A sad story told sadly: the prospects for U.S.-EU food trade wars.
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Biotechnology↗
Biomedical subjects
C Lister
Publications and source records attributed to C Lister.
Physical map and organization of Arabidopsis thaliana chromosome 4.
A physical map of Arabidopsis thaliana chromosome 4 was constructed in yeast artificial chromosome clones and used to analyze the organization of the chromosome. Mapping of the nucleolar organizing region and the centromere integrated the physical and cytogenetic maps. Detailed comparison of physical with genetic distances showed that the frequency of recombination varied substantially, with relative hot and cold spots occurring along the whole chromosome. Eight repeated DNA sequence families were found in a complex arrangement across the centromeric region and nowhere else on the chromosome.
Arabidopsis↗
Differential inhibition of DNA synthesis by paracetamol in the rat testis and GI tract.
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Acetaminophen↗
A new theory of enterorecirculation of amino acids and its use for depleting unwanted amino acids using oral enzyme-artificial cells, as in removing phenylalanine in phenylketonuria.
Oral binders remove intestinal bile acid and prevent its reabsorption and recycling thereby lowering systemic cholesterol levels. The results in this paper demonstrate the presence of another extensive enterorecirculation for amino acids. Pancreatic and other glandular secretions into the intestine contain large amounts of proteins, enzymes and polypeptides. Tryptic digestion converts these into amino acids which are then reabsorbed back into the body as they pass down the intestine. This paper shows that this forms a large enterorecirculation of amino acids between the body and intestine. The dietary protein source of amino acids is negligible when compared to the endogenous source, since this paper shows that protein-free diet did not alter the intestinal amino acid concentration. This raises the possibility of using this for the selective depletion of specific body amino acids. In this paper we use a phenylketonuria (PKU) model in rats to test the use of this hypothesis. In PKU rats, artificial cells microencapsulated phenylalanine ammonia lyase (PAL) given orally is more effective than a phenylalanine-free diet. The enzyme artificial cells are more efficient in lowering PHE in the intestine, plasma and cerebrospinal fluid. Compared to PKU on PHE-free diet, this has resulted in better weight gain and general physical condition. Preliminary studies also show that artificial cells microencapsulated asparaginase, glutaminase and tyrosinase given orally can deplete the corresponding amino acid from the intestine.
Amino Acids↗
Integration of CAPS markers into the RFLP map generated using recombinant inbred lines of Arabidopsis thaliana.
Konieczny and Ausubel have described a technique whereby Arabidopsis thaliana loci can be rapidly mapped to one of the ten chromosome arms using a small number of F2 progeny from crosses between the ecotypes Landsberg erecta and Columbia. The technique involves the use of 18 co-dominant, cleaved amplified polymorphic sequence (CAPS) markers which are evenly distributed throughout the Arabidopsis genome. We have mapped these 18 markers using recombinant inbred (RI) lines generated in our laboratory. These data enable a better integration of loci mapped relative to the CAPS markers into the restriction fragment length polymorphism (RFLP) map generated using Arabidopsis RI lines.
Arabidopsis↗
Hospital administrative costs.
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Hospital Administration↗
Transposon-induced inversion in Antirrhinum modifies nivea gene expression to give a novel flower color pattern under the control of cycloidearadialis.
The nivea (niv) gene of Antirrhinum majus encodes chalcone synthase, an enzyme involved in synthesis of anthocyanin pigments. The nivrec:98 allele contains a single copy of the transposon Tam3 inserted at the niv locus. A large chromosomal rearrangement derived from this mutant has been shown to be flanked by two copies of Tam3. In this study, we compared sequences involved in this rearrangement with their progenitor sequences and concluded that the rearrangement is an inversion resulting from an aberrant transposition occurring shortly after replication of Tam3 that left both copies of Tam3 active after the rearrangement. Excision of Tam3 from its position adjacent to the niv coding region resulted in a novel distribution of anthocyanin pigment in the flower tube, caused by the interaction of the new sequences with the remnant of the niv promoter. The new sequences upstream of niv serve both to enhance niv transcription and to redirect the pattern of gene expression, placing niv under the control of the gene cycloidearadialis, which determines the morphogenetic polarity of the flower.
Alleles↗
A preclinical screening test for modified hemoglobin to bridge the gap between animal safety studies and use in human.
The infusion of large amount of modified hemoglobin as blood substitute can potentially result in hypersensitivity and anaphylactic reactions, antibody-antigen reactions and others. Animal safety studies are important. However, response in animals may not be the same as in human. Before injecting into human, we may need to use an in-vitro screening procedure. One approach is based on testing the effects of modified Hb on complement activation (C3a) of human plasma. This paper describes this screening test. It also discusses how this may potentially be used. For instance using this to test for contamination from trace membrane fragments with blood group antigen or lipids, antibody-antigen complexes, endotoxin, trace fragments of microorganisms, residual amounts of some polymers, emulsifying agents, and organic solvents. There is also the possibility of obtaining plasma from a very large human population and analyse each of these to study the epidemiology of adverse reactions in different groups and types of patients.
Anaphylaxis↗
Immunological effects of hemoglobin, encapsulated hemoglobin, polyhemoglobin and conjugated hemoglobin using different immunization schedules.
Repeated subcutaneous immunizing injections into rats of Freund's adjuvant containing rat hemoglobin or o-raffinose rat polyhemoglobin did not result in increase in IgG antibody titers. However, heterologous hemoglobin injected as above is antigenic (49.50 + 6.70 % CPM). Crosslinking heterologous hemoglobin into o-raffinose polyhemoglobin further increased its antigenicity (75.60 + 4.08). Thus, unlike homologous hemoglobin, cross-linking of heterologous hemoglobin increased its antigenicity. Liposome encapsulated homologous hemoglobin injected subcutaneously with or without Freund's adjuvant did not show antigenicity. Encapsulated heterologous hemoglobin resulted in a minimal increase in antibody titers (10.73 + 4.64) only with Freund's adjuvant, but no increase when injected without Freund's adjuvant. Conjugated heterologous hemoglobin (PEG-Hb) injected intravenously by itself at weekly intervals did not result in significant increase in antibody titers on the 5th week.
Animals↗
Development of an efficient transposon tagging system in Arabidopsis thaliana.
We are currently developing a transposon tagging system in Arabidopsis thaliana using the maize transposable elements Ac and Ds. In order to make the system as efficient as possible, four different antibiotic resistance markers have been tested for their usefulness in monitoring excision and reinsertion of transposons in the Arabidopsis genome. Owing to the low transposition frequency of wild-type Ac in Arabidopsis we have also tested a number of modifications to the Ac element. Deletion of the CpG-rich region in the transposase 5' untranslated leader was found to significantly increase the activity of Ac in Arabidopsis. In our first non-targeted tagging experiment, 200 individuals with an inherited transposed Ac element have been collected and their progeny are being screened in families of twelve for segregation of mutant phenotypes. A two-element system, using Ac and Ds, is also being developed and a way of stabilising the Ds-induced mutations by counter selecting plants carrying the transposase source is being investigated. The Agrobacterium T-DNA insertions carrying the different transposons are currently being mapped onto the Arabidopsis RFLP map. Inverse polymerase chain reaction (IPCR) is being used to generate flanking DNA probes, that will be used on the RFLP blots to map the T-DNA relative to the other known markers. Once the first few have been mapped the first targeted tagging experiment will be initiated.
Arabidopsis↗
Sequence and structure in the concept development of children with emotional and behavioral difficulties.
We investigated the order of acquisition of concepts and cognitive processes in children with emotional and behavioral difficulties and the extent to which these children show similarity to ordinary children in sequence and structure of development. Similarity in developmental sequence was strongly supported by scalogram analyses and has clear implications for organizing teaching, but similarity in structure was less clear. Cognitive processes however, and the nature of the children's reasoning were clarified by the method of exploration used. This was particularly fruitful for providing insight into the difficulties children may have. The findings thus contribute to understanding with a view toward furthering concept development in children with emotional and behavioral difficulties.
Adolescent↗
A screening test for modified hemoglobin blood substitutes before clinical use: based on C3a complement activation in human plasma.
Modified hemoglobin preparations may potentially cause hypersensitivity and anaphylactic reactions, antibody-antigen reactions and other problems. Unfortunately response in animal safety studies may not reflect the same response in human. The next best test before clinical trial in human may the use of human plasma in-vitro. This paper present an in-vitro procedure based on complement activation (C3a) of human plasma. The procedure involves collecting heparinised blood and separating the plasma and freezing the heparinised plasma at -70 degrees C until use. Each 100 lambda of control or test samples is added to 400 lambda of this plasma. This is incubated at 37 degrees C, 60 rpm for 1 hour, then added to EDTA saline to stop the reaction and stored at -70 degrees C until analysed by standard radioimmunoassay for C3a. (C3 measurement is not sensitivity enough). Using the screening test procedure described above, C3a levels (ng/ml) in plasma were: control, 1,980 +/- 280; Zymosan, 20,000; Hemoglobin preparation A, 2,227 +/- 617; Hemoglobin preparation B, 4,967 +/- 153; A 75% + B 25%, 3,967 +/- 270; A 50% + B 50%, 4,553 +/- 517; A 25% + B 75%, 4,920 +/- 430. Hemoglobin preparation A did not cause significant increases in C3a complement activation. Hemoglobin preparation B caused significant increase in C3a complement activation. Serial dilution of Hemoglobin preparation B in Hemoglobin preparation A continued to cause the same degree of C3a complement activation. This is not due to C3 exhaustion because Zymosan resulted in C3a of greater than 20,000ng/ml. This appears to show that this screening test can detect complement activation even at low concentrations of the hemoglobin preparation.(ABSTRACT TRUNCATED AT 250 WORDS)
Blood Substitutes↗
Genome juggling by transposons: Tam3-induced rearrangements in Antirrhinum majus.
Transposable elements are well known for their ability to generate large- and small-scale rearrangements of the sequences flanking their insertion sites. These include deletions, inversions, and duplications. Tam3, a transposon from the Snapdragon (Antirrhinum majus), is highly active in the generation of such rearrangements. We have analysed a number of Tam3-induced rearrangements at the nivea (niv) locus by Southern blotting, cloning, and sequence determination. The data obtained from these analyses have led to an understanding of the mechanisms by which these complex alleles were formed. We have shown that the primary rearrangements usually occur without excision of the element and therefore result from aberrant transposition attempts. Subsequent rearrangements may occur on excision of the element. Finally, we suggest how the analysis of such rearrangements may not only provide information about Tam3 transposition but also show how transposon-induced rearrangements may influence the structure and function of the genome as a whole.
Base Sequence↗
Activity of the transposon Tam3 in Antirrhinum and tobacco: possible role of DNA methylation.
The transposon Tam3 from Antirrhinum majus can transpose in a heterologous host (Nicotiana tabacum); thus the element is autonomous, probably encoding the specific information required for its own transposition. In transgenic tobacco Tam3 rapidly becomes methylated at its ends whilst adjacent flanking sequences remain hypomethylated. This methylation may account for our failure to detect Tam3 transposition in the progeny of transgenic tobacco. Treatment with the inhibitor of cytosine methylation, 5 aza-cytosine appeared to induce transposon related activity at a low level. In Antirrhinum methylation also appears to be associated with inactivation of Tam3 copies.
DNA↗
Molecular analysis of a transposon-induced deletion of the nivea locus in Antirrhinum majus.
The transposable element Tam3 of Antirrhinum majus is capable of causing large-scale chromosomal restructuring. It induced a large deletion at the nivea locus, to produce the allele niv-:529. The deletion removed the entire nivea coding region while the element remains intact with the potential to induce further rearrangements. Genetic experiments showed that the endpoint of the deletion (called x) is closely linked to nivea. The DNA sequences of niv-:529, a genomic excision of Tam3 from niv-:529, and the original genomic position of x have been determined. These data suggest that the deletion could have resulted from an abortive transposition or through breakage and religation.
Alleles↗
Similar-sequence and similar-structure in retarded and non-retarded children's development.
Three questions important in relation to the developmental-difference controversy were addressed. The first, to what extent do retarded and non-retarded children show a similar sequence in their development of concepts, was answered using scalogram analyses which supported a common order of acquisition of conservation concepts when intermediate as well as conservation and non-conservation categories were used. There was a high degree of similarity in sequence within as well as between attributes. The second question, how far does the similar-structure hypothesis hold, was answered in the terms set by the developmental theorists. Multiple regression analyses and comparisons of mean mental ages for each of the conservation subgroups supported the similar-structure hypothesis. Non-retarded and retarded children with no known organic condition revealed similar structures. The third question concerned findings of volume conservation in retarded children and how these might be interpreted. It is argued that recognition of conservation in displacement volume tasks need not imply a generalised stage of formal operations nor be interpreted in terms of ceiling in development. Overall the findings have implications for ordering and providing appropriate levels of experiences for retarded children without assuming fixed limits in their development.
Adolescent↗
The development of conservation concepts in children with visual impairment.
The investigation was the last in a series examining similarity of sequence and structure in the development of children with different handicapping conditions. It focused on the development of conservation concepts by children who were visually impaired but not blind. Similarity in order of acquisition of conservation concepts for visually impaired and sighted children was found and was supported by scalogram analyses yielding very high coefficients of reproducibility. Similarity in structure or level of understanding of conservation was also evident for these groups of children at comparable chronological ages and was supported by multiple regression analyses. There was no evidence of delay in the visually impaired children's development of conservation concepts.
Adolescent↗
Artificial cells in medical applications with emphasis on hemoperfusion in aluminium removal and cross-over control clinical trial of reduced time hemoperfusion-hemodialysis.
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Adult↗