bocks^DP01391 homozygotes exhibit nuclear positioning defects in muscles. Larval VL3 muscles present significantly shorter internuclear distances, longer nucleus-muscle edge distance, and significantly shorter distance between nuclear lines, as compared to controls; heterozygotes also show a significantly shorter internuclear distance, as compared to controls. Homozygous embryonic LT muscles exhibit nucleus clustering near the ventral end of the muscle (the initial nucleus cluster fails to separate into ventral and dorsal clusters) or unequally distributed along the muscle, but no changes in nucleus:muscle area ratio, as compared to controls.