Amplified ribosomal spacer sequence: structure and evolutionary origin

J Mol Biol. 1987 Jan 5;193(1):217-22. doi: 10.1016/0022-2836(87)90639-5.


A novel class of repeated sequences consisting of tandem arrays of ribosomal spacer sequence has been discovered in a mouse genome. Comparison to normal ribosomal DNA reveals that one repeat unit consists of two separate parts of spacer sequence. This amplified spacer sequence has a pseudogene-like structure but is distinct from the previously reported pseudogenes and orphons in regions lacking coding sequences. So far the amplified spacer sequence has been found only in the BALB/c mouse genome but not in ten other laboratory strains and several wild-type mouse stocks. Surprisingly, a part of the amplified spacer sequence unit had a higher homology to the corresponding part of the ribosomal DNA sequence of Mus musculus molossinus, a Japanese wild-type mouse, than to the corresponding part of the rDNA of the BALB/c mouse. These findings suggest that the amplified spacer sequence of the BALB/c mouse might have partly originated in M. m. molossinus or in a related subspecies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Base Sequence
  • DNA, Recombinant*
  • DNA, Ribosomal*
  • Mice
  • Mice, Inbred BALB C
  • Nucleic Acid Hybridization
  • RNA, Ribosomal


  • DNA, Recombinant
  • DNA, Ribosomal
  • RNA, Ribosomal