title: Sites of RNA synthesis and migration in the adrenal cortex cells of the young rat, as shown by radioautography.
abstract: The sites of RNA synthesis, processing and migration were studied with light and electron microscope radioautography in adrenal zona fasciculata cells of the young rat. Animals were injected iv with [3H]uridine and sacrificed at various time intervals. A marked radioactive peak was found in blood at the 20 min interval, later time intervals being considered as chase periods. Labelling was high over nucleoli of fasciculata cells at 1 h, with the silver grains concentrated over the fibrillar component. Simultaneous though lower peaks occurred over the condensed chromatin and the interchromatin space. Nucleolar and extranucleolar values were decreased at 8 and 24 h, most silver grains overlaying the cytoplasm at this time period. At 8 h, the granular component of the nucleolus was more heavily labelled than the fibrillar component. This sequence of events suggests a relatively slow uptake of the labelled nucleotides and slow formation of pre-rRNA molecules in the fibrillar component of the nucleolus, with the processing into smaller subunits occurring in the granular component during initial chase. Extranucleolar RNAs were synthesized simultaneously but in a smaller rate. Most nucleolar RNA was finally transferred to the cytoplasm. This pattern will serve as a basis for studying the effects of ACTH on the different steps of RNA synthesis and transport in adrenal cortex cells.
mesh_terms: D000302:Adrenal Cortex / Q000378:metabolism* / Q000648:ultrastructure; D000818:Animals; D001345:Autoradiography; D002466:Cell Nucleolus / Q000378:metabolism / Q000648:ultrastructure; D002843:Chromatin / Q000378:metabolism / Q000648:ultrastructure; D003593:Cytoplasm / Q000378:metabolism / Q000648:ultrastructure; D008297:Male; D012313:RNA / Q000096:biosynthesis*; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D002843:Chromatin; D012313:RNA