Larval ethanol exposure alters free-running circadian rhythm and per Locus transcription in adult D. melanogaster period mutants

Abstract

Alcohol consumption causes disruptions in a variety of daily rhythms, including the circadian free-running rhythm. A previous study conducted in our laboratories has shown that larval ethanol exposure alters the free-running period in adult Canton-S Drosophila melanogaster. Few studies, however, have explored the effect of alcohol exposure on organisms exhibiting circadian periods radically different than (normal) 24-h. We reared Canton-S, period long, and period short Drosophila melanogaster larvae on 10%-ethanol supplemented food, and assessed their adult free-running locomotor activity and period transcript at ZT 12. We demonstrate that in Canton-S larval ethanol exposure shortens the adult free-running locomotor activity but does not significantly alter period mRNA levels at ZT 12. Period long mutants exposed to larval ethanol had significantly shortened adult free-running locomotor activity rhythms and decreased period mRNA levels, while period short mutants lengthened their free-running rhythm and showed increased period mRNA levels at ZT 12 after being exposed to larval ethanol. These results indicate that the effects of ethanol on the circadian clock might depend upon the baseline circadian period of the organism or that period mutant gene expression is sensitive to developmental ethanol treatment.

Figure 1

Composite actograms for each of the genotype/ethanol conditions. Double-plotted composite actograms for (a) CS 0%-ethanol and (b) CS 10%-ethanol (c) perL 0%-ethanol and (d) perL 10%-ethanol (e) perS0%-ethanol (f) perS 10%-ethanol. LD bars are represented on the top of each actogram, and the shaded portion indicated DD.

Figure 2

The effects of larval ethanol exposure on CS free-running period and per transcript level. (a) Larval 10%-ethanol treatment significantly shortens the behavioral locomotor activity rhythm, (b) but not the per mRNA level, compared to 0%-ethanol receiving controls. * indicates significantly different from each other (p<0.05)

Figure 3

Larval ethanol exposure differently alters both behavioral and molecular rhythms of per mutants. (a) Larval 10%-ethanol treatment leads to lengthening and shortening of the free-running locomotor activity rhythm in perS and perL, respectively, compared to 0%-ethanol receiving controls. (b) perS shows an increase, while perL shows a decrease, in per mRNA level at ZT 12 compared to 0%-ethanol receiving controls. * indicates significantly different from each other (p<0.05).