Structure and evolution of the Cinful retrotransposon family of maize

Genome ◽  
2003 ◽  
Vol 46 (5) ◽  
pp. 745-752 ◽  
Author(s):  
Soledad Sanz-Alferez ◽  
Phillip SanMiguel ◽  
Young-Kwan Jin ◽  
Patricia S Springer ◽  
Jeffrey L Bennetzen
Keyword(s):  
Tandem Repeats ◽  
Yeast Artificial Chromosome ◽  
Repetitive Sequences ◽  
Point Mutations ◽  
Sequence Divergence ◽  
Artificial Chromosome ◽  
Major Constituent ◽  
Apparent Lack ◽  
Gene Acquisition ◽  
Functional Components

A maize cDNA clone was isolated by virtue of its intense hybridization to total maize genomic DNA, indicating homology to highly repetitive sequences. Genomic homologues were identified and subcloned from an adh1-bearing maize yeast artificial chromosome (YAC). Sequencing revealed that the expressed sequence was part of a Ty3-gypsy-type retrotransposon. We discovered and sequenced two complete retrotransposons of this family, and named them Cinful elements because they are members of a family of maize retrotransposons including Zeon-1 and the first plant transposable element sequenced, the solo long terminal repeat (LTR) called Cin1. All are defective, as Cinful-1 and Cinful-2 elements lack gag and Zeon-1 lacks pol homology. Despite the apparent lack of an intact "autonomous" element, the Cinful family has expanded to a copy number of about 18 000, representing just under 9% of the maize genome. Both point mutations and major rearrangements, including possible gene acquisition, differentiate members of the Cinful family. Cinful family members were found to have an unusual feature that we also observed in two other Ty3-class retrotransposons of teosinte and tobacco: related tandem repeats that separate their internal domains with a gag- or pol-containing homology from a 3' segment of unknown function. The conserved and variable features identified provide insights into the origin, mutational history, and functional components of this major constituent of the maize genome.Key words: Cin1, genome evolution, sequence divergence, Ty3-gypsy elements, Zeon-1.

Molecular characterization and distribution of a 145-bp tandem repeat family in the genus Populus

Genome ◽  
1999 ◽  
Vol 42 (5) ◽  
pp. 909-918 ◽  
Author(s):  
J Rajagopal ◽  
S Das ◽  
D K Khurana ◽  
P S Srivastava ◽  
M Lakshmikumaran
Keyword(s):  
Molecular Characterization ◽  
Tandem Repeat ◽  
Tandem Repeats ◽  
Populus Deltoides ◽  
Point Mutations ◽  
Sequence Divergence ◽  
Methylation Pattern ◽  
Dot Blot ◽  
Repeat Family ◽  
Sequence Comparisons

This report aims to describe the identification and molecular characterization of a 145-bp tandem repeat family that accounts for nearly 1.5% of the Populus genome. Three members of this repeat family were cloned and sequenced from Populus deltoides and P. ciliata. The dimers of the repeat were sequenced in order to confirm the head-to-tail organization of the repeat. Hybridization-based analysis using the 145-bp tandem repeat as a probe on genomic DNA gave rise to ladder patterns which were identified to be a result of methylation and (or) sequence heterogeneity. Analysis of the methylation pattern of the repeat family using methylation-sensitive isoschizomers revealed variable methylation of the C residues and lack of methylation of the A residues. Sequence comparisons between the monomers revealed a high degree of sequence divergence that ranged between 6% and 11% in P. deltoides and between 4.2% and 8.3% in P. ciliata. This indicated the presence of sub-families within the 145-bp tandem family of repeats. Divergence was mainly due to the accumulation of point mutations and was concentrated in the central region of the repeat. The 145-bp tandem repeat family did not show significant homology to known tandem repeats from plants. A short stretch of 36 bp was found to show homology of 66.7% to a centromeric repeat from Chironomus plumosus. Dot-blot analysis and Southern hybridization data revealed the presence of the repeat family in 13 of the 14 Populus species examined. The absence of the 145-bp repeat from P. euphratica suggested that this species is relatively distant from other members of the genus, which correlates with taxonomic classifications. The widespread occurrence of the tandem family in the genus indicated that this family may be of ancient origin.Key words: Satellite DNA, centromeric DNA, genome organization, phylogeny.

scholarly journals CENP-B box is required for de novo centromere chromatin assembly on human alphoid DNA

2002 ◽  
Vol 159 (5) ◽  
pp. 765-775 ◽  
Author(s):  
Jun-ichirou Ohzeki ◽  
Megumi Nakano ◽  
Teruaki Okada ◽  
Hiroshi Masumoto
Keyword(s):  
Dna Sequence ◽  
Dna Sequences ◽  
De Novo ◽  
Repetitive Sequences ◽  
Point Mutations ◽  
Artificial Chromosome ◽  
Binding Activity ◽  
Chromatin Assembly ◽  
Direct Assembly ◽  
Alphoid Dna

Centromere protein (CENP) B boxes, recognition sequences of CENP-B, appear at regular intervals in human centromeric α-satellite DNA (alphoid DNA). In this study, to determine whether information carried by the primary sequence of alphoid DNA is involved in assembly of functional human centromeres, we created four kinds of synthetic repetitive sequences: modified alphoid DNA with point mutations in all CENP-B boxes, resulting in loss of all CENP-B binding activity; unmodified alphoid DNA containing functional CENP-B boxes; and nonalphoid repetitive DNA sequences with or without functional CENP-B boxes. These four synthetic repetitive DNAs were introduced into cultured human cells (HT1080), and de novo centromere assembly was assessed using the mammalian artificial chromosome (MAC) formation assay. We found that both the CENP-B box and the alphoid DNA sequence are required for de novo MAC formation and assembly of functional centromere components such as CENP-A, CENP-C, and CENP-E. Using the chromatin immunoprecipitation assay, we found that direct assembly of CENP-A and CENP-B in cells with synthetic alphoid DNA required functional CENP-B boxes. To the best of our knowledge, this is the first reported evidence of a functional molecular link between a centromere-specific DNA sequence and centromeric chromatin assembly in humans.

scholarly journals Structure of the Chromosome VII Centromere Region in Neurospora crassa: Degenerate Transposons and Simple Repeats

1998 ◽  
Vol 18 (9) ◽  
pp. 5465-5477 ◽  
Author(s):  
Edward B. Cambareri ◽  
Rafael Aisner ◽  
John Carbon
Keyword(s):  
Neurospora Crassa ◽  
Yeast Artificial Chromosome ◽  
Fragment Length Polymorphism ◽  
Artificial Chromosome ◽  
Polymorphism Analysis ◽  
Dna Repeats ◽  
Centromere Region ◽  
Simple Repeats ◽  
Restriction Fragment Length ◽  
Repeat Induced Point Mutation

ABSTRACT DNA from the centromere region of linkage group (LG) VII ofNeurospora crassa was cloned previously from a yeast artificial chromosome library and was found to be atypical ofNeurospora DNA in both composition (AT rich) and complexity (repetitive). We have determined the DNA sequence of a small portion (∼16.1 kb) of this region and have identified a cluster of three new retrotransposon-like elements as well as degenerate fragments from the 3′ end of Tad, a previously identified LINE-like retrotransposon. This region contains a novel full-length but nonmobilecopia-like element, designated Tcen, that is only associated with centromere regions. Adjacent DNA contains portions of a gypsy-like element designated Tgl1. A third new element, Tgl2, shows similarity to theTy3 transposon of Saccharomyces cerevisiae. All three of these elements appear to be degenerate, containing predominantly transition mutations suggestive of the repeat-induced point mutation (RIP) process. Three new simple DNA repeats have also been identified in the LG VII centromere region. While Tcenelements map exclusively to centromere regions by restriction fragment length polymorphism analysis, the defective Tad elements appear to occur most frequently within centromeres but are also found at other loci including telomeres. The characteristics and arrangement of these elements are similar to those seen in theDrosophila centromere, but the relative abundance of each class of repeats, as well as the sequence degeneracy of the transposon-like elements, is unique to Neurospora. These results suggest that the Neurospora centromere is heterochromatic and regional in character, more similar to centromeres of Drosophila than to those of most single-cell yeasts.

scholarly journals Chromosomal localization of human genes for arylamine N-acetyltransferase

1994 ◽  
Vol 297 (3) ◽  
pp. 441-445 ◽  
Author(s):  
D Hickman ◽  
A Risch ◽  
V Buckle ◽  
N K Spurr ◽  
S J Jeremiah ◽  
...  
Keyword(s):  
Bladder Cancer ◽  
In Situ Hybridization ◽  
Yeast Artificial Chromosome ◽  
Chromosomal Localization ◽  
Artificial Chromosome ◽  
Acetylator Phenotype ◽  
Chromosome 8 ◽  
Slow Acetylator ◽  
Human Genes

Arylamine N-acetyltransferase is encoded at two loci, AAC-1 and AAC-2, on human chromosome 8. The products of the two loci are able to catalyse N-acetylation of arylamine carcinogens, such as benzidine and other xenobiotics. AAC-2 is polymorphic and individuals carrying the slow-acetylator phenotype are more susceptible to benzidine-induced bladder cancer. We have identified yeast artificial chromosome clones encoding AAC-1 and AAC-2 and have used the cloned DNAs as fluorescent probes for in situ hybridization. The hybridization patterns allow assignment of AAC-1 and AAC-2 to chromosome 8p21.3-23.1, a region in which deletions have been associated with bladder cancer [Knowles, Shaw and Proctor (1993) Oncogene 8, 1357-1364].

Compositional heterogeneity and patterns of molecular evolution in the Drosophila genome.

Genetics ◽  
1993 ◽  
Vol 134 (3) ◽  
pp. 837-845
Author(s):  
J P Carulli ◽  
D E Krane ◽  
D L Hartl ◽  
H Ochman
Keyword(s):  
Molecular Evolution ◽  
Base Composition ◽  
Yeast Artificial Chromosome ◽  
Strong Support ◽  
Direct Determination ◽  
Artificial Chromosome ◽  
Significant Heterogeneity ◽  
Sequence Evolution ◽  
Drosophila Genome ◽  
Eukaryotic Organisms

Abstract The rates and patterns of molecular evolution in many eukaryotic organisms have been shown to be influenced by the compartmentalization of their genomes into fractions of distinct base composition and mutational properties. We have examined the Drosophila genome to explore relationships between the nucleotide content of large chromosomal segments and the base composition and rate of evolution of genes within those segments. Direct determination of the G + C contents of yeast artificial chromosome clones containing inserts of Drosophila melanogaster DNA ranging from 140-340 kb revealed significant heterogeneity in base composition. The G + C content of the large segments studied ranged from 36.9% G + C for a clone containing the hunchback locus in polytene region 85, to 50.9% G + C for a clone that includes the rosy region in polytene region 87. Unlike other organisms, however, there was no significant correlation between the base composition of large chromosomal regions and the base composition at fourfold degenerate nucleotide sites of genes encompassed within those regions. Despite the situation seen in mammals, there was also no significant association between base composition and rate of nucleotide substitution. These results suggest that nucleotide sequence evolution in Drosophila differs from that of many vertebrates and does not reflect distinct mutational biases, as a function of base composition, in different genomic regions. Significant negative correlations between codon-usage bias and rates of synonymous site divergence, however, provide strong support for an argument that selection among alternative codons may be a major contributor to variability in evolutionary rates within Drosophila genomes.

scholarly journals An Artificially Constructed De Novo Human Chromosome Behaves Almost Identically to Its Natural Counterpart during Metaphase and Anaphase in Living Cells

2006 ◽  
Vol 26 (20) ◽  
pp. 7682-7695 ◽  
Author(s):  
Tomohiro Tsuduki ◽  
Megumi Nakano ◽  
Nao Yasuoka ◽  
Saeko Yamazaki ◽  
Teruaki Okada ◽  
...  
Keyword(s):  
Yeast Artificial Chromosome ◽  
Fluorescent Protein ◽  
De Novo ◽  
Artificial Chromosome ◽  
Time Lapse ◽  
Living Cells ◽  
Lac Repressor ◽  
Host Chromosome ◽  
Artificial Chromosomes ◽  
Spindle Midzone

ABSTRACT Human artificial chromosomes (HACs) are promising reagents for the analysis of chromosome function. While HACs are maintained stably, the segregation mechanisms of HACs have not been investigated in detail. To analyze HACs in living cells, we integrated 256 copies of the Lac operator into a precursor yeast artificial chromosome (YAC) containing α-satellite DNA and generated green fluorescent protein (GFP)-tagged HACs in HT1080 cells expressing a GFP-Lac repressor fusion protein. Time-lapse analyses of GFP-HACs and host centromeres in living mitotic cells indicated that the HAC was properly aligned at the spindle midzone and that sister chromatids of the HAC separated with the same timing as host chromosomes and moved to the spindle poles with mobility similar to that of the host centromeres. These results indicate that a HAC composed of a multimer of input α-satellite YACs retains most of the functions of the centromeres on natural chromosomes. The only difference between the HAC and the host chromosome was that the HAC oscillated more frequently, at higher velocity, across the spindle midzone during metaphase. However, this provides important evidence that an individual HAC has the capacity to maintain tensional balance in the pole-to-pole direction, thereby stabilizing its position around the spindle midzone.

A physical map with yeast artificial chromosome (YAC) clones covering 63% of the 12 rice chromosomes

Genome ◽  
2001 ◽  
Vol 44 (1) ◽  
pp. 32-37 ◽  
Author(s):  
Shoko Saji ◽  
Yosuke Umehara ◽  
Baltazar A Antonio ◽  
Hiroko Yamane ◽  
Hiroshi Tanoue ◽  
...  
Keyword(s):  
Genetic Map ◽  
Dna Markers ◽  
Yeast Artificial Chromosome ◽  
Physical Map ◽  
Genome Structure ◽  
Rice Genome ◽  
Artificial Chromosome ◽  
Physical Length ◽  
Rice Chromosomes ◽  
Yac Contig

A new YAC (yeast artificial chromosome) physical map of the 12 rice chromosomes was constructed utilizing the latest molecular linkage map. The 1439 DNA markers on the rice genetic map selected a total of 1892 YACs from a YAC library. A total of 675 distinct YACs were assigned to specific chromosomal locations. In all chromosomes, 297 YAC contigs and 142 YAC islands were formed. The total physical length of these contigs and islands was estimated to 270 Mb which corresponds to approximately 63% of the entire rice genome (430 Mb). Because the physical length of each YAC contig has been measured, we could then estimate the physical distance between genetic markers more precisely than previously. In the course of constructing the new physical map, the DNA markers mapped at 0.0-cM intervals were ordered accurately and the presence of potentially duplicated regions among the chromosomes was detected. The physical map combined with the genetic map will form the basis for elucidation of the rice genome structure, map-based cloning of agronomically important genes, and genome sequencing.Key words: physical mapping, YAC contig, rice genome, rice chromosomes.

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