THE DROSOPHILA ANACHRONISM LOCUS - A GLYCOPROTEIN SECRETED BY GLIA INHIBITS NEUROBLAST PROLIFERATION

The Drosophila anachronism (ana) locus controls the proliferation of n euroblasts, neuronal stem cells that give rise to the central nervous system. In ana mutants, quiescent postembryonic central brain and opti c lobe neuroblasts enter S phase precociously. ana encodes a novel sec reted protein of 474 amino acids that is expressed not in the affected neuroblasts, but rather in a subclass of neighboring glial cells. The se studies argue for an important role for glia in negatively regulati ng proliferation of neuronal precursor cells, thereby controlling the timing of postembryonic neurogenesis.