Biotransformation of diphenyl ether by the yeastTrichosporon beigelii SBUG 752

Trichosporon beigelii SBUG 752 was able to transform diphenyl ether. By TLC, HPLC, GC, GC-MS, NMR- and UV-spectroscopy, several oxidation products were identified. The primary attack was initiated by a monooxygenation step, resulting in the formation of 4-hydroxydiphenyl ether, 2-hydroxydiphenyl ether and 3-hydroxydiphenyl ether (48:47:5). Further oxidation led to 3,4-dihydroxydiphenyl ether. As a characteristic product resulting from the cleavage of an aromatic ring, the lactone of 2-hydroxy-4-phenoxymuconic acid was identified. The possible mechanism of ring cleavage to yield this metabolite is discussed.     

Crown alterations induced by decline: a study of relationships between growth rate and crown morphology in beech (Fagus sylvatica L.)

One of the first symptoms expressed by declining trees is reduced growth in stem diameter and length increment. The possibility of a relationship between length increment and crown thinning in beech (Fagus sylvatica L.) was investigated by developing a computer model to simulate first order branching patterns of the apical 2 m of monopodially branching beech trees, 70–100 years old, for a range of length increment rates. The model was based on values for branching angle, main axis and branch length increment, number of branches produced per year and branch mortality rates for six healthy and declining trees. Shoot growth rates in the apical 2 m of the sample trees ranged from about 5 cm/year (decline class 3) to 43 cm/ year (healthy). Simulations of branching patterns in the apical 2 m of trees growing at different rates indicated that, when growth rate exceeded about 20 cm/year, total first order branch length and area explored were independent of growth rate. When growth rates fell below this value there was a reduction in total area explored and first order branch length due primarily to the formation of fewer branches. More acute branching angles contributed to a reduction in the area explored. Growth rate-related crown thinning could increase the risk of bark necrosis and secondary pathogen infection during dry and/or hot spells.     

The xylanase introns from Cryptococcus albidus are accurately spliced in transgenic tobacco plants

The xylanase gene from Cryptococcus albidus contains seven introns. Genomic and cDNA clones under the control of the CaMV 35S promoter were transferred into tobacco plants using Agrobacterium-mediated cell transformation. The genes were transcribed and the mRNAs were amplified by the polymerase chain reaction using primers on each side of the intron region. About 90% of the amplification products from plants transformed with the genomic clone corresponded to the size of the pre-mRNA (1.2 kb) and 10% represented the spliced product (0.85 kb). The 0.85 kb fragment was cloned and sequenced and the result indicated that the introns from the xylanase gene were accurately spliced by the plant cells.     

A substance released by metamorphosing larvae and young polyps ofHydractinia echinata induces metamorphosis in conspecific larvae

Summary A metamorphosis-inducing factor was isolated from medium conditioned by either metamorphosing larvae or 3-day postmetamorphic primary polyps. The factor has a molecular weight 8 kDa and is heatlabile. It does not induce metamorphosis of isolated posterior fragments and is therefore not identical to the internal signal described by Schwoerer-Böhning et al. (1990). The biological significance of the substance is currently unclear, therefore its inducing activity may be a side effect.     

Rhodobacteraceae on the marine brown alga Fucus spiralis are abundant and show physiological adaptation to an epiphytic lifestyle

Macroalgae harbour specific microbial communities on their surface that have functions related to host health and defence. In this study, the bacterial biofilm of the marine brown alga Fucus spiralis was investigated using 16S rRNA gene amplicon-based analysis and isolation of bacteria. Rhodobacteraceae (Alphaproteobacteria) were the predominant family constituting 23% of the epibacterial community. At the genus level, Sulfitobacter, Loktanella, Octadecabacter and a previously undescribed cluster were most abundant, and together they comprised 89% of the Rhodobacteraceae. Supported by a specific PCR approach, 23 different Rhodobacteraceae-affiliated strains were isolated from the surface of F. spiralis, which belonged to 12 established and three new genera. For seven strains, closely related sequences were detected in the 16S rRNA gene dataset. Growth experiments with substrates known to be produced by Fucus spp. showed that all of them were consumed by at least three strains, and vitamin B₁₂ was produced by 70% of the isolates. Since growth of F. spiralis depends on B₁₂ supplementation, bacteria may provide the alga with this vitamin. Most strains produced siderophores, which can enhance algal growth under iron-deficient conditions. Inhibiting properties against other bacteria were only observed when F. spiralis material was present in the medium. Thus, the physiological properties of the isolates indicated adaption to an epiphytic lifestyle.     

Thiolutin inhibits utilization of glucose and other carbon sources in cells of Escherichia coli

Thiolutin was found to inhibit the utilization of glucose and other growth substrates in Escherichia coli. The inhibition was detected by a sharp drop of the respiration rate after addition of the antibiotic. The actual function affected was allocated to the cytoplasmic membrane of the bacterial cells by the following evidence:

Ammonia rhythm in Microcystis firma studied by in vivo 15N and 31P NMR spectroscopy

Cultures of the cyanobacterium Microcystis firma show rhythmic uptake and release of ammonia under conditions of carbon limitation. The massive removal of ammonia from the medium during the first light phase has little impact on the intracellular pH: a pH shift of less than 0.2 U towards the alkaline can be measured by in vivo ³¹P NMR. Furthermore, the energy status of the cells remains regulated. In vivo ¹⁵N NMR of M. firma, cultivated either with labelled nitrate or ammonia as the sole nitrogen source, reveals only gradual differences in the pool of free amino acids. Additionally both cultivation types show -aminobutyric acid, acid amides and yet unassigned secondary metabolites as nitrogen storing compounds. Investigating the incorporation of nitrogen under carbon limitation, however, only the amide nitrogen of glutamine is found permanently labelled in situ. While transamination reactions are blocked, nitrate reduction to ammonia can still proceed. Cation exchange processes in the cell wall are considered regarding the ammonia disappearance in the first phase, and the control of ammonia uptake is discussed with respect to the avoidance of intracellular toxification.Abbreviations GABA -aminobutyric acid - GOGAT glutamate synthase - GS glutamine synthetase - MDP methylene diphosphonate - MOPSO 3-(N-morpholino)-2-hydroxy-propanesulfonic acid - NDPS nucieoside diphosphosugars - NOE nuclear Overhauser effect - NMR nuclear magnetic resonance For convenience, the term ammonia is used throughout to denote ammonia or ammonium ion when there is no good evidence as to which chemical species is involved     

A kinetic study on iron stimulation of the xanthine oxidase dependent oxidation of ascorbate

Xanthine oxidase reduces molecular oxygen to H₂O₂ and superoxide radicals during its catalytic action on xanthine, hypoxanthine or acetaldehyde. Ascorbate is catalytically oxidized by the superoxide radicals generated, when present in the reaction solution (Nishikimi 1975). The present study shows that iron ions markedly stimulate the enzyme dependent ascorbate oxidation, by acting as a red/ox-cycling intermediate between the oxidase and ascorbate. An apparent K_m-value of 10.8 M characterized the iron stimulatory effect on the reaction at pH 6.0. Reduced transition-state metals can be oxidized by H₂O₂ through a Fenton-type reaction. Catalase was found to reduce the effect of iron on the enzyme dependent ascorbate oxidation, strongly suggesting that H₂O₂, produced during catalysis, is involved in the oxidation of ferrous ions.     

The Sub-Cellular Localization of WRAP53 Has Prognostic Impact in Breast Cancer

WRAP53 protein controls intracellular trafficking of DNA repair proteins, the telomerase enzyme, and splicing factors. Functional loss of the protein has been linked to carcinogenesis, premature aging and neurodegeneration. The aim of this study was to investigate the prognostic significance of WRAP53 protein expression in breast cancer. A tissue microarray was constructed from primary breast tumors and immunostained by a polyclonal WRAP53 antibody to assess the protein expression pattern. Two different patient cohorts with long term follow-up were studied; a test- and a validation set of 154 and 668 breast tumor samples respectively. Breast cancer patients with tumor cells lacking the expression of WRAP53 in the nucleus had a significantly poorer outcome compared to patients with tumor cells expressing this protein in the nuclei (HR = 1.95, 95%CI = 1.09–3.51, p = 0.025). Nuclear localization of WRAP53 was further shown to be an independent marker of prognosis in multivariate analysis (HR = 2.57, 95%CI = 1.27–5.19, p = 0.008), and also significantly associated with better outcome in patients with TP53 mutation. Here we show that the sub-cellular localization of the WRAP53 protein has a significant impact on breast cancer survival, and thus has a potential as a clinical marker in diagnostics and treatment.