The faeA genes from Aspergillus niger and Aspergillus tubingensis encode ferulic acid esterases involved in degradation of complex cell wall polysaccharides.

We report the cloning and characterization of a gene encoding a ferulic acid esterase, faeA, from Aspergillus niger and Aspergillus tubingensis. The A. niger and A. tubingensis genes have a high degree of sequence identity and contain one conserved intron. The gene product, FAEA, was overexpressed in wild-type A. tubingensis and a protease-deficient A. niger mutant. Overexpression of both genes in wild-type A. tubingensis and an A. niger protease-deficient mutant showed that the A. tubingensis gene product is more sensitive to degradation than the equivalent gene product from A. niger. FAEA from A. niger was identical to A. niger FAE-III (C. B. Faulds and G. Williamson, Microbiology 140:779-787, 1994), as assessed by molecular mass, pH and temperature optima, pI, N-terminal sequence, and activity on methyl ferulate. The faeA gene was induced by growth on wheat arabinoxylan and sugar beet pectin, and its gene product (FAEA) released ferulic acid from wheat arabinoxylan. The rate of release was enhanced by the presence of a xylanase. FAEA also hydrolyzed smaller amounts of ferulic acid from sugar beet pectin, but the rate was hardly affected by addition of an endo-pectin lyase.     

Metabolism of hexadecyltrimethylammonium chloride in Pseudomonas strain B1.

A bacterium (strain B1) utilizing hexadecyltrimethylammonium chloride as a carbon and energy source was isolated from activated sludge and tentatively identified as a Pseudomonas sp. This bacterium only grew on alkyltrimethylammonium salts (C12 to C22) and possible intermediates of hexadecyltrimethylammonium chloride breakdown such as hexadecanoate and acetate. Pseudomonas strain B1 did not grow on amines. Simultaneous adaptation studies suggested that the bacterium oxidized only the alkyl chain of hexadecyltrimethylammonium chloride. This was confirmed by the stoichiometric formation of trimethylamine from hexadecyltrimethylammonium chloride. The initial hexadecyltrimethylammonium chloride oxygenase activity, measured by its ability to form trimethylamine, was NAD(P)H and O2 dependent. Finally, assays of aldehyde dehydrogenase, hexadecanoyl-coenzyme A dehydrogenase, and isocitrate lyase in cell extracts revealed the potential of Pseudomonas strain B1 to metabolize the alkyl chain via beta-oxidation.     

The demonstration of phospholipids in certain cells in neurosecretory nuclei in the rat with Baker's acid haematein after fixation in glutaraldehyde-formol-calcium

Summary With Baker's acid haematein test certain ganglion cells in the brain, their processes and, at some sites, glial cells around blood vessels stain dark blue. This article describes a study of the Baker-positive cells which occur in and around the neurosecretory nuclei. By substituting formol-calcium fixation with glutaraldehyde-formol-calcium fixation shrinkage in brain tissue is completely avoided. If such fixation is used the argument that positive staining of ganglion cells with Baker's method only indicates that these are shrunken neurons can no longer be maintained. A comparative histological study, especially of Baker's technique and controlled chromation (Elftman) showed that the Baker-positive cells contain a phospholipid, probably bound to a protein, as a labile compound, which is easily lost. We found that to immobilize and localize this labile compound in the ganglion cells the technique of fixation and the pH during chromation (which should be around 3.8) are of fundamental importance. Only under these conditions is the complex sufficiently immobilized to allow of its demonstration with acid haematein. These requirements are now completely met if Baker's acid haematein technique is used. The article stresses that only prefixed and chromated frozen sections can be used for this method, thus avoiding shrinkage and non-specific staining of proteins. The modified Baker method as used by us gives constant and reproducible staining and is described in this article. The functional significance of the Baker-positive reaction in some ganglion cells in the n. s. nuclei or glial cells around blood vessels is not dealt with in this article.     

Inhibition of mitochondrial protein synthesis influences the glucocorticoid sensitivity of lymphoid cells

Inhibition of mitochondrial protein synthesis impairs the formation of the 13 polypeptides encoded on the mitochondrial genome. These polypeptides are part of enzyme complexes involved in oxidative phosphorylation. Prolonged inhibition of mitochondrial protein synthesis thus reduces the oxidative phosphorylation capacity which ultimately results in impairment of energy-requiring processes. Via a different mechanism glucocorticoid hormones also decrease the oxidative phosphorylation capacity of, e.g., lymphoid cells. The present study shows that inhibition of mitochondrial protein synthesis influences glucocorticoid-induced responses of lymphoid cells in two opposing manners. (a) It is enhanced after induction in cells with a reduced oxidative phosphorylation capacity resulting from preceding inhibition of mitochondrial protein synthesis. This can be explained by the synergistic effects of glucocorticoids and prolonged inhibition of mitochondrial protein synthesis on energy-producing processes. (b) It is counteracted when mitochondrial protein synthesis is impaired during induction of the response. The latter observation suggests that mitochondrial protein synthesis is involved in the generation of glucocorticoid-induced effects on lymphoid cells.