Management of nursery practices for efficient ectomycorrhizal fungi application in the production of Quercus ilex

The application of ectomycorrhizal (ECM) fungi on forest nursery production is regarded as part of good management practice. However, before employing large scale inoculations in a nursery the interaction between ECM symbionts, growth substrate and fertilisation input should be studied to select the most suitable nursery practices for promoting plant growth and ECM colonisation. In this study, seedlings of Quercus ilex were inoculated with Paxillus involutus, Hebeloma mesophaeum or Cenococcum geophilum and grown in three different substrates commonly used in forest nurseries: peat-based compost, forest soil or composted pine bark. The effect of various fertilisation regimes was also studied. The choice of substrate had a significant effect on plant growth and ECM colonisation. The most appropriate combination of substrate and ECM fungus for Q. ilex growth and nutrition was peat and H. mesophaeum. Plants grown on a peat-based compost and inoculated with H. mesophaeum had a significantly greater biomass and leaf phosphorus concentration without fertilisation. Composted pine bark was found not to be suitable for growth or for mycorrhization. If the appropriate growth substrate is selected, it is possible to replace the use of chemical fertilisers by inoculation with selected ECM fungi. This results in a significant increase in plant development, and thus ECM fungi can be recommended as a more environmental friendly biotechnological approach to plant management in the nursery.     

Interaction of C60 fullerene with lipids

Unsaturated lipids when exposed to air at room temperature undergo a slow autoxidation. When fullerene C₆₀ was dissolved in selected lipids (ethyl oleate, ethyl linoleate, linseed oil and castor oil) the spectrophotometric analysis shows that the oxidation is concentrated to C₆₀ which is converted to an epoxide C₆₀O. Thus, fullerene C₆₀ displays antioxidant activity not only when dissolved in unsaturated lipids but also, more generally, when dissolved in unsaturated solvents subjected to autoxidation like, for example, in cyclohexene. The behaviour of C₆₀ in ethyl oleate has been compared with that of the known antioxidant TMPPD (N,N′,N,N,′-tetramethyl-p-phenylenediamine) in ethyl oleate. The mechanism of the antioxidant action of C₆₀ in lipids has been proposed. The kinetics of C₆₀ oxidation in lipids was determined spectrophotometrically both at room temperature in the dark and under UV irradiation. The oxidized products derived from C₆₀ photo-oxidation in lipids have been identified.     

A decade of land use contributes to changes in the chemistry,biochemistry and bacterial community structures of soils in the Cerrado

The bacterial community structures (BCSs) of Cerrado soils cultivated under conventional tillage (CT), no-tillage (NT) and under native Cerrado (NC) vegetation were evaluated using PCR/DGGE of bacterial 16S rRNA (rrs) and rpoB genes and of Pseudomonas group genes. Soil chemical analysis, microbial biomass and the enzyme activities were also evaluated and correlated with the BCS measurements. The multivariate ordinations of DGGE profiles showed differences between the BCS of the NC area and those from cultivated areas. The BCSs of the CT and NT areas also differed in all DGGE fingerprints, including changes in the profile of Pseudomonas populations, indicating that agricultural systems can also be responsible for changes within specific microbial niches, although the clearest differences were found in the rpoB profiles. The MRPP analysis demonstrated significant differences between the BCSs from different soil layers of NT areas based on all gene fingerprints and those of NC areas based on bacterial 16S rRNA and rpoB genes fingerprints. No differences were observed in the microbial fingerprints of CT samples from different depths, indicating that ploughing affected the original BCS stratification. The BCS from NC areas, based on all gene fingerprints, could be related to higher levels of soil acidity and higher amounts of MBC and of phosphatase activity. In contrast, the BCSs from cultivated areas were related to higher levels of Ca + Mg, P and K, likely as a result of a history of chemical fertilisation in these areas. The relationships between rpoB and Pseudomonas BCSs and all chemical and biochemical properties of soils were significant, according to a Mantel test (P < 0.05), indicating that the different changes in soil properties induced by soil use or management may drive the formation of the soil BCS.     

A Novel Mechanism for SUMO System Control: Regulated Ulp1 Nucleolar Sequestration

The small ubiquitin-related modifiers (SUMOs) are evolutionarily conserved polypeptides that are covalently conjugated to protein targets to modulate their subcellular localization, half-life, or activity. Steady-state SUMO conjugation levels increase in response to many different types of environmental stresses, but how the SUMO system is regulated in response to these insults is not well understood. Here, we characterize a novel mode of SUMO system control: in response to elevated alcohol levels, the Saccharomyces cerevisiae SUMO protease Ulp1 is disengaged from its usual location at the nuclear pore complex (NPC) and sequestered in the nucleolus. We further show that the Ulp1 region previously demonstrated to interact with the karyopherins Kap95 and Kap60 (amino acids 150 to 340) is necessary and sufficient for nucleolar targeting and that enforced sequestration of Ulp1 in the nucleolus significantly increases steady-state SUMO conjugate levels, even in the absence of alcohol. We have thus characterized a novel mechanism of SUMO system control in which the balance between SUMO-conjugating and -deconjugating activities at the NPC is altered in response to stress via relocalization of a SUMO-deconjugating enzyme.The small ubiquitin-related modifiers (SUMOs) are a family of evolutionarily conserved polypeptides that are conjugated to protein targets via the concerted action of SUMO-specific E1 (activation), E2 (conjugation), and E3 (ligase) enzymes to effect changes in subcellular localization, half-life, or target activity. A family of SUMO-specific proteases act to remove the modifier from conjugates (8, 20). The SUMO system has been implicated in a variety of critical cellular functions, such as DNA repair and replication, RNA metabolism, and stress responses (8, 16, 20). Importantly, the SUMO system is highly dynamic and the SUMO pathway enzymes appear to work together to precisely control SUMO conjugate levels in the cell (8, 16, 20). However, how the SUMO system itself is regulated is poorly understood.Localization of the SUMO pathway enzymes may play an important role in SUMO system function (21). For example, the budding yeast SUMO protease Ulp1 is tethered to the nuclear face of the nuclear pore complex (NPC) via an unconventional interaction with the karyopherin Kap121 and the heterodimeric Kap95/Kap60 complex (12, 13, 23). However, this SUMO protease is not maintained exclusively at the NPC but appears to be mobile, effecting desumoylation at diverse subcellular locations: e.g., during mitosis, Saccharomyces cerevisiae Ulp1 is recruited to the septin ring to desumoylate septins (15), Schizosaccharomyces pombe Ulp1 localization is regulated throughout the cell cycle (31), and a mammalian Ulp1 homolog, SENP2, is shuttled between the nucleus and the cytoplasm (7). Consistent with these observations, SUMO conjugate levels are significantly altered in yeast strains expressing mislocalized Ulp1 (13, 37).Dramatic changes in SUMO conjugate populations have been noted in response to many different types of stresses in yeasts, mammals, and plants (9, 17, 27, 32, 38). For example, in S. cerevisiae, significantly increased steady-state SUMO conjugate levels are observed in response to elevated concentrations of ethanol (38). To better understand how the SUMO system is regulated in response to stress, we utilized alcohol as a model of a physiologically relevant stressor in yeast. Here, we demonstrate that alcohol stress results in a rapid, reversible nucleolar sequestration of Ulp1 and that enforced localization of Ulp1 in the nucleolus leads to a dramatic increase in steady-state SUMO conjugate levels. This is the first demonstration of regulated modulation of the intracellular localization of a SUMO enzyme in response to stress and thus represents a novel mechanism for SUMO system control.     

Synthesis and pharmacological evaluation of novel 1,3,8- and 1,3,7,8-substituted xanthines as adenosine receptor antagonists

A number of novel xanthines bearing a variety of substituents at positions 1, 3, 7 and 8 were prepared and evaluated for their binding affinity to the human adenosine receptor A₁, A_2A, A_2B and A₃ subtypes. Several of the 1,3,8- and 1,3,7,8-substituted xanthines showed moderate-to-high affinity at human A_2B and A₁ receptors, with the most active compound (14q) having a pK_i of 7.57 nM for hA_2B receptors and a selectivity over hA_2A receptors of 8.1-fold and hA₁ receptors of 3.7-fold.     

A new series of flavones,thioflavones, and flavanones as selective monoamine oxidase-B inhibitors

A new series of synthetic flavones, thioflavones, and flavanones has been synthesized and evaluated as potential inhibitors of monoamine oxidase isoforms (MAO-A and -B). The most active series is the flavanone one with higher selective inhibitory activity against MAO-B. Some of these flavanones (mainly the most effective) have been separated and tested as single enantiomers. In order to investigate the MAOs recognition of the most active and selective compounds, a molecular modeling study has been performed using available Protein Data Bank (PDB) structures as receptor models for docking experiments.     

A novel T7 RNA polymerase dependent expression system for high-level protein production in the phototrophic bacterium Rhodobacter capsulatus

The functional expression of heterologous genes using standard bacterial expression hosts such as Escherichia coli is often limited, e.g. by incorrect folding, assembly or targeting of recombinant proteins. Consequently, alternative bacterial expression systems have to be developed to provide novel strategies for protein synthesis exceeding the repertoire of the standard expression host E. coli.Here, we report on the construction of a novel expression system that combines the high processivity of T7 RNA polymerase with the unique physiological properties of the facultative photosynthetic bacterium Rhodobacter capsulatus. This system basically consists of a recombinant R. capsulatus T7 expression strain (R. capsulatus B10S-T7) harboring the respective polymerase gene under control of a fructose inducible promoter. In addition, a set of different broad-host-range vectors (pRho) was constructed allowing T7 RNA polymerase dependent and independent target gene expression in R. capsulatus and other Gram-negative bacteria. The expression efficiency of the novel system was studied in R. capsulatus and E. coli using the yellow fluorescent protein (YFP) as model protein. Expression levels were comparable in both expression hosts and yielded up to 80 mg/l YFP in phototrophically grown R. capsulatus cultures. This result clearly indicates that the novel R. capsulatus-based expression system is well suited for the high-level expression of soluble proteins.