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At least 649 records · Page 36Linked to original sources
PubMed2003

Role of a single aquaporin isoform in root water uptake.

Aquaporins are ubiquitous channel proteins that facilitate the transport of water across cell membranes. Aquaporins show a typically high isoform multiplicity in plants, with 35 homologs in Arabidopsis. The integrated function of plant aquaporins and the function of each individual isoform remain poorly understood. Matrix-assisted laser desorption/ionization time-of-flight analyses suggested that Plasma Membrane Intrinsic Protein2;2 (PIP2;2) is one of the abundantly expressed aquaporin isoforms in Arabidopsis root plasma membranes. Two independent Arabidopsis knockout mutants of PIP2;2 were isolated using a PCR-based strategy from a library of plant lines mutagenized by the insertion of Agrobacterium tumefaciens T-DNA. Expression in transgenic Arabidopsis of a PIP2;2 promoter-beta-glucuronidase gene fusion indicated that PIP2;2 is expressed predominantly in roots, with a strong expression in the cortex, endodermis, and stele. The hydraulic conductivity of root cortex cells, as measured with a cell pressure probe, was reduced by 25 to 30% in the two allelic PIP2;2 mutants compared with the wild type. In addition, free exudation measurements revealed a 14% decrease, with respect to wild-type values, in the osmotic hydraulic conductivity of roots excised from the two PIP2;2 mutants. Together, our data provide evidence for the contribution of a single aquaporin gene to root water uptake and identify PIP2;2 as an aquaporin specialized in osmotic fluid transport. PIP2;2 has a close homolog, PIP2;3, showing 96.8% amino acid identity. The phenotype of PIP2;2 mutants demonstrates that, despite their high homology and isoform multiplicity, plant aquaporins have evolved with nonredundant functions.

Amino Acid Sequence↗
PubMed2002

[Studies on the anti-inflammation effect of the TCM prescription of a combination of monkshood root with peony root].

OBJECTIVE: To make a comparison between the single and combined use of Monkshood Root and Peony Root to observe the anti-inflammation effect in the experimental animals. METHOD: The experimental inflammatory models were adopted, i.e. adjuvant-induced polyarthritis carrageenan-induced or formaldehyde-induced rat paw edema, and cotton pellet-induced granuloma formation in rats xylene-induced mouse ear edema, exudation of abdominal blood capillaries of mice, etc. RESULT: The anti-inflammafion effect of Monkshood Root was weaker than that of Peony Root or Peony Root combined with Monkshood Root. It was found that anti-inflammation effect with the drug-cooperation was enhanced more significantly in the formaldehyde-induced or adjuvant-induceed arthritis models than in the carrageenan-induced rat paw edema and other inflammatory models either in the large dosage of 1:1 proportion or in the small dosage of 1:2 proportion. CONCLUSION: The drug-cooperation has a good selective and synergic effect on anti-inflammation.

Aconitum↗
PubMed2005

Nutrient availability and management in the rhizosphere: exploiting genotypic differences.

Crop nutrition is frequently inadequate as a result of the expansion of cropping into marginal lands, elevated crop yields placing increasing demands on soil nutrient reserves, and environmental and economic concerns about applying fertilizers. Plants exposed to nutrient deficiency activate a range of mechanisms that result in increased nutrient availability in the rhizosphere compared with the bulk soil. Plants may change their root morphology, increase the affinity of nutrient transporters in the plasma membrane and exude organic compounds (carboxylates, phenolics, carbohydrates, enzymes, etc.) and protons. Chemical changes in the rhizosphere result in altered abundance and composition of microbial communities. Nutrient-efficient genotypes are adapted to environments with low nutrient availability. Nutrient efficiency can be enhanced by targeted breeding through pyramiding efficiency mechanisms in a desirable genotype as well as by gene transfer and manipulation. Rhizosphere microorganisms influence nutrient availability; adding beneficial microorganisms may result in enhanced availability of nutrients to crops. Understanding the role of plant-microbe-soil interactions in governing nutrient availability in the rhizosphere will enhance the economic and environmental sustainability of crop production.

Breeding↗
PubMed2001

Levels of ACC and related compounds in exudate and extracts of canola seeds treated with ACC deaminase-containing plant growth-promoting bacteria.

It was previously proposed that plant growth-promoting bacteria that possess 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase could utilize ACC that is present in the exudate of germinating canola seeds. The uptake and cleavage of ACC by these bacteria would lower the level of ACC, and thus ethylene within the plant, and reduce the extent of its inhibition on root elongation. To test part of the above mentioned model, ACC levels were monitored in canola seed tissues and exudate during germination. Lower amounts of ACC were present in the exudate and tissues of seeds treated with the plant growth-promoting bacterium Enterobacter cloacae CAL3, than in control seeds treated with MgSO4. The ACC-related compounds, alpha- and gamma-aminobutyric acids, both known to stimulate ethylene production, were also measured in the canola seed exudate and tissues. Approximately the same levels of alpha-aminobutyric acid were present in the exudates of the bacterium-treated seeds and the control seeds, but the amount of alpha-aminobutyric acid was lower in the tissues of the bacterium-treated seeds than in the control seeds. Smaller quantities of gamma-aminobutyric acid were seen in both the exudate and tissues of the E. cloacae CAL3-treated seeds than in the control seeds.

Amino Acids, Cyclic↗
PubMed1971

Lateral transport of ions into the xylem of corn roots: I. Kinetics and energetics.

A technique is described for study of the kinetics of lateral transport of ions across single roots of corn, Zea mays, in short term experiments under steady state conditions. The kinetics of chloride transfer to the vessels reflected the kinetics of absorption of chloride by the root cells. Efflux from the root vacuoles contributed to only a small extent to transport of chloride into the exudate. Lateral transport of chloride was inhibited by bromide at chloride concentrations in the ranges of both mechanisms 1 and 2 in a manner implicating competition. The uncoupler carbonylcyanide m-chlorophenylhydrazone used at 1 mum caused transfer of chloride to cease almost immediately at both low and high concentrations of chloride. Oligomycin depressed transport of chloride to the vessels within 10 to 15 minutes after application at 2 micrograms per milliliter. Inhibition by oligomycin was 75% at 0.5 mm chloride and 55% at 5 mm.It is concluded that lateral transport of chloride across corn roots is mediated by the dual mechanisms of ion absorption which reside in the plasmalemma. Transfer of chloride is inhibited by bromide and depends upon ATP as energy source. Chloride moves from the plasmalemma, the site of carriermediated absorption, to the xylem vessels by way of the symplasm. There is no evidence in these experiments that lateral transport of chloride in corn roots is governed by diffusion at any concentrations of chloride used in these experiments.

Journal Article↗
PubMed1990

Identification and characterization of a functional nodD gene in Azorhizobium caulinodans ORS571.

Azorhizobium caulinodans ORS571, a bacterium capable of nodulating roots and stems of the tropical legume Sesbania rostrata, has been shown to have no nodD-like gene located immediately upstream from its common nodABC locus. A clone carrying a functional nodD gene of strain ORS571 has now been isolated from a pLAFR1 gene library by screening for naringenin-induced expression of the common nod genes in an Agrobacterium background. Tn5 mutagenesis of the cloned insert DNA delimited the inducing activity to a +/- 0.8-kilobase-pair fragment. One of the Tn5 insertions in the activator locus was homogenotized in the ORS571 genome. This resulted in a mutant strain (ORS571-3) that was unable to induce common nod gene expression in the presence of host plant exudate or the flavanone naringenin and that had lost the capacity to nodulate the roots and stems of S. rostrata. Complementation of both mutant phenotypes was achieved upon introduction of the cloned nodD gene. Sequencing of the nodD locus indicated the presence of a single, 942-base-pair-long open reading frame (ORFD) with significant homology to the nodD gene of (brady)rhizobia. The level of homology, however, is the lowest thus far reported for this kind of gene. ORFD most likely initiates translation with a TTG start codon. Upstream from ORFD, a divergently oriented nod box-like sequence is present, the function of which remains to be determined.

Amino Acid Sequence↗
PubMed1966

Removal of salt from xylem sap by leaves and stems of guttating plants.

Although root pressure and guttation presumably result from a high concentration of salt in the root xylem, the guttation fluid is very dilute. Measurements of the osmotic potential of the guttation liquid and of exudates at various levels in guttating plants indicate that salt is removed from the xylem in the upper part of plants, particularly in the leaves. The concentration of salt solutions forced through individual leaves by an artificial root pressure has no influence on the osmotic potential of the guttation fluid. This suggests that leaves play an important role in removing salt from the xylem of guttating plants.

Journal Article↗
PubMed1997

Modification of rhizobacterial populations by engineering bacterium utilization of a novel plant-produced resource.

The ability to catabolize distinct nutrients produced by a plant may be a factor in the successful colonization of that host by a bacterium when in competition with other rhizosphere microorganisms. We tested this hypothesis by examining the influence of a novel substrate produced by a transgenic plant on root colonization by near-isogenic bacteria, differing only in their ability to use the resource. When inoculated alone, both bacteria colonized the roots of the normal and transgenic plants with equal kinetics and to indistinguishable levels. When the two bacteria were coinoculated, the catabolizer reached a population density significantly higher than that of the noncatabolizer on the roots of the resource-producing plant. No such advantage was observed on the roots of normal plants. These results support the theory that resources produced and exuded by a plant host can confer a selective advantage to microorganisms that use the substrate.

Agrobacterium tumefaciens↗
PubMed1994

Effects of a supersaturated pulpal fluid on the formation of caries-like lesions on the roots of human teeth.

Root surfaces were exposed to demineralizing buffer in a continuous-flow system, with or without simultaneous perfusion of the pulp chamber with a supersaturated surrogate dentine fluid (SDF). Experimental lesions formed with perfusion of the pulp were significantly less deep than control lesions formed without perfusion, but the application of hydrostatic pressure to the SDF (15 or 30 cm water) did not produce significantly greater reductions. The lesion depth reduction was attributed to reduced undersaturation at the advancing lesion front through interdiffusion of the demineralizing buffer and the SDF. Translucent bands, resembling sclerotic dentine, were observed beneath 9 of 24 experimental lesions and 5 of 24 control lesions. Scanning electron microscopy showed that, in most of the bands beneath experimental lesions, dentinal tubules were either partly occluded by granular mineral deposits or were reduced in diameter. Thus, in vivo, dentine fluid may modify the rate of lesion progression and promote sclerosis in the underlying dentine.

Acetates↗
PubMed1980

Effect of valinomycin and gramicidin d on the reflection coefficient of soybean root systems.

Valinomycin and gramicidin D were used to test the hypothesis that a lipoprotein membrane is the osmotic barrier in mature root systems. Hydroponically grown soybean (var. Ranson) root systems were pressurized in steps between 0.2 and 5.0 bars at 25 C. Steady-state flow rates and exudate osmotic potentials were measured at each pressure. Valinomycin or gramicidin D to a final concentration of 2.6 or 5.0 micromolar, respectively, was injected into the nutrient solution, and steady-state values were again measured between 0.2 and 5.0 bars. Both ionophores reduced the x intercept of the straight line portion of the flux rate versus pressure curve, and increased the exudate osmotic potential at infinite flow rate. Valinomycin lowered the reflection coefficient from 0.91 to 0.76, whereas gramicidin D lowered the reflection coefficient from 0.86 to 0.81. The results support the hypothesis that one or more lipoprotein membranes in the root system function in regulation of ion movement from the ambient solution to the stele during high transpiration rates.

Journal Article↗
PubMed2006

Nonsurgical treatment of extensive cyst-like periapical lesion of endodontic origin.

AIM: To report the repair of an extensive periapical lesion of endodontic origin, following nonsurgical treatment. SUMMARY: Clinical and radiographic examination revealed an extensive periapical lesion related to tooth 22, extending from the distal surface of tooth 21 to the mesial surface of 26. The patient reported a previous history of dental trauma involving this quadrant and had been under orthodontic treatment for a year. Intraoral examination revealed an asymptomatic bony hard swelling, mainly confined to the palate. During root canal exploration irregular walls associated with 3 mm of apical calcification were noted. After apical patency was obtained 1 mL of bloody serous exudate was drained. Intracanal aspiration provided a further 2 mL of yellow serous exudate. Following biomechanical preparation, a dressing of calcium hydroxide with anaesthetic solution was applied and replaced four times over a period of 12 months. The clinical-pathological picture demonstrated resolution of the lesion during this period of time. The 14-month clinical and radiographic examinations revealed normal bony contour and a significant resolution of the maxillary radiolucency. KEY LEARNING POINTS: Periapical lesions of endodontic origin may develop asymptomatically and become large. Proper biomechanical preparation followed by calcium hydroxide medication renewed periodically represents a nonsurgical approach to resolve extensive inflammatory periapical lesions.

Adult↗
PubMed2006

Organic anion exudation by ectomycorrhizal fungi and Pinus sylvestris in response to nutrient deficiencies.

Low molecular weight organic anions (LMWOA) can enhance weathering of mineral grains. We tested the hypothesis that ectomycorrhizal (EcM) fungi and tree seedlings increase their exudation of LMWOA when supply of magnesium, potassium and phosphorus is low to enhance the mobilization of Mg, K and P from mineral grains. Ectomycorrhizal fungi and Pinus sylvestris seedlings were cultured in symbiosis and in isolation on glass beads with nutrient solution or with sand as a rooting medium, with a complete nutrient supply or with Mg, K, P or N in low supply. Concentrations of all dicarboxylic LMWOA in the rooting medium were measured. Nonmycorrhizal seedlings released predominantly malonate. Colonization with Hebeloma longicaudum decreased the amount of organic anions exuded, whereas Paxillus involutus and Piloderma croceum increased the concentration of oxalate but not the total amount of LMWOA. Phosphorus deficiency increased the concentration of LMWOA by nonmycorrhizal and EcM seedlings. Magnesium deficiency increased the concentration of oxalate by nonmycorrhizal and EcM seedlings, but not the concentration of total LMWOA. Paxillus involutus grown in pure culture responded differently to low nutrient supply compared with symbiotic growth. Ectomycorrhizal fungi did not increase the total concentration of LMWOA compared with nonmycorrhizal seedlings but, depending on the fungal species, they affected the type of LMWOA found.

Anions↗
PubMed2001

Uptake and translocation of carpropamid in rice (Oryza sativa L).

Translocation of the antiblast compound, carpropamid, was investigated in rice using [14C]carpropamid. When applied to the seed, carpropamid was not only readily absorbed but was translocated to different parts of the seedlings emerging from treated seeds. A substantial portion of fungicide appeared to be exuded onto the leaf surface. In 21-day-old plants grown from [14C]carpropamid-treated seeds, 27.2% of the radioactivity isolated from leaves was present on the surface of lamina. This exuded fraction is probably responsible for its action as a fungal anti-penetrant compound. Following 30-min root dipping of 14-day-old seedlings, carpropamid was rapidly absorbed and translocated throughout the seedling. Its intra-laminar distribution was uniform as determined by autoradiography. Only a small fraction (< 2%) of fungicide applied to the foliage was translocated beyond the site of application within the treated leaf. Translocation was primarily apoplastic. Approximately 54% of the radioactivity recovered from leaves was in the form of carpropamid. At least seven radiolabelled metabolic products were observed by TLC. Only 8.3% of radioactivity applied through the seeds could be recovered from 21-day-old seedlings.

Amides↗
PubMed2006

Antioxidant activity of medicinal plant polysaccharides.

Eleven polysaccharides have been isolated from the leaves of Arctium lappa var. herkules, Aloe barbadensis, Althaea officinalis var. robusta, Plantago lanceolata var. libor, aerial parts and roots of Rudbeckia fulgida var. sullivantii, stems of Mahonia aquifolium, and peach-tree (Prunus persica) gum exudates. The polysaccharides were investigated for their ability to inhibit peroxidation of soyabean lecithin liposomes by OH radicals. The highest inhibition was found with glucuronoxylans of A. officinalis var. robusta and P. lanceolata var. libor, aerial parts. Their antioxidant activity accounted for approximately 69% of the activity of the reference compound alpha-tocopherol. The activity of eight polysaccharides ranged from 20 to 45%, while the fructofuranan from P. lanceolata var. libor roots was practically inactive.

Antioxidants↗
PubMed2002

Speciation of iron coordinated by phytosiderophores by use of HPLC with pulsed amperometric detection and AAS.

Phytosiderophores of the mugineic acid family, and the respective iron species, have been separated by anion-exchange chromatography with NaOH gradient elution. Two different detection methods were used in parallel, pulsed amperometry (PAD) for phytosiderophores and atomic absorption spectrometry (AAS) for iron. This combination enables identification of separated iron species. Up to five different iron species were separated and detected within 30 min - two different phytosiderophore species, two amino acid species, and one species which has not yet been identified but which is most probably a decomposition product of phytosiderophores. The detection limit was in the low micro mol L(-1) concentration range, which is sufficiently low for determination in real plant samples, even after dilution. The method has been applied to root washings of iron-deficient wheat and barley plants and to a xylem exudate of non-deficient maize.

Chromatography, High Pressure Liquid↗
PubMed1989

Effects of migrating Gasterophilus intestinalis larvae (Diptera: Gasterophilidae) on the mouth of the horse.

Lesions were formed in the mouth of the horse by first- and second-stage Gasterophilus intestinalis larvae. The lesions resulted as larvae burrowed through the top millimeter of the tongue and then became embedded in the interdental gingiva. Appearance of the lesion was dependent on the degree of larval burrowing activity and healing that had taken place. Active tunneling production occurred at the posterior end of the lesion. Extensive change in configuration and color was apparent along the longer lesions with active larvae. Virtually all tissue in the path of the larvae was removed while forming a tunnel. Tissue destroyed included tops of the lamina propria mucosae evaginations and the deeper portions of the lamina epithelialis mucosae. Histopathologic findings showed that the tissue removed included the nerve and blood supply of the proprial evaginations. Hemorrhage and exocytosis into the tunnels included erythrocytes mixed with some macrophages, lymphocytes and scant numbers of eosinophils. Air shafts excavated in the tongue by larvae enabled bacteria to enter into the tunnels. Bacteria became adhered to larvae and initiated microabscesses. Microabscesses were composed of clotted erythrocytes, bacteria, disintegrating epithelial cells, and large numbers of neutrophils. Cells surrounding the tunnel exhibited pyknosis, epithelial hydropic degeneration and became separated from each other. Healing of tongue lesions occurred as epithelial cell growth below raised the tunnel upward and affected tissue desquamated. Interdental gingiva invaded by larvae were hyperemic and denuded of epithelia. Recession and ulceration of the gingiva produced periodontal pockets. Extensive invasion by larvae led to compound periodontal pockets. Larval mouth hooks were embedded in the submucosa of the pockets and tore at engorged capillaries. The cephalic portion of embedded larvae became surrounded by a cellular exudate containing erythrocytes and mononuclear cells. Attachment of second-stage larvae at the root of the tongue did not produce observable damage.

Animals↗
PubMed1975

Structure and actions of saikosaponins isolated from Bupleurum falcatum L. I. Anti-inflammatory action of saikosaponins.

Anti-inflammatory action of saikosaponins isolated from the root of Bupleurum falcatum L were examined using female albino rats. The anti-exudative action by granuloma pouch method and the antigranulomatous action by cotton pellet method were demonstrated with i.m. and oral administrations of saikosaponins. The oral administration of saikosaponins in 10 times the dosage of i.m. injection showed almost the same effect. Among saikosaponins isolated from Bupleurum falcatum, saikosaponins a and d, not c, were demonstrated to have anti-inflammatory action. The relationship between structure and action of saikosaponins was discussed. No changes in body weight, adrenal weight, plasma-11-OH-corticosteroid level and hematocrit value were observed.

11-Hydroxycorticosteroids↗