TGF-beta Receptors and Alcohol Sensitivity in Drosophila

Clic proteins influence ethanol-related behavior in flies and other species and also mediate TGF-β signaling. These findings suggest that Clics and the TGF-β signaling pathway might work together to modulate behavioral responses to ethanol. I used the Drosophila model to address the hypothesis that TGF-β signaling is important for ethanol sensitivity. Ethanol sensitivity was blunted by multiple transposon insertions in the TGF-β receptor gene thickveins. Collectively, however, I found no consistent correlation between expression of thickveins and altered ethanol sensitivity in flies harboring transposons. I therefore also assessed ethanol sensitivity in flies with loss of function point mutations in thickveins. Ethanol sensitivity was not altered in these additional thickveins genotypes, contrary to my major hypothesis. My analysis of thickveins suggests that TGF-β signaling might influence ethanol sensitivity, but if so there must be a complex relationship between the function of this pathway and sensitivity to alcohol

Contrasting influences of Drosophila white/mini-white on ethanol sensitivity in two different behavioral assays

Background The fruit fly Drosophila melanogaster has been used extensively to investigate genetic mechanisms of ethanol-related behaviors. Many past studies in flies, including studies from our laboratory, have manipulated gene expression using transposons carrying the genetic-phenotypic marker mini-white, a derivative of the endogenous gene white. Whether the mini-white transgenic marker or the endogenous white gene influence behavioral responses to acute ethanol exposure in flies has not been systematically investigated. Methods We manipulated mini-white and white expression via (i) transposons marked with mini-white, (ii) RNAi against mini-white and white and (iii) a null allele of white. We assessed ethanol sensitivity and tolerance using a previously described eRING assay (based on climbing in the presence of ethanol) and an assay based on ethanol-induced sedation. Results In eRING assays, ethanol-induced impairment of climbing correlated inversely with expression of the mini-white marker from a series of transposon insertions. Additionally, flies harboring a null allele of white or flies with RNAi-mediated knockdown of mini-white were significantly more sensitive to ethanol in eRING assays than controls expressing endogenous white or the mini-white marker. In contrast, ethanol sensitivity and rapid tolerance measured in the ethanol sedation assay were not affected by decreased expression of mini-white or endogenous white in flies. Conclusions Ethanol sensitivity measured in the eRING assay is noticeably influenced by white and mini-white, making eRING problematic for studies on ethanol-related behavior in Drosophila using transgenes marked with mini-white. In contrast, the ethanol sedation assay described here is a suitable behavioral paradigm for studies on ethanol sedation and rapid tolerance in Drosophila including those that use widely available transgenes marked with mini-white