title: Developmental regulation of nucleolus size during Drosophila eye differentiation.
abstract: When cell cycle withdrawal accompanies terminal differentiation, biosynthesis and cellular growth are likely to change also. In this study, nucleolus size was monitored during cell fate specification in the Drosophila eye imaginal disc using fibrillarin antibody labeling. Nucleolus size is an indicator of ribosome biogenesis and can correlate with cellular growth rate. Nucleolar size was reduced significantly during cell fate specification and differentiation, predominantly as eye disc cells entered a cell cycle arrest that preceded cell fate specification. This reduction in nucleolus size required Dpp and Hh signaling. A transient enlargement of the nucleolus accompanied cell division in the Second Mitotic Wave. Nucleoli continued to diminish in postmitotic cells following fate specification. These results suggest that cellular growth is regulated early in the transition from proliferating progenitor cells to terminal cell fate specification, contemporary with regulation of the cell cycle, and requiring the same extracellular signals.
authors.affiliation: Departments of Genetics, Ophthalmology and Visual Sciences, and Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, New York, USA. nbaker@aecom.yu.edu
authors.forename: Nicholas E
authors.initials: NE
authors.lastname: Baker
mesh_terms: D000818:Animals; D059447:Cell Cycle Checkpoints; D002454:Cell Differentiation; D002455:Cell Division; D019070:Cell Lineage; D002466:Cell Nucleolus / Q000378:metabolism*; D019927:Cyclin E / Q000378:metabolism; D029721:Drosophila Proteins / Q000378:metabolism; D004331:Drosophila melanogaster / Q000196:embryology* / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D053823:Hedgehog Proteins / Q000378:metabolism; D008938:Mitosis; D009154:Mutation; D017956:Photoreceptor Cells, Invertebrate / Q000166:cytology*; D012270:Ribosomes / Q000648:ultrastructure
chemical_list: D019927:Cyclin E; D029721:Drosophila Proteins; D053823:Hedgehog Proteins; C064196:dpp protein, Drosophila; C077245:hh protein, Drosophila