title: Bombyx mori 28S ribosomal genes contain insertion elements similar to the Type I and II elements of Drosophila melanogaster.
abstract: We have examined the 28S ribosomal genes of the silkmoth, Bombyx mori, for the presence of insertion sequences. Two types of insertion sequences were found, each approximately 5 kb in length, which do not share sequence homology. Comparison of the nucleotide sequences of the junction regions with the uninserted gene reveals that one type of insertion has resulted in a 14 bp duplication of the 28S coding region at the insertion site. The location of this insertion and the 14 bp duplication are identical to that found in the Type I ribosomal insertion element of Drosophila melanogaster. The second type of insertion element is located at a site corresponding to approximately 75 bp upstream of the first type. The location of this insertion, the variability detected at its 5' junction, and a short region of sequence homology at its 3' junction suggest that it is related to the Type II element of D. melanogaster. This is the first example of a Type II-like rDNA insertion outside of sibling species of D. melanogaster, and the first example of a Type I-like rDNA insertion outside of the higher Diptera.
mesh_terms: D000818:Animals; D001482:Base Composition; D001483:Base Sequence; D012831:Bombyx / Q000235:genetics*; D003001:Cloning, Molecular; D004262:DNA Restriction Enzymes; D004251:DNA Transposable Elements; D004275:DNA, Ribosomal / Q000235:genetics*; D004331:Drosophila melanogaster / Q000235:genetics*; D005796:Genes; D012335:RNA, Ribosomal / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity
chemical_list: D004251:DNA Transposable Elements; D004275:DNA, Ribosomal; D012335:RNA, Ribosomal; D004262:DNA Restriction Enzymes