Patterns of cell division and expression of asymmetric cell fate determinants in postembryonic neuroblast lineages of Drosophila.
We have studied the division of postembryonic neuroblasts (Nbs) in the outer proliferation center (OPC) and central brain anlagen of Drosophila. We focused our attention on three aspects of these processes: the pattern of cellular division, the topological orientation of those divisions, and the expression of asymmetric cell fate determinants. Although larval Nbs are of embryonic origin, our results indicate that their properties appear to be modified during development. Several conclusions can be summarized: (i) In early larvae, Nbs divide symmetrically to give rise to two Nbs while in the late larval brain most Nbs divide asymmetrically to bud off an intermediate ganglion mother cell (GMC) that very rapidly divides into two ganglion cells (GC). (ii) Symmetric and asymmetric divisions of OPC Nbs show tangential and radial orientations, respectively. (iii) This change in the pattern of division correlates with the expression of inscuteable, which is apically localized only in asymmetric divisions. (iv) The spindle of asymmetrically dividing Nb is always oriented on an apical-basal axis. (v) Prospero does not colocalize with Miranda in the cortical crescent of mitotic Nbs. (vi) Prospero is transiently expressed in one of the two sibling GCs generated by the division of GMCs. The implications of these results on cell fate specification and differentiation of adult brain neurons are discussed.
Ceron
J
J
Instituto de Neurociencias, Universidad Miguel Hernandez y CSIC, Alicante, 03550, Spain.
González
C
C
Tejedor
F J
FJ
D000818:Animals; D001921:Brain / Q000166:cytology / Q000254:growth & development; D018797:Cell Cycle Proteins / Q000235:genetics / Q000502:physiology; D002454:Cell Differentiation; D002455:Cell Division; D048429:Cell Size; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000502:physiology; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000196:embryology / Q000254:growth & development*; D017952:Ganglia, Invertebrate / Q000166:cytology / Q000254:growth & development; D018398:Homeodomain Proteins / Q000502:physiology; D019476:Insect Proteins / Q000502:physiology; D007605:Juvenile Hormones / Q000235:genetics / Q000502:physiology; D007814:Larva; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000502:physiology; D009420:Nervous System / Q000166:cytology / Q000254:growth & development; D009474:Neurons / Q000166:cytology* / Q000502:physiology*; D009479:Neuropeptides / Q000502:physiology; D009687:Nuclear Proteins / Q000235:genetics / Q000502:physiology; D014157:Transcription Factors
D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D019476:Insect Proteins; D007605:Juvenile Hormones; C107613:Mira protein, Drosophila; D009419:Nerve Tissue Proteins; D009479:Neuropeptides; D009687:Nuclear Proteins; D014157:Transcription Factors; C098678:insc protein, Drosophila; C060606:numb protein, Drosophila; C073099:pros protein, Drosophila