The l(1)ogre gene of Drosophila melanogaster is expressed in postembryonic neuroblasts

Previous genetic studies showed that the wild-type function of the lethal (1) optic ganglion reduced (l(1)ogre) gene in Drosophila melanogaster was needed, apparently specifically, for the generation and/or maintenance of postembryonic neuroblasts, i.e., those neuroblasts in the optic formation centers (primordia of the adult optic lobes) and giant neuroblasts scattered over the periphery of cortices of the larval central nervous system (CNS). In the present study temporal and spatial specificity of l(1)ogre expression was investigated by in situ hybridization and also immunofluorescence with polyclonal anti-l(1)ogre antibodies. l(1)ogre protein was detected, as expected, in the optic formation centers and giant neuroblasts in the larval CNS. l(1)ogre expression, however, was not specific to these neuroblasts: expression was also detected in a wide range of tissues including the CNS at many developmental stages. Examination of transcriptional pattern indicates that l(1)ogre is expressed in derivatives of the ectoderm, endoderm, and mesoderm (but not in the germ line) in two developmental contexts: (i) during and shortly after the proliferative phase and (ii) during histolysis of some larval tissues.