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M V Bell

Publications and source records attributed to M V Bell.

45 records · Page 3Linked to original sources
PubMed1983

The transport of orthovanadate and similar oxyanions in relation to salt and water transport across the isolated intestine of the common eel, Anguilla anguilla.

An intestinal preparation from the common eel (Anguilla anguilla) was characterized for both mucosal to serosal and serosal to mucosal transport of water, alanine, sodium and chloride. The preparation showed a net outflux of water and a net influx of alanine, and no net fluxes of sodium or chloride. The influxes of all four substances and the outflux of water were inhibited by ouabain, while the outfluxes of alanine, sodium and chloride were increased by ouabain. Influxes and outfluxes of the oxyanions orthovanadate, phosphate, arsenate, sulphate, selenate and chromate were measured over a range of concentrations from 10(-8) M to 10(-4) M. The entry of each anion was dependent on the mucosal concentration, not saturable within the concentration range used or competitive with chloride. There were no net fluxes of these anions and pertechnecate from solutions containing equal mucosal and serosal concentrations of the anion.

Alanine↗
PubMed1981

Effects of orthovanadate on salt and water effluxes from the gills of seawater eels, Anguilla anguilla.

Orthovanadate (5 . 10(-7) M) perfused through isolated gills at a constant rate increased the perfusion pressure by 40% but inhibited the effluxes of Na+ and Cl- by 40%. Water efflux was unaltered. Ouabain (10(-4) M) and rotenone (10(-4) M) influenced salt and water effluxes in the same way but did not alter perfusion pressures. Orthovanadate (10(-5) M) perfused at constant rate increased the pressure nearly 2.5-fold; under these conditions effluxes of Na+, Cl- and H2O were all increased approximately 2.5-fold.

Anguilla↗
PubMed1981

The uptake from fresh water and subsequent clearance of a vanadium burden by the common eel (Anguilla anguilla).

The uptake of 48V vanadium from a solution of 10(-5) M 48V-orthovanadate by fresh-water elvers and the subsequent depletion of the vanadium burden was studied. At the end of the 8-week loading period, the levels of 48V were still increasing in the liver, kidney, bone and carcase. The uptake rate for the whole fish over the 8-week period was 760 pg atom/h/100 g body wt and the depletion rate over the following 5 weeks in clean water was about one tenth of this. Liver contained the highest amount of 48V at the end of the 8-week loading period, calculated as equivalent to 1.1 x 10(-4) g atom V/kg wet wt, and this level was unchanged at the end of the 5-week depletion period. Less than 1% of the carcase 48V was present in the fraction of MW under 2000.

Anguilla↗
PubMed1979

The partial purification of sodium-plus-potassium ion-dependent adenosine triphosphatase from the gills of Anguilla anguilla and its inhibition by orthovanadate.

1. (Na+ +K+)-dependent ATPase was partially purified from eel gills by a procedure in which the microsomal fraction of crude preparations of chloride cells was selectively extracted with sodium dodecyl sulphate. 2. The microsomal specific activity was increased 2-fold during optimal treatment with detergent. 3. The final preparation (56% pure) had a specific activity of 341 mumol of ATP hydrolysed/h per mg of protein and a turnover number of 3560 min-1. The number of ouabain-binding sties equalled the number of sites phosphorylated by ATP. 4. Both sodium orthovanadate and ouabain inhibited the purified preparation more than the microsomal fraction, vanadate being more effective on an equimolar basis than ouabain. 5. Inhibition by orthovanadate was not enhanced at 28 mM-as compared with 1mM-MgCl2 and was not reversed by beta-adrenergic agonists (cf. Josephson & Cantley (1977) Biochemistry 16, 4572--4578). 6. Of various other metallic oxyanions tested only niobate proved an effective inhibitor of the enzyme although this anion was less effective than orthovanadate. 7. Orthovanadate partially inhibited phosphorylation of the enzyme by ATP in the presence of 28 mM-MgCl2.

Adenosine Triphosphate↗
PubMed1978

The purification and properties of urocanase from Pseudomonas testosteroni.

Urocanase (urocanate hydratase, EC 4.2.1.49) purified from Pseudomonas testosteroni has a mol.wt. of 118000 determined by sedimentation-equilibrium analysis. Ultracentrifugation in 6M-guanidine hydrochloride and polyacrylamide-gel electrophoresis in sodium dodecyl sulphate show that the enzyme consists of two identical or very similar subunits. It is, like urocanase isolated from other sources, inhibited by reagents that react with carbonyl groups. Although urocanase from Ps. testosteroni is strongly inhibited by NaBH4, no evidence could be obtained for the presence of covalently bound 2-oxobutyrate as a prosthetic group; this is in contrast with findings elsewhere for urocanase from Pseudomonas putida. Urocanase from Ps. testosteroni does not contain pyridoxal 5'-phosphate as a coenzyme and in this respect is similar to all urocanases studied in purified form.

Borohydrides↗
PubMed1977

The activation of sodium-plus-potassium ion-dependent adenosine triphosphatase from marine teleost gills by univalent cations.

The apparent affinity constants for the binding of Cs+, Rb+, K+, Li+, Tl+ and NH4+ to (Na+ + K+)-dependent adenosine triphosphatase from teleost gills were measured and the values discussed in terms of the ion-selectivity isotherm described by Eisenman & Krasne (1975) [in MTP International Review of Science: Biochemistry Series One (Fox, C.F., ed.), vol. 2, pp. 27--59, Butterworths University Park Press, Baltimore]. The ion selectivity of the present enzyme is remarkably similar to that from nerve and brain.

Adenosine Triphosphatases↗
PubMedDate not supplied

Linkage analysis in the fragile X syndrome using multiple distal Xq polymorphic DNA markers.

Linkage data using the polymorphic loci F9, DXS105, DXS98, DXS52, DXS15, and F8 and the DNA probe 1A1 are presented from 14 families segregating for fragile X [fra(X)] syndrome. Recombination fractions corresponding to the maximum LOD scores obtained by two-point linkage analysis suggest that DXS98 (Zmax = 3.23, theta = 0.0) and DXS105 (Zmax = 2.09, theta = 0.0) are the closest markers proximal to FRAXA and that DXS52 is the closest distal marker (Zmax = 3.55, theta = 0.16). FRAXA is located within a 25 cM interval between F9 and DXS52, coincident with DXS98, on multipoint linkage analysis. Phase-known three way crossover information places F8 outside the cluster (DXS52, DXS15, 1A1). Confidence limits for the markers DXS98 and DXS52 are relatively wide (0.0-0.15 and 0.06-0.31, respectively), but when used in combination with cytogenetic examination offer improved carrier detection in comparison with cytogenetic analysis alone.

Blotting, Southern↗
PubMedDate not supplied

Mapping of a cerebellar degeneration related protein and DXS304 around the fragile site.

We have localized the gene encoding a cerebellar degeneration related (CDR) protein to a region proximal to the fragile site close to DXS98 and DXS105. This gene is polymorphic with the enzyme RsaI and therefore also provides a new genetic marker in this region. We have refined the localization of the locus DXS304 distal to the breakpoint in a patient suffering from Hunter disease. This confirms the localization of DXS304 distal to the fragile site previously suggested by linkage studies and localizes the fragile X mutation to a relatively small region between the Hunter breakpoint and the breakpoint in another hybrid B17.

Base Sequence↗