Olga Salcher

Atrial but Not Ventricular Fibrosis in Mice Expressing a Mutant Transforming Growth Factor-β1 Transgene in the Heart

Increased transforming growth factor (TGF)-beta(1) activity has been observed during pathologic cardiac remodeling in a variety of animal models. In an effort to establish a causal role of TGF-beta(1) in this process, transgenic mice with elevated levels of active myocardial TGF-beta(1) were generated. The cardiac-restricted alpha-myosin heavy chain promoter was used to target expression of a mutant TGF-beta(1) cDNA harboring a cysteine-to-serine substitution at amino acid residue 33. This alteration blocks covalent tethering of the TGF-beta(1) latent complex to the extracellular matrix, thereby rendering a large proportion (>60%) of the transgene-encoded TGF-beta(1) constitutively active. Although similar levels of active TGF-beta(1) were present in the transgenic atria and ventricles, overt fibrosis was observed only in the atria. Surprisingly, increased active TGF-beta(1) levels inhibited ventricular fibroblast DNA synthesis in uninjured hearts and delayed wound healing after myocardial injury. These data suggest that increased TGF-beta(1) activity by itself is insufficient to promote ventricular fibrosis in the adult mouse ventricle.

Trichococcus flocculiformis gen. nov. sp. nov. A new gram-positive filamentous bacterium isolated from bulking sludge

SummaryA new gram-positive filamentous bacterium with coccoid cells has been isolated from bulking sludge from five sewage treatment plants in West-Germany. The characteristics of five strains are described. Their fatty acids and cell wall composition are similar to the Streptococcaceae and they mainly degrade monomeric and dimeric carbon sources. They are classified as a new genus and species of the family Streptococcaceae: Trichococcus flocculiformis gen. nov. sp. nov.

Regulation of Phospho-2-keto-3-deoxy-heptonate Aldolase (DAHP Synthase) and Anthranilate Synthase of Pseudomonas aureofaciens

Phospho-2-keto-3-deoxy-heptonate aldolase (DAHP synthase) of Pseudomonas aureofaciens ATCC 15926 was inhibited by L-tyrosine. The inhibition was competitive with erythrose 4-phosphate as the varied substrate but non-competitive with respect to phosphoenolpyruvate. Anthranilate synthase was inhibited by L-tryptophan. The inhibition was competitive with respect to chorismate but non-competitive with L-glutamine or NH4+ as the varied substrate. DAHP synthase and anthranilate synthase were not repressed when aromatic amino acids were included in the growth medium. In bacteria grown in the presence of L-phenylalanine, the anthranilate synthase activity was enhanced about threefold compared with the control. Similar results were obtained with the mutant strain P. aureofaciens ACN, which produces increased amounts of pyrrolnitrin.

Metabolism of tryptophan by Pseudomonas aureofaciens and its relationship to pyrrolnitrin biosynthesis.

Studies on the metabolism of tryptophan in Pseudomonas aureofaciens ATCC 15926 revealed different metabolic routes for the L- and D-isomer besides the biosynthetic pathway for pyrrolnitrin synthesis. L-Tryptophan catabolism follows the aromatic route via anthranilic acid. Tryptophan 2,3-dioxygenase were induced by L-tryptophan. Kynureninase and anthranilate 1,2-dioxygenase were induced by L-tryptophan, L-kynurenine and anthranilic acid. Anthranilate 1,2-dioxygenase was absent from a mutant strain of P. aureofaciens ATCC 19526 which produced about 30-fold increased amounts of pyrrolnitrin. The Km values of tryptophan 2,3-dioxygenase and kynureninase did not differ substantially between the two strains. Kynurenine 3-monooxygenase, 3-hydroxyanthranilate 3,4-dioxygenase, tryptophanase and indolyl-3-alkane alpha-hydroxylase activities were not detected. D- and L-tryptophan were converted to indole-3-acetic acid. This additional catabolic pathway was well as tryptophan racemase activity was constitutive and present in both strains.

The nutritional pattern of filamentous bacteria isolated from bulking sludge

Summary The nutritional pattern of five groups of filamentous bacteria isolated from bulking sludge is described. Four groups, two with gliding motility, comprised Gram-negative, rod-shaped, sheathed bacteria. The Gram-positive, coccoid bacteria of group V formed sheathless filaments. The metabolism of carbohydrates, lipids, organic acids and proteins in groups I-V has been examined. Group I isolates degraded polymeric substrates, while the others, especially group IV, preferred monomeric carbon sources.

Characterization of filament forming Bacillus strains isolated from bulking sludge

SummaryFilament-forming bacilli were isolated from bulking sludge. They were physiologically very similar. However, they developed into rhizoid or non-rhizoid colonies. According to their morphological, physiological, and genetical properties the isolates were identified as Bacillus mycoides and Bacillus cereus.

Arogenate (Pretyrosine) Pathway of Tyrosine and Phenylalanine Biosynthesis in Pseudomonas aureofaciens ATCC 15926

Assays of enzyme activities suggest that arogenate, the product of prephenate transamination, is an intermediate in the biosynthesis of both phenylalanine and tyrosine in Pseudomonas aureofaciens ATCC 15926. In addition to prephenate dehydratase and prephenate dehydrogenase, arogenate dehydratase and arogenate dehydrogenase activities were demonstrated. This pattern of aromatic amino acid biosynthesis in pseudomonads had previously been demonstrated only in P. aeruginosa. Arogenate dehydrogenase from P. aureofaciens differs from that in P. aeruginosa in its utilization of either NAD+ or NADP+ as cofactor and its inhibition by L-tyrosine. During ammonium sulphate fractionation, arogenate dehydratase co-precipitated with prephenate dehydratase I activity and not with prephenate dehydratase II. The pattern of regulation of the arogenate route to tyrosine in P. aureofaciens ATCC 15926 differed from that previously reported for strain ATCC 13986.

Regulation of phenylalanine and tyrosine biosynthesis in Pseudomonas aureofaciens ATCC 15926.

Association patterns and regulatory properties of chorismate mutase, prephenate dehydratase and prephenate dehydrogenase from Pseudomonas aureofaciens ATCC 15926 were studied. Prephenate dehydrogenase (molecular weight 95000) was separated by Sephadex G-100 chromatography from both the chorismate mutase-prephenate dehydratase I complex (molecular weight 75000) and from a second, low molecular weight prephenate dehydratase (prephenate dehydratase II; molecular weight 30000). The chorismate mutase-prephenate dehydratase complex persisted after DEAE-Sephadex A-50 chromatography. With the exception of prephenate dehydratase II, enzyme activities were influenced by endproducts. Chorismate mutase was competitively inhibited by L-phenylalanine (Ki=3.5 microM). Prephenate dehydratase I was inhibited by L-phenylalanine (Ki=8 microM) and activated by L-tyrosine (Ka=5 microM). Prephenate dehydrogenase was feedback-inhibited by L-tyrosine. Substrate saturation curves of chorismate mutase and of prephenate dehydratase II were hyperbolic with Km values of 0.31 mM for chorismate and 0.015 mM for prephenate, respectively. The substrate saturation curve of the complexed prephenate dehydratase I was sigmoid; a Km value of 0.18 mM was calculated for prephenate. Chorismate mutase, prephenate dehydratase and prephenate dehydrogenase were not repressed by aromatic amino acids.

Isolierung von 7-Chorindol-3-acetamid aus Pseudomonas aureofaciens ATCC 15926 / Isolation of 7-Chloroindole-3-acetamide from Pseudomonas aureofaciens ATCC 15926

Abstract 7-Chloroindole-3-acetamide and indole-3-acetamide were enzymatically formed from crude extracts of Pseudomonas aureofaciens supplemented with 7-chloro-ʟ-tryptophan or ʟ-tryptophan. The metabolites were identified by UV-, IR-, GC-MS-spectra.