title: The replication of ribosomal DNA in the macronucleus of Tetrahymena.
abstract: The replication of extrachromosomal rDNA molecules from the macronucleus of Tetrahymena was studied by electron microscopy. Replication begins in the center of the palindromic molecule and proceeds by means of bidirectional fork movement toward the free ends of the molecule.
mesh_terms: D001973:Bromodeoxyuridine / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D004247:DNA / Q000235:genetics; D004261:DNA Replication; D004270:DNA, Circular / Q000235:genetics; D008854:Microscopy, Electron; D008970:Molecular Weight; D012335:RNA, Ribosomal / Q000235:genetics*; D013769:Tetrahymena pyriformis / Q000235:genetics*
chemical_list: D004270:DNA, Circular; D012335:RNA, Ribosomal; D004247:DNA; D001973:Bromodeoxyuridine