UASt regulatory sequences drive expression of the A isoform of orb2.

Expression of orb2^A.Scer\UAS under the control of Scer\GAL4^fru-GAL4, Scer\GAL4^c747 or Scer\GAL4^Mef2.247 restores 24 hour memory in orb2^Δ/orb2^ΔQ transheterozygotes.

Using the TARGET system (using Scer\GAL80^{ts.alphaTub84B} to suppress Scer\GAL4 expression a certain points during development) to express orb2^A.Scer\UAS (under the control of Scer\GAL4^Mef2.247) in the mushroom bodiesfully rescues long-term memory in orb2^Δ/orb2^ΔQ mutants when these flies are raised and tested at 29[o]C, but not when they are raised and tested at 18[o]C. Long-term memory is also restored when flies are raised at 18[o]C and then shifted to 29[o]C immediately after eclosion, thereby providing orb2 function only in the adults. The reciprocal experiment, in which flies are raised at 29[O]C, but shifted to 18[o]C as adults, does not restore long-term memory. Flies that are shifted up to 29[o]C just 2 hours before training show normal long-term memory, whereas those that are shifted immediately after training have no long-term memory. Conversely, flies shifted down to 18[o]C immediately after training have normal long-term memory, whereas flies shifted down to 18[o]C 24 hours before training, but then shifted up to 29[o]C immediately after training, do not.

Expression of orb2^A.Scer\UAS in the mushroom body αβ neurons with the Scer\GAL4^c739 driver, in the α'β neurons with the Scer\GAL4^c305a, or in projection neurons with Scer\GAL4^GH146 does not rescue the long-term memory defects found in orb2^Δ/orb2^ΔQ mutants.

Long-term memory is rescued in orb2^Δ/orb2^ΔQ mutants where orb2^A.Scer\UAS is expressed in the γ neurons under the control of Scer\GAL4^Tab2-201Y, Scer\GAL4¹⁴⁷¹, or Scer\GAL4^H24.