Tissue specific expression of the Drosophila Adh gene: a comparison of in situ hybridization and immunocytochemistry.

The tissue specific patterns for Drosophila melanogaster alcohol dehydrogenase (Adh) mRNA and protein expression were determined using in situ hybridization and immunocytochemical techniques. Alcohol dehydrogenase mRNAs were localized in thin sections of frozen tissue using the hybridization of single stranded RNA probes. Alcohol dehydrogenase protein was identified in frozen tissue samples using ADH antisera, a biotinylated secondary antibody, and streptavidin conjugated to horseradish peroxidase. In tissues such as fat body, gastric caeca, and adult cardiac valve, the patterns of expression for ADH protein and mRNA were identical. Other tissues such as oocytes, nurse cells, imaginal disks, and brain show levels of Adh mRNA that are lower than or equivalent to those observed in the previously mentioned tissues, but they exhibit little or no ADH protein. The lack of concordance between Adh mRNA and ADH protein expression in oocytes and nurse cells may reflect the packaging of maternal mRNAs (but not ADH protein) for use in early development. The reason(s) for the other discrepancies in protein and mRNA expression are not known at this time but may be due to post-transcriptional regulation in these specific tissues.