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M A Leversha

Publications and source records attributed to M A Leversha.

At least 19 recordsLinked to original sources
PubMed2003

Expression of p53, pRB, and p16 in lung tumours: a validation study on tissue microarrays.

Tissue microarrays have been created from 326 lung tumours, including 173 squamous cell carcinomas (SCCs) and 132 adenocarcinomas (ADs). In order to evaluate the usefulness of this microarray series, the expression of p53, p16, and Rb proteins was compared by immunohistochemistry on both the tissue microarrays and the corresponding whole sections for all 326 tumours. The presence of replicate punches improved both the yield and the concordance of data relative to the whole section results, so that the consensus score from the replicates agreed with the whole section result in more than 90% of informative tumours. The large number of tumours in this series also allowed significant differences in protein expression patterns to be detected between SCC and AD, the major subtypes of non-small cell lung carcinoma (NSCLC). SCC had higher levels of p53 staining (67% vs 52% in AD) and substantially increased p16 loss (SCC 75%, AD 53%) combined with greater retention of pRB expression (SCC 86% vs 67% in AD). The strong inverse correlation between p16 and pRB seen in SCC was essentially absent in AD. This study represents the largest single immunohistochemical survey of protein expression for p53, p16, and RB in NSCLCs.

Adenocarcinoma↗
PubMed2001

The physical maps for sequencing human chromosomes 1, 6, 9, 10, 13, 20 and X.

We constructed maps for eight chromosomes (1, 6, 9, 10, 13, 20, X and (previously) 22), representing one-third of the genome, by building landmark maps, isolating bacterial clones and assembling contigs. By this approach, we could establish the long-range organization of the maps early in the project, and all contig extension, gap closure and problem-solving was simplified by containment within local regions. The maps currently represent more than 94% of the euchromatic (gene-containing) regions of these chromosomes in 176 contigs, and contain 96% of the chromosome-specific markers in the human gene map. By measuring the remaining gaps, we can assess chromosome length and coverage in sequenced clones.

Chromosomes, Human, Pair 1↗
PubMed1999

High-resolution landmark framework for the sequence-ready mapping of Xq23-q26.1.

We have established a landmark framework map over 20-25 Mb of the long arm of the human X chromosome using yeast artificial chromosome (YAC) clones. The map has approximately one landmark per 45 kb of DNA and stretches from DXS7531 in proximal Xq23 to DXS895 in proximal Xq26, connecting to published framework maps on its proximal and distal sides. There are three gaps in the framework map resulting from the failure to obtain clone coverage from the YAC resources available. Estimates of the maximum sizes of these gaps have been obtained. The four YAC contigs have been positioned and oriented using somatic-cell hybrids and fluorescence in situ hybridization, and the largest is estimated to cover approximately 15 Mb of DNA. The framework map is being used to assemble a sequence-ready map in large-insert bacterial clones, as part of an international effort to complete the sequence of the X chromosome. PAC and BAC contigs currently cover 18 Mb of the region, and from these, 12 Mb of finished sequence is available.

Blotting, Southern↗
PubMed1997

From long range mapping to sequence-ready contigs on human chromosome 6.

Our aim is to construct physical clone maps covering those regions of chromosome 6 that are not currently extensively mapped, and use these to determine the DNA sequence of the whole chromosome. The strategy we are following involves establishing a high density framework map of the order of 15 markers per Megabase using radiation hybrid (RH) mapping. The markers are then used to identify large-insert genomic bacterial clones covering the chromosome, which are assembled into sequence-ready contigs by restriction enzyme fingerprinting and sequence tagged site (STS) content analysis. Contig gap closure is performed by walking experiments using STSs developed from the end sequences of the clone inserts.

Chromosomes, Human, Pair 6↗
PubMed1996

A member of the MAP kinase phosphatase gene family in mouse containing a complex trinucleotide repeat in the coding region.

We have identified a novel mouse gene encoding a protein that shows high homology to the dual-specificity tyrosine/threonine phosphatase family of proteins. The gene encodes a 5 kb transcript which is expressed predominantly in brain and lung and contains a translated complex trinucleotide repeat within the coding region. Using interspecific mouse backcross analysis, the gene has been localised to distal mouse chromosome 7. In human, homologous sequences are located in the syntenic region on distal chromosome 11p as well as to chromosome 10q11.2 and 10q22. The presence of a CG-rich trinucleotide repeat in the coding region provides a target for mutation which might result in loss of function or altered properties of this phosphatase.

Amino Acid Sequence↗
PubMed1995

A high-density YAC contig map of human chromosome 22.

We have constructed a high-resolution clone map of human chromosome 22 which integrates the available physical and genetic information, establishing a single consensus. The map consists of all classes of DNA landmarks ordered on 705 yeast artificial chromosomes (YACs) at an average landmark density of more than one per 70 kilobases. This map represents the practical limits of currently available YAC resources and provides the basis for determination of the entire gene content and genomic DNA sequence of human chromosome 22.

Chromosome Mapping↗
PubMed1995

Physical analysis of the tuberous sclerosis region in 9q34.

We report the construction of a physical map based on cloned DNA within the candidate region for the tuberous sclerosis complex (TSC1) gene on chromosome 9q34, between the markers D9S149 and D9S66. The DNA clones form three contigs consisting of 7 YACs, bridged by P1 and cosmid clones, and cover more than 950 kb of 9q34. Despite intensive screening of all available libraries, two gaps remain. A detailed physical map of much of this region was derived, and restriction mapping of the YAC, P1, and cosmid clones reveals novel CpG islands in this region. This set of genomic clones provides a resource for characterizing candidates for the TSC1 gene, guided by the location of CpG islands.

Base Sequence↗
PubMed1994

Localization of the gene (LAMA4) to chromosome 6q21 and isolation of a partial cDNA encoding a variant laminin A chain.

Laminin is a basement membrane glycoprotein composed of three nonidentical chains, A, B1, and B2. Variant chains such as merosin and S-laminin have been found in different tissues. We have isolated a cDNA encoding a novel laminin A variant that hybridizes to a 6.45-kb mRNA. Using amplification of genomic DNA and flow-sorted chromosomes we have assigned the gene (LAMA4) for this new laminin A variant to chromosome 6. Fluorescence in situ hybridization of a YAC clone further localized the gene to 6q21.

Amino Acid Sequence↗
PubMed1993

Coincidence painting: a rapid method for cloning region specific DNA sequences.

We have developed a novel coincidence cloning strategy, termed Coincidence Painting, which enables the rapid generation of large numbers of region specific sequences. Coincidence Painting utilises Degenerate Oligonucleotide Primed PCR (DOP-PCR) amplification of flow sorted derivative translocation chromosomes. The PCR products are hybridised in situ onto specific flow sorted chromosomes for coincident sequence selection. Eluted and reamplified material is then cloned using a novel insert end revelation and ligation technique. Cloned inserts range in size from 150-1300 bps of which approximately 54% appear to be single copy sequences. The cloning method permits the excision of vector free probe for library hybridisation screening and the small insert size facilitates analysis for the generation of sequence tagged sites (STSs). We have used such clones successfully for YAC screening by PCR and for cosmid screening by filter hybridisation. This new methodology should allow the rapid saturation with probes of regions defined by specific translocation breakpoints.

Base Sequence↗
PubMed1993

Duplicated KOX zinc finger gene clusters flank the centromere of human chromosome 10: evidence for a pericentric inversion during primate evolution.

Two related zinc finger (ZNF) gene clusters from the pericentromeric region of human chromosome 10, defined by cDNAs of the KOX series, have been cloned in yeast artificial chromosomes (YACs). The two clusters evolved by duplication of an ancestral gene cluster before the divergence of the human and great ape lineages. Included in cluster A are the ZNF gene sequences ZNF11A, ZNF33A, and ZNF37A, while cluster B comprises the related sequences ZNF11B, ZNF33B and ZNF37B. Genes from both clusters are expressed: cDNAs KOX2, KOX31 and KOX21 derive from ZNF11B, ZNF33A and ZNF37A, respectively. Further YACs have been isolated which link ZNF11A and ZNF33A to another gene, ZNF25, defined by cDNA clone KOX19. Therefore ZNF25 also forms part of cluster A, but has no counterpart in cluster B. Surprisingly, the KOX ZNF gene clusters are located on opposite sides of the centromere: cluster A maps to 10p11.2, while cluster B is in 10q11.2. This suggests the occurrence during primate evolution of a previously undescribed pericentric inversion subsequent to the cluster duplication. The evolution of this subset of KOX ZNF genes has therefore involved three types of genetic event: local gene duplication, gene cluster duplication, and chromosome rearrangement.

Amino Acid Sequence↗
PubMed1993

Physical mapping of chromosome 3p25-p26 by fluorescence in situ hybridisation (FISH).

As part of our effort to isolate and characterise the von Hippel-Lindau (VHL) disease gene, we constructed a physical map of chromosome 3p25-26 by fluorescence in situ hybridisation (FISH) studies on a panel of cytogenetic rearrangements involving this region. Biotinylated cosmid and lambda probes were hybridised to metaphase chromosome spreads and positioned with respect to each cytogenetic breakpoint. These studies unequivocally established the order of five loci linked to the VHL disease gene: cen-(RAF1,312)-D3S732-D3S1250-D3S601-D3S18 -pter and determined the position of three other probes within this map. These results ordered RAF1 and D3S732 for the first time, confirmed the localisation of D3S1250 between RAF1 and D3S601 and determined the position of D3S651 with respect to other chromosome 3p25-p26 loci. The establishment of an ordered set of cytogenetic aberrations will enable the rapid assignment of polymorphic and nonpolymorphic cloned sequences within the chromosome region 3p25-p26.

Cell Line, Transformed↗
PubMed1993

Structure and expression analysis of a member of the human glutamate dehydrogenase (GLUD) gene family mapped to chromosome 10p11.2.

Glutamate dehydrogenase (GLUD) is a key metabolic enzyme of the mitochondrion, playing an important role in mammalian neuronal transmission. GLUD deficiency has been associated with certain forms of neurodegeneration in the human cerebellum. Genomic DNA blot hybridization analysis and identification of a large number of GLUD-specific genomic clones have suggested that human GLUD is encoded by a multigene family consisting of at least six members. A functional GLUD gene, GLUD1, has been mapped to chromosome 10q22.3-23 and a full-length "processed" GLUD gene, GLUDP1, to chromosome Xq22-23. In the context of studing the structure, the role, and the chromosomal organization of the other family members, we have analysed in detail, a cosmid clone solely reactive with the 3' region of the GLUD cDNA. Structure and expression analysis of its GLUD-specific region suggests that it represents a truncated "processed" GLUD pseudogene. Fluorescence in situ hybridization using the entire cosmid as a probe, mapped this GLUD gene locus, termed GLUDP5, to chromosome 10p11.2.

Amino Acid Sequence↗
PubMed1993

Multiple self-healing squamous epitheliomata (ESS1) mapped to chromosome 9q22-q31 in families with common ancestry.

A gene (ESS1) predisposing to the development of multiple invasive but self-healing skin tumours (squamous cell epitheliomata) is tightly linked to the polymorphic DNA marker D9S53 (9q31) with a maximum lod score of 9.02 at a recombination fraction of 0.03. Multipoint linkage analysis demonstrates that the disease locus is most likely to lie between D9S58 (9q22.3-31) and ASSP3 (9q11-q22). Comparison of markers associated with ESS1 in independently ascertained families suggests a common origin of the disease and defines the location of ESS1. Haplotype studies indicate that the disease locus is most likely to lie between D9S29 (9q31) and D9S1 (9q22.1-q22.2).

Alleles↗