Open AccessThe arrangement of ribosomal RNA genes in Schistosoma mansoni
Author(s) -
SIMPSON Andrew J. G.,
DAME John B.,
LEWIS Fred A.,
McCUTCHAN Thomas F.
Publication year - 1984
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1984.tb07973.x
Subject(s) - biology , ribosomal rna , genetics , restriction enzyme , gene , microbiology and biotechnology , restriction map , genomic dna , 5s ribosomal rna , 5.8s ribosomal rna , plasmid , rna , ribosome , 18s ribosomal rna
The two large ribsomal RNA subunits of Schistosoma mansoni are encoded within a 10000‐base sequence, which is tandemly repeated in the schistosome genome. Restriction endonuclease digestion with Bam HI cuts the rRNA gene into three fragments, which have been cloned separately in pBR322 and used to constract a physical map of the gene. The sequence encoding the smaller rRNA subunit is about 2000 bases in length and is situated on the 5′ sie of the sequence encoding the larger subunit, which is about 4000 bases. Approximately 4000 bases of the rRNA gene are spacer and do not code for mature rRNA. There are approximately 100 copies of the rRNA gene per haploid genome of which about 10% exhibit length heterogeneity, as judged by the hybridization of the rDNA plasmids to restriction endonuclease digests of genomic DNA. These structural variants appear to contain additional DNA suquences at more than one site within the gene and are polymorphic within the species S. mansoni.