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H Lehrach

Publications and source records attributed to H Lehrach.

At least 217 records · Page 12Linked to original sources
PubMed1993

Olfactory receptors: transduction, diversity, human psychophysics and genome analysis.

The emerging understanding of the molecular basis of olfactory mechanisms allows one to answer some long-standing questions regarding the complex recognition machinery involved. The ability of the olfactory system to detect chemicals at sub-nanomolar concentrations is explained by a plethora of amplification devices, including the coupling of receptors to second messenger generation through GTP-binding proteins. Specificity and selectivity may be understood in terms of a diverse repertoire of olfactory receptors of the seven-transmembrane-domain receptor superfamily, which are probably disposed on olfactory sensory neurons according to a clonal exclusion rule. Signal termination may be related to sets of biotransformation enzymes that process odorant molecules, as well as to receptor desensitization. Many of the underlying molecular components show specific expression in olfactory epithelium, with a well-orchestrated developmental sequence of emergence, possibly related to sensory neuronal function and connectivity requirements. A general model for molecular recognition in biological receptor repertoires allows a prediction of the number of olfactory receptors necessary to achieve efficient detection and sheds light on the analogy between the immune and olfactory systems. The molecular cloning and mapping of a human genomic olfactory receptor cluster on chromosome 17 provides insight into olfactory receptor diversity, polymorphism and evolution. Combined with future genotype-phenotype correlation, with particular reference to specific anosmia, as well as with computer-based molecular modelling, these studies may provide insight into the odorant specificity of olfactory receptors.

GTP-Binding Proteins↗
PubMed1993

Identification of a yeast artificial chromosome (YAC) spanning the synovial sarcoma-specific t(X;18)(p11.2;q11.2) breakpoint.

A somatic cell hybrid containing the synovial sarcoma-associated t(X;18)(p11.2;q11.2) derivative (der(X)) chromosome was used to characterize the translocation breakpoint region on the X chromosome. By using Southern hybridization of DNA from this der(X) hybrid in conjunction with Xp-region specific radiation reduced cell hybrids and probes, it was found that this breakpoint maps within the ornithine aminotransferase (OAT) L1 cluster. A yeast artificial chromosome (YAC) clone (OAT YAC2) which hybridizes to a human OAT cDNA probe and is known to contain part of the OATL1 cluster was selected and used to confirm these results both by fluorescence in situ hybridization on synovial sarcoma patient material and by hybridization of its end-clones to the der(X) containing hybrid cells. It was found that indeed the human Xp sequences contained within this YAC are split as a consequence of the (X;18) translocation. Therefore, we conclude that OAT YAC2 spans the synovial sarcoma-specific translocation breakpoint and, as such, may serve as an ideal starting point from which the gene(s) involved in the development of this soft tissue tumor can be isolated.

Animals↗
PubMed1993

Physical mapping and YAC contig analysis of the region surrounding Xist on the mouse X chromosome.

The Xist sequence has been proposed as a potential candidate for the X-inactivation center based both on its localization within the candidate region for the X-inactivation center in man and mouse and on its unique pattern of expression from the inactive X chromosome. We have cloned 550 kb of DNA surrounding the mouse Xist sequence in contiguously overlapping YAC clones and have developed a long-range restriction map that spans almost 1 Mb of this region and includes this YAC contig. The detailed restriction map we have established provides a framework for the identification of expressed sequences other than Xist that may equally exhibit unusual expression characteristics associated with X inactivation. The presence of possible structural or methylation differences within this region between the active and inactive X chromosomes has been investigated through comparative analysis of male and female genomic DNA, and we report here the identification of certain CpG-containing restriction sites around Xist that have an interesting differential methylation status on the inactive and active X chromosomes.

Animals↗
PubMed1993

The isolation of cDNAs from OATL1 at Xp 11.2 using a 480-kb YAC.

Using an ornithine-delta-aminotransferase (OAT) cDNA, we identified five YACs that cover two nonadjacent OAT-related loci in Xp11.2-p11.3, designated OATL1 (distal) and OATL2 (proximal). Because several retinal degenerative disorders map to this region, we used YAC2 (480 kb), which covers the most distal part of OATL1, as a probe to screen a retinal cDNA library. From 8 x 10(4) plaques screened, we isolated 13 clones. Two were OAT cDNAs. The remaining 11 were divided into eight groups by cross-hybridization. Groups 1-4 contain cDNAs that originate from single-copy X-linked genes in YAC2. Each has an open reading frame of > 500 bp and detects one or more transcripts on a Northern blot. The gene for each was sublocalized and ordered in YAC2. The cDNAs in groups 5-8 contained two or more Alu sequences, had no open reading frames, and did not detect transcripts. The cDNAs from groups 1-4 provide expressed sequence tags and identify candidate genes for the genetic disorders that map to this region.

Chromosomes, Fungal↗
PubMed1993

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↗
PubMed1993

New markers for linkage analysis of X-linked hypophosphataemic rickets.

Three polymorphic markers have been used to improve the genetic map of the region Xp22.1-p22.2, which contains the HYP (hypophosphataemic rickets) locus. DXS365 gave no recombinants with HYP, with a peak Lod score of 5.4 at theta = 0.0. A microsatellite marker mPA274 was derived for the DXS274 locus; it detects five alleles with a polymorphism information content of 0.55. Combining information from this microsatellite and the original DXS274 marker, probe CRI-L1391, the peak Lod score for DXS274 against HYP was 9.6 at theta = 0.02. A microsatellite associated with the DXS207 locus (mPA207) gave a peak lod score against HYP of 4.7 at theta = 0.14. A consideration of key recombinants and multilocus analysis suggests the gene order. Xpter-DXS207-DXS43-DXS197-(DXS365,HYP)- DXS274-DXS41-Xcen.

Base Sequence↗
PubMed1993

Detailed physical and genetic mapping in the region of plasminogen, D17Rp17e, and quaking.

We present here a detailed physical map encompassing over 600 kb of mouse Chromosome (Chr) 17 in the region of plasminogen, D17Rp17e, and quaking. This region is cloned in yeast artificial chromosomes (YACs). We have identified several CpG islands within this region from pulsed field gel mapping of mouse genomic DNA and YAC DNA. Five new DNA probes have been generated. One, D17Leh514, is a minimum of about 90 kb distal to plasminogen. Four, D17Leh513, D17Leh512, D17Leh511, and D17Leh510, are proximal to D17Rp17e, the closest previously described genetic marker to quaking viable and quaking lethal-1 mutations. We have genetically mapped D17Leh511 to within 0.15 cM of these mutations. The genetic distance to D17Rp17e from D17Leh511 is also 0.15 cM; the physical distance of less than 360 kb (minimum 200 kb) is consistent with an approximation of 2 Mbp per cM.

Animals↗
PubMed1993

Efficiency and specificity of gene isolation by exon amplification.

Exon amplification is an increasingly popular approach to the identification of transcribed sequences and will complement other strategies to isolate genes. We have used this system to amplify candidate exons from 32 cosmids, including 8 cosmids which span a well characterized 185-kb region of the human major histocompatibility class II region on Chromosome (Chr) 6. We have examined the efficiency, specificity, and reproducibility of the system in isolating exons from genes known to be present on particular cosmids and have determined the nature and frequency of artefact amplifications in routine cosmid screening. We were able to clone at least one exon from 88% (7/8) of all known genes tested (including exons which are differentially spliced) and obtained artefacts from 19% (6/32) of the cosmids tested. Such artefacts generally arise from the amplification of noncoding sequences flanked by regions with high homology to acceptor and donor splice junctions. We show that the exon amplification procedure can be used successfully with a wide variety of cosmids which have different numbers of genes and gene structures and describe several approaches to the characterization of novel exons cloned in this study.

Amino Acid Sequence↗
PubMed1993

Generation of high-density DNA markers from yeast artificial chromosome DNA by single unique primer-polymerase chain reaction.

We have developed a method for the whole sequence amplification of yeast artificial chromosome (YAC) DNA excised from preparative pulsed-field gel electrophoresis using single unique primer-polymerase chain reaction procedures. We used seven contiguous YAC clones, which span 2 Mbp of the Huntington disease gene region on 4p16.3, to amplify the YAC DNAs. The average size of the amplified DNA was approximately 300 bp long, and 12 DNA markers located on the YAC clones positively hybridized with these amplified products, implying that the sequences of the YAC clones were comprehensively amplified by our procedures. These amplified YAC DNAs greatly facilitate the characterization of YAC clones, leading to the detailed analysis of the defined chromosomal region.

Base Sequence↗
PubMed1993

A zinc-finger gene ZNF141 mapping at 4p16.3/D4S90 is a candidate gene for the Wolf-Hirschhorn (4p-) syndrome.

Chromosomal aneusomy is a major cause of reproductive wastage and congenital malformations in man. Zinc finger encoding genes would be good candidates for being involved in the multiple developmental defects associated with chromosomal aneusomy--by virtue of their role as transcriptional regulators, their abundance in the genome and their known association with specific developmental disorders. We have isolated and mapped a zinc finger encoding cDNA (ZNF141) of the C2-H2/KRAB subfamily to the 4p- (Wolf-Hirschhorn) syndrome (WHS) chromosome region. ZNF141 mapped to the distal end of the 2.2 Mb smallest region of deletion overlap of WHS, 300 kb from the 4p telomere on cosmid CD1 defining the anonymous locus D4S90. ZNF141 was expressed ubiquitously at low levels in the analysed tissue. The identification of a candidate gene for a chromosomal aneusomy syndrome belonging to a class of evolutionary conserved genes will provide options for studying its normal and abnormal expression during mammalian embryogenesis.

Abnormalities, Multiple↗
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↗