Analysis of cellular fatty acids by gas chromatography as a tool in the identification of medically important coryneform bacteria

The fatty acid methyl esters of nineteen unidentified pathogenic coryneform bacteria were analysed by gas-liquid chromatography and the resulting profiles were compared with those of type or reference strains of possibly related species, namely Caseobacter polymorphus, Corynebacterium bovis, C. diphtheriae, C. xerosis and Rhodococcus equi. All of the strains had distinct fatty acid profiles but most of them conformed to a general pattern, with high levels of octadecanoic acids and only trace amounts of 10-methyl octadecanoic acid (tuberculostearic acid). These profiles were very similar to those from C. diphtheriae and C. xerosis but could be differentiated from C. bovis, Cas. polymorphus, R. equi and two unidentified pathogenic strains which had significantly higher levels of tuberculostearic acid.     

Numerical and chemical classification ofStreptosporangium and some related actinomycetes

One hundred and seventeen streptosporangia from soil were compared with marker strains of the familyStreptosporangiaceae for many phenotypic properties. The data were examined using the Jaccard, pattern and simple matching coefficients with clustering achieved using average, complete and single linkage algorithms. Particular confidence was placed in the product of the pattern, average linkage analysis given the sharp definition of aggregate groups and clusters and a combination of low test error and high cophenetic correlation values. The test strains were assigned to five aggregate groups that were equated with the generaStreptosporangium (group A),Microbispora (group B),Planobispora andPlanomonospora (Group C),Kutzneria (neéStreptosporangium viridogriseum (group D), andMicrotetraspora (group E). The streptosporangia, both isolates and marker strains, were assigned to 5 major, 7 minor and 18 single membered clusters. Representative streptosporangia examined for chemical markers were characterised by the presence ofmeso-diaminopimelic acid in whole-organism hydrolysates, complex mixtures of straight- and branched chain fatty acids, di- and tetrahydrogenated menaquinones as predominant isoprenologues, and complex polar lipid patterns containing diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylmethylethanolamine, phosphatidylinositol, phosphatidylinositol mannosides and uncharacterised components. The chemical and numerical data support the taxonomic integrity of the validly described species ofStreptosporangium and suggest that the genus is markedly underspeciated.     

Effect of neurotensin on pancreatic function in man

The effect of neurotensin on submaximally-stimulated hepatobiliary and pancreatic secretion was studied in 6 healthy subjects. An intravenous infusion of neurotensin 1.4 ± 0.3 pmol/kg/min, designed to reproduce plasma neurotensin immunoreactivity levels within the physiological range, produced a significant increase in pancreatic bicarbonate output. Plasma concentrations of pancreatic polypeptide rose by 83 ± 16 pmol/l and were associated with a small reduction in trypsin, but no significant change in bilirubin outputs.     

Effect of Metalaxyl on the incidence and severity of Pearl millet downy mildew disease in Northern Nigeria

Pearl millet downy mildew (DM) incidence, severity and yield losses of two pearl millet varieties (local and improved) due to the disease were determined in the field. Significant differences in the disease incidence and severity were recorded in the plots sown with metalaxyl-treated seeds and those sown with non-treated seeds, indicating the efficacy of the fungicide on the fungus. Yield losses due to non-treatment of seeds with metalaxyl was 40.88 and 45.39% in a local variety and 43.00 and 18.60% in an improved variety in the 2000 and 2001 cropping seasons respectively. Significant differences between plots sown with metalaxyl-treated and those sown with non-treated seeds were obtained for other yield components such as 1000-grains weight, panicle length and weight.     

Effect of temperature on the saccharide composition obtained after alpha-amylolysis of starch

The hydrolysis of starch to low-molecular-weight products (normally characterised by their dextrose equivalent (DE), which is directly related to the number-average molecular mass) was studied at different temperatures. Amylopectin potato starch, lacking amylose, was selected because of its low tendency towards retrogradation at lower temperatures. Bacillus licheniformis alpha-amylase was added to 10% [w/w] gelatinised starch solutions. The hydrolysis experiments were done at 50, 70, and 90 degrees C. Samples were taken at defined DE values and these were analysed with respect to their saccharide composition. At the same DE the oligosaccharide composition depended on the hydrolysis temperature. This implies that at the same net number of bonds hydrolysed by the enzyme, the saccharide composition was different. The hydrolysis temperature also influenced the initial overall molecular-weight distribution. Higher temperatures led to a more homogenous molecular weight distribution. Similar effects were observed for alpha-amylases from other microbial sources such as Bacillus amyloliquefaciens and Bacillus stearothermophilus. Varying the pH (5.1, 6.2, and 7.6) at 70 degrees C did not significantly influence the saccharide composition obtained during B. licheniformis alpha-amylase hydrolysis. The underlying mechanisms for B. licheniformis alpha-amylase were studied using pure linear oligosaccharides, ranging from maltotriose to maltoheptaose as substrates. Activation energies for the hydrolysis of individual oligosaccharides were calculated from Arrhenius plots at 60, 70, 80, and 90 degrees C. Oligosaccharides with a degree of polymerisation exceeding that of the substrate could be detected. The contribution of these oligosaccharides increased as the degree of polymerisation of the substrate decreased and the temperature of hydrolysis increased. The product specificity decreased with increasing temperature of hydrolysis, which led to a more equal distribution between the possible products formed. Calculations with the subsite map as determined for the closely related alpha-amylase from B. amyloliquefaciens reconfirmed this finding of a decreased substrate specificity with increased temperature of hydrolysis. Copyright 1999 John Wiley & Sons, Inc.     

POCUS: mining genomic sequence annotation to predict disease genes

Here we present POCUS (prioritization of candidate genes using statistics), a novel computational approach to prioritize candidate disease genes that is based on over-representation of functional annotation between loci for the same disease. We show that POCUS can provide high (up to 81-fold) enrichment of real disease genes in the candidate-gene shortlists it produces compared with the original large sets of positional candidates. In contrast to existing methods, POCUS can also suggest counterintuitive candidates.