We next examined whether dAlk might modulate the flies' sensitivity to ethanol-induced sedation. A Flybase search revealed two P-element insertions in Alk, f01491 (Exelixis Collection at the Harvard Medical School), located in a 5′ intron of the gene, and MB06458 (Bloomington Drosophila Stock Center), located in the 3′ untranslated region (Figure 2A). Homozygous flies carrying the f01491 insertion are not viable as adults and were therefore tested as heterozygotes. Flies carrying the MB06458 insertion are homozygous viable and appear normal. To determine whether the insertions affect dAlk protein levels, we examined protein lysates from whole flies on western blots using an antibody to dALK [27]. Flies carrying the f01491 insertion showed a 76% reduction in dALK compared to wild-type controls (Figure 2B). We did not observe a change in dALK levels in flies carrying the MB06458 insertion (data not shown). We speculate that, since this is a weaker allele, the MB06458 insertion may affect Alk expression in a subtle or more restricted, tissue-specific manner. Flies transheterozygous for f01491and MB06458 were small and sickly and could therefore not be tested behaviorally;
