title: RNA, RIBOSOMAL/*BIOSYNon of ribosomal 5S RNA genes in Chironomus thummi by in situ hybridization of iodinated 5S RNA.
abstract: 5 S RNA of Chironomus thummi larvae was purified from total phenol extracted RNA by gel filtration and labelled to about 10(7) dpm/mug with carrier-free iodine-125. After hybridization in situ of 125I-5 S RNA and autoradiography only region B3c-e (containing two "normal" and two very faint bands) of chromosome II of salivary gland cells was highly labelled. In chromosomes of an animal showing pairing discontinuities a clearly "heterozygous" labelling of the 5 S RNA region was found. Region B3c-e shows no clearcut morphological signs of puffing or autoradiographically detectable 3H-uridine incorportion in spite of a continuous synthesis of 5 S RNA in salivary gland cells.
mesh_terms: D000818:Animals; D002874:Chromosome Mapping; D004175:Diptera / Q000166:cytology*; D005796:Genes; D009693:Nucleic Acid Hybridization; D012335:RNA, Ribosomal / Q000096:biosynthesis*
chemical_list: D012335:RNA, Ribosomal