Developmental expression of choline acetyltransferase mRNA in Drosophila.

We have measured the steady state levels of choline acetyltransferase (ChAT, EC 2.3.1.6) mRNA during different developmental stages of Drosophila melanogaster using a ChAT specific cRNA probe. ChAT mRNA was first detected approximately 6-7 h after oviposition, increased until the 1st-2nd larval instar, decreased into early pupal stages and increased again during late pupation, reaching a maximum in adults. Northern analysis showed a major RNA band with a Mr of 4.7 kilobases and Western analysis also showed a single major 75 kD protein band at all developmental stages. Our results support the hypothesis that a major point of regulation of ChAT expression may be at the transcriptional level.