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H Lehrach

Publications and source records attributed to H Lehrach.

At least 19 recordsLinked to original sources
PubMed1992

Gene database for the fission yeast Schizosaccharomyces pombe.

As an aid to the fission yeast genome project, we describe a database for Schizosaccharomyces pombe consisting of both genetic and physical information. As presented, it is therefore both an updated gene list of all the nuclear genes of the fission yeast, and provides an estimate of the physical distance between two mapped genes. Additionally, a field indicates whether the sequence of the gene is available. Currently, sequence information is available for 135 of the 501 known genes.

Databases, Factual↗
PubMed1992

Hybridization fingerprinting of high-density cDNA-library arrays with cDNA pools derived from whole tissues.

As part of an integrated mapping and sequencing analysis of genomes, we have developed an approach allowing the characterization of large numbers of cDNA library clones with a minimal number of experiments. Three basic elements used in the analysis of cDNA libraries are responsible for the high efficiency of this new approach: (1) high-density library arrays allowing thousands of clones to be screened simultaneously; (2) hybridization fingerprinting techniques to identify clones abundantly expressed in specific tissues (by hybridizations with labeled tissue cDNA pools) and to avoid the repeated selection of identical clones and of clones containing noncoding inserts; and (3) a computerized system for the evaluation of hybridization data. To demonstrate the feasibility of this approach, we hybridized high-density cDNA library arrays of human fetal brain and embryonal Drosophila with radiolabeled cDNA pools derived from whole mouse tissues. Fingerprints of the library arrays were generated, localizing clones containing cDNA sequences from mRNAs expressed at middle to high abundance (> 0.1-0.15%) in the respective tissue. Partial sequencing data from a number of clones abundantly expressed in several tissues were generated to demonstrate the value of the approach, especially for the selection of cDNA clones for the analyses of genomes based on expressed sequence tagged sites. Data obtained by the technique described will ultimately be correlated with additional transcriptional and sequence information for the same library clones and with genomic mapping information in a relational database.

Animals↗
PubMed1992

Radiation hybrid map spanning the Huntington disease gene region of chromosome 4.

Radiation hybrid (RH) mapping was used to construct a map of 11 markers in the distal 4 Mb of the short arm of chromosome 4, the region containing the Huntington disease gene. Two different methods for deriving the order of the markers were compared and both arrived at the same order as being the most likely. This order is also consistent with both the physical map constructed using pulsed-field gel electrophoresis (PFGE) and the meiotic linkage map. Comparing the RH map to the map determined by PFGE provided the means to equate RH map units (centirays) with actual physical distance in kilobases of DNA. In addition, a simple procedure for reducing the complexity of human DNA in radiation hybrids is described. One cell line isolated using this procedure contains, as its only human DNA, approximately 2 Mb surrounding the Huntington disease gene.

Chromosome Mapping↗
PubMed1992

A yeast artificial chromosome contig containing the complete Duchenne muscular dystrophy gene.

A contig of 36 overlapping yeast artificial chromosome (YAC) clones has been constructed for the complete Duchenne muscular dystrophy (DMD) gene in Xp21. The YACs were isolated from a human 48,XXXX YAC library using the DMD cDNA and brain promoter fragments as hybridization probes. The YAC clones were characterized for exon content using HindIII or EcoRI digests, hybridization of individual DMD cDNA probes, and polymerase chain reaction (PCR) amplification of specific exons near the 5' end of the gene. For comparison to the known long-range restriction map of the DMD gene, YAC clones were digested with SfiI and hybridized with DMD cDNA probes. The combined analysis of the exon content and the SfiI map allowed an approximately 3.2-Mb YAC contig to be constructed. The complete 2.4-Mb DMD gene could be represented in a minimum set of 7 overlapping YAC clones.

Chromosomes, Fungal↗
PubMed1992

Chromosomal assignment of human YAC clones by fluorescence in situ hybridization: use of single-yeast-colony PCR and multiple labeling.

Alu-PCR provides a convenient tool for amplification of human-specific sequences from yeast DNA containing yeast artificial chromosomes (YAC) clones. PCR products can be labeled nonisotopically and hybridized in situ, and the chromosomal origin of the clones can be determined. This avoids time-consuming gel purification of the yeast artificial chromosome and the low-efficiency procedure of labeling whole yeast DNA containing the YAC. The application of Alu-PCR to single-yeast colonies permits the mapping of YACs at a very early stage of their characterization. In situ hybridization can detect clones with noncontiguous fragments of DNA, and these can be discarded without further time-consuming characterization. To increase further the potential of the method, we show the application of multicolor hybridization techniques.

Base Sequence↗
PubMed1992

Complete coverage of the Schizosaccharomyces pombe genome in yeast artificial chromosomes.

The genome of the fission yeast, Schizosaccharomyces pombe, consists of some 14 million base pairs of DNA contained in three chromosomes. On account of its excellent genetics we used it as a test system for a strategy designed to map mammalian chromosomes and genomes. Data obtained from hybridization fingerprinting established an ordered library of 1,248 yeast artificial chromosome clones with an average size of 535 kilobases. The clones fall into three contigs completely representing the three chromosomes of the organism. This work provides a high resolution physical and clone map of the genome, which has been related to available genetic and physical map information.

Base Composition↗
PubMed1992

A strategy for the selection of transcribed sequences in the Xq28 region.

As an essential step towards an exhaustive analysis of the coding potential of large regions of the genome, we have developed a protocol allowing the rapid isolation of transcripts defined by overlapping clone libraries. The method is based on the hybridisation of cDNA inserts, which had been amplified by PCR from cDNA libraries, to biotinylated DNA from cosmids or cosmid pools. Nonspecific hybrids are then removed, the selected cDNAs are eluted and reamplified by PCR. Using a cosmid containing part of the FMR-1 gene as test, we were able to demonstrate an eighty thousand fold enrichment of cDNAs for this gene after two rounds of selection-amplification. The technique was applied to the analysis of transcripts from two cosmid contigs, together encompassing a region of 900 kb in Xq28. These experiments have thus far resulted in the identification of 81 cDNA clones, of which 54 clones were mapped back to the cosmid contigs. Of the 54 clones placed on the contig maps, 12 cDNA clones can be shown to belong to two genes which have been previously reported (L1CAM and QM).

Base Sequence↗
PubMed1992

Localization of the synovial sarcoma t(X;18)(p11.2;q11.2) breakpoint by fluorescence in situ hybridization.

A high proportion of synovial sarcomas contain a chromosome translocation t(X;18)(p11.2;q11.2). We have previously used somatic cell hybrids derived from an established cell line, SS255, to map the X chromosome breakpoint to the interval flanked by the markers DXS14 and DXS146. In this study we have examined these hybrids with thirteen additional markers located at Xp11.3-Xcen, by Southern hybridization. Based on these results we have delimited the breakpoint as follows Xpter-DXS228-(UBE1-OATL1-TIMP-DXS226 )-(DXS255-TFE3-ELK1-DXS146)-OATL2- X;18-(DXS14-DXS422-DXS423-DXS674-DXS679)-+ ++Xcen. Confirmation of the breakpoint location has been obtained by analysis of two synovial sarcoma cell lines, SS255 and HA2243, using fluorescence in situ hybridization. A 350kb YAC probe spanning the DXS423 locus hybridized only to the derivative X chromosome, showing that it maps proximal to the breakpoint. Two YAC probes of 300kb and 450kb, containing the OATL2 locus, hybridized to both derivative chromosomes, indicating that these YACs span the translocation breakpoint. Similar results were obtained with both cell lines. The identification of YACs that span the t(X;18) breakpoint now facilitates a strategy for cloning candidate genes from this precisely defined region.

Animals↗
PubMed1992

Isolation of new probes from Xq12-->q13: an example of the screening of reference libraries with Alu-PCR products from radiation hybrids.

In order to isolate new probes from the juxtacentromeric region of the long arm of the human X chromosome, we used Alu-mediated polymerase chain reaction (Alu-PCR) products as probes to directly screen a chromosome X-specific gridded cosmid library. These Alu-PCR products were synthesized from radiation hybrids containing the loci DXS159, PGK1, and PGK1P1. This approach allowed us to select 18 cosmids capable of hybridizing with at least two Alu-PCR products. Four cosmids hybridized to more than three Alu-PCR products. Three of these four cosmids were contiguous, and the fourth was independent. Two cosmids that hybridized with two Alu-PCR products were further characterized. Physical mapping indicated that all of these clones are located in the expected region on Xq, confirming the validity of our approach.

Base Sequence↗
PubMed1992

Fine mapping of the McLeod locus (XK) to a 150-380-kb region in Xp21.

McLeod syndrome, characterized by acanthocytosis and the absence of a red-blood-cell Kell antigen (Kx), is a multisystem disorder involving a late-onset myopathy, splenomegaly, and neurological defects. The locus for this syndrome has been mapped, by deletion analysis, to a region between the loci for Duchenne muscular dystrophy (DMD) and chronic granulomatous disease (CGD). In this study, we describe a new marker, 3BH/R 0.3 (DXS 709), isolated by cloning the deletion breakpoint of a DMD patient. A long-range restriction map of Xp21, encompassing the gene loci for McLeod and CGD, was constructed, and multiple CpG islands were found clustered in a 700-kb region. Using the new marker, we have limited the McLeod syndrome critical region to 150-380-kb. Within this interval, two CpG-rich islands which may represent candidate sites for the McLeod gene were identified.

Blotting, Southern↗
PubMed1991

W (A or T) sequences as probes and primers suitable for genomic mapping and fingerprinting.

A limitation to the use of oligonucleotide probes as tools for genetic and physical mapping has been the low hybridization positive frequency obtained by oligonucleotides of sufficient length to hybridize preferentially to cloned insert DNA (and not host E. coli genomic DNA). Both computer and experimental results now indicate that oligonucleotide probes composed of W (A or T) sequence are preferentially found in eukaryotic DNA, and can be used to provide high frequency, discriminative hybridization. Such W sequences may be useful as either probes or PCR primers in molecular diagnostic applications as well as in genetic and physical mapping.

Adenine↗
PubMed1991

Physical map of human Xq27-qter: localizing the region of the fragile X mutation.

We describe a physical map of the end of the long arm of the human X chromosome encompassing the region from Xq27.2 to the q telomere, inclusive of the chromosomal band Xq28. This region is of particular interest, since it contains the highest density of genes associated with genetic diseases. The map covers a total of 12 megabases (Mb) of DNA and extends from the telomere to 3 Mb beyond the most likely position of the fragile X mutation, defined by a cluster of translocation breakpoints in somatic cell hybrids. The map determines order and position of loci throughout the Xq28 region and localizes cell line breakpoints marking the fragile X region to an interval of 300-700 kilobases between 8 and 8.7 Mb proximal of the Xq telomere.

Blotting, Southern↗
PubMed1991

A novel and rapid method for isolating sequences adjacent to rare cutting sites and their use in physical mapping.

We describe a simple PCR based technique which can be used to isolate sequences adjacent to rare cutter sites and can subsequently be employed for the construction of long range physical maps. The method involves the ligation of an adaptor to rare cutter sequences and its use as a target for forward priming in PCR. Primers to Alu repeat elements initiate synthesis of the reverse strand. Using this technique any rare cutter site which has a repeat element within amplification range can be cloned. We have isolated six unique sequences around NotI sites from an irradiation reduced hybrid containing a fragment of human chromosome 22 and are using these for physical mapping around the Ewing's sarcoma translocation breakpoint on chromosome 22.

Base Sequence↗
PubMed1991

Use of high coverage reference libraries of Drosophila melanogaster for relational data analysis. A step towards mapping and sequencing of the genome.

Three differently made, primary Drosophila cosmid libraries of 16-fold genome coverage have been generated. Also, a jumping library has been created by a new method that takes advantage of methylation differences between genomic DNA and vector. Thirdly, two cDNA libraries have been picked. All these libraries have been arrayed on high-density in situ filters, each containing 9216 clones. As a reference system, such filters are distributed and identified clones are provided. Single-copy probes have identified on average 1.4 cosmids per genome equivalent. Together with cytogenetically mapped yeast artificial chromosomes, the libraries are also being used for physically mapping the genome, mainly by oligonucleotide fingerprinting and pool hybridizations. cDNA clones are further examined by a partial sequencing analysis by oligomer hybridization.

Animals↗
PubMed1991

Mapping irradiation hybrids to cosmid and yeast artificial chromosome libraries by direct hybridization of Alu-PCR products.

A direct hybridization protocol is described for screening cosmid and yeast artificial chromosome libraries with pools of Alu-PCR products from somatic cell or irradiation hybrids. This method eliminates purification, cloning and analysis of each individual Alu-PCR product before library screening. A series of human X chromosome irradiation hybrids were mapped by this method, using a cosmid reference library for comparisons between overlapping hybrids to identify interesting clones for further analysis.

Base Sequence↗
PubMed1991

Yeast artificial chromosome libraries containing large inserts from mouse and human DNA.

Yeast artificial chromosome (YAC) libraries have been difficult to construct with average insert sizes greater than 400 kilobase pairs when DNA is size-fractionated in low-melting-point agarose. By using yeast chromosome in mock cloning experiments, we found that polyamines should be present whenever agarose containing high molecular weight DNA is melted to protect DNA from degradation. By incorporating polyamines during the cloning procedure, we constructed YAC libraries from mouse and human DNA with average insert sizes of 700 and 620 kilobase pairs, respectively. Several genome equivalents of these YAC libraries were replicated onto the surface of many duplicate agar plates using a 40,000 multipin transfer device. High-density filter replicas were screened by hybridization, and 70 mouse YAC clones from 31 loci and 132 human YAC clones from 49 loci were isolated.

Animals↗