Here's my situation - I am trying to study the chromosomal mutant phenotype of a specific protein. I can make viable homozygous mutants, but they are sterile. Each time I want to do an experiment, I have to set up a cross using heterozygous parents.
Here is my problem - there seems to be a great deal of maternal protein on the "mutant" chromosomes, that lasts until the end of the third-instar larval stage. I would like to do immunofluorescence on polytene chromosomes, so it would be lovely if there was a way to get rid of this maternal protein! The protein is frequently absent from the chromosomes if I pick extremely old larvae, but because they are so old they often appear to have defects that may not necessarily be mutant phenotypes.
I have a construct for GAL4 driven RNAi knockdown, but I'm concerned that the maternal mRNA will be translated long before the onset of zygotic transcription. We don't have the capabilities to do injections. Does anyone have any ideas for reducing maternal contribution of a protein?
And if not, does anyone know of a good driver that turns on almost immediately at the onset of zygotic transcription?
Thank you all!