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Genetic and physical mapping of a gene encoding a methyl CpG binding protein, Mecp2, to the mouse X chromosome.

The methyl CpG binding proteins (MeCP1 and MeCP2) are a class of proteins that bind to templates containing symmetrically methylated CpGs. Using an interspecific backcross segregating a number of X-linked markers, we have localized the Mecp2 gene in mouse to the X chromosome close to the microsatellite marker DXMit1. Detailed physical mapping utilizing an available YAC contig encompassing the DXMit1 locus has localized the Mecp2 gene to a 40-kb region between the L1cam and the Rsvp loci, indicating the probable position of a homologue on the human X chromosome.

Animals↗

Construction of a high-resolution 2.5-Mb transcript map of the human 6p21.2-6p21.3 region immediately centromeric of the major histocompatibility complex.

We have constructed a 2.5-Mb physical and transcription map that spans the human 6p21.2-6p21.3 region and includes the centromeric end of the MHC, using a combination of techniques. In total 88 transcription units including exons, cDNAs, and cDNA contigs were characterized and 60 were confidently positioned on the physical map. These include a number of genes encoding nuclear and splicing factors (Ndr kinase, HSU09564, HSRP20); cell cycle, DNA packaging, and apoptosis related [p21, HMGI(Y), BAK]; immune response (CSBP, SAPK4); transcription activators and zinc finger-containing genes (TEF-5, ZNF76); embryogenesis related (Csa-19); cell signaling (DIPP); structural (HSET), and other genes (TULP1, HSPRARD, DEF-6, EO6811, cyclophilin), as well as a number of RP genes and pseudogenes (RPS10, RPS12-like, RPL12-like, RPL35-like). Furthermore, several novel genes (a Br140-like, a G2S-like, a FBN2-like, a ZNF-like, and B1/KIAA0229) have been identified, as well as cDNAs and cDNA contigs. The detailed map of the gene content of this chromosomal segment provides a number of candidate genes, which may be involved in several biological processes that have been associated with this region, such as spermatogenesis, development, embryogenesis, and neoplasia. The data provide useful tools for synteny studies between mice and humans, for genome structure analysis, gene density comparisons, and studies of nucleotide composition, of different isochores and Giemsa light and Giemsa dark bands.

Amino Acid Sequence↗

Genomic organization and mapping of the human and mouse neuronal beta2-nicotinic acetylcholine receptor genes.

As a first step in determining whether there are polymorphisms in the nicotinic acetylcholine receptor (nAChR) genes that are associated with nicotine addiction, we isolated genomic clones of the beta2-nAChR genes from human and mouse BAC libraries. Although cDNA sequences were available for the human gene, only the promoter sequence had been reported for the mouse gene. We determined the genomic structures by sequencing 12 kb of the human gene and over 7 kb of the mouse gene. While the sizes of exons in the mouse and human genes are the same, the introns differ in size. Both promoters have a high GC content (60-80%) proximal to the AUG and share a neural-restrictive silencer element (NRSE), but overall sequence identity is only 72%. Using a 6-Mb YAC contig of Chr 1, we mapped the human beta2-nAChR gene, CHRNB2, to 1q21.3 with the order of markers cen, FLG, IVL, LOR, CHRNB2, tel. The mouse gene, Acrb2, had previously been mapped to Chr 3 in a region orthologous to human Chr 1. We refined mapping of the mouse gene and other markers on a radiation hybrid panel of Chr 3 and found the order cen, Acrb2, Lor, Iv1, Flg, tel. Our results indicate that this cluster of markers on human Chr 1 is inverted with respect to its orientation on the chromosome compared with markers in the orthologous region of mouse Chr 3.

Amino Acid Sequence↗

Chromosomal heteromorphism and an apparent translocation detected using a BAC contig spanning the mating type locus of Phytophthora infestans.

Genetic and physical irregularities associated with the mating type locus of the oomycete, Phytophthora infestans, were revealed by analyzing a contig spanning the locus that was constructed using a bacterial artificial chromosome library. Contigs from both homologs of an A1 strain A/a genotype at mating type locus) had chromosome-specific differences, flanked by regions of similarity. Such heteromorphism was detected within multiple isolates. The mating type locus was narrowed to a 60-70kb interval by genetic mapping of candidate genes, identified using a cDNA library. During these analyses, an unusual isolate of P. infestans was identified in which the mating type determinant had apparently translocated from its location in typical strains. Comparative mapping of the cDNAs between P. infestans and P. parasitica revealed partial synteny between the species however; substantial rearrangements existed and no cDNA was tightly linked to mating type in P. parasitica. These findings add to previous observations of unusual genetic behavior involving mating type in Phytophthora.

Chromosome Mapping↗

A 1.5-megabase yeast artificial chromosome contig from human chromosome 10q11.2 connecting three genetic loci (RET, D10S94, and D10S102) closely linked to the MEN2A locus.

The genetic loci RET, D10S94, and D10S102 from human chromosome 10q11.2 are very closely linked to a locus responsible for the multiple endocrine neoplasia type 2 (MEN2A and MEN2B) and medullary thyroid carcinoma (MTC1) familial cancer syndromes. We have constructed a 1.5-megabase contig consisting of six genomic yeast artificial chromosome clones which include these loci and define their physical order. A critical crossover event has been identified within the map interval; this event places the MEN2A locus centromeric to D10S102 and defines the orientation of the physical map on the chromosome. The orientation of the contig and order of the markers are centromere-RET-D10S94-D10S102-telomere. In addition, a microsatellite repeat polymorphism with a heterozygosity of 71% at the RET locus and a restriction fragment length polymorphism with a heterozygosity of 42% detected by a lambda clone from the D10S94 locus have been developed for high-resolution genetic linkage mapping and predictive diagnostic testing. These data place three important markers on a contiguous physical map, narrow the MEN2 disease locus interval, and provide a framework for further candidate gene identification efforts. Placement of these genetic loci along a clone-based map and continued expansion of the contig will also facilitate efforts to determine the relationship of physical to genetic distance near the centromeres of human chromosomes.

Base Sequence↗

Structural analysis and physical mapping of a pericentromeric region of chromosome 5 of Arabidopsis thaliana.

The Arabidopsis thaliana CIC YAC 2D2, 510 kb long and containing a small block of 180 bp satellite units was subcloned after EcoR1 digestion in the pBluescript plasmid. One of these clones was mapped genetically in the pericentromeric region of chromosome 5. The analysis of 40 subclones of this YAC showed that they all contain repeated sequences with a high proportion of transposable elements. Three new retrotransposons, two Ty-3 Gypsy-like and one Ty-1 Copia, were identified in addition to two new tandem-repeat families. A physical map of the chromosome 5 pericentromeric region was established using CIC YAC clones, spanning around 1000 kb. This contig extends from the CIC YAC 9F5 and 7A2 positioned on the left arm of chromosome 5 to a 5S rDNA genes block localized by in-situ hybridization in the pericentromeric region. Hybridization of the subclones on the CIC YAC library showed that some of them are restricted to the pericentromeric region of chromosome 5 and represent specific markers of this region.

Amino Acid Sequence↗

Physical and genetic mapping of the macular corneal dystrophy locus on chromosome 16q and exclusion of TAT and LCAT as candidate genes.

PURPOSE: Macular corneal dystrophy (MCD) is an inherited autosomal recessive disorder that has been subdivided into three immunophenotypes, MCD types I, IA and II. We previously mapped the MCD type I gene to chromosome 16q22 and suggested that the MCD type II gene was linked to the same region. The purpose of this study was to construct a genomic contig spanning the MCD region and to narrow the MCD critical interval by haplotype analysis. The TAT and LCAT genes were mapped to determine if they might be the MCD gene. METHODS: The MCD contig was constructed by screening YAC, PAC, and BAC libraries with microsatellite, STS and EST markers, employing a systematic "DNA walking" technique. Polymorphic markers mapped and ordered on the contig were used to screen the MCD affected individuals and their family members for haplotype analysis. RESULTS: Twenty-two YAC, 30 PAC, and 17 BAC clones were mapped to form the MCD contig. Markers mapped on the contig include 19 microsatellite, 14 STS, and 15 EST markers. Moreover, 18 novel STS markers were generated. Using the mapped and ordered microsatellite markers, haplotype analysis on 21 individuals with MCD type I or type II and their family members from Iceland narrowed the MCD interval to 3 overlapping PAC clones. In addition, the TAT and LCAT genes were mapped outside the MCD region. CONCLUSIONS: We established a genomic contig for the MCD region and dramatically narrowed the MCD critical interval. Mapping data show that the TAT and LCAT genes are not the cause of MCD.

Contig Mapping↗

Narrowing the genetic interval and yeast artificial chromosome map in the branchio-oto-renal region on chromosome 8q.

Branchio-oto-renal (BOR) syndrome is an autosomal dominant disorder characterized by branchial abnormality, hearing loss, and renal anomalies. Recently, the disease gene has been localized to chromosome 8q. Here, we report genetic studies that further refine the disease gene region to a smaller interval and identify several YACs from the critical region. We studied two large, clinically well-characterized BOR families with a set of 13 polymorphic markers spanning the D8S165-D8S275 interval from the chromosome 8q region. Based on multipoint analysis, the highest likelihood for the location of the BOR gene is between markers D8S543 and D8S530, a distance of about 2 cM. YACs that map in the BOR critical region have been identified and characterized by fluorescence in situ hybridization and pulsed-field gel electrophoresis. A YAC contig, based on the STS content map, that covers a minimum of 4 Mb of human DNA in the critical region of BOR is assembled. This lays the groundwork for the construction of a transcriptional map of this region and the eventual identification of genes involved in BOR syndrome.

Abnormalities, Multiple↗

A new DNA sequence assembly program.

We describe the Genome Assembly Program (GAP), a new program for DNA sequence assembly. The program is suitable for large and small projects, a variety of strategies and can handle data from a range of sequencing instruments. It retains the useful components of our previous work, but includes many novel ideas and methods. Many of these methods have been made possible by the program's completely new, and highly interactive, graphical user interface. The program provides many visual clues to the current state of a sequencing project and allows users to interact in intuitive and graphical ways with their data. The program has tools to display and manipulate the various types of data that help to solve and check difficult assemblies, particularly those in repetitive genomes. We have introduced the following new displays: the Contig Selector, the Contig Comparator, the Template Display, the Restriction Enzyme Map and the Stop Codon Map. We have also made it possible to have any number of Contig Editors and Contig Joining Editors running simultaneously even on the same contig. The program also includes a new 'Directed Assembly' algorithm and routines for automatically detecting unfinished segments of sequence, to which it suggests experimental solutions.

Animals↗

AppaDB: an AcedB database for the nematode satellite organism Pristionchus pacificus.

Pristionchus pacificus is a free-living nematode of the Diplogastridae family and was recently developed as a satellite system in evolutionary developmental biology. AppaDB, a P.pacificus database, was created (http://appadb.eb.tuebingen. mpg.de) to integrate the genomic data of P.pacificus, comprising the physical map, genetic linkage map, EST and BAC end sequence and hybridization data. This developing database serves as a repository to search and find any information regarding physical contigs or genetic markers required for mapping of mutants. Additionally, it provides a platform for the Caenorhabditis elegans community to compare nematode genetic data in an evolutionary perspective.

Animals↗

Gene order is conserved within the human chromosome 21 linkage group on mouse chromosome 10.

One hundred progeny from each of two intersubspecific mouse backcrosses were used to construct a comparative genetic map of a region of mouse chromosome 10 (MMU10) that is homologous to the distal tip of the long arm of human chromosome 21 (HSA21). The analysis included five genes and three simple sequence repeat markers, two of which flanked the HSA21-homologous cluster on either side. Analysis of 200 backcross progeny detected at least one crossover between each pair of adjacent genes and demonstrated that the proximal to distal orientation of the cluster was reversed between human and mouse. The order was determined to be Fyn-1-D10Mit20-S100b-Col6a1-Itgb2-Pfkl+ ++/D10Mit7-D10Mit11. Comparative mapping supports the order of corresponding markers on HSA21 determined using pulsed-field gel electrophoresis and radiation hybrid line data. However, sequence tagged site content mapping of human yeast artificial chromosomes (YACs) yielded conflicting data on the relative positions of human COL6A1 and S100B on HSA21. This discrepancy was resolved here by demonstrating that several key YACs used in the human contig analysis were mistyped for S100B. The murine map reported here provides a scaffold for construction of physical maps and yeast artificial chromosome contigs that will be useful in the development of mouse models for the study of Down syndrome.

Animals↗

A 2.5-Mb contig constructed from Angus, Longhorn and horned Hereford DNA spanning the polled interval on bovine chromosome 1.

The polled locus has been mapped by genetic linkage analysis to the proximal region of bovine chromosome 1. As an intermediate step in our efforts to identify the polled locus and the underlying causative mutation for the polled phenotype, we have constructed a BAC-based physical map of the interval containing the polled locus. Clones containing genes and markers in the critical interval were isolated from the TAMBT (constructed from Angus and Longhorn genomic DNA) and CHORI-240 (constructed from horned Hereford genomic DNA) BAC libraries and ordered based on fingerprinting and the presence or absence of 80 STS markers. A single contig spanning 2.5 Mb was assembled. Comparison of the physical order of STSs to the corresponding region of human chromosome 21 revealed the same order of genes within the polled critical interval. This contig of overlapping BAC clones from horned and polled breeds is a useful resource for SNP discovery and characterization of positional candidate genes.

Animals↗

Radiation hybrid mapping of chromosomal region 2p15-p16: integration of expressed and polymorphic sequences maps at the Carney complex (CNC) and Doyne honeycomb retinal dystrophy (DHRD) loci.

Chromosomal region 2p15-p16, which corresponds to the genetic interval flanked by polymorphic markers D2S119 and D2S378 and covers a genetic distance of approximately 16 cM, is underrepresented in the existing maps of chromosome 2. This is primarily due to two large gaps of unknown physical distance within the known yeast and bacterial artificial chromosome (YAC and BAC, respectively) maps. In constructing a YAC/BAC contig covering 2p15-p16, a total of 55 sequence-tagged sites (25 of which are polymorphic), including new sequences derived from chromosomal walking, and 38 expressed sequence tags were screened by a commercially available RH panel (Stanford G3). A total of 45 of these sequences were placed; 32 of them were assigned at unique sites. The high-resolution TNG3 RH panel was then used to define further the chromosomal order of markers contained in the region flanked by D2S391 and D2S2153. This region harbors the genes for two autosomal dominant disorders, Carney complex (CNC), a multiple neoplasia syndrome, and Doyne honeycomb retinal dystrophy (DHRD), a disease leading to blindness at a young age. This is the first attempt to order cloned sequences in chromosomal region 2p15-p16, an area apparently resistant to YAC cloning. Construction of the 2p15-p16 RH map is critical for identifying the genes responsible for CNC and DHRD, as well as for the molecular elucidation of a chromosomal region that is frequently rearranged in tumors.

Chromosome Mapping↗

Integrated high-resolution BAC, P1, and transcript map of the CHH region in chromosome 9p13.

A bacterial artificial chromosome (BAC) and P1 contig of the proximal part of chromosome 9p centromeric of markers D9S165 and D9S304 is described. This 1.1- to 1.7-Mb portion of chromosome 9p13 was previously not physically mapped. It contains 24 genes or expressed sequence tags, five polymorphic AC repeats, and three new polymorphic single-strand conformation polymorphism variants. Several of the genes thus mapped are excellent candidates for disease-causing genes whose loci have previously been assigned to proximal 9p. Our primary interest is in the cartilage-hair hypoplasia gene (CHH) that resides within the contig between markers D9S163 and D9S1791 based on linkage evidence.

Base Sequence↗

Identification of a 1-Mb common region at 16q24.1-24.2 deleted in hepatocellular carcinoma.

To identify the location of one or more putative tumor suppressor genes that may be involved in hepatocellular carcinoma (HCC), we examined 96 such tumors for their patterns of allelic loss at 21 microsatellite marker loci distributed along chromosome arm 16q. Allelic loss at one or more loci was observed in 58 (60%) of these tumors. Detailed deletion mapping identified a distinct commonly deleted region located within an interval flanked by D16S534 and D16S3091 at 16q24.1-24.2. By constructing a physical map consisting of a YAC contig across the region, the extent of the deleted region was determined to be less than 1 Mb. Among the tumors for which clinical data were available, allelic loss at 16q24.1-24.2 was more frequent in tumors arising from liver cirrhosis compared to HCCs arising from chronic hepatitis (30/42, 71%, vs. 13/33, 39%; P = 0. 0054). Additionally, allelic loss at 16q24.1-24.2 was frequently observed in small tumors and early-stage tumors as well as in tumors of more advanced phenotype.

Carcinoma, Hepatocellular↗

A duplicated gene in the breakpoint regions of the 7q11.23 Williams-Beuren syndrome deletion encodes the initiator binding protein TFII-I and BAP-135, a phosphorylation target of BTK.

Williams-Beuren syndrome (WBS) is a neurodevelopmental disorder with multisystemic manifestations caused by heterozygosity for a partial deletion of chromosome band 7q11.23. The breakpoints cluster within regions located approximately 1 cM either side of the elastin (ELN) locus. We have characterized a duplicated region near the common deletion breakpoints, which includes a transcribed gene. The centromeric (C) and telomeric (T) copies are almost identical in the duplicated 3[prime] portions but diverge at their 5[prime]-ends. C-specific 4.3 kb mRNA and T-specific 5.4 kb mRNA are widely expressed in embryonic and adult tissues. The telomeric gene gives rise to several alternatively spliced forms and is deleted in all WBS individuals who have documented ELN deletions. Database searches revealed that this gene encodes BAP-135, a protein phosphorylated by Bruton's tyrosine kinase in B cells, as well as the multifunctional transcription factor TFII-I, hence the gene name GTF2I. The centromeric gene is not deleted in WBS and appears to be a partially truncated expressed pseudogene with no protein product (gene name GTF2IP1). Both loci map to different genomic clone contigs that also contain other deleted and non-deleted loci. A probe from the shared region recognizes a >3 Mb Not I junction fragment that is unique to individuals with the WBS deletion. Therefore, the duplicated region containing GTF2I and GTF2IP1 respectively is located close to the deletion breakpoints and may predispose to unequal meiotic recombination between chromosome 7 homologs and/or to intrachromosomal rearrangements. Hemizygosity for GTF2I may also contribute to the WBS phenotype.

Adult↗

Transcriptional map of the 2.5-Mb CBR-ERG region of chromosome 21 involved in Down syndrome.

The region of chromosome 21 between genes CBR and ERG (CBR-ERG region), which spans 2.5 Mb on 21q22.2, has been defined by analysis of patients with partial trisomy 21. It contributes significantly to the pathogenesis of many characteristics of Down syndrome, including morphological features, hypotonia, and mental retardation. Cosmid contigs covering 80% of the region were constructed and EcoRI maps produced. These cosmids were used for exon trapping and cDNA selection from three cDNA libraries (fetal brain, fetal liver, and adult skeletal muscle). Isolated exons and cDNAs were mapped on the EcoRI map, organized into contigs, sequenced, and used as probes for Northern blot analysis of RNA from fetal and adult tissues. We identified 27 genuine or highly probable transcriptional units evenly distributed along the CBR-ERG region. Eight of the transcriptional units are known genes.

Chromosome Mapping↗