer\GAL4Alp4-c232/eboUAS.cTa
ebo678 is rescued by eboUAS.cTa/Scer\GAL4c305a
ebo678 is rescued by eboUAS.cTa/Scer\GAL4198Y
ebo678 is rescued by Scer\GAL4EB1/eboUAS.cTa
ebo678 is rescued by Scer\GAL4A19/eboUAS.cTa
ebo678 is rescued by eboUAS.cTa/Scer\GAL4hs.PU
Expression of two copies of Exp6Scer\UAS.cTa in the R3 and R4d ring neurons under the control of Scer\GAL4Aph-4-c232 rescues the visual orientation memory loss seen in Exp6ebo-678 mutant flies. No rescue is seen when only one copy of Exp6Scer\UAS.cTa is expressed. Rescue is also seen when Exp6Scer\UAS.cTa is expressed under the control of Scer\GAL4c305a (R2 and R4d ring neurons), Scer\GAL4198Y (R1), Scer\GAL4lilli-189Y (R3), Scer\GAL4EB1 (R2), Scer\GAL4ftz.ng (R4) or Scer\GAL4A19 (R4m).
Exp6ebo-678/Y mutant flies expressing Exp6Scer\UAS.cTa under the control of a temperature sensitive Scer\GAL4hs.PU driver show wild type memory behaviour and have an intact ellipsoid body neuropil when raised at the permissive temperature of 25[o]C. When raised at 18[o]C (the restrictive temperature) the flies do not show any visual orientation memory. However when these flies are shifted back to the permissive temperature and tested again the following day visual orientation memory is intact. 40% of these flies show ellipsoid body defects. When Exp6ebo-678/Y mutant flies expressing Exp6Scer\UAS.cTa under the control of Scer\GAL4hs.PU are raised at 25[o]C, but transferred to 18[o]C for 72hrs shortly after eclosion, the flies have defective visual orientation memory. Some, but not all, of these flies show ellipsoid body defects.
Expression of Exp6Scer\UAS.cTa under the control of either Scer\GAL4c305a or Scer\GAL4lilli-189Y and restricted to the adult stages using Scer\GAL80ts.αTub84B is unable in rescue of the visual orientation phenotype seen in Exp6ebo-678 mutant flies. If the flies are then shifted to the restrictive temperature overnight and retested the phenotype is no longer seen.
Expression of one copy of Exp6Scer\UAS.cTa under the control of Scer\GAL4Cha.7.4 fully rescues the visual orientation memory defects seen in Exp6ebo-678 mutant flies. The same is seen when two copies of Exp6Scer\UAS.cTa are expressed under the control of Scer\GAL4Gad1.3.098. Both drivers are also able to rescue the histological ellipsoid body defects.
The following alleles can be ranked, with respect to the severity of the defects observed in flight control behavior, from weak to strong, as follows: ebo[1041] > ebo[KS263] > ebo[678].