title: Balbiani ring hnRNP substructure visualized by selective staining and electron spectroscopic imaging.
abstract: The Balbiani Rings (BR) in the polytene chromosomes of Chironomus salivary glands are intense sites of transcription. The nascent RNPs fold during transcription into 40-50-nm granules, containing in the mature transcript approximately 37-kb RNA. Using a new nucleic acid specific stain, osmium ammine B on Lowicryl sections, in combination with electron energy filtered imaging of sections containing BR granules, we demonstrate a RNA-rich particulate substructure (10-nm particle diameter; 10-12 particles per BR granule). Elemental imaging supports that these particles are enriched in phosphorus. The possible relationship of these RNA-rich particles to ribonucleosomes is discussed, as well as models for their arrangement in the mature BR granules.
authors.affiliation: University of Tennessee-Oak Ridge Graduate School of Biomedical Sciences, Biology Division 37831-8077.
authors.forename: A L
authors.initials: AL
authors.lastname: Olins
authors.forename: D E
authors.initials: DE
authors.lastname: Olins
authors.forename: D P
authors.initials: DP
authors.lastname: Bazett-Jones
mesh_terms: D000818:Animals; D002683:Chironomidae / Q000648:ultrastructure*; D002875:Chromosomes / Q000648:ultrastructure*; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D006651:Histocytochemistry; D008854:Microscopy, Electron / Q000379:methods; D008961:Models, Structural; D009992:Osmium; D017892:Osmium Compounds; D000644:Quaternary Ammonium Compounds; D012261:Ribonucleoproteins / Q000648:ultrastructure*; D012469:Salivary Glands / Q000648:ultrastructure*; D013052:Spectrometry, X-Ray Emission; D013194:Staining and Labeling
chemical_list: D034441:Heterogeneous-Nuclear Ribonucleoproteins; D017892:Osmium Compounds; D000644:Quaternary Ammonium Compounds; D012261:Ribonucleoproteins; C058639:osmium ammine B; D009992:Osmium