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K J Robson

Publications and source records attributed to K J Robson.

At least 73 records · Page 4Linked to original sources
PubMed1993

Approaches to studying genetic diversity of Plasmodium falciparum using a DNA sequence variation.

Sequence variation in the calmodulin and thrombospondin related anonymous protein (TRAP) genes has been examined following amplification using the polymerase chain reaction (PCR). The intron of the calmodulin gene has four repeating motifs which vary in length: three of these contain a dinucleotide repeat, dA-dT, while the fourth is a pentameric repeating unit dA-dT-dA-dT-dT. These DNA polymorphisms can be applied to the study of parasite populations in mixed infections and in strain identification. The known sequence diversity in the TRAP gene has been converted to an RFLP analysis following PCR amplification. Comparisons between the chemical cleavage method and the direct sequencing of PCR amplified products of the TRAP gene, suggest that the latter method is preferable when analysing sequences as variant as TRAP.

Animals↗
PubMed1992

The determination of total filtration on mammographic X-ray sets.

Data produced by a computer model are presented which allow the amount of molybdenum filtration on a molybdenum target mammographic X-ray set to be estimated from the measurement of the half value layer (HVL) in aluminium. Existing data refer either to tungsten target tubes or to molybdenum target tubes for a single anode angle and a constant potential waveform with the compression plate present. In addition to the tube voltage, the present data take account of the waveform of the tube potential and target angle. The results of an experimental verification of the model are presented and the effect of the geometry used in the experimental set-up discussed. Theoretical predictions of the molybdenum filter thickness made using the data from the model are in good agreement with the measured filter thickness, provided that attention is paid to the experimental geometry.

Computer Simulation↗
PubMed1991

The structure of the calmodulin gene of Plasmodium falciparum.

The calmodulin gene and its flanking sequences from the malaria parasite, Plasmodium falciparum, have been analysed. The structure of this gene is unique amongst other known calmodulin genes. It exists as a single copy on chromosome 14 and has a single intron. The nucleotide sequence of this 4-kb region suggests the existence of three transcriptional units, each separated by a highly A+T-rich sequence. Sequences controlling gene expression might be expected to occur in these intergenic regions. The predicted protein sequences suggest that these other genes are transcribed in different orientations. Primer extension studies suggest that calmodulin mRNA has a major start site 62 bases upstream of the initial ATG. The calmodulin gene possesses consensus eukaryotic TATA, CAAT box, polyadenylation and splice junction sequences. This is the first detailed report of the DNA sequence surrounding a housekeeping gene in P. falciparum.

Amino Acid Sequence↗
PubMed1990

Polymorphism of the TRAP gene of Plasmodium falciparum.

Natural sequence variation of the thrombospondin related anonymous protein (TRAP) gene of Plasmodium falciparum has been investigated by DNA analysis following the polymerase chain reaction amplification, and this shows the gene to be highly polymorphic. The region containing the sequence motif Trp-Ser-Pro-Cys-Ser-Val-Thr-Cys-Gly (WSPCSVTCG), common to TRAP, the circumsporozoite protein, properdin, and thrombospondin, was invariant. Elsewhere in the molecule, over 50 amino acid substitutions are described including the insertion of an in-frame, small-variable tandemly repeating motif between amino acid residues 352 and 353. Only one silent mutation was observed. Most nucleotide changes that occur in the first two codon positions result in conservative amino acid changes. Restriction fragment length polymorphism (RFLP) analysis was used to examine inheritance of TRAP in a cross between the HB3 and 3D7 clones of P. falciparum. Out of nine progeny examined, four possessed the HB3 gene and five the 3D7 gene. The TRAP gene hybridized to chromosome 13. Previous work has shown that a subtelomeric region of chromosome 13 from the 3D7 parent (marked by the HRP-III gene) was favoured strongly in this cross. The TRAP gene, however, is over 1 Mb away from this subtelomeric region and exhibits no such linkage because of chromosome crossovers. Five geographically separate isolates shared the same TRAP sequence as well as the same variant of the Th2R/Th3R region from the circumsporozoite protein. The correlation between independent markers in these isolates suggests that they have a common provenance.

Amino Acid Sequence↗
PubMed1988

A highly conserved amino-acid sequence in thrombospondin, properdin and in proteins from sporozoites and blood stages of a human malaria parasite.

As a consequence of gene cloning and DNA sequencing several gene families are emerging in the field of cell-cell recognition. These include immunoglobulins, integrins, certain extracellular glycoproteins and a family of functionally unrelated proteins which include factor B. We report here the cloning and sequencing of a gene from Plasmodium falciparum, coding for a protein we call thrombospondin related anonymous protein (TRAP), which shares certain sequence motifs common to other well-characterized proteins. The most significant homology is based around the sequence Trp-Ser-Pro-Cys-Ser-Val-Thr-Cys-Gly (WSPCSVTCG), present in three copies in region I of thrombospondin (TSP), six copies in properdin (P) and one copy in all the circumsporozoite (CS) proteins sequenced so far. TRAP also shares with certain extracellular glycoproteins, including TSP, the cell-recognition signal Arg-Gly-Asp (RGD), which has been shown to be crucial in the interaction of several extracellular glycoproteins with members of the integrin superfamily. Unlike the CS protein, TRAP is expressed during the erythrocytic stage of the parasite life cycle.

Amino Acid Sequence↗
PubMed1988

Further studies of gene deletions that cause Duchenne and Becker muscular dystrophies.

Fetal muscle cDNA clones covering at least 11.4 kb of the Duchenne muscular dystrophy (DMD) gene sequence were used to identify a deletion-prone region in DNA from DMD and Becker muscular dystrophy (BMD) patients. Of 36 BMD cases, 17 (47%) had deletions and all of the deletions began in the same intron of the gene. Of 107 DMD patients, 27 (25%) were deleted for this region, and 19 deletions originate in the same intron. Using a cDNA probe for an adjacent region of the gene, 32 new deletions were detected in DMD patients (total 44%). No new BMD deletions were detected. The DMD deletions were very heterogeneous. Thus two cDNA probes covering 2.4 kb could detect 53% of these deletions. Considering the whole locus, DMD and BMD are caused by a deletion of the gene sequence in at least 67% of cases.

Chromosome Deletion↗
PubMed1987

GT to AT transition at a splice donor site causes skipping of the preceding exon in phenylketonuria.

Classical Phenylketonuria (PKU) is an autosomal recessive human genetic disorder caused by a deficiency of hepatic phenylalanine hydroxylase (PAH). We isolated several mutant PAH cDNA clones from a PKU carrier individual and showed that they contained an internal 116 base pair deletion, corresponding precisely to exon 12 of the human chromosomal PAH gene. The deletion causes the synthesis of a truncated protein lacking the C-terminal 52 amino acids. Gene transfer and expression studies using the mutant PAH cDNA indicated that the deletion abolishes PAH activity in the cell as a result of protein instability. To determine the molecular basis of the deletion, the mutant chromosomal PAH gene was isolated from this individual and shown to contain a GT-- greater than AT substitution at the 5' splice donor site of intron 12. Thus, the consequence of the splice donor site mutation in the human liver is the skipping of the preceding exon during RNA splicing.

Amino Acid Sequence↗
PubMed1985

Nucleotide sequence of a full-length complementary DNA clone and amino acid sequence of human phenylalanine hydroxylase.

A full-length human phenylalanine hydroxylase complementary DNA (cDNA) clone was isolated from a human liver cDNA library, and the nucleotide sequence encoding the entire enzyme was determined. The cDNA clone contains an inserted DNA fragment of 2448 base pairs, including 19 base pairs of poly(A) at the 3' end. The first methionine codon occurs at nucleotide position 223, followed by an open reading frame of 1353 base pairs, encoding 451 amino acids. Translation of the nucleotide sequence in the open reading frame predicts the amino acid sequence of human phenylalanine hydroxylase. The human protein shows a 96% amino acid sequence homology with the corresponding rat enzyme. The determination of the complete primary structure for phenylalanine hydroxylase represents the first among mixed-function oxidases.

Amino Acid Sequence↗
PubMed1985

Extensive restriction site polymorphism at the human phenylalanine hydroxylase locus and application in prenatal diagnosis of phenylketonuria.

A total of 10 restriction site polymorphisms have been identified at the human phenylalanine hydroxylase locus using a full-length human phenylalanine hydroxylase cDNA clone as a hybridization probe to analyze human genomic DNA. These polymorphic patterns segregate in a Mendelian fashion and concordantly with the disease state in various PKU kindreds. The frequencies of the restriction site polymorphisms at the human phenylalanine hydroxylase locus among Caucasians are such that the observed heterozygosity in the population is 87.5%. Thus, most families with a history of classical phenylketonuria can take advantage of the genetic analysis for prenatal diagnosis and carrier detection of the hereditary disorder.

Female↗
PubMed1984

Sequence comparison of rat liver phenylalanine hydroxylase and its cDNA clones.

Classical phenylketonuria, an inborn error in metabolism, is caused by a deficiency of the hepatic enzyme phenylalanine hydroxylase. The identification of putative cDNA clones coding for rat liver phenylalanine hydroxylase by hybrid-selected translation has previously been reported [Robson, K. J., Chandra, T., MacGillivray, R. T. A., & Woo, S. L. C. (1982) Proc. Natl. Acad. Sci. U.S.A. 79, 4701-4705]. The authenticity of the clones, however, could not be definitively ascertained at the time because of a lack of amino acid sequence data of the enzyme in the literature. Purified rat liver phenylalanine hydroxylase was subjected to cyanogen bromide treatment, and the resulting fragments were used for N-terminal amino acid sequence analysis. The partial amino acid sequence was then compared to that deduced from an open reading frame in the nucleotide sequence of the cDNA clones. A perfect match of 17 amino acid residues was found between the two sequences following a unique methionine codon present in the nucleotide sequence, thereby providing unambiguous evidence for the identity of the rat liver phenylalanine hydroxylase cDNA clones.

Amino Acid Sequence↗