title: Identification and mapping of expressed genes, simple sequence repeats and transposable elements in centromeric regions of rice chromosomes.
abstract: The genomic sequences derived from rice centromeric regions were analyzed to facilitate the comprehensive understanding of the rice genome. A rice centromere-specific satellite sequence, RCS2/TrsD/CentO, was used to screen P1-derived artificial chromosome (PAC) and bacterial artificial chromosome (BAC) genomic libraries derived from Oryza sativa L. ssp. japonica cultivar Nipponbare. Physical maps of the centromeric regions were constructed by DNA fingerprinting methods and the aligned clones were analyzed by end sequencing. BLAST analysis revealed the composition of genes, centromeric satellites and other repetitive elements, such as RIRE7/CRR, RIRE8, Squiq, Anaconda, CACTA and miniature inverted-repeat transposable elements. Fiber-fluorescent in situ hybridization analysis also indicated the presence of distinct clusters of RCS2/TrsD/CentO satellite interspersed with other elements, instead of a long homogeneous region. Several expressed genes, sequences representative of ancestral organellar insertions, relatively long simple sequence repeats (SSRs), and sequences corresponding to 5S and 45S ribosomal RNA genes were also identified. Thirty-one gene sequences showed high-similarity to rice full-length cDNA sequences that had not been matched to the published rice genome sequence in silico. These results suggest the presence of expressed genes within and around the clusters of RCS2/TrsD/CentO satellites in unsequenced centromeric regions of the rice chromosomes.
authors.affiliation: National Institute of Agrobiological Sciences, 1-2 Kannondai 2-chome, Tsukuba, Ibaraki 305-8602, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Mizuno
authors.forename: Kazue
authors.initials: K
authors.lastname: Ito
authors.forename: Jianzhong
authors.initials: J
authors.lastname: Wu
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Tanaka
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kanamori
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Katayose
authors.forename: Takuji
authors.initials: T
authors.lastname: Sasaki
authors.forename: Takashi
authors.initials: T
authors.lastname: Matsumoto
mesh_terms: D002503:Centromere / Q000235:genetics*; D022202:Chromosomes, Artificial, Bacterial; D032461:Chromosomes, Plant / Q000235:genetics / Q000648:ultrastructure*; D004251:DNA Transposable Elements / Q000235:genetics*; D018744:DNA, Plant; D018895:Microsatellite Repeats; D012275:Oryza / Q000235:genetics*; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics*
chemical_list: D004251:DNA Transposable Elements; D018744:DNA, Plant