Ribosomal RNA genes are abundant repetitive sequences in most eukaryotes. Ribosomal DNA (rDNA) contains many insertions derived from mobile elements including non-long terminal repeat (non-LTR) retrotransposons. R2 is the well-characterized 28S rDNA-specific non-LTR retrotransposon family that is distributed over at least 4 bilaterian phyla. R2 is a large family sharing the same insertion speci...

Comparison of 18S rDNA gene sequences is a very promising method for identification and classification of living organisms. Molecular identification and discrimination of different Dunaliella species were carried out based on the size of 18S rDNA gene and, number and position of introns in the gene. Three types of 18S rDNA structure have already been reported: the gene with a size of ~1770 bp l...

In an attempt to clarify the taxonomy of the Mycobacterium avium complex, the relationship between IS1245 RFLP, growth temperature, 16S rDNA signature sequences and the 16S-23S rDNA internally transcribed spacer (ITS) of 160 M. avium-complex isolates from different sources was investigated. All 70 isolates identified as M. avium by INNO-LiPA MYCOBACTERIA (Innogenetics, Belgium), a DNA probe tes...

Molecular approaches have revolutionized our ability to study the ecology and evolution of micro-organisms. Among the most widely used genetic markers for these studies are genes and spacers of the rDNA operon. However, the presence of intragenomic rDNA variation, especially among eukaryotes, can potentially confound estimates of microbial diversity. To test this hypothesis, bacterially cloned ...

The rDNA genes coding for ribosomal RNA (rRNA) in animals are repeat sequences with high GC content and complicated structure. Based on the sequences of human ribosomal DNA repeat unit and transcription unit and the long and accurate PCR method with LA Taq DNA polymerase and GC buffer, we were able to amplify the complicated repeat sequences of rDNA genes in Bos taurus. Three rDNA genes and 2 i...

The nuclear ribosomal repeats for the 18S, 5.8S, and 26S RNAs of two closely related Picea (spruce) species were characterized by restriction mapping and Southern blot hybridization. Restriction polymorphisms were identified in the IGS and ITS sequences; however, no polymorphism was species specific. As many as five different rDNA repeat units were observed in individual genomes. The repeat siz...

Transcription of the several hundred of mouse and human Ribosomal RNA (rRNA) genes accounts for the majority of RNA synthesis in the cell nucleus and is the determinant of cytoplasmic ribosome abundance, a key factor in regulating gene expression. The rRNA genes, referred to globally as the rDNA, are clustered as direct repeats at the Nucleolar Organiser Regions, NORs, of several chromosomes, a...