Presynaptic expression of hiwScer\UAS.fl
(under the control of Scer\GAL4elav.PLu
) resuces the deficit in both spontaneous and evoked neurotransmitter release in hiwND8
hemizygotes. The quantal content, which is estimated by the mean mEJP amplitude, is also rescued.
Expresion of hiwScer\UAS.fl
postsynaptically, under the control of Scer\GAL4G7
fails to rescue the hiwND8
synaptic overgrowth phenotype.
Expression of hiwScer\UAS.T:Avic\GFP-EGFP
throughout development, under the control of Scer\GAL4elav.Switch.PO
, results in a robust rescue of the hiwND8
/Y morphological phenotype with an approximate 77% reduction in the number of boutons, along with robust rescue of quantal content.
In the absence of RU486, which activates transcription of Scer\GAL4elav.Switch.PO
, and therefore hiwScer\UAS.T:Avic\GFP-EGFP
/Y synapses are still extremely overgrown; however, there is apparently some leaky expression because there is a 27% decrease in the number of synaptic boutons. Leaky expression leads to a nearly complete rescue of the quantal content, indicating that very low dose of hiw
are effective in rescuing synaptic function.
When RU486 is added during larval development, there is an additional approximately 25% reduction in bouton number, compared with hiwND8
/Y larvae in the absence of RU486. Compared with leaky expression, late expression of hiwScer\UAS.T:Avic\GFP-EGFP
does not lead to a significant decrease in synaptic branching or synaptic expansion in hiwND8
/Y mutants. There is a complete rescue of synaptic function, with a significant increase in quantal content compared to leaky hiwScer\UAS.T:Avic\GFP-EGFP
expression in the absence of RU486.