title: Small tandemly repeated DNA sequences of higher plants likely originate from a tRNA gene ancestor.
abstract: Several monomers (177 bp) of a tandemly arranged repetitive nuclear DNA sequence of Brassica oleracea have been cloned and sequenced. They share up to 95% homology between one another and up to 80% with other satellite DNA sequences of Cruciferae, suggesting a common ancestor. Both strands of these monomers show more than 50% homology with many tRNA genes; the best homologies have been obtained with Lys and His yeast mitochondrial tRNA genes (respectively 64% and 60%). These results suggest that small tandemly repeated DNA sequences of plants may have evolved from a tRNA gene ancestor. These tandem repeats have probably arisen via a process involving reverse transcription of polymerase III RNA intermediates, as is the case for interspersed DNA sequences of mammalians. A model is proposed to explain the formation of such small tandemly repeated DNA sequences.
mesh_terms: D001483:Base Sequence; D005075:Biological Evolution; D001937:Brassica / Q000235:genetics*; D004276:DNA, Satellite / Q000235:genetics*; D005786:Gene Expression Regulation; D005796:Genes; D009690:Nucleic Acid Conformation; D012320:RNA Polymerase III / Q000378:metabolism; D012343:RNA, Transfer / Q000235:genetics*; D012091:Repetitive Sequences, Nucleic Acid
chemical_list: D004276:DNA, Satellite; D012343:RNA, Transfer; D012320:RNA Polymerase III