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Biomedical subjects

A J Mort

Publications and source records attributed to A J Mort.

29 records · Page 2Linked to original sources
PubMed1989

Serum antibody response to carbohydrate antigens of Pasteurella haemolytica serotype 1: relation to experimentally induced bovine pneumonic pasteurellosis.

The antibody responses to the capsular carbohydrate (CC) purified from Pasteurella haemolytica serotype 1 were determined by an ELISA, using 135 sera from 6 calves vaccinated with phosphate-buffered saline solution, formalin-killed P haemolytica bacterins, live P haemolytica, or an extract of P haemolytica referred to as carbohydrate-protein subunit (CPS). Calves vaccinated with live P haemolytica, bacterins, or CPS developed serum antibodies to CC. Bacterins containing Freund incomplete adjuvant or Freund complete adjuvant induced higher antibody responses than did bacterins containing aluminum hydroxide. In 4 of 6 experiments, high antibody responses to CC were significantly (P less than 0.05) correlated with resistance to transthoracic challenge exposure with P haemolytica. When calves were challenge exposed with a dose of P haemolytica that was 4.5 times greater than the standard challenge exposure dose or when calves that had been vaccinated with CPS were challenge exposed, antibody responses did not significantly (P greater than 0.05) correlate with resistance to challenge exposure. The amount of serum antibodies to CPS increased significantly (P less than 0.05) when calves were vaccinated with live or killed P haemolytica or with CPS, compared with that in calves given saline solution. In 5 of 6 experiments, correlation between high antibody responses and resistance to challenge exposure was significant (P less than 0.05). The correlation between those variables was not significant (P less than 0.07) for CPS-vaccinated calves. In the ELISA, treatment of CPS with sodium m-periodate, to oxidize periodate-sensitive carbohydrate epitopes, failed to markedly alter the antibody response to CPS.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Characterization of root hair cell walls as potential barriers to the infection of plants by rhizobia : the carbohydrate component.

The sugar compositions of root hairs of a variety of plant species were determined. Root hairs of legumes had very similar compositions, whereas those of different families varied widely. Only approximately 50% of the weight of the root hairs of legumes could be accounted for by sugar. Up to 80% of the weight of root hairs from other sources could be accounted for by sugars. Protein made up 5 to 8% of the weight of root hairs of dicots but only 1.3% in corn. Comparison between cell walls from various root cell types within legumes showed that the polysaccharide compositions of root epidermal, root hair, and root cortical cells were very similar. Cotton root hairs were markedly different from walls of mesophyll and epidermal cells of cotyledons from cotton.

Journal Article↗
PubMed1987

Reexamination of the presence and linkage of 3-hydroxybutyryl substituents in the acidic capsular polysaccharide of Rhizobium trifolii 0403.

We resolved previous conflicting results concerning the presence of 3-hydroxybutyryl substituents on the extracellular acidic polysaccharide from Rhizobium trifolii 0403. These substituents were indeed present in the polysaccharide and in the oligosaccharide fragments obtained by hydrogen fluoride solvolysis of the extracellular and capsular polysaccharides of the bacteria grown on plates. The 3-hydroxybutyrate substituent could be removed from the polysaccharide by 10 mM sodium deuteroxide without evidence of elimination, indicating that this substituent was ester linked.

3-Hydroxybutyric Acid↗
PubMed1986

Location and identity of the acyl substituents on the extracellular polysaccharides of Rhizobium trifolii and Rhizobium leguminosarum.

The basic structures of the extracellular polysaccharides of Rhizobium leguminosarum and Rhizobium trifolii were found to be identical, but their acylation patterns differ. Liquid hydrogen fluoride at -40 degrees degrades the two polysaccharides to a series of oligosaccharides representing the repeating units of the polysaccharides and their higher homologs. At -23 degrees, it degrades the polymers to a mixture of oligosaccharides from which a tetrasaccharide constituting a unit of the backbone of the polysaccharide, and a trisaccharide representing all but the non-reducing terminus of the side chain, could be readily purified. The location and identity of the acyl substituents were determined by 1H-n.m.r. spectroscopy, methylation analysis, and f.a.b. mass spectrometry. The unusual substituent D-3-hydroxybutanoate was found esterified to O-3 of a terminal 4,6-O-pyruvic acetylated D-galactose in both strains of R. leguminosarum, and in one of the three strains of R. trifolii tested. All of the strains tested contained a 3-O-acetyl substituent on the (1----4)-beta-D-glucopyranosyl residues in the backbone of the polysaccharide. Only the R. leguminosarum polysaccharides contained a combination of 2- and 3-O-acetyl groups on the branching sugar of the backbone of the polymer.

Acylation↗
PubMed1983

Recovery of methylated saccharides from methylation reaction mixtures using Sep-Pak C18 cartridges.

Methylated oligo- and polysaccharides can be rapidly and efficiently separated from the reaction mixtures used to methylate them using a Waters C18 Sep-Pak cartridge. The methylated saccharides are retained by the Sep-Pak as the reaction mixture, diluted fivefold with water, is passed through. Extraneous materials are washed away with water, and then the sugars are eluted with 50 or 100% methanol. Samples of up to approximately 4 mg can be accommodated. Extremely small samples (10-50 micrograms) can also be purified.

Chromatography, Liquid↗
PubMed1982

Application of two new methods for cleavage of polysaccharides into specific oligosaccharide fragments. Structure of the capsular and extracellular polysaccharides of Rhizobium japonicum that bind soybean lectin.

The extracellular polysaccharide produced by the bacterium Rhizobium japonicum has been implicated in the recognition between symbionts which takes place in the association of R. japonicum with soybean. The complete primary structure of the polysaccharide produced by R. japonicum strain 3I1b 138 has been determined by a combination of conventional and unconventional methods. The polymer contains glucose, mannose, and galacturonic acid in the molar ratio of 2:1:1 and contains a varying proportion of galactose and 4-O-methylgalactose, the sum of these two being equivalent to the amount of mannose (Mort, A. J., and Bauer, W. D. (1980) Plant Physiol, 66, 158-163). The polymer was specifically degraded and its galacturonic acid residues by treatment with lithium in ethylenediamine to a tetrasaccharide. By sequential specific glycosidase hydrolysis and methylation analysis the tetrasaccharide was shown to have Structure 1: (formula: see text). Anhydrous liquid hydrogen fluoride at -23 degrees C degraded the polymer to a trisaccharide and monosaccharides. The galactose and 4-O-methylgalactose released by the HF as monosaccharides were found to be partially acetylated. By 1H NMR spectrometry and methylation analysis the trisaccharide was found to have Structure 2: (formula: see text). From the composition and the structural analyses of the tetra- and trisaccharides produced in high yields by specific degradations of the polysaccharide, the polymer is deduced to have a pentasaccharide repeating unit with Structure 3: (formula: see text).

Carbohydrate Conformation↗
PubMed1980

Composition of the Capsular and Extracellular Polysaccharides of Rhizobium japonicum: CHANGES WITH CULTURE AGE AND CORRELATIONS WITH BINDING OF SOYBEAN SEED LECTIN TO THE BACTERIA .

The chemical compositions of the capsular and extracellular polysaccharides of two strains of Rhizobium japonicum (311b 138 and 110) have been determined and correlated as a function of culture age with the ability of the bacteria from which they were obtained to bind soybean seed lectin.Each of the polysaccharides contains approximately constant amounts of mannosyl, glucosyl, and galacturonosyl residues in a molar ratio of 1:2:1. In addition they contain variable amounts of galactosyl and 4-O-methyl galactosyl residues. The total of galactose plus 4-O-methyl galactose, however, is constant and equivalent to the amount of mannose, indicating that the 4-O-methyl galactose residues arise by methylation of galactose residues in the polysaccharides. In both strains the proportion of galactose to methyl galactose is considerably greater in the polysaccharide from bacteria which do bind lectin than in the polysaccharide from bacteria which do not bind lectin.In addition to the changes in polysaccharide composition, there is a reduction of about 50% in the percentage of cells which are encapsulated as the cultures mature from early to late log phase. Since only capsulated cells bind lectin, the combination of the change in capsular composition and loss of encapsulation is probably sufficient to account for the loss of lectin binding capacity during growth of cultures of Rhizobium japonicum 311b 138 and 110.

Journal Article↗
PubMed1978

A new approach to the structural determination of glycoproteins and polysaccharides: anhydrous HF solvolysis.

From experiments with glycoproteins containing the glycopeptide linkages, arabinose-O-hydroxyproline and galactose-O-serine (plant cell wall glycopeptides), N-acetylgalactosamine-O-serine/threonine (pig submaxillary mucin), and N-acetyl-glucosamine-N-asparagine (fetuin), it is apparent that anhydrous liquid HF, a reagent commonly used by snythetic peptide chemists for the complete removal of protecting groups from synthetic peptides, cleaves the O-glycosidic linkages of neutral sugars in 1 hr at 0 degrees C, and the O-glycosidic linkages of amino sugars in 3 hr at 23 degrees C. The N-glycosidic linkage of N-acetylglucosamine to asparagine is not cleaved under any conditions that have been tested. Sodium dodecyl sulfate gel electrophoresis of bovine serum albumin treated in HF does not show any degradation of peptide bonds. Some relatively stable enzymes (lysozyme and RNase) have been shown by others to retain most of their enzymic activity after short treatment (1 hr at 0 degrees C) in HF. With the specificity of HF at 0 degrees C for neutral sugars it should be possible to generate di- or trisaccharides in high yield from polysaccharides containing both neutral and amino sugars with neutral sugars as the reducing termini.

Animals↗
PubMedDate not supplied

"SpectraGraph" and "SpectraSort": mass spectral display and interpretation software for the Macintosh.

Two computer programs entitled "SpectraGraph" and "SpectraSort" have been written for te Apple Macintosh. SpectraGraph allows graphical display, manipulation, storage, and printing of an input mass spectrum list that has been imported from a mass spectrometer or entered manually. SpectraGraph gives the user the ability to display, normalize, and multiply different mass ranges, annotate peaks, and perform various other operations on the spectral display. Also the mass spectrum and other graphics may be copied to and from other Macintosh application documents. SpectraSort has been developed to aid in the interpretation of mass spectra, particularly those of biopolymers, by calculating the mass differences between peaks in a mass spectrum. The user then has the option of matching the mass differences with masses of fragments or residues stored in several user-definable look-up tables.

Carbohydrate Sequence↗