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YAC clone contigs surrounding the Zfx and Pola loci on the mouse X chromosome.

Pulsed-field mapping of a number of DNA markers in the Pola-Zfx region of the mouse X chromosome has established a genomic restriction map extending over 1.4 Mb. A number of YAC clones from the Pola-Zfx region have been isolated from three mouse YAC libraries--first, a mouse C57BL/10 partial R1 YAC library constructed in a yeast strain carrying a rad52 mutation (Chartier et al. (1992) Nature Genetics 1: 132-136); second, a mouse C3H partial R1 library (Larin et al. (1991) Proc. Natl. Acad. Sci. USA 88: 4123-4127); and third, a mouse C57BL/6 partial R1 library (Burke et al. (1991) Mamm. Genome 1:65). Six YAC clones encompass the Zfx-Pola region, confirming the linkage of the Pola and Zfx loci and establishing a physical map order in this region of cen-Pola-DXCrc140-DXCrc57-Zfx-tel. The close linkage of Pola and Zfx in the mouse genome suggests that the POLA and ZFX loci must also be closely linked on the human X chromosome.

Animals↗

A 1.7-megabase sequence-ready cosmid contig covering the TSC1 candidate region in 9q34.

The disease gene TSC1 has been genetically mapped to human chromosome region 9q34, in a 4-cM interval between the markers D9S149 and D9S114. Within this interval there is conflicting genetic evidence as to the finer localization of the gene. We have used finger-printing methods and hybridization to produce a 1.7-Mb overlapping clone map covering the TSC1 candidate region, with a single gap of 20 kb. We have localized 12 previously cloned genes and 17 genetic markers on this map and have confirmed the order of the genetic map. This deep set of overlapping clones is now ready to be used for candidate gene isolation, for transcription studies, or for sequencing.

Chromosome Mapping↗

Mutations in the human Jagged1 gene are responsible for Alagille syndrome.

Alagille syndrome (AGS) is an autosomal-dominant disorder characterized by intrahepatic cholestasis and abnormalities of heart, eye and vertebrae, as well as a characteristic facial appearance. Identification of rare AGS patients with cytogenetic deletions has allowed mapping of the gene of 20p12. We have generated a cloned contig of the critical region and used fluorescent in situ hybridization on cells from patients with submicroscopic deletions to narrow the candidate region to only 250 kb. Within this region we identified JAG1, the human homologue of rat Jagged1, which encodes a ligand for the Notch receptor. Cell-cell Jagged/Notch interactions are known to be critical for determination of cell fates in early development, making this an attractive candidate gene for a developmental disorder in humans. Determining the complete exon-intron structure of JAG1 allowed detailed mutational analysis of DNA samples from non-deletion AGS patients, revealing three frame-shift mutations, two splice donor mutations and one mutation abolishing RNA expression from the altered allele. We conclude that AGS is caused by haploinsufficiency of JAG1.

Alagille Syndrome↗

Assembly and analysis of cosmid contigs in the CEA-gene family region of human chromosome 19.

The carcinoembryonic antigen (CEA)-like genes are members of a large gene family which is part of the immunoglobulin superfamily. The CEA family is divided into two major subgroups, the CEA-subgroup and the pregnancy-specific glycoprotein (PSG)-subgroup. In the course of an effort to develop a set of overlapping cosmids spanning human chromosome 19, we identified 245 cosmids in a human chromosome 19 cosmid library (6-7X redundant) by hybridization with an IgC-like domain fragment of the CEA gene. A fluorescence-based restriction enzyme digest fingerprinting strategy was used to assemble 212 probe-positive cosmids, along with 115 additional cosmids from a collection of approximately 8,000 randomly selected cosmids, into five contigs. Two of the contigs contain CEA-subgroup genes while the remaining three contigs contain PSG-subgroup genes. These five contigs range in size from 100 kb to over 300 kb and span an estimated 1 Mb. The CEA-like gene family was determined by fluorescence in situ hybridization to map in the q13.1-q13.2 region of human chromosome 19. Analysis of the two CEA-subgroup contigs provided verification of the contig assembly strategy and insight into the organization of 9 CEA-subgroup genes.

Carcinoembryonic Antigen↗

Fine mapping of 12 previously unassigned EST clones to individual YACs in the familial Alzheimer's disease (FAD) region of chromosome 14q24.3.

We have constructed an approximately 4-Mb YAC contig spanning the microsatellite markers D14S1028-D14S61 on chromosome 14q24.3 using oligonucleotide primers to microsatellite markers, ESTs and the genes PSEN1, FOS, TGFB3 and UBE2L1. This contig consists of 44 ICI YACs and 5 megaCEPH YACs. The data reported here should aid the final construction of an integrated map of chromosome 14 and allow the identification and accurate mapping of additional novel ESTs within this region.

Alzheimer Disease↗

A human chromosome 7 yeast artificial chromosome (YAC) resource: construction, characterization, and screening.

The paradigm of sequence-tagged site (STS)-content mapping involves the systematic assignment of STSs to individual cloned DNA segments. To date, yeast artificial chromosomes (YACs) represent the most commonly employed cloning system for constructing STS maps of large genomic intervals, such as whole human chromosomes. For developing a complete YAC-based STS-content map of human chromosome 7, we wished to utilize a limited set of YAC clones that were highly enriched for chromosome 7 DNA. Toward that end, we have assembled a human chromosome 7 YAC resource that consists of three major components: (1) a newly constructed library derived from a human-hamster hybrid cell line containing chromosome 7 as its only human DNA; (2) a chromosome 7-enriched sublibrary derived from the CEPH mega-YAC collection by Alu-polymerase chain reaction (Alu-PCR)-based hybridization; and (3) a set of YACs isolated from several total genomic libraries by screening for > 125 chromosome 7 STSs. In particular, the hybrid cell line-derived YACs, which comprise the majority of the clones in the resource, have a relatively low chimera frequency (10-20%) based on mapping isolated insert ends to panels of human-hamster hybrid cell lines and analyzing individual clones by fluorescence in situ hybridization. An efficient strategy for polymerase chain reaction (PCR)-based screening of this YAC resource, which totals 4190 clones, has been developed and utilized to identify corresponding YACs for > 600 STSs. The results of this initial screening effort indicate that the human chromosome 7 YAC resource provides an average of 6.9 positive clones per STS, a level of redundancy that should support the assembly of large YAC contigs and the construction of a high-resolution STS-content map of the chromosome.

Animals↗

Isolation of the human Xp21 glycerol kinase gene by positional cloning.

The gene for human glycerol kinase deficiency (GK) maps in Xp21.3 in a critical region of about 50-250 kb located distal to the Duchenne muscular dystrophy gene (DMD) by analysis of patient deletions and YAC contigs. We have used a genomic exon amplification strategy to isolate potential exons from two cosmids which mapped to this interval. The genomic exons were used to isolate six overlapping cDNA clones from human fetal liver which encode the X-linked glycerol kinase gene. The cDNA clones map to cosmids, YAC clones and deletions in patients which define the GK critical region and also hybridize to several autosomal fragments and one Xq fragment in genomic DNA. The GK gene is expressed most in human liver with three transcript sizes of 1.85, 2.7, and 3.7 kb. Sequence analysis of 1.5 kb of several overlapping liver cDNA clones predicted a protein with approximately 63% similarity to the E. coli and B. subtilis glycerol kinase genes. The liver cDNA clones have sequence identity with four genomic exons and the 3' untranslated region from an Xp21.3 cosmid thus indicating that this is the expressed GK gene which when deleted in patients gives rises to GK deficiency.

Amino Acid Sequence↗

A 1.5-Mb cosmid contig of the CMT1A duplication/HNPP deletion critical region in 17p11.2-p12.

Charcot-Marie-Tooth disease type 1A (CMT1A) is associated with a 1. 5-Mb tandem duplication in chromosome 17p11.2-p12, and hereditary neuropathy with liability to pressure palsies (HNPP) is associated with a 1.5-Mb deletion at this locus. Both diseases appear to result from an altered copy number of the peripheral myelin protein-22 gene, PMP22, which maps within the critical region. To identify additional genes and characterize chromosomal elements, a 1.5-Mb cosmid contig of the CMT1A duplication/HNPP deletion critical region was assembled using a yeast artificial chromosome (YAC)-based isolation and binning strategy. Whole YAC probes were used for screening a high-density arrayed chromosome 17-specific cosmid library. Selected cosmids were spotted on dot blots and assigned to bins defined by YACs. This binning of cosmids facilitated the subsequent fingerprint analysis. The 1.5-Mb region was covered by 137 cosmids with a minimum overlap set of 52 cosmids assigned to 17 bins and 9 contigs.

Charcot-Marie-Tooth Disease↗

Detection of a megabase deletion in a patient with branchio-oto-renal syndrome (BOR) and tricho-rhino-phalangeal syndrome (TRPS): implications for mapping and cloning the BOR gene.

Genetic linkage analysis has previously mapped the locus for the autosomal dominant disorder branchio-oto-renal syndrome (BOR) to the pericentric region of chromosome 8q. A YAC contig spanning the putative BOR region, from D8S543 to D8S541, was constructed and confirmed by sequence-tagged site content mapping using microsatellite markers and by DNA hybridization analysis. YACs spanning the BOR interval were used as fluorescence in situ hybridization probes on a cell line from a patient with BO and tricho-rhino-phalangeal syndrome I that involves a chromosome 8q rearrangement. In addition to the cytogenetically defined direct insertion of material from 8q13.3-q21.13 into 8q24.11, a previously unidentified deletion of just under one megabase was found in 8q13.3. These data narrowed the most likely location of the BOR gene to a region corresponding to the proximal two-thirds of YAC 869E10 between D8S543 and D8S279.

Abnormalities, Multiple↗

Physical mapping of receptor type protein tyrosine phosphatase sigma (PTPRS) to human chromosome 19p13.3.

Receptor type protein tyrosine phosphatase sigma (PTPRS), a member of a subfamily of receptor type protein tyrosine phosphatases, has been mapped to human chromosome 19p13.3 using fluorescence in situ hybridization (FISH) analysis. Hybridization analysis of chromosome 19 library cosmids has revealed several positive clones that are part of a contig located in the same region. The location of this contig was verified since one of the cosmid clones is anchored to a high-resolution FISH map of human chromosome 19p. In addition, the location of this gene relative to previously mapped proximal markers reveals a new point in the human-mouse synteny map by extending the mouse chromosome 17 synteny region in the telomeric direction.

Animals↗

Isolation of an 800 kb contiguous DNA fragment encompassing a 3.5-cM region of chromosome 1 in Arabidopsis using YAC clones.

The apetala1 mutation of Arabidopsis affects floral meristem identity and the development of sepal and petal primordia of the flower. We mapped the available RFLP markers on chromosome 1 that are in the general vicinity of apetala1 on a fine structure map and then chose the closest RFLP as a starting point for contiguous DNA (contig) generation. We report here a contig of about 800 kilobases (kb) that spans a 3.5 cM region of chromosome 1. We used genomic libraries of Arabidopsis prepared in yeast artificial chromosome (YAC) vectors and the detailed characterization of 19 YACs is reported. RFLPs displayed by the end fragments from the walk were mapped to align and correlate the genetic and physical maps for this region of chromosome 1. In this segment of the genome, 1 cM corresponds to a little over 200 kb of physical distance.

Arabidopsis↗

A contiguous clone map over 3 Mb on the long arm of chromosome 11 across a balanced translocation associated with schizophrenia.

Forty-nine clones derived by microdissection of a schizophrenia-associated t(1;11)(q42.1;q14.3) breakpoint region have been assigned by somatic cell hybrid mapping to seven discrete intervals on the long arm of human chromosome 11. Eleven of the clones were shown to map to a small region immediately distal to the translocation breakpoint on 11q. A 3-Mb contiguous clone map of this region was established by isolation of corresponding YAC recombinants. The contig was oriented and shown to traverse the translocation breakpoint by FISH and microsatellite marker analysis. This contig will facilitate the isolation of candidate sequences whose expression may be affected by the translocation.

Base Sequence↗

The over-representation of binary DNA tracts in seven sequenced chromosomes.

BACKGROUND: DNA tracts composed of only two bases are possible in six combinations: A+G (purines, R), C+T (pyrimidines, Y), G+T (Keto, K), A+C (Imino, M), A+T (Weak, W) and G+C (Strong, S). It is long known that all-pyrimidine tracts, complemented by all-purines tracts ("R.Y tracts"), are excessively present in analyzed DNA. We have previously shown that R.Y tracts are in vast excess in yeast promoters, and brought evidence for their role in gene regulation. Here we report the systematic mapping of all six binary combinations on the level of complete sequenced chromosomes, as well as in their different subregions. RESULTS: DNA tracts composed of the above binary base combinations have been mapped in seven sequenced chromosomes: Human chromosomes 21 and 22 (the major contigs); Drosophila melanogaster chr. 2R; Caenorhabditis elegans chr. I; Arabidopsis thaliana chr. II; Saccharomyces cerevisiae chr. IV and M. jannaschii. A huge over-representation, reaching million-folds, has been found for very long tracts of all binary motifs except S, in each of the seven organisms. Long R.Y tracts are the most excessive, except in D. melanogaster, where the K.M motif predominates. S (G, C rich) tracts are in excess mainly in CpG islands; the W motif predominates in bacteria. Many excessively long W tracts are nevertheless found also in the archeon and in the eukaryotes. The survey of complete chromosomes enables us, for the first time, to map systematically the intergenic regions. In human and other chromosomes we find the highest over-representation of the binary DNA tracts in the intergenic regions. These over-representations are only partly explainable by the presence of interspersed elements. CONCLUSIONS: The over-representation of long DNA tracts composed of five of the above motifs is the largest deviation from randomness so far established for DNA, and this in a wide range of eukaryotic and archeal chromosomes. A propensity for ready DNA unwinding is proposed as the functional role, explaining the evolutionary conservation of the huge excesses observed.

Animals↗

Ordered YAC clone contigs assigned to rice chromosomes 3 and 11.

Yeast artificial chromosome (YAC) clones were arranged on the positions of restriction fragment length polymorphism (RFLP) and sequence-tagged site (STS) markers already mapped on the high-resolution genetic maps of rice chromosomes 3 and 11. From a total of 416 and 242 YAC clones selected by colony/Southern hybridization and polymerase chain reaction (PCR) analysis, 238 and 135 YAC clones were located on chromosomes 3 and 11, respectively. For chromosomes 3 and 11, 24 YAC contigs and islands with total coverage of about 46% and 12 contigs and islands with coverage of about 40%, respectively, were assigned. Although many DNA fragments of multiple copy marker sequences could not be mapped to their original locations on the genetic map by Southern hybridization because of a lack of RFLP, the physical mapping of YAC clones could often assign specific locations of such multiple copy sequences on the genome. The information provided here on contig formation and similar sequence distribution revealed by ordering YAC clones will help to unravel the genome organization of rice as well as being useful in isolation of genes by map-based cloning.

Blotting, Southern↗

Identification of a 1.1-Mb region for a carcass weight QTL onbovine Chromosome 14.

We previously mapped a quantitative trait locus for carcass weight, designated Carcass Weight-1 (CW-1), to bovine Chromosome 14 using a purebred Wagyu pedigree based on progeny design analysis. To refine the critical region within 8.1 cM flanked by microsatellites BMS1941 and INRA094, we constructed a bacterial artificial chromosome (BAC) contig composed of 60 tiled BAC clones and prepared a high-density physical map including 80 microsatellites, of which 55 were developed in this study. We conducted linkage disequilibrium (LD) mapping in the CW-1 region with 47 microsatellites using paternal half-sib pedigrees whose sires exhibited homozygous CW-1 Q alleles in the region. The LD mapping study significantly narrowed the CW-1 locus to the 1.1-Mb region between microsatellites DIK7012 and DIK7020. Finally, we surveyed the 1.1-Mb-region genotypes of 1700 steers from 11 bulls having -/-, Q/-, or Q/Q alleles in the region, and we examined the effect of the CW-1 Q allele on carcass weight. The presence of the first Q increased carcass weight by 23.6 kg (95% confidence interval [CI], 17.6-29.5 kg), and the second Q increased carcass weight an additional 15.2 kg (95% CI, 10.7-19.7 kg). These results indicate the presence of a gene responsible for carcass weight within the 1.1-Mb region.

Animals↗

Physical and meiotic mapping of the region of human chromosome 4q11-q13 encompassing the vitamin D binding protein DBP/Gc-globulin and albumin multigene cluster.

The vitamin D binding protein/Gc-globulin (DBP) gene is a member of a multigene cluster that includes albumin (ALB), alpha-fetoprotein (AFP), and alpha-albumin/afamin (AFM). All four genes have structural and functional similarities and map to the same chromosomal regions in humans (4q11-q13), mice, and rats. An accurate physical map of the region encompassing these genes is a prerequisite for study of their respective transcriptional regulation and identification of potential shared regulatory elements. By refining the physical and meiotic maps of the 4q11-q13 region and creating a local PAC contig, the order and transcriptional orientations of these four genes were determined to be centromere-3'-DBP-5'-5'-ALB-3'-5'-AFP-3'-5'-AFM3'-telomere. The ancestral DBP gene was separated from the ALB gene by >1.5 Mb. This organization and spacing establishes a foundation for ongoing functional studies in this region.

Albumins↗

YAC and cosmid contigs encompassing the Fukuyama-type congenital muscular dystrophy (FCMD) candidate region on 9q31.

Fukuyama-type congenital muscular dystrophy (FCMD), the second most common form of childhood muscular dystrophy in Japan, is an autosomal recessive severe muscular dystrophy associated with an anomaly of the brain. We had mapped the FCMD gene to an approximately 5-cM interval between D9S127 and D9S2111 on 9q31-q33 and had also found evidence for linkage disequilibrium between FCMD and D9S306 in this candidate region. Through further analysis, we have defined another marker, D9S172, which showed stronger linkage disequilibrium than D9S306. A yeast artificial chromosome (YAC) contig spanning 3,5 Mb, which includes this D9S306-D9S172 interval on 9q31, has been constructed by a combination of sequence-tagged site, Alu-PCR, and restriction mapping. Also, cosmid clones subcloned from the YAC were assembled into three contigs, one of which contains D9S2107, which showed the strongest linkage disequilibrium with FCMD. These contigs also allowed us to order the markers as follows: cen-D9S127-(approximately 800 kb)-D9S306 (identical to D9S53)-(approximately 700 kb)-A107XF9-(approximately 500 kb)-D9S172-(approximately 30 kb)-D9S299 (identical to D9S774)-(approximately 120 kb)-WI2269-tel. Thus, we have constructed the first high-resolution physical map of the FCMD candidate region. The YAC and cosmid contigs established here will be a crucial resource for identification of the FCMD gene and other genes in this region.

Chromosomes, Artificial, Yeast↗