title: The genomic organization of retrotransposons in Brassica oleracea.
abstract: We have investigated the copy numbers and genomic organization of five representative reverse transcriptase domains from retrotransposons in Brassica oleracea. Two non-homologous Pseudoviridae (Ty1/copia-like) elements, two Metaviridae (Ty3/gypsy-like) elements (one related to the Athila family) and one Retroposinae (LINE) element were hybridized to a gridded BAC library, "BoB". The results indicated that the individual LTR retrotransposons (copia and gypsy-like) were represented by between 90 and 320 copies in the haploid genome, with only evidence of a single location for the LINE. Sequence analysis of the same elements against genome survey sequence gave estimates of between 60 and 570, but no LINE was found. There was minimal evidence for clustering between any of these retroelements: only half the randomly expected number of BACs hybridized to both LTR-retrotransposon families. Fluorescent in situ hybridization showed that each of the retroelements had a characteristic genomic distribution. Our results suggest there are preferential sites and perhaps control mechanisms for the insertion or excision of different retrotransposon groups.
authors.affiliation: Department of Biology, University of Leicester, LE1 7RH, Leicester, UK.
authors.forename: Karine
authors.initials: K
authors.lastname: Alix
authors.forename: Carol D
authors.initials: CD
authors.lastname: Ryder
authors.forename: Jay
authors.initials: J
authors.lastname: Moore
authors.forename: Graham J
authors.initials: GJ
authors.lastname: King
authors.forename: J S
authors.initials: JS
authors.lastname: Pat Heslop-Harrison
mesh_terms: D017360:Arabidopsis / Q000235:genetics; D015139:Blotting, Southern; D001937:Brassica / Q000235:genetics*; D022202:Chromosomes, Artificial, Bacterial; D004251:DNA Transposable Elements; D015723:Gene Library; D017343:Genes, Plant; D018745:Genome, Plant; D017403:In Situ Hybridization; D017404:In Situ Hybridization, Fluorescence; D020084:Long Interspersed Nucleotide Elements; D008856:Microscopy, Fluorescence; D009693:Nucleic Acid Hybridization; D012194:RNA-Directed DNA Polymerase / Q000378:metabolism; D018626:Retroelements / Q000235:genetics*; D020079:Terminal Repeat Sequences
chemical_list: D004251:DNA Transposable Elements; D018626:Retroelements; D012194:RNA-Directed DNA Polymerase