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R Williamson

Publications and source records attributed to R Williamson.

17 recordsLinked to original sources
PubMed1979

A nuclear precursor to human gamma-globin messenger RNA.

RNA isolated from human foetal liver at an erythroid stage of development was transferred from methyl mercury hydroxide agarose gels to diazobenzyloxymethyl paper. A 16S RNA species containing gamma-globin mRNA sequences was identified by hybridisation to 32P-labelled human gamma-globin cDNA recombinant plasmid pHgamma GI. This RNA is found only in the cell nucleus and is polyadenylated. Human globin gene transcription is thus analagous to that in mouse: interventing sequences are transcribed and processed from the pre-mRNA in the nucleus after polyadenylation.

Adult↗
PubMed1979

The structure of the human beta-globin gene in beta-thalassaemia.

Twenty-one cases of beta 0 and beta +-thalassaemia have been analysed by restriction endonuclease mapping. In most cases no deletion in the regions surrounding the beta- and delta-globin genes could be detected. However, in a single Asian case of beta 0-thalassaemia, homozygous clinically, one of the homologous chromosomes contained a beta-globin gene with a deletion of 600 base pairs of DNA and comprising most or all of the 3' end of the structural gene including the EcoRI restriction site within the beta-globin coding sequence.

DNA↗
PubMed1979

Structure of the human fetal globin gene locus.

We have derived a 'map' of restriction enzyme sites in and around the human gamma-globin genes. This has enabled us to show that there are two gamma-globin genes per haploid set, that the genes contain 'introns' within the same regions of DNA as the human beta and delta-globin genes, and that the genes are 3,500 base pairs apart. We conclude that the correct gene organisation of the human beta-like globin locus is GgammaAgammadeltabeta.

Chromosome Mapping↗
PubMed1979

Structure of the human G gamma-A gamma-delta-beta-globin gene locus.

We have constructed a physical map of the human G gamma-, A gamma-, delta-, and beta-globin genes. The previously described maps of the fetal and adult beta-like globin genes have been linked to one another by identification of a DNA fragment, generated by BamHI, that contains part of each of the A gamma- and delta-globin genes. The map obtained, which spans more than 40 kilobases, shows the following intergene distances: between G gamma and A gamma, 3500 base pairs; between A gamma and delta, 13,500 base pairs; and between delta and beta, 5500 base pairs. All genes are transcribed from the same DNA strand.

Adult↗
PubMed1979

The Friend virus genome: partial characterization of a complete DNA copy.

A complementary DNA probe has been prepared from the Friend murine erythroleukaemia virus complex released by Friend cells (FV cDNAD-) and Friend cells induced to differentiate (FV cDNAD+). Molecular hybridization analysis shows that: (a) FV cDNAD+ is close to being a complete copy of the virus genome and the distribution of sequences is uniform with respect to their distribution in the Friend virus genome. (b) Hybridization of 70S RNA from the cloned helper virus to the total FVc DNAD+ probe demonstrates that a large proportion of the cDNA is specific to the transforming spleen focus forming virus. (c) Hybridization of the probe to normal and transformed cell DNA shows that there are about seven Friend virus related genes in normal DNA and almost twice this amount in transformed cell DNA. A significant minor proportion (20%) of the cDNA probe anneals only to virus related sequences in the transformed cell DNA. (d) An analysis of the kinetics of annealing of the cDNA to an excess template RNA shows that the minimum base sequence complexity of the Friend virus complex is 4 x 10(6). (e) An analysis of the cross hybridization between FV cDNAD+ and 60 to 70S RNA isolated from virus released by uninduced and induced cells shows that the genome of the induced and uninduced Friend virus is almost identical.

Animals↗
PubMed1979

Characterization of the autolytic enzymes of Clostridium perfringens.

Clostridium perfringens and isolated walls of this organism autolysed rapidly when incubated in buffer at pH 7.0 with the release of free-reducing groups but no N-terminal amino acids. The predominant autolytic enzyme was an endo-beta-N-acetylglucosaminidase, and an endo-beta-N-acetylmuramidase was also present. The autolytic enzymes could be solubilized by extraction of the organisms with 5 M-LiCl and would then subsequently bind to and rapidly lyse walls of Micrococcus luteus and, more slowly, formamide-extracted walls of C. perfringens and walls of Bacillus subtilis. Lysis of C. perfringens walls by these extracted enzymes could not be demonstrated.

Acetylglucosaminidase↗
PubMed1979

Use of chromosomal translocations with in situ DNA hybridisation to confirm localisation of human 5S ribosomal RNA genes.

Two cases of chromosomal translocations involving the long arm of chromosome 1 were investigated for 5S ribosomal gene localisation using in situ hybridisation. In the first family, there was an interstitial translocation of 1q25-32 to chromosome 5; the 5S genes remained on chromosome 1. In the second family, there was a translocation of 1q42-44 to chromosome 21q12; the 5S gene locus in this case was translocated. This shows that the 5S ribosomal genes are at position 1q42-44, confirming a previous assignment based on adenovirus-induced uncoiling and on a partial trisomy (Steffensen et al., 1977).

Chromosome Banding↗
PubMed1978

Use of matrix-immobilised recombinant plasmids to purify chain-specific rabbit globin complementary DNAs.

The cloning of DNA sequences in plasmid recombinants has made it possible to amplify specific sequences to an extent that they can be used for preparative purposes. We describe the use of rabbit globin DNA sequences cloned in the plasmid pCR1 and covalently bound to Sepharose 4B for the purification of chain-specific rabbit alpha- and beta-globin cDNAs. These purified probes were then used to estimate the length of the alpha- and beta-globin DNA sequences inserted into the recombinant plasmid. The technique should allow the rapid isolation of sequence-specific cDNA, RNA and genomic DNA.

Animals↗
PubMed1977

Demonstration of two alpha-globin genes per human haploid genome for normals and Hb J Mexico.

Complementary DNA (cDNA) was prepared with viral RNA-dependent DNA polymerase using human globin messenger RNA (mRNA) as template. By selective hydridization to globin mRNA from beta-thalassaemics a probe which was greater than 85% complementary to alpha-globin mRNA was purified. This was hybridized in cDNA excess to human genomic DNA, and the rate and extent of hybridization confirmed that there are two genes for alpha-globin per haploid genome. Cellular DNA was also prepared from peripheral blood from cases expressing the alpha-globin chain mutant Hb J Mexico to varying extents. This DNA was identical in hybridization behaviour to normal DNA demonstrating that the imbalanced mutant chain synthesis seen physiologically is not due to a gene deletion.

Adult↗
PubMed1977

Genes for gamma-globin in human adult erythroid DNA.

Purified gamma-globin specific complementary DNA has been used to demonstrate the presence of the gene for gamma-globin in DNA from human adult red blood cells. This finding sheds doubt on any theory involving looping-out excision of genes to explain the switch over from synthesis of gamma-globin to beta-globin at birth.

Adult↗
PubMed1977

An approach to the understanding of messenger ribonucleic acid synthesis, processing and regulation in eukaryotes.

Eukaryotic mRNA isolation is now relatively simple, and molecular probes allow analysis of gene number and specific gene expression by nucleic acid hybridization. Compelling evidence is accumulating for high-molecular-weight nuclear precursors of mRNA species, but little is known of their processing or detailed molecular structure. This should become clear when heterogeneous nuclear RNA molecules containing only one mRNA sequence are analysed.

Animals↗
PubMed1975

Human globin gene analysis for a patient with beta-o/delta beta-thalassemia.

Complementary DNA (cDNA) was prepared with RNA-dependent DNA polymerase from human globin messenger RNA (mRNA). Annealing and translation experimenta with total mRNA from circulating cells from a patient with heterozygous beta/heterozygous beta-delta-o thalassemia (beta-o/delta beta-o-thalassemia) demonstrated no detectable mRNA for beta-globin. cDNA enriched in sequences homologous to beta-globin mRNA was prepared by hydroxylapatite fractionation of hybrids formed between beta-o/delta beta-o-thalassemic mRNA and cDNA made from mRNA from a patient with alpha-thalassemia (hemoglobin H disease). The rate of annealing of this beta-enriched cDNA to normal human nuclear DNA was that of a sequence present as only a single copy per haploid genome. The beta-enriched cDNA annealed to the beta-o-delta beta-o-thalassemia total DNA with approximately the same kinetics as to normal DNA, indicating that no total gene deletion of beta-globin genes from the diploid genome has occurred, although the accuracy of the technique could not exclude with certainty a partial deletion or a deletion of a beta-globin gene from only one of the haploid genomes. This demonstrates that at least one of the beta-o- or the delta beta-o-thalassemia haploid genomes in this case contains a substantially intact beta-globin gene.

Adolescent↗