Required for the correct organization of the nucleolus during development. Present in all examined cell types, including neuroblasts, ganglion mother cells, neurons, imaginal disk, epithelial cells, germline cells and embryonic cells. Present at high level in cells with high proliferation rates, such as neuroblasts and nurse cells. In the brain, it is observed at higher level in neuroblasts, ganglion mother cells and young neurons. Detected at high level in all neurons of 3-day-old adult brains (at protein level). viable but sterile. The mushroom body (MB), a functional center for learning and memory, exhibits abnormally thin axonal lobes. In neuroblasts, the nucleolus is packed more tightly, forming a dense sphere, and the nucleolar proteins such as fibrillarin and Nop60B are abnormally distributed in the interphase nucleolus. Contaminating sequence. Potential poly-A sequence. Contaminating sequence. Potential poly-A sequence.