Dietary effect of carbohydrates on amylase expression in Drosophila melanogaster

Abstract

Carbohydrates effect on amylase expression was analyzed in four representative strains among 27 laboratory strains that represent a range of naturally occurring amylase variants of Drosophila melanogaster in Korea. B1, B3, B4 and C6 strains showed different levels of total amylase activity and electrophoretic patterns. Amylase activity was repressed by dietary glucose in a strain-specific manner and this reduced enzyme activity reflects a reduction in the quantity of amylase protein rather than an inhibition of enzyme activity. All four strains had high levels of amylase activity with starch-treated or no-treated media. There were shown higher level of amylase activity and higher inducibility, especially in starch-treated B4. In the strains carrying a duplication of Amy structural gene, two isozyme forms of amylase could be differentially expressed by dietary carbohydrates, which was eminently shown by AMY1,3 in the electrophoresis pattern. Using competitive RT-PCR, this dietary-dependent activity change was found to be regulated at the transcription level and it suggests that the regulatory systems responsible for the response to environment expression are different among strains of Drosophila melanogaster.