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Biomedical subjects

I J Jackson

Publications and source records attributed to I J Jackson.

At least 91 records · Page 5Linked to original sources
PubMed1990

Characterization of TRP-1 mRNA levels in dominant and recessive mutations at the mouse brown (b) locus.

The mouse brown locus encodes a putative membrane-bound metalloenzyme, tyrosinase-related protein-1 (TRP-1). We have examined the effect on mRNA expression of the locus of a number of mutant alleles. The common null mutant allele, brown, produces wild-type levels of TRP-1 mRNA, which is nonfunctional. Another recessive allele, cordovan-Harwell, has an intermediate, dark-brown phenotype and produces only very low levels of presumably normal TRP-1 mRNA. Two dominant alleles appear to act by killing the melanocyte in which they are expressed. One of them, Light, has normal size and amounts of TRP-1 mRNA. The other, White-based brown, produces no detectable TRP-1 mRNA. It has a gross DNA rearrangement at the 5' end, and we speculate that this results in activation of transcription of sequences not usually seen in melanocytes, and that this is toxic to the cell. The relationship between phenotype and molecular structure at the locus is discussed, and we draw some general principles applicable to other developmental genes.

Animals↗
PubMed1990

Phenotypic rescue of mutant brown melanocytes by a retrovirus carrying a wild-type tyrosinase-related protein gene.

A mouse cDNA for the developmentally controlled, melanocyte-specific protein, tyrosinase-related protein 1 (TRP-1), was previously cloned and reported to show genetic linkage with the coat-colour locus brown (b) on mouse chromosome 4. The cDNA has been inserted into a retroviral vector derived from Moloney murine leukaemia virus, under the control of the human histone H4 promoter. This vector was used to infect melanocytes of the immortal line melan-b, which are homozygous for the b mutation and which display light brown pigmentation in culture. Infected cultures containing between 0.2 and 2 copies of provirus per cell displayed an altered phenotype: 20-50% of cells now had the black to dark brown colour characteristic of cultured wild-type (Black, B/B) mouse melanocytes. Thus the TRP-1 gene complements the brown mutation. We conclude that TRP-1 is the product of the wild-type b-locus.

Animals↗
PubMed1989

'Cockpit' drill.

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Anesthesiology↗
PubMed1989

Recurrent anaphylactoid reaction during caesarean section.

A 28-year-old woman presented for emergency Caesarean section at 31 weeks' gestation with deranged liver function and a history of recurrent anaphylactoid reactions during previous pregnancy-related anaesthetics. The anaesthetic management and outcome of this case is presented.

Adult↗
PubMed1988

A cDNA encoding tyrosinase-related protein maps to the brown locus in mouse.

A mouse melanoma cDNA clone was isolated by virtue of its reactivity with two antisera raised against tyrosinase (EC 1.14.18.1) from two species, hamster and mouse. The cDNA (5A) cross-hybridizes with another, pMT4 [Shibahara, S., Tomita, V., Sakakura, T., Nager, C., Bhabatosh, C. & Muller, R. (1986) Nucleic Acids Res. 14, 2413-2427], previously thought to encode mouse tyrosinase. Two other cDNAs, one human and one mouse, have been reported recently [Kwon, B. S., Haq, A. K., Pomerantz, S. H. & Halaban, R. (1987) Proc. Natl. Acad. Sci. USA 84, 7473-7477; and Yamamoto, H., Takeuchi, S., Kudo, T., Makino, K., Nakata, A., Shinoda, T. & Takeuchi, T. (1987) Jpn. J. Genet. 62, 271-277] as candidates for tyrosinase, and they map at or very close to the mouse albino (c) locus. The proteins they encode are very similar to each other but are distinct from (although related to) the pMT4-encoded protein. Here I use recombinant inbred strains to localize pMT4 at or close to the mouse brown (b) locus. I suggest that the gene mapping to c is the authentic tyrosinase gene, whereas that mapping to b encodes a tyrosinase-related protein. All b mutations in laboratory strains are associated with the same diagnostic Taq I fragment, suggesting that all derive from the same original mutation. I discuss possible function(s) of the tyrosinase-related protein.

Animals↗
PubMed1987

Potential leaks from anaesthetic machines. Potential leaks through open Rotameter valves and empty cylinder yokes.

Twenty anaesthetic machines were examined to detect leakage of fresh gas through open Rotameter flow control valves and empty cylinder yokes. Significant leakage was demonstrated in most machines. Any leakage in machines which comply with ISO 5358, where oxygen is the last gas into the common gas manifold, is selective for nitrous oxide and, conversely, it is selective for oxygen in machines where oxygen is the first gas into the common gas manifold. Leakage is augmented by back pressure from ventilators that function as minute volume dividers. In ventilated patients the leakage described may contribute to hypoventilation and patient hypoxia or to pollution of the operating theatre and patient awareness.

Anesthesia, Inhalation↗
PubMed1986

The developmental expression of the gene for TFIIIA in Xenopus laevis.

The sequence of the trans-acting positive transcription factor TFIIIA has been deduced by sequencing cDNA and genomic DNA clones. Using DNA from a homozygous diploid animal we show that there is one gene for TFIIIA per haploid genome of X. laevis. Protein sequencing of proteolytic fragments of TFIIIA orients the protein in its interaction with the internal control region (ICR) of the 5S RNA gene. The protein lies along the DNA with its carboxyl terminus at the 5' end of the ICR and its amino terminus at the 3' end. The developmental pattern of TFIIIA and its mRNA during oogenesis and embryogenesis are consistent with the idea that the abundance of TFIIIA plays an essential role in the developmental change in 5S RNA gene expression. The change to almost exclusive somatic 5S RNA gene expression by gastrulation occurs using either the TFIIIA that was synthesized by oocyte and/or TFIIIA synthesized from maternal mRNA.

Amino Acid Sequence↗
PubMed1986

The murine Hox-2 cluster of homeo box containing genes maps distal on chromosome 11 near the tail-short (Ts) locus.

Two probes derived from a mouse recombinant lambda-clone (H24.1), that contains a sequence closely homologous to the Drosophila antennapedia homeo box, were mapped to mouse chromosome (MMU) 11 by filter hybridization of somatic cell hybrid DNA. This sequence is highly homologous to a human homeo box gene (HOX2) and appears to represent one of the two genes in the Hox-2 cluster previously assigned to MMU 11. To regionally map the Hox-2 cluster, we have carried out in situ hybridization of the two H24.1 probes and of an independently isolated Hox-2 probe. The autoradiographic silver grain distributions were similar in all three experiments with a peak over band 11D. This region contains the locus for the tail-short (Ts) mutation which causes skeletal abnormalities in heterozygotes and early embryonic death in homozygotes.

Animals↗
PubMed1984

Domains of the positive transcription factor specific for the Xenopus 5S RNA gene.

The 40 kd positive transcription factor that interacts with the 50 nucleotide internal control region of 5S ribosomal RNA genes in Xenopus can be subdivided into three functional domains by proteolytic cleavage. At one end of the protein is a 10 kd domain that is required for efficient RNA transcription but not for binding to the DNA. This adjoins a second domain that binds to the 5' end of the internal control region, a region of the DNA known to contribute only weakly to binding the protein but one that is essential for RNA transcription. The removal of both of these protein domains leaves a half of the protein that binds only to the 3' side of the control region and is inactive in promoting transcription. Quantitative DNA binding and in vitro transcription experiments show that only a single molecule of 40 kd factor binds to the internal control region, and that this stoichiometry is sufficient to give maximal stimulation of 5S RNA transcription in a reconstituted system. Consideration of the essential DNA contact points of the factor, taken together with the constraints imposed by a 1:1 protein to DNA stoichiometry permit the linear projection of the extended protein molecule onto its binding site along the internal control region of the 5S RNA gene.

Animals↗
PubMed1981

The absence of introns within a human fibroblast interferon gene.

Experiments in which immobilised restriction fragments of genomic DNA were hybridised with a cloned human fibroblast interferon cDNA indicate that the homologous chromosomal genes exist in only one basic arrangement. This is in marked contrast to recent studies by Nagata et al. (1) showing that there are at least eight gene arrangements for human leukocyte interferon. Having isolated a chromosomal human fibroblast interferon gene from a gene bank, we conclude from nucleotide sequencing studies that there is a complete absence of introns within the RNA-coding region. In view of a similar observation recently made for a human leukocyte interferon gene (1), it would appear as if interferon genes in general are unlike the vast majority of eukaryote genes in this respect.

Base Sequence↗
PubMed1981

The isolation, mapping and transcription in vitro of a beta 0-thalassaemia globin gene.

The red blood cell precursors of a patient with homozygous beta 0-thalassaemia have previously been shown to contain nuclear, but not cytoplasmic, beta-globin-specific transcripts. We describe the isolation of a beta-globin gene from this patient as a recombinant bacteriophage chromosome. Restriction-enzyme cleavage-site mapping experiments demonstrate no detectable deletions, insertions or major rearrangements in this thalassaemia gene. Two different techniques show that the gene isolated is transcribed as efficiently in vitro as the normal beta-globin gene.

Base Sequence↗