scholarly journals Saturation Mapping of a Gene-Rich Recombination Hot Spot Region in Wheat

Genetics ◽  
2000 ◽  
Vol 154 (2) ◽  
pp. 823-835 ◽  
Author(s):  
Justin D Faris ◽  
Karri M Haen ◽  
Bikram S Gill
Keyword(s):  
Positional Cloning ◽  
Physical Map ◽  
Hot Spot ◽  
Chromosome Breakage ◽  
Small Chromosome ◽  
Gene Density ◽  
Chromosome 5B ◽  
High Gene ◽  
The Many ◽  
Recombination Hot Spots

AbstractPhysical mapping of wheat chromosomes has revealed small chromosome segments of high gene density and frequent recombination interspersed with relatively large regions of low gene density and infrequent recombination. We constructed a detailed genetic and physical map of one highly recombinant region on the long arm of chromosome 5B. This distally located region accounts for 4% of the physical size of the long arm and at least 30% of the recombination along the entire chromosome. Multiple crossovers occurred within this region, and the degree of recombination is at least 11-fold greater than the genomic average. Characteristics of the region such as gene order and frequency of recombination appear to be conserved throughout the evolution of the Triticeae. The region is more prone to chromosome breakage by gametocidal gene action than gene-poor regions, and evidence for genomic instability was implied by loss of gene collinearity for six loci among the homeologous regions. These data suggest that a unique level of chromatin organization exists within gene-rich recombination hot spots. The many agronomically important genes in this region should be accessible by positional cloning.

scholarly journals MOLECULAR MAPPING OF A GENE CLUSTER FLANKING THE DROSOPHILA DOPA DECARBOXYLASE GENE

Genetics ◽  
1984 ◽  
Vol 106 (4) ◽  
pp. 679-694
Author(s):  
Denise Gilbert ◽  
Jay Hirsh ◽  
T R F Wright
Keyword(s):  
Gene Cluster ◽  
Molecular Mapping ◽  
Gene Density ◽  
Dopa Decarboxylase ◽  
Chromosomal Dna ◽  
Potential Significance ◽  
High Gene ◽  
Complementation Groups ◽  
High Gene Density

ABSTRACT Nine lethal complementation groups flanking the Drosophila Dopa decarboxylase (Ddc) gene, have been localized within 100 kb of cloned chromosomal DNA. Six of these complementation groups are within 23 kb of DNA, and all ten complementation groups, including Ddc, lie within 78-82 kb of DNA. The potential significance of this unusually high gene density is discussed.

scholarly journals A4Mb High Resolution BAC Contig on Bovine Chromosome1q12and Comparative Analysis With Human Chromosome21q22

2005 ◽  
Vol 6 (4) ◽  
pp. 194-203 ◽  
Author(s):  
Cord Drögemüller ◽  
Anne Wöhlke ◽  
Tosso Leeb ◽  
Ottmar Distl
Keyword(s):  
Positional Cloning ◽  
Physical Map ◽  
Dominant Gene ◽  
Bac Library ◽  
Exact Order ◽  
Bac Contig ◽  
Nucleotide Sequence Data ◽  
New Genes ◽  
Human Genes ◽  
First Time

The bovine RPCI-42 BAC library was screened to construct a sequence-ready ~4 Mb single contig of 92 BAC clones on BTA 1q12. The contig covers the region between the genesKRTAP8P1andCLIC6. This genomic segment in cattle is of special interest as it contains the dominant gene responsible for the hornless or polled phenotype in cattle. The construction of the BAC contig was initiated by screening the bovine BAC library with heterologous cDNA probes derived from 12 human genes of the syntenic region on HSA 21q22. Contig building was facilitated by BAC end sequencing and chromosome walking. During the construction of the contig, 165 BAC end sequences and 109 single-copy STS markers were generated. For comparative mapping of 25 HSA 21q22 genes, genomic PCR primers were designed from bovine EST sequences and the gene-associated STSs mapped on the contig. Furthermore, bovine BAC end sequence comparisons against the human genome sequence revealed significant matches to HSA 21q22 and allowed thein silicomapping of two new genes in cattle. In total, 31 orthologues of human genes located on HSA 21q22 were directly mapped within the bovine BAC contig, of which 16 genes have been cloned and mapped for the first time in cattle. In contrast to the existing comparative bovine–human RH maps of this region, these results provide a better alignment and reveal a completely conserved gene order in this 4 Mb segment between cattle, human and mouse. The mapping of known polled linked BTA 1q12 microsatellite markers allowed the integration of the physical contig map with existing linkage maps of this region and also determined the exact order of these markers for the first time. Our physical map and transcript map may be useful for positional cloning of the putative polled gene in cattle. The nucleotide sequence data reported in this paper have been submitted to EMBL and have been assigned Accession Numbers AJ698510–AJ698674.

Different chromosomal distribution patterns of radiation-induced interchange breakpoints in barley: First post-treatment mitosis versus viable offspring

Genome ◽  
2001 ◽  
Vol 44 (1) ◽  
pp. 128-132 ◽  
Author(s):  
G Künzel ◽  
K I Gecheff ◽  
I Schubert
Keyword(s):  
Distribution Patterns ◽  
Gene Density ◽  
Post Treatment ◽  
Recombination Rates ◽  
Chromosomal Distribution ◽  
Chromosome Breaks ◽  
Translocation Breakpoints ◽  
High Gene ◽  
Radiation Induced ◽  
High Gene Density

Translocation breakpoints (TBs) induced by ionizing radiation are nonrandomly distributed along barley chromosomes. When first post-treatment mitoses were evaluated, centromeres and the heterochromatin-containing proximal segments tended to be more than randomly involved, and terminal segments to be less than randomly involved in translocations. Contrary to this, small chromosomal regions in median and distal arm positions, characterized by high recombination rates and high gene density, were identified as preferred sites for the origination of viable translocations, probably due to deviations in chromatin organization. Apparently, the position of a TB has an influence on the rate of viability versus elimination of the carrier cells. Surprisingly, TBs within centromeres and heterochromatin-containing segments seem to be more harmful for survival than those induced in gene-rich regions.Key words: Hordeum vulgare, radiation-induced chromosome breaks, translocation lines, breakpoint distribution.

A 1.8-Mb YAC Contig in Xp11.23: Identification of CpG Islands and Physical Mapping of CA Repeats in a Region of High Gene Density

Genomics ◽  
1994 ◽  
Vol 21 (2) ◽  
pp. 337-343 ◽  
Author(s):  
Michael P. Coleman ◽  
Andrea H. Németh ◽  
Louise Campbell ◽  
Chandrajit P. Raut ◽  
Jean Weissenbach ◽  
...  
Keyword(s):  
Physical Mapping ◽  
Cpg Islands ◽  
Gene Density ◽  
High Gene ◽  
Yac Contig ◽  
High Gene Density

Characterization of the amphioxus presenilin gene in a high gene-density genomic region illustrates duplication during the vertebrate lineage

Gene ◽  
2001 ◽  
Vol 279 (2) ◽  
pp. 157-164 ◽  
Author(s):  
Amalia Martı́nez-Mir ◽  
Cristian Cañestro ◽  
Roser Gonzàlez-Duarte ◽  
Ricard Albalat
Keyword(s):  
Genomic Region ◽  
Gene Density ◽  
Vertebrate Lineage ◽  
High Gene ◽  
High Gene Density

Genetic and contig map of a 2200-kb region encompassing 5.5 cM on chromosome 1 of Arabidopsis thaliana

Genome ◽  
1996 ◽  
Vol 39 (6) ◽  
pp. 1086-1092 ◽  
Author(s):  
Christian S. Hardtke ◽  
Thomas Berleth
Keyword(s):  
Arabidopsis Thaliana ◽  
Positional Cloning ◽  
Yeast Artificial Chromosome ◽  
Physical Map ◽  
Primary Root ◽  
Artificial Chromosome ◽  
Chromosome 1 ◽  
Rflp Markers ◽  
Caps Markers ◽  
Yac Contig

In the course of the isolation of the MONOPTEROS (MP) gene, required for primary root formation in Arabidopsis thaliana, a yeast artificial chromosome (YAC) contig encompassing approximately 2200 kilobases corresponding to 5.5 cM on the top arm of chromosome 1 was established. Forty-six YAC clones were characterized and 12 new restriction fragment length polymorphism (RFLP) markers are presented. Three new codominant amplified polymorphic sequence (CAPS) markers were generated that enabled high resolution genetic mapping and correlation of physical and genetic distances along the contig. The map contributes to the completion of a physical map of the Arabidopsis genome and should facilitate positional cloning of other genes in the region as well as studies on genome organization. We also present another set of 11 physically linked probes, as well as mapping data for additional RFLP markers within a broader interval of 10.4 cM. Key words : Arabidopsis, CAPS markers, MONOPTEROS gene, physical map, RFLP markers, YAC contig.

scholarly journals Gene density and transcription influence the localization of chromatin outside of chromosome territories detectable by FISH

2002 ◽  
Vol 159 (5) ◽  
pp. 753-763 ◽  
Author(s):  
Nicola L. Mahy ◽  
Paul E. Perry ◽  
Wendy A. Bickmore
Keyword(s):  
Spatial Organization ◽  
Cell Types ◽  
Gene Density ◽  
Epidermal Differentiation ◽  
Chromosome 1 ◽  
Chromosome Territories ◽  
Chromosome 11 ◽  
Epidermal Differentiation Complex ◽  
High Gene ◽  
Complex Locus

Genes can be transcribed from within chromosome territories; however, the major histocompatibilty complex locus has been reported extending away from chromosome territories, and the incidence of this correlates with transcription from the region. A similar result has been seen for the epidermal differentiation complex region of chromosome 1. These data suggested that chromatin decondensation away from the surface of chromosome territories may result from, and/or may facilitate, transcription of densely packed genes subject to coordinate regulation. To investigate whether localization outside of the visible confines of chromosome territories can also occur for regions that are not coordinately regulated, we have examined the spatial organization of human 11p15.5 and the syntenic region on mouse chromosome 7. This region is gene rich but its genes are not coordinately expressed, rather overall high levels of transcription occur in several cell types. We found that chromatin from 11p15.5 frequently extends away from the chromosome 11 territory. Localization outside of territories was also detected for other regions of high gene density and high levels of transcription. This is shown to be partly dependent on ongoing transcription. We suggest that local gene density and transcription, rather than the activity of individual genes, influences the organization of chromosomes in the nucleus.

scholarly journals Meiotic recombination, noncoding DNA and genomic organization in Caenorhabditis elegans.

Genetics ◽  
1995 ◽  
Vol 141 (1) ◽  
pp. 159-179 ◽  
Author(s):  
T M Barnes ◽  
Y Kohara ◽  
A Coulson ◽  
S Hekimi
Keyword(s):  
Caenorhabditis Elegans ◽  
Genetic Map ◽  
Recombination Rate ◽  
Physical Map ◽  
Gene Density ◽  
Cdna Clones ◽  
Recombination Rates ◽  
Noncoding Dna ◽  
Physical Size ◽  
C Elegans

Abstract The genetic map of each Caenorhabditis elegans chromosome has a central gene cluster (less pronounced on the X chromosome) that contains most of the mutationally defined genes. Many linkage group termini also have clusters, though involving fewer loci. We examine the factors shaping the genetic map by analyzing the rate of recombination and gene density across the genome using the positions of cloned genes and random cDNA clones from the physical map. Each chromosome has a central gene-dense region (more diffuse on the X) with discrete boundaries, flanked by gene-poor regions. Only autosomes have reduced rates of recombination in these gene-dense regions. Cluster boundaries appear discrete also by recombination rate, and the boundaries defined by recombination rate and gene density mostly, but not always, coincide. Terminal clusters have greater gene densities than the adjoining arm but similar recombination rates. Thus, unlike in other species, most exchange in C. elegans occurs in gene-poor regions. The recombination rate across each cluster is constant and similar; and cluster size and gene number per chromosome are independent of the physical size of chromosomes. We propose a model of how this genome organization arose.

scholarly journals Development of a sequence-based reference physical map of pea (Pisum sativum L.)

2019 ◽  
Author(s):  
Krishna Kishore Gali ◽  
Bunyamin Tar’an ◽  
Mohammed-Amin Madoui ◽  
Edwin van der Vossen ◽  
Jan van Oeveren ◽  
...  
Keyword(s):  
Genome Sequence ◽  
Positional Cloning ◽  
Physical Map ◽  
Repetitive Sequences ◽  
Bac Library ◽  
Artificial Chromosome ◽  
Bac Clones ◽  
Pooled Dna ◽  
Mapping Technology ◽  
Generation Sequencing

AbstractWhole genome profiling (WGP) is a sequence-based physical mapping technology and uses sequence tags generated by next generation sequencing for construction of bacterial artificial chromosome (BAC) contigs of complex genomes. The physical map provides a framework for assembly of genome sequence and information for localization of genes that are difficult to find through positional cloning. To address the challenges of accurate assembly of the pea genome (~4.2 GB of which approximately 85% is repetitive sequences), we have adopted the WGP technology for assembly of a pea BAC library. Multi-dimensional pooling of 295,680 BAC clones and sequencing the ends of restriction fragments of pooled DNA generated 1,814 million high quality reads, of which 825 million were deconvolutable to 1.11 million unique WGP sequence tags. These WGP tags were used to assemble 220,013 BACs into contigs. Assembly of the BAC clones using the modified Fingerprinted Contigs (FPC) program has resulted in 13,040 contigs, consisting of 213,719 BACs, and 6,294 singleton BACs. The average contig size is 0.33 Mbp and the N50 contig size is 0.62 Mbp. WGPTM technology has proved to provide a robust physical map of the pea genome, which would have been difficult to assemble using traditional restriction digestion based methods. This sequence-based physical map will be useful to assemble the genome sequence of pea. Additionally, the 1.1 million WGP tags will support efficient assignment of sequence scaffolds to the BAC clones, and thus an efficient sequencing of BAC pools with targeted genome regions of interest.

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