Arrangement of coding and non-coding sequences in the DNA molecules coding for rRNAs in Oxytricha sp. DNA of ciliated protozoa. VII
Swanton, M.T.; Greslin, A.F.; Prescott, D.M.
Chromosoma 77(2): 203-215
1980
ISSN/ISBN: 0009-5915 PMID: 6248308 Document Number: 160720
All of the genes in the macronucleus of Oxytricha sp. occur on physically separate gene-sized DNA molecules. The DNA molecule that codes for rRNA was inserted into a bacterial plasmid to study its structure and function. Restriction endo-nuclease mapping and hybridization of 125I-rRNA to gel separated DNA fragments showed that the intact rDNA is 8140 .+-. 50 base pairs (bp) in length. Reading from one end, the molecule consists of .apprx. 1540 bp of non-coding DNA, .apprx. 2100 .+-. 50 bp that code for 19S rRNA, .apprx. 3700 .+-. 50 bp that code for 25S rRNA and .apprx. 620 .+-. 50 bp of non-coding DNA. The 5.8S rRNA coding sequence (.apprx. 150 bp) occurs at 1 end of the 25S RNA coding region, but which end is not yet known. All 3 rRNA are encoded in the same strand of the DNA molecule, and transcription is in the order: 19 .fwdarw. 25S.