A Motor Function for Drosophila Gemin3 Figure 9. Disruption of mesodermal and muscle Gemin3 leads to loss of flight and flight muscle degeneration. (A) Left shows a schematic diagram of the apparatus for the flight assay. Flies are introduced at the top of the cylinder through a funnel. The height flies stick in the mineral oil coating the inside wall of the cylinder is an indication of their flight ability. Right shows a bar chart quantifying the flight performance of the indicated genotypes. Wild-type flies fly well and thus concentrate at the top of the cylinder. Flies with a mef2-GAL4 driven expression of gemin3DN and wild-type flies with clipped wings are skewed towards the bottom of the cylinder, hence illustrating their perturbed flight ability. Five independent assays were performed per genotype with 20 flies in each assay. Flies were approximately one week old. (B) Light microscopic images of sectioned resin-embedded thoraces from 3-week-old adult flies of the indicated genotype. Sections were stained with toluidine blue to visualise the tissue morphology and were taken at the same magnification. Anterior is left. Compared to wild-type controls, mef2-GAL4 driven expression of gemin3DN results in flight muscles, which are shrunken, and exhibit several breakages and large tears (arrowheads). doi:10.1371/journal.pgen.1000265.g009 This study raises the possibility of a functional interaction between Gemin3 and SMN. Loss of gemin3 phenocopies the larval mobility phenotypes observed in smn mutants [32]. Strong Gemin3 disruption in mesoderm and muscles led to striking developmental defects during metamorphosis, similar to those reported on disruption of SMN in a similar expression pattern [33]. A less severe gemin3 disruption in the developing musculature results in viable but flightless adult flies, which have flight muscle degeneration, similar to the phenotype in a hypomorphic smn mutant [34]. PLoS Genetics | www.plosgenetics.org 9 November 2008 | Volume 4 | Issue 11 | e1000265