<p>A The ball test see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0000122#pone.0000122.s012" target="_blank">Videos S10</a>–<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0000122#pone.0000122.s014" target="_blank">S12</a>. The abilities of flies to catch, maintain and rotate a polystyrene ball were tested. The number of individuals tested males only is indicated in upper case after the genotype. Each male performed each of the tests three times. The number of asterisks max. 5 illustrates the average performance. Notice that the RNAi-based attenuation of <i>lb</i> leads to a reduced ability to catch about 20% of failures and especially to maintain the ball about 60% of failures with slower and irregular rotations. Defects in catching, maintaining and rotating the ball were comparatively stronger in flies overexpressing <i>lb</i>. About 60% of flies were unable to catch the ball and more than 80% lost it in less than 30 s. B The ‘leg-print’ test for walking pattern. Two-day old flies were allowed to walk on a carbon-soot coated glass slide and their tracks were examined. The direction of movement is towards the top of each panel. The imprints made by the first 1 second 2 and third leg 3 of the left hemisegment are marked in each panel. Wild type flies B′ show a stereotypic pattern of prints, a consequence of a ‘tripod’ gait. In male flies where UAS-lbRNAi expression is under the control of the 1151GAL4 driver B″ the legs are held closer to the body and the leg-print is the consequence of a shuffling gait. In male flies where UAS-lbe expression is under the control of the 1151GAL4 driver the pattern of prints B′″ illustrates a bias towards one side, a consequence of the legs being abnormally positioned with respect to the body.</p
