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PubMed2005

The effect of endodontic therapy on periapical exudate neutrophil elastase and prostaglandin-E2 levels.

This study aimed to investigate periapical exudate neutrophil elastase (NE) and prostaglandin E2 (PGE2) levels and their relationships with clinical symptoms, and to determine the changes of their levels following first treatment visit. Periapical exudate samples were collected from the canals of 34 nonvital single-rooted teeth at two sequential treatment visits. Periapical exudate NE and PGE2 levels were found to be higher in the presence of clinical symptoms (pus discharge, swelling) (p < 0.05). The canals of teeth with larger periapical radiolucent area (>or=1 cm) contained more PGE2 levels than with smaller ones (<1 cm) (p < 0.05). Periapical exudate NE levels were significantly correlated with PGE2 levels (p < 0.05), and their levels at first treatment visit did not change following root canal therapy (p > 0.05). The periapical exudate NE and PGE2 levels may regulate periapical disease expression, but the results of this study were unable to reveal this association.

Adult↗

PubMed1996

Induction of Rhizobium meliloti nodC gene by Alnus incana compounds.

An expression of nodC promoter of R. meliloti 1021, cloned in front of the Escherichia coli lacZ gene, was used to study the presence of R. meliloti nodC gene-inducing compound(s) in extracts and exudates of A. incana seeds and roots. The regulatory gene nodD was expressed at comparable level in bacterial culture of R. meliloti with and without the studied plant extracts and exudates, whereas the nodC-lacZ fusion expression was increased 4 times by seed exudates of grey alder and 2 times by seed extracts and root ingredients in comparison to the nodC-lacZ fusion expression in R. meliloti grown in a medium free of plant compounds. Induction of R. meliloti nodC gene expression by A. incana substances was also supported in plant test. Sterile filtrate of coculture of R. meliloti with seed exudates of A. incana induced root hair deformations and nodule-like structures on Medicago sativa.

Bacterial Proteins↗

PubMed2004

[Ciliary body melanomas. Survival and prognostic aspects after brachytherapy or proton therapy].

INTRODUCTION: Our main goals were to study the survival of patients with uveal melanomas involving the ciliary body 5 and 10 years after treatment and to review prognosis. MATERIAL AND METHODS: This study investigated 106 tumors (27 ciliary body melanomas and 79 choroidal-ciliary melanomas) of patients treated between June 1983 and April 1998. Seventy-two patients were treated with 106-ruthenium applicators and 34 were treated with proton therapy. Some large tumors or recurrences required a second treatment. The mean follow-up period was 91 months. RESULTS: The mean tumor sizes before treatment were 6,6mm for melanoma thickness and 10.3mm for mean largest basal melanoma diameters (LTD). Of the patients studied, 71% were still alive at 5 years, 35% had metastasis and 27.7% developed recurrences. Multivariate analysis showed that the risk factors for melanoma-related death were LTD greater than 13mm, presence of exudative retinal detachment, macroscopic iris root involvement at the time of diagnosis, and choroidal-ciliary location. DISCUSSION AND CONCLUSION: With 71% of patients still alive at 5 years, this review shows that melanomas involving the ciliary body do not seem less severe than more posterior uveal tumors. Because of size differences between ciliary body melanomas and choroidal-ciliary melanomas, we cannot come to the conclusion that choroidal-ciliary melanomas have a poorer prognosis than ciliary body melanomas. Largest tumor diameter over 13mm, presence of exudative retinal detachment, and macroscopic iris root involvement at the time of diagnosis are important risk factors for melanoma-related death, as shown by the multivariate analysis.

Adolescent↗

PubMed2006

Rhizosphere carboxylate concentrations of chickpea are affected by soil bulk density.

We investigated whether carboxylate exudation by chickpea (Cicer arietinum L.) was affected by soil bulk density and if this effect was local or systemic. We hypothesised that concentrations of carboxylates would increase with distance from the root apex due to continuous and constitutive accumulation of carboxylates, and that exudate accumulation would be greater in a compacted soil than in a loose soil. Plants were grown in split-root or single cylinders containing loose (1400 kg m (-3)) or compacted (1800 kg m (-3)) soil. Rhizosphere carboxylate concentrations were measured of whole root systems as well as of sections along the root. The root diameter was greatest of plants grown in the compacted soil; however, root diameters were the same for both root halves in the split-root design, whether they grew in loose soil or in compacted soil. Similarly, carboxylate concentrations tended to be lower for the whole root system in the compacted soil, but were the same for both root halves in the split-root design, irrespective of whether the roots were in loose soil or in compacted soil. These results indicate that both root diameter and carboxylate exudation by roots in chickpea is regulated systemically via a signal from the shoot rather than by local signals in the roots. There was no accumulation of carboxylates with increasing distance from the apex, probably because microbial degradation occurred at similar rates as carboxylate exudation. Malonate, previously suggested as deterrent to microorganisms, is likely only a selective deterrent.

Carboxylic Acids↗

PubMed1966

Wounding Response in Relation to Polar Transport of Radiocalcium in Isolated Root Segments of Zea mays.

A perfusion bridge technique is described which permits the continuous collection of exudations from both ends of corn root segments. By exposing the central portion of the segments to radiocalcium, the amounts and rates of tracer movement in either direction may be determined. Typically, a peak in both acropetal and basipetal transport occurs at about 90 minutes after exposure to tracer. This transport peak is followed by a sharp decline to relatively low transport rates. Thereafter the 2 perfusates from opposite ends of a segment pair show significant differences. The acropetal increments decrease somewhat erratically to 0 at 10 to 12 hours, while the basipetal increments steadily increase to a steady-state value which remains constant from 8 to 24 hours. After a segment pair has reached steady-state polar transport, a fresh cut on the apical ends causes the resumption of acropetal transport. Such response suggests that polar transport in these root segments is at least partially a wound response. A possible explanation of the complex transport behavior is advanced.

Journal Article↗

PubMed2004

Phytotoxic and antimicrobial activities of catechin derivatives.

(+/-)-Catechin is a potent phytotoxin, with the phytotoxicity due entirely to the (-)-catechin enantiomer. (+)-Catechin, but not the (-)-enantiomer, has antibacterial and antifungal activities. Tetramethoxy, pentaacetoxy, and cyclic derivatives of (+/-)-catechin retained phytotoxicity. The results indicate that antioxidant properties of catechins are not a determining factor for phytotoxicity. A similar conclusion was reached for the antimicrobial properties. Centaurea maculosa (spotted knapweed) exudes (+/-)-catechin from its roots, but the flavanol is not re-absorbed and hence the weed is not affected. The much less polar tetramethoxy derivative may, however, be absorbed and hence be able to cause toxicity. Because of the combination of phytotoxicity and antimicrobial activity, (+/-)-catechin could be a useful natural herbicide and antimicrobial.

Anti-Bacterial Agents↗

PubMed2002

A receptor kinase gene regulating symbiotic nodule development.

Leguminous plants are able to establish a nitrogen-fixing symbiosis with soil bacteria generally known as rhizobia. Metabolites exuded by the plant root activate the production of a rhizobial signal molecule, the Nod factor, which is essential for symbiotic nodule development. This lipo-chitooligosaccharide signal is active at femtomolar concentrations, and its structure is correlated with host specificity of symbiosis, suggesting the involvement of a cognate perception system in the plant host. Here we describe the cloning of a gene from Medicago sativa that is essential for Nod-factor perception in alfalfa, and by genetic analogy, in the related legumes Medicago truncatula and Pisum sativum. The identified 'nodulation receptor kinase', NORK, is predicted to function in the Nod-factor perception/transduction system (the NORK system) that initiates a signal cascade leading to nodulation. The family of 'NORK extracellular-sequence-like' (NSL) genes is broadly distributed in the plant kingdom, although their biological function has not been previously ascribed. We suggest that during the evolution of symbiosis an ancestral NSL system was co-opted for transduction of an external ligand, the rhizobial Nod factor, leading to development of the symbiotic root nodule.

Amino Acid Motifs↗

PubMed1993

Microgradients of microbial oxygen consumption in a barley rhizosphere model system.

A microelectrode technique was used to map the radial distribution of oxygen concentrations and oxygen consumption rates around single roots of 7-day-old barley seedlings. The seedlings were grown in gel-stabilized medium containing a nutrient solution, a soil extract, and an inert polymer. Oxygen consumption by microbial respiration in the rhizosphere (<5 mm from the root) and in bulk medium (>30 mm from the root) was determined by using Fick's laws of diffusion and an analytical approach with curve fitting to measured microprofiles of oxygen concentration. A marked increase of microbial respiration was observed in the inner 0- to 3-mm-thick, concentric zone around the root (rhizosphere). The volume-specific oxygen consumption rate (specific activity) was thus 30 to 60 times higher in the innermost 0 to 0.01 mm (rhizoplane) than in the bulk medium. The oxygen consumption rate in the root tissue was in turn 10 to 30 times higher than that in the rhizoplane. Both microbial respiration and oxygen uptake by the root varied between different roots. This was probably due to a between-root variation of the exudation rate for easily degradable carbon compounds supporting the microbial oxygen consumption.

Journal Article↗

PubMed1988

Carbon Cost of the Fungal Symbiont Relative to Net Leaf P Accumulation in a Split-Root VA Mycorrhizal Symbiosis.

Translocation of (14)C-photosynthates to mycorrhizal (+ +), half mycorrhizal (0+), and nonmycorrhizal (00) split-root systems was compared to P accumulation in leaves of the host plant. Carrizo citrange seedlings (Poncirus trifoliata [L.] Raf. x Citrus sinensis [L.] Osbeck) were inoculated with the vesicular-arbuscular mycorrhizal fungus Glomus intraradices Schenck and Smith. Plants were exposed to (14) CO(2) for 10 minutes and ambient air for 2 hours. Three to 4% of recently labeled photosynthate was allocated to metabolism of the mycorrhiza in each inoculated root half independent of shoot P concentration, growth response, and whether one or both root halves were colonized. Nonmycorrhizal roots respired more of the label translocated to them than did mycorrhizal roots. Label recovered in the potting medium due to exudation or transport into extraradical hyphae was 5 to 6 times greater for (+ +) versus (00) plants. In low nutrient media, roots of (0+) and (+ +) plants transported more P to leaves per root weight than roots of (00) plants. However, when C translocated to roots utilized for respiration, exudation, etc., as well as growth is considered, (00) plant roots were at least as efficient at P uptake (benefit) per C utilized (cost) as (0+) and (+ +) plants. Root systems of (+ +) plants did not supply more P to leaves than (0+) plants in higher nutrient media, yet they still allocated twice the (14)C-photosynthate to the mycorrhiza as did (0+) root systems. This indicates there is an optimal level of mycorrhizal colonization above which the plant receives no enhanced P uptake yet continues to partition photosynthates to metabolism of the mycorrhiza.

Journal Article↗

PubMed1972

Transport of sodium into the xylem exudate of tobacco.

When tobacco (Nicotiana tabacum L. var. Virginia Gold) plants were pretreated with Na ((22)Na) several days before detopping, from 2.3 to 4.9% of Na previously accumulated in roots appeared in the xylem exudate in 7 days after detopping. Na from the external medium, however, was readily transported to the exudate. Moreover, the amount of the pretreatment Na that was transported to the exudate was not influenced by the presence of Na in the external medium. When Na was present in the external medium after detopping, about 4% (with an NaNO(3) post treatment) to 10% (with an NaCl post treatment) of the Na transported to the xylem in the 7 days following detopping originated in the vacuoles. Nitrate salts of K or Na in the external medium after detopping resulted in transport of large quantities of the respective cation to the exudate, but not in increased transport of the pretreatment Na. A much larger percentage of the K that was accumulated after detopping than of the Na similarly accumulated was transferred to the xylem exudate.

Journal Article↗

PubMed2004

Active nonsurgical decompression of large periapical lesions--3 case reports.

This paper describes a new nonsurgical approach for treating large periapical lesions which involves using a modified vacuum system within the root canal space. This new technique produces a vacuum effect in the periapical zone, which facilitates evacuation of large amounts of inflammatory fluids. This technique was used in 3 clinical cases, in which the patients presented with copious amounts of exudate draining from within the root canals. Clinical and radiographic results showed long-term resolution of the endodontic lesions. This treatment of the periapical pathology was consistent with the principles of conservative, nonsurgical endodontic procedures.

Adolescent↗

PubMed1999

Linking development and determinacy with organic acid efflux from proteoid roots of white lupin grown with low phosphorus and ambient or elevated atmospheric CO2 concentration

White lupin (Lupinus albus L.) was grown in hydroponic culture with 1 &mgr;M phosphorus to enable the development of proteoid roots to be observed in conjunction with organic acid exudation. Discrete regions of closely spaced, determinate secondary laterals (proteoid rootlets) emerged in near synchrony on the same plant. One day after reaching their final length (4 mm), citrate exudation occurred over a 3-d pulse. The rate of exudation varied diurnally, with maximal rates during the photoperiod. At the onset of citrate efflux, rootlets had exhausted their apical meristems and had differentiated root hairs and vascular tissues along their lengths. Neither in vitro phosphoenolpyruvate carboxylase nor citrate synthase activity was correlated with the rate of citrate exudation. We suggest that an unidentified transport process, presumably at the plasma membrane, regulates citrate efflux. Growth with elevated (700 &mgr;L L-1) atmospheric [CO2] promoted earlier onset of rootlet determinacy by 1 d, resulting in shorter rootlets and citrate export beginning 1 d earlier as a 2-d diurnal pulse. Citrate was the dominant organic acid exported, and neither the rate of exudation per unit length of root nor the composition of exudate was altered by atmospheric [CO2].

Journal Article↗

PubMed2001

A patch-clamp study on the physiology of aluminum toxicity and aluminum tolerance in maize. Identification and characterization of Al(3+)-induced anion channels.

The presence of Al(3+) in the rhizosphere induces citrate efflux from the root apex of the Al-tolerant maize (Zea mays) hybrid South American 3, consequently chelating and reducing the activity of toxic Al(3+) at the root surface. Because citrate is released from root apical cells as the deprotonated anion, we used the patch-clamp technique in protoplasts isolated from the terminal 5 mm of the root to study the plasma membrane ion transporters that could be involved in Al-tolerance and Al-toxicity responses. Acidification of the extracellular environment stimulated inward K(+) currents while inhibiting outward K(+) currents. Addition of extracellular Al(3+) inhibited the remaining K(+) outward currents, blocked the K(+) inward current, and caused the activation of an inward Cl(-) current (anion efflux). Studies with excised membrane patches revealed the existence of Al-dependent anion channels, which were highly selective for anions over cations. Our success in activating this channel with extracellular Al(3+) in membrane patches excised prior to any Al(3+) exposure indicates that the machinery required for Al(3+) activation of this channel, and consequently the whole root Al(3+) response, is localized to the root-cell plasma membrane. This Al(3+)-activated anion channel may also be permeable to organic acids, thus mediating the Al-tolerance response (i.e. Al-induced organic acid exudation) observed in intact maize root apices.

Aluminum↗

PubMed1980

Comparison of the levels of six endogenous gibberellins in roots and shoots of spinach in relation to photoperiod.

This communication describes the distribution of gibberellins (GAs) in roots and shoots of spinach in relation to photoperiod. From previous work (Metzger, Zeevaart 1980 Plant Physiol 65: 623-626) shoots were known to contain GA(53), GA(44), GA(19), GA(17), GA(20), and GA(29). We now show by combined gas chromatography-mass spectrometry that roots contain GA(44), GA(19), and GA(29). Trace amounts of GA(53) were detected by combined gas chromatography-selected ion current monitoring. Neither GA(17) nor GA(20) were detected in root extracts. Analysis by the d-5 corn bioassay also showed no effect of photoperiodic treatment on the levels of GA-like substances in root extracts. Both phloem and xylem exudates had patterns of GA-like activity similar to those found in shoots and roots, respectively. Moreover, foliar application of [(3)H]GA(20) resulted in the transport of label from the shoot to the roots. Over half of the label in the roots represented unmetabolized [(3)H]GA(20), indicating that part of the GA(20) in the phloem is transported to the roots. Consequently, if GA(20) is made in, or transported to the roots, it is rapidly metabolized in that organ. This is a clear indication that regulation of GA metabolism is greatly different in roots and shoots.

Journal Article↗

PubMed2003

Evaluation of sesquiterpene lactone fraction of Saussurea lappa on transudative, exudative and proliferative phases of inflammation.

The sesquiterpene lactone fraction of Saussurea lappa roots was evaluated for its effect on the transudative, exudative and proliferative phases of inflammation using the cotton pellet granuloma assay in rats. The fraction (25-100 mg/kg, p.o.) showed significant dose-dependent inhibition of the increase in wet weight of the cotton pellet at 3 h (transudative phase), leakage of dye from the bloodstream around granuloma at 24 h (exudative phase) and increase in dry weight of the cotton pellet on day 6 (proliferative phase). It significantly lowered the elevated biochemical parameters such as alkaline phosphatase, acid phosphatase, gamma-glutamyltranspeptidase and significantly elevated the lowered albumin concentration in serum. The studies suggest that the antiinflammatory activity of the sesquiterpene lactone fraction of S. lappa may, in part, be due to stabilization of lysosomal membranes and an antiproliferative effect.

Acid Phosphatase↗

PubMed1967

Translocation of manganese, iron, cobalt, and zinc in tomato.

Tomato plants in solution culture were treated with 0 to 50 mum Mn, Co, or Zn in the presence of 5 mum Fe. Stem exudates were analyzed to determine quantities and forms of the metals translocated.Mn had no effect on exudate volume. Co and Zn at 5 mum and above depressed exudate volumes. Nutrient Mn was concentrated 2 to 5 times in the exudates. Co and Zn concentrations were between 1 and 3.Tomato roots treated with 0 to 10 mum Mn released into the exudate an average of 29% of the Fe they absorbed. They released 21% of the absorbed Fe when treated with 50 mum Mn. On 50 mum Co or Zn, the roots released only about 1% of the absorbed Fe.The exudates contained 12 to 47 mum citrate, which was usually considerably in excess of Fe. Electrophoresis of exudate revealed Fe as the only metal in anionic form. Mn, Co, and Zn migrated as cations.The concentration of Ca was >3 mm and Mg >1.5 mm in the exudates. Estimates based on metal-citrate equilibrium constants and constants of metal displacement caused by Ca and Mg confirmed that Mn, Co, and Zn were transported predominantly as inorganic cations in the stem exudates.

Journal Article↗

PubMed2025

Dynamic Rhizodeposition in the Woody Perennial Populus trichocarpa.

Plants undergo physiological and metabolic changes that release specific molecules into the surrounding soil, a process collectively known as rhizodeposition. These compounds play crucial roles in plant-microbe-soil interactions, such as supporting plant development and resilience in changing environments. Under nutrient-limited conditions, these plant-derived compounds modify the rhizosphere environment, mobilizing otherwise inaccessible nutrients and recruiting stress-adaptive microbial communities that support stress resilience. Currently, the chemical diversity of rhizodeposition has yet to be fully realized but is expected to be a complex mixture that includes soluble organic compounds excreted from root cells, along with products of root cell turnover, sloughed-off root cap and border cells, and mucilage. Here, we developed a methodological and conceptual framework for an in-depth measurement of rhizodeposition through critical advancements in untargeted metabolomics. This approach provided foundational insights into the dynamic changes in rhizodeposition for the woody perennial Populus trichocarpa and rhizodeposit profiles varying by genotype, time, location, and environment. More broadly, this study provides a framework that will help formulate the next steps to effectively study rhizodeposition.

Populus↗

PubMed1992

Chemotaxis of Rhizobium meliloti towards Nodulation Gene-Inducing Compounds from Alfalfa Roots.

Luteolin, a flavone present in seed exudates of alfalfa, induces nodulation genes (nod) in Rhizobium meliloti and also serves as a biochemically specific chemoattractant for the bacterium. The present work shows that R. meliloti RCR2011 is capable of very similar chemotactic responses towards 4',7-dihydroxyflavone, 4',7-Dihydroxyflavanone, and 4,4'-dihydroxy-2-methoxychalcone, the three principal nod gene inducers secreted by alfalfa roots. Chemotactic responses to the root-secreted nod inducers in capillary assays were usually two- to four-fold above background and, for the flavone and flavonone, occurred at concentrations lower than those required for half-maximal induction of the nodABC genes. Complementation experiments indicated that the lack of chemotactic responsiveness to luteolin seen in nodD1 and nodA mutants of R. meliloti was not due to mutations in the nod genes, as previously thought. Thus, while nod gene induction and flavonoid chemotaxis have the same biochemical specificity, these two functions appear to have independent receptors or transduction pathways. The wild-type strain was found to suffer selective, spontaneous loss of chemotaxis towards flavonoids during laboratory subculture.

Journal Article↗