Multi-enzymatic glucosylation using Eucalyptus UDP-glucosyltransferase coupled UDPglucose-fermentation by bakers' yeast.
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The enzymatic synthesis of glucoside compounds using a membrane-associated UDP-glucosyltransferase fraction from Eucalyptus perriniana cultured cells as a water-insoluble catalyst (N. Nakajima, et. al., J. Ferment. Bioeng., 84 (5), pp. 455-460, 1997) has been effectively done by coupling UDPglucose-fermentation by bakers' yeast. For example, beta-thujaplicin (hinokitiol) and p-aminobenzoic acid were converted respectively to their corresponding beta-D-monoglucosides with the conversion rate of around 24-26% by the multi-enzymatic system with UDPglucose as a glucose donor, which is produced by yeast cells from glucose and 5'-UMP. Addition of either cellobiose, a substrate of beta-glucosidase, or DL-1,2-anhydro-myo-inositol, an inhibitor for the enzyme in the reaction mixture, could increased the yield of these beta-D-monoglucosides. This new enzymatic system could also be used for the synthesis of flavonoid glucosides such as isoquercitrin (quercetin 3-O-beta-D-glucoside). (+info)
A novel class of ectomycorrhiza-regulated cell wall polypeptides in Pisolithus tinctorius.
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Development of the ectomycorrhizal symbiosis leads to the aggregation of fungal hyphae to form the mantle. To identify cell surface proteins involved in this developmental step, changes in the biosynthesis of fungal cell wall proteins were examined in Eucalyptus globulus-Pisolithus tinctorius ectomycorrhizas by two-dimensional polyacrylamide gel electrophoresis. Enhanced synthesis of several immunologically related fungal 31- and 32-kDa polypeptides, so-called symbiosis-regulated acidic polypeptides (SRAPs), was observed. Peptide sequences of SRAP32d were obtained after trypsin digestion. These peptides were found in the predicted sequence of six closely related fungal cDNAs coding for ectomycorrhiza up-regulated transcripts. The PtSRAP32 cDNAs represented about 10% of the differentially expressed cDNAs in ectomycorrhiza and are predicted to encode alanine-rich proteins of 28.2 kDa. There are no sequence homologies between SRAPs and previously identified proteins, but they contain the Arg-Gly-Asp (RGD) motif found in cell-adhesion proteins. SRAPs were observed on the hyphal surface by immunoelectron microscopy. They were also found in the host cell wall when P. tinctorius attached to the root surface. RNA blot analysis showed that the steady-state level of PtSRAP32 transcripts exhibited a drastic up-regulation when fungal hyphae form the mantle. These results suggest that SRAPs may form part of a cell-cell adhesion system needed for aggregation of hyphae in ectomycorrhizas. (+info)
Hypaphorine from the ectomycorrhizal fungus Pisolithus tinctorius counteracts activities of indole-3-acetic acid and ethylene but not synthetic auxins in eucalypt seedlings.
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Very little is known about the molecules regulating the interaction between plants and ectomycorrhizal fungi during root colonization. The role of fungal auxin in ectomycorrhiza has repeatedly been suggested and questioned, suggesting that, if fungal auxin controls some steps of colonized root development, its activity might be tightly controlled in time and in space by plant and/or fungal regulatory mechanisms. We demonstrate that fungal hypaphorine, the betaine of tryptophan, counteracts the activity of indole-3-acetic acid (IAA) on eucalypt tap root elongation but does not affect the activity of the IAA analogs 2,4-D ((2,4-dichlorophenoxy)acetic acid) or NAA (1-naphthaleneacetic acid). These data suggest that IAA and hypaphorine interact during the very early steps of the IAA perception or signal transduction pathway. Furthermore, while seedling treatment with 1-amincocyclopropane-1-carboxylic acid (ACC), the precursor of ethylene, results in formation of a hypocotyl apical hook, hypaphorine application as well as root colonization by Pisolithus tinctorius, a hypaphorine-accumulating ectomycorrhizal fungus, stimulated hook opening. Hypaphorine counteraction with ACC is likely a consequence of hypaphorine interaction with IAA. In most plant-microbe interactions studied, the interactions result in increased auxin synthesis or auxin accumulation in plant tissues. The P. tinctorius / eucalypt interaction is intriguing because in this interaction the microbe down-regulates the auxin activity in the host plant. Hypaphorine might be the first specific IAA antagonist identified. (+info)
Leaf respiration of snow gum in the light and dark. Interactions between temperature and irradiance.
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We investigated the effect of temperature and irradiance on leaf respiration (R, non-photorespiratory mitochondrial CO(2) release) of snow gum (Eucalyptus pauciflora Sieb. ex Spreng). Seedlings were hydroponically grown under constant 20 degrees C, controlled-environment conditions. Measurements of R (using the Laisk method) and photosynthesis (at 37 Pa CO(2)) were made at several irradiances (0-2,000 micromol photons m(-2) s(-1)) and temperatures (6 degrees C-30 degrees C). At 15 degrees C to 30 degrees C, substantial inhibition of R occurred at 12 micromol photons m(-2) s(-1), with maximum inhibition occurring at 100 to 200 micromol photons m(-2) s(-1). Higher irradiance had little additional effect on R at these moderate temperatures. The irradiance necessary to maximally inhibit R at 6 degrees C to 10 degrees C was lower than that at 15 degrees C to 30 degrees C. Moreover, although R was inhibited by low irradiance at 6 degrees C to 10 degrees C, it recovered with progressive increases in irradiance. The temperature sensitivity of R was greater in darkness than under bright light. At 30 degrees C and high irradiance, light-inhibited rates of R represented 2% of gross CO(2) uptake (v(c)), whereas photorespiratory CO(2) release was approximately 20% of v(c). If light had not inhibited leaf respiration at 30 degrees C and high irradiance, R would have represented 11% of v(c). Variations in light inhibition of R can therefore have a substantial impact on the proportion of photosynthesis that is respired. We conclude that the rate of R in the light is highly variable, being dependent on irradiance and temperature. (+info)
Emission of isoprene from salt-stressed Eucalyptus globulus leaves.
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Eucalyptus spp. are among the highest isoprene emitting plants. In the Mediterranean area these plants are often cultivated along the seashore and cope with recurrent salt stress. Transient salinity may severely but reversibly reduce photosynthesis and stomatal conductance of Eucalyptus globulus leaves but the effect on isoprene emission is not significant. When the stress is relieved, a burst of isoprene emission occurs, simultaneously with the recovery of photosynthetic performance. Later on, photosynthesis, stomatal conductance, and isoprene emission decay, probably because of the onset of leaf senescence. Isoprene emission is not remarkably affected by the stress at different light intensities, CO(2) concentrations, and leaf temperatures. When CO(2) was removed and O(2) was lowered to inhibit both photosynthesis and photorespiration, we found that the residual emission is actually higher in salt-stressed leaves than in controls. This stimulation is particularly evident at high-light intensities and high temperatures. The maximum emission occurs at 40 degrees C in both salt-stressed and control leaves sampled in ambient air and in control leaves sampled in CO(2)-free and low-O(2) air. However, the maximum emission occurs at 45 degrees C in salt-stressed leaves sampled in CO(2)-free and low-O(2) air. Our results suggest the activation of alternative non-photosynthetic pathways of isoprene synthesis in salt-stressed leaves and perhaps in general in leaves exposed to stress conditions. The temperature dependence indicates that this alternative synthesis is also under enzymatic control. If this alternative synthesis still occurs in the chloroplasts, it may involve a thylakoid-bound isoprene synthase. (+info)
Mass, temperature and metabolic effects on discontinuous gas exchange cycles in eucalyptus-boring beetles (Coleoptera: cerambycidae).
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Ventilatory accommodation of changing metabolic rates is a relatively little-studied aspect of the discontinuous gas exchange cycles (DGCs) that occur in a wide variety of terrestrial arthropods. We used correlation analysis of resting metabolic rate (RMR, measured as the rate of CO(2) emission; V(CO2)) and several components of the DGC to examine accommodation to both temperature-induced changes and individual variation in RMR in two wood-boring beetles (Phorocantha recurva and P. semipunctata; Coleoptera: Cerambycidae). At low to moderate ambient temperatures (T(a); 10-20 degrees C), Phorocantha spp. displayed a characteristic DGC with relatively brief but pronounced open (O) phase bursts of CO(2) emission separated by longer periods of low V(CO2), the flutter (F) phase. However, the V(CO2) never fell to zero, and we could not reliably differentiate a typical closed (C) phase from the F phase. Accordingly, we pooled the C and F phases for analysis as the C+F phase. At higher T(a) (30 degrees C), the duration of the combined C+F phase was greatly reduced. There were no differences between the two species or between males and females in either RMR or characteristics of the DGC. We found large variation in the major DGC components (cycle frequency, durations and emission volumes of the O and C+F phases); much of this variation was significantly repeatable. Accommodation of temperature-induced RMR changes was almost entirely due to changes in frequency (primarily in the C+F phase), as has been found in several other discontinuously ventilating arthropods. Frequency changes also contributed to accommodation at constant T(a), but modulation of emission volumes (during both O and C+F phases) played a larger role in this case. The DGC is often viewed as a water conservation mechanism, on the basis that respiratory evaporation is minimal during the C and F phases. This hypothesis assumes that the F phase is primarily convective (because of a reduction in tracheal P(O2) and total intratracheal pressure during the C phase). To test this, we measured the DGC in beetles subjected to varying degrees of hypoxia in addition to normoxia. As predicted for a largely diffusive F phase, we found an increase in the volume of CO(2) emitted during the C+F phase in hypoxic conditions (10.4 % oxygen). This finding, together with a reduced tendency to utilize a DGC at high T(a) (when water stress is greatest) and a natural history in which water availability is probably not limiting for any life stage, suggests that a reduction of respiratory evaporation may not have been critical in the evolution of the DGC of Phorocantha spp. Instead, selection may have favored discontinuous ventilation because it facilitates gas exchange in the hypercapnic and hypoxic environments commonly encountered by animals (such as Phorocantha spp.) that live in confined spaces. (+info)
The influence of essential oils on human attention. I: alertness.
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Scientific research on the effects of essential oils on human behavior lags behind the promises made by popular aromatherapy. Nearly all aspects of human behavior are closely linked to processes of attention, the basic level being that of alertness, which ranges from sleep to wakefulness. In our study we measured the influence of essential oils and components of essential oils [peppermint, jasmine, ylang-ylang, 1,8-cineole (in two different dosages) and menthol] on this core attentional function, which can be experimentally defined as speed of information processing. Substances were administered by inhalation; levels of alertness were assessed by measuring motor and reaction times in a reaction time paradigm. The performances of the six experimental groups receiving substances (n = 20 in four groups, n = 30 in two groups) were compared with those of corresponding control groups receiving water. Between-group analysis, i.e. comparisons between experimental groups and their respective control groups, mainly did not reach statistical significance. However, within-group analysis showed complex correlations between subjective evaluations of substances and objective performance, indicating that effects of essentials oils or their components on basic forms of attentional behavior are mainly psychological. (+info)
Percutaneous treatment of chronic MRSA osteomyelitis with a novel plant-derived antiseptic.
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BACKGROUND: Antibiotic-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococcus (VRE, are an increasing problem world-wide, causing intractable wound infections. Complex phytochemical extracts such as tea tree oil and eucalypt-derived formulations have been shown to have strong bactericidal activity against MRSA in vitro. Polytoxinol (PT) antimicrobial, is the trade name of a range of antimicrobial preparations in solution, ointment and cream form. METHODS: We report the first use of this drug, administered percutaneously, via calcium sulphate pellets (Osteoset,TM), into bone, to treat an intractable MRSA infection of the lower tibia in an adult male. RESULTS AND DISCUSSION: Over a three month period his symptoms resolved with a healing response on x-ray and with a reduced CRP. (+info)