title: Transcription and motoneuron size.
abstract: Nuclear size and total RNA synthesis were compared in single lumbar motoneurons isolated from the grass frog. Transcription was found to correlate significantly, but not exclusively, with nuclear area or volume over a wide range of nuclear size, the largest nuclei having the highest mean transcriptional activity. Flow cytometric analysis of propidium iodide-stained nuclei excluded polyploidy or polyteny as an explanation for the increased transcription, but left open the possibility of a small increase in DNA with increasing nuclear size. Alternatively, motoneurons may increase transcription and nuclear size without increasing their DNA content, possibly by increasing the proportion of dispersed chromatin (euchromatin). These two mechanisms for size-related changes in RNA synthesis in motoneurons present an interesting contrast to mechanisms used by many other large animal cells.
authors.affiliation: Department of Physiology and Curriculum in Neurobiology, University of North Carolina School of Medicine, Chapel Hill 27599.
authors.forename: S
authors.initials: S
authors.lastname: Sato
authors.forename: S B
authors.initials: SB
authors.lastname: Burgess
authors.forename: D L
authors.initials: DL
authors.lastname: McIlwain
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D004247:DNA / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D005434:Flow Cytometry; D009046:Motor Neurons / Q000378:metabolism / Q000502:physiology / Q000648:ultrastructure*; D011419:Propidium; D012313:RNA / Q000378:metabolism; D011894:Rana pipiens; D013116:Spinal Cord / Q000166:cytology; D014158:Transcription, Genetic / Q000502:physiology*
chemical_list: D011419:Propidium; D012313:RNA; D004247:DNA