Differential accumulation of transcripts encoding sulfur assimilation enzymes upon sulfur and/or nitrogen deprivation in Arabidopsis thaliana.
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Expression of nine genes encoding enzymes involved in the sulfur assimilation pathway was examined by RNA blot hybridization. Significantly increased levels of transcripts encoding ATP sulfurylase and APS reductase were apparent under sulfur deprivation. However, in the absence of nitrogen, their responsiveness to sulfur deprivation was markedly reduced. Results suggest that the sulfur assimilation pathway is regulated at the transcriptional level by both nitrogen and sulfur sources. (+info)
Studies on the anxiolytic activity of Eurycoma longifolia Jack roots in mice.
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The anxiolytic effect of Eurycoma longifolia Jack in mice was examined. Fractions of E. longifolia Jack extract produced a significant increase in the number of squares crossed (controls= 118.2 +/- 10.2 squares), but significantly decreased both the immobility (controls = 39.4+/- 4.0 sec) and fecal pellets (controls= 12.3 +/-2.1 fecal pellets) when compared with control mice in the open-field test; they significantly increased the number of entries (controls=6.7+/-0.5 entries) and time spent (controls=42.9+/-0.1 sec) in the open arms, but decreased both the number of entries (controls= 13.2+/-0.7 entries) and time spent (controls= 193.4+/-0.7 sec) when compared with the control mice in the closed arms of the elevated plus-maze test. Furthermore, fractions of E. longifolia Jack extract decreased the fighting episodes significantly (controls= 18.0+/-0.4 fighting episodes) when compared with control mice. In addition, these results were found to be consistent with anxiolytic effect produced by diazepam. Hence, this study supports the medicinal use of this plant for anxiety therapy. (+info)
A gene encoding the cytokinin enzyme zeatin O-xylosyltransferase of Phaseolus vulgaris.
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Zeatin is the most active and ubiquitous form of the naturally occurring cytokinins. Glycosyl conjugates of zeatin are found in many plant tissues and are considered important for storage and protection against degradative enzymes. Two enzymes catalyzing the formation of O-glycosyl derivatives of zeatin have been characterized, O-glucosyltransferase and O-xylosyltransferase, occurring in seeds of lima bean (Phaseolus lunatus) and bean (Phaseolus vulgaris), respectively. Recently, the ZOG1 gene (zeatin O-glucosyltansferase) was isolated from P. lunatis (). Based on the ZOG1 sequence, the ZOX1 gene (zeatin O-xylosyltransferase) was cloned from P. vulgaris. ZOX1 contains an open reading frame of 1362 bp that codes for a 454-amino acid peptide of 51 kD. The recombinant protein has properties identical to the native enzyme: it catalyzes O-xylosylzeatin formation with UDP-Xyl as a glycosyl donor but does not recognize UDP-Glucose as a substrate. The ZOX1 and ZOG1 genes exhibit 93% identity at the nucleotide level and 90% similarity at the amino acid level. Neither gene contains introns. These zeatin-specific genes and their promoters will be useful for studies of the regulation of active versus storage forms of cytokinins. Comparison of sequences encoding similar enzymes with distinct substrate specificity may lead to identification of epitopes specific to cytokinin and glycosyl donor molecules. (+info)
Protective effects of Ginkgo biloba extract against lysophosphatidylcholine-induced vascular endothelial cell damage.
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AIM: To study the protective effects of Ginkgo biloba extract (GbE) against endothelial cell damage induced by lysophosphatidylcholine (LPC). METHODS: The vasorelaxation response to acetylcholine (ACh) were investigated in the isolated rabbit thoracic aorta. Lipid peroxidation products were determined by measuring thiobarbituric acid reactive substance. RESULTS: GbE attenuated the inhibition of vasorelaxation response to ACh and prevented the LPC-induced increase of malondialdehyde (MDA) content both in thoracic aortae. GbE prevented the leakage of LDH and the increase of MDA content in cultured endothelial cells in a concentration-dependent manner. GbE also markedly increased epoprostenol level in cultured endothelial cells treated with LPC. CONCLUSION: GbE protected endothelial cells against LPC-induced damage due to reduction in lipid peroxidation and facilitation of synthesis and/or release of epoprostenol. (+info)
Hemorheology and walking of peripheral arterial occlusive diseases patients during treatment with Ginkgo biloba extract.
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AIM: To study the effects of Ginkgo biloba extract 761 (GbE) from the points of view of hemorheology for patients of peripheral arterial occlusive diseases (PAOD). METHODS: The treatment with GbE (240 mg.d-1, po) and the pain-free walking distance (PFWD) were carried out for 24 PAOD patients (12 nondiabetic, ND and 12 diabetic, D) over 48 wk. The parameters erythrocyte stiffness (ES) and relaxation time (RT), the blood plasma viscosity (eta), the plasma fibrinogen concentration (Cf) and the blood sedimentation rate (BSR), the PFWD, and maximal walking distance (MWD) were determined at 6 wk before treatment (-6), at the beginning of the treatment (0), and after 6, 11, 16, and 48 wk of treatment. RESULTS: At wk -6, ES and RT of both the ND- and D-group were not significantly different from a healthy control group. At wk 0, stiffness and RT were significantly higher than healthy control, and the mean PFWD was only 111 m. The eta value was significantly elevated and Cf and BSR were enhanced. Throughout 11 wk of treatment ES, RT, eta, and Cf decreased gradually and PFWD improved. Between 16 and 48 wk, ES, and RT were no longer significantly different from the controls, whereas eta and Cf decreased gradually but remained higher than normal, BSR decreased, and the PFWD improved by a factor of 3.8 times (D) and 3.3 times (ND). CONCLUSION: GbE gives therapeutic effects in PAOD patients. (+info)
Structural and putative regulatory genes involved in cellulose synthesis in Rhizobium leguminosarum bv. trifolii.
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Six genes involved in cellulose synthesis in Rhizobium leguminosarum bv. trifolii were identified using Tn5 mutagenesis. Four of them displayed homology to the previously cloned and sequenced Agrobacterium tumefaciens cellulose genes celA, celB, celC and celE. These genes are organized similarly in R. leguminosarum bv. trifolii. In addition, there were strong indications that two tandemly located genes, celR1 and celR2, probably organized as one operon, are involved in the regulation of cellulose synthesis. The deduced amino acid sequences of these genes displayed a high degree of similarity to the Caulobacter crescentus DivK and PleD proteins that belong to the family of two-component response regulators. This is to our knowledge the first report of genes involved in the regulation of cellulose synthesis. Results from attachment assays and electron microscopic studies indicated that cellulose synthesis in R. leguminosarum bv. trifolii is induced upon close contact with plant roots during the attachment process. (+info)
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)
Interactions of 6-gingerol and ellagic acid with the cardiac sarcoplasmic reticulum Ca2+-ATPase.
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The inotropic/lusitropic effects of beta-adrenergic agonists on the heart are mediated largely by protein kinase A (PKA)-catalyzed phosphorylation of phospholamban, the natural protein regulator of the Ca2+ pump present in sarcoplasmic reticulum (SR) membranes. Gingerol, a plant derivative, is known to produce similar effects when tested in isolated cardiac muscle. The purpose of the present study was to compare the effects of gingerol and another plant derivative, ellagic acid, on the kinetics of the SR Ca2+ pump with those of PKA-catalyzed phospholamban phosphorylation to elucidate their mechanisms of Ca2+ pump regulation. As previously demonstrated for PKA, 50 microM gingerol or ellagic acid increased Vmax(Ca) of Ca2+ uptake and Ca2+-ATPase activity assayed at millimolar ATP concentrations in light cardiac SR vesicles. Unlike PKA, which decreases Km(Ca), neither compound had a significant effect on Km(Ca) in unphosphorylated vesicles. However, gingerol increased Km(Ca) in phosphorylated vesicles, in which Ca2+ uptake was significantly increased further at saturating Ca2+ and remained unchanged at subsaturating Ca2+. An inhibition of Ca2+ uptake by gingerol at micromolar MgATP concentrations was overcome with increasing MgATP concentrations. The stimulation of Ca2+ uptake attributable to gingerol in unphosphorylated microsomes at saturating Ca2+ was 30% to 40% when assayed at 0.05 to 2 mM MgATP and only about 12% in phosphorylated microsomes as well as in rabbit fast skeletal muscle light SR. The present results support the view that an ATP-dependent increase in Vmax(Ca) of the SR Ca2+ pump plays an important role in mediating cardiac contractile responses to gingerol and phospholamban-dependent beta-adrenergic stimulation. (+info)