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Biomedical subjects

T E Buultjens

Publications and source records attributed to T E Buultjens.

9 recordsLinked to original sources
PubMed2000

Outer membrane protein shifts in biocide-resistant Pseudomonas aeruginosa PAO1.

Benzisothiazolone (BIT), N-methylisothiazolone (MIT) and 5-chloro-N-methylisothiazolone (CMIT) are highly effective biocidal agents and are used as preservatives in a variety of cosmetic preparations. The isothiazolones have proven efficacy against many fungal and bacterial species including Pseudomonas aeruginosa. However, some species are beginning to exhibit resistance towards this group of compounds after extended exposure. This experiment induced resistance in cultures of Ps. aeruginosa exposed to incrementally increasing sub-minimum inhibitory concentrations (MICs) of the isothiazolones in their pure chemical forms. The induced resistance was observed as a gradual increase in MIC with each new passage. The MICs for all three test isothiazolones and a thiol-interactive control compound (thiomersal) increased by approximately twofold during the course of the experiment. The onset of resistance was also observed by reference to the altered presence of an outer membrane protein, designated the T-OMP, in SDS-PAGE preparations. T-OMP was observed to disappear from the biocide-exposed preparations and reappear when the resistance-induced cultures were passaged in the absence of biocide. This reappearance of T-OMP was not accompanied by a complete reversal of induced resistance, but by a small decrease in MIC. The induction of resistance towards one biocide resulted in the development of cross-resistance towards other members of the group and the control, thiomersal. It has been suggested that the disappearance of T-OMP from these preparations is associated with the onset of resistance to the isothiazolones in their Kathon form (CMIT and MIT).

Bacterial Outer Membrane Proteins↗
PubMed1988

Tissue and species conservation of the vertebrate and arthropod forms of the low molecular weight (16-18000) proteins of gap junctions.

Gap junctions have been isolated from four murine tissues, from rat and Xenopus laevis liver, and from Nephrops norvegicus (Norway lobster) hepatopancreas. The preparations of gap junctions from each vertebrate tissue contain a single major protein, Mr 16,000, and those from Nephrops hepatopancreas a protein, Mr 18,000. Immunocytochemical studies using affinity-purified antibodies raised against gap junctions from Nephrops show the junctional origin of the 18k protein. Immunological studies using Western blotting and biochemical studies using tryptic peptide mapping show no significant differences between the 16k junctional proteins of mouse and hence provide no evidence of tissue variation. These studies also suggest that the mouse, rat, and Xenopus 16k proteins and the Nephrops 18k protein share some common structural features.

Animals↗
PubMed1988

Inhibition of dye-coupling in Patella (Mollusca) embryos by microinjection of antiserum against nephrops (Arthropoda) gap junctions.

Antiserum raised against Nephrops gap junctions was injected into single cells of the 2-, 4-, 8-, 16-, and 32-cell stage of the Patella vulgata embryos. The pattern of junctional communication by iontophoresis of Lucifer Yellow CH was tested at the 32-cell stage. The results show that the normal pattern of dye-coupling at the 32-cell stage is disrupted in greater than 65% of embryos previously injected with antisera. In contrast, less than 15% of embryos injected with preimmune serum exhibited disrupted patterns of dye-coupling. Up to the late 32-cell stage no effect of the antiserum on the pattern of cleavage was detected. This antiserum may provide a powerful tool to investigate the role of junctional communication in later stages of development of Patella embryos.

Animals↗
PubMed1987

Molecular structure of the gap junctional channel.

The proteins in various gap junctional preparations from rodent liver have been analysed by two-dimensional peptide mapping and immunoblotting. Only the protein of relative molecular mass (Mr) 16,000 (16K) is found in all gap junctional isolates, and it is unrelated to the 27K protein. The absence of the 27K protein and any of its fragments from trypsin-treated preparations suggests that this protein does not directly contribute to gap junctional structure. Peptide mapping and immunoblotting of the 16K proteins isolated from various tissues and species and of the arthropod 18K protein present in gap junctional preparations from Nephrops norvegicus show that these proteins constitute a family of related junctional proteins. A site-specific antiserum raised against the N-terminal octapeptide of the 16K protein from mouse liver cross-reacts with all 16K and 18K forms of the junctional protein so far tested, suggesting that this particular antigenic determinant is highly conserved. Immuno-localization studies show that the N-terminus is most likely located on the cytoplasmic aspect of the junction and is available to Pronase digestion.

Animals↗
PubMed1984

Isolation and characterisation of arthropod gap junctions.

Gap junctions have been isolated from the hepatopancreas of the crustacean arthropod, Nephrops norvegicus (Norway lobster). SDS-PAGE of these preparations shows two major protein bands, mol. wt. 18 000 (18 K) and mol. wt. 28 000 (28 K). The 18-K and 28-K proteins are interconvertible, cannot be distinguished by two dimensional tryptic and chymotryptic peptide mapping, and therefore appear to be different (most likely monomeric and dimeric) forms of the same protein. The protein can also aggregate to higher multimeric forms mol. wt. 38 000 (presumed trimer), and mol. wt. 52 000 (presumed tetramer). The buoyant density of the isolated gap junctions in continuous potassium iodide gradients is 1.260 g/cm. The junctions are progressively solubilized in increasing SDS concentrations, mostly between 0.1% and 0.2% SDS, and this is accompanied by the release of the 18-K and 28-K forms of the junctional protein. The Nephrops hepatopancreas 18-K junctional protein has antigenic determinants in common with the vertebrate 16-K junctional protein as shown by cross-reactivity with two different affinity purified antibody preparations. However, no detectable similarity can be seen between the major I-labelled tryptic and chymotrytpic peptides of the Nephrops hepatopancreas 18-K protein and the mouse liver 16-K protein.

Journal Article↗
PubMed1982

The gap junctional channel.

Two distinct forms of intercellular communication have been found in animal tissues, one using the familiar, trans-membrane, extracellular route and the other using an entirely intracellular route. The intracellular route depends on specialized, permeable (gap) junctions which form at areas of contact between adjacent cells. The junctions contain aqueous channels which directly link the cytoplasms of the coupled cells. Small ions and molecules pass through these channels and move freely between all cells in coupled populations. The structural protein which forms the gap junctional channel has been isolated and characterized. It has an apparent M.Wt. of 16,000 and readily forms multimeric structures. In the membrane, six protein subunits surround the central aqueous pore. Addition of retinoic acid to cells appears to close the junctional channels. This effect of retinoic acid on the junctional pathway of intercellular communication may explain some of its biological activities.

Animals↗
PubMed1977

Adhesive selectivity is exhibited in vitro by cells from adjacent tissues of the embryonic chick retina.

Cells from anatomically remote organs of developing embryos do not normally encounter one another. If intercellular adhesive selectivity has a role in determining or maintaining the position of cells in organs, it should be exhibited between cells which are found in close proximity within a single organ. To test this hypothesis, a collecting cell-sheet assay for intercellular adhesive selectivity has been applied to cells from 3 layers of the retina of the embryonic chick. The finding of a modest degree of selectivity of adhesion between cells from the neural retina and choroid supports the hypothesis. The observed selective low adhesiveness for self of the upper surface of pigmented retina epithelium emphasizes the likely morphogenetic significance of the topographical distribution of intercellular adhesiveness.

Animals↗