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K J Barrett

Publications and source records attributed to K J Barrett.

28 records · Page 2Linked to original sources
PubMed1987

Human ferritin H and L sequences lie on ten different chromosomes.

In humans, the H (heavy) and L (light) chains of the iron-storage protein ferritin, are derived from multigene families. We have examined the chromosomal distribution of these H and L sequences by Southern analysis of hybrid cell DNA and by chromosomal in situ hybridization. Our results show that human ferritin H genes and related sequences are found on at least seven different chromosomes while L genes and related sequences are on at least three different chromosomes. Further, we have mapped the chromosomal location of expressed genes for human H and L ferritin chains and have found an H sequence which may be a useful marker for idiopathic hemochromatosis.

Animals↗
PubMed1985

Ferritin H and L chains are derived from different multigene families.

This paper explores the complexity of human ferritin H and L genes. We show that essentially full-length cDNA clones for human ferritin H and L chains do not cross-hybridize under moderate stringency conditions and present the first comparisons of H and L mRNAs and genes from the same species. Northern blot analyses indicate that the H and L mRNAs each contain about 1100 nucleotides. Subprobe analyses of Southern blots show that both H and L genes exist as multiple gene families. Both the 5' and 3' sequences of the H genes are heterogeneous, whereas the 3' end of the L gene is relatively conserved.

Base Sequence↗
PubMed1985

The Igh-V locus of MRL mice: restriction fragment length polymorphism in eleven strains of mice as determined with VH and D gene probes.

The MRL strain of mice is a model system that closely parallels the human autoimmune disease systemic lupus erythematosus. Our analysis of the variable region genes of MRL mice showed that the MRL/lpr D genes were similar to those of the C3H mouse (Igh-C allotype j). This result was unexpected, because previous studies of the MRL/lpr and MRL/+ substrains suggested that they are allotype a at the Igh-1 (gamma 2a) locus of the constant region. The Igh-V (heavy chain variable region) locus of the MRL/lpr and MRL/+ strains of mice and their parents were therefore examined by restriction fragment length polymorphism with probes for the DSP2 and DFL16 gene families and with two cloned VH probes. Five other strains of mice were also included because the heavy chain locus of the LG mouse, which is the major progenitor of the MRL strains, has not been studied. The MRL substrains and the LG and C3H parents were indistinguishable at all the Igh-V loci studied. These results suggest that the MRL substrains and their LG parent are haplotype j at the Igh-V locus. The results obtained with D gene probes show that the DSP2 gene family is more polymorphic than the DFL16 gene family, which is relatively conserved. We have assigned Igh-V haplotypes for the four VH loci to the 11 strains of mice studied.

Animals↗
PubMed1984

Isolation and characterization of a cDNA clone for human ferritin heavy chain.

Ferritin, the main iron-storage protein, is composed of two partially homologous subunits, heavy (H) and light (L), with MrS of 21,000 and 19,000, respectively. We have isolated a cDNA clone for human ferritin H chains by screening a human lymphocyte cDNA library with synthetic oligodeoxyribonucleotides. The oligonucleotide sequences were derived from two pentapeptides found in human spleen ferritin. The selected clone hybridized to both probes and selected H-chain mRNA, but not L-chain mRNA, when hybridized to HeLa cell mRNA. These results indicate that the cloned DNA codes for a H chain of human ferritin. Since the amino acid sequence derived from the cloned DNA was almost identical to the partial amino acid sequence of a minor component found in human spleen ferritin, we conclude that the minor sequence found in human spleen ferritin must be a H subunit. Genomic analysis gives a complex pattern that suggests that ferritin H chains are encoded by a multigene family or have an unusually large number of exons.

Base Sequence↗
PubMed1983

The bacteriophage P4 alpha gene is the structural gene for bacteriophage P4-induced RNA polymerase.

Two temperature-sensitive mutants of satellite phage P4 which do not synthesize P4 DNA at the nonpermissive temperature have been isolated. One of these phage is mutated in the P4 alpha gene. It complements a P4 delta mutant, but not a P4 alpha amber mutant; both mutants are phenotypically identical to alpha amber mutants in all properties studied. They synthesize P4 early proteins 1 and 2 as well as two additional P4-induced early proteins, 5 and 6, which are described here. P4 late proteins are not synthesized by these mutants and cannot be transactivated by helper phage P2. The mutants are unable to transactivate P2 late proteins from a P2 AB mutant. The P4 RNA polymerase activity which has been suggested to be involved in P4 DNA synthesis is not detected at the nonpermissive temperature. The P4 polymerase activity in partially purified extracts prepared from cells infected with the mutant at the permissive temperature is temperature sensitive. Reduced activity is found in vitro when these extracts are preincubated at 41 degrees C or assayed at temperatures higher than 37 degrees C. Thus, the P4 RNA polymerase is the product of the alpha gene. Temperature shift experiments show that the alpha gene product is required until late in the P4 cycle.

Coliphages↗
PubMed1978

Transcription of the chicken ovalbumin and conalbumin gene during early secondary induction with estrogens.

Estrogens stimulate the rate of transcription of the ovalbumin and conalbumin gene in the chicken oviduct. The synthesis of ovalbumin and conalbumin mRNA was studied in isolated nuclei. RNA synthesized in vitro was distinguished from preexisting nuclear RNA by affinity labeling the in vitro products with a mercurated nucleotide and subsequent purification of the Hg-RNA on SH-agarose. The content of ovalbumin and conalbumin mRNA sequences in the in vitro transcripts was determined by hybridization to cDNA. After the withdrawal of implanted hormones from chickens, the synthesis of conalbumin and ovalbumin RNA increased 2.5- and at least 20-fold, respectively, by treatment with estrogens. The maximal rate of transcription of the conalbumin gene is achieved within 2 h after estrogen induction, whereas the rate of transcription of the ovalbumin gene becomes maximal after a lag of several hours. These results demonstrate that estrogens affect two genes in the same target cell differently.

Amanitins↗
PubMed1972

A transcribing activity induced by satellite phage P4.

Satellite bacteriophage P4 induces a new transcribing enzyme that synthesizes polyriboguanylic acid in the presence of the poly(dG).poly(dC) homopolymer pair. This transcribing activity was partially purified and shown to be distinct from the host RNA polymerase. Analysis of conditional lethal mutants suggests that this new enzyme is necessary for replication of phage DNA.

Antibody Specificity↗
PubMedDate not supplied

Identification and complementation of a mutation to constitutive filamentous growth in Ustilago maydis.

Pathogenicity of the corn smut fungus Ustilago maydis involves the formation of a filamentous, infectious dikaryon by fusion of compatible, yeastlike haploid cells. The mating-type loci, a and b, regulate cell fusion and establishment of the dikaryotic cell type, respectively. On solid medium, compatibility at the mating-type loci, in particular heterozygosity at the b locus, is manifested by the formation of aerial hyphae on colonies formed by mating cells. We have employed this "fuzzy" phenotype to identify haploid mutants that constitutively form hyphal filaments and forego cell division by budding. A total of 125 such mutants have been isolated; characterization of one mutant (termed rem1-1) revealed that it can participate in infection of the host plant, although it must be paired with a compatible, wild-type mating partner. That is, mutation to the mycelial phenotype is not sufficient to allow a haploid strain to be pathogenic by itself. A cosmid has been isolated that restores the ability of an rem1-1 mutant to grow with a budding phenotype. Localization of the complementing region on cosmid DNA allowed the construction of an additional mutation by gene disruption. Coinoculation of plants with two compatible strains, each carrying the disruption mutation, gave greatly reduced disease symptoms. The analysis of the rem1 gene should contribute to an understanding of dimorphic growth and pathogenesis in U. maydis.

Base Sequence↗