Vertical root fractures and their management

PubMed Central

Khasnis, Sandhya Anand; Kidiyoor, Krishnamurthy Haridas; Patil, Anand Basavaraj; Kenganal, Smita Basavaraj

2014-01-01

Vertical root fractures associated with endodontically treated teeth and less commonly in vital teeth represent one of the most difficult clinical problems to diagnose and treat. In as much as there are no specific symptoms, diagnosis can be difficult. Clinical detection of this condition by endodontists is becoming more frequent, where as it is rather underestimated by the general practitioners. Since, vertical root fractures almost exclusively involve endodontically treated teeth; it often becomes difficult to differentiate a tooth with this condition from an endodontically failed one or one with concomitant periodontal involvement. Also, a tooth diagnosed for vertical root fracture is usually extracted, though attempts to reunite fractured root have been done in various studies with varying success rates. Early detection of a fractured root and extraction of the tooth maintain the integrity of alveolar bone for placement of an implant. Cone beam computed tomography has been shown to be very accurate in this regard. This article focuses on the diagnostic and treatment strategies, and discusses about predisposing factors which can be useful in the prevention of vertical root fractures. PMID:24778502

Circular zig-zag scan video format

DOEpatents

Peterson, C. Glen; Simmons, Charles M.

1992-01-01

A circular, ziz-zag scan for use with vidicon tubes. A sine wave is generated, rectified and its fourth root extracted. The fourth root, and its inverse, are used to generate horizontal ramp and sync signals. The fourth root is also used to generate a vertical sync signal, and the vertical sync signal, along with the horizontal sync signal, are used to generate the vertical ramp signal. Cathode blanking and preamplifier clamp signals are also obtained from the vertical sync signal.

[Vertical fractures: apropos of 2 clinical cases].

PubMed

Félix Mañes Ferrer, J; Micò Muñoz, P; Sánchez Cortés, J L; Paricio Martín, J J; Miñana Laliga, R

1991-01-01

The aim of the study is to present a clinical review of the vertical root fractures. Two clinical cases are presented to demonstrates the criteria for obtaining a correct diagnosis of vertical root fractures.

Graviresponsiveness of surgically altered primary roots of Zea mays

NASA Technical Reports Server (NTRS)

Maimon, E.; Moore, R.

1991-01-01

We examined the gravitropic responses of surgically altered primary roots of Zea mays to determine the route by which gravitropic inhibitors move from the root tip to the elongating zone. Horizontally oriented roots, from which a 1-mm-wide girdle of epidermis plus 2-10 layers of cortex were removed from the apex of the elongating zone, curve downward. However, curvature occurred only apical to the girdle. Filling the girdle with mucilage-like material transmits curvature beyond the girdle. Vertically oriented roots with a half-girdle' (i.e. the epidermis and 2-10 layers of the cortex removed from half of the circumference of the apex of the elongating zone) curve away from the girdle. Inserting the half-girdle at the base of the elongating zone induces curvature towards the girdle. Filling the half-circumference girdles with mucilage-like material reduced curvature significantly. Stripping the epidermis and outer 2-5 layers of cortex from the terminal 1.5 cm of one side of a primary root induces curvature towards the cut, irrespective of the root's orientation to gravity. This effect is not due to desiccation since treated roots submerged in water also curved towards their cut surface. Coating a root's cut surface with a mucilage-like substance minimizes curvature. These results suggest that the outer cell-layers of the root, especially the epidermis, play an important role in root gravicurvature, and the gravitropic signals emanating from the root tip can move apoplastically through mucilage.

Circular zig-zag scan video format

DOEpatents

Peterson, C.G.; Simmons, C.M.

1992-06-09

A circular, ziz-zag scan for use with vidicon tubes is disclosed. A sine wave is generated, rectified and its fourth root extracted. The fourth root, and its inverse, are used to generate horizontal ramp and sync signals. The fourth root is also used to generate a vertical sync signal, and the vertical sync signal, along with the horizontal sync signal, are used to generate the vertical ramp signal. Cathode blanking and preamplifier clamp signals are also obtained from the vertical sync signal. 10 figs.

Oral cutaneous sinus tract, vertical root fracture, and bisphosphonate-related osteonecrosis: a case report.

PubMed

Wigler, Ronald; Steinbock, Nelly; Berg, Tal

2013-08-01

Oral cutaneous sinus tracts (OCSTs) of dental origin are often initially misdiagnosed and inappropriately treated. Accurate diagnosis is especially important in cases of bisphosphonate (BP) therapy because extraction may lead to a risk of osteonecrosis. A case report of misdiagnosis related to a tooth with a vertical root fracture in an oncologic patient treated with BPs is reported here. In 2011, a 75-year-old woman was examined at the oral medicine clinic because of pain and swelling of the left submandibular area. The patient's medical history included oral and intravenous BP therapy because she was diagnosed with metastatic breast cancer and left maxillary stage 1 antiresorptive agent-induced osteonecrosis of the jaw. The lower left odontogenic region showed no signs or symptoms, and no apical pathosis was observed on imaging. Although antibiotics were applied, clinical symptoms worsened and an OCST appeared. Intravenous antibiotic treatment was pursued. Biopsy and direct smear from fistula were not conclusive. A diagnosis of a nonexposed variant of stage 3 antiresorptive agent-induced osteonecrosis of the jaw was established. Symptoms resolved after 2 weeks of antibiotic treatment and reappeared a month later. Endodontic examination revealed that the origin of the OCST was tooth no. 18 caused by a vertical root fracture, and the tooth was extracted. The patient was scheduled for routine checkups because of the fact that osteonecrosis may occur in intravenous BP-treated patients. Early correct diagnosis can prevent unnecessary and ineffective antibiotic therapy and surgical intervention, which is not recommended in intravenous BP cases. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Resistance to uprooting of Alfalfa and Avena Sativa and related importance for flume experiments

NASA Astrophysics Data System (ADS)

Edmaier, K.; Crouzy, B.; Burlando, P.; Perona, P.

2012-04-01

Vegetation influences sediment dynamics by stabilizing the alluvial sediment with its root system. Thus, vegetation engineers the riparian ecosystem by contributing to the formation and stabilization of river bars and islands. The resistance to uprooting of young plants in non-cohesive sediment depends on the competition between flow induced drag and root growth timescales. The investigation of flow-sediment-plant interactions in situ is difficult since variables cannot be controlled and material hardly be collected. In order to investigate ecomorphological processes, laboratory experiments are essential and have gained importance in the last decade. To achieve a better understanding of the dependence of resistance to uprooting on the root system (length and structure) we conducted vertical uprooting experiments with Alfalfa and Avena Sativa which are both species that have been used in flume experiments on vegetation-flow interactions (e.g. Tal and Paola, 2010; Perona et al., in press). Seeds were seeded on quartz sand and vertically uprooted with constant velocity whereat the weight force required to uproot a seedling was measured. After uprooting, roots were scanned and analyzed and the correlation of root parameters with the uprooting work was studied. Total root length was found to be the best explanatory variable, in particular the uprooting work increases following a power law with increasing root length. The impact of other root parameters (main root length, root number, tortuosity) on the uprooting work was as well analyzed. Still, not all influencing root parameters could be captured, like the angle between roots or root hair distribution. Environmental conditions like grain size and saturation were also found to have an effect on the uprooting resistance of roots. So, lower saturated sediment results in a higher uprooting work. This work is a first step to better understand the energy regime for vegetation uprooting and its dependence on various biological and hydraulic variables. Future experiments using the same sediment and vegetation species will apply this knowledge to further investigate flow-vegetation-sediment interactions.

Periodontal healing after bonding treatment of vertical root fracture.

PubMed

Sugaya, T; Kawanami, M; Noguchi, H; Kato, H; Masaka, N

2001-08-01

Vertical root fractures lead to advanced periodontal breakdown with deep periodontal pockets and vertical bone defects. The purpose of this study is to evaluate clinically the periodontal healing of root fracture treatment using adhesive resin cement. In 22 patients, 23 teeth with vertical root fractures were treated with 4-META/MMA-TBB resin cement. Eleven fractured roots were bonded through the root canal (group A) and 12 fractured roots were bonded extra-orally and replanted (group B). All teeth were then restored with full cast crowns (n=20) or coping (n=3). Mean probing depth was 6.6 mm at pre-treatment and 4.4 mm 6 months after the treatment in group A, and 7.4 mm and 4.6 mm, respectively, in group B. Bleeding scores were 100% at pre-treatment and 36.4% after 6 months in group A and 91.7% and 8.3%, respectively in group B. Radiographic bone level was 56.8% at pretreatment and 59.1% after 6 months in group A, and 18.8% and 29.2%, respectively, in group B. Two roots of group A and three roots of group B were extracted due to refracture, deterioration of periodontal inflammation, mobility, and luxation. The remaining roots (n=18) presented no discomfort to the patients and there was no deterioration of periodontal conditions over a mean period of 33 months (range 14-74 months) in group A and over a mean period of 22 months (range 6-48 months) in group B. There was no ankylosed teeth nor was any root resorption detected. The results suggested that the treatment of vertical root fracture using 4-META/MMA-TBB resin has good prognostic possibilities.

PHYTOCHROME KINASE SUBSTRATE1 Regulates Root Phototropism and Gravitropism1[C][W][OA

PubMed Central

Boccalandro, Hernán E.; De Simone, Silvia N.; Bergmann-Honsberger, Ariane; Schepens, Isabelle; Fankhauser, Christian; Casal, Jorge J.

2008-01-01

Light promotes the expression of PHYTOCHROME KINASE SUBSTRATE1 (PKS1) in the root of Arabidopsis thaliana, but the function of PKS1 in this organ is unknown. Unilateral blue light induced a negative root phototropic response mediated by phototropin 1 in wild-type seedlings. This response was absent in pks1 mutants. In the wild type, unilateral blue light enhanced PKS1 expression in the subapical region of the root several hours before bending was detectable. The negative phototropism and the enhanced PKS1 expression in response to blue light required phytochrome A (phyA). In addition, the pks1 mutation enhanced the root gravitropic response when vertically oriented seedlings were placed horizontally. The negative regulation of gravitropism by PKS1 occurred even in dark-grown seedlings and did not require phyA. Blue light also failed to induce negative phototropism in pks1 under reduced gravitational stimulation, indicating that the effect of pks1 on phototropism is not simply the consequence of the counteracting effect of enhanced gravitropism. We propose a model where the background level of PKS1 reduces gravitropism. After a phyA-dependent increase in its expression, PKS1 positively affects root phototropism and both effects contribute to negative curvature in response to unilateral blue light. PMID:18024556

PHYTOCHROME KINASE SUBSTRATE1 regulates root phototropism and gravitropism.

PubMed

Boccalandro, Hernán E; De Simone, Silvia N; Bergmann-Honsberger, Ariane; Schepens, Isabelle; Fankhauser, Christian; Casal, Jorge J

2008-01-01

Light promotes the expression of PHYTOCHROME KINASE SUBSTRATE1 (PKS1) in the root of Arabidopsis thaliana, but the function of PKS1 in this organ is unknown. Unilateral blue light induced a negative root phototropic response mediated by phototropin 1 in wild-type seedlings. This response was absent in pks1 mutants. In the wild type, unilateral blue light enhanced PKS1 expression in the subapical region of the root several hours before bending was detectable. The negative phototropism and the enhanced PKS1 expression in response to blue light required phytochrome A (phyA). In addition, the pks1 mutation enhanced the root gravitropic response when vertically oriented seedlings were placed horizontally. The negative regulation of gravitropism by PKS1 occurred even in dark-grown seedlings and did not require phyA. Blue light also failed to induce negative phototropism in pks1 under reduced gravitational stimulation, indicating that the effect of pks1 on phototropism is not simply the consequence of the counteracting effect of enhanced gravitropism. We propose a model where the background level of PKS1 reduces gravitropism. After a phyA-dependent increase in its expression, PKS1 positively affects root phototropism and both effects contribute to negative curvature in response to unilateral blue light.

Theoretical parametric study of the relative advantages of winglets and wing-tip extensions

NASA Technical Reports Server (NTRS)

Heyson, H. H.; Riebe, G. D.; Fulton, C. L.

1977-01-01

It was found that for identical increases in bending moment, a winglet provides a greater gain in induced efficiency than a tip extension. Winglet toe-in angle allows design trades between efficiency and root moment. A winglet showed the greatest benefit when the wing loads were heavy near the tip. Washout diminished the benefit of either tip modification, and the gain in induced efficiency became a function of lift coefficient; heavy wing loadings obtained the greatest benefit from a winglet, and low speed performance was enhanced even more than cruise performance. Both induced efficiency and bending moment increased with winglet length and outward cant. The benefit of a winglet relative to a tip extension was greatest for a nearly vertical winglet. Root bending moment was proportional to the minimum weight of bending material required in the wing; it is a valid index of the impact of tip modifications on a new wing design.

Theoretical Parametric Study of the Relative Advantages of Winglets and Wing-Tip Extensions

NASA Technical Reports Server (NTRS)

Heyson, H. H.; Riebe, G. D.; Fulton, C. L.

1977-01-01

For identical increases in bending moment, a winglet provides a greater gain in induced efficiency than tip extension. Winglet toe angle allows design trades between efficiency and root moment. A winglet shows the greatest benefit when the wing loads are heavy near the tip. Washout diminishes the benefit of either tip modification, and the gain in induced efficiency becomes a function of lift coefficient; thus, heavy wing loadings obtain the greatest benefit from a winglet, and low-speed performance is enhanced even more than cruise performance. Both induced efficiency and bending moment increase with winglet length and outward cant. The benefit of a winglet relative to a tip extension is greatest for a nearly vertical winglet. Root bending moment is proportional to the minimum weight of bending material required in the wing; thus, it is a valid index of the impact of tip modifications on a new wing design.

Patterns of auxin and abscisic acid movement in the tips of gravistimulated primary roots of maize

NASA Technical Reports Server (NTRS)

Young, L. M.; Evans, M. L.

1996-01-01

Because both abscisic acid (ABA) and auxin (IAA) have been suggested as possible chemical mediators of differential growth during root gravitropism, we compared with redistribution of label from applied 3H-IAA and 3H-ABA during maize root gravitropism and examined the relative basipetal movement of 3H-IAA and 3H-ABA applied to the caps of vertical roots. Lateral movement of 3H-ABA across the tips of vertical roots was non-polar and about 2-fold greater than lateral movement of 3H-IAA (also non-polar). The greater movement of ABA was not due to enhanced uptake since the uptake of 3H-IAA was greater than that of 3H-ABA. Basipetal movement of label from 3H-IAA or 3H-ABA applied to the root cap was determined by measuring radioactivity in successive 1 mm sections behind the tip 90 minutes after application. ABA remained largely in the first mm (point of application) whereas IAA was concentrated in the region 2-4 mm from the tip with substantial levels found 7-8 mm from the tip. Pretreatment with inhibitors of polar auxin transport decreased both gravicurvature and the basipetal movement of IAA. When roots were placed horizontally, the movement of 3H-IAA from top to bottom across the cap was enhanced relative to movement from bottom to top whereas the pattern of movement of label from 3H-ABA was unaffected. These results are consistent with the hypothesis that IAA plays a role in root gravitropism but contrary to the idea that gravi-induced asymmetric distribution of ABA contributes to the response.

[Distortion and vertical fracture of the root: effect produced by condenser design].

PubMed

Dang, D A; Walton, R E

1990-01-01

The incidence of vertical root fractures and the amount of root distortion created during lateral condensation of gutta-percha with either D11 spreaders or B-finger pluggers were evaluated in vitro. Fifty-five extracted human, single-rooted teeth were instrumented using the step-back flare technique. Ten teeth served as positive controls (obturation to the point of fracture) and five teeth as negative controls (prepared but not obtured). Strain gauges were attached to the root surfaces. In the experimental group, 20 teeth were obturated using a D11 spreader and 20 with a B-finger plugger. Recordings were made of root distortion (expansion) created during obturation. Then, after sectioning the teeth, root surfaces of obturated samples were examined for fractures under the scanning electron microscope. Only the more tapered spreader, the D11, produces vertical root fractures, although very few in number. Also, the D11 spreader caused greater root distortion than did the B-finger plugger.

Visualization of irrigant flow and cavitation induced by Er:YAG laser within a root canal model.

PubMed

Matsumoto, Himeka; Yoshimine, Yoshito; Akamine, Akifumi

2011-06-01

Laser-activated irrigation (LAI) has recently been introduced as an innovative method for root canal irrigation. However, there is limited information about the cleaning mechanism of an Er:YAG laser. In this study, we visualized the action of laser-induced bubbles and fluid flow in vitro to better understand the physical mechanisms underlying LAI. An Er:YAG laser was equipped with a novel cone-shaped tip with a lateral emission rate of approximately 80%. Laser light was emitted at a pulse energy of 30, 50, or 70 mJ (output energy: 11, 18, or 26 mJ) and a repetition rate of 1 or 20 pulses per second, without air or water spray. Fluid flow dynamics in a root canal model were observed by using glass-bead tracers under a high-speed camera. Moreover, laser-induced bubble patterns were visualized in both free water and the root canal model. Tracers revealed high-speed motion of the fluid. A full cycle of expansion and implosion of vapor and secondary cavitation bubbles were clearly observed. In free water, the vapor bubble expanded for 220 microseconds, and its shape resembled that of an apple. In the root canal model, the vapor bubble expanded in a vertical direction along the canal wall, and bubble expansion continued for ≥700 microseconds. Furthermore, cavitation bubbles were created much more frequently in the canal model than in free water. These results suggest that the cleaning mechanism of an Er:YAG laser within the root canal might depend on rapid fluid motion caused by expansion and implosion of laser-induced bubbles. Copyright © 2011 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Comparison of two vertical condensation obturation techniques: Touch 'n Heat modified and System B.

PubMed

Silver, G K; Love, R M; Purton, D G

1999-08-01

The aims of this study were firstly to compare the area of canal occupied by gutta-percha, sealer or voids using the System B heating device with that obtained by a modified vertical condensation technique using the Touch 'n Heat: and secondly to compare the temperature changes at the root canal wall and external root surface during obturation with the above techniques. Forty-five resin blocks, each with a standardized, simulated, prepared main root canal and five lateral canals, were assigned to three equal experimental groups. The canals were obturated using either the System B technique at two different temperature settings, or vertical condensation with a Touch 'n Heat instrument as the heat source. A heat transfer model was used to simultaneously record internal and external root surface temperature elevations during obturation by the three techniques. Data were analysed using unpaired Student's t-test and Mann-Whitney U-test. Both obturation techniques produced root fillings consisting of over 90% gutta-percha at most levels, although the percentages of sealer and voids 2-3 mm from the working length following System B obturation were higher than those found following modified vertical condensation. Modified vertical condensation resulted in more gutta-percha in lateral canals. Obturation was accomplished more quickly using the System B, and temperature elevations produced during obturation with the System B were significantly less (P < 0.001) than with vertical condensation. An elevation of external root surface temperature by more than 10 degrees C occurred during vertical condensation. The results suggest that the System B may produce an acceptable obturation and that the use of a Touch 'n Heat source during vertical condensation may result in damage to the periodontium.

Waterlogging-induced changes in root architecture of germplasm accessions of the tropical forage grass Brachiaria humidicola.

PubMed

Cardoso, Juan Andrés; Jiménez, Juan de la Cruz; Rao, Idupulapati M

2014-04-08

Waterlogging is one of the major factors limiting the productivity of pastures in the humid tropics. Brachiaria humidicola is a forage grass commonly used in zones prone to temporary waterlogging. Brachiaria humidicola accessions adapt to waterlogging by increasing aerenchyma in nodal roots above constitutive levels to improve oxygenation of root tissues. In some accessions, waterlogging reduces the number of lateral roots developed from main root axes. Waterlogging-induced reduction of lateral roots could be of adaptive value as lateral roots consume oxygen supplied from above ground via their parent root. However, a reduction in lateral root development could also be detrimental by decreasing the surface area for nutrient and water absorption. To examine the impact of waterlogging on lateral root development, an outdoor study was conducted to test differences in vertical root distribution (in terms of dry mass and length) and the proportion of lateral roots to the total root system (sum of nodal and lateral roots) down the soil profile under drained or waterlogged soil conditions. Plant material consisted of 12 B. humidicola accessions from the gene bank of the International Center for Tropical Agriculture, Colombia. Rooting depth was restricted by 21 days of waterlogging and confined to the first 30 cm below the soil surface. Although waterlogging reduced the overall proportion of lateral roots, its proportion significantly increased in the top 10 cm of the soil. This suggests that soil flooding increases lateral root proliferation of B. humidicola in the upper soil layers. This may compensate for the reduction of root surface area brought about by the restriction of root growth at depths below 30 cm. Further work is needed to test the relative efficiency of nodal and lateral roots for nutrient and water uptake under waterlogged soil conditions. Published by Oxford University Press on behalf of the Annals of Botany Company.

Performance of an artificial neural network for vertical root fracture detection: an ex vivo study.

PubMed

Kositbowornchai, Suwadee; Plermkamon, Supattra; Tangkosol, Tawan

2013-04-01

To develop an artificial neural network for vertical root fracture detection. A probabilistic neural network design was used to clarify whether a tooth root was sound or had a vertical root fracture. Two hundred images (50 sound and 150 vertical root fractures) derived from digital radiography--used to train and test the artificial neural network--were divided into three groups according to the number of training and test data sets: 80/120,105/95 and 130/70, respectively. Either training or tested data were evaluated using grey-scale data per line passing through the root. These data were normalized to reduce the grey-scale variance and fed as input data of the neural network. The variance of function in recognition data was calculated between 0 and 1 to select the best performance of neural network. The performance of the neural network was evaluated using a diagnostic test. After testing data under several variances of function, we found the highest sensitivity (98%), specificity (90.5%) and accuracy (95.7%) occurred in Group three, for which the variance of function in recognition data was between 0.025 and 0.005. The neural network designed in this study has sufficient sensitivity, specificity and accuracy to be a model for vertical root fracture detection. © 2012 John Wiley & Sons A/S.

Root gravitropism in response to a signal originating outside of the cap

NASA Technical Reports Server (NTRS)

Wolverton, Chris; Mullen, Jack L.; Ishikawa, Hideo; Evans, Michael L.

2002-01-01

We have developed image analysis software linked to a rotating stage, allowing constraint of any user-selected region of a root at a prescribed angle during root gravitropism. This device allows the cap of a graviresponding root to reach vertical while maintaining a selected region within the elongation zone at a gravistimulated angle. Under these conditions gravitropic curvature of roots of Zea mays L. continues long after the root cap reaches vertical, indicating that a signal from outside of the cap can contribute to the curvature response.

The role of root distribution in eco-hydrological modeling in semi-arid regions

NASA Astrophysics Data System (ADS)

Sivandran, G.; Bras, R. L.

2010-12-01

In semi arid regions, the rooting strategies employed by vegetation can be critical to its survival. Arid regions are characterized by high variability in the arrival of rainfall, and species found in these areas have adapted mechanisms to ensure the capture of this scarce resource. Niche separation, through rooting strategies, is one manner in which different species coexist. At present, land surface models prescribe rooting profiles as a function of only the plant functional type of interest with no consideration for the soil texture or rainfall regime of the region being modeled. These models do not incorporate the ability of vegetation to dynamically alter their rooting strategies in response to transient changes in environmental forcings and therefore tend to underestimate the resilience of many of these ecosystems. A coupled, dynamic vegetation and hydrologic model, tRIBS+VEGGIE, was used to explore the role of vertical root distribution on hydrologic fluxes. Point scale simulations were carried out using two vertical root distribution schemes: (i) Static - a temporally invariant root distribution; and (ii) Dynamic - a temporally variable allocation of assimilated carbon at any depth within the root zone in order to minimize the soil moisture-induced stress on the vegetation. The simulations were forced with a stochastic climate generator calibrated to weather stations and rain gauges in the semi-arid Walnut Gulch Experimental Watershed in Arizona. For the static root distribution scheme, a series of simulations were carried out varying the shape of the rooting profile. The optimal distribution for the simulation was defined as the root distribution with the maximum mean transpiration over a 200 year period. This optimal distribution was determined for 5 soil textures and using 2 plant functional types, and the results varied from case to case. The dynamic rooting simulations allow vegetation the freedom to adjust the allocation of assimilated carbon to different rooting depths in response to changes in stress caused by the redistribution and uptake of soil moisture. The results obtained from these experiments elucidate the strong link between plant functional type, soil texture and climate and highlight the potential errors in the modeling of hydrologic fluxes from imposing a static root profile.

Autonomic straightening after gravitropic curvature of cress roots

NASA Technical Reports Server (NTRS)

Stankovic, B.; Volkmann, D.; Sack, F. D.

1998-01-01

Few studies have documented the response of gravitropically curved organs to a withdrawal of a constant gravitational stimulus. The effects of stimulus withdrawal on gravitropic curvature were studied by following individual roots of cress (Lepidium sativum L.) through reorientation and clinostat rotation. Roots turned to the horizontal curved down 62 degrees and 88 degrees after 1 and 5 h, respectively. Subsequent rotation on a clinostat for 6 h resulted in root straightening through a loss of gravitropic curvature in older regions and through new growth becoming aligned closer to the prestimulus vertical. However, these roots did not return completely to the prestimulus vertical, indicating the retention of some gravitropic response. Clinostat rotation shifted the mean root angle -36 degrees closer to the prestimulus vertical, regardless of the duration of prior horizontal stimulation. Control roots (no horizontal stimulation) were slanted at various angles after clinostat rotation. These findings indicate that gravitropic curvature is not necessarily permanent, and that the root retains some commitment to its equilibrium orientation prior to gravitropic stimulation.

Intracellular magnetophoresis of amyloplasts and induction of root curvature

NASA Technical Reports Server (NTRS)

Kuznetsov, O. A.; Hasenstein, K. H.

1996-01-01

High-gradient magnetic fields (HGMFs) were used to induce intracellular magnetophoresis of amyloplasts. The HGMFs were generated by placing a small ferromagnetic wedge into a uniform magnetic field or at the gap edge between two permanent magnets. In the vicinity of the tip of the wedge the dynamic factor of the magnetic field, delta(H2/2), was about 10(9) Oe2.cm-1, which subjected the amyloplasts to a force comparable to that of gravity. When roots of 2-d-old seedlings of flax (Linum usitatissimum L.) were positioned vertically and exposed to an HGMF, curvature away from the wedge was transient and lasted approximately 1 h. Average curvature obtained after placing magnets, wedge and seedlings on a 1-rpm clinostat for 2 h was 33 +/- 5 degrees. Roots of horizontally placed control seedlings without rotation curved about 47 +/- 4 degrees. The time course of curvature and changes in growth rate were similar for gravicurvature and for root curvature induced by HGMFs. Microscopy showed displacement of amyloplasts in vitro and in vivo. Studies with Arabidopsis thaliana (L.) Heynh. showed that the wild type responded to HGMFs but the starchless mutant TC7 did not. The data indicate that a magnetic force can be used to study the gravisensing and response system of roots.

Novel software for analysis of root gravitropism: comparative response patterns of Arabidopsis wild-type and axr1 seedlings

NASA Technical Reports Server (NTRS)

Ishikawa, H.; Evans, M. L.

1997-01-01

In an earlier study (Evans, Ishikawa & Estelle 1994, Planta 194, 215-222) we used a video digitizer system to compare the kinetics of auxin action on root elongation in wild-type seedlings and seedlings of auxin response mutants of Arabidopsis thaliana (L.) Heynh. We have since modified the system software to allow determination of elongation on opposite sides of vertical or gravistimulated roots and to allow continuous measurement of the angle of orientation of sequential subsections of the root during the response. We used this technology to compare the patterns of differential growth that generate curvature in roots of the Columbia ecotype and in the mutants axr1-3, axr1-12 and axr2, which show reduced gravitropic responsiveness and reduced sensitivity to inhibition by auxin. The pattern of differential growth during gravitropism differed in roots of wild-type and axr1 seedlings. In wild-type roots, initial curvature resulted from differential inhibition of elongation in the distal elongation zone (DEZ). This was followed by an acceleration of elongation along the top side of the DEZ. In roots of axr1-3, curvature resulted from differential stimulation of elongation whereas in roots of axr1-12 the response was variable. Roots of axr2 did not exhibit gravitropic curvature. The observation that the pattern of differential growth causing curvature is dramatically altered by a change in sensitivity to auxin is consistent with the classical Cholodny-Went theory of gravitropism which maintains that differential growth patterns induced by gravistimulation are mediated primarily by gravi-induced shifts in auxin distribution. The new technology introduced with this report allows automated determination of stimulus response patterns in the small but experimentally popular roots of Arabidopsis.

The persistence of the gravity signal in flax roots

NASA Astrophysics Data System (ADS)

Hasenstein, Karl H.

Although the presentation time of gravitropism has been studied, no data exist as to how long a reorientation stimulus affects the gravitropic response of a root. We tested the duration of gravitropic curvature in roots of Linum usitatissimum after reversing a one hour, 90 degree gravistimulus by increasing time intervals in vertical orientation before clinorotating the roots and acquiring infrared digital images. Clinorotation was performed either parallel or perpendicular to the gravity vector. Under either condition the gravistimulus affected curvature during clinorotation only between two to three minutes. Maximal curvature after one minute of vertical reorientation was 15 degrees within one hour. After three minutes in vertical orientation the observed curvature was not statistically different from vertically growing roots. In both orientations, maximum curvature occurred after 1hr. Perpendicular (horizontal) clinorotation showed decreasing curvature with increasing reorientation time. Parallel (vertical) clinorotation resulted in greater variability to the reorientation time. These data indicate that the gravity stimulus operates essentially memory free and that clinorotation affects the gravity response. Therefore all aspects of clinorotation need to be studied before an assessment of clinostats for the simulation of microgravity is possible and a time limit for memory effects of mechanostimulation can be determined.

Cytochemical localization of calcium in cap cells of primary roots of Zea mays L

NASA Technical Reports Server (NTRS)

Moore, R.

1986-01-01

The distribution of calcium (Ca) in caps of vertically- and horizontally-oriented roots of Zea mays was monitored to determine its possible role in root graviresponsiveness. A modification of the antimonate precipitation procedure was used to localize Ca in situ. In vertically-oriented roots, the presumed graviperceptive (i.e., columella) cells were characterized by minimal and symmetric staining of the plasmalemma and mitochondria. No precipitate was present in plasmodesmata or cell walls. Within 5 min after horizontal reorientation, staining was associated with the portion of the cell wall adjacent to the distal end of the cell. This asymmetric staining persisted throughout the onset of gravicurvature. No staining of lateral cell walls of columella cells was observed at any stage of gravicurvature, suggesting that a lateral flow of Ca through the columella tissue of horizontally-oriented roots does not occur. The outermost peripheral cells of roots oriented horizontally and vertically secrete Ca through plasmodesmata-like structures in their cell walls. These results are discussed relative to proposed roles of root-cap Ca in root gravicurvature.

Low phosphate alters lateral root setpoint angle and gravitropism.

PubMed

Bai, Hanwen; Murali, Bhavna; Barber, Kevin; Wolverton, Chris

2013-01-01

Lateral roots, responsible for water and nutrient uptake, maintain nonvertical angles throughout development. Soil phosphate is one limiting nutrient for plant growth that is known to induce changes to root system architecture, such as increased lateral root formation. This study seeks to determine whether phosphate concentration affects lateral root orientation in addition to its previously described influences on root architecture. Images of intact Arabidopsis root systems were recorded for 24 h, and lateral root tip angles were measured for wild-type and mutant pgm-1 and pin3-1 roots on a full or low phosphate medium. Setpoint angles of unstimulated root systems were determined, as were gravitropic responses of lateral roots over time. The root system setpoint angles of wild-type and mutant pin3-1 roots showed a shift toward a more vertical orientation on low orthophosphate (Pi) medium. The gravitropic responses of both pgm-1 and pin3-1 roots on low Pi medium was elevated relative to control Pi medium. Mutations in two phosphate transporters with high levels of expression in the root showed a gravitropic response similar to wild-type roots grown on low Pi, supporting a role for Pi status in regulating lateral root gravitropism. Lateral root orientation and gravitropism are affected by Pi status and may provide an important additional parameter for describing root responses to low Pi. The data also support the conclusion that gravitropic setpoint angle reacts to nutrient status and is under dynamic regulation.

Polar transport of 45Ca2+ across the elongation zone of gravistimulated roots

NASA Technical Reports Server (NTRS)

Lee, J. S.; Evans, M. L.

1985-01-01

The movement of calcium across the elongation zone of gravistimulated primary roots of maize (Zea mays L.) was measured using 45Ca2+. Radioactive calcium was applied to one side of the elongation zone about 4 mm back from the root tip and the distribution of radioactivity across the root in the region of application was determined using scintillation spectrometry. The movement of 45Ca2+ across the elongation zone was non-polar in vertically oriented roots. In gravistimulated roots the movement of label was polarized with about twice as much label moving from top to bottom as from bottom to top. A variety of treatments which interfere with gravitropism was found to eliminate the polar movement of 45Ca2+ across the elongation zone. In maize cultivars which require light for gravitropic competency, dark grown roots exhibited neither gravitropism nor polar movement of 45Ca2+ across the elongation zone. Upon illumination the roots developed but gravitropic competency and gravity-induced polar movement of 45Ca2+ across the elongation zone. Similarly, roots of light-grown seedlings lost both gravitropic competency and 45Ca2+ transport polarity upon transfer to the dark. The results indicate a close correlation between calcium movement and gravitropism in primary roots in maize.

Effect of piezocision on root resorption associated with orthodontic force: A microcomputed tomography study.

PubMed

Patterson, Braydon M; Dalci, Oyku; Papadopoulou, Alexandra K; Madukuri, Suman; Mahon, Jonathan; Petocz, Peter; Spahr, Axel; Darendeliler, M Ali

2017-01-01

The purpose of this study was to investigate the effect of piezocision on orthodontically induced inflammatory root resorption. Fourteen patients were included in this split-mouth study; 1 side was assigned to piezocision, and the other side served as the control. Vertical corticotomy cuts of 4 to 5 mm in length were performed on either side of each piezocision premolar, and 150-g buccal tipping forces were applied to the premolars. After 4 weeks, the maxillary first premolars were extracted and scanned with microcomputed tomography. There was a significantly greater total amount of root resorption seen on the piezocision sides when compared with the control sides (P = 0.029). The piezocision procedure resulted in a 44% average increase in root resorption. In 5 patients, there was noticeable piezocision-related iatrogenic root damage. When that was combined with the orthodontic root resorption found on the piezocision-treated teeth, there was a statistically significant 110% average increase in volumetric root loss when compared with the control side (P = 0.005). The piezocision procedure that initiates the regional acceleratory phenomenon may increase the iatrogenic root resorption when used in conjunction with orthodontic forces. Piezocision applied close to the roots may cause iatrogenic damage to the neighboring roots and should be used carefully. Copyright © 2017.

Diagnosis and Managment of Maxillary Incisor with Vertical Root Fracture: A Clinical Report with Three-Year Follow-Up

PubMed Central

Moussaoui, Eya; Chtioui, Fadwa; Douki, Nabiha

2018-01-01

According to the American Association of Endodontists, “a ‘true' vertical root fracture is defined as a complete or incomplete fracture initiated from the root at any level, usually directed buccolingually.” Vertical root fracture (VRF) usually starts from an internal dentinal crack and develops over time, due to masticatory forces and occlusal loads. When they occur in teeth, those types of fractures can present difficulties in diagnosis, and there are however many clinic and radiographical signs which can guide clinicians to the existence of the fracture. Prognosis, most often, is hopeless, and differential diagnosis from other etiologies may be difficult sometimes. In this paper, we present a case of VRF diagnosed after surgical exploration; the enlarged fracture line was filled with a fluid resin. A 36-month clinical and radiological follow-up showed an asymptomatic tooth, reduction of the periodontal probing depth from 7 mm prior to treatment to 4 mm with no signs of ankylosis. In this work, the diagnosis and treatment alternatives of vertical root fracture were discussed through the presented clinical case. PMID:29552361

Diagnosis and Managment of Maxillary Incisor with Vertical Root Fracture: A Clinical Report with Three-Year Follow-Up.

PubMed

Kallel, Ines; Moussaoui, Eya; Chtioui, Fadwa; Douki, Nabiha

2018-01-01

According to the American Association of Endodontists, "a 'true' vertical root fracture is defined as a complete or incomplete fracture initiated from the root at any level, usually directed buccolingually." Vertical root fracture (VRF) usually starts from an internal dentinal crack and develops over time, due to masticatory forces and occlusal loads. When they occur in teeth, those types of fractures can present difficulties in diagnosis, and there are however many clinic and radiographical signs which can guide clinicians to the existence of the fracture. Prognosis, most often, is hopeless, and differential diagnosis from other etiologies may be difficult sometimes. In this paper, we present a case of VRF diagnosed after surgical exploration; the enlarged fracture line was filled with a fluid resin. A 36-month clinical and radiological follow-up showed an asymptomatic tooth, reduction of the periodontal probing depth from 7 mm prior to treatment to 4 mm with no signs of ankylosis. In this work, the diagnosis and treatment alternatives of vertical root fracture were discussed through the presented clinical case.

Presence of Trifolium repens Promotes Complementarity of Water Use and N Facilitation in Diverse Grass Mixtures.

PubMed

Hernandez, Pauline; Picon-Cochard, Catherine

2016-01-01

Legume species promote productivity and increase the digestibility of herbage in grasslands. Considerable experimental data also indicate that communities with legumes produce more above-ground biomass than is expected from monocultures. While it has been attributed to N facilitation, evidence to identify the mechanisms involved is still lacking and the role of complementarity in soil water acquisition by vertical root differentiation remains unclear. We used a 20-months mesocosm experiment to investigate the effects of species richness (single species, two- and five-species mixtures) and functional diversity (presence of the legume Trifolium repens) on a set of traits related to light, N and water use and measured at community level. We found a positive effect of Trifolium presence and abundance on biomass production and complementarity effects in the two-species mixtures from the second year. In addition the community traits related to water and N acquisition and use (leaf area, N, water-use efficiency, and deep root growth) were higher in the presence of Trifolium. With a multiple regression approach, we showed that the traits related to water acquisition and use were with N the main determinants of biomass production and complementarity effects in diverse mixtures. At shallow soil layers, lower root mass of Trifolium and higher soil moisture should increase soil water availability for the associated grass species. Conversely at deep soil layer, higher root growth and lower soil moisture mirror soil resource use increase of mixtures. Altogether, these results highlight N facilitation but almost soil vertical differentiation and thus complementarity for water acquisition and use in mixtures with Trifolium. Contrary to grass-Trifolium mixtures, no significant over-yielding was measured for grass mixtures even those having complementary traits (short and shallow vs. tall and deep). Thus, vertical complementarity for soil resources uptake in mixtures was not only dependant on the inherent root system architecture but also on root plasticity. We also observed a time-dependence for positive complementarity effects due to the slow development of Trifolium in mixtures, possibly induced by competition with grasses. Overall, our data underlined that soil water resource was an important driver of over-yielding and complementarity effects in Trifolium-grass mixtures.

Vertical force and torque analysis during mechanical preparation of extracted teeth using hand ProTaper instruments.

PubMed

Glavičić, Snježana; Anić, Ivica; Braut, Alen; Miletić, Ivana; Borčić, Josipa

2011-08-01

The purpose was to measure and analyse the vertical force and torque developed in the wider and narrower root canals during hand ProTaper instrumentation. Twenty human incisors were divided in two groups. Upper incisors were experimental model for the wide, while the lower incisors for the narrow root canals. Measurements of the force and torque were done by a device constructed for this purpose. Differences between the groups were statistically analysed by Mann-Whitney U-test with the significance level set to P<0.05. Vertical force in the upper incisors ranged 0.25-2.58 N, while in the lower incisors 0.38-6.94 N. Measured torque in the upper incisors ranged 0.53-12.03 Nmm, while in the lower incisor ranged 0.94-10.0 Nmm. Vertical force and torque were higher in the root canals of smaller diameter. The increase in the contact surface results in increase of the vertical force and torque as well in both narrower and wider root canals. © 2010 The Authors. Australian Endodontic Journal © 2010 Australian Society of Endodontology.

Interference of allelopathic rice with paddy weeds at the root level.

PubMed

Yang, X-F; Kong, C-H

2017-07-01

Despite increasing knowledge of the involvement of allelopathy in negative interactions among plants, relatively little is known about its action at the root level. This study aims to enhance understanding of interactions of roots between a crop and associated weeds via allelopathy. Based on a series of experiments with window rhizoboxes and root segregation methods, we examined root placement patterns and root interactions between allelopathic rice and major paddy weeds Cyperus difformis, Echinochloa crus-galli, Eclipta prostrata, Leptochloa chinensis and Oryza sativa (weedy rice). Allelopathic rice inhibited growth of paddy weed roots more than shoots regardless of species. Furthermore, allelopathic rice significantly reduced total root length, total root area, maximum root width and maximum root depth of paddy weeds, while the weeds adjusted horizontal and vertical placement of their roots in response to the presence of allelopathic rice. With the exception of O. sativa (weedy rice), root growth of weeds avoided expanding towards allelopathic rice. Compared with root contact, root segregation significantly increased inhibition of E. crus-galli, E. prostrata and L. chinensis through an increase in rice allelochemicals. In particular, their root exudates induced production of rice allelochemicals. However, similar results were not observed in C. difformis and O. sativa (weedy rice) with either root segregation or root exudate application. The results demonstrate that allelopathic rice interferes with paddy weeds by altering root placement patterns and root interactions. This is the first case of a root behavioural strategy in crop-weed allelopathic interaction. © 2017 German Botanical Society and The Royal Botanical Society of the Netherlands.

Stemflow-induced processes of soil water storage

NASA Astrophysics Data System (ADS)

Germer, Sonja

2013-04-01

Compared to stemflow production studies only few studies deal with the fate of stemflow at the near-stem soil. To investigate stemflow contribution to the root zone soil moisture by young and adult babassu palms (Attalea speciosa Mart.), I studied stemflow generation, subsequent soil water percolation and root distributions. Rainfall, stemflow and perched water tables were monitored on an event basis. Perched water tables were monitored next to adult palms at two depths and three stem distances. Dye tracer experiments monitored stemflow-induced preferential flow paths. Root distributions of fine and coarse roots were related to soil water redistribution. Average rainfall-collecting area per adult palm was 6.4 m², but variability between them was high. Funneling ratios ranged between 16-71 and 4-55 for adult and young palms, respectively. Nonetheless, even very small rainfall events of 1 mm can generate stemflow. On average, 9 liters of adult palm stemflow were intercepted and stemflow tended to decrease for-high intensity rainfall events. Young babassu palms funneled rainfall via their fronds, directly to their subterranean stems. The funneling of rainfall towards adult palm stems, in contrast, led to great stemflow fluxes down to the soil and induced initial horizontal water flows through the soil, leading to perched water tables next to palms, even after small rainfall events. The perched water tables extended, however, only a few decimeters from palm stems. After perched water tables became established, vertical percolation through the soil dominated. To my knowledge, this process has not been described before, and it can be seen as an addition to the two previously described stemflow-induced processes of Horton overland flow and fast, deep percolation along roots. This study has demonstrated that Babassu palms funnel water to their stems and subsequently store it in the soil next to their stems in areas where coarse root length density is very high. This might partly explain the competitive position of babassu palms on pastures or secondary forests.

Computer-based video digitizer analysis of surface extension in maize roots: kinetics of growth rate changes during gravitropism

NASA Technical Reports Server (NTRS)

Ishikawa, H.; Hasenstein, K. H.; Evans, M. L.

1991-01-01

We used a video digitizer system to measure surface extension and curvature in gravistimulated primary roots of maize (Zea mays L.). Downward curvature began about 25 +/- 7 min after gravistimulation and resulted from a combination of enhanced growth along the upper surface and reduced growth along the lower surface relative to growth in vertically oriented controls. The roots curved at a rate of 1.4 +/- 0.5 degrees min-1 but the pattern of curvature varied somewhat. In about 35% of the samples the roots curved steadily downward and the rate of curvature slowed as the root neared 90 degrees. A final angle of about 90 degrees was reached 110 +/- 35 min after the start of gravistimulation. In about 65% of the samples there was a period of backward curvature (partial reversal of curvature) during the response. In some cases (about 15% of those showing a period of reverse bending) this period of backward curvature occurred before the root reached 90 degrees. Following transient backward curvature, downward curvature resumed and the root approached a final angle of about 90 degrees. In about 65% of the roots showing a period of reverse curvature, the roots curved steadily past the vertical, reaching maximum curvature about 205 +/- 65 min after gravistimulation. The direction of curvature then reversed back toward the vertical. After one or two oscillations about the vertical the roots obtained a vertical orientation and the distribution of growth within the root tip became the same as that prior to gravistimulation. The period of transient backward curvature coincided with and was evidently caused by enhancement of growth along the concave and inhibition of growth along the convex side of the curve, a pattern opposite to that prevailing in the earlier stages of downward curvature. There were periods during the gravitropic response when the normally unimodal growth-rate distribution within the elongation zone became bimodal with two peaks of rapid elongation separated by a region of reduced elongation rate. This occurred at different times on the convex and concave sides of the graviresponding root. During the period of steady downward curvature the elongation zone along the convex side extended farther toward the tip than in the vertical control. During the period of reduced rate of curvature, the zone of elongation extended farther toward the tip along the concave side of the root. The data show that the gravitropic response pattern varies with time and involves changes in localized elongation rates as well as changes in the length and position of the elongation zone. Models of root gravitropic curvature based on simple unimodal inhibition of growth along the lower side cannot account for these complex growth patterns.

Pathways of soil moisture controls on boundary layer dynamics

NASA Astrophysics Data System (ADS)

Siqueira, M.; Katul, G.; Porporato, A.

2007-12-01

Soil moisture controls on precipitation are now receiving significant attention in climate systems because the memory of their variability is much slower than the memory of the fast atmospheric processes. We propose a new model that integrates soil water dynamics, plant hydraulics and stomatal responses to water availability to estimate root water uptake and available energy partitioning, as well as feedbacks to boundary layer dynamics (in terms of water vapor and heat input to the atmospheric system). Using a simplified homogenization technique, the model solves the intrinsically 3-D soil water movement equations by two 1-D coupled Richards' equations. The first resolves the radial water flow from bulk soil to soil-root interface to estimate root uptake (assuming the vertical gradients in moisture persist during the rapid lateral flow), and then it solves vertical water movement through the soil following the radial moisture adjustments. The coupling between these two equations is obtained by area averaging the soil moisture in the radial domain (i.e. homogenization) to calculate the vertical fluxes. For each vertical layer, the domain is discretized in axi-symmetrical grid with constant soil properties. This is deemed to be appropriate given the fact that the root uptake occurs on much shorter time scales closely following diurnal cycles, while the vertical water movement is more relevant to the inter-storm time scale. We show that this approach was able to explicitly simulate known features of root uptake such as diurnal hysteresis of canopy conductance, water redistribution by roots (hydraulic lift) and downward shift of root uptake during drying cycles. The model is then coupled with an atmospheric boundary layer (ABL) growth model thereby permitting us to explore low-dimensional elements of the interaction between soil moisture and ABL states commensurate with the lifting condensation level.

Distribution of electrolytes in cells of the tomato root elongation zone during a gravitropic response

NASA Astrophysics Data System (ADS)

Klymchuk, Dmytro

It is known that gravitropic response of etiolated seedlings is accompanied with asymmetrical distribution of auxins. The higher amount of auxins in the tissues of the lower sides of gravistimulated organs induces cell elongation in shoots and inhibits cell elongation in roots. In spite on the progress in understanding of the auxin-mediated effects on plant growth and development, there is no a complete conception concerning of gravitropic response mechanism. This investigation aims to determine whether the growth response of tomato seedlings on reorientation to the horizontal induces alterations in distribution of electrolytes in cells of the main root elongation zone, the site where induction of the curvature takes place. Tomato (Lycopersicon esculentum, Rio Grande) seedlings were grown on agar surface in 10 cm Petri dishes. The gravitropic response of seedlings was evaluated by the angle of gravitropic curvature after the roots were reoriented 90° from the vertical. Root segments of several mm basipetal to the root tip were fixed in liquid nitrogen, freeze-substituted with Lowicril K11M at -35° C. Sections 100 and 1000 nm thick were cut using LKB Ultrotome V, collected by dry method and analyzed in the 6060 LA SEM at accelerating voltage 15 kV. Using different modes of X-ray microanalysis (X-ray map, - line and -point analysis), distribution of the physiologically relevant ions (Na, P, K, Ca) in cells of surface layers of the upper and lower root sides were investigated. The peculiarities in localization of the electrolytes in different subcellular compartments as well as distribution in the direction between upper and lower sides of the root curvature are discussed.

Comparative evaluation of the vertical fracture resistance of endodontically treated roots filled with Gutta-percha and Resilon: a meta-analysis of in vitro studies.

PubMed

Tan, Minmin; Chai, Zhaowu; Sun, Chengjun; Hu, Bo; Gao, Xiang; Chen, Yunjia; Song, Jinlin

2018-06-13

Teeth treated endodontically are more susceptible to vertical root fracture (VRF). Some studies have suggested that obturating the root canals with Gutta-percha or Resilon can reinforce endodontically treated teeth, but a few others have presented conflicting results. These inconsistent results cannot guide clinicians in determining clinical approaches. The objective of this meta-analysis is to evaluate and compare the vertical fracture resistance of endodontically treated root canals obturated with Gutta-percha/AH plus and the Resilon system. Comprehensive literature searches were performed in the PubMed, Cochrane Library, ScienceDirect, Web of Science and Embase databases. The titles and abstracts of all of the retrieved articles were independently assessed by two authors according to predefined selection criteria. Data in the included articles were independently extracted. Statistical analyses were conducted using Review Manager 5.3 and Stata 12.0 software. The pooled standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated for the outcome indicators. The level of statistical significance was set at p < 0.05. The Cochran Q test (I 2 test) was used to test for heterogeneity among studies. Fourteen randomized controlled in vitro trials were included in the meta-analysis. The results demonstrated that the vertical root fracture resistance of unprepared and unfilled roots was significantly higher than that of roots obturated with Gutta-percha/AH plus (SMD = - 0.69, 95% CI = - 1.34 to - 0.04, p = 0.04) or the Resilon system (SMD = - 0.54, 95% CI = - 1.07 to - 0.00, p = 0.05). The differences in fracture resistance between the roots filled with Gutta-percha/AH plus and the prepared unfilled root canals was not significant (SMD = 0.59, 95% CI = - 0.02 to 1.21, p = 0.06). Roots obturated with Resilon had higher fracture resistance than instrumented unfilled roots (SMD = 0.83, 95% CI = 0.44 to 1.22, p < 0.0001) or roots filled with Gutta-percha/AH plus (SMD = 0.62, 95% CI = 0.01 to 1.23, p = 0.05). The present study suggests that filling with Gutta-percha/AH plus dose not reinforce endodontically treated roots, whereas obturating with the Resilon system can increase vertical root fracture resistance of prepared roots. As this meta-analysis was based on in vitro studies, it should be careful to extrapolate its conclusion to the clinical context.

Fine root responses to temporal nutrient heterogeneity and competition in seedlings of two tree species with different rooting strategies.

PubMed

Wang, Peng; Shu, Meng; Mou, Pu; Weiner, Jacob

2018-03-01

There is little direct evidence for effects of soil heterogeneity and root plasticity on the competitive interactions among plants. In this study, we experimentally examined the impacts of temporal nutrient heterogeneity on root growth and interactions between two plant species with very different rooting strategies: Liquidambar styraciflua (sweet gum), which shows high root plasticity in response to soil nutrient heterogeneity, and Pinus taeda (loblolly pine), a species with less plastic roots. Seedlings of the two species were grown in sandboxes in inter- and intraspecific combinations. Nutrients were applied in a patch either in a stable (slow-release) or in a variable (pulse) manner. Plant aboveground biomass, fine root mass, root allocation between nutrient patch and outside the patch, and root vertical distribution were measured. L. styraciflua grew more aboveground (40% and 27% in stable and variable nutrient treatment, respectively) and fine roots (41% and 8% in stable and variable nutrient treatment, respectively) when competing with P. taeda than when competing with a conspecific individual, but the growth of P. taeda was not changed by competition from L. styraciflua . Temporal variation in patch nutrient level had little effect on the species' competitive interactions. The more flexible L. styraciflua changed its vertical distribution of fine roots in response to competition from P. taeda , growing more roots in deeper soil layers compared to its roots in conspecific competition, leading to niche differentiation between the species, while the fine root distribution of P. taeda remained unchanged across all treatments. Synthesis . L. styraciflua showed greater flexibility in root growth by changing its root vertical distribution and occupying space of not occupied by P. taeda . This flexibility gave L. styraciflua an advantage in interspecific competition.

Apical stress distribution under vertical compaction of gutta-percha and occlusal loads in canals with varying apical sizes: a three-dimensional finite element analysis.

PubMed

Yuan, K; Niu, C; Xie, Q; Jiang, W; Gao, L; Ma, R; Huang, Z

2018-02-01

To investigate and compare the effects of two apical canal instrumentation protocols on apical stress distribution at the root apex under vertical compaction of gutta-percha and occlusal loads using finite element analysis. Three finite element analysis models of a mandibular first premolar were reconstructed: an original canal model, a size 35, .04 taper apical canal enlargement model and a Lightspeed size 60 apical canal enlargement model. A 15 N compaction force was applied vertically to the gutta-percha 5 mm from the apex. A 175 N occlusal load in two directions (vertical and 45° to the longitudinal axis of the tooth) was simulated. Stresses in the apical 2 mm of the root were calculated and compared among the three models. Under vertical compaction, stresses in the apical canal instrumented by Lightspeed size 60 (maximal 3.3 MPa) were higher than that of the size 35, .04 taper model (maximal 1.3 MPa). In the case of the two occlusal forces, the Lightspeed size 60 apical enlargement was associated with the greatest stress distribution in the apical region. The greatest stress and the most obvious stress difference between the models appeared at the tip of the root when occlusal and vertical compaction loads were applied. Apical enlargement caused stress distribution changes in the apical region of roots. The larger apical size led to higher stress concentration at the root apex. © 2017 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Investigation of the effect of sealer use on the heat generated at the external root surface during root canal obturation using warm vertical compaction technique with System B heat source.

PubMed

Viapiana, Raqueli; Guerreiro-Tanomaru, Juliane Maria; Tanomaru-Filho, Mario; Camilleri, Josette

2014-04-01

During warm vertical compaction of gutta-percha, root canal sealers with different chemical compositions absorb the heat generated inside the root canal. The aim of this research was to assess physicochemical modifications of sealers subjected to the System B heat source (Analytic Technology, Redmond, WA) and to evaluate the effect that the use of different sealers has on the heat transfer to the external root surface. Three proprietary brand sealers (AH Plus [Dentsply International, Addlestone, UK], Pulp Canal Sealer [Kerr Corporation, Orange, CA], MTA Fillapex [Angelus Dental Solutions, Londrina, PR, Brazil]) and a prototype sealer based on Portland cement were assessed. The heat generated on the surfaces of System pluggers and the heat dissipation at different levels (apical, midroot, and cervical) over root surface while using different sealers was assessed using thermocouples. Data were collected in 3 different environmental conditions with the tooth suspended in air, immersed in Hank's balanced salt solution, or gelatinized Hank's balanced salt solution. Chemical changes in the sealers induced by the heat were monitored by Fourier transform infrared spectroscopy. The effect of heat changes on the setting time and compressive strength of the sealers was also assessed. The continuous wave plugger sustained a rise in temperature at a maximum of 80°C at the instrument shank. The highest change in temperature on the external root surface was recorded after 1.5 minutes from the start of heating, and it was restored to body temperature by 6 minutes. Environmental conditions affected heat dissipation for all the sealers in the midroot and cervical regions and the highest increase in temperature (∼60°C) recorded in air. In the midroot and cervical regions, the type of sealer used did not affect the rise in temperature. In the apical region, AH Plus obturations resulted in a greater rise in temperature, and the chemical composition of this sealer was affected by high temperature; it also induced a reduction in sealer setting time and strength. It could be concluded that surrounding conditions, such as temperature and humidity, exerted influence on heating dissipation during the continuous wave of the condensation obturation technique and that root canal sealers presented different conductive/isolating properties. Furthermore, the physical and chemical properties of AH Plus were negatively affected by the changes in temperature. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Effects of mechanostimulation on gravitropism and signal persistence in flax roots.

PubMed

John, Susan P; Hasenstein, Karl H

2011-09-01

Gravitropism describes curvature of plants in response to gravity or differential acceleration and clinorotation is commonly used to compensate unilateral effect of gravity. We report on experiments that examine the persistence of the gravity signal and separate mechanostimulation from gravistimulation. Flax roots were reoriented (placed horizontally for 5, 10 or 15 min) and clinorotated at a rate of 0.5 to 5 rpm either vertically (parallel to the gravity vector and root axis) or horizontally (perpendicular to the gravity vector and parallel to the root axis). Image sequences showed that horizontal clinorotation did not affect root growth rate (0.81 ± 0.03 mm h-1) but vertical clinorotation reduced root growth by about 7%. The angular velocity (speed of clinorotation) did not affect growth for either direction. However, maximal curvature for vertical clinorotation decreased with increasing rate of rotation and produced straight roots at 5 rpm. In contrast, horizontal clinorotation increased curvature with increasing angular velocity. The point of maximal curvature was used to determine the longevity (memory) of the gravity signal, which lasted about 120 min. The data indicate that mechanostimulation modifies the magnitude of the graviresponse but does not affect memory persistence.

Ice-load induced tectonics controlled tunnel valley evolution - instances from the southwestern Baltic Sea

NASA Astrophysics Data System (ADS)

Al Hseinat, M.; Hübscher, C.

2014-08-01

Advancing ice sheets have a strong impact on the earth's topography. For example, they leave behind an erosional unconformity, bulldozer the underlying strata and form tunnel valleys, primarily by subglacial melt-water erosion and secondarily by direct glacial erosion. The conceptual models of the reactivation of faults within the upper crust, due to the ice sheets' load, are also established. However, this phenomenon is also rather under-explored. Here, we propose a causal link between ice-load induced tectonics, the generation of near-vertical faults in the upper crust above an inherited deep-rooted fault and the evolution of tunnel valleys. The Kossau tunnel valley in the southeastern Bay of Kiel has been surveyed by means of high-resolution multi-channel seismic and echosounder data. It strikes almost south to north and can be mapped over a distance of ca 50 km. It is 1200-8000 m wide with a valley of up to 200 m deep. Quaternary deposits fill the valley and cover the adjacent glaciogenic unconformity. A near-vertical fault system with an apparent dip angle of >80°, which reaches from the top Zechstein upwards into the Quaternary, underlies the valley. The fault partially pierces the seafloor and growth is observed within the uppermost Quaternary strata only. Consequently, the fault evolved in the Late Quaternary. The fault is associated with an anticline that is between 700 and 3000 m wide and about 20-40 m high. The fault-anticline assemblage neither resembles any typical extensional, compressional or strike-slip deformation pattern, nor is it related to salt tectonics. Based on the observed position and deformation pattern of the fault-anticline assemblage, we suggest that these structures formed as a consequence of the differential ice-load induced tectonics above an inherited deep-rooted sub-salt fault related to the Glückstadt Graben. Lateral variations in the ice-load during the ice sheet's advance caused differential subsidence, thus rejuvenating the deep-rooted fault. As a result, the inherited fault propagated upwards across the Zechstein and post-Permian overburden and further grew during the ice sheet's retreat. The developing fault and anticline system under the ice sheet created a weakness zone that facilitated erosion by pressurized glacial and subglacial melt-water, as well as by the glaciers themselves. Near-vertical faults cutting through the post-Permian are abundant in the southwestern Baltic realm, which implies that the ice-load induced tectonic activity described above was not an isolated incident.

Gravity response mechanisms of lateral organs and the control of plant architecture in Arabidopsis

NASA Astrophysics Data System (ADS)

Mullen, J.; Hangarter, R.

Most research on gravity responses in plants has focused on primary roots and shoots, which typically grow in a vertical orientation. However, the patterns of lateral organ formation and their growth orientation, which typically are not vertical, govern plant architecture. For example, in Arabidopsis, when lateral roots emerge from the primary root, they grow at a nearly horizontal orientation. As they elongate, the roots slowly curve until they eventually reach a vertical orientation. The regulation of this lateral root orientation is an important component affecting the overall root system architecture. We have found that this change in orientation is not simply due to the onset of gravitropic competence, as non-vertical lateral roots are capable of both positive and negative gravitropism. Thus, the horizontal growth of the new lateral roots is determined by what is called the gravitropic set-point angle (GSA). In Arabidopsis shoots, rosette leaves and inflorescence branches also display GSA-dependent developmental changes in their orientation. The developmental control of the GSA of lateral organs in Arabidopsis provides us with a useful system for investigating the components involved in regulating directionality of tropistic responses. We have identified several Arabidopsis mutants that have either altered lateral root orientations, altered orientation of lateral organs in the shoot, or both, but maintain normal primary organ orientation. The mgsa ({m}odified {g}ravitropic {s}et-point {a}ngle) mutants with both altered lateral root and shoot orientation show that there are common components in the regulation of growth orientation in the different organs. Rosette leaves and lateral roots also have in common a regulation of positioning by red light. Further molecular and physiological analyses of the GSA mutants will provide insight into the basis of GSA regulation and, thus, a better understanding of how gravity controls plant architecture. [This work was supported by the National Aeronautics and Space Administration through grant no. NCC 2-1200.

[Finite element analysis of the stress distribution of two-piece post crown with different adhesives ].

PubMed

He, Lihui; Liu, Lijie; Gao, Bei; Gao, Shang; Chen, Yifu; Zhihui, Liu

2013-08-01

To establish three-dimensional finite element model of two-piece post crown to the mandibular first molar residual roots, and analyze the stress distribution characteristic to the residual roots with different adhesives, so as to get the best combination under different conditions. The complete mandibular first molar in vitro was selected, the crown was removed along the cemento-enamel junction, then the residual roots were scanned by CT. CT images were imported into a reverse engineering software, and the three-dimensional finite element model of the mandibular first molar residual roots was reconstructed. Titanium two-piece post crown of the mandibular first molar residual roots was produced, then was scanned by CT. The model was reconstructed and assembled by MIMICS. The stress distribution of the root canal and root section under the vertical load and lateral load with different bonding systems were analyzed. Three-dimensional finite element model of two-piece post crown to the mandibular first molar residual roots was established. With the increasing of elastic modulus of the adhesives, the maximum stress within the root canal was also increasing. Elastic modulus of zinc phosphate was the biggest, so the stress within the root canal was the biggest; elastic modulus of Superbond C&B was the smallest, so the stress within the root canal was the smallest. Lateral loading stress was much larger than the vertical load. Under vertical load, the load on the root section was even with different bonding systems. Under lateral load, the maximum stress was much larger than the vertical load. The stress on the root section was minimum using zinc phosphate binder, and the stress on the root section was maximum using Superbond C&B. In two-piece post crown restorations, there is significant difference between different adhesives on tooth protection. When the tooth structure of the root canal orifices is weak, in order to avoid the occurrence of splitting, the larger elastic modulus bonding system is the first choice, such as zinc phosphate binder. When the resistance form of the root canal orifices is good enough but the root is too weak, it is suggested that the smaller elastic modulus bonding system is the first choice, such as Superbond C&B.

Effect of water table fluctuations on phreatophytic root distribution.

PubMed

Tron, Stefania; Laio, Francesco; Ridolfi, Luca

2014-11-07

The vertical root distribution of riparian vegetation plays a relevant role in soil water balance, in the partition of water fluxes into evaporation and transpiration, in the biogeochemistry of hyporheic corridors, in river morphodynamics evolution, and in bioengineering applications. The aim of this work is to assess the effect of the stochastic variability of the river level on the root distribution of phreatophytic plants. A function describing the vertical root profile has been analytically obtained by coupling a white shot noise representation of the river level variability to a description of the dynamics of root growth and decay. The root profile depends on easily determined parameters, linked to stream dynamics, vegetation and soil characteristics. The riparian vegetation of a river characterized by a high variability turns out to have a rooting system spread over larger depths, but with shallower mean root depths. In contrast, a lower river variability determines root profiles with higher mean root depths. Copyright © 2014 Elsevier Ltd. All rights reserved.

Root growth dynamics linked to above-ground growth in walnut (Juglans regia).

PubMed

Contador, Maria Loreto; Comas, Louise H; Metcalf, Samuel G; Stewart, William L; Porris Gomez, Ignacio; Negron, Claudia; Lampinen, Bruce D

2015-07-01

Examination of plant growth below ground is relatively scant compared with that above ground, and is needed to understand whole-plant responses to the environment. This study examines whether the seasonal timing of fine root growth and the spatial distribution of this growth through the soil profile varies in response to canopy manipulation and soil temperature. Plasticity in the seasonal timing and vertical distribution of root production in response to canopy and soil water manipulation was analysed in field-grown walnut (Juglans regia 'Chandler') using minirhizotron techniques. Root production in walnuts followed a unimodal curve, with one marked flush of root growth starting in mid-May, with a peak in mid-June. Root production declined later in the season, corresponding to increased soil temperature, as well as to the period of major carbohydrate allocation to reproduction. Canopy and soil moisture manipulation did not influence the timing of root production, but did influence the vertical distribution of roots through the soil profile. Water deficit appeared to promote root production in deeper soil layers for mining soil water. Canopy removal appeared to promote shallow root production. The findings of this study add to growing evidence that root growth in many ecosystems follows a unimodal curve with one marked flush of root growth in coordination with the initial leaf flush of the season. Root vertical distribution appeared to have greater plasticity than timing of root production in this system, with temperature and/or carbohydrate competition constraining the timing of root growth. Effects on root distribution can have serious impacts on trees, with shallow rooting having negative impacts in years with limited soil water or positive impacts in years with wet springs, and deep rooting having positive impacts on soil water mining from deeper soil layers but negative impacts in years with wet springs. © The Author 2015. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Hydrotropism in pea roots in a porous-tube water delivery system

NASA Technical Reports Server (NTRS)

Takahashi, H.; Brown, C. S.; Dreschel, T. W.; Scott, T. K.; Knott, W. M. (Principal Investigator)

1992-01-01

Orientation of root growth on earth and under microgravity conditions can possibly be controlled by hydrotropism--growth toward a moisture source in the absence of or reduced gravitropism. A porous-tube water delivery system being used for plant growth studies is appropriate for testing this hypothesis since roots can be grown aeroponically in this system. When the roots of the agravitropic mutant pea ageotropum (Pisum sativum L.) were placed vertically in air of 91% relative humidity and 2 to 3 mm from the water-saturated porous tube placed horizontally, the roots responded hydrotropically and grew in a continuous arch along the circular surface of the tube. By contrast, normal gravitropic roots of Alaska' pea initially showed a slight transient curvature toward the tube and then resumed vertical downward growth due to gravitropism. Thus, in microgravity, normal gravitropic roots could respond to a moisture gradient as strongly as the agravitropic roots used in this study. Hydrotropism should be considered a significant factor responsible for orientation of root growth in microgravity.

The effect of EDTA in attachment gain and root coverage.

PubMed

Kassab, Moawia M; Cohen, Robert E; Andreana, Sebastiano; Dentino, Andrew R

2006-06-01

Root surface biomodification using low pH agents such as citric acid and tetracycline has been proposed to enhance root coverage following connective tissue grafting. The authors hypothesized that root conditioning with neutral pH edetic acid would improve vertical recession depth, root surface coverage, pocket depth, and clinical attachment levels. Twenty teeth in 10 patients with Miller class I and II recession were treated with connective tissue grafting. The experimental sites received 24% edetic acid in sterile distilled water applied to the root surface for 2 minutes before grafting. Controls were pretreated with only sterile distilled water. Measurements were evaluated before surgery and 6 months after surgery. Analysis of variance was used to determine differences between experimental and control groups. We found significant postoperative improvements in vertical recession depth, root surface coverage, and clinical attachment levels in test and control groups, compared to postoperative data. Pocket depth differences were not significant (P<.01).

Modeling and analysis of the vertical roots distribution in levees - a case study of the third Rhone correction

NASA Astrophysics Data System (ADS)

Gianetta, Ivan; Schwarz, Massimiliano; Glenz, Christian; Lammeranner, Walter

2013-04-01

In recent years the effects of roots on river banks and levees have been the subject of major discussions. The main issue about the presence of woody vegetation on levees is related to the possibility that roots increase internal erosion processes and the superimposed load of large trees compromise the integrity of these structures. However, ecologists and landscape managers argue that eliminating the natural vegetation from the riverbanks also means eliminating biotopes, strengthening anthropisation of the landscape, as well as limiting recreations areas. In the context of the third correction of the Rhone in Switzerland, the discussion on new levee geometries and the implementation of woody vegetation on them, lead to a detailed analysis of this issue for this specific case. The objective of this study was to describe quantitatively the processes and factors that influence the root distribution on levees and test modeling approaches for the simulation of vertical root distribution with laboratory and field data. An extension of an eco-hydrological analytic model that considers climatic and pedological condition for the quantification of vertical root distribution was validated with data provided by the University of Vienna (BOKU) of willows' roots (Salix purpurea) grown under controlled conditions. Furthermore, root distribution data of four transversal sections of a levee near Visp (canton Wallis, Switzerland) was used to validate the model. The positions of the levee's sections were chosen based on the species and dimensions of the woody vegetation. The dominant species present in the sections were birch (Betula pendula) and poplar (Populus nigra). For each section a grid of 50x50 cm was created to count and measure the roots. The results show that vertical distribution of root density under controlled growing conditions has an exponential form, decreasing with increasing soil depth, and can be well described by the eco-hydrological model. Vice versa, field data of vertical roots distribution show a non-exponential function and cannot fully be described by the model. A compacted layer of stones at about 2 m depth is considered as limiting factor for the rooting depth on the analyzed levee. The collected data and the knowledge gained from quantitative analysis represent the starting point for a discussion on new levee geometries and the development of new strategies for the implementation of woody vegetation on levees. A long term monitoring project for the analysis of the effectiveness of new implementation strategies of vegetation on levees, is considered an important prospective for future studies on this topic.

The possible involvement of root-cap mucilage in gravitropism and calcium movement across root tips of Allium cepa L

NASA Technical Reports Server (NTRS)

Moore, R.; Fondren, W. M.

1986-01-01

Roots of Allium cepa L. grown in aerated water elongate rapidly, but are not graviresponsive. These roots (1) possess extensive columella tissues comprised of cells containing numerous sedimented amyloplasts, (2) lack mucilage on their tips, and (3) are characterized by a weakly polar movement of calcium (Ca) across their tips. Placing roots in humid air correlates positively with the (1) onset of gravicurvature, (2) appearance of mucilage on tips of the roots, and (3) onset of the ability to transport Ca polarly to the lower side of the root tip. Gravicurvature of roots previously submerged in aerated water is more rapid when roots are oriented vertically for 1-2 h in humid air prior to being oriented horizontally. The more rapid gravicurvature of these roots correlates positively with the accumulation of mucilage at the tips of roots during the time the roots are oriented vertically. Therefore, the onset of gravicurvature and the ability of roots to transport Ca to the lower sides of their tips correlate positively with the presence of mucilage at their tips. These results suggest that mucilage may be important for the transport of Ca across root caps.

Vertical Distribution of Pasteuria penetrans Parasitizing Meloidogyne incognita on Pittosporum tobira in Florida.

PubMed

Baidoo, Richard; Mengistu, Tesfamariam Mekete; Brito, Janete A; McSorley, Robert; Stamps, Robert H; Crow, William T

2017-09-01

Pasteuria penetrans is considered as the primary agent responsible for soil suppressiveness to root-knot nematodes widely distributed in many agricultural fields. A preliminary survey on a Pittosporum tobira field where the grower had experienced a continuous decline in productivity caused by Meloidogyne incognita showed that the nematode was infected with Pasteuria penetrans . For effective control of the nematode, the bacterium and the host must coexist in the same root zone. The vertical distribution of Pasteuria penetrans and its relationship with the nematode host in the soil was investigated to identify (i) the vertical distribution of P. penetrans endospores in an irrigated P. tobira field and (ii) the relationship among P. penetrans endospore density, M. incognita J2 population density, and host plant root distribution over time. Soil bioassays revealed that endospore density was greater in the upper 18 cm of the top soil compared with the underlying depths. A correlation analysis showed that the endospore density was positively related to the J2 population density and host plant root distribution. Thus, the vertical distribution of P. penetrans was largely dependent on its nematode host which in turn was determined by the distribution of the host plant roots. The Pasteuria was predominant mostly in the upper layers of the soil where their nematode host and the plant host roots are abundant, a factor which may be a critical consideration when using P. penetrans as a nematode biological control agent.

Vertical Distribution of Pasteuria penetrans Parasitizing Meloidogyne incognita on Pittosporum tobira in Florida

PubMed Central

Baidoo, Richard; Mengistu, Tesfamariam Mekete; Brito, Janete A.; McSorley, Robert; Stamps, Robert H.; Crow, William T.

2017-01-01

Pasteuria penetrans is considered as the primary agent responsible for soil suppressiveness to root-knot nematodes widely distributed in many agricultural fields. A preliminary survey on a Pittosporum tobira field where the grower had experienced a continuous decline in productivity caused by Meloidogyne incognita showed that the nematode was infected with Pasteuria penetrans. For effective control of the nematode, the bacterium and the host must coexist in the same root zone. The vertical distribution of Pasteuria penetrans and its relationship with the nematode host in the soil was investigated to identify (i) the vertical distribution of P. penetrans endospores in an irrigated P. tobira field and (ii) the relationship among P. penetrans endospore density, M. incognita J2 population density, and host plant root distribution over time. Soil bioassays revealed that endospore density was greater in the upper 18 cm of the top soil compared with the underlying depths. A correlation analysis showed that the endospore density was positively related to the J2 population density and host plant root distribution. Thus, the vertical distribution of P. penetrans was largely dependent on its nematode host which in turn was determined by the distribution of the host plant roots. The Pasteuria was predominant mostly in the upper layers of the soil where their nematode host and the plant host roots are abundant, a factor which may be a critical consideration when using P. penetrans as a nematode biological control agent. PMID:29062154

The Performance of a Zirconium-based Root Filling Material with Artifact Reduction Properties in the Detection of Artificially Induced Root Fractures Using Cone-beam Computed Tomographic Imaging.

PubMed

Fox, Aaron; Basrani, Bettina; Lam, Ernest W N

2018-05-01

Limited field of view cone-beam computed tomographic (CBCT) imaging has been used to augment clinical testing of vertical root fractures (VRFs); however, the presence of gutta-percha (GP) in the canal space generates substantial imaging artifacts that make fracture detection difficult. The purpose of this study was to evaluate the influence of a zirconium (Zr)-based root filling material with radiologic properties that reduce beam hardening (BH) artifacts using CBCT imaging in the in vitro diagnosis of VRFs. One hundred seventy-six single-rooted mandibular premolar teeth were obtained, and half of these teeth were filled with GP or Zr (CPoint; EndoTechnologies, LLC, Shrewsbury, MA). VRFs were induced in 44 decoronated teeth in each group using an Instron (Norwood, MA) Universal Testing Machine. Each root was then placed in a dry human mandible and imaged with the Carestream 9000 3D CBCT system (Carestream Dental, Atlanta, GA). The images were evaluated by 6 oral maxillofacial radiologists (OMRs) and residents. The sensitivity was greater for detecting VRFs in the Zr group than the GP group (P = .035). However, the specificity was greater for the GP group than the Zr group (P = .028). Receiver operating characteristic area under the curve values were greater for the Zr group than the GP group, but these differences were not statistically significant. The OMRs outperformed the residents in the detection of VRFs in the Zr group with respect to specificity (P = .006) and positive predictive value (P = .012). The reduced BH of the Zr group improved the sensitivity of the detection of artificially induced VRFs. The ability to detect VRFs in the Zr group was further enhanced by clinical experience. Copyright © 2018 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Active Vertical Tail Buffeting Alleviation on an F/A-18 Model in a Wind Tunnel

NASA Technical Reports Server (NTRS)

Moses, Robert W.

1999-01-01

A 1/6-scale F-18 wind-tunnel model was tested in the Transonic Dynamics Tunnel at the NASA Langley Research Center as part of the Actively Controlled Response Of Buffet-Affected Tails (ACROBAT) program to assess the use of active controls in reducing vertical tail buffeting. The starboard vertical tail was equipped with an active rudder and other aerodynamic devices, and the port vertical tail was equipped with piezoelectric actuators. The tunnel conditions were atmospheric air at a dynamic pressure of 14 psf. By using single-input-single-output control laws at gains well below the physical limits of the control effectors, the power spectral density of the root strains at the frequency of the first bending mode of the vertical tail was reduced by as much as 60 percent up to angles of attack of 37 degrees. Root mean square (RMS) values of root strain were reduced by as much as 19 percent. Stability margins indicate that a constant gain setting in the control law may be used throughout the range of angle of attack tested.

Imaging tree roots with borehole radar

Treesearch

John R. Butnor; Kurt H. Johnsen; Per Wikstrom; Tomas Lundmark; Sune Linder

2006-01-01

Ground-penetrating radar has been used to de-tect and map tree roots using surface-based antennas in reflection mode. On amenable soils these methods can accurately detect lateral tree roots. In some tree species (e.g. Pinus taeda, Pinus palustris), vertically orientated tap roots directly beneath the tree, comprise most of the root mass. It is...

Vertical Root Fracture Detection Using Limited-FOV Cone-Beam Computed Tomography

DTIC Science & Technology

2012-06-01

A thesis submitted to the Faculty of the Endodontics Graduate Program Naval Postgraduate Dental School Uniformed Services...Dental Program Navy Medicine Professional Development Center Terry D. Webb, DDS, MS CAPT, DC, USN Chairman, Endodontics Dept. Glen M. Imamura, S...Computed Tomography Geoffrey McMurray, DDS, MS ABSTRACT Introduction: Vertical root fractures (VRF) often occur in endodontically treated teeth

In-flight flow visualization results from the X-29A aircraft at high angles of attack

NASA Technical Reports Server (NTRS)

Delfrate, John H.; Saltzman, John A.

1992-01-01

Flow visualization techniques were used on the X-29A aircraft at high angles of attack to study the vortical flow off the forebody and the surface flow on the wing and tail. The forebody vortex system was studied because asymmetries in the vortex system were suspected of inducing uncommanded yawing moments at zero sideslip. Smoke enabled visualization of the vortex system and correlation of its orientation with flight yawing moment data. Good agreement was found between vortex system asymmetries and the occurrence of yawing moments. Surface flow on the forward-swept wing of the X-29A was studied using tufts and flow cones. As angle of attack increased, separated flow initiated at the root and spread outboard encompassing the full wing by 30 deg angle of attack. In general, the progression of the separated flow correlated well with subscale model lift data. Surface flow on the vertical tail was also studied using tufts and flow cones. As angle of attack increased, separated flow initiated at the root and spread upward. The area of separated flow on the vertical tail at angles of attack greater than 20 deg correlated well with the marked decrease in aircraft directional stability.

Nursery Cultural Practices and Morphological Arrtibutes of Longleaf Pine Bare-Root Stock as Indicators of Early Field Performance

Treesearch

Glyndon E. Hatchell; H. David Muse

1990-01-01

Longleaf pine seedlings performed satisfactorily after planting on deep sands in South Carolina in dry years when: (1) They were vertically root-pruned in the nursery. (2) They had 14 or more first-order lateral roots and nonfibrous root systems. (3) They had six or more first-order lateral roots and highly fibrous root systems.

Evaluation of three imaging techniques for the detection of vertical root fractures in the absence and presence of gutta-percha root fillings.

PubMed

Khedmat, S; Rouhi, N; Drage, N; Shokouhinejad, N; Nekoofar, M H

2012-11-01

To compare the accuracy of digital radiography (DR), multidetector computed tomography (MDCT) and cone beam computed tomography (CBCT) in detecting vertical root fractures (VRF) in the absence and presence of gutta-percha root filling. The root canals of 100 extracted human single-rooted teeth were prepared and randomly divided into four groups: two experimental groups with artificially fractured root and two intact groups as controls. In one experimental and one control group, a size 40, 0.04 taper gutta-percha cone was inserted in the root canals. Then DR, MDCT and CBCT were performed and the images evaluated. Statistical analyses of sensitivity, specificity and accuracy of each imaging technique in the presence and absence of gutta-percha were calculated and compared. In the absence of gutta-percha, the specificity of DR, MDCT and CBCT was similar. CBCT was the most accurate and sensitive imaging technique (P < 0 .05). In the presence of gutta-percha, the accuracy of MDCT was higher than the other imaging techniques (P < 0.05). The sensitivity of CBCT and MDCT was significantly higher than that of DR (P < 0.05), whereas CBCT was the least specific technique. Under the conditions of this ex vivo study, CBCT was the most sensitive imaging technique in detecting vertical root fracture. The presence of gutta-percha reduced the accuracy, sensitivity and specificity of CBCT but not MDCT. The sensitivity of DR was reduced in the presence of gutta-percha. The use of MDCT as an alternative technique may be recommended when VRF are suspected in root filled teeth. However, as the radiation dose of MDCT is higher than CBCT, the technique could be considered at variance with the principles of ALARA. © 2012 International Endodontic Journal.

Apical root resorption of incisors after orthodontic treatment of impacted maxillary canines: a radiographic study.

PubMed

Brusveen, Elin Marie Gravdal; Brudvik, Pongsri; Bøe, Olav Egil; Mavragani, Maria

2012-04-01

The purpose of the study was to evaluate impacted maxillary canines as risk factor for orthodontic apical root resorption. The sample comprised 66 patients treated with fixed appliances. Thirty-two patients with a unilateral impacted maxillary canine, which was distanced from the roots of the incisors at a preliminary phase of treatment before bonding, formed the impaction group, and 34 patients without impactions served as the controls. Root shortening was calculated by using pretreatment and posttreatment intraoral radiographs. Inclination of the eruption path of the impacted canine relative to the midline, axis of the lateral incisor, and nasal line, root development, and the medial and vertical positions of the impacted tooth were recorded on orthopantomograms and lateral cephalometric films. The follicle/tooth ratio was evaluated by using periapical radiographs. No significant difference in apical resorption of the maxillary incisors was detected between the impaction and control groups, or between the incisors of the impacted and contralateral sides in the same subject. Likewise, no difference in the severity of root resorption was found between the incisors of impacted side alone and the incisors of the control group. Mesial and vertical inclinations of the impacted canines were negatively related to a lateral incisor's root resorption. No correlations were found between resorption and medial or vertical position of the crown of the canine. The follicle/tooth ratio was significantly related to the mesial inclination of the impacted canine, but not to root resorption. An impacted maxillary canine, after being distanced from the incisor roots, does not seem to be a risk factor for apical root resorption during orthodontic treatment. Copyright © 2012 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Vertical Tail Buffeting Alleviation Using Piezoelectric Actuators: Some Results of the Actively Controlled Response of Buffet-Affected Tails (ACROBAT) Program

NASA Technical Reports Server (NTRS)

Moses, Robert W.

1997-01-01

A 1/6-scale F-18 wind-tunnel model was tested in the Transonic Dynamics Tunnel at the NASA Langley Research Center as part of the Actively Controlled Response Of Buffet Affected Tails (ACROBAT) program to assess the use of active controls in reducing vertical tail buffeting. The starboard vertical tail was equipped with an active rudder and the port vertical tail was equipped with piezoelectric actuators. The tunnel conditions were atmospheric air at a dynamic pressure of 14 psf. By using single-input-single-output control laws at gains well below the physical limits of the actuators, the power spectral density of the root strains at the frequency of the first bending mode of the vertical tail was reduced by as much as 60 percent up to angles of attack of 37 degrees. Root mean square (RMS) values of root strain were reduced by as much as 19 percent. Buffeting alleviation results when using the rudder are presented for comparison. Stability margins indicate that a constant gain setting in the control law may be used throughout the range of angle of attack tested.

Development of a 3D Soil-Plant-Atmosphere Continuum (SPAC) coupled to a Land Surface Model

NASA Astrophysics Data System (ADS)

Bisht, G.; Riley, W. J.; Lorenzetti, D.; Tang, J.

2015-12-01

Exchange of water between the atmosphere and biosphere via evapotranspiration (ET) influences global hydrological, energy, and biogeochemical cycles. Isotopic analysis has shown that evapotranspiration over the continents is largely dominated by transpiration. Water is taken up from soil by plant roots, transported through the plant's vascular system, and evaporated from the leaves. Yet current Land Surface Models (LSMs) integrated into Earth System Models (ESMs) treat plant roots as passive components. These models distribute the ET sink vertically over the soil column, neglect the vertical pressure distribution along the plant vascular system, and assume that leaves can directly access water from any soil layer within the root zone. Numerous studies have suggested that increased warming due to climate change will lead drought and heat-induced tree mortality. A more mechanistic treatment of water dynamics in the soil-plant-atmosphere continuum (SPAC) is essential for investigating the fate of ecosystems under a warmer climate. In this work, we describe a 3D SPAC model that can be coupled to a LSM. The SPAC model uses the variably saturated Richards equations to simulate water transport. The model uses individual governing equations and constitutive relationships for the various SPAC components (i.e., soil, root, and xylem). Finite volume spatial discretization and backward Euler temporal discretization is used to solve the SPAC model. The Portable, Extensible Toolkit for Scientific Computation (PETSc) is used to numerically integrate the discretized system of equations. Furthermore, PETSc's multi-physics coupling capability (DMComposite) is used to solve the tightly coupled system of equations of the SPAC model. Numerical results are presented for multiple test problems.

The effect of spaceflight on the gravity-sensing auxin gradient of roots: GFP reporter gene microscopy on orbit

PubMed Central

Ferl, Robert J; Paul, Anna-Lisa

2016-01-01

Our primary aim was to determine whether gravity has a direct role in establishing the auxin-mediated gravity-sensing system in primary roots. Major plant architectures have long been thought to be guided by gravity, including the directional growth of the primary root via auxin gradients that are then disturbed when roots deviate from the vertical as a gravity sensor. However, experiments on the International Space Station (ISS) now allow physical clarity with regard to any assumptions regarding the role of gravity in establishing fundamental root auxin distributions. We examined the spaceflight green fluorescent protein (GFP)-reporter gene expression in roots of transgenic lines of Arabidopsis thaliana: pDR5r::GFP, pTAA1::TAA1–GFP, pSCR::SCR–GFP to monitor auxin and pARR5::GFP to monitor cytokinin. Plants on the ISS were imaged live with the Light Microscopy Module (LMM), and compared with control plants imaged on the ground. Preserved spaceflight and ground control plants were examined post flight with confocal microscopy. Plants on orbit, growing in the absence of any physical reference to the terrestrial gravity vector, displayed typically “vertical” distribution of auxin in the primary root. This confirms that the establishment of the auxin-gradient system, the primary guide for gravity signaling in the root, is gravity independent. The cytokinin distribution in the root tip differs between spaceflight and the ground controls, suggesting spaceflight-induced features of root growth may be cytokinin related. The distribution of auxin in the gravity-sensing portion of the root is not dependent on gravity. Spaceflight appears benign to auxin and its role in the development of the primary root tip, whereas spaceflight may influence cytokinin-associated processes. PMID:28725721

Spatial separation of light perception and growth response in maize root phototropism.

PubMed

Mullen, J L; Wolverton, C; Ishikawa, H; Hangarter, R P; Evans, M L

2002-09-01

Although the effects of gravity on root growth are well known and interactions between light and gravity have been reported, details of root phototropic responses are less documented. We used high-resolution image analysis to study phototropism in primary roots of Zea mays L. Similar to the location of perception in gravitropism, the perception of light was localized in the root cap. Phototropic curvature away from the light, on the other hand, developed in the central elongation zone, more basal than the site of initiation of gravitropic curvature. The phototropic curvature saturated at approximately 10 micromoles m-2 s-1 blue light with a peak curvature of 29 +/- 4 degrees, in part due to induction of positive gravitropism following displacement of the root tip from vertical during negative phototropism. However, at higher fluence rates, development of phototropic curvature is arrested even if gravitropism is avoided by maintaining the root cap vertically using a rotating feedback system. Thus continuous illumination can cause adaptation in the signalling pathway of the phototropic response in roots.

Spatial separation of light perception and growth response in maize root phototropism

NASA Technical Reports Server (NTRS)

Mullen, J. L.; Wolverton, C.; Ishikawa, H.; Hangarter, R. P.; Evans, M. L.

2002-01-01

Although the effects of gravity on root growth are well known and interactions between light and gravity have been reported, details of root phototropic responses are less documented. We used high-resolution image analysis to study phototropism in primary roots of Zea mays L. Similar to the location of perception in gravitropism, the perception of light was localized in the root cap. Phototropic curvature away from the light, on the other hand, developed in the central elongation zone, more basal than the site of initiation of gravitropic curvature. The phototropic curvature saturated at approximately 10 micromoles m-2 s-1 blue light with a peak curvature of 29 +/- 4 degrees, in part due to induction of positive gravitropism following displacement of the root tip from vertical during negative phototropism. However, at higher fluence rates, development of phototropic curvature is arrested even if gravitropism is avoided by maintaining the root cap vertically using a rotating feedback system. Thus continuous illumination can cause adaptation in the signalling pathway of the phototropic response in roots.

Preferential flow and pesticide transport in a clay-rich till: Field, laboratory, and modeling analysis

NASA Astrophysics Data System (ADS)

JøRgensen, Peter R.; Hoffmann, Martin; Kistrup, Jens P.; Bryde, Claus; Bossi, Rossana; Villholth, Karen G.

2002-11-01

This study investigates vertical flow and pesticide transport along fractures in water saturated unoxidized clayey till. From two experimental fields, each 40 m2, 96% and 98%, respectively, of total vertical flow was conducted along fractures in the till, while the remaining 2-4% of flow occurred in the clay matrix at very slow flow rate. An applied dye tracer was observed only along 10-26% of the total fracture length measured on the horizontal surface of the experimental fields. In vertical sections the dyed fracture portions constituted root channels, which penetrated the till vertically along the fractures into the local aquifer at 5 m depth. No dye tracer was observed in the fractures without root channels or in the unfractured clay matrix, suggesting that root growth along the fracture surfaces was the principal agent of fracture aperture enhancement. Using hydraulic fracture aperture values determined from large undisturbed column (LUC) collected from one of the experimental fields, it was estimated that 94% of flow in the fractures was conducted along the fracture root channels, while only 6% of flow was conducted along the fracture sections without root channels. For natural vertical hydraulic gradients (0.8-2.3 at the site), flow rates of 0.8-2 km/d were determined for a fracture root channel, while fracture sections without root channels revealed flow rates of 9-22 m/d. Corresponding flow rates in the unfractured matrix were 7-19 mm/yr. For infiltrated bromide (nonreactive tracer) and mobile pesticides mecoprop (MCPP) and metsulfuron, very rapid migration (0.28-0.5 m/d) and high relative breakthrough concentrations (30-60%) into the aquifer were observed to occur along the fracture root channels using a constant hydraulic gradient of 1. Only traces were measured from infiltration of the strongly sorbed pesticide prochloraz. The concentrations of the bromide and pesticides in the monitoring wells were modeled with a discrete fracture matrix diffusion (DFDM) model coupled with a single porosity model (SP) for the till and aquifer, respectively. Using effective fracture spacings and mean fracture apertures for the fracture channel sections as modeling input parameters for the till, the concentrations observed in the wells of the aquifer could be reasonably approximated.

Helicopter theory

NASA Technical Reports Server (NTRS)

Johnson, W.

1980-01-01

A comprehensive presentation is made of the engineering analysis methods used in the design, development and evaluation of helicopters. After an introduction covering the fundamentals of helicopter rotors, configuration and operation, rotary wing history, and the analytical notation used in the text, the following topics are discussed: (1) vertical flight, including momentum, blade element and vortex theories, induced power, vertical drag and ground effect; (2) forward flight, including in addition to momentum and vortex theory for this mode such phenomena as rotor flapping and its higher harmonics, tip loss and root cutout, compressibility and pitch-flap coupling; (3) hover and forward flight performance assessment; (4) helicopter rotor design; (5) rotary wing aerodynamics; (6) rotary wing structural dynamics, including flutter, flap-lag dynamics ground resonance and vibration and loads; (7) helicopter aeroelasticity; (8) stability and control (flying qualities); (9) stall; and (10) noise.

Vertical Tail Buffeting Alleviation Using Piezoelectric Actuators-Some Results of the Actively Controlled Response of Buffet-Affected Tails (ACROBAT) Program

NASA Technical Reports Server (NTRS)

Moses, Robert W.

1997-01-01

Buffet is an aeroelastic phenomenon associated with high performance aircraft especially those with twin vertical tails. In particular, for the F/A-18 aircraft at high angles of attack, vortices emanating from wing/fuselage leading edge extensions burst, immersing the vertical tails in their wake. The resulting buffet loads on the vertical tails are a concern from fatigue and inspection points of view. Recently, a 1/6-scale F-18 wind-tunnel model was tested in the Transonic Dynamics Tunnel at the NASA Langley Research Center as part of the Actively Controlled Response Of Buffet Affected Tails (ACROBAT) Program to assess the use of active controls in reducing vertical tail buffeting. The starboard vertical tail was equipped with an active rudder and the port vertical tail was equipped with piezoelectric actuators. The tunnel conditions were atmospheric air at Mach 0.10. By using single-input-single-output control laws at gains well below the physical limits of the actuators, the power spectral density of the root strains at the frequency of the first bending mode of the vertical tail was reduced by as much as 60 percent up to angles of attack of 37 degrees. Root mean square (RMS) values of root strain were reduced by as much as 19 percent. The results herein illustrate that buffet alleviation of vertical tails can be accomplished using simple active control of the rudder or piezoelectric actuators. In fact, as demonstrated herein, a fixed gain single input single output control law that commands piezoelectric actuators may be active throughout the high angle-of-attack maneuver without requiring any changes during the maneuver. Future tests are mentioned for accentuating the international interest in this area of research.

Hydrotropism and its interaction with gravitropism in maize roots

NASA Technical Reports Server (NTRS)

Takahashi, H.; Scott, T. K.

1991-01-01

We have partially characterized root hydrotropism and its interaction with gravitropism in maize (Zea mays L.). Roots of Golden Cross Bantam 70, which require light for orthogravitropism, showed positive hydrotropism; bending upward when placed horizontally below a hydrostimulant (moist cheesecloth) in 85% relative humidity (RH) and in total darkness. However, the light-exposed roots of Golden Cross Bantam 70 or roots of a normal maize cultivar, Burpee Snow Cross, showed positive gravitropism under the same conditions; bending downward when placed horizontally below the hydrostimulant in 85% RH. Light-exposed roots of Golden Cross Bantam 70 placed at 70 degrees below the horizontal plane responded positively hydrotropically, but gravitropism overcame the hydrotropism when the roots were placed at 45 degrees below the horizontal. Roots placed vertically with the tip down in 85% RH bent to the side toward the hydrostimulant in both cultivars, and light conditions did not affect the response. Such vertical roots did not respond when the humidity was maintained near saturation. These results suggest that hydrotropic and gravitropic responses interact with one another depending on the intensity of one or both factors. Removal of the approximately 1.5 millimeter root tip blocked both hydrotropic and gravitropic responses in the two cultivars. However, removal of visible root tip mucilage did not affect hydrotropism or gravitropism in either cultivar.

Mapping the functional roles of cap cells in the response of Arabidopsis primary roots to gravity

NASA Technical Reports Server (NTRS)

Blancaflor, E. B.; Fasano, J. M.; Gilroy, S.; Evans, M. L. (Principal Investigator)

1998-01-01

The cap is widely accepted to be the site of gravity sensing in roots because removal of the cap abolishes root curvature. Circumstantial evidence favors the columella cells as the gravisensory cells because amyloplasts (and often other cellular components) are polarized with respect to the gravity vector. However, there has been no functional confirmation of their role. To address this problem, we used laser ablation to remove defined cells in the cap of Arabidopsis primary roots and quantified the response of the roots to gravity using three parameters: time course of curvature, presentation time, and deviation from vertical growth. Ablation of the peripheral cap cells and tip cells did not alter root curvature. Ablation of the innermost columella cells caused the strongest inhibitory effect on root curvature without affecting growth rates. Many of these roots deviated significantly from vertical growth and had a presentation time 6-fold longer than the controls. Among the two inner columella stories, the central cells of story 2 contributed the most to root gravitropism. These cells also exhibited the largest amyloplast sedimentation velocities. Therefore, these results are consistent with the starch-statolith sedimentation hypothesis for gravity sensing.

Performance of deep-rooted phreatophytic trees at a site containing total petroleum hydrocarbons.

PubMed

Ferro, Ari M; Adham, Tareq; Berra, Brett; Tsao, David

2013-01-01

Poplar and willow tree stands were installed in 2003 at a site in Raleigh, North Carolina containing total petroleum hydrocarbon - contaminated groundwater. The objective was groundwater uptake and plume control. The water table was 5 to 6 m below ground surface (bgs) and therefore methods were used to encourage deep root development. Growth rates, rooting depth and sap flow were measured for trees in Plot A located in the center of the plume and in Plot B peripheral to the plume. The trees were initially sub-irrigated with vertically installed drip-lines and by 2005 had roots 4 to 5 m bgs. Water balance calculations suggested groundwater uptake. In 2007, the average sap flow was higher for Plot B (approximately 59 L per day per tree) than for Plot A (approximately 23 L per day per tree), probably as a result of TPH-induced stress in Plot A. Nevertheless, the estimated rate of groundwater uptake for Plot A was sufficient, relative to the calculated rate of groundwater flux beneath the stand, that a high level of plume control was achieved based on MODFLOW modeling results. Down-gradient groundwater monitoring wells installed in late 2011 should provide quantitative data for plume control.

Control of gravitropic orientation. II. Dual receptor model for gravitropism

NASA Technical Reports Server (NTRS)

LaMotte, Clifford E.; Pickard, Barbara G.

2004-01-01

Gravitropism of vascular plants has been assumed to require a single gravity receptor mechanism. However, based on the evidence in Part I of this study, we propose that maize roots require two. The first mechanism is without a directional effect and, by itself, cannot give rise to tropism. Its role is quantitative facilitation of the second mechanism, which is directional like the gravitational force itself and provides the impetus for tropic curvature. How closely coupled the two mechanisms may be is, as yet, unclear. The evidence for dual receptors supports a general model for roots. When readiness for gravifacilitation, or gravifacilitation itself, is constitutive, orthogravitropic curvature can go to completion. If not constitutively enabled, gravifacilitation can be weak in the absence of light and water deficit or strong in the presence of light and water deficit. In either case, it can decay and permit roots to assume reproducible non-vertical orientations (plagiogravitropic or plagiotropic orientations) without using non-vertical setpoints. In this way roots are deployed in a large volume of soil. Gravitropic behaviours in shoots are more diverse than in roots, utilising oblique and horizontal as well as vertical setpoints. As a guide to future experiments, we assess how constitutive v. non-constitutive modes of gravifacilitation might contribute to behaviours based on each kind of setpoint.

Bouldering: an alternative strategy to long-vertical climbing in root-climbing hortensias

PubMed Central

Granados Mendoza, Carolina; Isnard, Sandrine; Charles-Dominique, Tristan; Van den Bulcke, Jan; Rowe, Nick P.; Van Acker, Joris; Goetghebeur, Paul; Samain, Marie-Stéphanie

2014-01-01

In the Neotropics, the genus Hydrangea of the popular ornamental hortensia family is represented by climbing species that strongly cling to their support surface by means of adhesive roots closely positioned along specialized anchoring stems. These root-climbing hortensia species belong to the nearly exclusive American Hydrangea section Cornidia and generally are long lianescent climbers that mostly flower and fructify high in the host tree canopy. The Mexican species Hydrangea seemannii, however, encompasses not only long lianescent climbers of large vertical rock walls and coniferous trees, but also short ‘shrub-like’ climbers on small rounded boulders. To investigate growth form plasticity in root-climbing hortensia species, we tested the hypothesis that support variability (e.g. differences in size and shape) promotes plastic responses observable at the mechanical, structural and anatomical level. Stem bending properties, architectural axis categorization, tissue organization and wood density were compared between boulder and long-vertical tree-climbers of H. seemannii. For comparison, the mechanical patterns of a closely related, strictly long-vertical tree-climbing species were investigated. Hydrangea seemannii has fine-tuned morphological, mechanical and anatomical responses to support variability suggesting the presence of two alternative root-climbing strategies that are optimized for their particular environmental conditions. Our results suggest that variation of some stem anatomical traits provides a buffering effect that regulates the mechanical and hydraulic demands of two distinct plant architectures. The adaptive value of observed plastic responses and the importance of considering growth form plasticity in evolutionary and conservation studies are discussed. PMID:25079869

Potential relationship between design of nickel-titanium rotary instruments and vertical root fracture.

PubMed

Kim, Hyeon-Cheol; Lee, Min-Ho; Yum, Jiwan; Versluis, Antheunis; Lee, Chan-Joo; Kim, Byung-Min

2010-07-01

Nickel-titanium (NiTi) rotary files can produce cleanly tapered canal shapes with low tendency of transporting the canal lumen. Because NiTi instruments are generally perceived to have high fracture risk during use, new designs have been marketed to lower fracture risks. However, these design variations may also alter the forces on a root during instrumentation and increase dentinal defects that predispose a root to fracture. This study compared the stress conditions during rotary instrumentation in a curved root for three NiTi file designs. Stresses were calculated using finite element (FE) analysis. FE models of ProFile (Dentsply Maillefer, Ballaigues, Switzerland; U-shaped cross-section and constant 6% tapered shaft), ProTaper Universal (Dentsply; convex triangular cross-section with notch and progressive taper shaft), and LightSpeed LSX (Lightspeed Technology, Inc, San Antonio, TX; noncutting round shaft) were rotated within a curved root canal. The stress and strain conditions resulting from the simulated shaping action were evaluated in the apical root dentin. ProTaper Universal induced the highest von Mises stress concentration in the root dentin and had the highest tensile and compressive principal strain components at the external root surface. The calculated stress values from ProTaper Universal, which had the biggest taper shaft, approached the strength properties of dentin. LightSpeed generated the lowest stresses. The stiffer file designs generated higher stress concentrations in the apical root dentin during shaping of the curved canal, which raises the risk of dentinal defects that may lead to apical root cracking. Thus, stress levels during shaping and fracture susceptibility after shaping vary with instrument design. Copyright 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Determinate primary root growth as an adaptation to aridity in Cactaceae: towards an understanding of the evolution and genetic control of the trait

PubMed Central

Shishkova, Svetlana; Las Peñas, María Laura; Napsucialy-Mendivil, Selene; Matvienko, Marta; Kozik, Alex; Montiel, Jesús; Patiño, Anallely; Dubrovsky, Joseph G.

2013-01-01

Background and Aims Species of Cactaceae are well adapted to arid habitats. Determinate growth of the primary root, which involves early and complete root apical meristem (RAM) exhaustion and differentiation of cells at the root tip, has been reported for some Cactoideae species as a root adaptation to aridity. In this study, the primary root growth patterns of Cactaceae taxa from diverse habitats are classified as being determinate or indeterminate, and the molecular mechanisms underlying RAM maintenance in Cactaceae are explored. Genes that were induced in the primary root of Stenocereus gummosus before RAM exhaustion are identified. Methods Primary root growth was analysed in Cactaceae seedlings cultivated in vertically oriented Petri dishes. Differentially expressed transcripts were identified after reverse northern blots of clones from a suppression subtractive hybridization cDNA library. Key Results All species analysed from six tribes of the Cactoideae subfamily that inhabit arid and semi-arid regions exhibited determinate primary root growth. However, species from the Hylocereeae tribe, which inhabit mesic regions, exhibited mostly indeterminate primary root growth. Preliminary results suggest that seedlings of members of the Opuntioideae subfamily have mostly determinate primary root growth, whereas those of the Maihuenioideae and Pereskioideae subfamilies have mostly indeterminate primary root growth. Seven selected transcripts encoding homologues of heat stress transcription factor B4, histone deacetylase, fibrillarin, phosphoethanolamine methyltransferase, cytochrome P450 and gibberellin-regulated protein were upregulated in S. gummosus root tips during the initial growth phase. Conclusions Primary root growth in Cactoideae species matches their environment. The data imply that determinate growth of the primary root became fixed after separation of the Cactiodeae/Opuntioideae and Maihuenioideae/Pereskioideae lineages, and that the genetic regulation of RAM maintenance and its loss in Cactaceae is orchestrated by genes involved in the regulation of gene expression, signalling, and redox and hormonal responses. PMID:23666887

Determinate primary root growth as an adaptation to aridity in Cactaceae: towards an understanding of the evolution and genetic control of the trait.

PubMed

Shishkova, Svetlana; Las Peñas, María Laura; Napsucialy-Mendivil, Selene; Matvienko, Marta; Kozik, Alex; Montiel, Jesús; Patiño, Anallely; Dubrovsky, Joseph G

2013-07-01

Species of Cactaceae are well adapted to arid habitats. Determinate growth of the primary root, which involves early and complete root apical meristem (RAM) exhaustion and differentiation of cells at the root tip, has been reported for some Cactoideae species as a root adaptation to aridity. In this study, the primary root growth patterns of Cactaceae taxa from diverse habitats are classified as being determinate or indeterminate, and the molecular mechanisms underlying RAM maintenance in Cactaceae are explored. Genes that were induced in the primary root of Stenocereus gummosus before RAM exhaustion are identified. Primary root growth was analysed in Cactaceae seedlings cultivated in vertically oriented Petri dishes. Differentially expressed transcripts were identified after reverse northern blots of clones from a suppression subtractive hybridization cDNA library. All species analysed from six tribes of the Cactoideae subfamily that inhabit arid and semi-arid regions exhibited determinate primary root growth. However, species from the Hylocereeae tribe, which inhabit mesic regions, exhibited mostly indeterminate primary root growth. Preliminary results suggest that seedlings of members of the Opuntioideae subfamily have mostly determinate primary root growth, whereas those of the Maihuenioideae and Pereskioideae subfamilies have mostly indeterminate primary root growth. Seven selected transcripts encoding homologues of heat stress transcription factor B4, histone deacetylase, fibrillarin, phosphoethanolamine methyltransferase, cytochrome P450 and gibberellin-regulated protein were upregulated in S. gummosus root tips during the initial growth phase. Primary root growth in Cactoideae species matches their environment. The data imply that determinate growth of the primary root became fixed after separation of the Cactiodeae/Opuntioideae and Maihuenioideae/Pereskioideae lineages, and that the genetic regulation of RAM maintenance and its loss in Cactaceae is orchestrated by genes involved in the regulation of gene expression, signalling, and redox and hormonal responses.

A Soil-Plate Based Pipeline for Assessing Cereal Root Growth in Response to Polyethylene Glycol (PEG)-Induced Water Deficit Stress

PubMed Central

Nelson, Sven K.; Oliver, Melvin J.

2017-01-01

Drought is a serious problem that causes losses in crop-yield every year, but the mechanisms underlying how roots respond to water deficit are difficult to study under controlled conditions. Methods for assaying root elongation and architecture, especially for seedlings, are commonly achieved on artificial media, such as agar, moistened filter paper, or in hydroponic systems. However, it has been demonstrated that measuring root characteristics under such conditions does not accurately mimic what is observed when plants are grown in soil. Morphological changes in root behavior occur because of differences in solute diffusion, mechanical impedance, exposure to light (in some designs), and gas exchange of roots grown under these conditions. To address such deficiencies, we developed a quantitative method for assaying seedling root lengths and germination in soil using a plate-based approach with wheat as a model crop. We also further developed the method to include defined water deficits stress levels using the osmotic properties of polyethylene glycol (PEG). Seeds were sown into soil-filled vertical plates and grown in the dark. Root length measurements were collected using digital photography through the transparent lid under green lighting to avoid effects of white light exposure on growth. Photographs were analyzed using the cross-platform ImageJ plugin, SmartRoot, which can detect root edges and partially automate root detection for extraction of lengths. This allowed for quick measurements and straightforward and accurate assessments of non-linear roots. Other measurements, such as root width or angle, can also be collected by this method. An R function was developed to collect exported root length data, process and reformat the data, and output plots depicting root/shoot growth dynamics. For water deficit experiments, seedlings were transplanted side-by-side into well-watered plates and plates containing PEG solutions to simulate precise water deficits. PMID:28785272

A Soil-Plate Based Pipeline for Assessing Cereal Root Growth in Response to Polyethylene Glycol (PEG)-Induced Water Deficit Stress.

PubMed

Nelson, Sven K; Oliver, Melvin J

2017-01-01

Drought is a serious problem that causes losses in crop-yield every year, but the mechanisms underlying how roots respond to water deficit are difficult to study under controlled conditions. Methods for assaying root elongation and architecture, especially for seedlings, are commonly achieved on artificial media, such as agar, moistened filter paper, or in hydroponic systems. However, it has been demonstrated that measuring root characteristics under such conditions does not accurately mimic what is observed when plants are grown in soil. Morphological changes in root behavior occur because of differences in solute diffusion, mechanical impedance, exposure to light (in some designs), and gas exchange of roots grown under these conditions. To address such deficiencies, we developed a quantitative method for assaying seedling root lengths and germination in soil using a plate-based approach with wheat as a model crop. We also further developed the method to include defined water deficits stress levels using the osmotic properties of polyethylene glycol (PEG). Seeds were sown into soil-filled vertical plates and grown in the dark. Root length measurements were collected using digital photography through the transparent lid under green lighting to avoid effects of white light exposure on growth. Photographs were analyzed using the cross-platform ImageJ plugin, SmartRoot, which can detect root edges and partially automate root detection for extraction of lengths. This allowed for quick measurements and straightforward and accurate assessments of non-linear roots. Other measurements, such as root width or angle, can also be collected by this method. An R function was developed to collect exported root length data, process and reformat the data, and output plots depicting root/shoot growth dynamics. For water deficit experiments, seedlings were transplanted side-by-side into well-watered plates and plates containing PEG solutions to simulate precise water deficits.

Nitrate-Regulated Glutaredoxins Control Arabidopsis Primary Root Growth1[OPEN

PubMed Central

Walters, Laura A.; Cooper, Andrew M.; Olvera, Jocelyn G.; Rosas, Miguel A.; Rasmusson, Allan G.

2016-01-01

Nitrogen is an essential soil nutrient for plants, and lack of nitrogen commonly limits plant growth. Soil nitrogen is typically available to plants in two inorganic forms: nitrate and ammonium. To better understand how nitrate and ammonium differentially affect plant metabolism and development, we performed transcriptional profiling of the shoots of ammonium-supplied and nitrate-supplied Arabidopsis (Arabidopsis thaliana) plants. Seven genes encoding class III glutaredoxins were found to be strongly and specifically induced by nitrate. RNA silencing of four of these glutaredoxin genes (AtGRXS3/4/5/8) resulted in plants with increased primary root length (approximately 25% longer than the wild type) and decreased sensitivity to nitrate-mediated inhibition of primary root growth. Increased primary root growth is also a well-characterized phenotype of many cytokinin-deficient plant lines. We determined that nitrate induction of glutaredoxin gene expression was dependent upon cytokinin signaling and that cytokinins could activate glutaredoxin gene expression independent of plant nitrate status. In addition, crosses between “long-root” cytokinin-deficient plants and “long-root” glutaredoxin-silenced plants generated hybrids that displayed no further increase in primary root length (i.e. epistasis). Collectively, these findings suggest that AtGRXS3/4/5/8 operate downstream of cytokinins in a signal transduction pathway that negatively regulates plant primary root growth in response to nitrate. This pathway could allow Arabidopsis to actively discriminate between different nitrogen sources in the soil, with the preferred nitrogen source, nitrate, acting to suppress primary root growth (vertical dimension) in concert with its well-characterized stimulatory effect on lateral root growth (horizontal dimension). PMID:26662603

Soil weathering agents are limited where deep tree roots are removed, even after decades of forest regeneration

NASA Astrophysics Data System (ADS)

Billings, S. A.; Richter, D. D., Jr.; Hirmas, D.; Lehmeier, C.; Bagchi, S.; Brecheisen, Z.; Sullivan, P. L.; Min, K.; Hauser, E.; Stair, R.; Flournoy, R.

2017-12-01

Deep roots pump reduced C deep into Earth's critical zone (CZ) as they grow and function. This action generates acid-forming CO2 and organic acids (OA) and fosters microbes that also produce these weathering agents. This phenomenon results in a regolith-weathering reaction front that propagates down with vertical root extension and water infiltration. Across old-growth hardwood, younger pine, and annual crop plots at the Calhoun Critical Zone Observatory, we tested the hypothesis that persistent absence of deep roots, a widespread anthropogenic phenomenon, reduces root- and microbially-mediated biogeochemical pools and fluxes important for weathering, even well below maximum root density. We also hypothesized that land use effects on deep soil biogeochemistry is evident even after decades of forest regeneration. Root abundance to 2 m declined with depth, and was greater in old-growth and regenerating forests than in crop plots at most depths. Old-growth soils also contain more roots than younger pine soils: between 30-45 and 70-80 cm depth, old-growth root abundances were greater than in regenerating forests, and old-growth soils exhibited root distributions with less severe declines with depth and harbored more root-associated bacteria than younger forests. Changing root abundances influenced concentrations of weathering agents. At 3 m, in situ soil [CO2] reached 6%, 4%, and 2% in old-growth, regenerating, and crop soils, respectively. Soil organic C (SOC) and extractable OC (EOC, an OA proxy) did not differ across land use, but at 4-5 m EOC/SOC was higher in old-growth compared to regenerating forests and crop soils (20.0±2.6 vs. 2.0±1.0%). We suggest that biogeochemistry deep beneath old-growth forests reflects greater root prevalence and propensity for generation of weathering agents, and that disturbance regimes inducing deep root mortality impose top-down signals relevant to weathering processes deep in Earth's CZ even after decades of forest regeneration.

Damping ratio analysis of tooth stability under various simulated degrees of vertical alveolar bone loss and different root types.

PubMed

Ho, Kuo-Ning; Lee, Sheng-Yang; Huang, Haw-Ming

2017-08-03

The purpose of this study was to evaluate the feasibility of using damping ratio (DR) analysis combined with resonance frequency (RF) and periotest (PTV) analyses to provide additional information about natural tooth stability under various simulated degrees of alveolar vertical bone loss and various root types. Three experimental tooth models, including upper central incisor, upper first premolar, and upper first molar were fabricated using Ti6Al4V alloy. In the tooth models, the periodontal ligament and alveolar bone were simulated using a soft lining material and gypsum, respectively. Various degrees of vertical bone loss were simulated by decreasing the surrounding bone level apically from the cementoenamel junction in 2-mm steps incrementally downward for 10 mm. A commercially available RF analyzer was used to measure the RF and DR of impulse-forced vibrations on the tooth models. The results showed that DRs increased as alveolar vertical bone height decreased and had high coefficients of determination in the linear regression analysis. The damping ratio of the central incisor model without a simulated periodontal ligament were 11.95 ± 1.92 and 27.50 ± 0.67% respectively when their bone levels were set at 2 and 10 mm apically from the cementoenamel junction. These values significantly changed to 28.85 ± 2.54% (p = 0.000) and 51.25 ± 4.78% (p = 0.003) when the tooth model was covered with simulated periodontal ligament. Moreover, teeth with different root types showed different DR and RF patterns. Teeth with multiple roots had lower DRs than teeth with single roots. Damping ratio analysis combined with PTV and RF analysis provides more useful information on the assessment of changes in vertical alveolar bone loss than PTV or RF analysis alone.

Phenotyping for the dynamics of field wheat root system architecture

NASA Astrophysics Data System (ADS)

Chen, Xinxin; Ding, Qishuo; Błaszkiewicz, Zbigniew; Sun, Jiuai; Sun, Qian; He, Ruiyin; Li, Yinian

2017-01-01

We investigated a method to quantify field-state wheat RSA in a phenotyping way, depicting the 3D topology of wheat RSA in 14d periods. The phenotyping procedure, proposed for understanding the spatio-temporal variations of root-soil interaction and the RSA dynamics in the field, is realized with a set of indices of mm scale precision, illustrating the gradients of both wheat root angle and elongation rate along soil depth, as well as the foraging potential along the side directions. The 70d was identified as the shifting point distinguishing the linear root length elongation from power-law development. Root vertical angle in the 40 mm surface soil layer was the largest, but steadily decreased along the soil depth. After 98d, larger root vertical angle appeared in the deep soil layers. PAC revealed a stable root foraging potential in the 0-70d period, which increased rapidly afterwards (70-112d). Root foraging potential, explained by MaxW/MaxD ratio, revealed an enhanced gravitropism in 14d period. No-till post-paddy wheat RLD decreased exponentially in both depth and circular directions, with 90% roots concentrated within the top 20 cm soil layer. RER along soil depth was either positive or negative, depending on specific soil layers and the sampling time.

Effect of different intraorifice barriers on the fracture resistance of roots obturated with Resilon or gutta-percha.

PubMed

Nagas, Emre; Uyanik, Ozgur; Altundasar, Emre; Durmaz, Veli; Cehreli, Zafer C; Vallittu, Pekka K; Lassila, Lippo V J

2010-06-01

This study investigated and compared the root reinforcement potential of 3 different intraorifice barriers (mineral trioxide aggregate [MTA], resin-modified glass ionomer cement [Vitremer], and fiber-reinforced composite [FRC]) placed over root canals obturated with gutta-percha or Resilon. Crowns of 80 extracted human mandibular premolars were sectioned off to obtain 14-mm-long root specimens. After preparation of root canals with nickel-titanium rotary files, the roots were obturated with either the Resilon/Epiphany system or gutta-percha + AH Plus sealer. In both obturation groups, specimens were further subgrouped with respect to the intraorifice barrier material placed after removal of 3-mm coronal portion of the root fillings: (1) MTA, (2) Vitremer, and (3) FRC. The specimens were loaded vertically at 1 mm/min crosshead speed until vertical root fracture occurred. Results were evaluated statistically with two-way analysis of variance and Tukey tests. Fracture resistance of roots was significantly affected by the type of intraorifice barrier (P < .05), but not by the type of obturation system used (P > .05). The use of Vitremer and FRC significantly improved the fracture resistance, whereas MTA did not exhibit any reinforcing effect as an intraorifice barrier. Copyright 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Phenotyping for the dynamics of field wheat root system architecture

PubMed Central

Chen, Xinxin; Ding, Qishuo; Błaszkiewicz, Zbigniew; Sun, Jiuai; Sun, Qian; He, Ruiyin; Li, Yinian

2017-01-01

We investigated a method to quantify field-state wheat RSA in a phenotyping way, depicting the 3D topology of wheat RSA in 14d periods. The phenotyping procedure, proposed for understanding the spatio-temporal variations of root-soil interaction and the RSA dynamics in the field, is realized with a set of indices of mm scale precision, illustrating the gradients of both wheat root angle and elongation rate along soil depth, as well as the foraging potential along the side directions. The 70d was identified as the shifting point distinguishing the linear root length elongation from power-law development. Root vertical angle in the 40 mm surface soil layer was the largest, but steadily decreased along the soil depth. After 98d, larger root vertical angle appeared in the deep soil layers. PAC revealed a stable root foraging potential in the 0–70d period, which increased rapidly afterwards (70–112d). Root foraging potential, explained by MaxW/MaxD ratio, revealed an enhanced gravitropism in 14d period. No-till post-paddy wheat RLD decreased exponentially in both depth and circular directions, with 90% roots concentrated within the top 20 cm soil layer. RER along soil depth was either positive or negative, depending on specific soil layers and the sampling time. PMID:28079107

Proteomic alterations in root tips of Arabidopsis thaliana seedlings under altered gravity conditions

NASA Astrophysics Data System (ADS)

Zheng, H. Q.; Wang, H.

Gravity has a profound influence on plant growth and development Removed the influence of gravitational acceleration by spaceflight caused a wide range of cellular changes in plant Whole seedling that germinated and grown on clinostats showed the absent of gravitropism At the cellular level clinostat treatment has specific effects on plant cells such as induce alterations in cell wall composition increase production of heat-soluble proteins impact on the cellular energy metabolism facilitate a uniform distribution of plastids amyloplasts and increase number and volume of nucleoli A number of recent studies have shown that the exposure of Arabidopsis seedlings and callus cells to gravity stimulation hyper g-forces or clinostat rotation induces alterations in gene expression In our previous study the proteome of the Arabidopsis thaliana callus cells were separated by high resolution two-dimensional electrophoresis 2-DE Image analysis revealed that 80 protein spots showed quantitative and qualitative variations after exposure to clinostat rotation treatment We report here a systematic proteomic approach to investigate the altered gravity responsive proteins in root tip of Arabidopsis thaliana cv Landsberg erecta Three-day-old seedlings were exposed for 12h to a horizontal clinostat rotation H simulated weightlessness altered g-forces by centrifugation 7g hypergravity a vertical clinostat rotation V clinostat control or a stationary control grown conditions Total proteins of roots were extracted

Local root abscisic acid (ABA) accumulation depends on the spatial distribution of soil moisture in potato: implications for ABA signalling under heterogeneous soil drying

PubMed Central

Puértolas, Jaime; Conesa, María R.; Ballester, Carlos; Dodd, Ian C.

2015-01-01

Patterns of root abscisic acid (ABA) accumulation ([ABA]root), root water potential (Ψroot), and root water uptake (RWU), and their impact on xylem sap ABA concentration ([X-ABA]) were measured under vertical partial root-zone drying (VPRD, upper compartment dry, lower compartment wet) and horizontal partial root-zone drying (HPRD, two lateral compartments: one dry, the other wet) of potato (Solanum tuberosum L.). When water was withheld from the dry compartment for 0–10 d, RWU and Ψroot were similarly lower in the dry compartment when soil volumetric water content dropped below 0.22cm3 cm–3 for both spatial distributions of soil moisture. However, [ABA]root increased in response to decreasing Ψroot in the dry compartment only for HPRD, resulting in much higher ABA accumulation than in VPRD. The position of the sampled roots (~4cm closer to the surface in the dry compartment of VPRD than in HPRD) might account for this difference, since older (upper) roots may accumulate less ABA in response to decreased Ψroot than younger (deeper) roots. This would explain differences in root ABA accumulation patterns under vertical and horizontal soil moisture gradients reported in the literature. In our experiment, these differences in root ABA accumulation did not influence [X-ABA], since the RWU fraction (and thus ABA export to shoots) from the dry compartment dramatically decreased simultaneously with any increase in [ABA]root. Thus, HPRD might better trigger a long-distance ABA signal than VPRD under conditions allowing simultaneous high [ABA]root and relatively high RWU fraction. PMID:25547916

Local root abscisic acid (ABA) accumulation depends on the spatial distribution of soil moisture in potato: implications for ABA signalling under heterogeneous soil drying.

PubMed

Puértolas, Jaime; Conesa, María R; Ballester, Carlos; Dodd, Ian C

2015-04-01

Patterns of root abscisic acid (ABA) accumulation ([ABA]root), root water potential (Ψroot), and root water uptake (RWU), and their impact on xylem sap ABA concentration ([X-ABA]) were measured under vertical partial root-zone drying (VPRD, upper compartment dry, lower compartment wet) and horizontal partial root-zone drying (HPRD, two lateral compartments: one dry, the other wet) of potato (Solanum tuberosum L.). When water was withheld from the dry compartment for 0-10 d, RWU and Ψroot were similarly lower in the dry compartment when soil volumetric water content dropped below 0.22cm(3) cm(-3) for both spatial distributions of soil moisture. However, [ABA]root increased in response to decreasing Ψroot in the dry compartment only for HPRD, resulting in much higher ABA accumulation than in VPRD. The position of the sampled roots (~4cm closer to the surface in the dry compartment of VPRD than in HPRD) might account for this difference, since older (upper) roots may accumulate less ABA in response to decreased Ψroot than younger (deeper) roots. This would explain differences in root ABA accumulation patterns under vertical and horizontal soil moisture gradients reported in the literature. In our experiment, these differences in root ABA accumulation did not influence [X-ABA], since the RWU fraction (and thus ABA export to shoots) from the dry compartment dramatically decreased simultaneously with any increase in [ABA]root. Thus, HPRD might better trigger a long-distance ABA signal than VPRD under conditions allowing simultaneous high [ABA]root and relatively high RWU fraction. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Rooting depth distribution and nitrogen acquisition using 15N tracer, Barrow, Alaska, 2013

DOE Office of Scientific and Technical Information (OSTI.GOV)

Colleen Iversen

Permafrost thaw and degradation may lead to altered thickness of the active soil layer and a changing distribution of plant-available nutrients throughout the soil, but little is known about the nutrient acquisition strategies of dominant tundra plant species. We conducted an 15N isotope tracer experiment to assess the vertical distribution of nutrient acquisition among three dominant species representing important plant functional types (PFTs) on the Barrow Environmental Observatory (BEO) in Barrow, Alaska. We found that vertical patterns of root distribution and nutrient acquisition varied among plant species, and that root density may not entirely explain patterns of nutrient acquisition formore » all species.« less

Ice cap melting and low-viscosity crustal root explain the narrow geodetic uplift of the Western Alps

NASA Astrophysics Data System (ADS)

Chéry, J.; Genti, M.; Vernant, P.

2016-04-01

More than 10 years of geodetic measurements demonstrate an uplift rate of 1-3 mm/yr of the high topography region of the Western Alps. By contrast, no significant horizontal motion has been detected. Two uplift mechanisms have been proposed: (1) the isostatic response to denudation responsible for only a fraction of the observed uplift and (2) the rebound induced by the Wurmian ice cap melting which predicts a broader uplifting region than the one evidenced by geodetic observations. Using a numerical model to fit the geodetic data, we show that a crustal viscosity contrast between the foreland and the central part of the Alps, the latter being weaker with a viscosity of 1021 Pa s, is needed. The vertical rates are enhanced if the strong uppermost mantle beneath the Moho is interrupted across the Alps, therefore allowing a weak vertical rheological anomaly over the entire lithosphere.

Do Vertical Gradients in Soil Environmental Conditions Regulate Exudation Rates from Peatland Vegetation?

NASA Astrophysics Data System (ADS)

Proctor, C.; He, Y.

2017-12-01

Deposition of carbon belowground via the root exudation pathway is the net of root-borne efflux and influx processes. For select exudates, root have a remarkable ability to actively recapture lost compounds, suggesting that influx mechanisms regulate exudation. However, roots are not the sole sink for root effluxed carbon. Roots compete with solute sorption and microbial uptake, whom are regulated by a unique set of soil environmental conditions. Peatland soil features stark vertical gradients in their physical, chemical, biological, and hydrological properties, which has downstream implications for the relative competitive ability of each actor in root-soil-microbial interactions. This study developed a single root exudate model using the Barber-Cushman approach to examine the radial accumulation of exudates in simulated peatland soil with vertical gradients. The model simulated efflux, influx, solute diffusion, solute mineralization and solid phase sorption mechanisms as depth dependent on bulk density, porosity, tortuosity, buffer power, temperature, and microbial biomass. Deeper peat soil reduced the porosity that permits solute transport, increased tortuosity which lowered the effective diffusion rate, increased solute-solid sorption, and reduced microbial mineralization of effluxed compounds. Slower mineralization rates were partially juxtaposed by increases in sorption, albeit the net removal of effluxed compounds was lower, leading to a larger amount of exudates to remain in the rhizosphere around deeper roots. Increase in the solid phase, and its subsequent constriction of solute migration, lead to a higher accumulation of effluxed compounds on the rhizoplane, up to 1.23x higher than shallow soil. Subsequently, influx mechanisms captured a larger fraction of effluxed compounds (69.06% at -10cm versus 84.8% at -80 cm), reducing net exudation rates from 0.641 to 0.315 nmol cm-1 hr-1 between -10 and -80cm depths. These results suggest that localized environmental conditions around roots can be a considerable influence on root influx and competition for root exudates. The insights provided by this model help provide a better understanding of exudate regulation in peatlands and the quantity and quality of carbon deposited to the methanogen community.

A highly accurate analytical solution for the surface fields of a short vertical wire antenna lying on a multilayer ground

NASA Astrophysics Data System (ADS)

Parise, M.

2018-01-01

A highly accurate analytical solution is derived to the electromagnetic problem of a short vertical wire antenna located on a stratified ground. The derivation consists of three steps. First, the integration path of the integrals describing the fields of the dipole is deformed and wrapped around the pole singularities and the two vertical branch cuts of the integrands located in the upper half of the complex plane. This allows to decompose the radiated field into its three contributions, namely the above-surface ground wave, the lateral wave, and the trapped surface waves. Next, the square root terms responsible for the branch cuts are extracted from the integrands of the branch-cut integrals. Finally, the extracted square roots are replaced with their rational representations according to Newton's square root algorithm, and residue theorem is applied to give explicit expressions, in series form, for the fields. The rigorous integration procedure and the convergence of square root algorithm ensure that the obtained formulas converge to the exact solution. Numerical simulations are performed to show the validity and robustness of the developed formulation, as well as its advantages in terms of time cost over standard numerical integration procedures.

The use of root plates for nesting sites by Anthophora abrupta (Hymenoptera: Apidae) may be common within forested habitats

Treesearch

Joshua W. Campbell; Cynthia C. Viguiera; Patrick Viguiera; John E. Hartgerink; Cathryn H. Greenberg

2017-01-01

This is the first reported use of root plates by Anthophora abrupta Say (Hymenoptera: Apidae). Previous reported nesting sites were vertical riverbanks and several man-made clay structures. Root plates in forested habitats may be the preferred nesting site for A. abrupta.

An in situ approach to detect tree root ecology: linking ground-penetrating radar imaging to isotope-derived water acquisition zones

PubMed Central

Isaac, Marney E; Anglaaere, Luke C N

2013-01-01

Tree root distribution and activity are determinants of belowground competition. However, studying root response to environmental and management conditions remains logistically challenging. Methodologically, nondestructive in situ tree root ecology analysis has lagged. In this study, we tested a nondestructive approach to determine tree coarse root architecture and function of a perennial tree crop, Theobroma cacao L., at two edaphically contrasting sites (sandstone and phyllite–granite derived soils) in Ghana, West Africa. We detected coarse root vertical distribution using ground-penetrating radar and root activity via soil water acquisition using isotopic matching of δ18O plant and soil signatures. Coarse roots were detected to a depth of 50 cm, however, intraspecifc coarse root vertical distribution was modified by edaphic conditions. Soil δ18O isotopic signature declined with depth, providing conditions for plant–soil δ18O isotopic matching. This pattern held only under sandstone conditions where water acquisition zones were identifiably narrow in the 10–20 cm depth but broader under phyllite–granite conditions, presumably due to resource patchiness. Detected coarse root count by depth and measured fine root density were strongly correlated as were detected coarse root count and identified water acquisition zones, thus validating root detection capability of ground-penetrating radar, but exclusively on sandstone soils. This approach was able to characterize trends between intraspecific root architecture and edaphic-dependent resource availability, however, limited by site conditions. This study successfully demonstrates a new approach for in situ root studies that moves beyond invasive point sampling to nondestructive detection of root architecture and function. We discuss the transfer of such an approach to answer root ecology questions in various tree-based landscapes. PMID:23762519

Active vertical tail buffeting suppression based on macro fiber composites

NASA Astrophysics Data System (ADS)

Zou, Chengzhe; Li, Bin; Liang, Li; Wang, Wei

2016-04-01

Aerodynamic buffet is unsteady airflow exerting forces onto a surface, which can lead to premature fatigue damage of aircraft vertical tail structures, especially for aircrafts with twin vertical tails at high angles of attack. In this work, Macro Fiber Composite (MFC), which can provide strain actuation, was used as the actuator for the buffet-induced vibration control, and the positioning of the MFC patches was led by the strain energy distribution on the vertical tail. Positive Position Feedback (PPF) control algorithm has been widely used for its robustness and simplicity in practice, and consequently it was developed to suppress the buffet responses of first bending and torsional mode of vertical tail. However, its performance is usually attenuated by the phase contributions from non-collocated sensor/actuator configuration and plants. The phase lag between the input and output signals of the control system was identified experimentally, and the phase compensation was considered in the PPF control algorithm. The simulation results of the amplitude frequency of the closed-loop system showed that the buffet response was alleviated notably around the concerned bandwidth. Then the wind tunnel experiment was conducted to verify the effectiveness of MFC actuators and compensated PPF, and the Root Mean Square (RMS) of the acceleration response was reduced 43.4%, 28.4% and 39.5%, respectively, under three different buffeting conditions.

The effect of different posts on fracture strength of roots with vertical fracture and re-attached fragments.

PubMed

Ozcopur, B; Akman, S; Eskitascioglu, G; Belli, S

2010-08-01

The aim of this in vitro study was to test the effect of different post systems on fracture strength of roots with re-attached fragments. Root canals of eighty extracted single-rooted human teeth were instrumented (ProFile) and randomly divided into two groups. The roots in the first group were vertically cracked, and the fragments were re-attached using Super Bond C&B (Sun Medical, Tokya, Japan). The roots in the second group were kept sound. Obturation of the roots was performed with MetaSEAL (Sun Medical) and gutta-percha. Post spaces were prepared, and the roots were restored with one of the followings: UniCore (Ultradent), Everstick (Stick Tech), Ribbond (Ribbond), ParaPost (Coltene/Whaledent) (n = 10). Four mm high build-ups were created (Clearfil DC Bond Core; Kuraray, Tokyo, Japan). Compressive loading of the samples was performed after 24 h (1 mm min(-1)). Mean load necessary to fracture each sample was recorded (Newton) and statistically analysed (One-way anova, t-tests). ParaPost showed the highest fracture strength among the roots with re-attached fragments (P < 0.05). UniCore and ParaPost systems showed similar fracture strength in the sound roots (P > 0.05). Re-attached fragments significantly reduced the fracture strength of roots in UniCore group (P = 0.000). Ribbond post showed mostly repairable fractures. Metal post (ParaPost) showed the highest fracture strength in the roots with re-attached fragments; however, fracture pattern was 41% non-repairable. Re-attached fragments significantly reduced the fracture strength of the roots in UniCore group. Prefabricated posts showed similar fracture strength in the sound roots. Customized post systems EverStick and Ribbond showed mostly repairable failure after loading in sound roots or roots with re-attached fragments.

Correlation Among Soil Enzyme Activities, Root Enzyme Activities, and Contaminant Removal in Two-Stage In Situ Constructed Wetlands Purifying Domestic Wastewater.

PubMed

Ni, Lixiao; Xu, Jiajun; Chu, Xianglin; Li, Shiyin; Wang, Peifang; Li, Yiping; Li, Yong; Zhu, Liang; Wang, Chao

2016-07-01

Two-stage in situ wetlands (two vertical flow constructed wetlands in parallel and a horizontal flow constructed wetland) were constructed for studying domestic wastewater purification and the correlations between contaminant removal and plant and soil enzyme activities. Results indicated the removal efficiency of NH4 (+) and NO3 (-) were significantly correlated with both urease and protease activity, and the removal of total phosphorus was significantly correlated with phosphatase activity. Chemical oxygen demand removal was not correlated with enzyme activity in constructed wetlands. Plant root enzyme (urease, phosphatase, protease and cellulose) activity correlation was apparent with all contaminant removal in the two vertical flow constructed wetlands. However, the correlation between the plant root enzyme activity and contaminant removal was poor in horizontal flow constructed wetlands. Results indicated that plant roots clearly played a role in the removal of contaminants.

Root traits explain observed tundra vegetation nitrogen uptake patterns: Implications for trait-based land models: Tundra N Uptake Model-Data Comparison

DOE PAGES

Zhu, Qing; Iversen, Colleen M.; Riley, William J.; ...

2016-12-23

Ongoing climate warming will likely perturb vertical distributions of nitrogen availability in tundra soils through enhancing nitrogen mineralization and releasing previously inaccessible nitrogen from frozen permafrost soil. But, arctic tundra responses to such changes are uncertain, because of a lack of vertically explicit nitrogen tracer experiments and untested hypotheses of root nitrogen uptake under the stress of microbial competition implemented in land models. We conducted a vertically explicit 15N tracer experiment for three dominant tundra species to quantify plant N uptake profiles. Then we applied a nutrient competition model (N-COM), which is being integrated into the ACME Land Model, tomore » explain the observations. Observations using an 15N tracer showed that plant N uptake profiles were not consistently related to root biomass density profiles, which challenges the prevailing hypothesis that root density always exerts first-order control on N uptake. By considering essential root traits (e.g., biomass distribution and nutrient uptake kinetics) with an appropriate plant-microbe nutrient competition framework, our model reasonably reproduced the observed patterns of plant N uptake. Additionally, we show that previously applied nutrient competition hypotheses in Earth System Land Models fail to explain the diverse plant N uptake profiles we observed. These results cast doubt on current climate-scale model predictions of arctic plant responses to elevated nitrogen supply under a changing climate and highlight the importance of considering essential root traits in large-scale land models. Finally, we provided suggestions and a short synthesis of data availability for future trait-based land model development.« less

Root traits explain observed tundra vegetation nitrogen uptake patterns: Implications for trait-based land models: Tundra N Uptake Model-Data Comparison

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Qing; Iversen, Colleen M.; Riley, William J.

Ongoing climate warming will likely perturb vertical distributions of nitrogen availability in tundra soils through enhancing nitrogen mineralization and releasing previously inaccessible nitrogen from frozen permafrost soil. But, arctic tundra responses to such changes are uncertain, because of a lack of vertically explicit nitrogen tracer experiments and untested hypotheses of root nitrogen uptake under the stress of microbial competition implemented in land models. We conducted a vertically explicit 15N tracer experiment for three dominant tundra species to quantify plant N uptake profiles. Then we applied a nutrient competition model (N-COM), which is being integrated into the ACME Land Model, tomore » explain the observations. Observations using an 15N tracer showed that plant N uptake profiles were not consistently related to root biomass density profiles, which challenges the prevailing hypothesis that root density always exerts first-order control on N uptake. By considering essential root traits (e.g., biomass distribution and nutrient uptake kinetics) with an appropriate plant-microbe nutrient competition framework, our model reasonably reproduced the observed patterns of plant N uptake. Additionally, we show that previously applied nutrient competition hypotheses in Earth System Land Models fail to explain the diverse plant N uptake profiles we observed. These results cast doubt on current climate-scale model predictions of arctic plant responses to elevated nitrogen supply under a changing climate and highlight the importance of considering essential root traits in large-scale land models. Finally, we provided suggestions and a short synthesis of data availability for future trait-based land model development.« less

The influence of gravity and wind on land plant evolution.

PubMed

Niklas, K J

1998-07-01

Aspects of the engineering theory treating the elastic stability of vertical stems and cantilevered leaves supporting their own weight and additional wind-induced forces (drag) are reviewed in light of biomechanical studies of living and fossil terrestrial plant species. The maximum height to which arborescent species can grow before their stems elastically buckle under their own weight is estimated by means of the Euler-Greenhill formula which states that the critical buckling height scales as the 1/3 power of plant tissue-stiffness normalized with respect to tissue bulk density and as the 2/3 power of stem diameter. Data drawn from living plants indicate that progressively taller plant species employ stiffer and lighter-weight plant tissues as the principal stiffening agent in their vertical stems. The elastic stability of plants subjected to high lateral wind-loadings is governed by the drag torque (the product of the drag force and the height above ground at which this force is applied), which cannot exceed the gravitational bending moment (the product of the weight of aerial organs and the lever arm measured at the base of the plant). Data from living plants indicate that the largest arborescent plant species rely on massive trunks and broad, horizontally expansive root crowns to resist drag torques. The drag on the canopies of these plants is also reduced by highly flexible stems and leaves composed of tissues that twist and bend more easily than tissues used to stiffen older, more proximal stems. A brief review of the fossil record suggests that modifications in stem, leaf, and root morphology and anatomy capable of simultaneously coping with self-weight and wind-induced drag forces evolved by Devonian times, suggesting that natural selection acting on the elastic stability of sporophytes occurred early in the history of terrestrial plants.

Characterization of root agravitropism induced by genetic, chemical, and developmental constraints

NASA Technical Reports Server (NTRS)

Moore, R.; Fondren, W. M.; Marcum, H.

1987-01-01

The patterns and rates of organelle redistribution in columella (i.e., putative statocyte) cells of agravitropic agt mutants of Zea mays are not significantly different from those of columella cells in graviresponsive roots. Graviresponsive roots of Z. mays are characterized by a strongly polar movement of 45Ca2+ across the root tip from the upper to the lower side. Horizontally-oriented roots of agt mutants exhibit only a minimal polar transport of 45Ca2+. Exogenously-induced asymmetries of Ca result in curvature of agt roots toward the Ca source. A similar curvature can be induced by a Ca asymmetry in normally nongraviresponsive (i.e., lateral) roots of Phaseolus vulgaris. Similarly, root curvature can be induced by placing the roots perpendicular to an electric field. This electrotropism increased with 1) currents between 8-35 mA, and 2) time between 1-9 hr when the current is constant. Electrotropism is reduced significantly by treating roots with triiodobenzoic acid (TIBA), an inhibitor of auxin transport. These results suggest that 1) if graviperception occurs via the sedimentation of amyloplasts in columella cells, then nongraviresponsive roots apparently sense gravity as do graviresponsive roots, 2) exogenously-induced asymmetries of a gravitropic effector (i.e., Ca) can induce curvature of normally nongraviresponsive roots, 3) the gravity-induced downward movement of exogenously-applied 45Ca2+ across tips of graviresponsive roots does not occur in nongraviresponsive roots, 4) placing roots in an electrical field (i.e., one favoring the movement of ions such as Ca2+) induces root curvature, and 5) electrically-induced curvature is apparently dependent on auxin transport. These results are discussed relative to a model to account for the lack of graviresponsiveness by these roots.

Temperature sensing by primary roots of maize

NASA Technical Reports Server (NTRS)

Poff, K. L.

1990-01-01

Zea mays L. seedlings, grown on agar plates at 26 degrees C, reoriented the original vertical direction of their primary root when exposed to a thermal gradient applied perpendicular to the gravity vector. The magnitude and direction of curvature can not be explained simply by either a temperature or a humidity effect on root elongation. It is concluded that primary roots of maize sense temperature gradients in addition to sensing the gravitational force.

Spatial distribution of Eucalyptus roots in a deep sandy soil in the Congo: relationships with the ability of the stand to take up water and nutrients.

PubMed

Laclau, J P; Arnaud, M; Bouillet, J P; Ranger, J

2001-02-01

Spatial statistical analyses were performed to describe root distribution and changes in soil strength in a mature clonal plantation of Eucalyptus spp. in the Congo. The objective was to analyze spatial variability in root distribution. Relationships between root distribution, soil strength and the water and nutrient uptake by the stand were also investigated. We studied three, 2.35-m-wide, vertical soil profiles perpendicular to the planting row and at various distances from a representative tree. The soil profiles were divided into 25-cm2 grid cells and the number of roots in each of three diameter classes counted in each grid cell. Two profiles were 2-m deep and the third profile was 5-m deep. There was both vertical and horizontal anisotropy in the distribution of fine roots in the three profiles, with root density decreasing sharply with depth and increasing with distance from the stump. Roots were present in areas with high soil strength values (> 6,000 kPa). There was a close relationship between soil water content and soil strength in this sandy soil. Soil strength increased during the dry season mainly because of water uptake by fine roots. There were large areas with low root density, even in the topsoil. Below a depth of 3 m, fine roots were spatially concentrated and most of the soil volume was not explored by roots. This suggests the presence of drainage channels, resulting from the severe hydrophobicity of the upper soil.

Effect of retained fractured instruments on tooth resistance to vertical fracture with or without attempt at removal.

PubMed

Madarati, A A; Qualtrough, A J E; Watts, D C

2010-11-01

To investigate the effect of retained fractured endodontic instruments on root strength and to evaluate the effectiveness of several root filling materials in reinforcing roots that had undergone unsuccessful attempt at removal of fractured instruments. Seventy five mandibular premolar roots were divided into five groups. In group A (control), canals were prepared to a size F5-ProTaper instrument and filled with gutta-percha and TubliSeal sealer fragments. In the experimental groups (B, C, D and E), 4 mm of F5-ProTaper instruments were fractured in the apical one-third of the canal and then treated as follows: in group B, the fragments were left in situ without attempt at removal, and canals were filled with gutta-percha and TubliSeal sealer (GP No Removal). In groups C, D and E, an attempt at removal of the fragment was simulated by preparing a staging platform coronal to the fragment using modified Gates Glidden burs (No 2-5). Canals in group C were filled with gutta-percha and TubliSeal sealer (GP Removal), group D filled with Resilon (Resilon Removal) and group E with mineral trioxide aggregate (MTA Removal). Roots then underwent vertical fracture. Data were analysed using the one-way anova at P<0.05. Roots in the GP Removal group had significantly lower values for mean force for fracture (404.9 N). There was no significant difference between the control group and GP No Removal (765.2 and 707.8, respectively). Resilon Removal and MTA Removal groups (577.3 and 566.6 N) were not significantly different from the GP No Removal group. Leaving fractured instruments in the apical one-third of the canal does not appear to affect the resistance of the root to vertical fracture; Resilon and MTA appear to compensate for root dentine loss that occurred as a consequence of attempts at retrieval of fractured instruments when used as canal filling materials. © 2010 International Endodontic Journal.

Root strength changes after logging in southeast Alaska

Treesearch

R. R. Ziemer; D. N. Swanston

1977-01-01

Abstract - A crucial factor in the stability of steep forested slopes is the role of plant roots in maintaining the shear strength of soil mantles. Roots add strength to the soil by vertically anchoring through the soil mass into failures in the bedrock and by laterally tying the slope together across zones of weakness or instability. Once the covering vegetation is...

Periodontal tissue repair after sealing of the gap in vertical root fracture.

PubMed

Sugaya, Tsutomu; Tomita, Mahito; Motoki, Youji; Zaman, Khurshiduz; Miyaji, Hirofumi; Kawanami, Masamitsu

2017-04-01

The aim of this study was to determine whether sealing of fracture gap using adhesive resin through the root canal can prevent inflammation of periodontal tissue, and resealing the incompletely sealed fracture gap from outside can resolve such inflammation in experimentally created vertical root fractures. Vertical root fractures were created in incisor of beagles. In the experimental group, the fracture gap was sealed through the root canal with adhesive resin. After 5 weeks, sites with the clinical attachment level ≥4 mm were further divided randomly into the poor-replanting group and the poor-untreated group. In the poor-replanting group, the tooth was extracted and replanted after resealing the fracture gap with adhesive resin from the outer surface. Sites with clinical attachment level ≤3 mm after 5 weeks were considered as the satisfactory group. The poor-untreated group and the satisfactory group were subjected to no further treatment. The clinical attachment level was evaluated at baseline and after 2, 5, and 9 weeks. After 9 weeks, histological measurements were made to determine the length of the epithelial downgrowth and the area of alveolar bone resorption. The clinical attachment level and the area of bone resorption were significantly smaller in the poor-replanting group and the satisfactory group than in the poor-untreated group (p < 0.05). The results indicate the possibility that periodontal inflammation along the fracture line can be prevented and improved if the fracture gap is sealed.

Vertical Load Induced with Twisted File Adaptive System during Canal Shaping.

PubMed

Jamleh, Ahmed; Alfouzan, Khalid

2016-12-01

To evaluate the vertical load induced with the Twisted File Adaptive (TFA; SybronEndo, Orange, CA) system during canal shaping of extracted teeth by comparing it with the Twisted File (TF, SybronEndo), ProTaper Next (PTN; Dentsply Maillefer, Ballaigues, Switzerland), and ProTaper Universal (PTU, Dentsply Maillefer) systems. Fifty-two root canals were shaped using the TFA, TF, PTN, or PTU systems (n = 13 for each system). They were shaped gently according to the manufacturers' instructions. During canal shaping, vertical loads were recorded and shown in 2 directions, apically and coronally directed loads. The vertical peak loads of 3 instrumentation stages were used for comparison. The effects of rotary systems on the mean positive and negative peak loads were analyzed statistically using the Kruskal-Wallis and Mann-Whitney tests at a confidence level of 95%. The overall pattern of the instantaneous loads appeared to increase with the use of successive instruments within the system. During canal shaping in all groups, the apically and coronally directed peak loads ranged from 0.84-7.55 N and 2.16-2.79 N, respectively. There were significant differences in both peak loads among the tested systems at each instrumentation stage. TFA had the lowest apically directed peak loads. In terms of coronally directed peak loads, the TFA and TF had a significantly lower amount of loads developed with their instruments than PTN and PTU. The choice of instrument system had an influence on the loads developed during canal shaping. TFA instruments were associated favorably with the lowest values of peak loads followed by TF, PTN, and PTU. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

A comparison of root surface temperatures using different obturation heat sources.

PubMed

Lee, F S; Van Cura, J E; BeGole, E

1998-09-01

This study compared root surface temperatures produced during warm vertical obturation using the System B Heat Source (SB), the Touch 'n Heat device (TH), and a flame-heated carrier (FH). The root canals of 30 maxillary incisor, premolar, and mandibular incisor teeth were prepared; divided into three groups; and obturated using each heat source. A thermocouple placed 2 mm below the cementoenamel junction transferred the temperature rise on the external root surface to a digital thermometer. SB surface temperature rise was < 10 degrees C for all experimental teeth. TH temperature rise in maxillary incisors and premolars was < 10 degrees C; however, > 10 degrees C was observed for mandibular incisors. FH produced a > 10 degrees C surface temperature rise in all experimental teeth. The critical level of root surface heat required to produce irreversible bone damage is believed to be > 10 degrees C. The findings of this study suggest that warm vertical condensation with the SB should not damage supporting periradicular tissues. However, caution should be used with TH and FH on mandibular incisors.

Ultrastructure of pea and cress root statocytes exposed to high gradient magnetic field

NASA Astrophysics Data System (ADS)

Belyavskaya, N. A.; Chernishov, V. I.; Polishchuk, O. V.; Kondrachuk, A. V.

As it was demonstrated by Kuznetsov & Hasenstein (1996) the high gradient magnetic field (HGMF) can produce a ponderomotive force that results in displacements of amyloplasts and causes the root response similar to the graviresponse. It was suggested that the HGMF could allow to imitate the effects of gravity in microgravity and/or change them in laboratory conditions correspondingly, as well as to study statolith-related processes in graviperception. Therefore, the correlation between the direction of the ponderomotive force resulting in statolith displacements and the direction of the HGMF-induced plant curvature can be the serious argument to support this suggestion and needs the detailed ultrastructural analysis. Seeds of dicotyledon Pisum sativum L. cv. Damir-2 and monocotyledon Lepidium sativum L. cv. P896 were soaked and grown in a vertical position on moist filter paper in chambers at room temperature. Tips of primary roots of vertical control, gravistimulated and exposed to HGMF seedlings were fixed for electron microscopy using conventional techniques. At ultrastructural level, we observed no significant changes in the volume of the individual statocytes or amyloplasts, relative volumes of cellular organelles (except vacuoles), number of amyloplasts per statocyte or surface area of endoplasmic reticulum. No consistent contacts between amyloplasts and any cellular structures, including plasma membrane, were revealed at any stage of magneto- and gravistimulation. By 5 min after onset of magnetostimulation, amyloplasts were located along cell wall distant from magnets. In HGMF, the locations of amyloplasts in columella cells were similar to those in horizontally-oriented roots up to 1 h stimulation. In the latter case, there were sometimes cytoplasmic spherical bodies with a dense vesicle-rich cytoplasm in pea statocytes, which were absent in seedlings exposed to HGMF. In cress root statocytes, both gravi- and magnetostimulation were found to cause the appearance of significant amounts of electron-dense granules in the cytoplasm and the nucleus (particularly, in the nucleolus); the effect was most evident in HGMF. Testing the chemical composition of such deposits is going on. The data presented statocyte responses indicate similarity the effects of magneto- and gravistimulation at the ultrastructural level. Thus, the root curvature in HGMF is the plant response to displacement of amyloplasts by ponderomotive force, which can serve as tool for investigation of graviperception mechanism and can provide directional stimulus for plant growth in microgravity. (Financial support by STCU: NN-13R).

Root-tip-mediated inhibition of hydrotropism is accompanied with the suppression of asymmetric expression of auxin-inducible genes in response to moisture gradients in cucumber roots

PubMed Central

Miyabayashi, Sachiko; Sugita, Tomoki; Kobayashi, Akie; Yamazaki, Chiaki; Miyazawa, Yutaka; Kamada, Motoshi; Kasahara, Haruo; Osada, Ikuko; Shimazu, Toru; Fusejima, Yasuo; Higashibata, Akira; Yamazaki, Takashi; Ishioka, Noriaki; Takahashi, Hideyuki

2018-01-01

In cucumber seedlings, gravitropism interferes with hydrotropism, which results in the nearly complete inhibition of hydrotropism under stationary conditions. However, hydrotropic responses are induced when the gravitropic response in the root is nullified by clinorotation. Columella cells in the root cap sense gravity, which induces the gravitropic response. In this study, we found that removing the root tip induced hydrotropism in cucumber roots under stationary conditions. The application of auxin transport inhibitors to cucumber seedlings under stationary conditions suppressed the hydrotropic response induced by the removal of the root tip. To investigate the expression of genes related to hydrotropism in de-tipped cucumber roots, we conducted transcriptome analysis of gene expression by RNA-Seq using seedlings exhibiting hydrotropic and gravitropic responses. Of the 21 and 45 genes asymmetrically expressed during hydrotropic and gravitropic responses, respectively, five genes were identical. Gene ontology (GO) analysis indicated that the category auxin-inducible genes was significantly enriched among genes that were more highly expressed in the concave side of the root than the convex side during hydrotropic or gravitropic responses. Reverse transcription followed by quantitative polymerase chain reaction (RT-qPCR) analysis revealed that root hydrotropism induced under stationary conditions (by removing the root tip) was accompanied by the asymmetric expression of several auxin-inducible genes. However, intact roots did not exhibit the asymmetric expression patterns of auxin-inducible genes under stationary conditions, even in the presence of a moisture gradient. These results suggest that the root tip inhibits hydrotropism by suppressing the induction of asymmetric auxin distribution. Auxin transport and distribution not mediated by the root tip might play a role in hydrotropism in cucumber roots. PMID:29324818

Apical root resorption in maxillary incisors when employing micro-implant and J-hook headgear anchorage: a 4-month radiographic study.

PubMed

Wang, Qingzhu; Chen, Wenjing; Smales, Roger J; Peng, Hui; Hu, Xiaokun; Yin, Lu

2012-10-01

This study evaluated, over a 4-month study period, the amount of apical root resorption occurring in maxillary central incisors following their retraction when employing either micro-implant or J-hook headgear anchorage. The prospective randomised clinical trial was conducted in Orthodontic Clinic, College of Stomatology, China from 2008-2009. Subjects are patients requiring fixed appliances on waiting list (n=20). In female Han Chinese patients aged from 16-26 years, standardized periapical radiographs from 10 randomly assigned patients with maxillary protrusions comprising the micro-implant group, and from 10 similar patients comprising the J-hook headgear group, were assessed for maxillary central incisor apical root resorption. Measurements before and after orthodontic therapy were also obtained from lateral cephalometric radiographs to calculate incisor horizontal retraction and vertical intrusion distances. Estimated retraction force vectors were calculated in horizontal and vertical directions for both treatment groups. Data analysis employed t-tests and the Pearson correlation test, with α=0.05 for statistical significance. The results showed that when compared with the J-hook group, significantly more apical root resorption shortening of the maxillary central incisors was observed in the micro-implant group (1.27 mm difference, 95% CI=0.70-1.84, P<0.001), which was associated with a significantly larger retraction distance (P=0.004) and a smaller vertical force component (P<0.0001). We are led to conclude that continuous activation of the nickel-titanium coil springs used in the micro-implant group resulted in significantly more apical root resorption shortening and maxillary central incisor retraction than when intermittent J-hook retraction was employed. The employment of continuous duration orthodontic forces presents a risk for increased apical root resorption that requires careful radiographic monitoring.

Resistance to vertical fracture of MTA-filled roots.

PubMed

EL-Ma'aita, Ahmad M; Qualtrough, Alison J E; Watts, David C

2014-02-01

To investigate the effect of MTA root canal fillings on the resistance to vertical root fracture (VRF) over different time intervals. Freshly extracted anterior human teeth with single canals and minimal curvatures were decoronated, instrumented to size 50/.05 ProTaper file, irrigated with 1%NaOCl and randomly allocated to one of three groups (n = 36): (i) filled with MTA, (ii) filled with gutta-percha and sealer and (iii) unfilled roots used as a negative control. Each group was subdivided into three subgroups (n = 12) according to the storage time of 48 h, 1 and 6 months at 37°C in synthetic tissue fluid (STF). Following the storage periods, filled roots were mounted in acrylic supports, and the periodontal ligament was simulated using elastomeric impression material. Vertical loading was carried out with a ball-ended steel cylinder fitted on a universal testing machine at 1 mm/min crosshead speed. The maximum force at fracture (F-max) and the fracture mode were recorded for each root. Data were statistically analysed using two-way anova and Bonferroni post hoc tests. The mean F-max was significantly higher in the MTA subgroups after 1 and 6 months compared with all other subgroups. Two modes of fracture were identified: split and comminuted. The mean F-max values recorded with the latter were significantly higher compared with the former (P < 0.001). In all groups, split fracture was the most dominant mode apart from the MTA/1 month and MTA/6 month groups. MTA increases the resistance to VRF of endodontically treated teeth and influences the mode of fracture after 1 and 6 month of storage in STF compared with gutta-percha and sealer. © 2013 John Wiley & Sons A/S.

Understanding the development of roots exposed to contaminants and the potential of plant-associated bacteria for optimization of growth

PubMed Central

Remans, Tony; Thijs, Sofie; Truyens, Sascha; Weyens, Nele; Schellingen, Kerim; Keunen, Els; Gielen, Heidi; Cuypers, Ann; Vangronsveld, Jaco

2012-01-01

Background and Scope Plant responses to the toxic effects of soil contaminants, such as excess metals or organic substances, have been studied mainly at physiological, biochemical and molecular levels, but the influence on root system architecture has received little attention. Nevertheless, the precise position, morphology and extent of roots can influence contaminant uptake. Here, data are discussed that aim to increase the molecular and ecological understanding of the influence of contaminants on root system architecture. Furthermore, the potential of plant-associated bacteria to influence root growth by their growth-promoting and stress-relieving capacities is explored. Methods Root growth parameters of Arabidopsis thaliana seedlings grown in vertical agar plates are quantified. Mutants are used in a reverse genetics approach to identify molecular components underlying quantitative changes in root architecture after exposure to excess cadmium, copper or zinc. Plant-associated bacteria are isolated from contaminated environments, genotypically and phenotypically characterized, and used to test plant root growth improvement in the presence of contaminants. Key Results The molecular determinants of primary root growth inhibition and effects on lateral root density by cadmium were identified. A vertical split-root system revealed local effects of cadmium and copper on root development. However, systemic effects of zinc exposure on root growth reduced both the avoidance of contaminated areas and colonization of non-contaminated areas. The potential for growth promotion and contaminant degradation of plant-associated bacteria was demonstrated by improved root growth of inoculated plants exposed to 2,4-di-nitro-toluene (DNT) or cadmium. Conclusions Knowledge concerning the specific influence of different contaminants on root system architecture and the molecular mechanisms by which this is achieved can be combined with the exploitation of plant-associated bacteria to influence root development and increase plant stress tolerance, which should lead to more optimal root systems for application in phytoremediation or safer biomass production. PMID:22634257

Understanding the development of roots exposed to contaminants and the potential of plant-associated bacteria for optimization of growth.

PubMed

Remans, Tony; Thijs, Sofie; Truyens, Sascha; Weyens, Nele; Schellingen, Kerim; Keunen, Els; Gielen, Heidi; Cuypers, Ann; Vangronsveld, Jaco

2012-07-01

Plant responses to the toxic effects of soil contaminants, such as excess metals or organic substances, have been studied mainly at physiological, biochemical and molecular levels, but the influence on root system architecture has received little attention. Nevertheless, the precise position, morphology and extent of roots can influence contaminant uptake. Here, data are discussed that aim to increase the molecular and ecological understanding of the influence of contaminants on root system architecture. Furthermore, the potential of plant-associated bacteria to influence root growth by their growth-promoting and stress-relieving capacities is explored. Root growth parameters of Arabidopsis thaliana seedlings grown in vertical agar plates are quantified. Mutants are used in a reverse genetics approach to identify molecular components underlying quantitative changes in root architecture after exposure to excess cadmium, copper or zinc. Plant-associated bacteria are isolated from contaminated environments, genotypically and phenotypically characterized, and used to test plant root growth improvement in the presence of contaminants. The molecular determinants of primary root growth inhibition and effects on lateral root density by cadmium were identified. A vertical split-root system revealed local effects of cadmium and copper on root development. However, systemic effects of zinc exposure on root growth reduced both the avoidance of contaminated areas and colonization of non-contaminated areas. The potential for growth promotion and contaminant degradation of plant-associated bacteria was demonstrated by improved root growth of inoculated plants exposed to 2,4-di-nitro-toluene (DNT) or cadmium. Knowledge concerning the specific influence of different contaminants on root system architecture and the molecular mechanisms by which this is achieved can be combined with the exploitation of plant-associated bacteria to influence root development and increase plant stress tolerance, which should lead to more optimal root systems for application in phytoremediation or safer biomass production.

Apical and root canal space sealing abilities of resin and glass ionomer-based root canal obturation systems.

PubMed

Royer, Kinga; Liu, Xue Jun; Zhu, Qiang; Malmstrom, Hans; Ren, Yan-Fang

2013-01-01

To investigate the apical sealing ability of glass ionomer and resin-based root canal obturation systems in comparison to a conventional vertical compaction of warm guttapercha. Forty-five extracted human teeth were randomly assigned into 3 groups of 15 each: a resin-based (EndoRez), a glass ionomer-based (Activ GP), and a conventional gutta-percha plus pulp sealer obturation system (GP/EWT). Apical and root canal space sealing abilities were assessed on five cross-sections 1.0 mm apart starting from the apex. Cross-section images were analysed using a focus-variation 3D scanning microscope and unsealed space was calculated as the percentage of total root canal space occupied by voids and debris. EndoRez had significantly higher rate of apical leakage and deeper dye penetration as compared to GP/EWT and Activ GP. EndoRez group had also more voids and debris (22.5%) in the root canal spaces as compared to GP/EWT (10.5%) and Activ GP (10.8%). Apical leakages occurred not only along the root canal walls, but also along the gutta-percha cones with EndoRez as a result of significant polymerisation shrinkage of the resin sealer. Resin-based EndoRez did not form an adequate apical seal of filled root canals. Glass ionomer-based Activ GP was comparable to a vertical compaction of warm guttapercha plus EWT sealer in sealing root canal spaces.

Effects of plant roots on the hydraulic performance during the clogging process in mesocosm vertical flow constructed wetlands.

PubMed

Hua, G F; Zhao, Z W; Kong, J; Guo, R; Zeng, Y T; Zhao, L F; Zhu, Q D

2014-11-01

The aim of this study was to evaluate the effects of plant roots (Typha angustifolia roots) on the hydraulic performance during the clogging process from the perspective of time and space distributions in mesocosm vertical flow-constructed wetlands with coarse sand matrix. For this purpose, a pair of lab-scale experiments was conducted to compare planted and unplanted systems by measuring the effective porosity and hydraulic conductivity of the substrate within different operation periods. Furthermore, the flow pattern of the clogging process in the planted and unplanted wetland systems were evaluated by their hydraulic performance (e.g., mean residence time, short circuiting, volumetric efficiency, number of continuously stirred tank reactors, and hydraulic efficiency factor) in salt tracer experiments. The results showed that the flow conditions would change in different clogging stages, which indicated that plants played different roles related to time and space. In the early clogging stages, plant roots restricted the flow of water, while in the middle and later clogging stages, especially the later stage, growing roots opened new pore spaces in the substrate. The roots played an important role in affecting the hydraulic performance in the upper layer (0-30 cm) where the sand matrix had a larger root volume fraction. Finally, the causes of the controversy over plant roots' effects on clogging were discussed. The results helped further understand the effects of plant roots on hydraulic performance during the clogging process.

Early Arabidopsis root hair growth stimulation by pathogenic strains of Pseudomonas syringae.

PubMed

Pecenková, Tamara; Janda, Martin; Ortmannová, Jitka; Hajná, Vladimíra; Stehlíková, Zuzana; Žárský, Viktor

2017-09-01

Selected beneficial Pseudomonas spp. strains have the ability to influence root architecture in Arabidopsis thaliana by inhibiting primary root elongation and promoting lateral root and root hair formation. A crucial role for auxin in this long-term (1week), long-distance plant-microbe interaction has been demonstrated. Arabidopsis seedlings were cultivated in vitro on vertical plates and inoculated with pathogenic strains Pseudomonas syringae pv. maculicola (Psm) and P. syringae pv. tomato DC3000 (Pst), as well as Agrobacterium tumefaciens (Atu) and Escherichia coli (Eco). Root hair lengths were measured after 24 and 48h of direct exposure to each bacterial strain. Several Arabidopsis mutants with impaired responses to pathogens, impaired ethylene perception and defects in the exocyst vesicle tethering complex that is involved in secretion were also analysed. Arabidopsis seedling roots infected with Psm or Pst responded similarly to when infected with plant growth-promoting rhizobacteria; root hair growth was stimulated and primary root growth was inhibited. Other plant- and soil-adapted bacteria induced similar root hair responses. The most compromised root hair growth stimulation response was found for the knockout mutants exo70A1 and ein2. The single immune pathways dependent on salicylic acid, jasmonic acid and PAD4 are not directly involved in root hair growth stimulation; however, in the mutual cross-talk with ethylene, they indirectly modify the extent of the stimulation of root hair growth. The Flg22 peptide does not initiate root hair stimulation as intact bacteria do, but pretreatment with Flg22 prior to Psm inoculation abolished root hair growth stimulation in an FLS2 receptor kinase-dependent manner. These early response phenomena are not associated with changes in auxin levels, as monitored with the pDR5::GUS auxin reporter. Early stimulation of root hair growth is an effect of an unidentified component of living plant pathogenic bacteria. The root hair growth response is triggered in the range of hours after bacterial contact with roots and can be modulated by FLS2 signalling. Bacterial stimulation of root hair growth requires functional ethylene signalling and an efficient exocyst-dependent secretory machinery. © The Author 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please email: journals.permissions@oup.com

Local Soils Information Needed to Define the Root Zone in Process Models on the Gulf Coastal Plain

Treesearch

Mary Anne Sword Sayer; Allan E. Tiarks

2002-01-01

We combined published information and our own experimental results from the Gulf Coastal Plain to evaluate how soil aeration and strength interact with loblolly pine root growth. Our results demonstrate that soil aeration and strength differ by soil series and year and are subject to vertical and horizontal spatial variation. Comparison of loblolly pine root phenology...

Maize varieties released in different eras have similar root length density distributions in the soil, which are negatively correlated with local concentrations of soil mineral nitrogen.

PubMed

Ning, Peng; Li, Sa; White, Philip J; Li, Chunjian

2015-01-01

Larger, and deeper, root systems of new maize varieties, compared to older varieties, are thought to have enabled improved acquisition of soil resources and, consequently, greater grain yields. To compare the spatial distributions of the root systems of new and old maize varieties and their relationships with spatial variations in soil concentrations of available nitrogen (N), phosphorus (P) and potassium (K), two years of field experiments were performed using six Chinese maize varieties released in different eras. Vertical distributions of roots, and available N, P and K in the 0-60 cm soil profile were determined in excavated soil monoliths at silking and maturity. The results demonstrated that new maize varieties had larger root dry weight, higher grain yield and greater nutrient accumulation than older varieties. All varieties had similar total root length and vertical root distribution at silking, but newer varieties maintained greater total root length and had more roots in the 30-60 cm soil layers at maturity. The spatial variation of soil mineral N (Nmin) in each soil horizon was larger than that of Olsen-P and ammonium-acetate-extractable K, and was inversely correlated with root length density (RLD), especially in the 0-20 cm soil layer. It was concluded that greater acquisition of mineral nutrients and higher yields of newer varieties were associated with greater total root length at maturity. The negative relationship between RLD and soil Nmin at harvest for all varieties suggests the importance of the spatial distribution of the root system for N uptake by maize.

Maize Varieties Released in Different Eras Have Similar Root Length Density Distributions in the Soil, Which Are Negatively Correlated with Local Concentrations of Soil Mineral Nitrogen

PubMed Central

Ning, Peng; Li, Sa; White, Philip J.; Li, Chunjian

2015-01-01

Larger, and deeper, root systems of new maize varieties, compared to older varieties, are thought to have enabled improved acquisition of soil resources and, consequently, greater grain yields. To compare the spatial distributions of the root systems of new and old maize varieties and their relationships with spatial variations in soil concentrations of available nitrogen (N), phosphorus (P) and potassium (K), two years of field experiments were performed using six Chinese maize varieties released in different eras. Vertical distributions of roots, and available N, P and K in the 0–60 cm soil profile were determined in excavated soil monoliths at silking and maturity. The results demonstrated that new maize varieties had larger root dry weight, higher grain yield and greater nutrient accumulation than older varieties. All varieties had similar total root length and vertical root distribution at silking, but newer varieties maintained greater total root length and had more roots in the 30–60 cm soil layers at maturity. The spatial variation of soil mineral N (Nmin) in each soil horizon was larger than that of Olsen-P and ammonium-acetate-extractable K, and was inversely correlated with root length density (RLD), especially in the 0–20 cm soil layer. It was concluded that greater acquisition of mineral nutrients and higher yields of newer varieties were associated with greater total root length at maturity. The negative relationship between RLD and soil Nmin at harvest for all varieties suggests the importance of the spatial distribution of the root system for N uptake by maize. PMID:25799291

Spectral combination of spherical gravitational curvature boundary-value problems

NASA Astrophysics Data System (ADS)

PitoÅák, Martin; Eshagh, Mehdi; Šprlák, Michal; Tenzer, Robert; Novák, Pavel

2018-04-01

Four solutions of the spherical gravitational curvature boundary-value problems can be exploited for the determination of the Earth's gravitational potential. In this article we discuss the combination of simulated satellite gravitational curvatures, i.e., components of the third-order gravitational tensor, by merging these solutions using the spectral combination method. For this purpose, integral estimators of biased- and unbiased-types are derived. In numerical studies, we investigate the performance of the developed mathematical models for the gravitational field modelling in the area of Central Europe based on simulated satellite measurements. Firstly, we verify the correctness of the integral estimators for the spectral downward continuation by a closed-loop test. Estimated errors of the combined solution are about eight orders smaller than those from the individual solutions. Secondly, we perform a numerical experiment by considering the Gaussian noise with the standard deviation of 6.5× 10-17 m-1s-2 in the input data at the satellite altitude of 250 km above the mean Earth sphere. This value of standard deviation is equivalent to a signal-to-noise ratio of 10. Superior results with respect to the global geopotential model TIM-r5 are obtained by the spectral downward continuation of the vertical-vertical-vertical component with the standard deviation of 2.104 m2s-2, but the root mean square error is the largest and reaches 9.734 m2s-2. Using the spectral combination of all gravitational curvatures the root mean square error is more than 400 times smaller but the standard deviation reaches 17.234 m2s-2. The combination of more components decreases the root mean square error of the corresponding solutions while the standard deviations of the combined solutions do not improve as compared to the solution from the vertical-vertical-vertical component. The presented method represents a weight mean in the spectral domain that minimizes the root mean square error of the combined solutions and improves standard deviation of the solution based only on the least accurate components.

Root coverage with cultured gingival dermal substitute composed of gingival fibroblasts and matrix: a case series.

PubMed

Murata, Masashi; Okuda, Kazuhiro; Momose, Manabu; Kubo, Kentarou; Kuroyanagi, Yoshimitsu; Wolff, Larry F

2008-10-01

Cultured gingival dermal substitute (CGDS), composed of gingival fibroblasts and matrix and fabricated using tissue-engineering techniques, has been used for root coverage procedures. Fourteen sites from four patients with > or = 2 mm of Miller Class I or II facial gingival tissue recession were treated. The autologous CGDS sheet, prepared prior to surgical treatment, was grafted over the teeth with gingival recession and then covered with a coronally positioned flap. Vertical and horizontal recession was measured at baseline (prior to the surgical procedure) and 13 to 40 weeks (average: 30.7 +/- 9.6 weeks) after surgery. The average vertical and horizontal root coverage after surgery was 79.1% +/- 25.7% and 75.2% +/- 31.4%, respectively. Moreover, there was a significant increase of keratinized and attached gingival tissue at the final clinical evaluation compared with preoperative measurements (P < .05). These results demonstrate CGDS as a promising grafting material for use with root coverage procedures in periodontal therapy.

Change in corneal aberrations after cataract surgery with 2 types of aspherical intraocular lenses.

PubMed

Marcos, Susana; Rosales, Patricia; Llorente, Lourdes; Jiménez-Alfaro, Ignacio

2007-02-01

To study the effect of cataract surgery through 3.2 mm superior incisions on corneal aberrations with 2 types of monofocal intraocular lenses (IOLs) with an aspherical design. Instituto de Optica, Consejo Superior de Investigaciones Científicas, and Fundación Jiménez Díaz, Madrid, Spain. Corneal topography of 43 eyes was obtained before and after small corneal incision cataract surgery. Twenty-two eyes had implantation of a Tecnis Z9000 silicone IOL (Advanced Medical Optics) and 21 had implantation of an AcrySof IQ SN60WF acrylic IOL (Alcon Research Labs) using the recommended injector for each IOL type. The intended incision size (3.2 mm) was similar in the 2 groups. Corneal aberrations were estimated using custom-developed algorithms (based on ray tracing) for 10.0 mm and 5.0 mm pupils. Comparisons between preoperative and postoperative measurements and across the groups were made for individual Zernike terms and root-mean-square (RMS) wavefront error. The RMS (excluding tilt and defocus) did not change in the AcrySof IQ group and increased significantly in the Tecnis group with the 10.0 mm and 5.0 mm pupil diameters. Spherical aberration and coma-like terms did not change significantly; however, vertical astigmatism, vertical trefoil, and vertical tetrafoil changed significantly with surgery with the 10.0 mm and 5.0 mm pupil diameters (P<.0005). The induced wave aberration pattern for 3rd- and higher-order aberrations consistently showed a superior lobe, resulting from a combination of positive vertical trefoil (Z(3)(-3)) and negative tetrafoil (Z(4)(4)). The mean vertical astigmatism increased by 2.47 microm +/- 1.49 (SD) and 1.74 +/- 1.44 microm, vertical trefoil increased by 1.81 +/- 1.19 microm and 1.20 +/- 1.34 microm, and tetrafoil increased by -1.10 +/- 0.78 microm and -0.89 +/- 0.68 microm in the Tecnis group and AcrySof IQ group, respectively. There were no significant differences between the corneal aberrations in the 2 postoperative groups, although there was a tendency toward more terms or orders changing statistically significantly in the Tecnis group, which had slightly higher amounts of induced aberrations. Cataract surgery with a small superior incision induced consistent and significant changes in several corneal Zernike terms (vertical astigmatism, trefoil, and tetrafoil), resulting in a significantly increased overall corneal RMS wavefront error. These results can be used to improve predictions of optical performance with new IOL designs using computer eye models and identify the potentially different impact of incision strategies on cataract surgery.

Unraveling the hydrodynamics of split root water uptake experiments using CT scanned root architectures and three dimensional flow simulations

PubMed Central

Koebernick, Nicolai; Huber, Katrin; Kerkhofs, Elien; Vanderborght, Jan; Javaux, Mathieu; Vereecken, Harry; Vetterlein, Doris

2015-01-01

Split root experiments have the potential to disentangle water transport in roots and soil, enabling the investigation of the water uptake pattern of a root system. Interpretation of the experimental data assumes that water flow between the split soil compartments does not occur. Another approach to investigate root water uptake is by numerical simulations combining soil and root water flow depending on the parameterization and description of the root system. Our aim is to demonstrate the synergisms that emerge from combining split root experiments with simulations. We show how growing root architectures derived from temporally repeated X-ray CT scanning can be implemented in numerical soil-plant models. Faba beans were grown with and without split layers and exposed to a single drought period during which plant and soil water status were measured. Root architectures were reconstructed from CT scans and used in the model R-SWMS (root-soil water movement and solute transport) to simulate water potentials in soil and roots in 3D as well as water uptake by growing roots in different depths. CT scans revealed that root development was considerably lower with split layers compared to without. This coincided with a reduction of transpiration, stomatal conductance and shoot growth. Simulated predawn water potentials were lower in the presence of split layers. Simulations showed that this was related to an increased resistance to vertical water flow in the soil by the split layers. Comparison between measured and simulated soil water potentials proved that the split layers were not perfectly isolating and that redistribution of water from the lower, wetter compartments to the drier upper compartments took place, thus water losses were not equal to the root water uptake from those compartments. Still, the layers increased the resistance to vertical flow which resulted in lower simulated collar water potentials that led to reduced stomatal conductance and growth. PMID:26074935

Arsenic- and selenium-induced changes in spectral reflectance and morphology of soybean plants

USGS Publications Warehouse

Milton, N.M.; Ager, C.M.; Eiswerth, B.A.; Power, M.S.

1989-01-01

Soybean (Glycine max) plants were grown in hydroponic solutions treated with high concentrations of either arsenic or selenium. Spectral reflectance changes in arsenic-dosed plants included a shift to shorter wavelengths in the long-wavelength edge of the chlorophyll absorption band centered at 680 nm (the red edge) and higher reflectance in the 550-650 nm region. These results are consistent with vegetation reflectance anomalies observed in previous greenhouse experiments and in airborne radiometer studies. The selenium-dosed plants contrast, exhibited a shift to longer wavelengths of the red edge and lower reflectance between 550 nm and 650 wh when compared with control plants. Morphological effects of arsenic uptake included lower overall biomass, stunted and discolored roots, and smaller leaves oriented more vertically than leaves of control plants. Selenium-dosed plants also displayed morphological changes, but root and leaf biomass were less affected than were those of arsenic-dosed plants when compared to control plants. ?? 1989.

Hydrologic control on the root growth of Salix cuttings at the laboratory scale

NASA Astrophysics Data System (ADS)

Bau', Valentina; Calliari, Baptiste; Perona, Paolo

2017-04-01

Riparian plant roots contribute to the ecosystem functioning and, to a certain extent, also directly affect fluvial morphodynamics, e.g. by influencing sediment transport via mechanical stabilization and trapping. There is much both scientific and engineering interest in understanding the complex interactions among riparian vegetation and river processes. For example, to investigate plant resilience to uprooting by flow, one should quantify the probability that riparian plants may be uprooted during specific flooding event. Laboratory flume experiments are of some help to this regard, but are often limited to use grass (e.g., Avena and Medicago sativa) as vegetation replicate with a number of limitations due to fundamental scaling problems. Hence, the use of small-scale real plants grown undisturbed in the actual sediment and within a reasonable time frame would be particularly helpful to obtain more realistic flume experiments. The aim of this work is to develop and tune an experimental technique to control the growth of the root vertical density distribution of small-scale Salix cuttings of different sizes and lengths. This is obtained by controlling the position of the saturated water table in the sedimentary bed according to the sediment size distribution and the cutting length. Measurements in the rhizosphere are performed by scanning and analysing the whole below-ground biomass by means of the root analysis software WinRhizo, from which root morphology statistics and the empirical vertical density distribution are obtained. The model of Tron et al. (2015) for the vertical density distribution of the below-ground biomass is used to show that experimental conditions that allow to develop the desired root density distribution can be fairly well predicted. This augments enormously the flexibility and the applicability of the proposed methodology in view of using such plants for novel flow erosion experiments. Tron, S., Perona, P., Gorla, L., Schwarz, M., Laio, F., and L. Ridolfi (2015). The signature of randomness in riparian plant root distributions. Geophys. Res. Letts., 42, 7098-7106

Microcomputed tomography analysis of mesiobuccal orifices and major apical foramen in first maxillary molars.

PubMed

Spagnuolo, Gianrico; Ametrano, Gianluca; D'Antò, Vincenzo; Formisano, Anna; Simeone, Michele; Riccitiello, Francesco; Amato, Massimo; Rengo, Sandro

2012-01-01

Aim of the study was to determined by microcomputed tomography (µCT) the horizontal distance between the main (MB1) and the second mesiobuccal canal (MB2) orifices, the vertical distance between the MB1 and MB2 orifices planes, and the distance between the anatomic apex and major apical foramen (AF). Furthermore, we characterized the entire internal and external anatomy of the MB, distalbuccal (DB) and palatal (P) maxillary first molars roots. Twenty-two intact extracted first maxillary molars were scanned by X-ray computed transaxial µCT and then 2D and 3D images were processed and analyzed. The results showed that 77.27% of the mesiobuccal (MB) roots presented a second MB canal, and 29.41% of the MB2 were independent from the MB1 canals. In 15 teeth, there were three root canal orifices on the chamber floor, and 10 of these teeth presented MB2 canals. The mean vertical distance between the MB1 and MB2 planes was 1.68 ± 0.83 mm. Seven teeth had four orifices. The mean horizontal interorificial distance between the MB1 and MB2 orifices was 1.21 ± 0.5 mm. Accessory canals were observed in 33.33% of the roots, loops in 6.06%, while isthmuses were found in 15 of the 22 MB roots. Of the total roots, 74.24% presented one foramen, while all of the roots showed a major apical foramen that was not coincident with the anatomic apex. Our µCT analysis provided interesting features on the horizontal and vertical distance between the MB1 and MB2 orifices and on the distance of AF and anatomic apex. These results have an important clinical value because might support the endodontist in the recruitment, negotiation and obturation of maxillary first molar canal system.

Microcomputed Tomography Analysis of Mesiobuccal Orifices and Major Apical Foramen in First Maxillary Molars

PubMed Central

Spagnuolo, Gianrico; Ametrano, Gianluca; D’Antò, Vincenzo; Formisano, Anna; Simeone, Michele; Riccitiello, Francesco; Amato, Massimo; Rengo, Sandro

2012-01-01

Objective: Aim of the study was to determined by microcomputed tomography (µCT) the horizontal distance between the main (MB1) and the second mesiobuccal canal (MB2) orifices, the vertical distance between the MB1 and MB2 orifices planes, and the distance between the anatomic apex and major apical foramen (AF). Furthermore, we characterized the entire internal and external anatomy of the MB, distalbuccal (DB) and palatal (P) maxillary first molars roots. Materials and Methods: Twenty-two intact extracted first maxillary molars were scanned by X-ray computed transaxial µCT and then 2D and 3D images were processed and analyzed. Results: The results showed that 77.27% of the mesiobuccal (MB) roots presented a second MB canal, and 29.41% of the MB2 were independent from the MB1 canals. In 15 teeth, there were three root canal orifices on the chamber floor, and 10 of these teeth presented MB2 canals. The mean vertical distance between the MB1 and MB2 planes was 1.68 ± 0.83 mm. Seven teeth had four orifices. The mean horizontal interorificial distance between the MB1 and MB2 orifices was 1.21 ± 0.5 mm. Accessory canals were observed in 33.33% of the roots, loops in 6.06%, while isthmuses were found in 15 of the 22 MB roots. Of the total roots, 74.24% presented one foramen, while all of the roots showed a major apical foramen that was not coincident with the anatomic apex. Conclusions: Our µCT analysis provided interesting features on the horizontal and vertical distance between the MB1 and MB2 orifices and on the distance of AF and anatomic apex. Clinical Relevance: These results have an important clinical value because might support the endodontist in the recruitment, negotiation and obturation of maxillary first molar canal system. PMID:22905069

Trampling, defoliation and physiological integration affect growth, morphological and mechanical properties of a root-suckering clonal tree.

PubMed

Xu, Liang; Yu, Fei-Hai; van Drunen, Elles; Schieving, Feike; Dong, Ming; Anten, Niels P R

2012-04-01

Grazing is a complex process involving the simultaneous occurrence of both trampling and defoliation. Clonal plants are a common feature of heavily grazed ecosystems where large herbivores inflict the simultaneous pressures of trampling and defoliation on the vegetation. We test the hypothesis that physiological integration (resource sharing between interconnected ramets) may help plants to deal with the interactive effects of trampling and defoliation. In a field study, small and large ramets of the root-suckering clonal tree Populus simonii were subjected to two levels of trampling and defoliation, while connected or disconnected to other ramets. Plant responses were quantified via survival, growth, morphological and stem mechanical traits. Disconnection and trampling increased mortality, especially in small ramets. Trampling increased stem length, basal diameter, fibrous root mass, stem stiffness and resistance to deflection in connected ramets, but decreased them in disconnected ones. Trampling decreased vertical height more in disconnected than in connected ramets, and reduced stem mass in disconnected ramets but not in connected ramets. Defoliation reduced basal diameter, leaf mass, stem mass and leaf area ratio, but did not interact with trampling or disconnection. Although clonal integration did not influence defoliation response, it did alleviate the effects of trampling. We suggest that by facilitating resource transport between ramets, clonal integration compensates for trampling-induced damage to fine roots.

Root depth and morphology in response to soil drought: comparing ecological groups along the secondary succession in a tropical dry forest.

PubMed

Paz, Horacio; Pineda-García, Fernando; Pinzón-Pérez, Luisa F

2015-10-01

Root growth and morphology may play a core role in species-niche partitioning in highly diverse communities, especially along gradients of drought risk, such as that created along the secondary succession of tropical dry forests. We experimentally tested whether root foraging capacity, especially at depth, decreases from early successional species to old-growth forest species. We also tested for a trade-off between two mechanisms for delaying desiccation, the capacity to forage deeper in the soil and the capacity to store water in tissues, and explored whether successional groups separate along such a trade-off. We examined the growth and morphology of roots in response to a controlled-vertical gradient of soil water, among seedlings of 23 woody species dominant along the secondary succession in a tropical dry forest of Mexico. As predicted, successional species developed deeper and longer root systems than old-growth forest species in response to soil drought. In addition, shallow root systems were associated with high plant water storage and high water content per unit of tissue in stems and roots, while deep roots exhibited the opposite traits, suggesting a trade-off between the capacities for vertical foraging and water storage. Our results suggest that an increased capacity of roots to forage deeper for water is a trait that enables successional species to establish under the warm-dry conditions of the secondary succession, while shallow roots, associated with a higher water storage capacity, are restricted to the old-growth forest. Overall, we found evidence that the root depth-water storage trade-off may constrain tree species distribution along secondary succession.

In vitro study of root fracture treated by CO2 laser and DP-bioactive glass paste.

PubMed

Wang, Yin-Lin; Lee, Bor-Shiunn; Tseng, Ching-Li; Lin, Feng-Huei; Lin, Chun-Pin

2008-01-01

An ideal material has yet to be discovered that can successfully treat vertical root fracture. Therefore, the purpose of this study was to use a continuous-wave CO2 laser of medium-energy density to fuse DP-bioactive glass paste (DPGP) to vertical root fracture. The DP-bioglass powder was based on a Na2O-CaO-SiO2-P2O5 system and it was mixed with phosphoric acid (65% concentration) with a powder/liquid ratio of 2 g/4 mL to form DPGP. The interaction of DPGP and dentin was analyzed by means of X-ray diffractometer (XRD) and differential thermal analysis/thermogravimetric analysis (DTA/TGA). Root fracture line was filled with DPGP followed by CO2 laser irradiation and the result was examined by scanning electron microscopy (SEM). The main crystal phase of DPGP was monocalcium phosphate monohydrate (Ca(H2PO4)2.H2O) and the phase transformed to dicalcium phosphate dihydrate (CaHPO4.2H2O) after mixing DPGP with dentin powder (DPG-D). Additionally, gamma-Ca2P2O7 and beta-Ca2P2O7 were identified when DPG-D was lased by CO2 laser. The reaction temperature was between 500 degrees C and 1100 degrees C. SEM results demonstrated that the fracture line was effectively sealed by DPGP. The chemical reaction of DPGP and dentin indicated that DPGP combined with CO2 laser is a potential regimen for the treatment of vertical root fracture.

Influence of different final irrigation regimens and various endodontic filling materials on vertical root fracture resistance.

PubMed

Sungur, D D; Altundasar, E; Uzunoglu, E; Yilmaz, Z

2016-01-01

The aim of this study was to evaluate the influence of different endodontic materials and final irrigation regimens on vertical root fracture (VRF) resistance. Eighty human teeth were prepared then assigned into two groups (n = 40) according to the final irrigations. G1: 5 mL, 5.25% sodium hypochlorite (NaOCl), G2: 5 mL, 2% chlorhexidine gluconate (CHX). Each group was assigned into four subgroups according to the obturation system used (n = 10): A: iRoot SP/single gutta-percha cone (SGP), B: Only iRoot SP, C: Mineral trioxide aggregate (MTA)-Fillapex/SGP, D: AH26/SGP. The specimens were embedded in acrylic molds and subjected to compressive loading at a rate of 1 mm min until VRF occurred. Data were analyzed via three-way ANOVA tests. The statistically significant difference was found among groups (P < 0.05). The G1A and G1B and G1D revealed significantly higher-VRF values than G1C (P = 0.023). The roots filled with MTA-Fillapex revealed lower-VRF values than the other subgroups (P < 0.05). Groups irrigated with NaOCl had significantly lower-VRF values than the groups irrigated with CHX (P < 0.05). Final irrigation regimens could alter VRF resistance of root canals filled with different obturation technique and root canal sealers.

Coupling fine-scale root and canopy structure using ground-based remote sensing

DOE PAGES

Hardiman, Brady S.; Gough, Christopher M.; Butnor, John R.; ...

2017-02-21

Ecosystem physical structure, defined by the quantity and spatial distribution of biomass, influences a range of ecosystem functions. Remote sensing tools permit the non-destructive characterization of canopy and root features, potentially providing opportunities to link above- and belowground structure at fine spatial resolution in functionally meaningful ways. To test this possibility, we employed ground-based portable canopy LiDAR (PCL) and ground penetrating radar (GPR) along co-located transects in forested sites spanning multiple stages of ecosystem development and, consequently, of structural complexity. We examined canopy and root structural data for coherence (i.e., correlation in the frequency of spatial variation) at multiple spatialmore » scales 10 m within each site using wavelet analysis. Forest sites varied substantially in vertical canopy and root structure, with leaf area index and root mass more becoming even vertically as forests aged. In all sites, above- and belowground structure, characterized as mean maximum canopy height and root mass, exhibited significant coherence at a scale of 3.5–4 m, and results suggest that the scale of coherence may increase with stand age. Our findings demonstrate that canopy and root structure are linked at characteristic spatial scales, which provides the basis to optimize scales of observation. Lastly, our study highlights the potential, and limitations, for fusing LiDAR and radar technologies to quantitatively couple above- and belowground ecosystem structure.« less

Coupling fine-scale root and canopy structure using ground-based remote sensing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hardiman, Brady S.; Gough, Christopher M.; Butnor, John R.

Ecosystem physical structure, defined by the quantity and spatial distribution of biomass, influences a range of ecosystem functions. Remote sensing tools permit the non-destructive characterization of canopy and root features, potentially providing opportunities to link above- and belowground structure at fine spatial resolution in functionally meaningful ways. To test this possibility, we employed ground-based portable canopy LiDAR (PCL) and ground penetrating radar (GPR) along co-located transects in forested sites spanning multiple stages of ecosystem development and, consequently, of structural complexity. We examined canopy and root structural data for coherence (i.e., correlation in the frequency of spatial variation) at multiple spatialmore » scales 10 m within each site using wavelet analysis. Forest sites varied substantially in vertical canopy and root structure, with leaf area index and root mass more becoming even vertically as forests aged. In all sites, above- and belowground structure, characterized as mean maximum canopy height and root mass, exhibited significant coherence at a scale of 3.5–4 m, and results suggest that the scale of coherence may increase with stand age. Our findings demonstrate that canopy and root structure are linked at characteristic spatial scales, which provides the basis to optimize scales of observation. Lastly, our study highlights the potential, and limitations, for fusing LiDAR and radar technologies to quantitatively couple above- and belowground ecosystem structure.« less

UV-B Radiation Induces Root Bending Through the Flavonoid-Mediated Auxin Pathway in Arabidopsis.

PubMed

Wan, Jinpeng; Zhang, Ping; Wang, Ruling; Sun, Liangliang; Wang, Wenying; Zhou, Huakun; Xu, Jin

2018-01-01

Ultraviolet (UV)-B radiation-induced root bending has been reported; however, the underlying mechanisms largely remain unclear. Here, we investigate whether and how auxin and flavonoids are involved in UV-B radiation-induced root bending in Arabidopsis using physiological, pharmacological, and genetic approaches. UV-B radiation modulated the direction of root growth by decreasing IAA biosynthesis and affecting auxin distribution in the root tips, where reduced auxin accumulation and asymmetric auxin distribution were observed. UV-B radiation increased the distribution of auxin on the nonradiated side of the root tips, promoting growth and causing root bending. Further analysis indicated that UV-B induced an asymmetric accumulation of flavonoids; this pathway is involved in modulating the accumulation and asymmetric distribution of auxin in root tips and the subsequent redirection of root growth by altering the distribution of auxin carriers in response to UV-B radiation. Taken together, our results indicate that UV-B radiation-induced root bending occurred through a flavonoid-mediated phototropic response to UV-B radiation.

UV-B Radiation Induces Root Bending Through the Flavonoid-Mediated Auxin Pathway in Arabidopsis

PubMed Central

Wan, Jinpeng; Zhang, Ping; Wang, Ruling; Sun, Liangliang; Wang, Wenying; Zhou, Huakun; Xu, Jin

2018-01-01

Ultraviolet (UV)-B radiation-induced root bending has been reported; however, the underlying mechanisms largely remain unclear. Here, we investigate whether and how auxin and flavonoids are involved in UV-B radiation-induced root bending in Arabidopsis using physiological, pharmacological, and genetic approaches. UV-B radiation modulated the direction of root growth by decreasing IAA biosynthesis and affecting auxin distribution in the root tips, where reduced auxin accumulation and asymmetric auxin distribution were observed. UV-B radiation increased the distribution of auxin on the nonradiated side of the root tips, promoting growth and causing root bending. Further analysis indicated that UV-B induced an asymmetric accumulation of flavonoids; this pathway is involved in modulating the accumulation and asymmetric distribution of auxin in root tips and the subsequent redirection of root growth by altering the distribution of auxin carriers in response to UV-B radiation. Taken together, our results indicate that UV-B radiation-induced root bending occurred through a flavonoid-mediated phototropic response to UV-B radiation. PMID:29868074

Vertical-plane pendulum absorbers for minimizing helicopter vibratory loads

NASA Technical Reports Server (NTRS)

Amer, K. B.; Neff, J. R.

1974-01-01

The use of pendulum dynamic absorbers mounted on the blade root and operating in the vertical plane to minimize helicopter vibratory loads was discussed. A qualitative description was given of the concept of the dynamic absorbers and some results of analytical studies showing the degree of reduction in vibratory loads attainable are presented. Operational experience of vertical plane dynamic absorbers on the OH-6A helicopter is also discussed.

Biophysical controls on accretion and elevation change in Caribbean mangrove ecosystems

USGS Publications Warehouse

McKee, K.L.

2011-01-01

Habitat stability of coastal ecosystems, such as marshes and mangroves, depends on maintenance of soil elevations relative to sea level. Many such systems are characterized by limited mineral sedimentation and/or rapid subsidence and are consequently dependent upon accumulation of organic matter to maintain elevations. However, little field information exists regarding the contribution of specific biological processes to vertical accretion and elevation change. This study used biogenic mangrove systems in carbonate settings in Belize (BZ) and southwest Florida (FL) to examine biophysical controls on elevation change. Rates of elevation change, vertical accretion, benthic mat formation, and belowground root accumulation were measured in fringe, basin, scrub, and dwarf forest types plus a restored forest. Elevation change rates (mm yr-1) measured with Surface Elevation Tables varied widely: BZ-Dwarf (-3.7), BZ-Scrub (-1.1), FL-Fringe (0.6), FL-Basin (2.1), BZ-Fringe (4.1), and FL-Restored (9.9). Root mass accumulation varied across sites (82-739 g m-2 yr-1) and was positively correlated with elevation change. Root volumetric contribution to vertical change (mm yr-1) was lowest in BZ-Dwarf (1.2) and FL-Fringe (2.4), intermediate in FL-Basin (4.1) and BZ-Scrub (4.3), and highest in BZ-Fringe (8.8) and FL-Restored (11.8) sites. Surface growth of turf-forming algae, microbial mats, or accumulation of leaf litter and detritus also made significant contributions to vertical accretion. Turf algal mats in fringe and scrub forests accreted faster (2.7 mm yr-1) than leaf litter mats in basin forests (1.9 mm yr-1), but similarly to microbial mats in dwarf forests (2.1 mm yr-1). Surface accretion of mineral material accounted for only 0.2-3.3% of total vertical change. Those sites with high root contributions and/or rapid growth of living mats exhibited an elevation surplus (+2 to +8 mm yr-1), whereas those with low root inputs and low (or non-living) mat accumulation showed an elevation deficit (-1 to -5.7 mm yr-1). This study indicates that biotic processes of root production and benthic mat formation are important controls on accretion and elevation change in mangrove ecosystems common to the Caribbean Region. Quantification of specific biological controls on elevation provides better insight into how sustainability of such systems might be influenced by global (e.g., climate, atmospheric CO2) and local (e.g., nutrients, disturbance) factors affecting organic matter accumulation, in addition to relative sea-level rise. ?? 2010.

Biophysical controls on accretion and elevation change in Caribbean mangrove ecosystems

NASA Astrophysics Data System (ADS)

McKee, Karen L.

2011-03-01

Habitat stability of coastal ecosystems, such as marshes and mangroves, depends on maintenance of soil elevations relative to sea level. Many such systems are characterized by limited mineral sedimentation and/or rapid subsidence and are consequently dependent upon accumulation of organic matter to maintain elevations. However, little field information exists regarding the contribution of specific biological processes to vertical accretion and elevation change. This study used biogenic mangrove systems in carbonate settings in Belize (BZ) and southwest Florida (FL) to examine biophysical controls on elevation change. Rates of elevation change, vertical accretion, benthic mat formation, and belowground root accumulation were measured in fringe, basin, scrub, and dwarf forest types plus a restored forest. Elevation change rates (mm yr -1) measured with Surface Elevation Tables varied widely: BZ-Dwarf (-3.7), BZ-Scrub (-1.1), FL-Fringe (0.6), FL-Basin (2.1), BZ-Fringe (4.1), and FL-Restored (9.9). Root mass accumulation varied across sites (82-739 g m -2 yr -1) and was positively correlated with elevation change. Root volumetric contribution to vertical change (mm yr -1) was lowest in BZ-Dwarf (1.2) and FL-Fringe (2.4), intermediate in FL-Basin (4.1) and BZ-Scrub (4.3), and highest in BZ-Fringe (8.8) and FL-Restored (11.8) sites. Surface growth of turf-forming algae, microbial mats, or accumulation of leaf litter and detritus also made significant contributions to vertical accretion. Turf algal mats in fringe and scrub forests accreted faster (2.7 mm yr -1) than leaf litter mats in basin forests (1.9 mm yr -1), but similarly to microbial mats in dwarf forests (2.1 mm yr -1). Surface accretion of mineral material accounted for only 0.2-3.3% of total vertical change. Those sites with high root contributions and/or rapid growth of living mats exhibited an elevation surplus (+2 to +8 mm yr -1), whereas those with low root inputs and low (or non-living) mat accumulation showed an elevation deficit (-1 to -5.7 mm yr -1). This study indicates that biotic processes of root production and benthic mat formation are important controls on accretion and elevation change in mangrove ecosystems common to the Caribbean Region. Quantification of specific biological controls on elevation provides better insight into how sustainability of such systems might be influenced by global (e.g., climate, atmospheric CO 2) and local (e.g., nutrients, disturbance) factors affecting organic matter accumulation, in addition to relative sea-level rise.

The comparison of microbial leakage in roots filled with resilon and gutta-percha: An in vitro study.

PubMed

Shashidhar, C; Shivanna, Vasundhara; Shivamurthy, Gb; Shashidhar, Jyothi

2011-01-01

The objective of this study was to compare bacterial leakage using streptococcus mutans through gutta-percha and a thermoplastic synthetic polymer based root canal filling material (Resilon) using two filling techniques. A total of 90 single-rooted extracted human teeth were subjected for the study. Teeth were divided into 6 groups of 10 and 3 control groups of 10 teeth each. All the samples were decoronated and the coronal surfaces of the roots were prepared perpendicular to the long axis of the root with a high-speed handpiece and a multipurpose bur using air water spray. The length of all the roots was prepared approximately 16 mm from the coronal surface to the apex of the root. Roots were filled using lateral and vertical condensation techniques with gutta-percha and AH26 sealer (Group 1 and 2) or with gutta-percha and epiphany sealer (Group 3 and 4). Group 5 and 6 were filled with Resilon and epiphany sealer using the lateral and vertical condensation techniques. A split chamber microbial leakage model was used in which S. mutans placed in the upper chamber could reach the lower chamber only through the filled root canal. Group 7 and 8 (positive control) were filled with Resilon and gutta-percha without sealer and tested with bacteria, whereas Group 7 (negative control) was sealed with wax to test the seal between the chambers. Data were analyzed using Kruskal-Wallis test and Mann-Whitney U test. All positive groups (Group 7 and 8) showed leakage within 1 hour of the start of the study (100%), whereas none of the negative control (Group 9) leaked. The roots obturated with Resilon and epiphany (Group 5 and 6) showed minimal leakage, i.e., each with 6 leakages, which was significantly less than gutta-percha (Group 1-4), in which approximately 80% of specimens with either sealer or techniques leaked. Kruskal-Wallis test showed statistical significance when all groups were compared (P<0.05). Mann-Whitney U test compared the respective groups and found Resilon groups superior to gutta-percha groups (P<0.05). This study demonstrated that the new polymer-based Resilon and epiphany sealer using two obturating techniques, i.e., lateral as well as vertical condensation found to be significantly better than the gutta-percha.

Influence of Procerum Root Disease on the Water Relations of Eastern White Pine (Pinus strobus L.)

Treesearch

J.R. Butnor; J.R. Seiler; J.A. Gray

2000-01-01

Procerum root disease (PRD) is caused by the deuteromycete fungus Leptogruphium procerum (Kendr.) Wingf, formerly Verticic ladiella procera (Kendr.) and is most commonly isolated from Pinus sp. L., though the fungus has been isolated from other conifer species including Fraser fir (Abies fraseri...

Vertical and horizontal root distribution of mature aspen clones: mechanisms for resource acquisition

NASA Astrophysics Data System (ADS)

Landhäusser, S. M.; Snedden, J.; Silins, U.; Devito, K. J.

2012-04-01

Spatial root distribution, root morphology, and intra- and inter-clonal connections of mature boreal trembling aspen clones (Populus tremuloides Michx.) were explored to shed light on the functional relationships between vertical and horizontal distribution of roots and the variation in soil water availability along hill slopes. Root systems of mature aspen were hydraulically excavated in large plots (6 m wide and 12 m long) and to a depth of 30 cm. Most aspen roots were located in the upper 20 cm of the soil and fine and coarse root occupancy was highest in the lower slope positions and lowest towards the upper hill slope position likely because of soil moisture availability. Observation of the root system distribution along the hill slope correlated well with the observation of greater leaf area carried by trees growing at the lower portion of the hill slope. Interestingly, trees growing at the bottom of the slope required also less sapwood area to support the same amount of leaf area of trees growing at the top of a slope. These observations appear to be closely related to soil moisture availability and with that greater productivity at the bottom of the slope. However, trees growing on the upper slope tended to have long lateral roots extending downslope, which suggests long distance water transport through these lateral feeder roots. Genetic analysis indicated that both intra- and inter-clonal root connections occur in aspen, which can play a role in the sharing of resources along moisture gradients. Root systems of boreal aspen growing on upper slope positions exhibited a combination of three attributes (1) asymmetric lateral root systems, that are skewed downslope, (2) deeper taproots, and (3) intra and inter-clonal root connections, which can all be considered adaptive strategies to avoid drought stress in upper slope positions.

Random River Fluctuations Shape the Root Profile of Riparian Plants

NASA Astrophysics Data System (ADS)

Perona, P.; Tron, S.; Gorla, L.; Schwarz, M.; Laio, F.; Ridolfi, L.

2015-12-01

Plant roots are recognized to play a key role in the riparian ecosystems: they contribute to the plant as well as to the streambank and bedforms stability, help to enhance the water quality of the river, and sustain the belowground biodiversity. The complexity of the root-system architecture recalls their remarkable ability to respond to environmental conditions, notably including soil heterogeneity, resource availability, and climate. In fluvial environments where nutrient availability is not a limiting factor for plant to grow, the root growth of phreatophytic plants is strongly influenced by water and oxygen availability in the soil. In this work, we demonstrate that the randomness of water table fluctuations, determined by streamflow stochastic variability, is likely to be the main driver for the root development strategy of riparian plants. A collection of root measurements from field and outdoor controlled experiments is used to demonstrate that the vertical root density distribution can be described by a simple analytical expression, whose parameters are linked to properties of soil, plant and water table fluctuations. This physically-based expression is able to predict riparian plant roots adaptability to different hydrological and pedologic scenarios in riverine environments. Hence, this model has great potential towards the comprehension of the effects of future climate and environmental changing conditions on plant adaptation and river ecomorphodynamic processes. Finally, we present an open access graphical user interface that we developed in order to estimate the vertical root distribution in fluvial environments and to make the model easily available to a wider scientific and professional audience.

UV-B Induced Generation of Reactive Oxygen Species Promotes Formation of BFA-Induced Compartments in Cells of Arabidopsis Root Apices

PubMed Central

Yokawa, Ken; Kagenishi, Tomoko; Baluška, František

2016-01-01

UV-B radiation is an important part of the electromagnetic spectrum emitted by the sun. For much of the period of biological evolution organisms have been exposed to UV radiation, and have developed diverse mechanisms to cope with this potential stress factor. Roots are usually shielded from exposure to UV by the surrounding soil, but may nevertheless be exposed to high energy radiation on the soil surface. Due to their high sensitivity to UV-B radiation, plant roots need to respond rapidly in order to minimize exposure on the surface. In addition to root gravitropism, effective light perception by roots has recently been discovered to be essential for triggering negative root phototropism in Arabidopsis. However, it is not fully understood how UV-B affects root growth and phototropism. Here, we report that UV-B induces rapid generation of reactive oxygen species which in turn promotes the formation of BFA-induced compartments in the Arabidopsis root apex. During unilateral UV-B irradiation of roots changes in auxin concentration on the illuminated side have been recorded. In conclusion, UV-B-induced and ROS-mediated stimulation of vesicle recycling promotes root growth and induces negative phototropism. PMID:26793199

Rooting Depths of Red Maple (Acer Rubrum L.) on Various Sites in the Lake States

Treesearch

Carl L. Haag; James E. Johnson; Gayne G. Erdmann

1989-01-01

Rooting depth and habit of red maple were observed on 60 sites in northern Wisconsin and Michigan as part of a regional soil-site studay. Vertical woody root extension on dry, outwash sites averaged 174 cm, which was significantly greater than the extension on sites with fragipans (139 cm) and on wet sites (112 cm). Site index was higher on wet sites and non-woody...

[Distribution of fine root biomass of main planting tree species in Loess Plateau, China].

PubMed

Jian, Sheng-Qi; Zhao, Chuan-Yan; Fang, Shu-Min; Yu, Kai

2014-07-01

The distribution of fine roots of Pinus tabuliformis, Populus tomentosa, Prunus armeniaca, Robinia pseudoacacia, Hippophae rhamnoides, and Caragana korshinskii was investigated by using soil core method and the fine root was defined as root with diameter less than 2 mm. The soil moisture and soil properties were measured. The results showed that in the horizontal direction, the distribution of fine root biomass of P. tabuliformis presented a conic curve, and the fine root biomass of the other species expressed logarithm correlation. Radial roots developed, the fine root biomass were concentrated within the scope of the 2-3 times crown, indicating that trees extended their roots laterally to seek water farther from the tree. In the vertical direction, the fine root biomass decreased with the increasing soil depth. Fine root biomass had significant negative correlation with soil water content and bulk density, while significant positive correlation with organic matter and total N contents.

Inhibition of polar calcium movement and gravitropism in roots treated with auxin-transport inhibitors

NASA Technical Reports Server (NTRS)

Lee, J. S.; Mulkey, T. J.; Evans, M. L.

1984-01-01

Primary roots of maize (Zea mays L.) and pea (Pisum sativum L.) exhibit strong positive gravitropism. In both species, gravistimulation induces polar movement of calcium across the root tip from the upper side to the lower side. Roots of onion (Allium cepa L.) are not responsive to gravity and gravistimulation induces little or no polar movement of calcium across the root tip. Treatment of maize or pea roots with inhibitors of auxin transport (morphactin, naphthylphthalamic acid, 2,3,5-triiodobenzoic acid) prevents both gravitropism and gravity-induced polar movement of calcium across the root tip. The results indicate that calcium movement and auxin movement are closely linked in roots and that gravity-induced redistribution of calcium across the root cap may play an important role in the development of gravitropic curvature.

Analysis of forces developed during root canal preparation with the balanced force technique.

PubMed

Blum, J Y; Machtou, P; Esber, S; Micallef, J P

1997-11-01

The aim of this study was to examine the forces and torque developed during root canal preparation with the balanced force technique using a recently described force-analyser device. A tooth was placed in a holder within the Endograph and forces and torques exerted were recorded. These parameters, which can be studied during preparation (on-line) or stored and examinated subsequently (off-line) generated endograms, which showed the forces generated with time. In addition, the endograms of preparations performed by students and endodontists, as well as deliberately induced failures in preparation technique (broken instruments), were compared. The values for the forces and torques depended on the size of the instruments and were related to the phase of the preparation. For the endodontists, the vertical and horizontal forces varied, respectively, from 0.08 +/- 0.01 kg for a size 15 to 0.65 +/- 0.10 kg for a size 45, and from 0.01 +/- 0.005 kg for a size 15 to 0.4 +/- 0.1 kg for a size 40. The torque varied from 0.08 +/- 1 kg mm-1 for a size 15 to 1.6 +/- 0.4 kg mm-1 for a size 45. With the endograms used as a reference, the relation between the developed vertical forces and the torque became more similar between the groups of endodontists and students. The Endograph provides a new approach to the analysis of preparation technique because it depicts the relationships between the different parameters of the preparation.

Control Law Synthesis for Vertical Fin Buffeting Alleviation Using Strain Actuation

NASA Technical Reports Server (NTRS)

Nitzsche, F.; Zimcik, D. G.; Ryall, T. G.; Moses, R. W.; Henderson, D. A.

1999-01-01

In the present investigation, the results obtained during the ground test of a closed-loop control system conducted on a full-scale fighter to attenuate vertical fin buffeting response using strain actuation are presented. Two groups of actuators consisting of piezoelectric elements distributed over the structure were designed to achieve authority over the first and second modes of the vertical fin. The control laws were synthesized using the Linear Quadratic Gaussian (LQG) method for a time-invariant control system. Three different pairs of sensors including strain gauges and accelerometers at different locations were used to close the feedback loop. The results demonstrated that measurable reductions in the root-mean-square (RMS) values of the fin dynamic response identified by the strain transducer at the critical point for fatigue at the root were achieved under the most severe buffet condition. For less severe buffet conditions, reductions of up to 58% were achieved.

Reversible loss of gravitropic sensitivity in maize roots after tip application of calcium chelators

NASA Technical Reports Server (NTRS)

Lee, J. S.; Mulkey, T. J.; Evans, M. L.

1983-01-01

The application of calcium chelating agents (EDTA or EGTA) to the tips of maize roots caused a loss of gravitropic sensitivity. When the chelator was replaced with calcium chloride, gravitropic sensitivity was restored. Asymmetric application of calcium chloride near the tip of a vertical root caused curvature toward the calcium source. When the calcium was applied to the upper surface of the tip of a root oriented horizontally, the root curved upward even though control roots exhibited strong downward curvature. Application of calcium chloride to the tips of decapped roots, which are known to be gravitropically insensitive, did not restore gravitropic sensitivity. However, asymmetric application of calcium chloride near the tips of decapped roots caused curvature toward the calcium source. Calcium may play a key role in linking gravity detection to gravitropic curvature in roots.

VERTICAL STRATIFICATION OF SOIL WATER STORAGE AND RELEASE DYNAMICS IN PACIFIC NORTHWEST CONIFEROUS FORESTS

EPA Science Inventory

abstract for journal article We characterized vertical variation in the seasonal depletion of stored soil moisture in old-growth ponderosa pine (OG-PP, xeric), and young and old-growth Douglas-fir (Y-DF, OG-DF, mesic) forests to evaluate changes in water availability for root up...

Comparative evaluation of rotary ProTaper, Profile, and conventional stepback technique on reduction in Enterococcus faecalis colony-forming units and vertical root fracture resistance of root canals.

PubMed

Singla, Mamta; Aggarwal, Vivek; Logani, Ajay; Shah, Naseem

2010-03-01

The purpose of this in vitro study was to evaluate the effect of various root canal instrumentation techniques with different instrument tapers on cleaning efficacy and resultant vertical root fracture (VRF) strength of the roots. Fifty human mandibular first premolar roots were enlarged to ISO size 20, inoculated with Enterococcus faecalis [ATCC2912] for 72 hours and divided into 5 groups: group I: prepared with .02 taper hand instruments ISO size 40; group II: Profile .04 taper size 40; group III: Profile .06 taper size 40; group IV: ProTaper size F4; and group V (control group) further divided into: Va: with bacterial inoculation and no mechanical instrumentation; and Group Vb: neither bacterial inoculation nor mechanical instrumentation. Cleaning efficacy was evaluated in terms of reduction of colony forming units (CFUs). The VRF strength was evaluated using D11 spreader as wedge in an Instron testing machine. Root canals instrumented with ProTaper and 6% Profile instruments showed maximum reduction in CFUs, with statistically insignificant difference between them. The VRF resistance decreased in all instrumented groups. The difference of VRF between 2% and 4% taper Profile groups was statistically insignificant (P = .195). One-way analysis of variance showed that canals instrumented with ProTaper F4 showed maximum reduction in VRF resistance compared with control uninstrumented group. Profile 6% taper instruments offer the advantage of maximum debridement without significant reduction in root fracture resistance. Copyright 2010 Mosby, Inc. All rights reserved.

Root foraging elicits niche complementarity-dependent yield advantage in the ancient ‘three sisters’ (maize/bean/squash) polyculture

PubMed Central

Zhang, Chaochun; Postma, Johannes A.; York, Larry M.; Lynch, Jonathan P.

2014-01-01

Background and Aims Since ancient times in the Americas, maize, bean and squash have been grown together in a polyculture known as the ‘three sisters’. This polyculture and its maize/bean variant have greater yield than component monocultures on a land-equivalent basis. This study shows that below-ground niche complementarity may contribute to this yield advantage. Methods Monocultures and polycultures of maize, bean and squash were grown in two seasons in field plots differing in nitrogen (N) and phosphorus (P) availability. Root growth patterns of individual crops and entire polycultures were determined using a modified DNA-based technique to discriminate roots of different species. Key Results The maize/bean/squash and maize/bean polycultures had greater yield and biomass production on a land-equivalent basis than the monocultures. Increased biomass production was largely caused by a complementarity effect rather than a selection effect. The differences in root crown architecture and vertical root distribution among the components of the ‘three sisters’ suggest that these species have different, possibly complementary, nutrient foraging strategies. Maize foraged relatively shallower, common bean explored the vertical soil profile more equally, while the root placement of squash depended on P availability. The density of lateral root branching was significantly greater for all species in the polycultures than in the monocultures. Conclusions It is concluded that species differences in root foraging strategies increase total soil exploration, with consequent positive effects on the growth and yield of these ancient polycultures. PMID:25274551

Degradation of trans-polyisoprene after root filling with thermoplasticized techniques.

PubMed

Maniglia-Ferreira, C; Bönecker, G; Silva, J B A; de Paula, R C M; Feitosa, J P A; Souza-Filho, F J

2008-04-01

To evaluate ex vivo degradation of gutta-percha following six thermoplastic obturation techniques. Ninety human-extracted mandibular premolars were selected and divided randomly into nine groups for filling. Group 1: thermomechanical compaction for 3 s with Konne gutta-percha points (Konne Ind. e Com. de Mat. Odontol., Belo Horizonte, MG, Brazil); Group 2: thermomechanical compaction for 3 s with Dentsply TP gutta-percha points (Dentsply Indústria e Comércio Ltda, Petrópolis, R.J. Brazil); Group 3: thermomechanical compaction for 10 s with Konne; Group 4: thermomechanical compaction for 10 s with Dentsply TP; Group 5: warm vertical condensation using System B (EIE/Analytic, Richmond, WA, USA) with Konne; Group 6: warm vertical condensation using System B with Dentsply TP; Group 7: vertical condensation with Konne; Group 8: vertical condensation with Dentsply TP; Group 9: Microseal cone (Analytic Endodontics, Glendora, CA, USA). A further four groups were assessed without using teeth, Group 10: Microseal microflow (Analytic Endodontics); Group 11: Obtura (Obtura Corporation, Penton, MO, USA); Group 12: Obtura flow (Obtura Corporation); Group 13: Thermafil (Dentsply Maillefer, Tulsa, OK, USA). The filling material was removed from the root canal and trans-1,4-polyisoprene isolated by solubilization of the root filling remnants in chloroform followed by filtration and centrifugation. By gel permeation chromatography and infrared spectroscopy, the occurrence and degree of degradation were assessed. The results were analysed statistically using the Kruskal-Wallis test. With differential scanning calorimetry, the thermal behaviour of the gutta-percha was determined. A significant decrease in polymer molar mass and the production of carboxyl and hydroxyl groups in the polymer were observed with thermomechanical compaction used for 10 s and vertical condensation filling techniques (P = 0.0001 and P = 0.0005, respectively). Other techniques caused no polymer degradation. Polyisoprene degrades with high temperature. Thermomechanical compaction for 10 s and vertical condensation were associated with the greatest degradative process.

Vertical Root Fracture initiation in curved roots after root canal preparation: A dentinal micro-crack analysis with LED transillumination

PubMed Central

Martín-Biedma, Benjamín; Varela-Patiño, Purificación; Ruíz-Piñón, Manuel; Castelo-Baz, Pablo

2017-01-01

Background One of the causative factors of root defects is the increased friction produced by rotary instrumentation. A high canal curvature may increase stress, making the tooth more susceptible to dentinal cracks. The purpose of this study was to evaluate dentinal micro-crack formation with the ProTaper NEXT and ProTaper Universal systems using LED transillumination, and to analyze the micro-crack generated at the point of maximum canal curvature. Material and Methods 60 human mandibular premolars with curvatures between 30–49° and radii between 2–4 mm were used. The root canals were instrumented using the Protaper Universal® and Protaper NEXT® systems, with the aid of the Proglider® system. The obtained samples were sectioned transversely before subsequent analysis with LED transillumination at 2 mm and 8 mm from the apex and at the point of maximum canal curvature. Defects were scored: 0 for no defects; and 1 for micro-cracks. Results Root defects were not observed in the control group. The ProTaper NEXT system caused fewer defects (16.7%) than the ProTaper Universal system (40%) (P<0.05). The ProTaper Universal system caused significantly more micro-cracks at the point of maximum canal curvature than the ProTaper NEXT system (P<0.05). Conclusions Rotary instrumentation systems often generate root defects, but the ProTaper NEXT system generated fewer dentinal defects than the ProTaper Universal system. A higher prevalence of defects was found at the point of maximum curvature in the ProTaper Universal group. Key words:Curved root, Micro-crack, point of maximum canal curvature, ProTaper NEXT, ProTaper Universal, Vertical root fracture. PMID:29167712

A new genetic factor for root gravitropism in rice (Oryza sativa L.).

PubMed

Shi, Jiang-hua; Hao, Xi; Wu, Zhong-chang; Wu, Ping

2009-10-01

Root gravitropism is one of the important factors to determine root architecture. To understand the mechanism underlying root gravitropism, we isolated a rice (Xiushui63) mutant defective in root gravitropism, designated as gls1. Vertical sections of root caps revealed that gls1 mutant displayed normal distribution of amyloplast in the columella cells compared with the wild type. The gls1 mutant was less sensitive to 2,4-dichlorophenoxyacetic acid (2,4-D) and alpha-naphthaleneacetic acid (NAA) than the wild type. Genetic analysis indicated that the phenotype of gls1 mutant was caused by a single recessive mutation, which is mapped in a 255-kb region between RM16253 and CAPS1 on the short arm of chromosome 4.

Saltmarsh creek bank stability: Biostabilisation and consolidation with depth

NASA Astrophysics Data System (ADS)

Chen, Y.; Thompson, C. E. L.; Collins, M. B.

2012-03-01

The stability of cohesive sediments of a saltmarsh in Southern England was measured in the field and the laboratory using a Cohesive Strength Meter (CSM) and a shear vane apparatus. Cores and sediment samples were collected from two tidal creek banks, covered by Atriplex portulacoides (Sea Purslane) and Juncus maritimus (Sea Rush), respectively. The objectives of the study were to examine the variation of sediment stability throughout banks with cantilevers present and investigate the influence of roots and downcore consolidation on bank stability. Data on erosion threshold and shear strength were interpreted with reference to bank depth, sediment properties and biological influences. The higher average erosion threshold was from the Sea Purslane bank whilst the Sea Rush bank showed higher average vane shear strength. The vertical variation in core sediment stability was mainly affected by roots and downcore consolidation with depth. The data obtained from the bank faces revealed that vertical variations in both erosion threshold and vane shear strength were affected primarily by roots and algae. A quantitative estimate of the relative contributions of roots and downcore consolidation to bank sediment stability was undertaken using the bank stability data and sediment density data. This showed that roots contributed more to the Sea Purslane bank stability than downcore consolidation, whilst downcore consolidation has more pronounced effects on the Sea Rush bank stability.

Noise amplification of plant gravisensing

NASA Astrophysics Data System (ADS)

Ma, Zhong; Hasenstein, Karl H.

A common problem in sensory physiology is the detection of weak signals, such as that produced by the repositioning of statoliths (amyloplasts) in gravisensing cells, from a noisy background. As in other studied biological mechanosensory systems, it is conceivable that the gravisensing process may be amplified by stochastic resonance and nonlinear noise-assisted effects. We therefore investigated the possible dependency of gravisensing on vibrational or thermodynamic noise by examining the effect of external oscillation and temperature on the rate of gravitropic curvature in flax (Linum usitatissimum L.) roots. Roots were oscillated for 15 min prior to or during gravistimulation, either parallel or perpendicular to the root axis. The effect of oscillation was dependent on its direction as well as frequency and amplitude. Initial curvature was most effectively enhanced by vertical oscillations of 5 Hz and 0.5 mm amplitude prior to reorientation. Vertically oscillated roots reached half-maximal curvature 32 min after reorientation, about 18 min earlier than non-oscillated roots. The enhancing effect of vibration on curvature subsided with a half-time of about 20 min. The temperature dependency of the graviresponse indicated that thermodynamic noise also impacted gravity perception. For vibrations and temperature studies, the presentation times decreased almost 6-fold. Our data indicate that gravisensing may depend on or be enhanced by thermodynamic or mechanical noise.

Vertical stratification of soil water storage and release dynamics in Pacific Northwest coniferous forests.

Treesearch

J.M. Warren; F.C. Meinzer; J.R. Brooks; J.C. Domec

2005-01-01

We characterized vertical variation in the seasonal release of stored soil moisture in old-growth ponderosa pine (OG-PP, xeric), and young and old-growth Douglas-fir (Y-DF, OG-DF, mesic) forests to evaluate changes in water availability for root uptake. Soil water potential (ψ) and volumetric water content (θ...

A simple three-dimensional stent for proper placement of mini-implant

PubMed Central

2013-01-01

Background This paper deals with the fabrication of a three-dimensional stent which is simple in design but provides an accurate placement of a mini-implant in three planes of space, namely, sagittal (root proximity), vertical (attached gingiva/alveolar mucosa) and transverse (angulation). Findings The stent is made of 0.018 × 0.025 in. stainless steel archwire which consists of a ‘u loop’ angulated at 20°, a vertical limb, a horizontal limb and a stop. The angulation of the ‘u’ helps in the placement of the mini-implant at 70° to the long axis of the tooth. The vertical height is determined such that the mini-implant is placed at the mucogingival junction. The mini-implant is placed with the aid of the stent, and its angulation and proximity to the adjacent roots are checked with a cone beam computed tomography image. The cone beam computed tomography image showed the mini-implant at an angle of 70° to the long axis of the tooth. There is no contact between mini-implant and the roots of the adjacent teeth. Conclusion This stent is simple, easy to fabricate, cost-effective, and provides ease of insertion/removal, and three-dimensional orientation of the mini-implant. PMID:24326158

Root cytoskeleton: its role in perception of and response to gravity

NASA Technical Reports Server (NTRS)

Baluska, F.; Hasenstein, K. H.

1997-01-01

We have critically evaluated the possible functions of the plant cytoskeleton in root gravisensing and graviresponse and discussed the evidence that microtubules (MTs) and actin microfilaments (MFs) do not control differential cell growth during bending of roots. On the other hand, MF and MT networks are envisaged to participate in gravisensing because of the mechanical properties of the cytoskeletal structures that interconnect plant cell organelles with the plasma membrane. In restrained gravisensing, forces are suggested to be transmitted to membranes because large-scale gravity-dependent repositioning of organelles is effectively prevented due to the cytoskeleton-mediated anchorage of their envelopes at the plasma membrane. From the cytoskeletal point of view, we can also envisage an unrestrained gravity sensing when cytoskeletal tethers are not strong enough to preserve the tight control over distribution of organelles and the latter, if heavy enough, are allowed to sediment towards the physical bottom of cells. This situation obviously occurs in root cap statocytes because these uniquely organized cells are depleted of prominent actin MF bundles, endoplasmic MT arrays, and ER elements in their internal cytoplasm. Nevertheless, indirect evidence clearly indicates that sedimented root cap statoliths are enmeshed within fine but dynamic MF networks and that their behaviour is obviously under, at least partial, cytoskeletal control. The actomyosin-enriched domain among and around amyloplasts is proposed to increase the perception of gravity due to the grouping effect of sedimenting statoliths. Cytoskeletal links between myosin-rich statoliths, and cell peripheries well equipped with dense cortical MTs, membrane-associated cytoskeleton, as well as with ER elements, would allow efficient restrained gravisensing only at the statocyte cell cortex. As a consequence of cytoskeletal depletion in the internal statocyte cytoplasm and bulk sedimentation of large amyloplasts, restrained gravisensing is spatially restricted to the bottom of the statocyte irrespective of whether roots are vertical or horizontal. This spatial aspect allows for efficient gravisensing via amplification of gravity-induced impacts on the cellular architecture, a phenomenon which is unique to root cap statocytes.

Influence of Intracanal Materials in Vertical Root Fracture Pathway Detection with Cone-beam Computed Tomography.

PubMed

Dutra, Kamile Leonardi; Pachêco-Pereira, Camila; Bortoluzzi, Eduardo Antunes; Flores-Mir, Carlos; Lagravère, Manuel O; Corrêa, Márcio

2017-07-01

Investigating the vertical root fracture (VRF) pathway under different clinical scenarios may help to diagnose this condition properly. We aimed to determine the capability and intrareliability of VRF pathway detection through cone-beam computed tomographic (CBCT) imaging as well as analyze the influence of different intracanal and crown materials. VRFs were mechanically induced in 30 teeth, and 4 clinical situations were reproduced in vitro: no filling, gutta-percha, post, and metal crown. A Prexion (San Mateo, CA) 3-dimensional tomographic device was used to generate 104 CBCT scans. The VRF pathway was determined by using landmarks in the Avizo software (Version 8.1; FEI Visualization Sciences Group, Burlington, MA) by 1 observer repeated 3 times. Analysis of variance and post hoc tests were applied to compare groups. Intrareliability demonstrated an excellent agreement (intraclass correlation coefficient mean = 0.93). Descriptive analysis showed that the fracture line measurement was smaller in the post and metal crown groups than in the no-filling and gutta-percha groups. The 1-way analysis of variance test found statistically significant differences among the groups measurements. The Bonferroni correction showed statistically significant differences related to the no-filling and gutta-percha groups versus the post and metal crown groups. The VRF pathway can be accurately detected in a nonfilled tooth using limited field of view CBCT imaging. The presence of gutta-percha generated a low beam hardening artifact that did not hinder the VRF extent. The presence of an intracanal gold post made the fracture line appear smaller than it really was in the sagittal images; in the axial images, a VRF was only detected when the apical third was involved. The presence of a metal crown did not generate additional artifacts on the root surface compared to the intracanal gold post by itself. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Sealer penetration into dentinal tubules in the presence or absence of smear layer: a confocal laser scanning microscopic study.

PubMed

Kuçi, Astrit; Alaçam, Tayfun; Yavaş, Ozer; Ergul-Ulger, Zeynep; Kayaoglu, Guven

2014-10-01

The aim of this study was to test the dentinal tubule penetration of AH26 (Dentsply DeTrey, Konstanz, Germany) and MTA Fillapex (Angelus, Londrina, PR, Brazil) in instrumented root canals obturated by using cold lateral compaction or warm vertical compaction techniques in either the presence or absence of the smear layer. Forty-five extracted single-rooted human mandibular premolar teeth were used. The crowns were removed, and the root canals were instrumented by using the Self-Adjusting File (ReDent-Nova, Ra'anana, Israel) with continuous sodium hypochlorite (2.6%) irrigation. Final irrigation was either with 5% EDTA or with sodium hypochlorite. The canals were dried and obturated by using rhodamine B-labeled AH26 or MTA Fillapex in combination with the cold lateral compaction or the warm vertical compaction technique. After setting, the roots were sectioned horizontally at 4-, 8-, and 12-mm distances from the apical tip. On each section, sealer penetration in the dentinal tubules was measured by using confocal laser scanning microscopy. Regardless of the usage of EDTA, MTA Fillapex, compared with AH26, was associated with greater sealer penetration when used with the cold lateral compaction technique, and, conversely, AH26, compared with MTA Fillapex, was associated with greater sealer penetration when used with the warm vertical compaction technique (P < .05). Removal of the smear layer increased the penetration depth of MTA Fillapex used with the cold lateral compaction technique (P < .05); however, it had no significant effect on the penetration depth of AH26. Greater sealer penetration could be achieved with either the MTA Fillapex-cold lateral compaction combination or with the AH26-warm vertical compaction combination. Smear layer removal was critical for the penetration of MTA Fillapex; however, the same did not hold for AH26. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Lipopolysaccharides of Rhizobium etli strain G12 act in potato roots as an inducing agent of systemic resistance to infection by the cyst nematode Globodera pallida.

PubMed

Reitz, M; Rudolph, K; Schröder, I; Hoffmann-Hergarten, S; Hallmann, J; Sikora, R A

2000-08-01

Recent studies have shown that living and heat-killed cells of the rhizobacterium Rhizobium etli strain G12 induce in potato roots systemic resistance to infection by the potato cyst nematode Globodera pallida. To better understand the mechanisms of induced resistance, we focused on identifying the inducing agent. Since heat-stable bacterial surface carbohydrates such as exopolysaccharides (EPS) and lipopolysaccharides (LPS) are essential for recognition in the symbiotic interaction between Rhizobium and legumes, their role in the R. etli-potato interaction was studied. EPS and LPS were extracted from bacterial cultures, applied to potato roots, and tested for activity as an inducer of plant resistance to the plant-parasitic nematode. Whereas EPS did not affect G. pallida infection, LPS reduced nematode infection significantly in concentrations as low as 1 and 0.1 mg ml(-1). Split-root experiments, guaranteeing a spatial separation of inducing agent and challenging pathogen, showed that soil treatments of one half of the root system with LPS resulted in a highly significant (up to 37%) systemic induced reduction of G. pallida infection of potato roots in the other half. The results clearly showed that LPS of R. etli G12 act as the inducing agent of systemic resistance in potato roots.

Glucose control of root growth direction in Arabidopsis thaliana.

PubMed

Singh, Manjul; Gupta, Aditi; Laxmi, Ashverya

2014-07-01

Directional growth of roots is a complex process that is modulated by various environmental signals. This work shows that presence of glucose (Glc) in the medium also extensively modulated seedling root growth direction. Glc modulation of root growth direction was dramatically enhanced by simultaneous brassinosteroid (BR) application. Glc enhanced BR receptor BRASSINOSTEROID INSENSITIVE1 (BRI1) endocytosis from plasma membrane to early endosomes. Glc-induced root deviation was highly enhanced in a PP2A-defective mutant, roots curl in naphthyl phthalamic acid 1-1 (rcn1-1) suggesting that there is a role of phosphatase in Glc-induced root-growth deviation. RCN1, therefore, acted as a link between Glc and the BR-signalling pathway. Polar auxin transport worked further downstream to BR in controlling Glc-induced root deviation response. Glc also affected other root directional responses such as root waving and coiling leading to altered root architecture. High light intensity mimicked the Glc-induced changes in root architecture that were highly reduced in Glc-signalling mutants. Thus, under natural environmental conditions, changing light flux in the environment may lead to enhanced Glc production/response and is a way to manipulate root architecture for optimized development via integrating several extrinsic and intrinsic signalling cues. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Habitability from Tidally Induced Tectonics

NASA Astrophysics Data System (ADS)

Valencia, Diana; Tan, Vivian Yun Yan; Zajac, Zachary

2018-04-01

The stability of Earth’s climate on geological timescales is enabled by the carbon–silicate cycle that acts as a negative feedback mechanism stabilizing surface temperatures via the intake and outgassing of atmospheric carbon. On Earth, this thermostat is enabled by plate tectonics that sequesters outgassed CO2 back into the mantle via weathering and subduction at convergent margins. Here we propose a separate tectonic mechanism—vertical recycling—that can serve as the vehicle for CO2 outgassing and sequestration over long timescales. The mechanism requires continuous tidal heating, which makes it particularly relevant to planets in the habitable zone of M stars. Dynamical models of this vertical recycling scenario and stability analysis show that temperate climates stable over timescales of billions of years are realized for a variety of initial conditions, even as the M star dims over time. The magnitude of equilibrium surface temperatures depends on the interplay of sea weathering and outgassing, which in turn depends on planetary carbon content, so that planets with lower carbon budgets are favored for temperate conditions. The habitability of planets such as found in the Trappist-1 system may be rooted in tidally driven tectonics.

Aerothermoelastic Analysis of a NASP-Like Vertical Fin

NASA Technical Reports Server (NTRS)

Rodgers, John P.

1992-01-01

Several aeroelastic stability analyses for a vertical fin similar to that of the National Aero-Space Plane are described. The objectives of the study were to design and obtain an experimental data base for a supersonic wind-tunnel model of the fin in order to examine the effects of thermal loading on the flutter characteristics. This paper describes the preliminary efforts to design the wind-tunnel model, including several of the geometric parameter variations that were analyzed. The dominant flutter mechanism involved a flap vibration mode and a fin bending mode. Variation of the thicknesses of flap and root flexures, used to attach the flap to the fin, and the fin to a support, significantly affected the flutter boundary. Uniform thermal loads, affecting only material properties, had little effect, as did the application of different uniform temperatures to each side of the fin. In contrast, the application of significant chord-wise thermal gradients induced stresses which reduced the flutter dynamic pressure by as much as 37 percent. For less extreme distributed loading, the low-aspect ratio fin was relatively unaffected.

Biomechanical studies on the effect of iatrogenic dentin removal on vertical root fractures.

PubMed

Ossareh, A; Rosentritt, M; Kishen, A

2018-01-01

The aim of this study was to understand the mechanism by which iatrogenic root dentin removal influences radicular stress distribution and subsequently affects the resistance to vertical root fractures (VRF) in endodontically treated teeth. The experiments were conducted in two phases. Phase 1: freshly extracted premolar teeth maintained in phosphate-buffered saline were instrumented to simulate three different degrees of dentin removal, designated as low, medium, and extreme groups. Micro-Ct analyzes were performed to quantitatively determine: (a) the amount of dentin removed, (b) the remaining dentin volume, and (c) the moment of inertia of root dentin. The specimens were then subjected to thermomechanical cycling and continuous loading to determine (a) the mechanical load to fracture and (b) dentin microcracking (fractography) using scanning electron microscopy. Phase 2: Finite element analysis was used to evaluate the influence of dentin removal on the stress distribution pattern in root dentin. The data obtained were analyzed using one-way ANOVA and Tukey's post hoc test ( P < 0.05). Phase 1: A significantly greater volume of dentin was removed from teeth in extreme group when compared to low group ( P < 0.01). The mechanical analysis showed that the load to fracture was significantly lower in teeth from extreme group ( P < 0.05). A linear relationship was observed between the moment of inertia and load to fracture in all experimental groups ( R 2 = 0.52). Fractography showed that most microcracks were initiated from the root canal walls in extreme group. Phase 2: The numerical analysis showed that the radicular stress distribution increased apically and buccolingually with greater degree of root canal dentin removal. The combined experimental/numerical analyses highlighted the influence of remaining root dentin volume on the radicular bending resistance, stress distribution pattern, and subsequent propensity to VRF.

[Root canal treatment of mandibular first premolar with 4 root canals: a case report].

PubMed

Liu, Xin-yang; Zhan, Fu-Liang

2015-10-01

The mandibular first premolar can be considered one of the most challenging teeth to treat, due to the complexity of its root canal morphology and increased incidence of multiple canals. A case of endodontic treatment of a mandibular first premolar exhibiting a total of 4 distinct root canals and 4 apical foramina was described. Anatomic variation of root canal morphology should be considered in endodontic treatment to ensure a favorable healing outcome, and its identification could be enhanced by careful examination using a dental operating microscope. Obturation of root canals using a warm vertical compaction technique with a highly-radiopaque root canal sealer, such as AH Plus, after careful ultrasonic activated irrigation might allow the flow of sealer into the narrowed but unprepared part of the canal, thereby facilitating optimum chemo-mechanical debridement of the root canal system.

Hydraulic Redistribution: A Modeling Perspective

NASA Astrophysics Data System (ADS)

Daly, E.; Verma, P.; Loheide, S. P., III

2014-12-01

Roots play a key role in the soil water balance. They extract and transport water for transpiration, which usually represents the most important soil water loss in vegetated areas, and can redistribute soil water, thereby increasing transpiration rates and enhancing root nutrient uptake. We present here a two-dimensional model capable of describing two key aspects of root water uptake: root water compensation and hydraulic redistribution. Root water compensation is the ability of root systems to respond to the reduction of water uptake from areas of the soil with low soil water potential by increasing the water uptake from the roots in soil parts with higher water potential. Hydraulic redistribution is a passive transfer of water through the root system from areas of the soil with greater water potential to areas with lower water potential. Both mechanisms are driven by gradients of water potential in the soil and the roots. The inclusion of root water compensation and hydraulic redistribution in models can be achieved by describing root water uptake as a function of the difference in water potential between soil and root xylem. We use a model comprising the Richards equation for the water flow in variably saturated soils and the Darcy's equation for the water flow in the xylem. The two equations are coupled via a sink term, which is assumed to be proportional to the difference between soil and xylem water potentials. The model is applied in two case studies to describe vertical and horizontal hydraulic redistribution and the interaction between vegetation with different root depths. In the case of horizontal redistribution, the model is used to reproduce the fluxes of water across the root system of a tree subjected to uneven irrigation. This example can be extended to situations when only part of the root system has access to water, such as vegetation near creeks, trees at the edge of forests, and street trees in urban areas. The second case is inspired by recent agro-ecosystems experiments that combined different vegetation species to increase crop yield. The presence of deep rooted plants (nursing species) near shallow rooted crops (nursed species) enhanced crop growth thanks to vertical and horizontal hydraulic redistribution. The model is able to reproduce the patterns of water redistribution observed in this scenario.

In vitro induction of lipo-chitooligosaccharide production in Bradyrhizobium japonicum cultures by root extracts from non-leguminous plants.

PubMed

Lian, Bin; Souleimanov, Alfred; Zhou, Xiaomin; Smith, Donald L

2002-01-01

Bradyrhizobium japonicum can form a N2-fixing symbiosis with compatible leguminous plants. It can also act as a plant-growth promoting rhizobacterium (PGPR) for non-legume plants, possibly through production of lipo-chitooligosaccharides (LCOs), which should have the ability to induce disease resistance responses in plants. The objective of this work was to determine whether non-leguminous crop plants can induce LCO formation by B. japonicum cultures. Cultures treated with root extracts of soybean, corn, cotton or winter wheat were assayed for presence and level of LCO. Root extracts of soybean, corn and winter wheat all induced LCO production, with extracts of corn inducing the greatest amounts. Root washings of corn also induced LCO production, but less than the root extract. These results indicated that the stimulation of non-legume plant growth by B. japonicum could be through the production of LCOs, induced by materials excreted by the roots of non-legume plants.

Influence of nickel-titanium rotary systems with varying tapers on the biomechanical behaviour of maxillary first premolars under occlusal forces: a finite element analysis study.

PubMed

Askerbeyli Örs, S; Serper, A

2018-05-01

To evaluate the effect of three nickel-titanium (Ni-Ti) rotary systems with varying tapers on stress distribution and to analyse potential fracture patterns as well as the volume of fracture-susceptible regions in two-rooted maxillary premolars. The root canals of three single-rooted premolars were prepared with either HeroShaper (Micro-Mega, Besançon, France) to (size 30, .04 taper), Revo-S (Micro-Mega) to AS30 (size 30, .06 taper) or ProTaper Universal (Dentsply Maillefer, Ballaigues, Switzerland) to F3 (size 30, .09 taper) Ni-Ti files. The three root canals were scanned using micro-computed tomography (μCT) (Skyscan 1174, Skyscan, Kontich, Belgium) and modelled according to the μCT data. An intact tooth model with a root length of 16 mm was also constructed based on μCT images of an extracted maxillary premolar with two roots. New models were constructed by replacing both of the original canals of the intact two-rooted premolar model with the modelled canals prepared with the HeroShaper, Revo-S or ProTaper Universal system. Occlusal forces of 200 N were applied in oblique and vertical directions. Finite element analysis was performed using Abaqus FEA software (Abaqus 6.14, ABAQUS Inc., Providence, RI, USA). Upon the application of oblique occlusal forces, the palatal external cervical root surface and the bifurcation (palatal side of the buccal root) in tooth models experienced the highest maximum principal (Pmax) stresses. The application of vertical forces resulted in minor Pmax stress values. Models prepared using the ProTaper system exhibited the highest Pmax stress values. The intact models exhibited the lowest Pmax stress values followed by the models prepared with the HeroShaper system. The differences in Pmax stress values amongst the different groups of models were mathematically minimal under normal occlusal forces. Rotary systems with varying tapers might predispose the root fracture on the palatal side of the buccal root and cervical palatal root surface in two-rooted premolars. © 2017 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Velocity and Drag Evolution From the Leading Edge of a Model Mangrove Forest

NASA Astrophysics Data System (ADS)

Maza, Maria; Adler, Katherine; Ramos, Diogo; Garcia, Adrian Mikhail; Nepf, Heidi

2017-11-01

An experimental study of unidirectional flow through a model mangrove forest measured both velocity and forces on individual trees. The individual trees were 1/12th scale models of mature Rhizophora, including 24 prop roots distributed in a three-dimensional layout. Thirty-two model trees were distributed in a staggered array producing a 2.5 m long forest. The velocity evolved from a boundary layer profile at the forest leading edge to a vertical profile determined by the vertical distribution of frontal area, with significantly higher velocity above the prop roots. Fully developed conditions were reached at the fifth tree row from the leading edge. Within the root zone the velocity was reduced by up to 50% and the TKE was increased by as much as fivefold, relative to the upstream conditions. TKE in the root zone was mainly produced by root and trunk wakes, and it agreed in magnitude with the estimation obtained using the Tanino and Nepf (2008) formulation. Maximum TKE occurred at the top of the roots, where a strong shear region was associated with the change in frontal area. The drag measured on individual trees decreased from the leading edge and reached a constant value at the fifth row and beyond, i.e., in the fully developed region. The drag exhibited a quadratic dependence on velocity, which justified the definition of a quadratic drag coefficient. Once the correct drag length-scale was defined, the measured drag coefficients collapsed to a single function of Reynolds number.

Loop Heat Pipe Temperature Oscillation Induced by Gravity Assist and Reservoir Heating

NASA Technical Reports Server (NTRS)

Ku, Jentung; Garrison, Matthew; Patel, Deepak; Robinson, Franklin; Ottenstein, Laura

2015-01-01

The Laser Thermal Control System (LCTS) for the Advanced Topographic Laser Altimeter System (ATLAS) to be installed on NASA's Ice, Cloud, and Land Elevation Satellite (ICESat-2) consists of a constant conductance heat pipe and a loop heat pipe (LHP) with an associated radiator. During the recent thermal vacuum testing of the LTCS where the LHP condenser/radiator was placed in a vertical position above the evaporator and reservoir, it was found that the LHP reservoir control heater power requirement was much higher than the analytical model had predicted. Even with the control heater turned on continuously at its full power, the reservoir could not be maintained at its desired set point temperature. An investigation of the LHP behaviors found that the root cause of the problem was fluid flow and reservoir temperature oscillations, which led to persistent alternate forward and reversed flow along the liquid line and an imbalance between the vapor mass flow rate in the vapor line and liquid mass flow rate in the liquid line. The flow and temperature oscillations were caused by an interaction between gravity and reservoir heating, and were exacerbated by the large thermal mass of the instrument simulator which modulated the net heat load to the evaporator, and the vertical radiator/condenser which induced a variable gravitational pressure head. Furthermore, causes and effects of the contributing factors to flow and temperature oscillations intermingled.

Plant domestication and the assembly of bacterial and fungal communities associated with strains of the common sunflower, Helianthus annuus.

PubMed

Leff, Jonathan W; Lynch, Ryan C; Kane, Nolan C; Fierer, Noah

2017-04-01

Root and rhizosphere microbial communities can affect plant health, but it remains undetermined how plant domestication may influence these bacterial and fungal communities. We grew 33 sunflower (Helianthus annuus) strains (n = 5) that varied in their extent of domestication and assessed rhizosphere and root endosphere bacterial and fungal communities. We also assessed fungal communities in the sunflower seeds to investigate the degree to which root and rhizosphere communities were influenced by vertical transmission of the microbiome through seeds. Neither root nor rhizosphere bacterial communities were affected by the extent of sunflower domestication, but domestication did affect the composition of rhizosphere fungal communities. In particular, more modern sunflower strains had lower relative abundances of putative fungal pathogens. Seed-associated fungal communities strongly differed across strains, but several lines of evidence suggest that there is minimal vertical transmission of fungi from seeds to the adult plants. Our results indicate that plant-associated fungal communities are more strongly influenced by host genetic factors and plant breeding than bacterial communities, a finding that could influence strategies for optimizing microbial communities to improve crop yields. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

Control of Adventitious Root Architecture in Rice by Darkness, Light, and Gravity1[OPEN

PubMed Central

2018-01-01

Rice (Oryza sativa) is a semiaquatic plant that is well adapted to partial flooding. Rice stems develop adventitious root (AR) primordia at each node that slowly mature but emerge only when the plant gets flooded, leading to the formation of a whole new secondary root system upon flooding. AR growth is induced by ethylene that accumulates in submerged plant tissues due to its lowered diffusion rate in water. Here, we report that the architecture of the secondary root system in flooded rice plants is controlled not only by altered gas diffusion but also by gravity and light. While ethylene promotes the emergence and growth of ARs, gravity and light determine their gravitropic setpoint angle (i.e. the deviation of growth direction relative to vertical). ARs grow upward at about 120° in the dark and downward at 54° in the light. The upward growth direction is conserved in indica and japonica rice varieties, suggestive of a conserved trait in rice. Experiments with a klinostat and with inverted stem orientation revealed that gravity promotes upward growth by about 10°. Red, far-red, and blue light lead to negative phototropism in a dose-dependent manner, with blue light being most effective, indicating that phytochrome and blue light signaling control AR system architecture. The cpt1 (coleoptile phototropism1) mutant, which lacks one of the phototropin-interacting CPT proteins, shows reduced sensitivity to blue light. Hence, the gravitropic setpoint angle of rice ARs is controlled by genetic and environmental factors that likely balance the need for oxygen supply (upward growth) with avoidance of root desiccation (downward growth). PMID:29242375

Control of Adventitious Root Architecture in Rice by Darkness, Light, and Gravity.

PubMed

Lin, Chen; Sauter, Margret

2018-02-01

Rice ( Oryza sativa ) is a semiaquatic plant that is well adapted to partial flooding. Rice stems develop adventitious root (AR) primordia at each node that slowly mature but emerge only when the plant gets flooded, leading to the formation of a whole new secondary root system upon flooding. AR growth is induced by ethylene that accumulates in submerged plant tissues due to its lowered diffusion rate in water. Here, we report that the architecture of the secondary root system in flooded rice plants is controlled not only by altered gas diffusion but also by gravity and light. While ethylene promotes the emergence and growth of ARs, gravity and light determine their gravitropic setpoint angle (i.e. the deviation of growth direction relative to vertical). ARs grow upward at about 120° in the dark and downward at 54° in the light. The upward growth direction is conserved in indica and japonica rice varieties, suggestive of a conserved trait in rice. Experiments with a klinostat and with inverted stem orientation revealed that gravity promotes upward growth by about 10°. Red, far-red, and blue light lead to negative phototropism in a dose-dependent manner, with blue light being most effective, indicating that phytochrome and blue light signaling control AR system architecture. The cpt1 ( coleoptile phototropism1 ) mutant, which lacks one of the phototropin-interacting CPT proteins, shows reduced sensitivity to blue light. Hence, the gravitropic setpoint angle of rice ARs is controlled by genetic and environmental factors that likely balance the need for oxygen supply (upward growth) with avoidance of root desiccation (downward growth). © 2018 American Society of Plant Biologists. All Rights Reserved.

Deepwater Fold-and-Thrust Belt Along New Caledonia's Western Margin: Relation to Post-obduction Vertical Motions

NASA Astrophysics Data System (ADS)

Collot, J.; Patriat, M.; Etienne, S.; Rouillard, P.; Soetaert, F.; Juan, C.; Marcaillou, B.; Palazzin, G.; Clerc, C.; Maurizot, P.; Pattier, F.; Tournadour, E.; Sevin, B.; Privat, A.

2017-10-01

Classically, deepwater fold-and-thrust belts are classified in two main types, depending if they result from near- or far-field stresses and the understanding of their driving and triggering mechanism is poorly known. We present a geophysical data set off the western margin of New Caledonia (SW Pacific) that reveals deformed structures of a deepwater fold-and-thrust belt that we interpret as a near-field gravity-driven system, which is not located at a rifted passive margin. The main factor triggering deformation is inferred to be oversteepening of the margin slope by postobduction isostatic rebound. Onshore erosion of abnormally dense obducted material, combined with sediment loading in the adjacent basin, has induced vertical motions that have caused oversteepening of the margin. Detailed morphobathymetric, seismic stratigraphic, and structural analysis reveals that the fold-and-thrust belt extends 200 km along the margin, and 50 km into the New Caledonia Trough. Deformation is rooted at depths greater than 5 km beneath the seafloor, affects an area of 3,500 km2, and involves a sediment volume of approximately 13,000 km3. This deformed belt is organized into an imbricate fan system of faults, and one out-of-sequence thrust fault affects the seabed. The thrust faults are deeply rooted in the basin along a low-angle floor thrust and connected to New Caledonia Island along a major detachment. This study not only provides a better knowledge of the New Caledonia margin but also provides new insight into the mechanisms that trigger deepwater fold-and-thrust belts.

Infrared temperature measurements over bare soil and vegetation - A HAPEX perspective

NASA Technical Reports Server (NTRS)

Carlson, Toby N.; Perry, Eileen M.; Taconet, Odile

1987-01-01

Preliminary analyses of aircraft and ground measurements made in France during the HAPEX experiment show that horizontal radiometric surface temperature variations, as viewed by aircraft, can reflect the vertical profile of soil moisture (soil versus root zone) because of horizontal variations in vegetation density. Analyses based on one day's data show that, although horizontal variations in soil moisture were small, the vertical differences between a dry surface and a wet root zone were large. Horizontal temperature differences between bare soil, corn and oats reflect differences in the fractional vegetation cover, as seen by the radiometer. On the other hand, these horizontal variations in radiometric surface temperature seem to reflect real horizontal variations in surface turbulent energy fluxes.

The Jasmonate Pathway Is a Key Player in Systemically Induced Defense against Root Knot Nematodes in Rice1[C

PubMed Central

Nahar, Kamrun; Kyndt, Tina; De Vleesschauwer, David; Höfte, Monica; Gheysen, Godelieve

2011-01-01

Complex defense signaling pathways, controlled by different hormones, are involved in the reaction of plants to a wide range of biotic and abiotic stress factors. We studied the ability of salicylic acid, jasmonate (JA), and ethylene (ET) to induce systemic defense in rice (Oryza sativa) against the root knot nematode Meloidogyne graminicola. Exogenous ET (ethephon) and JA (methyl jasmonate) supply on the shoots induced a strong systemic defense response in the roots, exemplified by a major up-regulation of pathogenesis-related genes OsPR1a and OsPR1b, while the salicylic acid analog BTH (benzo-1,2,3-thiadiazole-7-carbothioic acid S-methyl ester) was a less potent systemic defense inducer from shoot to root. Experiments with JA biosynthesis mutants and ET-insensitive transgenics showed that ET-induced defense requires an intact JA pathway, while JA-induced defense was still functional when ET signaling was impaired. Pharmacological inhibition of JA and ET biosynthesis confirmed that JA biosynthesis is needed for ET-induced systemic defense, and quantitative real-time reverse transcription-polymerase chain reaction data revealed that ET application onto the shoots strongly activates JA biosynthesis and signaling genes in the roots. All data provided in this study point to the JA pathway to play a pivotal role in rice defense against root knot nematodes. The expression of defense-related genes was monitored in root galls caused by M. graminicola. Different analyzed defense genes were attenuated in root galls caused by the nematode at early time points after infection. However, when the exogenous defense inducers ethephon and methyl jasmonate were supplied to the plant, the nematode was less effective in counteracting root defense pathways, hence making the plant more resistant to nematode infection. PMID:21715672

Automorphosis-like growth in etiolated pea seedlings is induced by the application of chemicals affecting perception of gravistimulation and its signal transduction

NASA Astrophysics Data System (ADS)

Miyamoto, Kensuke; Hoshino, Tomoki; Hitotsubashi, Reiko; Yamashita, Masamichi; Ueda, Junichi

Both microgravity conditions in space and simulated microgravity using a 3-dimensional clinostat resulted in: (1) automorphosis of etiolated pea seedlings, (2) epicotyls bending ca. 45° from the vertical line to the direction away from cotyledons, (3) inhibition of hook formation and (4) alternation of growth direction of roots. These facts indicate that the growth and development of etiolated pea seedlings on earth is under the influence of gravistimulation. Lanthanum and gadolinium ions, blockers of stretch-activated mechanosensitive ion channels, induced automorphosis-like epicotyl bending. Cantharidin, an inhibitor of protein phosphatase, also phenocopied automorphosis-like growth. On the other hand, cytochalasin B, cytochalasin D and brefeldin A did not induce automorphological epicotyl bending and inhibition of hook formation, although these compounds strikingly inhibited elongation of etiolated pea epicotyls. These results strongly suggest that stretch-activated mechanosensitive ion channels are involved in the perception of signals of gravistimuli in plants, and they are transduced by protein phosphorylation and dephosphorylation cascades by changing levels of calcium ions. Possible mechanisms to induce automorphosis-like growth in relation to gravity signals in etiolated pea seedlings are discussed.

Direct estimation of mass flow and diffusion of nitrogen compounds in solution and soil.

PubMed

Oyewole, Olusegun Ayodeji; Inselsbacher, Erich; Näsholm, Torgny

2014-02-01

Plant nutrient uptake from soil is mainly governed by diffusion and transpirationally induced mass flow, but the current methods for assessing the relative importance of these processes are indirect. We developed a microdialysis method using solutions of different osmotic potentials as perfusates to simulate diffusion and mass flow processes, and assessed how induced mass flow affected fluxes of nitrogen (N) compounds in solution and in boreal forest soil. Varying the osmotic potential of perfusates induced vertical fluxes in the direction of the dialysis membranes at rates of between 1 × 10(-8) and 3 × 10(-7)  m s(-1) , thus covering the estimated range of water velocities perpendicular to root surfaces and induced by transpiration. Mass flow increased N fluxes in solution but even more so in soil. This effect was explained by an indirect effect of mass flow on rates of diffusive fluxes, possibly caused by the formation of steeper gradients in concentrations of N compounds from membrane surfaces out in the soil. Our results suggest that transpiration may be an essential driver of plant N acquisition. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

Methane-rich water induces cucumber adventitious rooting through heme oxygenase1/carbon monoxide and Ca(2+) pathways.

PubMed

Cui, Weiti; Qi, Fang; Zhang, Yihua; Cao, Hong; Zhang, Jing; Wang, Ren; Shen, Wenbiao

2015-03-01

Methane-rich water triggered adventitious rooting by regulating heme oxygenase1/carbon monoxide and calcium pathways in cucumber explants. Heme oxygenase1/carbon monoxide (HO1/CO) and calcium (Ca(2+)) were reported as the downstream signals in auxin-induced cucumber adventitious root (AR) formation. Here, we observed that application of methane-rich water (MRW; 80% saturation) obviously induced AR formation in IAA-depleted cucumber explants. To address the universality, we checked adventitious rooting in soybean and mung bean explants, and found that MRW (50 and 10% saturation, respectively) exhibited the similar inducing results. To further determine if the HO1/CO system participated in MRW-induced adventitious rooting, MRW, HO1 inducer hemin, its activity inhibitor zinc protoporphyrin IX (ZnPP), and its catalytic by-products CO, bilirubin, and Fe(2+) were used to detect their effects on cucumber adventitious rooting in IAA-depleted explants. Subsequent results showed that MRW-induced adventitious rooting was blocked by ZnPP and further reversed by 20% saturation CO aqueous solution. However, the other two by-products of HO1, bilirubin and Fe(2+), failed to induce AR formation. Above responses were consistent with the MRW-induced increases of HO1 transcript and corresponding protein level. Further molecular evidence indicted that expression of marker genes, including auxin signaling-related genes and cell cycle regulatory genes, were modulated by MRW alone but blocked by the cotreatment with ZnPP, the latter of which could be significantly rescued by the addition of CO. By using the Ca(2+)-channel blocker and Ca(2+) chelator, the involvement of Ca(2+) pathway in MRW-induced adventitious rooting was also suggested. Together, our results indicate that MRW might serve as a stimulator of adventitious rooting, which was partially mediated by HO1/CO and Ca(2+) pathways.

Nitric oxide mediates alginate oligosaccharides-induced root development in wheat (Triticum aestivum L.).

PubMed

Zhang, Yunhong; Liu, Hang; Yin, Heng; Wang, Wenxia; Zhao, Xiaoming; Du, Yuguang

2013-10-01

Alginate oligosaccharides (AOS), which are marine oligosaccharides, are involved in regulating plant root growth, but the promotion mechanism for AOS remains unclear. Here, AOS (10-80 mg L(-1)) were found to induce the generation of nitric oxide (NO) in the root system of wheat (Triticum aestivum L.), which promoted the formation and elongation of wheat roots in a dose-dependent manner. NO inhibitors suggested that nitrate reductase (NR), rather than nitric oxide synthase (NOS), was essential for AOS-induced root development. Further studies confirmed that AOS-induced NO generation in wheat roots by up-regulating the gene expression and enzyme activity of NR at the post-transcriptional level. The anatomy and RT-PCR results showed that AOS accelerated the division and growth of stele cells, leading to an increase in the ratio of stele area to root transverse area. This could be inhibited by the NR inhibitor, sodium tungstate, which indicated that NO catalyzed by the NR was involved in AOS regulation of root development. Taken together, in the early stage of AOS-induced root development, NO generation was a novel mechanism by which AOS regulated plant growth. The results also showed that this marine resource could be widely used for crop development. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Hydrologic Controls on Shallow Landslide Location, Size, and Shape

NASA Astrophysics Data System (ADS)

Bellugi, D.; Milledge, D.; Perron, T.; McKean, J. A.; Dietrich, W.; Rulli, M.

2012-12-01

Shallow landslides, typically involving just the soil mantle, are principally controlled by topography, soil and root strengths, and soil thickness, and are typically triggered by storm-induced increases in pore water pressure. The response of a landscape to landslide-triggering storms will thus depend on factors such as rainfall totals, storm intensity and duration, and antecedent moisture conditions. The two dominant mechanisms that generate high pore water pressures at a point are topographically-steered lateral subsurface flow (over timescales of days to weeks), and rapid vertical infiltration (over timescales of minutes to hours). We aim to understand the impact of different storm characteristics and hydrologic regimes on shallow landslide location, size, and shape. We have developed a regional-scale model, which applies a low-parameter grid-based multi-dimensional slope stability model within a novel search algorithm, to generate discrete landslide predictions. This model shows that the spatial organization of parameters such as root strength and pore water pressure has a strong control on shallow landslide location, size, and shape. We apply this model to a field site near Coos Bay, OR, where a ten-year landslide inventory has been mapped onto high-resolution topographic data. Our model predicts landslide size generally increases with increasing rainfall intensity, except when root strength is extremely high and pore pressures are topographically steered. The distribution of topographic index values (the ratios of contributing area to slope) of predicted landslides is a clear signature of the pore water pressure generation mechanism: as laterally dominated flow increases, landslides develop in locations with lower slopes and higher contributing areas; in contrast, in the case of vertically-dominated pore pressure rise, landslides are consistently found in locations with higher slopes and lower contributing areas. While in both cases landslides are found in the hollows, where the soils are sufficiently deep to overcome the effects of root strength, in the laterally-dominated case they are predicted to occur further down the hollows (which matches field observations). The size distribution of landslides is better predicted in our model when vertical infiltration dominates, but the observed distribution of topographic index values follows that predicted when lateral flow dominates. This suggests that both mechanisms must be taken into account in order to capture both location and size of shallow landslides (consistent with field observations). These results suggest that this modeling approach could allow us to use observed landslide locations and geometries to infer the dominant hydrologic triggering mechanisms. Furthermore, as the spatial and temporal resolution of precipitation forecasting improves, this model will enable us to more accurately predict both location and size of shallow landslides.

Hairy root culture in a liquid-dispersed bioreactor: characterization of spatial heterogeneity.

PubMed

Williams, G R; Doran, P M

2000-01-01

A liquid-dispersed reactor equipped with a vertical mesh cylinder for inoculum support was developed for culture of Atropa belladonna hairy roots. The working volume of the culture vessel was 4.4 L with an aspect ratio of 1.7. Medium was dispersed as a spray onto the top of the root bed, and the roots grew radially outward from the central mesh cylinder to the vessel wall. Significant benefits in terms of liquid drainage and reduced interstitial liquid holdup were obtained using a vertical rather than horizontal support structure for the biomass and by operating the reactor with cocurrent air and liquid flow. With root growth, a pattern of spatial heterogeneity developed in the vessel. Higher local biomass densities, lower volumes of interstitial liquid, lower sugar concentrations, and higher root atropine contents were found in the upper sections of the root bed compared with the lower sections, suggesting a greater level of metabolic activity toward the top of the reactor. Although gas-liquid oxygen transfer to the spray droplets was very rapid, there was evidence of significant oxygen limitations in the reactor. Substantial volumes of non-free-draining interstitial liquid accumulated in the root bed. Roots near the bottom of the vessel trapped up to 3-4 times their own weight in liquid, thus eliminating the advantages of improved contact with the gas phase offered by liquid-dispersed culture systems. Local nutrient and product concentrations in the non-free-draining liquid were significantly different from those in the bulk medium, indicating poor liquid mixing within the root bed. Oxygen enrichment of the gas phase improved neither growth nor atropine production, highlighting the greater importance of liquid-solid compared with gas-liquid oxygen transfer resistance. The absence of mechanical or pneumatic agitation and the tendency of the root bed to accumulate liquid and impede drainage were identified as the major limitations to reactor performance. Improved reactor operating strategies and selection or development of root lines offering minimal resistance to liquid flow and low liquid retention characteristics are possible solutions to these problems.

Plasma membrane H(+)-ATPase is involved in methyl jasmonate-induced root hair formation in lettuce (Lactuca sativa L.) seedlings.

PubMed

Zhu, Changhua; Yang, Na; Ma, Xiaoling; Li, Guijun; Qian, Meng; Ng, Denny; Xia, Kai; Gan, Lijun

2015-06-01

Our results show that methyl jasmonate induces plasma membrane H (+) -ATPase activity and subsequently influences the apoplastic pH of trichoblasts to maintain a cell wall pH environment appropriate for root hair development. Root hairs, which arise from root epidermal cells, are tubular structures that increase the efficiency of water absorption and nutrient uptake. Plant hormones are critical regulators of root hair development. In this study, we investigated the regulatory role of the plasma membrane (PM) H(+)-ATPase in methyl jasmonate (MeJA)-induced root hair formation. We found that MeJA had a pronounced effect on the promotion of root hair formation in lettuce seedlings, but that this effect was blocked by the PM H(+)-ATPase inhibitor vanadate. Furthermore, MeJA treatment increased PM H(+)-ATPase activity in parallel with H(+) efflux from the root tips of lettuce seedlings and rhizosphere acidification. Our results also showed that MeJA-induced root hair formation was accompanied by hydrogen peroxide accumulation. The apoplastic acidification acted in concert with reactive oxygen species to modulate root hair formation. Our results suggest that the effect of MeJA on root hair formation is mediated by modulation of PM H(+)-ATPase activity.

Root induced changes of effective 1D hydraulic properties in a soil column.

PubMed

Scholl, P; Leitner, D; Kammerer, G; Loiskandl, W; Kaul, H-P; Bodner, G

Roots are essential drivers of soil structure and pore formation. This study aimed at quantifying root induced changes of the pore size distribution (PSD). The focus was on the extent of clogging vs. formation of pores during active root growth. Parameters of Kosugi's lognormal PSD model were determined by inverse estimation in a column experiment with two cover crops (mustard, rye) and an unplanted control. Pore dynamics were described using a convection-dispersion like pore evolution model. Rooted treatments showed a wider range of pore radii with increasing volumes of large macropores >500 μm and micropores <2.5 μm, while fine macropores, mesopores and larger micropores decreased. The non-rooted control showed narrowing of the PSD and reduced porosity over all radius classes. The pore evolution model accurately described root induced changes, while structure degradation in the non-rooted control was not captured properly. Our study demonstrated significant short term root effects with heterogenization of the pore system as dominant process of root induced structure formation. Pore clogging is suggested as a partial cause for reduced pore volume. The important change in micro- and large macropores however indicates that multiple mechanic and biochemical processes are involved in root-pore interactions.

Orthodontic tooth movement and root resorption in ovariectomized rats treated by systemic administration of zoledronic acid.

PubMed

Sirisoontorn, Irin; Hotokezaka, Hitoshi; Hashimoto, Megumi; Gonzales, Carmen; Luppanapornlarp, Suwannee; Darendeliler, M Ali; Yoshida, Noriaki

2012-05-01

The effect of zoledronic acid, a potent and novel bisphosphonate, on tooth movement and orthodontically induced root resorption in osteoporotic animals systemically treated with zoledronic acid as similarly used in postmenopausal patients has not been elucidated. Therefore, this study was undertaken. Fifteen 10-week-old female Wistar rats were divided into 3 groups: ovariectomy, ovariectomy + zoledronic acid, and control. Only the ovariectomy and ovariectomy + zoledronic acid groups underwent ovariectomies. Two weeks after the ovariectomy, zoledronic acid was administered only to the ovariectomy + zoledronic acid group. Four weeks after the ovariectomy, 25-g nickel-titanium closed-coil springs were applied to observe tooth movement and orthodontically induced root resorption. There were significant differences in the amounts of tooth movement and orthodontically induced root resorption between the ovariectomy and the control groups, and also between the ovariectomy and the ovariectomy + zoledronic acid groups. There was no statistically significant difference in tooth movement and orthodontically induced root resorption between the ovariectomy + zoledronic acid and the control groups. Zoledronic acid inhibited significantly more tooth movement and significantly reduced the severity of orthodontically induced root resorption in the ovariectomized rats. The ovariectomy + zoledronic acid group showed almost the same results as did the control group in both tooth movement and orthodontically induced root resorption. Zoledronic acid inhibits excessive orthodontic tooth movement and also reduces the risk of severe orthodontically induced root resorption in ovariectomized rats. Copyright © 2012 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

WETLAND RESTORATION AND REMEDIATION IN SOUTHWEST LOUISIANA MARSHES: A STUDY OF SOIL ELEVATION, VERTICAL ACCRETION, SHALLOW SUBSIDENCE AND ROOT ZONE INFLUENCES IN MARSHES RESTORED USING A VARIETY OF TECHNIQUES

EPA Science Inventory

For Project 1, we will continue sampling of all restoration sites on a quarterly basis. We also will present findings at the 2003 Society of Wetland Scientists Meeting. We will prepare a final data set for a peer-reviewed journal publication. Below-ground root zone...

Zoom Reconstruction Tool: Evaluation of Image Quality and Influence on the Diagnosis of Root Fracture.

PubMed

Queiroz, Polyane Mazucatto; Santaella, Gustavo Machado; Capelozza, Ana Lúcia Alvares; Rosalen, Pedro Luiz; Freitas, Deborah Queiroz; Haiter-Neto, Francisco

2018-04-01

This study evaluated the image quality and the diagnosis of root fractures when using the Zoom Reconstruction tool (J Morita, Kyoto, Japan). A utility wax phantom with a metal sample inside was used for objective evaluation, and a mandible with 27 single-rooted teeth (with and without obturation and with and without vertical or horizontal fractures) was used for diagnostic evaluation. The images were acquired in 3 protocols: protocol 1, field of view (FOV) of 4 × 4 cm and a voxel size of 0.08 mm; protocol 2, FOV of 10 × 10 cm and a voxel size of 0.2 mm; and protocol 3, Zoom Reconstruction of images from protocol 2 (FOV of 4 × 4 cm and a voxel size of 0.08 mm). The objective evaluation was achieved by measuring the image noise, and the diagnosis of fractures was performed by 3 evaluators. The area under the receiver operating characteristic curve was used to calculate accuracy, and analysis of variance compared the accuracy and image quality of the protocols. Regarding quality, protocol 1 was superior to protocol 2 (P < .0001) and Zoom Reconstruction (P < .0001). Additionally, images of protocol 2 presented less noise than the Zoom Reconstruction image (P < .0001); however, for diagnosis, Zoom Reconstruction was superior in relation to protocol 2 (P = .011) and did not differ from protocol 1 (P = .228) for the diagnosis of a vertical root fracture in filled teeth. The Zoom Reconstruction tool allows better accuracy for vertical root fracture detection in filled teeth, making it possible to obtain a higher-resolution image from a lower-resolution examination without having to expose the patient to more radiation. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Intentional replantation of adhesively reattached vertically fractured maxillary single-rooted teeth.

PubMed

Nizam, N; Kaval, M E; Gürlek, Ö; Atila, A; Çalışkan, M K

2016-03-01

To evaluate the clinical outcomes of intentionally replanted maxillary single-rooted teeth with vertical root fractures (VRFs) after being repaired extraorally using 4-methacryloxyethyl trimellitate anhydride/methacrylate-tri-n-butyl borane (4-META/MMA-TBB) resin cement. Twenty-one root filled maxillary single-rooted teeth with VRFs were evaluated. After atraumatic extraction, fractured fragments were adhesively cemented. The teeth were then replanted and splinted to the neighbouring teeth for 2 weeks. Plaque index (PI), gingival index (GI), probing depth (PD) and clinical attachment level (CAL) were assessed at baseline, 6 and 12 months, and radiographic evaluations were made using PAI scores at baseline and 12 months. Mobility was evaluated using periotest values (PTV) at baseline, 1, 3, 6 and 12 months. Replanted teeth, contralateral teeth (control teeth) and adjacent teeth were analysed statistically using repeated measures one-way anova, unpaired t-tests and Wilcoxon matched-pairs signed-rank tests. Two teeth were extracted in the first month after surgery. PI, GI, CAL and PD scores of the replanted teeth were significantly lower at 6 month (P < 0.0001 for all) and 12 month (P < 0.0001 for all) postoperatively when compared to baseline, but the values were not significantly different from those of the control and adjacent teeth. PTV of the test teeth increased significantly (P < 0.0001) after the intervention and decreased to baseline levels by month 12. PTVs were significantly higher (P < 0.05) at baseline, 1, 3 and 6 months in the test teeth when compared with the control teeth, but were not significantly different at month 12. PAI scores of teeth with VRF were significantly lower (P < 0.05) at 12 months compared with baseline. Adhesive cementation and intentional replantation were an effective treatment modality for this group of vertically fractured maxillary single-rooted teeth. The clinical periodontal parameters decrease by month 6, and the mobility returned to the physiological limits of natural teeth 12 months after replantation. © 2015 International Endodontic Journal. Published by John Wiley & Sons Ltd.

How roots perceive and respond to gravity

NASA Technical Reports Server (NTRS)

Moore, R.; Evans, M. L.

1986-01-01

Graviperception by plant roots is believed to occur via the sedimentation of amyloplasts in columella cells of the root cap. This physical stimulus results in an accumulation of calcium on the lower side of the cap, which in turn induces gravicurvature. In this paper we present a model for root gravitropism integrating gravity-induced changes in electrical potential, cytochemical localization of calcium in cells of gravistimulated roots, and the interdependence of calcium and auxin movement. Key features of the model are that 1) gravity-induced redistribution of calcium is an early event in the transduction mechanism, and 2) apoplastic movement of calcium through the root-cap mucilage may be an important component of the pathway for calcium movement.

Control of gravitropic orientation. I. Non-vertical orientation by primary roots of maize results from decay of competence for orthogravitropic induction

NASA Technical Reports Server (NTRS)

LaMotte, Clifford E.; Pickard, Barbara G.

2004-01-01

Plant organs may respond to gravity by vertical (orthogravitropic), oblique (plagiogravitropic) or horizontal (diagravitropic) growth. Primary roots of maize (Zea mays L.) provide a good system for studying such behaviours because they are reportedly capable of displaying all three responses. In current work using maize seedlings of the Silver Queen cultivar, stabilisation of growth at an oblique orientation was commonplace. Hypothetically, plagiogravitropism may be accomplished either by a process we call graded orthogravitropism or by hunting about a sensed non-vertical setpoint. In graded orthotropism primary bending is unidirectional and depends on facilitative stimuli that determine its extent. The hallmark of the setpoint mechanism is restorative curvature of either sign following a displacement; both diagravitropism and orthogravitropism are based on setpoints. Roots settled in a plagiogravitropic orientation were tested with various illumination and displacement protocols designed to distinguish between these two hypotheses. The tests refuted the setpoint hypothesis and supported that of graded orthotropism. No evidence of diagravitropism could be found, thus, earlier claims were likely based on inadequately controlled observations of graded orthotropism. We propose that orthotropism is graded by the sequential action of dual gravity receptors: induction of a vectorial gravitropic response requires gravitational induction of a separate facilitative response, whose decay in the absence of fresh stimuli can brake gravitropism at plagiotropic angles.

Tomato root growth, gravitropism, and lateral development: correlation with auxin transport

NASA Technical Reports Server (NTRS)

Muday, G. K.; Haworth, P.

1994-01-01

Tomato (Lycopersicon esculentum, Mill.) roots were analyzed during growth on agar plates. Growth of these roots was inhibited by the auxin transport inhibitors naphthylphthalamic acid (NPA) and semicarbazone derivative I (SCB-1). The effect of auxin transport inhibitors on root gravitropism was analyzed by measurement of the angle of gravitropic curvature after the roots were reoriented 90 degrees from the vertical. NPA and SCB-1 abolished both the response of these roots to gravity and the formation of lateral roots, with SCB-1 being the more effective at inhibition. Auxins also inhibited root growth. Both auxins tested has a slight effect on the gravity response, but this effect is probably indirect, since auxins reduced the growth rate. Auxins also stimulated lateral root growth at concentration where primary root growth was inhibited. When roots were treated with both IAA and NPA simultaneously, a cumulative inhibition of root growth was found. When both compounds were applied together, analysis of gravitropism and lateral root formation indicated that the dominant effect was exerted by auxin transport inhibitors. Together, these data suggest a model for the role of auxin transport in controlling both primary and lateral root growth.

Smooth and vertical facet formation for AlGaN-based deep-UV laser diodes.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bogart, Katherine Huderle Andersen; Shul, Randy John; Stevens, Jeffrey

2008-10-01

Using a two-step method of plasma and wet chemical etching, we demonstrate smooth, vertical facets for use in Al{sub x} Ga{sub 1-x} N-based deep-ultraviolet laser-diode heterostructures where x = 0 to 0.5. Optimization of plasma-etching conditions included increasing both temperature and radiofrequency (RF) power to achieve a facet angle of 5 deg from vertical. Subsequent etching in AZ400K developer was investigated to reduce the facet surface roughness and improve facet verticality. The resulting combined processes produced improved facet sidewalls with an average angle of 0.7 deg from vertical and less than 2-nm root-mean-square (RMS) roughness, yielding an estimated reflectivity greatermore » than 95% of that of a perfectly smooth and vertical facet.« less

Comparative effectiveness of metal ions in inducing curvature of primary roots of Zea mays

NASA Technical Reports Server (NTRS)

Hasenstein, K. H.; Evans, M. L.; Stinemetz, C. L.; Moore, R.; Fondren, W. M.; Koon, E. C.; Higby, M. A.; Smucker, A. J.

1988-01-01

We used five cultivars of Zea mays (Bear Hybrid WF9 * 38MS, B73 * Missouri 17, Yellow Dent, Merit, and Great Lakes Hybrid 422) to reinvestigate the specificity of metal ions for inducing root curvature. Of 17 cations tested, 6 (Al3+, Ba2+, Ca2+, Cd2+, Cu2+, Zn2+) induced curvature. Roots curved away from Al3+, Ba2+, and Cd2+. Roots curved away from low (0.1 millimolar) concentrations of Cu2+ but toward higher (1-5 millimolar) concentrations. Roots initially curved away from Zn2+ but the direction of the subsequent curvature was unpredictable. In most cases, roots of all cultivars curved towards calcium. However, in some tests there was no response to calcium or even (especially in the cultivars Merit and B73 * Missouri 17) substantial curvature away from calcium. The results indicate that the induction of root curvature is not specific for calcium. The results are discussed relative to the possible role of calmodulin as a mediator of ion-induced root curvature.

Comparative Effectivness of Metal Ions in Inducing Curvature of Primary Roots of Zea mays1

PubMed Central

Hasenstein, Karl Heinz; Evans, Michael L.; Stinemetz, Charles L.; Moore, Randy; Fondren, W. Mark; Koon, E. Colin; Higby, Mary A.; Smucker, Alvin J. M.

1988-01-01

We used five cultivars of Zea mays (Bear Hybrid WF9 * 38MS, B73 * Missouri 17, Yellow Dent, Merit, and Great Lakes Hybrid 422) to reinvestigate the specificity of metal ions for inducing root curvature. Of 17 cations tested, 6 (Al3+, Ba2+, Ca2+, Cd2+, Cu2+, Zn2+) induced curvature. Roots curved away from Al3+, Ba2+, and Cd2+. Roots curved away from low (0.1 millimolar) concentrations of Cu2+ but toward higher (1-5 millimolar) concentrations. Roots initially curved away from Zn2+ but the direction of the subsequent curvature was unpredictable. In most cases, roots of all cultivars curved towards calcium. However, in some tests there was no response to calcium or even (especially in the cultivars Merit and B73 * Missouri 17) substantial curvature away from calcium. The results indicate that the induction of root curvature is not specific for calcium. The results are discussed relative to the possible role of calmodulin as a mediator of ion-induced root curvature. PMID:11538239

An NADPH Oxidase RBOH Functions in Rice Roots during Lysigenous Aerenchyma Formation under Oxygen-Deficient Conditions

PubMed Central

Yoshioka, Miki; Fukazawa, Aya; Nishizawa, Naoko K.

2017-01-01

Reactive oxygen species (ROS) produced by the NADPH oxidase, respiratory burst oxidase homolog (RBOH), trigger signal transduction in diverse biological processes in plants. However, the functions of RBOH homologs in rice (Oryza sativa) and other gramineous plants are poorly understood. Ethylene induces the formation of lysigenous aerenchyma, which consists of internal gas spaces created by programmed cell death of cortical cells, in roots of gramineous plants under oxygen-deficient conditions. Here, we report that, in rice, one RBOH isoform (RBOHH) has a role in ethylene-induced aerenchyma formation in roots. Induction of RBOHH expression under oxygen-deficient conditions was greater in cortical cells than in cells of other root tissues. In addition, genes encoding group I calcium-dependent protein kinases (CDPK5 and CDPK13) were strongly expressed in root cortical cells. Coexpression of RBOHH with CDPK5 or CDPK13 induced ROS production in Nicotiana benthamiana leaves. Inhibitors of RBOH activity or cytosolic calcium influx suppressed ethylene-induced aerenchyma formation. Moreover, knockout of RBOHH by CRISPR/Cas9 reduced ROS accumulation and inducible aerenchyma formation in rice roots. These results suggest that RBOHH-mediated ROS production, which is stimulated by CDPK5 and/or CDPK13, is essential for ethylene-induced aerenchyma formation in rice roots under oxygen-deficient conditions. PMID:28351990

Alteration of cell-wall porosity is involved in osmotic stress-induced enhancement of aluminium resistance in common bean (Phaseolus vulgaris L.)

PubMed Central

Yang, Zhong-Bao; Eticha, Dejene; Rao, Idupulapati Madhusudana; Horst, Walter Johannes

2010-01-01

Aluminium (Al) toxicity and drought are the two major abiotic stress factors limiting common bean production in the tropics. Using hydroponics, the short-term effects of combined Al toxicity and drought stress on root growth and Al uptake into the root apex were investigated. In the presence of Al stress, PEG 6000 (polyethylene glycol)-induced osmotic (drought) stress led to the amelioration of Al-induced inhibition of root elongation in the Al-sensitive genotype VAX 1. PEG 6000 (>> PEG 1000) treatment greatly decreased Al accumulation in the 1 cm root apices even when the roots were physically separated from the PEG solution using dialysis membrane tubes. Upon removal of PEG from the treatment solution, the root tips recovered from osmotic stress and the Al accumulation capacity was quickly restored. The PEG-induced reduction of Al accumulation was not due to a lower phytotoxic Al concentration in the treatment solution, reduced negativity of the root apoplast, or to enhanced citrate exudation. Also cell-wall (CW) material isolated from PEG-treated roots showed a low Al-binding capacity which, however, was restored after destroying the physical structure of the CW. The comparison of the Al3+, La3+, Sr2+, and Rb+ binding capacity of the intact root tips and the isolated CW revealed the specificity of the PEG 6000 effect for Al. This could be due to the higher hydrated ionic radius of Al3+ compared with other cations (Al3+ >> La3+ > Sr2+ > Rb+). In conclusion, the results provide circumstantial evidence that the osmotic stress-inhibited Al accumulation in root apices and thus reduced Al-induced inhibition of root elongation in the Al-sensitive genotype VAX 1 is related to the alteration of CW porosity resulting from PEG 6000-induced dehydration of the root apoplast. PMID:20511277

Nitric oxide is the shared signalling molecule in phosphorus- and iron-deficiency-induced formation of cluster roots in white lupin (Lupinus albus)

PubMed Central

Meng, Zhi Bin; Chen, Li Qian; Suo, Dong; Li, Gui Xin; Tang, Cai Xian; Zheng, Shao Jian

2012-01-01

Background and Aims Formation of cluster roots is one of the most specific root adaptations to nutrient deficiency. In white lupin (Lupinus albus), cluster roots can be induced by phosphorus (P) or iron (Fe) deficiency. The aim of the present work was to investigate the potential shared signalling pathway in P- and Fe-deficiency-induced cluster root formation. Methods Measurements were made of the internal concentration of nutrients, levels of nitric oxide (NO), citrate exudation and expression of some specific genes under four P × Fe combinations, namely (1) 50 µm P and 10 µm Fe (+P + Fe); (2) 0 P and 10 µm Fe (–P + Fe); (3) 50 µm P and 0 Fe (+P–Fe); and (4) 0 P and 0 Fe (–P–Fe), and these were examined in relation to the formation of cluster roots. Key Results The deficiency of P, Fe or both increased the cluster root number and cluster zones. It also enhanced NO accumulation in pericycle cells and rootlet primordia at various stages of cluster root development. The formation of cluster roots and rootlet primordia, together with the expression of LaSCR1 and LaSCR2 which is crucial in cluster root formation, were induced by the exogenous NO donor S-nitrosoglutathione (GSNO) under the +P + Fe condition, but were inhibited by the NO-specific endogenous scavenger 2-(4-carboxyphenyl)-4, 4, 5, 5-tetramethylimidazoline-1-oxyl- 3-oxide (cPTIO) under –P + Fe, +P–Fe and –P–Fe conditions. However, cluster roots induced by an exogenous supply of the NO donor did not secrete citrate, unlike those formed under –P or –Fe conditions. Conclusions NO plays an important role in the shared signalling pathway of the P- and Fe-deficiency-induced formation of cluster roots in white lupin. PMID:22351487

Importance of Vertical Coupling in Agricultural Models on Assimilation of Satellite-derived Soil Moisture

NASA Astrophysics Data System (ADS)

Mladenova, I. E.; Crow, W. T.; Teng, W. L.; Doraiswamy, P.

2010-12-01

Crop yield in crop production models is simulated as a function of weather, ground conditions and management practices and it is driven by the amount of nutrients, heat and water availability in the root-zone. It has been demonstrated that assimilation of satellite-derived soil moisture data has the potential to improve the model root-zone soil water (RZSW) information. However, the satellite estimates represent the moisture conditions of the top 3 cm to 5 cm of the soil profile depending on system configuration and surface conditions (i.e. soil wetness, density of the canopy cover, etc). The propagation of this superficial information throughout the profile will depend on the model physics. In an Ensemble Kalman Filter (EnKF) data assimilation system, as the one examined here, the update of each soil layer is done through the Kalman Gain, K. K is a weighing factor that determines how much correction will be performed on the forecasts. Furthermore, K depends on the strength of the correlation between the surface and the root-zone soil moisture; the stronger this correlation is, the more observations will impact the analysis. This means that even if the satellite-derived product has higher sensitivity and accuracy as compared to the model estimates, the improvement of the RZSW will be negligible if the surface-root zone coupling is weak, where the later is determined by the model subsurface physics. This research examines: (1) the strength of the vertical coupling in the Environmental Policy Integrated Climate (EPIC) model over corn and soybeans covered fields in Iowa, US, (2) the potential to improve EPIC RZSW information through assimilation of satellite soil moisture data derived from the Advanced Microwave Scanning Radiometer (AMSR-E) and (3) the impact of the vertical coupling on the EnKF performance.

Proper PIN1 Distribution Is Needed for Root Negative Phototropism in Arabidopsis

PubMed Central

Zhang, Kun-Xiao; Xu, Heng-Hao; Gong, Wen; Jin, Yan; Shi, Ya-Ya; Yuan, Ting-Ting; Li, Juan; Lu, Ying-Tang

2014-01-01

Plants can be adapted to the changing environments through tropic responses, such as light and gravity. One of them is root negative phototropism, which is needed for root growth and nutrient absorption. Here, we show that the auxin efflux carrier PIN-FORMED (PIN) 1 is involved in asymmetric auxin distribution and root negative phototropism. In darkness, PIN1 is internalized and localized to intracellular compartments; upon blue light illumination, PIN1 relocalize to basal plasma membrane in root stele cells. The shift of PIN1 localization induced by blue light is involved in asymmetric auxin distribution and root negative phototropic response. Both blue-light-induced PIN1 redistribution and root negative phototropism is mediated by a BFA-sensitive trafficking pathway and the activity of PID/PP2A. Our results demonstrate that blue-light-induced PIN1 redistribution participate in asymmetric auxin distribution and root negative phototropism. PMID:24465665

Proper PIN1 distribution is needed for root negative phototropism in Arabidopsis.

PubMed

Zhang, Kun-Xiao; Xu, Heng-Hao; Gong, Wen; Jin, Yan; Shi, Ya-Ya; Yuan, Ting-Ting; Li, Juan; Lu, Ying-Tang

2014-01-01

Plants can be adapted to the changing environments through tropic responses, such as light and gravity. One of them is root negative phototropism, which is needed for root growth and nutrient absorption. Here, we show that the auxin efflux carrier PIN-FORMED (PIN) 1 is involved in asymmetric auxin distribution and root negative phototropism. In darkness, PIN1 is internalized and localized to intracellular compartments; upon blue light illumination, PIN1 relocalize to basal plasma membrane in root stele cells. The shift of PIN1 localization induced by blue light is involved in asymmetric auxin distribution and root negative phototropic response. Both blue-light-induced PIN1 redistribution and root negative phototropism is mediated by a BFA-sensitive trafficking pathway and the activity of PID/PP2A. Our results demonstrate that blue-light-induced PIN1 redistribution participate in asymmetric auxin distribution and root negative phototropism.

Inhibition of ethylene production by putrescine alleviates aluminium-induced root inhibition in wheat plants.

PubMed

Yu, Yan; Jin, Chongwei; Sun, Chengliang; Wang, Jinghong; Ye, Yiquan; Zhou, Weiwei; Lu, Lingli; Lin, Xianyong

2016-01-08

Inhibition of root elongation is one of the most distinct symptoms of aluminium (Al) toxicity. Although putrescine (Put) has been identified as an important signaling molecule involved in Al tolerance, it is yet unknown how Put mitigates Al-induced root inhibition. Here, the possible mechanism was investigated by using two wheat genotypes differing in Al resistance: Al-tolerant Xi Aimai-1 and Al-sensitive Yangmai-5. Aluminium caused more root inhibition in Yangmai-5 and increased ethylene production at the root apices compared to Xi Aimai-1, whereas the effects were significantly reversed by ethylene biosynthesis inhibitors. The simultaneous exposure of wheat seedlings to Al and ethylene donor, ethephon, or ethylene biosynthesis precursor, 1-aminocyclopropane-1-carboxylic acid (ACC), increased ethylene production and aggravated root inhibition, which was more pronounced in Xi Aimai-1. In contrast, Put treatment decreased ethylene production and alleviated Al-induced root inhibition in both genotypes, and the effects were more conspicuous in Yangmai-5. Furthermore, our results indicated that Al-induced ethylene production was mediated by ACC synthase (ACS) and ACC oxidase, and that Put decreased ethylene production by inhibiting ACS. Altogether, these findings indicate that ethylene is involved in Al-induced root inhibition and this process could be alleviated by Put through inhibiting ACS activity.

Root reinforcement and its contribution to slope stability in the Western Ghats of Kerala, India

NASA Astrophysics Data System (ADS)

Lukose Kuriakose, Sekhar; van Beek, L. P. H.

2010-05-01

The Western Ghats of Kerala, India is prone to shallow landslides and consequent debris flows. An earlier study (Kuriakose et al., DOI:10.1002/esp.1794) with limited data had already demonstrated the possible effects of vegetation on slope hydrology and stability. Spatially distributed root cohesion is one of the most important data necessary to assess the effects of anthropogenic disturbances on the probability of shallow landslide initiation, results of which are reported in sessions GM6.1 and HS13.13/NH3.16. Thus it is necessary to the know the upper limits of reinforcement that the roots are able to provide and its spatial and vertical distribution in such an anthropogenically intervened terrain. Root tensile strength and root pull out tests were conducted on nine species of plants that are commonly found in the region. They are 1) Rubber (Hevea Brasiliensis), 2) Coconut Palm (Cocos nucifera), 3) Jackfruit trees (Artocarpus heterophyllus), 4) Teak (Tectona grandis), 5) Mango trees (Mangifera indica), 6) Lemon grass (Cymbopogon citratus), 7) Gambooge (Garcinia gummi-gutta), 8) Coffee (Coffea Arabica) and 9) Tea (Camellia sinensis). About 1500 samples were collected of which only 380 could be tested (in the laboratory) due to breakage of roots during the tests. In the successful tests roots failed in tension. Roots having diameters between 2 mm and 12 mm were tested. Each sample tested had a length of 15 cm. Root pull out tests were conducted in the field. Root tensile strength vs root diameter, root pull out strength vs diameter, root diameter vs root depth and root count vs root depth relationships were derived. Root cohesion was computed for nine most dominant plants in the region using the perpendicular root model of Wu et al. (1979) modified by Schimidt et al. (2001). A soil depth map was derived using regression kriging as suggested by Kuriakose et al., (doi:10.1016/j.catena.2009.05.005) and used along with the land use map of 2008 to distribute the computed root tensile strength both vertically and spatially. Root cohesion varies significantly with the type of land use and the depth of soil. The computation showed that a maximum root reinforcement of 40 kPa was available in the first 30 cm of soil while exponentially decreased with depth to just about 3 kPa at 3 m depth. Mixed crops land use unit had the maximum root cohesion while fallow land, degraded forest and young rubber plantation had the lowest root reinforcement. These are the upper limits of root reinforcement that the vegetation can provide. When the soil is saturated, the bond between soil and roots reduces and thus the applicable root reinforcement is limited by the root pullout strength. Root reinforcement estimated from pullout strength vs diameter relationships was significantly lower than those estimated from tensile strength vs diameter relationships.

Molecular Transducers from Roots Are Triggered in Arabidopsis Leaves by Root-Knot Nematodes for Successful Feeding Site Formation: A Conserved Post-Embryogenic De novo Organogenesis Program?

PubMed Central

Olmo, Rocío; Cabrera, Javier; Moreno-Risueno, Miguel A.; Fukaki, Hidehiro; Fenoll, Carmen; Escobar, Carolina

2017-01-01

Root-knot nematodes (RKNs; Meloidogyne spp.) induce feeding cells (giant cells; GCs) inside a pseudo-organ (gall) from still unknown root cells. Understanding GCs ontogeny is essential to the basic knowledge of RKN–plant interaction and to discover novel and effective control strategies. Hence, we report for the first time in a model plant, Arabidopsis, molecular, and cellular features concerning ectopic de novo organogenesis of RKNs GCs in leaves. RKNs induce GCs in leaves with irregular shape, a reticulated cytosol, and fragmented vacuoles as GCs from roots. Leaf cells around the nematode enter G2-M shown by ProCycB1;1:CycB1;1(NT)-GUS expression, consistent to multinucleated GCs. In addition, GCs nuclei present irregular and varied sizes. All these characteristics mentioned, being equivalent to GCs in root-galls. RKNs complete their life cycle forming a gall/callus-like structure in the leaf vascular tissues resembling auxin-induced callus with an auxin-response maxima, indicated by high expression of DR5::GUS that is dependent on leaf auxin-transport. Notably, induction of leaves calli/GCs requires molecular components from roots crucial for lateral roots (LRs), auxin-induced callus and root-gall formation, i.e., LBD16. Hence, LBD16 is a xylem pole pericycle specific and local marker in LR primordia unexpectedly induced locally in the vascular tissue of leaves after RKN infection. LBD16 is also fundamental for feeding site formation as RKNs could not stablish in 35S::LBD16-SRDX leaves, and likely it is also a conserved molecular hub between biotic and developmental signals in Arabidopsis either in roots or leaves. Moreover, RKNs induce the ectopic development of roots from leaf and root-galls, also formed in mutants compromised in LR formation, arf7/arf19, slr, and alf4. Therefore, nematodes must target molecular signatures to induce post-embryogenic de novo organogenesis through the LBD16 callus formation pathway partially different from those prevalent during normal LR development. PMID:28603536

Molecular Transducers from Roots Are Triggered in Arabidopsis Leaves by Root-Knot Nematodes for Successful Feeding Site Formation: A Conserved Post-Embryogenic De novo Organogenesis Program?

PubMed

Olmo, Rocío; Cabrera, Javier; Moreno-Risueno, Miguel A; Fukaki, Hidehiro; Fenoll, Carmen; Escobar, Carolina

2017-01-01

Root-knot nematodes (RKNs; Meloidogyne spp.) induce feeding cells (giant cells; GCs) inside a pseudo-organ (gall) from still unknown root cells. Understanding GCs ontogeny is essential to the basic knowledge of RKN-plant interaction and to discover novel and effective control strategies. Hence, we report for the first time in a model plant, Arabidopsis, molecular, and cellular features concerning ectopic de novo organogenesis of RKNs GCs in leaves. RKNs induce GCs in leaves with irregular shape, a reticulated cytosol, and fragmented vacuoles as GCs from roots. Leaf cells around the nematode enter G2-M shown by ProCycB1;1:CycB1;1(NT)-GUS expression, consistent to multinucleated GCs. In addition, GCs nuclei present irregular and varied sizes. All these characteristics mentioned, being equivalent to GCs in root-galls. RKNs complete their life cycle forming a gall/callus-like structure in the leaf vascular tissues resembling auxin-induced callus with an auxin-response maxima, indicated by high expression of DR5::GUS that is dependent on leaf auxin-transport. Notably, induction of leaves calli/GCs requires molecular components from roots crucial for lateral roots (LRs), auxin-induced callus and root-gall formation, i.e., LBD16. Hence, LBD16 is a xylem pole pericycle specific and local marker in LR primordia unexpectedly induced locally in the vascular tissue of leaves after RKN infection. LBD16 is also fundamental for feeding site formation as RKNs could not stablish in 35S::LBD16-SRDX leaves, and likely it is also a conserved molecular hub between biotic and developmental signals in Arabidopsis either in roots or leaves. Moreover, RKNs induce the ectopic development of roots from leaf and root-galls, also formed in mutants compromised in LR formation, arf7/arf19 , slr , and alf4 . Therefore, nematodes must target molecular signatures to induce post-embryogenic de novo organogenesis through the LBD16 callus formation pathway partially different from those prevalent during normal LR development.

Induced Jasmonate Signaling Leads to Contrasting Effects on Root Damage and Herbivore Performance1

PubMed Central

Lu, Jing; Robert, Christelle Aurélie Maud; Riemann, Michael; Cosme, Marco; Mène-Saffrané, Laurent; Massana, Josep; Stout, Michael Joseph; Lou, Yonggen; Gershenzon, Jonathan; Erb, Matthias

2015-01-01

Induced defenses play a key role in plant resistance against leaf feeders. However, very little is known about the signals that are involved in defending plants against root feeders and how they are influenced by abiotic factors. We investigated these aspects for the interaction between rice (Oryza sativa) and two root-feeding insects: the generalist cucumber beetle (Diabrotica balteata) and the more specialized rice water weevil (Lissorhoptrus oryzophilus). Rice plants responded to root attack by increasing the production of jasmonic acid (JA) and abscisic acid, whereas in contrast to in herbivore-attacked leaves, salicylic acid and ethylene levels remained unchanged. The JA response was decoupled from flooding and remained constant over different soil moisture levels. Exogenous application of methyl JA to the roots markedly decreased the performance of both root herbivores, whereas abscisic acid and the ethylene precursor 1-aminocyclopropane-1-carboxylic acid did not have any effect. JA-deficient antisense 13-lipoxygenase (asLOX) and mutant allene oxide cyclase hebiba plants lost more root biomass under attack from both root herbivores. Surprisingly, herbivore weight gain was decreased markedly in asLOX but not hebiba mutant plants, despite the higher root biomass removal. This effect was correlated with a herbivore-induced reduction of sucrose pools in asLOX roots. Taken together, our experiments show that jasmonates are induced signals that protect rice roots from herbivores under varying abiotic conditions and that boosting jasmonate responses can strongly enhance rice resistance against root pests. Furthermore, we show that a rice 13-lipoxygenase regulates root primary metabolites and specifically improves root herbivore growth. PMID:25627217

Aluminium-induced reduction of plant growth in alfalfa (Medicago sativa) is mediated by interrupting auxin transport and accumulation in roots.

PubMed

Wang, Shengyin; Ren, Xiaoyan; Huang, Bingru; Wang, Ge; Zhou, Peng; An, Yuan

2016-07-20

The objective of this study was to investigate Al(3+)-induced IAA transport, distribution, and the relation of these two processes to Al(3+)-inhibition of root growth in alfalfa. Alfalfa seedlings with or without apical buds were exposed to 0 or 100 μM AlCl3 and were foliar sprayed with water or 6 mg L(-1) IAA. Aluminium stress resulted in disordered arrangement of cells, deformed cell shapes, altered cell structure, and a shorter length of the meristematic zone in root tips. Aluminium stress significantly decreased the IAA concentration in apical buds and root tips. The distribution of IAA fluorescence signals in root tips was disturbed, and the IAA transportation from shoot base to root tip was inhibited. The highest intensity of fluorescence signals was detected in the apical meristematic zone. Exogenous application of IAA markedly alleviated the Al(3+)-induced inhibition of root growth by increasing IAA accumulation and recovering the damaged cell structure in root tips. In addition, Al(3+) stress up-regulated expression of AUX1 and PIN2 genes. These results indicate that Al(3+)-induced reduction of root growth could be associated with the inhibitions of IAA synthesis in apical buds and IAA transportation in roots, as well as the imbalance of IAA distribution in root tips.

Aluminium-induced reduction of plant growth in alfalfa (Medicago sativa) is mediated by interrupting auxin transport and accumulation in roots

PubMed Central

Wang, Shengyin; Ren, Xiaoyan; Huang, Bingru; Wang, Ge; Zhou, Peng; An, Yuan

2016-01-01

The objective of this study was to investigate Al3+-induced IAA transport, distribution, and the relation of these two processes to Al3+-inhibition of root growth in alfalfa. Alfalfa seedlings with or without apical buds were exposed to 0 or 100 μM AlCl3 and were foliar sprayed with water or 6 mg L−1 IAA. Aluminium stress resulted in disordered arrangement of cells, deformed cell shapes, altered cell structure, and a shorter length of the meristematic zone in root tips. Aluminium stress significantly decreased the IAA concentration in apical buds and root tips. The distribution of IAA fluorescence signals in root tips was disturbed, and the IAA transportation from shoot base to root tip was inhibited. The highest intensity of fluorescence signals was detected in the apical meristematic zone. Exogenous application of IAA markedly alleviated the Al3+-induced inhibition of root growth by increasing IAA accumulation and recovering the damaged cell structure in root tips. In addition, Al3+ stress up-regulated expression of AUX1 and PIN2 genes. These results indicate that Al3+-induced reduction of root growth could be associated with the inhibitions of IAA synthesis in apical buds and IAA transportation in roots, as well as the imbalance of IAA distribution in root tips. PMID:27435109

Transcription coactivator Arabidopsis ANGUSTIFOLIA3 modulates anthocyanin accumulation and light-induced root elongation through transrepression of Constitutive Photomorphogenic1.

PubMed

Meng, Lai-Sheng

2015-04-01

ANGUSTIFOLIA3 (AN3), a transcription coactivator, is implicated in modulating cell proliferation. In this study, I found that AN3 is a novel regulator of anthocyanin biosynthesis and light-induced root elongation. Seedlings and seeds lacking AN3 activity presented significantly reduced anthocyanin accumulation and light-induced root elongation, whereas those of transgenic plants harbouring the 35S:AN3 construct exhibited increased anthocyanin accumulation. AN3 is required for the proper expression of other genes that affect anthocyanin accumulation and light-induced root elongation, Constitutive Photomorphogenic1 (COP1), encoding a RING motif - containing E3 ubiquitin ligase. AN3 was associated with COP1 promoter in vivo. Thus, AN3 may act with other proteins that bind to COP1 promoter to promote anthocyanin accumulation and inhibit light-induced root elongation. © 2014 John Wiley & Sons Ltd.

Effect of pH and calcium on short-term NO3- fluxes in roots of barley seedlings

NASA Technical Reports Server (NTRS)

Aslam, M.; Travis, R. L.; Huffaker, R. C.

1995-01-01

The effect of pH and Ca2+ on net NO3- uptake, influx, and efflux by intact roots of barley (Hordeum vulgare L.) seedlings was studied. Seedlings were induced with NO3- or NO2-. Net NO3- uptake and efflux, respectively, were determined by following its depletion from, and accumulation in, the external solution. Since roots of both uninduced and NO2(-)-induced seedlings contain little internal NO3- initial net uptake rates are equivalent to influx (M. Aslam, R.L. Travis, R.C. Huffaker [1994] Plant Physiol 106: 1293-1301). NO3-, uptake (influx) by these roots was little affected at acidic pH. In contrast, in NO3(-)-induced roots, which accumulate NO3-, net uptake rates decreased in response to acidic pH. Under these conditions, NO3- efflux was stimulated and was a function of root NO3- concentration. Conversely, at basic pH, NO3- uptake by NO3- and NO2(-)-induced and uninduced roots decreased, apparently because of the inhibition of influx. Calcium had little effect on NO3- uptake (influx) by NO2(-)-induced roots at either pH 3 or 6. However, in NO3(-)-induced roots, lack of Ca2+ at pH 3 significantly decreased net NO3- uptake and stimulated efflux. The results indicate that at acidic pH the decrease in net NO3- uptake is due to the stimulation of efflux, whereas at basic pH, it is due to the inhibition of influx.

Simulating root-induced rhizosphere deformation and its effect on water flow

NASA Astrophysics Data System (ADS)

Aravena, J. E.; Ruiz, S.; Mandava, A.; Regentova, E. E.; Ghezzehei, T.; Berli, M.; Tyler, S. W.

2011-12-01

Soil structure in the rhizosphere is influenced by root activities, such as mucilage production, microbial activity and root growth. Root growth alters soil structure by moving and deforming soil aggregates, affecting water and nutrient flow from the bulk soil to the root surface. In this study, we utilized synchrotron X-ray micro-tomography (XMT) and finite element analysis to quantify the effect of root-induced compaction on water flow through the rhizosphere to the root surface. In a first step, finite element meshes of structured soil around the root were created by processing rhizosphere XMT images. Then, soil deformation by root expansion was simulated using COMSOL Multiphysics° (Version 4.2) considering the soil an elasto-plastic porous material. Finally, fluid flow simulations were carried out on the deformed mesh to quantify the effect of root-induced compaction on water flow to the root surface. We found a 31% increase in water flow from the bulk soil to the root due to a 56% increase in root diameter. Simulations also show that the increase of root-soil contact area was the dominating factor with respect to the calculated increase in water flow. Increase of inter-aggregate contacts in size and number were observed within a couple of root diameters away from the root surface. But their influence on water flow was, in this case, rather limited compared to the immediate soil-root contact.

The microtubule cytoskeleton does not integrate auxin transport and gravitropism in maize roots

NASA Technical Reports Server (NTRS)

Hasenstein, K. H.; Blancaflor, E. B.; Lee, J. S.

1999-01-01

The Cholodny-Went hypothesis of gravitropism suggests that the graviresponse is controlled by the distribution of auxin. However, the mechanism of auxin transport during the graviresponse of roots is still unresolved. To determine whether the microtubule (MT) cytoskeleton is participating in auxin transport, the cytoskeleton was examined and the movement of 3H-IAA measured in intact and excised taxol, oryzalin, and naphthylphthalamic acid (NPA)-treated roots of Zea mays cv. Merit. Taxol and oryzalin did not inhibit the graviresponse of roots but the auxin transport inhibitor NPA greatly inhibited both auxin transport and graviresponse. NPA had no effect on MT organization in vertical roots, but caused MT reorientation in horizontally placed roots. Regardless of treatment, the organization of MTs in intact roots differed from that in root segments. The MT inhibitors, taxol and oryzalin had opposite effects on the MTs, namely, depolymerization (oryzalin) and stabilization and thickening (taxol), but both treatments caused swelling of the roots. The data indicate that the MT cytoskeleton does not directly interfere with auxin transport or auxin-mediated growth responses in maize roots.

Arthroscopic Medial Meniscus Posterior Root Fixation Using a Modified Mason-Allen Stitch.

PubMed

Chung, Kyu Sung; Ha, Jeong Ku; Ra, Ho Jong; Kim, Jin Goo

2016-02-01

A complete radial tear of the meniscus posterior root, which can effectively cause a state of total meniscectomy via loss of hoop tension, requires that the torn root be repaired. Several methods have been used to repair medial meniscus posterior root tears, most of which are based on a simple stitch technique that is known to have stitch-holding strength. We applied a modified version of the Mason-Allen stitch technique, which is recognized as a method for rotator cuff repair surgery because its locking effect overcomes the potential weakness of simple stitches. This article introduces the medial meniscus posterior root tears repair procedure based on a modified Mason-Allen stitch technique in which 2 strands (i.e., 1 simple horizontal and 1 simple vertical stitch) are used.

Blue-light-induced PIN3 polarization for root negative phototropic response in Arabidopsis.

PubMed

Zhang, Kun-Xiao; Xu, Heng-Hao; Yuan, Ting-Ting; Zhang, Liang; Lu, Ying-Tang

2013-10-01

Root negative phototropism is an important response in plants. Although blue light is known to mediate this response, the cellular and molecular mechanisms underlying root negative phototropism remain unclear. Here, we report that the auxin efflux carrier PIN-FORMED (PIN) 3 is involved in asymmetric auxin distribution and root negative phototropism. Unilateral blue-light illumination polarized PIN3 to the outer lateral membrane of columella cells at the illuminated root side, and increased auxin activity at the illuminated side of roots, where auxin promotes growth and causes roots bending away from the light source. Furthermore, root negative phototropic response and blue-light-induced PIN3 polarization were modulated by a brefeldin A-sensitive, GNOM-dependent, trafficking pathway and by phot1-regulated PINOID (PID)/PROTEIN PHOSPHATASE 2A (PP2A) activity. Our results indicate that blue-light-induced PIN3 polarization is needed for asymmetric auxin distribution during root negative phototropic response. © 2013 The Authors The Plant Journal © 2013 John Wiley & Sons Ltd.

Cytochemical localization of calcium in cap cells of primary roots of Zea mays L

NASA Technical Reports Server (NTRS)

Moore, R.

1985-01-01

The cellular distribution of Ca in caps of primary roots of Zea mays was examined during the onset and early stages of gravicurvature to determine its possible role in root gravitropism. Staining becomes associated with the portion of the cell wall adjacent to the distal end of the cell after five minutes, and persists throughout the onset of gravicurvature. The outermost peripheral cells of roots oriented horizontally and vertically secrete Ca through plasmodesmata-like channels in their cell walls. Data suggest that Ca is not transported laterally through the columella tissue,but rather that the movement of Ca to the lower side of caps of horizontally-oriented roots is at least partially through and/or on the mucilage of the cap, and via an electrochemical gradient. An important role in root gravitropism is indicated for Ca secretion by peripheral cells.

Postprocedural problems in an overdenture population: a longitudinal study.

PubMed

Ettinger, Ronald L; Qian, Fang

2004-05-01

This study reports on endodontic and other post-procedural problems experienced by overdenture patients from 1973 to 1996. There were 395 subjects enrolled in the study; 273 fulfilled the recall criteria. At recall, all subjects were examined by a single examiner, and appropriate maintenance care was performed. The 273 subjects had 666 abutments and 626 endodontically treated teeth; of these, 51 subjects had postprocedural problems in 81 teeth. Thus, 87.1% of the endodontically treated teeth had no postprocedural problems, and 12.9% had postprocedural problems. Of the subpopulation with postprocedural problems, the most common problem was endodontically treated teeth developing periradicular lesions (37.0%) because of recurrent caries causing loss of the restoration sealing the root canal. Twenty of the 30 teeth were successfully retreated. The next most common problem was vertical root fractures (30.9%), followed by vital teeth developing periradicular lesions (19.8%). Most of the failures could have been prevented by better oral hygiene. Vertical root fractures were statistically associated with abutments in the maxilla and opposed by natural teeth; protection of these abutments with thimble crowns could prevent fractures.

Mangrove peat analysis and reconstruction of vegetation history at the Pelican Cays, Belize

USGS Publications Warehouse

McKee, K.L.; Faulkner, P.L.

2000-01-01

The substrate beneath mangrove forests in the Pelican Cays complex is predominately peat composed mainly of mangrove roots. Leaves and wood account for less than 20% of the peat mass. At Cat Cay, the depth of the peat ranges from 0.2 m along the shoreline to 1.65 m in the island center, indicating that the island has expanded horizontally as well as vertically through below-ground, biogenic processes. Mangrove roots thus play a critical role in the soil formation, vertical accretion, and stability of these mangrove cays. The species composition of fossil roots changes markedly with depth: Rhizophora mangle (red mangrove) was the initial colonizer on a coral base, followed by Avicennia germinans (black mangrove), which increased in abundance and expanded radially from the center of the island. The center of the Avicennia stand ultimately died, leaving an unvegetated, shallow pond. The peat thus retains a record of mangrove development, succession, and deterioration in response to sea-level change and concomitant hydroedaphic conditions controlling dispersal, establishment, growth, and mortality of mangroves on oceanic islands in Belize.

Jasmonic Acid Enhances Al-Induced Root Growth Inhibition1[OPEN

PubMed Central

Yang, Zhong-Bao; Ma, Yanqi

2017-01-01

Phytohormones such as ethylene and auxin are involved in the regulation of the aluminum (Al)-induced root growth inhibition. Although jasmonate (JA) has been reported to play a crucial role in the regulation of root growth and development in response to environmental stresses through interplay with ethylene and auxin, its role in the regulation of root growth response to Al stress is not yet known. In an attempt to elucidate the role of JA, we found that exogenous application of JA enhanced the Al-induced root growth inhibition. Furthermore, phenotype analysis with mutants defective in either JA biosynthesis or signaling suggests that JA is involved in the regulation of Al-induced root growth inhibition. The expression of the JA receptor CORONATINE INSENSITIVE1 (COI1) and the key JA signaling regulator MYC2 was up-regulated in response to Al stress in the root tips. This process together with COI1-mediated Al-induced root growth inhibition under Al stress was controlled by ethylene but not auxin. Transcriptomic analysis revealed that many responsive genes under Al stress were regulated by JA signaling. The differential responsive of microtubule organization-related genes between the wild-type and coi1-2 mutant is consistent with the changed depolymerization of cortical microtubules in coi1 under Al stress. In addition, ALMT-mediated malate exudation and thus Al exclusion from roots in response to Al stress was also regulated by COI1-mediated JA signaling. Together, this study suggests that root growth inhibition is regulated by COI1-mediated JA signaling independent from auxin signaling and provides novel insights into the phytohormone-mediated root growth inhibition in response to Al stress. PMID:27932419

Jasmonic Acid Enhances Al-Induced Root Growth Inhibition.

PubMed

Yang, Zhong-Bao; He, Chunmei; Ma, Yanqi; Herde, Marco; Ding, Zhaojun

2017-02-01

Phytohormones such as ethylene and auxin are involved in the regulation of the aluminum (Al)-induced root growth inhibition. Although jasmonate (JA) has been reported to play a crucial role in the regulation of root growth and development in response to environmental stresses through interplay with ethylene and auxin, its role in the regulation of root growth response to Al stress is not yet known. In an attempt to elucidate the role of JA, we found that exogenous application of JA enhanced the Al-induced root growth inhibition. Furthermore, phenotype analysis with mutants defective in either JA biosynthesis or signaling suggests that JA is involved in the regulation of Al-induced root growth inhibition. The expression of the JA receptor CORONATINE INSENSITIVE1 (COI1) and the key JA signaling regulator MYC2 was up-regulated in response to Al stress in the root tips. This process together with COI1-mediated Al-induced root growth inhibition under Al stress was controlled by ethylene but not auxin. Transcriptomic analysis revealed that many responsive genes under Al stress were regulated by JA signaling. The differential responsive of microtubule organization-related genes between the wild-type and coi1-2 mutant is consistent with the changed depolymerization of cortical microtubules in coi1 under Al stress. In addition, ALMT-mediated malate exudation and thus Al exclusion from roots in response to Al stress was also regulated by COI1-mediated JA signaling. Together, this study suggests that root growth inhibition is regulated by COI1-mediated JA signaling independent from auxin signaling and provides novel insights into the phytohormone-mediated root growth inhibition in response to Al stress. © 2017 American Society of Plant Biologists. All Rights Reserved.

An ethylene and ROS-dependent pathway is involved in low ammonium-induced root hair elongation in Arabidopsis seedlings.

PubMed

Zhu, Changhua; Yang, Na; Guo, Zhengfei; Qian, Meng; Gan, Lijun

2016-08-01

Root hairs are plastic in response to nutrient supply, but relatively little is known about their development under low ammonium (NH4(+)) conditions. This study showed that reducing NH4(+) for 3 days in wild-type Arabidopsis seedlings resulted in drastic elongation of root hairs. To investigate the possible mediation of ethylene and auxin in this process, seedlings were treated with 2,3,5-triiodobenzoic acid (TIBA, auxin transport inhibitor), 1-naphthylphthalamic acid (NPA, auxin transport inhibitor), p-chlorophenoxy isobutyric acid (PCIB, auxin action inhibitor), aminoethoxyvinylglycine (AVG, chemical inhibitor of ethylene biosynthesis), or silver ions (Ag(+), ethylene perception antagonist) under low NH4(+) conditions. Our results showed that TIBA, NPA and PCIB did not inhibit root hair elongation under low NH4(+) conditions, while AVG and Ag(+) completely inhibited low NH4(+)-induced root hair elongation. This suggested that low NH4(+)-induced root hair elongation was dependent on the ethylene pathway, but not the auxin pathway. Further genetic studies revealed that root hair elongation in auxin-insensitive mutants was sensitive to low NH4(+) treatment, but elongation was less sensitive in ethylene-insensitive mutants than wild-type plants. In addition, low NH4(+)-induced root hair elongation was accompanied by reactive oxygen species (ROS) accumulation. Diphenylene iodonium (DPI, NADPH oxidase inhibitor) and dimethylthiourea (DMTU, ROS scavenger) inhibited low NH4(+)-induced root hair elongation, suggesting that ROS were involved in this process. Moreover, ethylene acted together with ROS to modulate root hair elongation under low NH4(+) conditions. These results demonstrate that a signaling pathway involving ethylene and ROS participates in regulation of root hair elongation when Arabidopsis seedlings are subjected to low NH4(+) conditions. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Leaf Abscission Induced by Ethylene in Water-Stressed Intact Seedlings of Cleopatra Mandarin Requires Previous Abscisic Acid Accumulation in Roots.

PubMed Central

Gomez-Cadenas, A.; Tadeo, F. R.; Talon, M.; Primo-Millo, E.

1996-01-01

The involvement of abscisic acid (ABA) in the process of leaf abscission induced by 1-aminocyclopropane-1-carboxylic acid (ACC) transported from roots to shoots in Cleopatra mandarin (Citrus reshni Hort. ex Tan.) seedlings grown under water stress was studied using norflurazon (NF). Water stress induced both ABA (24-fold) and ACC (16-fold) accumulation in roots and arrested xylem flow. Leaf bulk ABA also increased (8-fold), although leaf abscission did not occur. Shortly after rehydration, root ABA and ACC returned to their prestress levels, whereas sharp and transitory increases of ACC (17-fold) and ethylene (10-fold) in leaves and high percentages of abscission (up to 47%) were observed. NF suppressed the ABA and ACC accumulation induced by water stress in roots and the sharp increases of ACC and ethylene observed after rewatering in leaves. NF also reduced leaf abscission (7-10%). These results indicate that water stress induces root ABA accumulation and that this is required for the process of leaf abscission to occur. It was also shown that exogenous ABA increases ACC levels in roots but not in leaves. Collectively, the data suggest that ABA, the primary sensitive signal to water stress, modulates the levels of ethylene, which is the hormonal activator of leaf abscission. This assumption implies that root ACC levels are correlated with root ABA amounts in a dependent way, which eventually links water status to an adequate, protective response such as leaf abscission. PMID:12226398

Effect of Metal Artifacts on Detection of Vertical Root Fractures Using Two Cone Beam Computed Tomography Systems.

PubMed

Safi, Yaser; Aghdasi, Mohammad Mehdi; Ezoddini-Ardakani, Fatemeh; Beiraghi, Samira; Vasegh, Zahra

2015-01-01

Vertical root fracture (VRF) is common in endodontically treated teeth. Conventional and digital radiographies have limitations for detection of VRFs. Cone-beam computed tomography (CBCT) offers greater detection accuracy of VRFs in comparison with conventional radiography. This study compared the effects of metal artifacts on detection of VRFs by using two CBCT systems. Eighty extracted premolars were selected and sectioned at the level of the cemento enamel junction (CEJ). After preparation, root canals were filled with gutta-percha. Subsequently, two thirds of the root fillings were removed for post space preparation and a custom-made post was cemented into each canal. The teeth were randomly divided into two groups (n=40). In the test group, root fracture was created with Instron universal testing machine. The control teeth remained intact. CBCT scans of all teeth were obtained with either New Tom VGI or Soredex Scanora 3D. Three observers analyzed the images for detection of VRF. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for VRF detection and percentage of probable cases were calculated for each imaging system and compared using non-parametric tests considering the non-normal distribution of data. The inter-observer reproducibility was calculated using the weighted kappa coefficient. There were no statistically significant differences in sensitivity, specificity, PPV and NPV between the two CBCT systems. The effect of metal artifacts on VRF detection was not significantly different between the two CBCT systems.

Comparison of two surgical procedures for use of the acellular dermal matrix graft in the treatment of gingival recessions: a randomized controlled clinical study.

PubMed

Felipe, Maria Emília M C; Andrade, Patrícia F; Grisi, Marcio F M; Souza, Sérgio L S; Taba, Mário; Palioto, Daniela B; Novaes, Arthur B

2007-07-01

The aim of this randomized, controlled, clinical investigation was to compare two surgical techniques for root coverage with the acellular dermal matrix graft to evaluate which technique provided better root coverage, a better esthetic result, and less postoperative discomfort. Fifteen patients with bilateral Miller Class I or II gingival recessions were selected. Fifteen pairs of recessions were treated and assigned randomly to the test group, and the contralateral recessions were assigned to the control group. The control group was treated with a broader flap and vertical releasing incisions; the test group was treated with the proposed surgical technique, without vertical releasing incisions. The clinical parameters evaluated were probing depth, relative clinical attachment level, gingival recession (GR), width of keratinized tissue, thickness of keratinized tissue, esthetic result, and pain evaluation. The measurements were taken before the surgeries and after 6 months. At baseline, all parameters were similar for both groups. At 6 months, a statistically significant greater reduction in GR favored the control group. The percentage of root coverage was 68.98% and 84.81% for the test and control groups, respectively. The esthetic result was equivalent between the groups, and all patients tolerated both procedures well. Both techniques provided significant root coverage, good esthetic results, and similar levels of postoperative discomfort. However, the control technique had statistically significantly better results for root coverage of localized gingival recessions.

Biomechanical studies on the effect of iatrogenic dentin removal on vertical root fractures

PubMed Central

Ossareh, A.; Rosentritt, M.; Kishen, A.

2018-01-01

Introduction: The aim of this study was to understand the mechanism by which iatrogenic root dentin removal influences radicular stress distribution and subsequently affects the resistance to vertical root fractures (VRF) in endodontically treated teeth. Materials and Methods: The experiments were conducted in two phases. Phase 1: freshly extracted premolar teeth maintained in phosphate-buffered saline were instrumented to simulate three different degrees of dentin removal, designated as low, medium, and extreme groups. Micro-Ct analyzes were performed to quantitatively determine: (a) the amount of dentin removed, (b) the remaining dentin volume, and (c) the moment of inertia of root dentin. The specimens were then subjected to thermomechanical cycling and continuous loading to determine (a) the mechanical load to fracture and (b) dentin microcracking (fractography) using scanning electron microscopy. Phase 2: Finite element analysis was used to evaluate the influence of dentin removal on the stress distribution pattern in root dentin. The data obtained were analyzed using one-way ANOVA and Tukey's post hoc test (P < 0.05). Results: Phase 1: A significantly greater volume of dentin was removed from teeth in extreme group when compared to low group (P < 0.01). The mechanical analysis showed that the load to fracture was significantly lower in teeth from extreme group (P < 0.05). A linear relationship was observed between the moment of inertia and load to fracture in all experimental groups (R2 = 0.52). Fractography showed that most microcracks were initiated from the root canal walls in extreme group. Phase 2: The numerical analysis showed that the radicular stress distribution increased apically and buccolingually with greater degree of root canal dentin removal. Conclusions: The combined experimental/numerical analyses highlighted the influence of remaining root dentin volume on the radicular bending resistance, stress distribution pattern, and subsequent propensity to VRF. PMID:29899632

A fungal endophyte helps plants to tolerate root herbivory through changes in gibberellin and jasmonate signaling.

PubMed

Cosme, Marco; Lu, Jing; Erb, Matthias; Stout, Michael Joseph; Franken, Philipp; Wurst, Susanne

2016-08-01

Plant-microbe mutualisms can improve plant defense, but the impact of root endophytes on below-ground herbivore interactions remains unknown. We investigated the effects of the root endophyte Piriformospora indica on interactions between rice (Oryza sativa) plants and its root herbivore rice water weevil (RWW; Lissorhoptrus oryzophilus), and how plant jasmonic acid (JA) and GA regulate this tripartite interaction. Glasshouse experiments with wild-type rice and coi1-18 and Eui1-OX mutants combined with nutrient, jasmonate and gene expression analyses were used to test: whether RWW adult herbivory above ground influences subsequent damage caused by larval herbivory below ground; whether P. indica protects plants against RWW; and whether GA and JA signaling mediate these interactions. The endophyte induced plant tolerance to root herbivory. RWW adults and larvae acted synergistically via JA signaling to reduce root growth, while endophyte-elicited GA biosynthesis suppressed the herbivore-induced JA in roots and recovered plant growth. Our study shows for the first time the impact of a root endophyte on plant defense against below-ground herbivores, adds to growing evidence that induced tolerance may be an important root defense, and implicates GA as a signal component of inducible plant tolerance against biotic stress. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

Trichoderma-Induced Acidification Is an Early Trigger for Changes in Arabidopsis Root Growth and Determines Fungal Phytostimulation

PubMed Central

Pelagio-Flores, Ramón; Esparza-Reynoso, Saraí; Garnica-Vergara, Amira; López-Bucio, José; Herrera-Estrella, Alfredo

2017-01-01

Trichoderma spp. are common rhizosphere inhabitants widely used as biological control agents and their role as plant growth promoting fungi has been established. Although soil pH influences several fungal and plant functional traits such as growth and nutrition, little is known about its influence in rhizospheric or mutualistic interactions. The role of pH in the Trichoderma–Arabidopsis interaction was studied by determining primary root growth and lateral root formation, root meristem status and cell viability, quiescent center (QC) integrity, and auxin inducible gene expression. Primary root growth phenotypes in wild type seedlings and STOP1 mutants allowed identification of a putative root pH sensing pathway likely operating in plant–fungus recognition. Acidification by Trichoderma induced auxin redistribution within Arabidopsis columella root cap cells, causing root tip bending and growth inhibition. Root growth stoppage correlated with decreased cell division and with the loss of QC integrity and cell viability, which were reversed by buffering the medium. In addition, stop1, an Arabidopsis mutant sensitive to low pH, was oversensitive to T. atroviride primary root growth repression, providing genetic evidence that a pH root sensing mechanism reprograms root architecture during the interaction. Our results indicate that root sensing of pH mediates the interaction of Trichoderma with plants. PMID:28567051

Induced jasmonate signaling leads to contrasting effects on root damage and herbivore performance.

PubMed

Lu, Jing; Robert, Christelle Aurélie Maud; Riemann, Michael; Cosme, Marco; Mène-Saffrané, Laurent; Massana, Josep; Stout, Michael Joseph; Lou, Yonggen; Gershenzon, Jonathan; Erb, Matthias

2015-03-01

Induced defenses play a key role in plant resistance against leaf feeders. However, very little is known about the signals that are involved in defending plants against root feeders and how they are influenced by abiotic factors. We investigated these aspects for the interaction between rice (Oryza sativa) and two root-feeding insects: the generalist cucumber beetle (Diabrotica balteata) and the more specialized rice water weevil (Lissorhoptrus oryzophilus). Rice plants responded to root attack by increasing the production of jasmonic acid (JA) and abscisic acid, whereas in contrast to in herbivore-attacked leaves, salicylic acid and ethylene levels remained unchanged. The JA response was decoupled from flooding and remained constant over different soil moisture levels. Exogenous application of methyl JA to the roots markedly decreased the performance of both root herbivores, whereas abscisic acid and the ethylene precursor 1-aminocyclopropane-1-carboxylic acid did not have any effect. JA-deficient antisense 13-lipoxygenase (asLOX) and mutant allene oxide cyclase hebiba plants lost more root biomass under attack from both root herbivores. Surprisingly, herbivore weight gain was decreased markedly in asLOX but not hebiba mutant plants, despite the higher root biomass removal. This effect was correlated with a herbivore-induced reduction of sucrose pools in asLOX roots. Taken together, our experiments show that jasmonates are induced signals that protect rice roots from herbivores under varying abiotic conditions and that boosting jasmonate responses can strongly enhance rice resistance against root pests. Furthermore, we show that a rice 13-lipoxygenase regulates root primary metabolites and specifically improves root herbivore growth. © 2015 American Society of Plant Biologists. All Rights Reserved.

Ethylene Promotes Cadmium-induced Root Growth Inhibition through EIN3 controlled XTH33 and LSU1 expression in Arabidopsis.

PubMed

Kong, Xiangpei; Li, Cuiling; Zhang, Feng; Yu, Qianqian; Gao, Shan; Zhang, Maolin; Tian, Huiyu; Zhang, Jian; Yuan, Xianzheng; Ding, Zhaojun

2018-06-05

Cadmium (Cd) stress is one of the most serious heavy metal stresses limiting plant growth and development. However, the molecular mechanisms underlying Cd-induced root growth inhibition remain unclear. Here, we found that ethylene signaling positively regulates Cd-induced root growth inhibition. Arabidopsis seedlings pretreated with the ethylene precursor 1-aminocyclopropane-1-carboxylic acid exhibited enhanced Cd-induced root growth inhibition; while the addition of the ethylene biosynthesis inhibitor aminoethoxyvinyl glycine decreased Cd-induced root growth inhibition. Consistently, ethylene-insensitive mutants such as ein4-1, ein3-1 eil1-1 double mutant, and EBF1ox, displayed an increased tolerance to Cd. Furthermore, we also observed that Cd inhibited EIN3 protein degradation, a process which was regulated by ethylene signaling. Genetic and biochemical analyses showed that EIN3 enhanced root growth inhibition under Cd stress through direct binding to the promoters and regulating the expression of XTH33 and LSU1, which encode key regulators of cell wall extension and S metabolic process, respectively. Collectively, our study demonstrates that ethylene plays a positive role in Cd-regulated root growth inhibition through EIN3-mediated transcriptional regulation of XTH33 and LSU1, and provides a molecular framework for the integration of environmental signals and intrinsic regulators in modulating plant root growth. This article is protected by copyright. All rights reserved.

Polyamines Interact with Hydroxyl Radicals in Activating Ca2+ and K+ Transport across the Root Epidermal Plasma Membranes1[W

PubMed Central

Zepeda-Jazo, Isaac; Velarde-Buendía, Ana María; Enríquez-Figueroa, René; Bose, Jayakumar; Shabala, Sergey; Muñiz-Murguía, Jesús; Pottosin, Igor I.

2011-01-01

Reactive oxygen species (ROS) are integral components of the plant adaptive responses to environment. Importantly, ROS affect the intracellular Ca2+ dynamics by activating a range of nonselective Ca2+-permeable channels in plasma membrane (PM). Using patch-clamp and noninvasive microelectrode ion flux measuring techniques, we have characterized ionic currents and net K+ and Ca2+ fluxes induced by hydroxyl radicals (OH•) in pea (Pisum sativum) roots. OH•, but not hydrogen peroxide, activated a rapid Ca2+ efflux and a more slowly developing net Ca2+ influx concurrent with a net K+ efflux. In isolated protoplasts, OH• evoked a nonselective current, with a time course and a steady-state magnitude similar to those for a K+ efflux in intact roots. This current displayed a low ionic selectivity and was permeable to Ca2+. Active OH•-induced Ca2+ efflux in roots was suppressed by the PM Ca2+ pump inhibitors eosine yellow and erythrosine B. The cation channel blockers gadolinium, nifedipine, and verapamil and the anionic channel blockers 5-nitro-2(3-phenylpropylamino)-benzoate and niflumate inhibited OH•-induced ionic currents in root protoplasts and K+ efflux and Ca2+ influx in roots. Contrary to expectations, polyamines (PAs) did not inhibit the OH•-induced cation fluxes. The net OH•-induced Ca2+ efflux was largely prolonged in the presence of spermine, and all PAs tested (spermine, spermidine, and putrescine) accelerated and augmented the OH•-induced net K+ efflux from roots. The latter effect was also observed in patch-clamp experiments on root protoplasts. We conclude that PAs interact with ROS to alter intracellular Ca2+ homeostasis by modulating both Ca2+ influx and efflux transport systems at the root cell PM. PMID:21980172

Nitric oxide enhances development of lateral roots in tomato (Solanum lycopersicum L.) under elevated carbon dioxide.

PubMed

Wang, Huan; Xiao, Wendan; Niu, Yaofang; Jin, Chongwei; Chai, Rushan; Tang, Caixian; Zhang, Yongsong

2013-01-01

Elevated carbon dioxide (CO₂) has been shown to enhance the growth and development of plants, especially of roots. Amongst them, lateral roots play an important role in nutrient uptake, and thus alleviate the nutrient limitation to plant growth under elevated CO₂. This paper examined the mechanism underlying CO₂ elevation-induced lateral root formation in tomato. The endogenous nitric oxide (NO) in roots was detected by the specific probe 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate (DAF-FM DA). We suggest that CO₂ elevation-induced NO accumulation was important for lateral root formation. Elevated CO₂ significantly increased the activity of nitric oxide synthase in roots, but not nitrate reductase activity. Moreover, the pharmacological evidence showed that nitric oxide synthase rather than nitrate reductase was responsible for CO₂ elevation-induced NO accumulation. Elevated CO₂ enhanced the activity of nitric oxide synthase and promoted production of NO, which was involved in lateral root formation in tomato under elevated CO₂.

Apical closure of mature molar roots with the use of calcium hydroxide.

PubMed

Rotstein, I; Friedman, S; Katz, J

1990-11-01

Calcium hydroxide may induce apical root closure in affected mature teeth as well as in immature teeth. Once an apical hard tissue barrier is formed, a permanent root canal filling can be safely condensed. Two cases are described in which calcium hydroxide induced apical root closure in mature molar teeth where the apical constriction was lost because of chronic inflammatory process.

A Unified Geodetic Vertical Velocity Field (UGVVF), Version 1.0

NASA Astrophysics Data System (ADS)

Schmalzle, G.; Wdowinski, S.

2014-12-01

Tectonic motion, volcanic inflation or deflation, as well as oil, gas and water pumping can induce vertical motion. In southern California these signals are inter-mingled. In tectonics, properly identifying regions that are contaminated by other signals can be important when estimating fault slip rates. Until recently vertical deformation rates determined by high precision Global Positioning Systems (GPS) had large uncertainties compared to horizontal components and were rarely used to constrain tectonic models of fault motion. However, many continuously occupied GPS stations have been operating for ten or more years, often delivering uncertainties of ~1 mm/yr or less, providing better constraints for tectonic modeling. Various processing centers produced GPS time series and estimated vertical velocity fields, each with their own set of processing techniques and assumptions. We compare vertical velocity solutions estimated by seven data processing groups as well as two combined solutions (Figure 1). These groups include: Central Washington University (CWU) and New Mexico Institute of Technology (NMT), and their combined solution provided by the Plate Boundary Observatory (PBO) through the UNAVCO website. Also compared are the Jet Propulsion Laboratory (JPL) and Scripps Orbit and Permanent Array Center (SOPAC) and their combined solution provided as part of the NASA MEaSUREs project. Smaller velocity fields included are from Amos et al., 2014, processed at the Nevada Geodetic Laboratory, Shen et al., 2011, processed by UCLA and called the Crustal Motion Map 4.0 (CMM4) dataset, and a new velocity field provided by the University of Miami (UM). Our analysis includes estimating and correcting for systematic vertical velocity and uncertainty differences between groups. Our final product is a unified velocity field that contains the median values of the adjusted velocity fields and their uncertainties. This product will be periodically updated when new velocity fields become available. A database and scripts to access the database will be available through the University of Miami (http://www.geodesy.miami.edu) website. Figure 1. Vertical velocity comparisons between processing groups (blue dots). Red line indicates equal velocities. Weighted Root Mean Square (WRMS) is shown.

Ulinastatin attenuates neuropathic pain induced by L5-VRT via the calcineurin/IL-10 pathway.

PubMed

Ouyang, Handong; Nie, Bilin; Wang, Peizong; Li, Qiang; Huang, Wan; Xin, Wenjun; Zeng, Weian; Liu, Xianguo

2016-01-01

Previous studies have shown that ulinastatin, an effective inhibitor of the inflammatory response in clinical applications, can attenuate hyperalgesia in rodents. However, the underlying mechanism remains unclear. In the present study, we first examined the change in the calcineurin level, which plays an important role in regulating cytokine release in the nervous system, following lumbar 5 ventral root transection in the rat. Furthermore, we determined whether intraperitoneal (i.p.) injection of ulinastatin attenuated pain behavior via inhibition of the calcineurin-mediated inflammatory response induced by lumbar 5 ventral root transection. The results showed that the paw withdrawal threshold and paw withdrawal latency were significantly decreased following lumbar 5 ventral root transection compared to the sham group. Neuropathic pain induced by lumbar 5 ventral root transection significantly decreased the expression of calcineurin in the DRG, and calcineurin was mostly located with NF-200-positive cells, IB4-positive cells, and CGRP-positive cells and less with GFAP-positive satellite cells. Furthermore, intrathecal (i.t.) injection of exogenous calcineurin attenuated the pain behavior induced by lumbar 5 ventral root transection. Importantly, intraperitoneal injection of ulinastatin alleviated the pain behavior and calcineurin downregulation induced by lumbar 5 ventral root transection. Lastly, the cytokine IL-10 was significantly decreased following lumbar 5 ventral root transection, and application of calcineurin (intrathecal) or ulinastatin (intraperitoneal) inhibited the IL-10 downregulation induced by lumbar 5 ventral root transection. These results suggested that ulinastatin, by acting on the CN/IL-10 pathway, might be a novel and effective drug for the treatment of neuropathic pain. © The Author(s) 2016.

Ulinastatin attenuates neuropathic pain induced by L5-VRT via the calcineurin/IL-10 pathway

PubMed Central

Ouyang, Handong; Nie, Bilin; Wang, Peizong; Li, Qiang; Huang, Wan; Xin, Wenjun; Liu, Xianguo

2016-01-01

Previous studies have shown that ulinastatin, an effective inhibitor of the inflammatory response in clinical applications, can attenuate hyperalgesia in rodents. However, the underlying mechanism remains unclear. In the present study, we first examined the change in the calcineurin level, which plays an important role in regulating cytokine release in the nervous system, following lumbar 5 ventral root transection in the rat. Furthermore, we determined whether intraperitoneal (i.p.) injection of ulinastatin attenuated pain behavior via inhibition of the calcineurin-mediated inflammatory response induced by lumbar 5 ventral root transection. The results showed that the paw withdrawal threshold and paw withdrawal latency were significantly decreased following lumbar 5 ventral root transection compared to the sham group. Neuropathic pain induced by lumbar 5 ventral root transection significantly decreased the expression of calcineurin in the DRG, and calcineurin was mostly located with NF-200-positive cells, IB4-positive cells, and CGRP-positive cells and less with GFAP-positive satellite cells. Furthermore, intrathecal (i.t.) injection of exogenous calcineurin attenuated the pain behavior induced by lumbar 5 ventral root transection. Importantly, intraperitoneal injection of ulinastatin alleviated the pain behavior and calcineurin downregulation induced by lumbar 5 ventral root transection. Lastly, the cytokine IL-10 was significantly decreased following lumbar 5 ventral root transection, and application of calcineurin (intrathecal) or ulinastatin (intraperitoneal) inhibited the IL-10 downregulation induced by lumbar 5 ventral root transection. These results suggested that ulinastatin, by acting on the CN/IL-10 pathway, might be a novel and effective drug for the treatment of neuropathic pain. PMID:27175013

A successful treatment of vertical root fracture: a case report and 4-year follow-up.

PubMed

Oztürk, Mine; Unal, Gül Celik

2008-10-01

This case report describes a successful treatment of vertically fractured tooth which was reconstructed with a self-etching dual-cured adhesive resin cement and intentionally replanted without using rotation in conjunction with a bio-absorbable barrier membrane. At a follow-up consultation 4 years later, the tooth was asymptomatic, and attachment gain and bone regeneration were observed. In addition, no ankylosis was detected clinically or radiographically.

Light-regulated gravitropism in seedling roots of maize

NASA Technical Reports Server (NTRS)

Feldman, L. J.; Briggs, W. R.

1987-01-01

Red light-induced changes in the gravitropism of roots of Zea mays variety Merit is a very low fluence response with a threshold of 10(-9) moles per square meter and is not reversible by far red light. Blue light also affects root gravitropism but the sensitivity of roots to blue is 50 to 100 times less than to an equal fluence of red. In Z. mays Merit we conclude that phytochrome is the sole pigment associated with light-induced changes in root gravitropism.

Mandibular first premolar with four canals.

PubMed

Du, Yi; Lee, Angeline H C; Zhang, Chengfei

2013-02-01

A case of endodontic treatment of a mandibular first premolar exhibiting a total of four distinct root canals and four apical foramina is described. This occurrence in mandibular first premolar has rarely been reported in the endodontic literature. Endodontic treatment that considers the anatomic variation of root canal morphology is important to ensure a favorable healing outcome, and its identification could be enhanced by careful examination using a dental operating microscope. Obturation of root canals using a warm vertical compaction technique with a highly-radiopaque root canal sealer, such as AH Plus, after careful ultrasonic activated irrigation with ethylenediaminetetraacetic acid might allow the flow of sealer into the narrowed but unprepared part of the canal. This offers valuable adjuncts for the successful negotiation of calcified main canals, thereby facilitating optimum chemo-mechanical debridement of the root canal system. © 2013 Blackwell Publishing Asia Pty Ltd.

Quantitation of Cellular Dynamics in Growing Arabidopsis Roots with Light Sheet Microscopy

PubMed Central

Birnbaum, Kenneth D.; Leibler, Stanislas

2011-01-01

To understand dynamic developmental processes, living tissues have to be imaged frequently and for extended periods of time. Root development is extensively studied at cellular resolution to understand basic mechanisms underlying pattern formation and maintenance in plants. Unfortunately, ensuring continuous specimen access, while preserving physiological conditions and preventing photo-damage, poses major barriers to measurements of cellular dynamics in growing organs such as plant roots. We present a system that integrates optical sectioning through light sheet fluorescence microscopy with hydroponic culture that enables us to image, at cellular resolution, a vertically growing Arabidopsis root every few minutes and for several consecutive days. We describe novel automated routines to track the root tip as it grows, to track cellular nuclei and to identify cell divisions. We demonstrate the system's capabilities by collecting data on divisions and nuclear dynamics. PMID:21731697

The promoting effects of alginate oligosaccharides on root development in Oryza sativa L. mediated by auxin signaling.

PubMed

Zhang, Yunhong; Yin, Heng; Zhao, Xiaoming; Wang, Wenxia; Du, Yuguang; He, Ailing; Sun, Kegang

2014-11-26

Alginate oligosaccharides (AOS), which are marine oligosaccharides, are involved in regulating plant root growth, but the promotion mechanism for AOS remains unclear. Here, AOS (10-80 mg/L) induced the expression of auxin-related gene (OsYUCCA1, OsYUCCA5, OsIAA11 and OsPIN1) in rice (Oryza sativa L.) tissues to accelerate auxin biosynthesis and transport, and reduced indole-3-acetic acid (IAA) oxidase activity in rice roots. These changes resulted in the increase of 37.8% in IAA concentration in rice roots, thereby inducing the expression of root development-related genes, promoting root growth in a dose-dependent manner, which were inhibited by auxin transport inhibitor 2,3,5-triiodo benzoic acid (TIBA) and calcium-chelating agent ethylene glycol bis (2-aminoethyl) tetraacetic acid (EGTA). AOS also induced calcium signaling generation in rice roots. Those results indicated that auxin mediated AOS regulation of root development, and calcium signaling may act mainly in the upstream of auxin in the regulation of AOS on rice root development. Copyright © 2014 Elsevier Ltd. All rights reserved.

Integration of orientation, clinorotation, and sensitivity in the graviresponse

NASA Astrophysics Data System (ADS)

Hasenstein, Karl H.; John, Susan

Gravitropism describes the response of plants to some acceleration and typically involves amy-loplast displacement. Despite numerous studies, opinions diverge on the perception threshold and persistence of the stimulus. Short-term reorientation in the gravity field and superim-posed mechanostimulation (clinorotation) has the potential to reveal the duration (half-life) of mechanostimulation or memory persistence. Although clinorotation is commonly used to compensate the effect of continuous gravity stimulation, it adds long-term mechanostimulation to short-term reorientation. The constantly changing gravity vector is likely to interfere with curvature and root development. Especially sensitive are columella cells and entire layers have been shown to undergo programmed cell death upon clinorotation. It is unknown to what extent this response depends on the onset, speed, or duration of clinorotation. To determine the susceptibility of the graviresponse on clinorotation, we studied the effects of the rate (0.5 to 5 rpm) of rotation of reoriented flax roots (placed horizontally for 5, 10, or 15 min). Seedlings were kept in the dark, clinorotated either parallel or perpendicular to the root axis and imaged after each rotation by an infrared video camera. Horizontal clinorotation did not affect root growth rate (0.78±0.05 mm/h) but vertical clinorotation reduced root growth by more than 10%. The rate of clinorotation did not affect growth for either condition. However, maximal curvature for vertical clinorotation decreased with increasing rate of rotation and produced straight roots at 5 rpm. Horizontal clinorotation increased curvature with increasing reorienta-tion time and resulted in curvature that increased with the rotation rate. Thus, clinorotation changes the graviresponse but introduces secondary effects that depend on rate and direction of rotation.

Isoliquiritigenin, a strong nod gene- and glyceollin resistance-inducing flavonoid from soybean root exudate.

PubMed

Kape, R; Parniske, M; Brandt, S; Werner, D

1992-05-01

Isoflavonoid signal molecules from soybean (Glycine max (L.) Merr.) seed and root exudate induce the transcription of nodulation (nod) genes in Bradyrhizobium japonicum. In this study, a new compound with symbiotic activity was isolated from soybean root exudate. The isolated 2',4',4-trihydroxychalcone (isoliquiritigenin) is characterized by its strong inducing activity for the nod genes of B. japonicum. These genes are already induced at concentrations 1 order of magnitude below those required of the previously described isoflavonoid inducers genistein and daidzein. Isoliquiritigenin is also a potent inducer of glyceollin resistance in B. japonicum, which renders this bacterium insensitive to potentially bactericidal concentrations of glyceollin, the phytoalexin of G. max. No chemotactic effect of isoliquiritigenin was observed. The highly efficient induction of nod genes and glyceollin resistance by isoliquiritigenin suggests the ecological significance of this compound, although it is not a major flavonoid constituent of the soybean root exudate in quantitative terms.

Nitric Oxide Inhibits Al-Induced Programmed Cell Death in Root Tips of Peanut (Arachis hypogaea L.) by Affecting Physiological Properties of Antioxidants Systems and Cell Wall

PubMed Central

Pan, Chun-Liu; Yao, Shao-Chang; Xiong, Wei-Jiao; Luo, Shu-Zhen; Wang, Ya-Lun; Wang, Ai-Qin; Xiao, Dong; Zhan, Jie; He, Long-Fei

2017-01-01

It has been reported that nitric oxide (NO) is a negative regulator of aluminum (Al)-induced programmed cell death (PCD) in peanut root tips. However, the inhibiting mechanism of NO on Al-induced PCD is unclear. In order to investigate the mechanism by which NO inhibits Al-induced PCD, the effects of co-treatment Al with the exogenous NO donor or the NO-specific scavenger on peanut root tips, the physiological properties of antioxidants systems and cell wall (CW) in root tip cells of NO inhibiting Al-induced PCD were studied with two peanut cultivars. The results showed that Al exposure induced endogenous NO accumulation, and endogenous NO burst increased antioxidant enzyme activity in response to Al stress. The addition of NO donor sodium nitroprusside (SNP) relieved Al-induced root elongation inhibition, cell death and Al adsorption in CW, as well as oxidative damage and ROS accumulation. Furthermore, co-treatment with the exogenous NO donor decreased MDA content, LOX activity and pectin methylesterase (PME) activity, increased xyloglucan endotransglucosylase (XET) activity and relative expression of the xyloglucan endotransglucosylase/hydrolase (XTH-32) gene. Taken together, exogenous NO alleviated Al-induced PCD by inhibiting Al adsorption in CW, enhancing antioxidant defense and reducing peroxidation of membrane lipids, alleviating the inhibition of Al on root elongation by maintaining the extensibility of CW, decreasing PME activity, and increasing XET activity and relative XTH-32 expression of CW. PMID:29311970

Nitric Oxide Inhibits Al-Induced Programmed Cell Death in Root Tips of Peanut (Arachis hypogaea L.) by Affecting Physiological Properties of Antioxidants Systems and Cell Wall.

PubMed

Pan, Chun-Liu; Yao, Shao-Chang; Xiong, Wei-Jiao; Luo, Shu-Zhen; Wang, Ya-Lun; Wang, Ai-Qin; Xiao, Dong; Zhan, Jie; He, Long-Fei

2017-01-01

It has been reported that nitric oxide (NO) is a negative regulator of aluminum (Al)-induced programmed cell death (PCD) in peanut root tips. However, the inhibiting mechanism of NO on Al-induced PCD is unclear. In order to investigate the mechanism by which NO inhibits Al-induced PCD, the effects of co-treatment Al with the exogenous NO donor or the NO-specific scavenger on peanut root tips, the physiological properties of antioxidants systems and cell wall (CW) in root tip cells of NO inhibiting Al-induced PCD were studied with two peanut cultivars. The results showed that Al exposure induced endogenous NO accumulation, and endogenous NO burst increased antioxidant enzyme activity in response to Al stress. The addition of NO donor sodium nitroprusside (SNP) relieved Al-induced root elongation inhibition, cell death and Al adsorption in CW, as well as oxidative damage and ROS accumulation. Furthermore, co-treatment with the exogenous NO donor decreased MDA content, LOX activity and pectin methylesterase (PME) activity, increased xyloglucan endotransglucosylase (XET) activity and relative expression of the xyloglucan endotransglucosylase/hydrolase ( XTH-32 ) gene. Taken together, exogenous NO alleviated Al-induced PCD by inhibiting Al adsorption in CW, enhancing antioxidant defense and reducing peroxidation of membrane lipids, alleviating the inhibition of Al on root elongation by maintaining the extensibility of CW, decreasing PME activity, and increasing XET activity and relative XTH-32 expression of CW.

Mitogen-activated protein kinase signal transduction and DNA repair network are involved in aluminum-induced DNA damage and adaptive response in root cells of Allium cepa L.

PubMed Central

Panda, Brahma B.; Achary, V. Mohan M.

2014-01-01

In the current study, we studied the role of signal transduction in aluminum (Al3+)-induced DNA damage and adaptive response in root cells of Allium cepa L. The root cells in planta were treated with Al3+ (800 μM) for 3 h without or with 2 h pre-treatment of inhibitors of mitogen-activated protein kinase (MAPK), and protein phosphatase. Also, root cells in planta were conditioned with Al3+ (10 μM) for 2 h and then subjected to genotoxic challenge of ethyl methane sulfonate (EMS; 5 mM) for 3 h without or with the pre-treatment of the aforementioned inhibitors as well as the inhibitors of translation, transcription, DNA replication and repair. At the end of treatments, roots cells were assayed for cell death and/or DNA damage. The results revealed that Al3+ (800 μM)-induced significant DNA damage and cell death. On the other hand, conditioning with low dose of Al3+ induced adaptive response conferring protection of root cells from genotoxic stress caused by EMS-challenge. Pre-treatment of roots cells with the chosen inhibitors prior to Al3+-conditioning prevented or reduced the adaptive response to EMS genotoxicity. The results of this study suggested the involvement of MAPK and DNA repair network underlying Al-induced DNA damage and adaptive response to genotoxic stress in root cells of A. cepa. PMID:24926302

Phytochromes A and B mediate red-light-induced positive phototropism in roots

NASA Technical Reports Server (NTRS)

Kiss, John Z.; Mullen, Jack L.; Correll, Melanie J.; Hangarter, Roger P.

2003-01-01

The interaction of tropisms is important in determining the final growth form of the plant body. In roots, gravitropism is the predominant tropistic response, but phototropism also plays a role in the oriented growth of roots in flowering plants. In blue or white light, roots exhibit negative phototropism that is mediated by the phototropin family of photoreceptors. In contrast, red light induces a positive phototropism in Arabidopsis roots. Because this red-light-induced response is weak relative to both gravitropism and negative phototropism, we used a novel device to study phototropism without the complications of a counteracting gravitational stimulus. This device is based on a computer-controlled system using real-time image analysis of root growth and a feedback-regulated rotatable stage. Our data show that this system is useful to study root phototropism in response to red light, because in wild-type roots, the maximal curvature detected with this apparatus is 30 degrees to 40 degrees, compared with 5 degrees to 10 degrees without the feedback system. In positive root phototropism, sensing of red light occurs in the root itself and is not dependent on shoot-derived signals resulting from light perception. Phytochrome (Phy)A and phyB were severely impaired in red-light-induced phototropism, whereas the phyD and phyE mutants were normal in this response. Thus, PHYA and PHYB play a key role in mediating red-light-dependent positive phototropism in roots. Although phytochrome has been shown to mediate phototropism in some lower plant groups, this is one of the few reports indicating a phytochrome-dependent phototropism in flowering plants.

Phytochromes A and B mediate red-light-induced positive phototropism in roots.

PubMed

Kiss, John Z; Mullen, Jack L; Correll, Melanie J; Hangarter, Roger P

2003-03-01

The interaction of tropisms is important in determining the final growth form of the plant body. In roots, gravitropism is the predominant tropistic response, but phototropism also plays a role in the oriented growth of roots in flowering plants. In blue or white light, roots exhibit negative phototropism that is mediated by the phototropin family of photoreceptors. In contrast, red light induces a positive phototropism in Arabidopsis roots. Because this red-light-induced response is weak relative to both gravitropism and negative phototropism, we used a novel device to study phototropism without the complications of a counteracting gravitational stimulus. This device is based on a computer-controlled system using real-time image analysis of root growth and a feedback-regulated rotatable stage. Our data show that this system is useful to study root phototropism in response to red light, because in wild-type roots, the maximal curvature detected with this apparatus is 30 degrees to 40 degrees, compared with 5 degrees to 10 degrees without the feedback system. In positive root phototropism, sensing of red light occurs in the root itself and is not dependent on shoot-derived signals resulting from light perception. Phytochrome (Phy)A and phyB were severely impaired in red-light-induced phototropism, whereas the phyD and phyE mutants were normal in this response. Thus, PHYA and PHYB play a key role in mediating red-light-dependent positive phototropism in roots. Although phytochrome has been shown to mediate phototropism in some lower plant groups, this is one of the few reports indicating a phytochrome-dependent phototropism in flowering plants.

Intensity of hydrostimulation for the induction of root hydrotropism and its sensing by the root cap

NASA Technical Reports Server (NTRS)

Takahashi, H.; Scott, T. K.

1993-01-01

Roots of Pisum sativum L. and Zea mays L. were exposed to different moisture gradients established by placing both wet cheesecloth (hydrostimulant) and saturated aqueous solutions of various salts in a closed chamber. Atmospheric conditions with different relative humidity (RH) in a range between 98 and 86% RH were obtained at root level, 2 to 3mm from the water-saturated hydrostimulant. Roots of Silver Queen corn placed vertically with the tips down curved sideways toward the hydrostimulant in response to approximately 94% RH but did not respond positively to RH higher than approximately 95%. The positive hydrotropic response increased linearly as RH was lowered from 95 to 90%. A maximum response was observed at RH between 90 and 86%. However, RH required for the induction of hydrotropism as well as the responsiveness differed among plant species used; gravitropically sensitive roots appeared to require a somewhat greater moisture gradient for the induction of hydrotropism. Decapped roots of corn failed to curve hydrotropically, suggesting the root cap as a major site of hydrosensing.

High-speed passenger rail tie-ballast interaction.

DOT National Transportation Integrated Search

2015-05-01

This Research Results Report presents : evidence of poor tie support and increased : applied loads that were used to determine the : root cause of transient and permanent vertical : displacements at two Amtrak bridge transitions. : These result...

Inferring field-scale properties of a fractured aquifer from ground surface deformation during a well test

NASA Astrophysics Data System (ADS)

Schuite, Jonathan; Longuevergne, Laurent; Bour, Olivier; Boudin, Frédérick; Durand, Stéphane; Lavenant, Nicolas

2015-12-01

Fractured aquifers which bear valuable water resources are often difficult to characterize with classical hydrogeological tools due to their intrinsic heterogeneities. Here we implement ground surface deformation tools (tiltmetry and optical leveling) to monitor groundwater pressure changes induced by a classical hydraulic test at the Ploemeur observatory. By jointly analyzing complementary time constraining data (tilt) and spatially constraining data (vertical displacement), our results strongly suggest that the use of these surface deformation observations allows for estimating storativity and structural properties (dip, root depth, and lateral extension) of a large hydraulically active fracture, in good agreement with previous studies. Hence, we demonstrate that ground surface deformation is a useful addition to traditional hydrogeological techniques and opens possibilities for characterizing important large-scale properties of fractured aquifers with short-term well tests as a controlled forcing.

Advanced composite vertical stabilizer for DC-10 transport aircraft

NASA Technical Reports Server (NTRS)

Stephens, C. O.

1978-01-01

The structural design configuration for the Composite Vertical Stabilizer is described and the structural design, analysis, and weight activities are presented. The status of fabrication and test activities for the development test portion of the program is described. Test results are presented for the skin panels, spar web, spar cap to cover, and laminate properties specimens. Engineering drawings of vertification test panels and root fittings, rudder support specimens, titanium fittings, and rear spar specimen analysis models are included.

Polyamine-Induced Rapid Root Abscission in Azolla pinnata

PubMed Central

Gurung, Sushma; Cohen, Michael F.; Fukuto, Jon; Yamasaki, Hideo

2012-01-01

Floating ferns of the genus Azolla detach their roots under stress conditions, a unique adaptive response termed rapid root abscission. We found that Azolla pinnata plants exhibited dose-dependent rapid root abscission in response to the polyamines spermidine and spermine after a substantial time lag (>20 min). The duration of the time lag decreased in response to high pH and high temperature whereas high light intensity increased the time lag and markedly lowered the rate of abscission. The oxidation products of polyamines, 1,3-diaminopropane, β-alanine and hydrogen peroxide all failed to initiate root abscission, and hydroxyethyl hydrazine, an inhibitor of polyamine oxidase, did not inhibit spermine-induced root abscission. Exposure of A. pinnata to the polyamines did not result in detectable release of NO and did not affect nitrite-dependent NO production. The finding of polyamine-induced rapid root abscission provides a facile assay for further study of the mode of action of polyamines in plant stress responses. PMID:22997568

Polyamine-Induced Rapid Root Abscission in Azolla pinnata.

PubMed

Gurung, Sushma; Cohen, Michael F; Fukuto, Jon; Yamasaki, Hideo

2012-01-01

Floating ferns of the genus Azolla detach their roots under stress conditions, a unique adaptive response termed rapid root abscission. We found that Azolla pinnata plants exhibited dose-dependent rapid root abscission in response to the polyamines spermidine and spermine after a substantial time lag (>20 min). The duration of the time lag decreased in response to high pH and high temperature whereas high light intensity increased the time lag and markedly lowered the rate of abscission. The oxidation products of polyamines, 1,3-diaminopropane, β-alanine and hydrogen peroxide all failed to initiate root abscission, and hydroxyethyl hydrazine, an inhibitor of polyamine oxidase, did not inhibit spermine-induced root abscission. Exposure of A. pinnata to the polyamines did not result in detectable release of NO and did not affect nitrite-dependent NO production. The finding of polyamine-induced rapid root abscission provides a facile assay for further study of the mode of action of polyamines in plant stress responses.

Light-Regulated Gravitropism in Seedling Roots of Maize 1

PubMed Central

Feldman, Lewis J.; Briggs, Winslow R.

1987-01-01

Red light-induced changes in the gravitropism of roots of Zea mays variety Merit is a very low fluence response with a threshold of 10−9 moles per square meter and is not reversible by far red light. Blue light also affects root gravitropism but the sensitivity of roots to blue is 50 to 100 times less than to an equal fluence of red. In Z. mays Merit we conclude that phytochrome is the sole pigment associated with light-induced changes in root gravitropism. PMID:11539030

Physical properties of root cementum: part 24. Root resorption of the first premolars after 4 weeks of occlusal trauma.

PubMed

Cakmak, Fethiye; Turk, Tamer; Karadeniz, Ersan Ilsay; Elekdag-Turk, Selma; Darendeliler, M Ali

2014-05-01

In orthodontics, adding restorative materials on occlusal or lingual surfaces is a common method to create a mini-biteplane to increase patients' vertical dimension temporarily to facilitate several treatment procedures. However, this method transmits excessive occlusal forces through the periodontal ligament and causes trauma. In this prospective randomized clinical trial, we measured and compared quantitatively the volumes of root resorption after 4 weeks of occlusal trauma. Forty-eight maxillary and mandibular first premolars of 12 patients (6 girls, 6 boys) comprised the sample for this study. One side of each patient was randomly selected as the control. On the contralateral side, a light-cured glass ionomer cement (Transbond Plus Light Cure Band Adhesive; 3M Unitek, Monrovia, Calif) was bonded onto the occlusal surface of the mandibular first premolar so that the cement was in contact with the maxillary first premolar. After 4 weeks, both first premolars were extracted. Each sample was imaged using a microcomputed tomography system (1172; SkyScan, Aartselaar, Belgium) and analyzed with specially designed software for volumetric measurements of resorption craters. Furthermore, pain was evaluated with a visual analog scale for 7 days. There were significant differences in the amounts of root resorption between the control and the experimentally traumatized teeth. No significant difference among the buccal, lingual, mesial, and distal surfaces was found in either jaw. Furthermore, no significant difference existed in the amount of root resorption among the cervical, middle, and apical thirds of both jaws. There was no correlation between age, sex, volume of the root resorption craters, and pain. Restorative buildups, used to increase the vertical dimension by 2 mm for 4 weeks, caused root resorption along the sides of the teeth during the active bite-increase period. Copyright © 2014 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Bonding durability of dual-curing composite core material with different self-etching adhesive systems in a model complete vertical root fracture reconstruction.

PubMed

Waidyasekera, Kanchana; Nikaido, Toru; Weerasinghe, Dinesh; Nurrohman, Hamid; Tagami, Junji

2012-04-01

This study evaluated a dual-curing composite along with different dentin adhesive systems for 1 year under water storage, as a new bonding method of root fragments in complete vertical root fracture. Bovine root fragments were bonded with the dual-curing resin composite Clearfil DC Core Automix (DCA) and one of three adhesive systems: two-step self-etching adhesive Clearfil SE Bond (SE), one-step self-etching adhesive Tokuyama Bond Force (BF), one-step dual-curing self-etching adhesive Clearfil DC Bond (DC). Microtensile bond strength (µTBS)/ultimate tensile bond strength (UTS), FE-SEM ultramorphology of fracture modes, and adhesive dentin interface were observed after water storage for periods of up to one year. The data were analyzed with two-way ANOVA. µTBS was influenced by "dentin adhesive system" (F = 324.455, p < 0.001) and "length of water storage" (F = 8.470, p < 0.001). SE yielded significantly higher µTBS, regardless of storage period (p < 0.05) and maintained the initial µTBS without a significant change after 1 year of water storage (p > 0.05). From 24 h to 1 month, BF showed significantly higher bond strength than DC. UTS of DCA was influenced only by the curing mode of the material (F = 5.051, p = 0.027), but not by the length of water storage (F = 0.053, p > 0.05). Two-step self-etching adhesive systems and dual-curing composite core material can be considered as a suitable bonding method for complete root fractures.

Full-mouth treatment of gingival recessions and noncarious cervical lesions with coronally advanced flap and xenogeneic collagen matrix: 
a 2-year case report.

PubMed

Martiniello, Nello; Stefanini, Martina; Zucchelli, Giovanni

In clinical practice it is common to observe adjacent multiple gingival recessions (MGRs) associated with noncarious cervical lesions (NCCLs). The aim of this 2-year case report was to describe the full-mouth treatment of a patient affected by MGRs and NCCLs, with a combined restorative-surgical approach using a coronally advanced flap (CAF) and a xenogeneic collagen matrix (CM). Before surgery, a composite restoration filled the deepest portion of the NCCL defects and was finished at the level of the maximum root coverage (MRC). The surgical technique adopted for the root coverage procedures was CAF for MGRs without vertical releasing incisions in the maxilla, and with one vertical releasing incision in the mandible. The CM was positioned at the level of the cementoenamel junction (CEJ), and sutured at the base of the anatomic de-epithelialized papillae. The flap was shifted coronally, providing complete coverage of the CM, and sutured coronal to the CEJ with a variable number of sling sutures. At 2 years, complete root coverage was achieved in all treated sites, and the patient reported complete resolution of dental hypersensitivity. In the questionnaire, the patient-reported outcome showed a high level of esthetic satisfaction (mean score: 9.6; range: 9 to 10), and the objective esthetic evaluation with the root coverage esthetic score (RES) system showed a very high result (mean: 9.4). The suggested combined restorative-surgical approach provided successful root coverage and a favorable esthetic outcome in the treatment of MGR associated with NCCLs.

Nitric oxide is involved in phosphorus deficiency-induced cluster root development and citrate exudation in white lupin

USDA-ARS?s Scientific Manuscript database

White lupin (Lupinus albus) forms specialized cluster roots characterized by exudation of organic anions under phosphorus (P) deficiency. Here, we evaluated the role of nitric oxide (NO) in P deficiency-induced cluster-root formation and citrate exudation in white lupin. Plants were treated with NO ...

Rapid changes in protein phosphorylation associated with light-induced gravity perception in corn roots

NASA Technical Reports Server (NTRS)

McFadden, J. J.; Poovaiah, B. W.

1988-01-01

The effect of light and calcium depletion on in vivo protein phosphorylation was tested using dark-grown roots of Merit corn. Light caused rapid and specific promotion of phosphorylation of three polypeptides. Pretreatment of roots with ethylene glycol bis N,N,N',N' tetraacetic acid and A23187 prevented light-induced changes in protein phosphorylation. We postulate that these changes in protein phosphorylation are involved in the light-induced gravity response.

Interactions of light and gravity on growth, orientation, and lignin biosynthesis in mung beans

NASA Technical Reports Server (NTRS)

Jahns, G. C.

1984-01-01

Mung beans (Vigna radiata L.) seedlings grown on the third Space Transport Mission (STS-3) showed marked orientation problems (some of the stems elongated horizontally and many of the roots were growing upward) and had a lower lignin content than the ground based controls. This research was initiated to determine if the atypical growth characteristics of mung beans grown in microgravity could be simulated using horizontal clinostats. Most of the effort focused on the design, construction and testing of the clinostats. In order to closely approximate the growth conditions of the plants grown in the plant growth unit on STS-3, cylindrical lexan minichambers were constructed. Results showed that plants grown using these clinostats in the horizontal position exhibit similar growth characteristics to the plants grown on STS-3 (disorientation of both stems and roots), while the vertical stationary and vertical rotating controls exhibit normal growth.

Diurnal and seasonal variation in root xylem embolism in neotropical savanna woody species: impact on stomatal control of plant water status.

PubMed

Domec, J C; Scholz, F G; Bucci, S J; Meinzer, F C; Goldstein, G; Villalobos-Vega, R

2006-01-01

Vulnerability to water-stress-induced embolism and variation in the degree of native embolism were measured in lateral roots of four co-occurring neotropical savanna tree species. Root embolism varied diurnally and seasonally. Late in the dry season, loss of root xylem conductivity reached 80% in the afternoon when root water potential (psi root) was about -2.6 MPa, and recovered to 25-40% loss of conductivity in the morning when psi root was about -1.0 MPa. Daily variation in psi root decreased, and root xylem vulnerability and capacitance increased with rooting depth. However, all species experienced seasonal minimum psi root close to complete hydraulic failure independent of their rooting depth or resistance to embolism. Predawn psi root was lower than psi soil when psi soil was relatively high (> -0.7 MPa) but became less negative than psi soil, later in the dry season, consistent with a transition from a disequilibrium between plant and soil psi induced by nocturnal transpiration to one induced by hydraulic redistribution of water from deeper soil layers. Shallow longitudinal root incisions external to the xylem prevented reversal of embolism overnight, suggesting that root mechanical integrity was necessary for recovery, consistent with the hypothesis that if embolism is a function of tension, refilling may be a function of internal pressure imbalances. All species shared a common relationship in which maximum daily stomatal conductance declined linearly with increasing afternoon loss of root conductivity over the course of the dry season. Daily embolism and refilling in roots is a common occurrence and thus may be an inherent component of a hydraulic signaling mechanism enabling stomata to maintain the integrity of the hydraulic pipeline in long-lived structures such as stems.

Involvement of heme oxygenase-1 in β-cyclodextrin-hemin complex-induced cucumber adventitious rooting process.

PubMed

Lin, Yuting; Li, Meiyue; Huang, Liqin; Shen, Wenbiao; Ren, Yong

2012-09-01

Our previous results showed that β-cyclodextrin-hemin complex (CDH) exhibited a vital protective role against cadmium-induced oxidative damage and toxicity in alfalfa seedling roots by the regulation of heme oxygenase-1 (HO-1) gene expression. In this report, we further test whether CDH exhibited the hormonal-like response. The application of CDH and an inducer of HO-1, hemin, were able to induce the up-regulation of cucumber HO-1 gene (CsHO1) expression and thereafter the promotion of adventitious rooting in cucumber explants. The effect is specific for HO-1 since the potent HO-1 inhibitor zinc protoporphyrin IX (ZnPP) blocked the above responses triggered by CDH, and the inhibitory effects were reversed further when 30% saturation of CO aqueous solution was added together. Further, molecular evidence showed that CDH triggered the increases of the HO-1-mediated target genes responsible for adventitious rooting, including one DnaJ-like gene (CsDNAJ-1) and two calcium-dependent protein kinase (CDPK) genes (CsCDPK1 and CsCDPK5), and were inhibited by ZnPP and reversed by CO. The calcium (Ca2+) chelator ethylene glycol-bis (2-aminoethylether)-N,N,N',N'-tetraacetic acid (EGTA) and the Ca2+ channel blocker lanthanum chloride (LaCl3) not only compromised the induction of adventitious rooting induced by CDH but also decreased the transcripts of above three target genes. However, the application of ascorbic acid (AsA), a well-known antioxidant in plants, failed to exhibit similar inducible effect on adventitious root formation. In short, above results illustrated that the response of CDH in the induction of cucumber adventitious rooting might be through HO-1-dependent mechanism and calcium signaling. Physiological, pharmacological and molecular evidence showed that β-cyclodextrin-hemin complex (CDH) was able to induce cucumber adventitious rooting through heme oxygenase-1 (HO-1)-dependent mechanism and calcium signaling.

Vegetative growth and cluster development in Shiraz grapevines subjected to partial root-zone cooling

PubMed Central

Rogiers, Suzy Y.; Clarke, Simon J.

2013-01-01

Heterogeneity in root-zone temperature both vertically and horizontally may contribute to the uneven vegetative and reproductive growth often observed across vineyards. An experiment was designed to assess whether the warmed half of a grapevine root zone could compensate for the cooled half in terms of vegetative growth and reproductive development. We divided the root system of potted Shiraz grapevines bilaterally and applied either a cool or a warm treatment to each half from budburst to fruit set. Shoot growth and inflorescence development were monitored over the season. Simultaneous cooling and warming of parts of the root system decreased shoot elongation, leaf emergence and leaf expansion below that of plants with a fully warmed root zone, but not to the same extent as those with a fully cooled root zone. Inflorescence rachis length, flower number and berry number after fertilization were smaller only in those vines exposed to fully cooled root zones. After terminating the treatments, berry enlargement and the onset of veraison were slowed in those vines that had been exposed to complete or partial root-zone cooling. Grapevines exposed to partial root-zone cooling were thus delayed in vegetative and reproductive development, but the inhibition was greater in those plants whose entire root system had been cooled. PMID:24244839

Quantification of root gravitropic response using a constant stimulus feedback system.

PubMed

Wolverton, Chris

2015-01-01

Numerous software packages now exist for quantifying root growth responses, most of which analyze a time resolved sequence of images ex post facto. However, few allow for the real-time analysis of growth responses. The system in routine use in our lab allows for real-time growth analysis and couples this to positional feedback to control the stimulus experienced by the responding root. This combination allows us to overcome one of the confounding variables in studies of root gravity response. Seedlings are grown on standard petri plates attached to a vertical rotating stage and imaged using infrared illumination. The angle of a particular region of the root is determined by image analysis, compared to the prescribed angle, and any corrections in positioning are made by controlling a stepper motor. The system allows for the long-term stimulation of a root at a constant angle and yields insights into the gravity perception and transduction machinery not possible with other approaches.

Micro-CT evaluation of apical delta morphologies in human teeth.

PubMed

Gao, Xianhua; Tay, Franklin R; Gutmann, James L; Fan, Wei; Xu, Ting; Fan, Bing

2016-11-07

The apical delta is an intricate system within the root canal and incompletely debridement may affect the long-term prognosis of root canal therapy. The aim of the present study is to investigate the morphologic features of apical deltas in human teeth with micro-computed tomography (micro-CT) using a centreline-fitting algorithm. One hundred and thirty-six apical deltas were detected in 1400 teeth. Molars had more apical deltas (15.8%) than anterior teeth (6.3%). In maxillary molars, the mesiobuccal root had a significantly higher prevalence of apical delta than the palatal root or the distobuccal root. The median vertical distance of the apical delta was 1.87 mm with 13% more than 3 mm. The median diameter and length of the apical delta branches were 132.3 and 934.5 μm. Apical delta branches were not straight with cross-sectional shapes being non-circular. These morphological features of apical delta may complicate debridement of the infected root canal system.

Antidyslipidemic and Antioxidant Activities of Hibiscus rosa sinensis Root Extract in Alloxan Induced Diabetic Rats.

PubMed

Kumar, Vishnu; Mahdi, Farzana; Khanna, Ashok Kumar; Singh, Ranjana; Chander, Ramesh; Saxena, Jitendra Kumar; Mahdi, Abbas Ali; Singh, Raj Kumar

2013-01-01

The antidyslipidemic activity of Hibiscus rosa sinensis (Malvaceae) root extract has been studied in alloxan induced diabetic rats. In this model, oral administration of root extract (500 mg/kg bw. p.o.) for 15 days resulted in significant decreased in the levels of blood glucose, plasma lipids and reactivated post heparin lipoprotein lipase activity in alloxan induced diabetic rats. Furthermore, the root extract (50-500 μg) when tested for its antioxidant activity, inhibited the generation of super oxide anions and hydroxyl radicals, in both enzymic and non enzymic systems in vitro. The results of the present study demonstrated antidyslipidemic and antioxidant activities in root extract of H. rosa sinensis which could be used in prevention of diabetic-dyslipidemia and related complications.

Phytochromes A and B Mediate Red-Light-Induced Positive Phototropism in Roots1

PubMed Central

Kiss, John Z.; Mullen, Jack L.; Correll, Melanie J.; Hangarter, Roger P.

2003-01-01

The interaction of tropisms is important in determining the final growth form of the plant body. In roots, gravitropism is the predominant tropistic response, but phototropism also plays a role in the oriented growth of roots in flowering plants. In blue or white light, roots exhibit negative phototropism that is mediated by the phototropin family of photoreceptors. In contrast, red light induces a positive phototropism in Arabidopsis roots. Because this red-light-induced response is weak relative to both gravitropism and negative phototropism, we used a novel device to study phototropism without the complications of a counteracting gravitational stimulus. This device is based on a computer-controlled system using real-time image analysis of root growth and a feedback-regulated rotatable stage. Our data show that this system is useful to study root phototropism in response to red light, because in wild-type roots, the maximal curvature detected with this apparatus is 30° to 40°, compared with 5° to 10° without the feedback system. In positive root phototropism, sensing of red light occurs in the root itself and is not dependent on shoot-derived signals resulting from light perception. Phytochrome (Phy)A and phyB were severely impaired in red-light-induced phototropism, whereas the phyD and phyE mutants were normal in this response. Thus, PHYA and PHYB play a key role in mediating red-light-dependent positive phototropism in roots. Although phytochrome has been shown to mediate phototropism in some lower plant groups, this is one of the few reports indicating a phytochrome-dependent phototropism in flowering plants. PMID:12644690

Isolation of bergenin from the root bark of Securinega virosa and evaluation of its potential sleep promoting effect.

PubMed

Magaji, Mohammed Garba; Musa, Aliyu Muhammad; Abdullahi, Musa Ismail; Ya'u, Jamilu; Hussaini, Isa Marte

2015-01-01

Securinega virosa Roxb (Ex Willd) Baill (Euphorbaiceae) root bark has been reportedly used in African traditional medicine in the management of mental illnesses. Previously, the sleep-inducing potential of the crude methanol root bark of Securinega virosa extract and its butanol fraction have been reported. The study aimed to isolate and characterize the bioactive constituent that may be responsible for the sleep inducing property of the root of the plant. The phytochemical investigation of the S. virosa root bark was carried out leading to the isolation of a compound from the butanol-soluble fraction of the methanol extract. The structure of the compound was elucidated on the basis of its spectral data, including IR, 1D and 2D NMR, mass spectrometry as well as X-ray diffraction analysis. The compound was investigated for sleep-inducing potential using diazepam-induced sleeping time test and beam walking assay in mice. This is the first report on the isolation of bergenin from the root of the plant. It significantly decreased the mean onset of sleep [F (2, 15) =7.167; p< 0.01] at the dose of 10 mg/kg, without significantly affecting the total sleep duration [F (2, 15) = 0.090, p=0.914]. Conversely, it did not significantly affect the number of foot slips at the doses of 5 and 10 mg/kg tested. Bergenin isolated from the root bark of S. virosa possesses sleep-inducing property and could be partly responsible for the sedative potential of the root of S. virosa.

Costs of jasmonic acid induced defense in aboveground and belowground parts of corn (Zea mays L.).

PubMed

Feng, Yuanjiao; Wang, Jianwu; Luo, Shiming; Fan, Huizhi; Jin, Qiong

2012-08-01

Costs of jasmonic acid (JA) induced plant defense have gained increasing attention. In this study, JA was applied continuously to the aboveground (AG) or belowground (BG) parts, or AG plus BG parts of corn (Zea mays L.) to investigate whether JA exposure in one part of the plant would affect defense responses in another part, and whether or not JA induced defense would incur allocation costs. The results indicated that continuous JA application to AG parts systemically affected the quantities of defense chemicals in the roots, and vice versa. Quantities of DIMBOA and total amounts of phenolic compounds in leaves or roots generally increased 2 or 4 wk after the JA treatment to different plant parts. In the first 2 wk after application, the increase of defense chemicals in leaves and roots was accompanied by a significant decrease of root length, root surface area, and root biomass. Four weeks after the JA application, however, no such costs for the increase of defense chemicals in leaves and roots were detected. Instead, shoot biomass and root biomass increased. The results suggest that JA as a defense signal can be transferred from AG parts to BG parts of corn, and vice versa. Costs for induced defense elicited by continuous JA application were found in the early 2 wk, while distinct benefits were observed later, i.e., 4 wk after JA treatment.

Plant and Insect Viruses in Managed and Natural Environments: Novel and Neglected Transmission Pathways.

PubMed

Jones, Roger A C

2018-01-01

The capacity to spread by diverse transmission pathways enhances a virus' ability to spread effectively and survive when circumstances change. This review aims to improve understanding of how plant and insect viruses spread through natural and managed environments by drawing attention to 12 novel or neglected virus transmission pathways whose contribution is underestimated. For plant viruses, the pathways reviewed are vertical and horizontal transmission via pollen, and horizontal transmission by parasitic plants, natural root grafts, wind-mediated contact, chewing insects, and contaminated water or soil. For insect viruses, they are transmission by plants serving as passive "vectors," arthropod vectors, and contamination of pollen and nectar. Based on current understanding of the spatiotemporal dynamics of virus spread, the likely roles of each pathway in creating new primary infection foci, enlarging previously existing infection foci, and promoting generalized virus spread are estimated. All pathways except transmission via parasitic plants, root grafts, and wind-mediated contact transmission are likely to produce new primary infection foci. All 12 pathways have the capability to enlarge existing infection foci, but only to a limited extent when spread occurs via virus-contaminated soil or vertical pollen transmission. All pathways except those via parasitic plant, root graft, contaminated soil, and vertical pollen transmission likely contribute to generalized virus spread, but to different extents. For worst-case scenarios, where mixed populations of host species occur under optimal virus spread conditions, the risk that host species jumps or virus emergence events will arise is estimated to be "high" for all four insect virus pathways considered, and, "very high" or "moderate" for plant viruses transmitted by parasitic plant and root graft pathways, respectively. To establish full understanding of virus spread and thereby optimize effective virus disease management, it is important to examine all transmission pathways potentially involved, regardless of whether the virus' ecology is already presumed to be well understood or otherwise. © 2018 Elsevier Inc. All rights reserved.

Dynamic Torque and Vertical Force Analysis during Nickel-titanium Rotary Root Canal Preparation with Different Modes of Reciprocal Rotation.

PubMed

Tokita, Daisuke; Ebihara, Arata; Nishijo, Miki; Miyara, Kana; Okiji, Takashi

2017-10-01

The purpose of the present study was to compare 2 modes of reciprocal movement (torque-sensitive and time-dependent reciprocal rotation) with continuous rotation in terms of torque and apical force generation during nickel-titanium rotary root canal instrumentation. A custom-made automated root canal instrumentation and torque/force analyzing device was used to prepare simulated canals in resin blocks and monitor the torque and apical force generated in the blocks during preparation. Experimental groups (n = 7, each) consisted of (1) torque-sensitive reciprocal rotation with torque-sensitive vertical movement (group TqR), (2) time-dependent reciprocal rotation with time-dependent vertical movement (group TmR), and (3) continuous rotation with time-dependent vertical movement (group CR). The canals were instrumented with TF Adaptive SM1 and SM2 rotary files (SybronEndo, Orange, CA), and the torque and apical force were measured during instrumentation with SM2. The mean and maximum torque and apical force values were statistically analyzed using 1-way analysis of variance and the Tukey test (α = 0.05). The recordings showed intermittent increases of upward apical force and clockwise torque, indicating the generation and release of screw-in forces. The maximum upward apical force values in group TmR were significantly smaller than those in group CR (P < .05). The maximum torque values in clockwise and counterclockwise directions in groups TqR and TmR were significantly smaller than those in group CR (P < .05). Under the present experimental conditions using TF Adaptive instruments, both torque-sensitive and time-dependent reciprocal rotation generated significantly lower maximum torque and may have advantages in reducing stress generation caused by screw-in forces when compared with continuous rotation. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Effects of phosphorus supply on growth, phosphate concentration and cluster-root formation in three Lupinus species

PubMed Central

Abdolzadeh, Ahmad; Wang, Xing; Veneklaas, Erik J.; Lambers, Hans

2010-01-01

Background and Aims In some lupin species, phosphate deficiency induces cluster-root formation, which enhances P uptake by increasing root surface area and, more importantly, the release of root exudates which enhances P availability. Methods Three species of Lupinus, L. albus, L. atlanticus and L. micranthus, with inherently different relative growth rates were cultivated under hydroponics in a greenhouse at four phosphate concentrations (1, 10, 50 and 150 µm) to compare the role of internal P in regulating cluster-root formation. Key Results The highest growth rate was observed in L. atlanticus, followed by L. albus and L. micranthus. At 1 µm P, cluster-root formation was markedly induced in all three species. The highest P uptake and accumulation was observed in L. micranthus, followed by L. atlanticus and then L. albus. Inhibition of cluster-root formation was severe at 10 µm P in L. atlanticus, but occurred stepwise with increasing P concentration in the root medium in L. albus. Conclusions In L. atlanticus and L. albus cluster-root formation was suppressed by P treatments above 10 µm, indicating a P-inducible regulating system for cluster-root formation, as expected. By contrast, production of cluster roots in L. micranthus, in spite of a high internal P concentration, indicated a lower sensitivity to P status, which allowed P-toxicity symptoms to develop. PMID:20037142

Ammonium affects cell viability to inhibit root growth in Arabidopsis * #

PubMed Central

Qin, Cheng; Yi, Ke-ke; Wu, Ping

2011-01-01

Ammonium (NH4 +) is an important form of nitrogen nutrient for most plants, yet is also a stressor for many of them. However, the primary events of NH4 + toxicity at the cellular level are still unclear. Here, we showed that NH4 + toxicity can induce the root cell death in a temporal pattern which primarily occurs in the cells of root maturation and elongation zones, and then spreads to the cells in the meristem and root cap. The results from the NH4 +-hypersensitive mutant hsn1 further confirmed our findings. Taken together, NH4 + toxicity inhibits primary root growth by inhibiting cell elongation and division and inducing root cell death. PMID:21634041

Drought-induced changes in root biomass largely result from altered root morphological traits: evidence from a synthesis of global field trials.

PubMed

Zhou, Guiyao; Zhou, Xuhui; Nie, Yuanyuan; Bai, Shahla Hosseini; Zhou, Lingyan; Shao, Junjiong; Cheng, Weisong; Wang, Jiawei; Hu, Fengqin; Fu, Yuling

2018-06-07

Extreme drought is likely to become more frequent and intense as a result of global climate change, which may significantly impact plant root traits and responses (i.e., morphology, production, turnover, and biomass). However, a comprehensive understanding of how drought affects root traits and responses remains elusive. Here, we synthesized data from 128 published studies under field conditions to examine the responses of 17 variables associated with root traits to drought. Our results showed that drought significantly decreased root length and root length density by 38.29% and 11.12%, respectively, but increased root diameter by 3.49%. However, drought significantly increased root: shoot mass ratio and root cortical aerenchyma by 13.54% and 90.7%, respectively. Our results suggest that drought significantly modified root morphological traits and increased root mortality, and the drought-induced decrease in root biomass was less than shoot biomass, causing higher root: shoot mass ratio. The cascading effects of drought on root traits and responses may need to be incorporated into terrestrial biosphere models to improve prediction of the climate-biosphere feedback. This article is protected by copyright. All rights reserved.

Geoperception in primary and lateral roots of Phaseolus vulgaris (Fabaceae). III. A model to explain the differential georesponsiveness of primary and lateral roots

NASA Technical Reports Server (NTRS)

Ransom, J. S.; Moore, R.

1985-01-01

Half-tipped primary and lateral roots of Phaseolus vulgaris bend toward the side of the root on which the intact half tip remains. Therefore, tips of lateral and primary roots produce growth effectors capable of inducing gravicurvature. The asymmetrical placement of a tip of a lateral root onto a detipped primary root results in the root bending toward the side of the root onto which the tip was placed. That is, the lesser graviresponsiveness of lateral roots as compared with primary roots is not due to the inability of their caps to produce growth inhibitors. The more pronounced graviresponsiveness of primary roots is positively correlated with the presence of columella tissues that are 3.8 times longer, 1.7 times wider, and 10.5 times more voluminous than the columellas of lateral roots. We propose that the lack of graviresponsiveness exhibited by lateral roots is due to the fact that they (i) produce smaller amounts of the inhibitor than primary (i.e., strongly graviresponsive) roots and (ii) are unable to redistribute the inhibitor so as to be able to create a concentration gradient sufficient to induce a pronounced gravitropic response.

Physical properties of root cementum: part 20. Effect of fluoride on orthodontically induced root resorption with light and heavy orthodontic forces for 4 weeks: a microcomputed tomography study.

PubMed

Karadeniz, Ersan Ilsay; Gonzales, Carmen; Nebioglu-Dalci, Oyku; Dwarte, Dennis; Turk, Tamer; Isci, Devrim; Sahin-Saglam, Aynur M; Alkis, Huseyin; Elekdag-Turk, Selma; Darendeliler, M Ali

2011-11-01

The major side effect of orthodontic treatment is orthodontically induced inflammatory root resorption. Fluoride was previously shown to reduce the volume of the root resorption craters in rats. However, the effect of fluoride on orthodontically induced inflammatory root resorption in humans has not yet been investigated. The aim of this study was to investigate the effect of high and low amounts of fluoride intake from birth on orthodontically induced inflammatory root resorption under light (25 g) and heavy (225 g) force applications. Forty-eight patients who required maxillary premolar extractions as part of their orthodontic treatment were selected from 2 cities in Turkey with high and low fluoride concentrations in the public water of ≥ 2 and ≤ 0.05 ppm, respectively. The patients were randomly separated into 4 groups of 12 each: group 1, high fluoride intake and heavy force; group 2, low fluoride intake and heavy force; group 3, high fluoride intake and light force; and group 4, low fluoride intake and light force. Light or heavy buccal tipping orthodontic forces were applied on the maxillary first premolars for 28 days. At day 28, the teeth were extracted, and the samples were analyzed with microcomputed tomography. Fluoride reduced the volume of root resorption craters in all groups; however, this effect was significantly different with high force application (P = 0.015). It was also found that light forces caused less root resorption than heavy forces. There was no statistical difference in the amount of root resorption observed on root surfaces (buccal, lingual, mesial, and distal) in all groups. However, the middle third of the roots showed the least root resorption. With high fluoride intake and heavy force application, less root resorption was found in all root surfaces and root thirds. Fluoride may reduce the volume of root resorption craters. This effect is significant with heavy force applications (P <0.05). The cervical and apical thirds of the root showed significantly greater root resorption after the application of buccal tipping force for 4 weeks. Copyright © 2011 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Rhodamine B induces long nucleoplasmic bridges and other nuclear anomalies in Allium cepa root tip cells.

PubMed

Tan, Dehong; Bai, Bing; Jiang, Donghua; Shi, Lin; Cheng, Shunchang; Tao, Dongbing; Ji, Shujuan

2014-03-01

The cytogenetic toxicity of rhodamine B on root tip cells of Allium cepa was investigated. A. cepa were cultured in water (negative control), 10 ppm methyl methanesulfonate (positive control), and three concentrations of rhodamine B (200, 100, and 50 ppm) for 7 days. Rhodamine B inhibited mitotic activity; increased nuclear anomalies, including micronuclei, nuclear buds, and bridged nuclei; and induced oxidative stress in A. cepa root tissues. Furthermore, a substantial amount of long nucleoplasmic bridges were entangled together, and some nuclei were simultaneously linked to several other nuclei and to nuclear buds with nucleoplasmic bridges in rhodamine B-treated cells. In conclusion, rhodamine B induced cytogenetic effects in A. cepa root tip cells, which suggests that the A. cepa root is an ideal model system for detecting cellular interactions.

Root distributions of Eurotia lanata in association with two species of agropyron on disturbed soils

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bonham, C.D.; Mack, S.E.

1990-12-01

Root distributions of Eurotia lanata in association with Agropyron inerme and A. smithii on soils that were mechanically disturbed were studied. Root diagrams and measurements were made for plants in competitive pairs from soils representing two depths of soil disturbance (30 cm and 1 m) and control areas. Soil disturbance was observed to reduce significantly depth of root penetration and root concentration of E. lanata. Root depth, maximum lateral spread of roots, and zone of root concentration of E. lanata plants were greatest in pure stand pairs. Eurotia lanata associated with A. inerme had the smallest root concentration. The areamore » occupied by E. lanata roots was 59% greater in pure stands than when found adjacent to A. inerme. Agropyron inerme apparently used more available soil water in the top 20 cm of soil than did the shrub and resulted in reduced root growth for E. lanata. On the other hand, the asexual reproductive strategy of A. smithii, where roots and rhizomes were distributed both vertically and laterally, enables the grass species to minimize detrimental effects of its association with E. lanata. The results have important implications for selection of species combinations to reseed disturbed soils in semiarid or arid environments. In particular, attention should be given to use of species that have differing specializations as indicated by their growth and morphology.« less

Induction of curvature in maize roots by calcium or by thigmostimulation: role of the postmitotic isodiametric growth zone

NASA Technical Reports Server (NTRS)

Ishikawa, H.; Evans, M. L.

1992-01-01

We examined the response of primary roots of maize (Zea mays L. cv Merit) to unilateral application of calcium with particular attention to the site of application, the dependence on growth rate, and possible contributions of thigmotropic stimulation during application. Unilateral application of agar to the root cap induced negative curvature whether or not the agar contained calcium. This apparent thigmotropic response was enhanced by including calcium in the agar. Curvature away from objects applied unilaterally to the extreme root tip occurred both in intact and detipped roots. When agar containing calcium chloride was applied to one side of the postmitotic isodiametric growth zone ( a region between the apical meristem and the elongation zone), the root curved toward the side of application. This response could not be induced by plain agar. We conclude that curvature away from calcium applied to the root tip results from a thigmotropic response to stimulation during application. In contrast, curvature toward the calcium applied to the postmitotic isodiametric growth zone results from direct calcium-induced inhibition of growth.

The effects of dan-shen root on cardiomyogenic differentiation of human placenta-derived mesenchymal stem cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Kun; Li, Shi-zheng, E-mail: ychozon@yahoo.com.cn; Zhang, Yun-li

2011-11-11

Highlights: Black-Right-Pointing-Pointer Conditional medium and dan-shen root were used for cardiomyogenic differentiation. Black-Right-Pointing-Pointer They all could induce hPDMSCs to differentiate into cardiomyocytes. Black-Right-Pointing-Pointer The induction effect of the latter was slightly higher compared to that of the former. Black-Right-Pointing-Pointer Dan-shen root could be a good inducer for cardiomyogenic differentiation. -- Abstract: The aim of this study was to search for a good inducer agent using for cardiomyogenic differentiation of stem cells. Human placenta-derived mesenchymal stem cells (hPDMSCs) were isolated and incubated in enriched medium. Fourth passaged cells were treated with 10 mg/L dan-shen root for 20 days. Morphologic characteristics weremore » analyzed by confocal and electron microscopy. Expression of {alpha}-sarcomeric actin was analyzed by immunohistochemistry. Expression of cardiac troponin-I (TnI) was analyzed by immunohistofluorescence. Atrial natriuretic factor (ANF) and beta-myocin heavy chain ({beta}-MHC) were detected by reverse transcriptase polymerase chain reaction (RT-PCR). hPDMSCs treated with dan-shen root gradually formed a stick-like morphology and connected with adjoining cells. On the 20th day, most of the induced cells stained positive with {alpha}-sarcomeric actin and TnI antibody. ANF and {beta}-MHC were also detected in the induced cells. Approximately 80% of the cells were successfully transdifferentiated into cardiomyocytes. In conclusion, dan-shen root is a good inducer agent used for cardiomyogenic differentiation of hPDMSCs.« less

Precision engineering: an evolutionary perspective.

PubMed

Evans, Chris J

2012-08-28

Precision engineering is a relatively new name for a technology with roots going back over a thousand years; those roots span astronomy, metrology, fundamental standards, manufacturing and money-making (literally). Throughout that history, precision engineers have created links across disparate disciplines to generate innovative responses to society's needs and wants. This review combines historical and technological perspectives to illuminate precision engineering's current character and directions. It first provides us a working definition of precision engineering and then reviews the subject's roots. Examples will be given showing the contributions of the technology to society, while simultaneously showing the creative tension between the technological convergence that spurs new directions and the vertical disintegration that optimizes manufacturing economics.

Organization of cortical microtubules in graviresponding maize roots

NASA Technical Reports Server (NTRS)

Blancaflor, E. B.; Hasenstein, K. H.

1993-01-01

Immunofluorescence labeling of cortical microtubules (MTs) was used to investigate the relationship between MT arrangement and changes in growth rate of the upper and lower sides of horizontally placed roots of maize (Zea mays L. cv. Merit). Cap cells and cells of the elongation zone of roots grown vertically in light or darkness showed MT arrangements that were transverse (perpendicular) to the growth direction. Microtubules of cells basal to the elongation zone typically showed oblique orientation. Two hours after horizontal reorientation, cap cells of gravicompetent, light-grown and curving roots contained MTs parallel to the gravity vector. The MT arrangement on the upper side of the elongation zone remained transverse but the MTs of the outer four to five layers of cortical cells along the lower side of the elongation zone showed reorientation parallel to the axis of the root. The MTs of the lower epidermis retained their transverse orientation. Dark-grown roots did not curve and did not show reorientation of MTs in cells of the root cap or elongation zone. The data indicate that MT depolymerization and reorientation is correlated with reduction in growth rate, and that MT reorientation is one of the steps of growth control of graviresponding roots.

Natural Variation in Small Molecule–Induced TIR-NB-LRR Signaling Induces Root Growth Arrest via EDS1- and PAD4-Complexed R Protein VICTR in Arabidopsis[C][W

PubMed Central

Kim, Tae-Houn; Kunz, Hans-Henning; Bhattacharjee, Saikat; Hauser, Felix; Park, Jiyoung; Engineer, Cawas; Liu, Amy; Ha, Tracy; Parker, Jane E.; Gassmann, Walter; Schroeder, Julian I.

2012-01-01

In a chemical genetics screen we identified the small-molecule [5-(3,4-dichlorophenyl)furan-2-yl]-piperidine-1-ylmethanethione (DFPM) that triggers rapid inhibition of early abscisic acid signal transduction via PHYTOALEXIN DEFICIENT4 (PAD4)- and ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1)-dependent immune signaling mechanisms. However, mechanisms upstream of EDS1 and PAD4 in DFPM-mediated signaling remain unknown. Here, we report that DFPM generates an Arabidopsis thaliana accession-specific root growth arrest in Columbia-0 (Col-0) plants. The genetic locus responsible for this natural variant, VICTR (VARIATION IN COMPOUND TRIGGERED ROOT growth response), encodes a TIR-NB-LRR (for Toll-Interleukin1 Receptor–nucleotide binding–Leucine-rich repeat) protein. Analyses of T-DNA insertion victr alleles showed that VICTR is necessary for DFPM-induced root growth arrest and inhibition of abscisic acid–induced stomatal closing. Transgenic expression of the Col-0 VICTR allele in DFPM-insensitive Arabidopsis accessions recapitulated the DFPM-induced root growth arrest. EDS1 and PAD4, both central regulators of basal resistance and effector-triggered immunity, as well as HSP90 chaperones and their cochaperones RAR1 and SGT1B, are required for the DFPM-induced root growth arrest. Salicylic acid and jasmonic acid signaling pathway components are dispensable. We further demonstrate that VICTR associates with EDS1 and PAD4 in a nuclear protein complex. These findings show a previously unexplored association between a TIR-NB-LRR protein and PAD4 and identify functions of plant immune signaling components in the regulation of root meristematic zone-targeted growth arrest. PMID:23275581

Root Damage under Alkaline Stress Is Associated with Reactive Oxygen Species Accumulation in Rice (Oryza sativa L.)

PubMed Central

Zhang, Hui; Liu, Xiao-Long; Zhang, Rui-Xue; Yuan, Hai-Yan; Wang, Ming-Ming; Yang, Hao-Yu; Ma, Hong-Yuan; Liu, Duo; Jiang, Chang-Jie; Liang, Zheng-Wei

2017-01-01

Alkaline stress (high pH) severely damages root cells, and consequently, inhibits rice (Oryza sativa L.) seedling growth. In this study, we demonstrate the accumulation of reactive oxygen species (ROS) in root cells under alkaline stress. Seedlings of two rice cultivars with different alkaline tolerances, ‘Dongdao-4’ (moderately alkaline-tolerant) and ‘Jiudao-51’ (alkaline-sensitive), were subjected to alkaline stress simulated by 15 mM sodium carbonate (Na2CO3). Alkaline stress greatly reduced seedling survival rate, shoot and root growth, and root vigor. Moreover, severe root cell damage was observed under alkaline stress, as shown by increased membrane injury, malondialdehyde accumulation, and Evan’s Blue staining. The expression of the cell death-related genes OsKOD1, OsHsr203j, OsCP1, and OsNAC4 was consistently upregulated, while that of a cell death-suppressor gene, OsBI1, was downregulated. Analysis of the ROS contents revealed that alkaline stress induced a marked accumulation of superoxide anions (O2•-) and hydrogen peroxide (H2O2) in rice roots. The application of procyanidins (a potent antioxidant) to rice seedlings 24 h prior to alkaline treatment significantly alleviated alkalinity-induced root damage and promoted seedling growth inhibition, which were concomitant with reduced ROS accumulation. These results suggest that root cell damage, and consequently growth inhibition, of rice seedlings under alkaline stress is closely associated with ROS accumulation. The antioxidant activity of superoxide dismutase, catalase, peroxidase, and ascorbate peroxidase increased under alkaline stress in the roots, probably in response to the cellular damage induced by oxidative stress. However, this response mechanism may be overwhelmed by the excess ROS accumulation observed under stress, resulting in oxidative damage to root cells. Our findings provide physiological insights into the molecular mechanisms of alkalinity-induced damage to root cells, and will contribute to the improvement of alkaline stress tolerance in rice plants. PMID:28943882

Root Damage under Alkaline Stress Is Associated with Reactive Oxygen Species Accumulation in Rice (Oryza sativa L.).

PubMed

Zhang, Hui; Liu, Xiao-Long; Zhang, Rui-Xue; Yuan, Hai-Yan; Wang, Ming-Ming; Yang, Hao-Yu; Ma, Hong-Yuan; Liu, Duo; Jiang, Chang-Jie; Liang, Zheng-Wei

2017-01-01

Alkaline stress (high pH) severely damages root cells, and consequently, inhibits rice ( Oryza sativa L.) seedling growth. In this study, we demonstrate the accumulation of reactive oxygen species (ROS) in root cells under alkaline stress. Seedlings of two rice cultivars with different alkaline tolerances, 'Dongdao-4' (moderately alkaline-tolerant) and 'Jiudao-51' (alkaline-sensitive), were subjected to alkaline stress simulated by 15 mM sodium carbonate (Na 2 CO 3 ). Alkaline stress greatly reduced seedling survival rate, shoot and root growth, and root vigor. Moreover, severe root cell damage was observed under alkaline stress, as shown by increased membrane injury, malondialdehyde accumulation, and Evan's Blue staining. The expression of the cell death-related genes OsKOD1 , OsHsr203j , OsCP1 , and OsNAC4 was consistently upregulated, while that of a cell death-suppressor gene, OsBI1 , was downregulated. Analysis of the ROS contents revealed that alkaline stress induced a marked accumulation of superoxide anions ([Formula: see text]) and hydrogen peroxide (H 2 O 2 ) in rice roots. The application of procyanidins (a potent antioxidant) to rice seedlings 24 h prior to alkaline treatment significantly alleviated alkalinity-induced root damage and promoted seedling growth inhibition, which were concomitant with reduced ROS accumulation. These results suggest that root cell damage, and consequently growth inhibition, of rice seedlings under alkaline stress is closely associated with ROS accumulation. The antioxidant activity of superoxide dismutase, catalase, peroxidase, and ascorbate peroxidase increased under alkaline stress in the roots, probably in response to the cellular damage induced by oxidative stress. However, this response mechanism may be overwhelmed by the excess ROS accumulation observed under stress, resulting in oxidative damage to root cells. Our findings provide physiological insights into the molecular mechanisms of alkalinity-induced damage to root cells, and will contribute to the improvement of alkaline stress tolerance in rice plants.

Bimodal effect of hydrogen peroxide and oxidative events in nitrite-induced rapid root abscission by the water fern Azolla pinnata

DOE PAGES

Cohen, Michael F.; Gurung, Sushma; Birarda, Giovanni; ...

2015-07-09

In the genus Azolla rapid abscission of roots from floating fronds occurs within minutes in response to a variety of stresses, including exposure to nitrite. We found that hydrogen peroxide, though itself not an inducer of root abscission, modulates nitrite-induced root abscission by Azolla pinnata in a dose-dependent manner, with 2 mM H 2O 2 significantly diminishing the responsiveness to 2 mM NaNO 2, and 10 mM H 2O 2 slightly enhancing it. Hypoxia, which has been found in other plants to result in autogenic production of H 2O 2, dramatically stimulated root abscission of A. pinnata in response tomore » nitrite, especially for plants previously cultivated in medium containing 5 mM KNO 3 compared to plants cultivated under N 2-fixing conditions without combined nitrogen. Plants, including Azolla, produce the small signaling molecule nitric oxide (NO) from nitrite using nitrate reductase. We found Azolla plants to display dose-dependent root abscission in response to the NO donor spermine NONOate. Treatment of plants with the thiol-modifying agents S-methyl methanethiosulfonate or glutathione inhibited the nitrite-induced root abscission response. Synchrotron radiation-based Fourier transform infrared spectromicroscopy revealed higher levels of carbonylation in the abscission zone of dropped roots, indicative of reaction products of polysaccharides with potent free radical oxidants. Lastly, we hypothesize that metabolic products of nitrite and NO react with H 2O 2 in the apoplast leading to free-radical-mediated cleavage of structural polysaccharides and consequent rapid root abscission.« less

Bimodal effect of hydrogen peroxide and oxidative events in nitrite-induced rapid root abscission by the water fern Azolla pinnata.

PubMed

Cohen, Michael F; Gurung, Sushma; Birarda, Giovanni; Holman, Hoi-Ying N; Yamasaki, Hideo

2015-01-01

In the genus Azolla rapid abscission of roots from floating fronds occurs within minutes in response to a variety of stresses, including exposure to nitrite. We found that hydrogen peroxide, though itself not an inducer of root abscission, modulates nitrite-induced root abscission by Azolla pinnata in a dose-dependent manner, with 2 mM H2O2 significantly diminishing the responsiveness to 2 mM NaNO2, and 10 mM H2O2 slightly enhancing it. Hypoxia, which has been found in other plants to result in autogenic production of H2O2, dramatically stimulated root abscission of A. pinnata in response to nitrite, especially for plants previously cultivated in medium containing 5 mM KNO3 compared to plants cultivated under N2-fixing conditions without combined nitrogen. Plants, including Azolla, produce the small signaling molecule nitric oxide (NO) from nitrite using nitrate reductase. We found Azolla plants to display dose-dependent root abscission in response to the NO donor spermine NONOate. Treatment of plants with the thiol-modifying agents S-methyl methanethiosulfonate or glutathione inhibited the nitrite-induced root abscission response. Synchrotron radiation-based Fourier transform infrared spectromicroscopy revealed higher levels of carbonylation in the abscission zone of dropped roots, indicative of reaction products of polysaccharides with potent free radical oxidants. We hypothesize that metabolic products of nitrite and NO react with H2O2 in the apoplast leading to free-radical-mediated cleavage of structural polysaccharides and consequent rapid root abscission.

Bimodal effect of hydrogen peroxide and oxidative events in nitrite-induced rapid root abscission by the water fern Azolla pinnata

PubMed Central

Cohen, Michael F.; Gurung, Sushma; Birarda, Giovanni; Holman, Hoi-Ying N.; Yamasaki, Hideo

2015-01-01

In the genus Azolla rapid abscission of roots from floating fronds occurs within minutes in response to a variety of stresses, including exposure to nitrite. We found that hydrogen peroxide, though itself not an inducer of root abscission, modulates nitrite-induced root abscission by Azolla pinnata in a dose-dependent manner, with 2 mM H2O2 significantly diminishing the responsiveness to 2 mM NaNO2, and 10 mM H2O2 slightly enhancing it. Hypoxia, which has been found in other plants to result in autogenic production of H2O2, dramatically stimulated root abscission of A. pinnata in response to nitrite, especially for plants previously cultivated in medium containing 5 mM KNO3 compared to plants cultivated under N2-fixing conditions without combined nitrogen. Plants, including Azolla, produce the small signaling molecule nitric oxide (NO) from nitrite using nitrate reductase. We found Azolla plants to display dose-dependent root abscission in response to the NO donor spermine NONOate. Treatment of plants with the thiol-modifying agents S-methyl methanethiosulfonate or glutathione inhibited the nitrite-induced root abscission response. Synchrotron radiation-based Fourier transform infrared spectromicroscopy revealed higher levels of carbonylation in the abscission zone of dropped roots, indicative of reaction products of polysaccharides with potent free radical oxidants. We hypothesize that metabolic products of nitrite and NO react with H2O2 in the apoplast leading to free-radical-mediated cleavage of structural polysaccharides and consequent rapid root abscission. PMID:26217368

Genomic Regions Influencing Seminal Root Traits in Barley.

PubMed

Robinson, Hannah; Hickey, Lee; Richard, Cecile; Mace, Emma; Kelly, Alison; Borrell, Andrew; Franckowiak, Jerome; Fox, Glen

2016-03-01

Water availability is a major limiting factor for crop production, making drought adaptation and its many component traits a desirable attribute of plant cultivars. Previous studies in cereal crops indicate that root traits expressed at early plant developmental stages, such as seminal root angle and root number, are associated with water extraction at different depths. Here, we conducted the first study to map seminal root traits in barley ( L.). Using a recently developed high-throughput phenotyping method, a panel of 30 barley genotypes and a doubled-haploid (DH) population (ND24260 × 'Flagship') comprising 330 lines genotyped with diversity array technology (DArT) markers were evaluated for seminal root angle (deviation from vertical) and root number under controlled environmental conditions. A high degree of phenotypic variation was observed in the panel of 30 genotypes: 13.5 to 82.2 and 3.6 to 6.9° for root angle and root number, respectively. A similar range was observed in the DH population: 16.4 to 70.5 and 3.6 to 6.5° for root angle and number, respectively. Seven quantitative trait loci (QTL) for seminal root traits (root angle, two QTL; root number, five QTL) were detected in the DH population. A major QTL influencing both root angle and root number (/) was positioned on chromosome 5HL. Across-species analysis identified 10 common genes underlying root trait QTL in barley, wheat ( L.), and sorghum [ (L.) Moench]. Here, we provide insight into seminal root phenotypes and provide a first look at the genetics controlling these traits in barley. Copyright © 2016 Crop Science Society of America.

Quantifying root-reinforcement of river bank soils by four Australian tree species

NASA Astrophysics Data System (ADS)

Docker, B. B.; Hubble, T. C. T.

2008-08-01

The increased shear resistance of soil due to root-reinforcement by four common Australian riparian trees, Casuarina glauca, Eucalyptus amplifolia, Eucalyptus elata and Acacia floribunda, was determined in-situ with a field shear-box. Root pull-out strengths and root tensile-strengths were also measured and used to evaluate the utility of the root-reinforcement estimation models that assume simultaneous failure of all roots at the shear plane. Field shear-box results indicate that tree roots fail progressively rather than simultaneously. Shear-strengths calculated for root-reinforced soil assuming simultaneous root failure, yielded values between 50% and 215% higher than directly measured shear-strengths. The magnitude of the overestimate varies among species and probably results from differences in both the geometry of the root-system and tensile strengths of the root material. Soil blocks under A. floribunda which presents many, well-spread, highly-branched fine roots with relatively higher tensile strength, conformed most closely with root model estimates; whereas E. amplifolia, which presents a few, large, unbranched vertical roots, concentrated directly beneath the tree stem and of relatively low tensile strength, deviated furthest from model-estimated shear-strengths. These results suggest that considerable caution be exercised when applying estimates of increased shear-strength due to root-reinforcement in riverbank stability modelling. Nevertheless, increased soil shear strength provided by tree roots can be calculated by knowledge of the Root Area Ratio ( RAR) at the shear plane. At equivalent RAR values, A. floribunda demonstrated the greatest earth reinforcement potential of the four species studied.

Hormonal regulation of gravitropic bending

NASA Astrophysics Data System (ADS)

Hu, X.; Cui, D.; Xu, X.; Hu, L.; Cai, W.

Gravitropic bending is an important subject in the research of plant Recent data support the basics of the Cholodny-Went hypothesis indicating that differential growth in gravitropism is due to redistribution of auxin to the lower sides of gravistimulated roots but little is known regarding the molecular details of such effects So we carried a series of work surround the signals induced by auxin end center We found the endogenous signaling molecules nitric oxide NO and cGMP mediate responses to gravistimulation in primary roots of soybean Glycine max Horizontal orientation of soybean roots caused the accumulation of both NO and cGMP in the primary root tip Fluorescence confocal microcopy revealed that the accumulation of NO was asymmetric with NO concentrating in the lower side of the root Auxin induced NO accumulation in root protoplasts and asymmetric NO accumulation in root tips Gravistimulation NO and auxin also induced the accumulation of cGMP a response inhibited by removal of NO or by inhibitors of guanylyl cyclase compounds that also reduced gravitropic bending Asymmetric NO accumulation and gravitropic bending were both inhibited by an auxin transport inhibitor and the inhibition of bending was overcome by treatment with NO or 8-bromo-cGMP a cell-permeable analog of cGMP These data indicate that auxin-induced NO and cGMP mediate gravitropic curvature in soybean roots From Hu et al Plant Physiol 2005 137 663-670 The asymmetric distribution of auxin plays a fundamental role in plant gravitropic bending

Exogenous nitrate induces root branching and inhibits primary root growth in Capsicum chinense Jacq.

PubMed

Celis-Arámburo, Teresita de Jesús; Carrillo-Pech, Mildred; Castro-Concha, Lizbeth A; Miranda-Ham, María de Lourdes; Martínez-Estévez, Manuel; Echevarría-Machado, Ileana

2011-12-01

The effects of nitrate (NO₃⁻) on the root system are complex and depend on several factors, such as the concentration available to the plant, endogenous nitrogen status and the sensitivity of the species. Though these effects have been widely documented on Arabidopsis and cereals, no reports are available in the Capsicum genus. In this paper, we have determined the effect of an exogenous in vitro application of this nutrient on root growth in habanero pepper (Capsicum chinense Jacq.). Exposure to NO₃⁻ inhibited primary root growth in both, dose- and time-dependent manners. The highest inhibition was attained with 0.1 mM NO₃⁻ between the fourth and fifth days of treatment. Inhibition of primary root growth was observed by exposing the root to both homogeneous and heterogeneous conditions of the nutrient; in contrast, ammonium was not able to induce similar changes. NO₃⁻-induced inhibition of primary root growth was reversed by treating the roots with IAA or NPA, a polar auxin transport inhibitor. Heterogeneous NO₃⁻ application stimulated the formation and elongation of lateral roots in the segment where the nutrient was present, and this response was influenced by exogenous phytohormones. These results demonstrate that habanero pepper responds to NO₃⁻ in a similar fashion to other species with certain particular differences. Therefore, studies in this model could help to elucidate the mechanisms by which roots respond to NO₃⁻ in fluctuating soil environments. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

A Physiological and Behavioral Mechanism for Leaf Herbivore-Induced Systemic Root Resistance1[OPEN

PubMed Central

Erb, Matthias; Robert, Christelle A.M.; Marti, Guillaume; Lu, Jing; Doyen, Gwladys R.; Villard, Neil; Barrière, Yves; Wolfender, Jean-Luc; Turlings, Ted C.J.

2015-01-01

Indirect plant-mediated interactions between herbivores are important drivers of community composition in terrestrial ecosystems. Among the most striking examples are the strong indirect interactions between spatially separated leaf- and root-feeding insects sharing a host plant. Although leaf feeders generally reduce the performance of root herbivores, little is known about the underlying systemic changes in root physiology and the associated behavioral responses of the root feeders. We investigated the consequences of maize (Zea mays) leaf infestation by Spodoptera littoralis caterpillars for the root-feeding larvae of the beetle Diabrotica virgifera virgifera, a major pest of maize. D. virgifera strongly avoided leaf-infested plants by recognizing systemic changes in soluble root components. The avoidance response occurred within 12 h and was induced by real and mimicked herbivory, but not wounding alone. Roots of leaf-infested plants showed altered patterns in soluble free and soluble conjugated phenolic acids. Biochemical inhibition and genetic manipulation of phenolic acid biosynthesis led to a complete disappearance of the avoidance response of D. virgifera. Furthermore, bioactivity-guided fractionation revealed a direct link between the avoidance response of D. virgifera and changes in soluble conjugated phenolic acids in the roots of leaf-attacked plants. Our study provides a physiological mechanism for a behavioral pattern that explains the negative effect of leaf attack on a root-feeding insect. Furthermore, it opens up the possibility to control D. virgifera in the field by genetically mimicking leaf herbivore-induced changes in root phenylpropanoid patterns. PMID:26430225

Comparing the Effect of Different Voxel Resolutions for Assessment of Vertical Root Fracture of Permanent Teeth

PubMed Central

Uzun, Ismail; Gunduz, Kaan; Celenk, Peruze; Avsever, Hakan; Orhan, Kaan; Canitezer, Gozde; Ozmen, Bilal; Cicek, Ersan; Egrioglu, Erol

2015-01-01

Background: The teeth with undiagnosed vertical root fractures (VRFs) are likely to receive endodontic treatment or retreatment, leading to frustration and inappropriate endodontic therapies. Moreover, many cases of VRFs cannot be diagnosed definitively until the extraction of tooth. Objectives: This study aimed to assess the use of different voxel resolutions of two different cone beam computerized tomography (CBCT) units in the detection VRFs in vitro. Materials and Methods: The study material comprised 74 extracted human mandibular single rooted premolar teeth without root fractures that had not undergone any root-canal treatment. Images were obtained by two different CBCT units. Four image sets were obtained as follows: 1) 3D Accuitomo 170, 4 × 4 cm field of view (FOV) (0.080 mm3); 2) 3D Accuitomo 170. 6 × 6 cm FOV (0.125 mm3); 3) NewTom 3G, 6˝ (0.16 mm3) and 4) NewTom 3G, 9˝ FOV (0.25 mm3). Kappa coefficients were calculated to assess both intra- and inter-observer agreements for each image set. Results: No significant differences were found among observers or voxel sizes, with high average Z (Az) results being reported for all groups. Both intra- and inter-observer agreement values were relatively better for 3D Accuitomo 170 images than the images from NewTom 3G. The highest Az and kappa values were obtained with 3D Accuitomo 170, 4 × 4 cm FOV (0.080 mm3) images. Conclusion: No significant differences were found among observers or voxel sizes, with high Az results reported for all groups. PMID:26557279

The effect of vertical bracket positioning on torque and the resultant stress in the periodontal ligament--a finite element study.

PubMed

Sardarian, Ahmadreza; Danaei, Shahla Momeni; Shahidi, Shoaleh; Boushehri, Sahar Ghodsi; Geramy, Allahyar

2014-01-01

The ideal built-in tip and torque values of the straight wire appliance reduce the need for wire bending and hence reduce chair time. The vertical position of the bracket on the tooth surface can alter the torque exerted on the tooth. This is a result of the altered surface curvature observed at each vertical position. To further clarify the role of vertical bracket positioning on the applied torque and the resultant stresses in the periodontal ligament (PDL), we designed a mandibular first premolar using finite element modeling. Cone beam computed tomography of 52 patients (83 lower first premolars) was selected to be included in the study. Curvature was measured for points along the labial surface with increasing distances (0.5 mm increments) from the cusp tip by calculating the angle between tangents drawn from these points and the axis joining the cusp tip and the root apex. The mean values for each distance were calculated, and a finite element model was designed incorporating these mean values. The resultant stress and hydrostatic pressure in the PDL were calculated using finite element analysis. The labial surface of the mandibular first premolar demonstrated a 26.39° change from 2.5 to 6 mm from the cusp tip. The maximum Von-Mises stress and hydrostatic pressure in the PDL were observed at the root apex for all of the bracket positions, and these values demonstrated, respectively, a change of up to 0.059 and 0.186 MPa between two successive points. It can be concluded that the variation in the vertical position of the bracket can have an important effect on the torque and subsequently on the stresses and pressures in the PDL.

Langley Full-scale-tunnel Investigation of Maximum Lift and Stability Characteristics of an Airplane Having Approximately Triangular Plan Form (DM-1 Glider)

NASA Technical Reports Server (NTRS)

Lovell, J Calvin; Wilson, Herbert A JR

1947-01-01

An investigation of the DM-1 Glider, which had approximately triangular plan form, an aspect ratio of 1.8 and a 60 degree sweptback leading edge, has been conducted in the Langley full-scale tunnel. The investigation consisted of the determination of the separate effects of the following modifications made to the glider on its maximum lift and stability characteristics: (a) installation of sharp leading edges over the inboard semispan of the wing, (b) removal of the vertical fin, (c) sealing of the elevon control-balance slots, (d) installation of redesigned thin vertical surfaces, (e) installation of faired sharp leading edges, and (f) installation of canopy. The maximum lift coefficient of the DM-1 glider was increased from 0.61 to 1.01 by the installation of semispan sharp leading edges, and from 1.01 to 1.24 by the removal of the vertical fin and sealing of the elevon control-balance slots. The highest maximum lift coefficient (1.32) was obtained when the faired sharp leading edges and the thin vertical surfaces were attached to the glider. The original DM-1 glider was longitudinally stable. The semispan sharp leading edges shifted the neutral point forward approximately 3 percent of the root chord at moderate lift coefficients, and the glider configuration with these sharp leading edges attached was longitudinally unstable, for the assumed center-of-gravity location, at lift coefficients above 0.73. Sealing the elevon control-balance slots and installing the faired sharp leading edges, the thin vertical surfaces, and the canopy shifted the neutral point forward approximately 8 percent of the root chord.

[Effects of tree species diversity on fine-root biomass and morphological characteristics in subtropical Castanopsis carlesii forests].

PubMed

Wang, Wei-Wei; Huang, Jin-Xue; Chen, Feng; Xiong, De-Cheng; Lu, Zheng-Li; Huang, Chao-Chao; Yang, Zhi-Jie; Chen, Guang-Shui

2014-02-01

Fine roots in the Castanopsis carlesii plantation forest (MZ), the secondary forest of C. carlesii through natural regeneration with anthropogenic promotion (AR), and the secondary forest of C. carlesii through natural regeneration (NR) in Sanming City, Fujian Province, were estimated by soil core method to determine the influence of tree species diversity on biomass, vertical distribution and morphological characteristics of fine roots. The results showed that fine root biomass for the 0-80 cm soil layer in the MZ, AR and NR were (182.46 +/- 10.81), (242.73 +/- 17.85) and (353.11 +/- 16.46) g x m(-2), respectively, showing an increased tendency with increasing tree species diversity. In the three forests, fine root biomass was significantly influenced by soil depth, and fine roots at the 0-10 cm soil layer accounted for more than 35% of the total fine root biomass. However, the interaction of stand type and soil depth on fine-root distribution was not significant, indicating no influence of tree species diversity on spatial niche segregation in fine roots. Root surface area density and root length density were the highest in NR and lowest in the MZ. Specific root length was in the order of AR > MZ > NR, while specific root surface area was in the order of NR > MZ > AR. There was no significant interaction of stand type and soil depth on specific root length and specific root surface area. Fine root morphological plasticity at the stand level had no significant response to tree species diversity.

Exploitation of nutrient- and C-rich paleosols by deep rooting plants in Dutch drift- and coversands

NASA Astrophysics Data System (ADS)

Gocke, Martina; Kessler, Fabian; van Mourik, Jan; Jansen, Boris; Wiesenberg, Guido L. B.

2015-04-01

Plant roots are commonly assumed to be most abundant in topsoil, with strongly decreasing frequencies in underlying soil horizons with incrasing depth and almost absence of roots below the uppermost few dm due to unfavorable environmental conditions in terms of e.g. aeration, nutrient availability or water, that hamper root growth. It still remains unknown, to which extent roots might be able to exploit deeper parts of soils and underlying soil parent material as well as burried paleosols. The study site is located in SE Netherlands. Undisturbed oak forests developed about 200 years ago on stabilized driftsand, deposited on a plaggic Anthrosol after approximately 700 years of agricultural use. The soil profile, consisting of the recent initial Podzol in driftsand, overlying 1.1 m thick plaggic deposits that were established in a 0.5 m thick residual Podzol in coversand, was excavated in a pit of 2.3 m depth. Living and dead roots were counted throughout the profile on both, the vertical wall and horizontal levels. Additionally, soil or sediment samples free of visible root remains were collected in depth intervals between 0.05 m and 0.15 m from topsoil down to the coversand. A multi-proxy approach, including assessment of bulk elemental composition of soil, sediments and paleosol and molecular structure of organic matter therein, organic carbon contents, bulk density and pH was applied in order to comprehensively describe the varying environmental conditions within the soil profile and in transects from roots to root-free material. The burried agricultural soil revealed low density and high organic carbon contents compared to the coversand parent material, and especially in its lower part, high phosphorous contents. In contrast, the burried Podzol was characterized by completely different geochemical and physical properties, like increasing pH with depth and high iron and aluminium contents. In the recent initial Podzol, fine roots (≤ 2 mm), deriving from both oak trees and understory vegetation, immediately decreased from 476 m-2 to 24 m-2, whereas medium roots (2-5 mm) from oak trees continuously increased from 8 m-2 at the surface to 188 m-2 within the upper part of the agricultural soil. Both, frequencies of fine and medium roots peaked at 4.448 m-2 and 216 m-2, respectively, in the uppermost part of the burried Podzol, thus considerably exceeding topsoil abundances. Comparison of these results with those obtained at the profile wall demonstrated that fine root abundances might be considerably underestimated by the more traditional approach of profile wall investigation, because fine roots were growing vertically to exploit the nutrient-rich burried paleosols. Unlike fine roots, medium roots and even more, large roots (> 5 mm) were not able to penetrate the hard sesquioxide crusts of the burried Podzol in larger numbers. Our results show that roots are able to deeply penetrate the soil and underlying soil parent material or paleosols, if the latter provides nutrition benefits. Root distribution strongly depends on physical and chemical properties of the deep subsoil, which should be taken into account when interpreting complex soil profiles covering recent and paleosols.

Chemical Characterization, Free Radical Scavenging, and Cellular Antioxidant and Anti-Inflammatory Properties of a Stilbenoid-Rich Root Extract of Vitis vinifera

PubMed Central

Esatbeyoglu, Tuba; Ewald, Philipp; Yasui, Yoshiaki; Yokokawa, Haruka; Wagner, Anika E.; Matsugo, Seiichi; Winterhalter, Peter; Rimbach, Gerald

2016-01-01

Dietary stilbenoids are receiving increasing attention due to their potential health benefits. However, most studies concerning the bioactivity of stilbenoids were conducted with pure compounds, for example, resveratrol. The aim of this study was to characterize a complex root extract of Vitis vinifera in terms of its free radical scavenging and cellular antioxidant and anti-inflammatory properties. HPLC-ESI-MS/MS analyses of the root extract of Vitis vinifera identified seven stilbenoids including two monomeric (resveratrol and piceatannol), two dimeric (trans-ɛ-viniferin and ampelopsin A), one trimeric (miyabenol C), and two tetrameric (r-2-viniferin = vitisin A and r-viniferin = vitisin B) compounds which may mediate its biological activity. Electron spin resonance and spin trapping experiments indicate that the root extract scavenged 2,2-diphenyl-1-picrylhydrazyl, hydroxyl, galvinoxyl, and superoxide free radicals. On a cellular level it was observed that the root extract of Vitis vinifera protects against hydrogen peroxide-induced DNA damage and induces Nrf2 and its target genes heme oxygenase-1 and γ-glutamylcysteine synthetase. Furthermore, the root extract could induce the antiatherogenic hepatic enzyme paraoxonase 1 and downregulate proinflammatory gene expression (interleukin 1β, inducible nitric oxide synthase) in macrophages. Collectively our data suggest that the root extract of Vitis vinifera exhibits free radical scavenging as well as cellular antioxidant and anti-inflammatory properties. PMID:26788254

Shifting from priming of salicylic acid- to jasmonic acid-regulated defences by Trichoderma protects tomato against the root knot nematode Meloidogyne incognita.

PubMed

Martínez-Medina, Ainhoa; Fernandez, Ivan; Lok, Gerrit B; Pozo, María J; Pieterse, Corné M J; Van Wees, Saskia C M

2017-02-01

Beneficial root endophytes such as Trichoderma spp. can reduce infections by parasitic nematodes through triggering host defences. Little is currently known about the complex hormone signalling underlying the induction of resistance. In this study, we investigated whether Trichoderma modulates the hormone signalling network in the host to induce resistance to nematodes. We investigated the role and the timing of the jasmonic acid (JA)- and salicylic acid (SA)-regulated defensive pathways in Trichoderma-induced resistance to the root knot nematode Meloidogyne incognita. A split-root system of tomato (Solanum lycopersicum) was used to study local and systemic induced defences by analysing nematode performance, defence gene expression, responsiveness to exogenous hormone application, and dependence on SA and JA signalling of Trichoderma-induced resistance. Root colonization by Trichoderma impeded nematode performance both locally and systemically at multiple stages of the parasitism, that is, invasion, galling and reproduction. First, Trichoderma primed SA-regulated defences, which limited nematode root invasion. Then, Trichoderma enhanced JA-regulated defences, thereby antagonizing the deregulation of JA-dependent immunity by the nematodes, which compromised galling and fecundity. Our results show that Trichoderma primes SA- and JA-dependent defences in roots, and that the priming of responsiveness to these hormones upon nematode attack is plastic and adaptive to the parasitism stage. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

Microstructures, composition, and seismic properties of the Ontong Java Plateau mantle root

NASA Astrophysics Data System (ADS)

Tommasi, Andréa.; Ishikawa, Akira

2014-11-01

To study how an impacting plume modifies the mantle lithosphere, we analyzed the microstructures and crystal preferred orientations (CPO) of 29 peridotites and 37 pyroxenites that sample the mantle root of the Ontong Java Plateau (OJP) from 60 to 120 km depth. The peridotites show a strong compositional variability, but homogeneous coarse granular to tabular microstructures, except for those equilibrated at the shallowest and deepest depths, which are porphyroclastic. All peridotites have clear olivine CPO, with dominant fiber-[010] patterns. Low intragranular misorientations and straight grain boundaries in olivine suggest that, above 100 km depth, annealing often followed deformation. Calculated density and P wave velocities of the peridotites decrease weakly with depth. S wave velocities decrease faster, resulting in increasing Vp/Vs ratio with depth. Calculated densities and seismic velocity profiles are consistent with those estimated for normal mantle compositions under a cold oceanic geotherm. Enrichment in pyroxenites may further increase seismic velocities. The calculated seismic properties cannot therefore explain the low S waves velocities predicted by Rayleigh wave tomography and ScS data in the mantle beneath the OJP. Calculated P and S waves anisotropy is variable (2-12%). It is higher on average in the deeper section of the lithosphere. Because olivine has dominantly [010]-fiber CPO patterns, if foliations are horizontal, vertically propagating S waves and Rayleigh waves will sample very weak anisotropy in the OJP mantle lithosphere. Moreover, if the orientation of the lineation changes with depth, the anisotropy-induced contrast in seismic properties might produce an intralithospheric reflector marking the stratification of the OJP mantle root.

Potential involvement of drought-induced Ran GTPase CLRan1 in root growth enhancement in a xerophyte wild watermelon.

PubMed

Akashi, Kinya; Yoshimura, Kazuya; Kajikawa, Masataka; Hanada, Kouhei; Kosaka, Rina; Kato, Atsushi; Katoh, Akira; Nanasato, Yoshihiko; Tsujimoto, Hisashi; Yokota, Akiho

2016-10-01

Enhanced root growth is known as the survival strategy of plants under drought. Previous proteome analysis in drought-resistant wild watermelon has shown that Ran GTPase, an essential regulator of cell division and proliferation, was induced in the roots under drought. In this study, two cDNAs were isolated from wild watermelon, CLRan1 and CLRan2, which showed a high degree of structural similarity with those of other plant Ran GTPases. Quantitative RT-PCR and promoter-GUS assays suggested that CLRan1 was expressed mainly in the root apex and lateral root primordia, whereas CLRan2 was more broadly expressed in other part of the roots. Immunoblotting analysis confirmed that the abundance of CLRan proteins was elevated in the root apex region under drought stress. Transgenic Arabidopsis overexpressing CLRan1 showed enhanced primary root growth, and the growth was maintained under osmotic stress, indicating that CLRan1 functions as a positive factor for maintaining root growth under stress conditions.

Flavonols Mediate Root Phototropism and Growth through Regulation of Proliferation-to-Differentiation Transition.

PubMed

Silva-Navas, Javier; Moreno-Risueno, Miguel A; Manzano, Concepción; Téllez-Robledo, Bárbara; Navarro-Neila, Sara; Carrasco, Víctor; Pollmann, Stephan; Gallego, F Javier; Del Pozo, Juan C

2016-06-01

Roots normally grow in darkness, but they may be exposed to light. After perceiving light, roots bend to escape from light (root light avoidance) and reduce their growth. How root light avoidance responses are regulated is not well understood. Here, we show that illumination induces the accumulation of flavonols in Arabidopsis thaliana roots. During root illumination, flavonols rapidly accumulate at the side closer to light in the transition zone. This accumulation promotes asymmetrical cell elongation and causes differential growth between the two sides, leading to root bending. Furthermore, roots illuminated for a long period of time accumulate high levels of flavonols. This high flavonol content decreases both auxin signaling and PLETHORA gradient as well as superoxide radical content, resulting in reduction of cell proliferation. In addition, cytokinin and hydrogen peroxide, which promote root differentiation, induce flavonol accumulation in the root transition zone. As an outcome of prolonged light exposure and flavonol accumulation, root growth is reduced and a different root developmental zonation is established. Finally, we observed that these differentiation-related pathways are required for root light avoidance. We propose that flavonols function as positional signals, integrating hormonal and reactive oxygen species pathways to regulate root growth direction and rate in response to light. © 2016 American Society of Plant Biologists. All rights reserved.

Flavonols Mediate Root Phototropism and Growth through Regulation of Proliferation-to-Differentiation Transition

PubMed Central

Silva-Navas, Javier; Moreno-Risueno, Miguel A.; Manzano, Concepción; Téllez-Robledo, Bárbara; Navarro-Neila, Sara; Carrasco, Víctor; Pollmann, Stephan

2016-01-01

Roots normally grow in darkness, but they may be exposed to light. After perceiving light, roots bend to escape from light (root light avoidance) and reduce their growth. How root light avoidance responses are regulated is not well understood. Here, we show that illumination induces the accumulation of flavonols in Arabidopsis thaliana roots. During root illumination, flavonols rapidly accumulate at the side closer to light in the transition zone. This accumulation promotes asymmetrical cell elongation and causes differential growth between the two sides, leading to root bending. Furthermore, roots illuminated for a long period of time accumulate high levels of flavonols. This high flavonol content decreases both auxin signaling and PLETHORA gradient as well as superoxide radical content, resulting in reduction of cell proliferation. In addition, cytokinin and hydrogen peroxide, which promote root differentiation, induce flavonol accumulation in the root transition zone. As an outcome of prolonged light exposure and flavonol accumulation, root growth is reduced and a different root developmental zonation is established. Finally, we observed that these differentiation-related pathways are required for root light avoidance. We propose that flavonols function as positional signals, integrating hormonal and reactive oxygen species pathways to regulate root growth direction and rate in response to light. PMID:26628743

Genetic elicitation by inducible expression of β-cryptogein stimulates secretion of phenolics from Coleus blumei hairy roots.

PubMed

Vuković, Rosemary; Bauer, Nataša; Curković-Perica, Mirna

2013-02-01

The accumulation of phenolic compounds in plants is often part of the defense response against stress and pathogen attack, which can be triggered and activated by elicitors. Oomycetal proteinaceous elicitor, β-cryptogein, induces hypersensitive response and systemic acquired resistance against some pathogens. In order to test the effect of endogenously synthesized cryptogein protein on phenolic compounds accumulation in tissue, and secretion into the culture medium, Coleus blumei hairy roots were generated. Agrobacterium rhizogenes was employed to insert synthetic crypt gene, encoding β-cryptogein, under the control of alcohol-inducible promoter. The expression of β-cryptogein, in C. blumei hairy roots, was controlled by application of 1% and 2% ethanol, during 21 days induction period. Ethanol-induced expression of β-cryptogein caused significant decrease of soluble phenolics and rosmarinic acid (RA) in hairy root lines and increase of phenolics, RA and caffeic acid in culture medium. These data suggest that β-cryptogein might be a potential regulatory factor for phenolics secretion from the roots. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Microcystin-LR-induced phytotoxicity in rice crown root is associated with the cross-talk between auxin and nitric oxide.

PubMed

Chen, Jian; Zhang, Hai-Qiang; Hu, Liang-Bin; Shi, Zhi-Qi

2013-09-01

Irrigation with cyanobacterial-blooming water containing microcystin-LR (MC-LR) poses threat to the growth of agricultural plants. Large amounts of rice (Oryza sativa) field in the middle part of China has been irrigating with cyanobacterial-blooming water. Nevertheless, the mechanism of MC-LR-induced phytotoxicity in the root of monocot rice remains unclear. In the present study, we demonstrate that MC-LR stress significantly inhibits the growth of rice root by impacting the morphogenesis rice crown root. MC-LR treatment results in the decrease in IAA (indole-3-acetic acid) concentration as well as the expression of CRL1 and WOX11 in rice roots. The application of NAA (1-naphthylacetic acid), an IAA homologue, is able to attenuate the inhibitory effect of MC-LR on rice root development. MC-LR treatment significantly inhibits OsNia1-dependent NO generation in rice roots. The application of NO donor SNP (sodium nitroprusside) is able to partially reverse the inhibitory effects of MC-LR on the growth of rice root and the expression of CRL1 and WOX11 by enhancing endogenous NO level in rice roots. The application of NO scavenger cPTIO [2-(4-carboxy-2-phenyl)-4,4,5,5-tetramethylinidazoline-1-oxyl-3-oxide] eliminates the effects of SNP. Treatment with NAA stimulates the generation of endogenous NO in MC-LR-treated rice roots. Treatment with NO scavenger cPTIO abolishes the ameliorated effect of NAA on MC-LR-induced growth inhibition of rice root. Treatment with SNP enhanced IAA concentration in MC-LR-treated rice roots. Altogether, our data suggest that NO acts both downstream and upstream of auxin in regulating rice root morphogenesis under MC-LR stress. Copyright © 2013 Elsevier Ltd. All rights reserved.

Characterization of low phosphorus insensitive Mutants Reveals a Crosstalk between Low Phosphorus-Induced Determinate Root Development and the Activation of Genes Involved in the Adaptation of Arabidopsis to Phosphorus Deficiency1

PubMed Central

Sánchez-Calderón, Lenin; López-Bucio, José; Chacón-López, Alejandra; Gutiérrez-Ortega, Abel; Hernández-Abreu, Esmeralda; Herrera-Estrella, Luis

2006-01-01

Low phosphorus (P) availability is one of the most limiting factors for plant productivity in many natural and agricultural ecosystems. Plants display a wide range of adaptive responses to cope with low P stress, which generally serve to enhance P availability in the soil and to increase its uptake by roots. In Arabidopsis (Arabidopsis thaliana), primary root growth inhibition and increased lateral root formation have been reported to occur in response to P limitation. To gain knowledge of the genetic mechanisms that regulate root architectural responses to P availability, we designed a screen for identifying Arabidopsis mutants that fail to arrest primary root growth when grown under low P conditions. Eleven low phosphorus insensitive (lpi) mutants that define at least four different complementation groups involved in primary root growth responses to P availability were identified. The lpi mutants do not show the typical determinate developmental program induced by P stress in the primary root. Other root developmental aspects of the low P rescue system, including increased root hair elongation and anthocyanin accumulation, remained unaltered in lpi mutants. In addition to the insensitivity of primary root growth inhibition, when subjected to P deprivation, lpi mutants show a reduced induction in the expression of several genes involved in the P starvation rescue system (PHOSPHATE TRANSPORTER 1 and 2, PURPLE ACID PHOSPHATASE 1, ACID PHOSPHATASE 5, and INDUCED BY PHOSPHATE STARVATION 1). Our results provide genetic support for the role of P as an important signal for postembryonic root development and root meristem maintenance and show a crosstalk in developmental and biochemical responses to P deprivation. PMID:16443695

Posterior Root Meniscal Tears: Preoperative, Intraoperative, and Postoperative Imaging for Transtibial Pullout Repair.

PubMed

Palisch, Andrew R; Winters, Ronald R; Willis, Marc H; Bray, Collin D; Shybut, Theodore B

2016-10-01

The menisci play an important biomechanical role in axial load distribution of the knees by means of hoop strength, which is contingent on intact circumferentially oriented collagen fibers and meniscal root attachments. Disruption of the meniscal root attachments leads to altered biomechanics, resulting in progressive cartilage loss, osteoarthritis, and subchondral edema, with the potential for development of a subchondral insufficiency fracture. Identification of meniscal root tears at magnetic resonance (MR) imaging is crucial because new arthroscopic surgical techniques (transtibial pullout repair) have been developed to repair meniscal root tears and preserve the tibiofemoral cartilage of the knee. An MR imaging classification of posterior medial meniscal root ligament lesions has been recently described that is dedicated to the posterior root of the medial meniscus. An arthroscopic classification of meniscal root tears has been described that can be applied to the anterior and posterior roots of both the medial meniscus and the lateral meniscus. This arthroscopic classification includes type 1, partial stable root tears; type 2, complete radial root tears; type 3, vertical longitudinal bucket-handle tears; type 4, complex oblique tears; and type 5, bone avulsion fractures of the root attachments. Knowledge of these classifications and the potential contraindications to meniscal root repair can aid the radiologist in the preoperative reporting of meniscal root tear types and the evaluation of the tibiofemoral cartilage. As more patients undergo arthroscopic repair of meniscal root tears, familiarity with the surgical technique and the postoperative radiographic and MR imaging appearance is important to adequately report the imaging findings. © RSNA, 2016.

Ethylene and nitric oxide interact to regulate the magnesium deficiency-induced root hair development in Arabidopsis.

PubMed

Liu, Miao; Liu, Xing Xing; He, Xiao Lin; Liu, Li Juan; Wu, Hao; Tang, Cai Xian; Zhang, Yong Song; Jin, Chong Wei

2017-02-01

Nitric oxide (NO) and ethylene respond to biotic and abiotic stresses through either similar or independent processes. This study examines the mechanism underlying the effects of NO and ethylene on promoting root hair development in Arabidopsis under magnesium (Mg) deficiency. The interaction between NO and ethylene in the regulation of Mg deficiency-induced root hair development was investigated using NO- and ethylene-related mutants and pharmacological methods. Mg deficiency triggered a burst of NO and ethylene, accompanied by a stimulated development of root hairs. Interestingly, ethylene facilitated NO generation by activation of both nitrate reductase and nitric oxide synthase-like (NOS-L) in the roots of Mg-deficient plants. In turn, NO enhanced ethylene synthesis through stimulating the activities of 1-aminocyclopropane-1-carboxylate (ACC) oxidase and ACC synthase (ACS). These two processes constituted an NO-ethylene feedback loop. Blocking either of these two processes inhibited the stimulation of root hair development under Mg deficiency. In conclusion, we suggest that Mg deficiency increases the production of NO and ethylene in roots, each influencing the accumulation and role of the other, and thus these two signals interactively regulate Mg deficiency-induced root hair morphogenesis. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

Root development of winter wheat in erosion-affected soils depending on the position in a hummocky ground moraine soil landscape

NASA Astrophysics Data System (ADS)

Herbrich, Marcus; Gerke, Horst H.; Sommer, Michael

2017-04-01

The soil water uptake by crops is a key process in the hydrological cycle of agricultural ecosystems. In the arable hummocky ground moraines soil landscapes, an erosion-induced spatial differentiation of soil types has been established due to water and tillage erosion. Crop development may reflect soil landscape patterns and erosion-induced soil profile modifications, respectively, by increased or reduced plant and root growth. The objective was analyze field data of the root density and the root lengths of winter wheat for a non-eroded reference soil at the plateau (Albic Luvisol), an extremely eroded soil at steep midslope (Calcaric Regosol), and depositional soil at the footslope (Colluvic Regosol) using the minirhizotron technique. From 9/14 to 8/15 results indicate that root density values were highest for the Colluvic Regosol, followed by the Albic Luvisol and lowest for the Calcaric Regosol. In turn, the lowest maximum root penetration depth was found in the Colluvic Regosol because of the relatively high and fluctuating water table at this landscape position. The analyzed field root data revealed positive relations to above-ground plant parameters and corroborated the hypothesis that the crop root system was reflecting erosion-induced soil profile modifications. When accounting for the position-specific root development, the simulation of water and solute movement suggested differences in the balances as compared to assuming a spatially uniform development.

The Basic Helix-Loop-Helix Transcription Factor MYC2 Directly Represses PLETHORA Expression during Jasmonate-Mediated Modulation of the Root Stem Cell Niche in Arabidopsis[W][OA

PubMed Central

Chen, Qian; Sun, Jiaqiang; Zhai, Qingzhe; Zhou, Wenkun; Qi, Linlin; Xu, Li; Wang, Bao; Chen, Rong; Jiang, Hongling; Qi, Jing; Li, Xugang; Palme, Klaus; Li, Chuanyou

2011-01-01

The root stem cell niche, which in the Arabidopsis thaliana root meristem is an area of four mitotically inactive quiescent cells (QCs) and the surrounding mitotically active stem cells, is critical for root development and growth. We report here that during jasmonate-induced inhibition of primary root growth, jasmonate reduces root meristem activity and leads to irregular QC division and columella stem cell differentiation. Consistently, jasmonate reduces the expression levels of the AP2-domain transcription factors PLETHORA1 (PLT1) and PLT2, which form a developmentally instructive protein gradient and mediate auxin-induced regulation of stem cell niche maintenance. Not surprisingly, the effects of jasmonate on root stem cell niche maintenance and PLT expression require the functioning of MYC2/JASMONATE INSENSITIVE1, a basic helix-loop-helix transcription factor that involves versatile aspects of jasmonate-regulated gene expression. Gel shift and chromatin immunoprecipitation experiments reveal that MYC2 directly binds the promoters of PLT1 and PLT2 and represses their expression. We propose that MYC2-mediated repression of PLT expression integrates jasmonate action into the auxin pathway in regulating root meristem activity and stem cell niche maintenance. This study illustrates a molecular framework for jasmonate-induced inhibition of root growth through interaction with the growth regulator auxin. PMID:21954460

Plants as green phones

PubMed Central

Harvey, Jeffrey A; Bezemer, T Martijn; Stuefer, Josef F

2008-01-01

Plants can act as vertical communication channels or ‘green phones’ linking soil-dwelling insects and insects in the aboveground ecosystem. When root-feeding insects attack a plant, the direct defense system of the shoot is activated, leading to an accumulation of phytotoxins in the leaves. The protection of the plant shoot elicited by root damage can impair the survival, growth and development of aboveground insect herbivores, thereby creating plant-based functional links between soil-dwelling insects and insects that develop in the aboveground ecosystem. The interactions between spatially separated insects below- and aboveground are not restricted to root and foliar plant-feeding insects, but can be extended to higher trophic levels such as insect parasitoids. Here we discuss some implications of plants acting as communication channels or ‘green phones’ between root and foliar-feeding insects and their parasitoids, focusing on recent findings that plants attacked by root-feeding insects are significantly less attractive for the parasitoids of foliar-feeding insects. PMID:19513244

Plants as green phones: Novel insights into plant-mediated communication between below- and above-ground insects.

PubMed

Soler, Roxina; Harvey, Jeffrey A; Bezemer, T Martijn; Stuefer, Josef F

2008-08-01

Plants can act as vertical communication channels or 'green phones' linking soil-dwelling insects and insects in the aboveground ecosystem. When root-feeding insects attack a plant, the direct defense system of the shoot is activated, leading to an accumulation of phytotoxins in the leaves. The protection of the plant shoot elicited by root damage can impair the survival, growth and development of aboveground insect herbivores, thereby creating plant-based functional links between soil-dwelling insects and insects that develop in the aboveground ecosystem. The interactions between spatially separated insects below- and aboveground are not restricted to root and foliar plant-feeding insects, but can be extended to higher trophic levels such as insect parasitoids. Here we discuss some implications of plants acting as communication channels or 'green phones' between root and foliar-feeding insects and their parasitoids, focusing on recent findings that plants attacked by root-feeding insects are significantly less attractive for the parasitoids of foliar-feeding insects.

Nitric oxide is involved in hydrogen gas-induced cell cycle activation during adventitious root formation in cucumber.

PubMed

Zhu, Yongchao; Liao, Weibiao; Niu, Lijuan; Wang, Meng; Ma, Zhanjun

2016-06-28

Adventitious root development is a complex process regulated through a variety of signaling molecules. Hydrogen gas (H2) and nitric oxide (NO), two new signaling molecules are both involved in plant development and stress tolerance. To investigate the mechanism of adventitious root development induced by hydrogen-rich water (HRW), a combination of fluorescence microscopy and molecular approaches was used to study cell cycle activation and cell cycle-related gene expression in cucumber (Cucumis sativus 'Xinchun 4') explants. The results revealed that the effect of HRW on adventitious root development was dose-dependent, with maximal biological responses at 50 % HRW. HRW treatment increased NO content in a time-dependent fashion. The results also indicated that HRW and NO promoted the G1-to-S transition and up-regulated cell cycle-related genes: CycA (A-type cyclin), CycB (B-type cyclin), CDKA (cyclin-dependent kinase A) and CDKB (cyclin-dependent kinase B) expression. Additionally, target genes related to adventitious rooting were up-regulated by HRW and NO in cucumber explants. While, the responses of HRW-induced adventitious root development and increase of NO content were partially blocked by a specific NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide potassium salt, NO synthase (NOS)-like enzyme inhibitor N(G) -nitro-L-arginine methylester hydrochloride, or nitrate reductase inhibitors tungstate and NaN3. These chemicals also partially reversed the effect of HRW on cell cycle activation and the transcripts of cell cycle regulatory genes and target genes related adventitious root formation. Together, NO may emerge as a downstream signaling molecule in H2-induced adventitious root organogenesis. Additionally, H2 mediated cell cycle activation via NO pathway during adventitious root formation.

A new three-locus model for rootstock-induced dwarfing in apple revealed by genetic mapping of root bark percentage

PubMed Central

Harrison, Nicola; Harrison, Richard J.; Barber-Perez, Nuria; Cascant-Lopez, Emma; Cobo-Medina, Magdalena; Lipska, Marzena; Conde-Ruíz, Rebeca; Brain, Philip; Gregory, Peter J.; Fernández-Fernández, Felicidad

2016-01-01

Rootstock-induced dwarfing of apple scions revolutionized global apple production during the twentieth century, leading to the development of modern intensive orchards. A high root bark percentage (the percentage of the whole root area constituted by root cortex) has previously been associated with rootstock-induced dwarfing in apple. In this study, the root bark percentage was measured in a full-sib family of ungrafted apple rootstocks and found to be under the control of three loci. Two quantitative trait loci (QTLs) for root bark percentage were found to co-localize to the same genomic regions on chromosome 5 and chromosome 11 previously identified as controlling dwarfing, Dw1 and Dw2, respectively. A third QTL was identified on chromosome 13 in a region that has not been previously associated with dwarfing. The development of closely linked sequence-tagged site markers improved the resolution of allelic classes, thereby allowing the detection of dominance and epistatic interactions between loci, with high root bark percentage only occurring in specific allelic combinations. In addition, we report a significant negative correlation between root bark percentage and stem diameter (an indicator of tree vigour), measured on a clonally propagated grafted subset of the mapping population. The demonstrated link between root bark percentage and rootstock-induced dwarfing of the scion leads us to propose a three-locus model that is able to explain levels of dwarfing from the dwarf ‘M.27’ to the semi-invigorating rootstock ‘M.116’. Moreover, we suggest that the QTL on chromosome 13 (Rb3) might be analogous to a third dwarfing QTL, Dw3, which has not previously been identified. PMID:26826217

The effect of iron plaque on uptake and translocation of norfloxacin in rice seedlings grown in paddy soil.

PubMed

Yan, Dafang; Ma, Wei; Song, Xiaojing; Bao, Yanyu

2017-03-01

Although the role of iron plaque on rice root surface has been investigated in recent years, its effect on antibiotic uptake remains uncertain. In the study, pot experiment was conducted to investigate the effect of iron plaque on uptake and translocation of norfloxacin (adding 10 and 50 mg·kg -1 treatments) in rice seedlings grown in paddy soil. Iron plaque was induced by adding different amounts of Fe(II) in soil. The results showed that the presence of norfloxacin can decrease the amount of iron plaque induced. After rice with iron plaque induced, norfloxacin was mainly accumulated in iron plaque on root surface, followed by inside root, but its translocation from root to other rice tissues is not observed. Iron plaque played the role of a barrier for norfloxacin uptake into rice roots under high norfloxacin concentration of 50 mg·kg -1 , however not that under low concentration of 10 mg·kg -1 . And the barrier function was the most strongest with adding Fe(II) of 30 mg·kg -1 as combined action of iron plaque and rhizosphere effect. Fluorescence microscope analysis showed that norfloxacin mainly distributed in the outside of root cell, which showed its translocation as apoplastic pathway in rice. Comparing with non-rhizosphere, more norfloxacin was accumulated in rhizosphere soil. Maybe, strong root oxidization (high Eh values) induced more iron oxide formation in rhizosphere and on root surface, which led to norfloxacin's mobility towards to rhizosphere through its strong adsorption of iron oxides and then promoted its uptake by rice on root surface.

S-nitrosoglutathione promotes cell wall remodelling, alters the transcriptional profile and induces root hair formation in the hairless root hair defective 6 (rhd6) mutant of Arabidopsis thaliana.

PubMed

Moro, Camila Fernandes; Gaspar, Marilia; da Silva, Felipe Rodrigues; Pattathil, Sivakumar; Hahn, Michael G; Salgado, Ione; Braga, Marcia Regina

2017-03-01

Nitric oxide (NO) exerts pleiotropic effects on plant development; however, its involvement in cell wall modification during root hair formation (RHF) has not yet been addressed. Here, mutants of Arabidopsis thaliana with altered root hair phenotypes were used to assess the involvement of S-nitrosoglutathione (GSNO), the primary NO source, in cell wall dynamics and gene expression in roots induced to form hairs. GSNO and auxin restored the root hair phenotype of the hairless root hair defective 6 (rhd6) mutant. A positive correlation was observed between increased NO production and RHF induced by auxin in rhd6 and transparent testa glabra (ttg) mutants. Deposition of an epitope within rhamnogalacturonan-I recognized by the CCRC-M2 antibody was delayed in root hair cells (trichoblasts) compared with nonhair cells (atrichoblasts). GSNO, but not auxin, restored the wild-type root glycome and transcriptome profiles in rhd6, modulating the expression of a large number of genes related to cell wall composition and metabolism, as well as those encoding ribosomal proteins, DNA and histone-modifying enzymes and proteins involved in post-translational modification. Our results demonstrate that NO plays a key role in cell wall remodelling in trichoblasts and suggest that it also participates in chromatin modification in root cells of A. thaliana. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

Ethylene Mediates Alkaline-Induced Rice Growth Inhibition by Negatively Regulating Plasma Membrane H+-ATPase Activity in Roots

PubMed Central

Chen, Haifei; Zhang, Quan; Cai, Hongmei; Xu, Fangsen

2017-01-01

pH is an important factor regulating plant growth. Here, we found that rice was better adapted to low pH than alkaline conditions, as its growth was severely inhibited at high pH, with shorter root length and an extreme biomass reduction. Under alkaline stress, the expression of genes for ethylene biosynthesis enzymes in rice roots was strongly induced by high pH and exogenous ethylene precursor ACC and ethylene overproduction in etol1-1 mutant aggravated the alkaline stress-mediated inhibition of rice growth, especially for the root elongation with decreased cell length in root apical regions. Conversely, the ethylene perception antagonist silver (Ag+) and ein2-1 mutants could partly alleviate the alkaline-induced root elongation inhibition. The H+-ATPase activity was extremely inhibited by alkaline stress and exogenous ACC. However, the H+-ATPase-mediated rhizosphere acidification was enhanced by exogenous Ag+, while H+ efflux on the root surface was extremely inhibited by exogenous ACC, suggesting that ethylene negatively regulated H+-ATPase activity under high-pH stress. Our results demonstrate that H+-ATPase is involved in ethylene-mediated inhibition of rice growth under alkaline stress. PMID:29114258

Selecting Populus with different adventitious root types for environmental benefits, fiber, and energy

Treesearch

Ronald S., Jr. Zalesny; Jill A. Zalesny

2009-01-01

Primary roots from seeds, sucker roots in aspens, and adventitious roots (ARs) in poplars and their hybrids are prevalent within the genus Populus. Two AR types develop on hardwood cuttings: (i) lateral roots from either preformed or induced primordia along the length of the cutting and (ii) basal roots from callus at the base of the cutting in...

Plastid sedimentation kinetics in roots of wild-type and starch-deficient mutants of Arabidopsis

NASA Technical Reports Server (NTRS)

MacCleery, S. A.; Kiss, J. Z.

1999-01-01

Sedimentation and movement of plastids in columella cells of the root cap were measured in seedlings of wild-type, a reduced starch mutant, and a starchless mutant of Arabidopsis. To assay for sedimentation, we used both linear measurements and the change of angle from the cell center as indices in vertical and reoriented plants with the aid of computer-assisted image analysis. Seedlings were fixed at short periods after reorientation, and plastid sedimentation correlated with starch content in the three strains of Arabidopsis. Amyloplasts of wild-type seedlings showed the greatest sedimentation, whereas plastids of the starchless mutant showed no significant sedimentation in the vertically grown and reoriented seedlings. Because previous research has shown that a full complement of starch is needed for full gravitropic sensitivity, this study correlates increased sensitivity with plastid sedimentation. However, although plastid sedimentation contributed to gravisensitivity, it was not required, because the gravitropic starchless mutant had plastids that did not sediment. This is the first study, to our knowledge, to measure plastid sedimentation in Arabidopsis roots after reorientation of seedlings. Taken together, the results of this study are consistent with the classic plastid-based and protoplast-based models of graviperception and suggest that multiple systems of perception exist in plant cells.

Vertical Corner Feature Based Precise Vehicle Localization Using 3D LIDAR in Urban Area

PubMed Central

Im, Jun-Hyuck; Im, Sung-Hyuck; Jee, Gyu-In

2016-01-01

Tall buildings are concentrated in urban areas. The outer walls of buildings are vertically erected to the ground and almost flat. Therefore, the vertical corners that meet the vertical planes are present everywhere in urban areas. These corners act as convenient landmarks, which can be extracted by using the light detection and ranging (LIDAR) sensor. A vertical corner feature based precise vehicle localization method is proposed in this paper and implemented using 3D LIDAR (Velodyne HDL-32E). The vehicle motion is predicted by accumulating the pose increment output from the iterative closest point (ICP) algorithm based on the geometric relations between the scan data of the 3D LIDAR. The vertical corner is extracted using the proposed corner extraction method. The vehicle position is then corrected by matching the prebuilt corner map with the extracted corner. The experiment was carried out in the Gangnam area of Seoul, South Korea. In the experimental results, the maximum horizontal position error is about 0.46 m and the 2D Root Mean Square (RMS) horizontal error is about 0.138 m. PMID:27517936

Decreasing methylation of pectin caused by nitric oxide leads to higher aluminium binding in cell walls and greater aluminium sensitivity of wheat roots

PubMed Central

Sun, Chengliang; Lu, Lingli; Yu, Yan; Liu, Lijuan; Hu, Yan; Ye, Yiquan; Jin, Chongwei; Lin, Xianyong

2016-01-01

Nitric oxide (NO) is an important bioactive molecule involved in cell wall metabolism, which has been recognized as a major target of aluminium (Al) toxicity. We have investigated the effects of Al-induced NO production on cell wall composition and the subsequent Al-binding capacity in roots of an Al-sensitive cultivar of wheat (Triticum aestivum L. cv. Yang-5). We found that Al exposure induced NO accumulation in the root tips. Eliminating NO production with an NO scavenger (cPTIO) significantly alleviated the Al-induced inhibition of root growth and thus reduced Al accumulation. Elimination of NO, however, did not significantly affect malate efflux or rhizosphere pH changes under Al exposure. Levels of cell wall polysaccharides (pectin, hemicelluloses 1, and hemicelluloses 2) and pectin methylesterase activity, as well as pectin demethylation in the root apex, significantly increased under Al treatment. Exogenous cPTIO application significantly decreased pectin methylesterase activity and increased the degree of methylation of pectin in the root cell wall, thus decreasing the Al-binding capacity of pectin. These results suggest that the Al-induced enhanced production of NO decreases cell wall pectin methylation, thus increasing the Al-binding capacity of pectin and negatively regulating Al tolerance in wheat. PMID:26663393

Rooting depth varies differentially in trees and grasses as a function of mean annual rainfall in an African savanna.

PubMed

Holdo, Ricardo M; Nippert, Jesse B; Mack, Michelle C

2018-01-01

A significant fraction of the terrestrial biosphere comprises biomes containing tree-grass mixtures. Forecasting vegetation dynamics in these environments requires a thorough understanding of how trees and grasses use and compete for key belowground resources. There is disagreement about the extent to which tree-grass vertical root separation occurs in these ecosystems, how this overlap varies across large-scale environmental gradients, and what these rooting differences imply for water resource availability and tree-grass competition and coexistence. To assess the extent of tree-grass rooting overlap and how tree and grass rooting patterns vary across resource gradients, we examined landscape-level patterns of tree and grass functional rooting depth along a mean annual precipitation (MAP) gradient extending from ~ 450 to ~ 750 mm year -1 in Kruger National Park, South Africa. We used stable isotopes from soil and stem water to make inferences about relative differences in rooting depth between these two functional groups. We found clear differences in rooting depth between grasses and trees across the MAP gradient, with grasses generally exhibiting shallower rooting profiles than trees. We also found that trees tended to become more shallow-rooted as a function of MAP, to the point that trees and grasses largely overlapped in terms of rooting depth at the wettest sites. Our results reconcile previously conflicting evidence for rooting overlap in this system, and have important implications for understanding tree-grass dynamics under altered precipitation scenarios.

Deviations of Mesial Root Canals of Mandibular First Molar Teeth at the Apical Third: A Micro-computed Tomographic Study.

PubMed

Keles, Ali; Keskin, Cangül

2018-06-01

The present study aimed to quantitatively analyze apical foramen deviations of mesial root canals of mandibular first molar teeth by means of micro-computed tomographic (micro-CT) imaging. Micro-CT images of the mesial roots of 109 mandibular first molar teeth with independent mesiobuccal (MB) and mesiolingual (ML) root canals were analyzed. The deviations of the apical foramina of the MB, ML, and middle mesial root canals from the anatomic apex were measured. The vertical distance between the apical foramina of each mesial root canal in relation to each other was also calculated. The distances from the apical foramina of the MB, ML, and middle mesial root canals to the anatomic apex of the mesial root were up to 2.51 mm, 3.21 mm, and 5.67 mm, respectively. There was no significant difference between the deviations of MB and ML root canals from each other (P > .05). The middle mesial root canal showed the greatest deviation compared with the MB and ML canals (P < .05). The apical foramina of mesial root canals of mandibular first molar teeth showed greater variations from each other and anatomic apices than previously reported. Clinically, the use of electronic apex locators for the detection of minor apical foramen of each mesial root canal is of the utmost important. Copyright © 2018 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Deep Phenotyping of Coarse Root Architecture in R. pseudoacacia Reveals That Tree Root System Plasticity Is Confined within Its Architectural Model

PubMed Central

Danjon, Frédéric; Khuder, Hayfa; Stokes, Alexia

2013-01-01

This study aims at assessing the influence of slope angle and multi-directional flexing and their interaction on the root architecture of Robinia pseudoacacia seedlings, with a particular focus on architectural model and trait plasticity. 36 trees were grown from seed in containers inclined at 0° (control) or 45° (slope) in a glasshouse. The shoots of half the plants were gently flexed for 5 minutes a day. After 6 months, root systems were excavated and digitized in 3D, and biomass measured. Over 100 root architectural traits were determined. Both slope and flexing increased significantly plant size. Non-flexed trees on 45° slopes developed shallow roots which were largely aligned perpendicular to the slope. Compared to the controls, flexed trees on 0° slopes possessed a shorter and thicker taproot held in place by regularly distributed long and thin lateral roots. Flexed trees on the 45° slope also developed a thick vertically aligned taproot, with more volume allocated to upslope surface lateral roots, due to the greater soil volume uphill. We show that there is an inherent root system architectural model, but that a certain number of traits are highly plastic. This plasticity will permit root architectural design to be modified depending on external mechanical signals perceived by young trees. PMID:24386227

Ammonium Inhibits Primary Root Growth by Reducing the Length of Meristem and Elongation Zone and Decreasing Elemental Expansion Rate in the Root Apex in Arabidopsis thaliana

PubMed Central

Gao, Kun; Chen, Fanjun; Yuan, Lixing; Mi, Guohua

2013-01-01

The inhibitory effect of ammonium on primary root growth has been well documented; however the underlying physiological and molecular mechanisms are still controversial. To avoid ammonium toxicity to shoot growth, we used a vertical two-layer split plate system, in which the upper layer contained nitrate and the lower layer contained ammonium. In this way, nitrogen status was maintained and only the apical part of the root system was exposed to ammonium. Using a kinematic approach, we show here that 1 mM ammonium reduces primary root growth, decreasing both elemental expansion and cell production. Ammonium inhibits the length of elongation zone and the maximum elemental expansion rate. Ammonium also decreases the apparent length of the meristem as well as the number of dividing cells without affecting cell division rate. Moreover, ammonium reduces the number of root cap cells but appears to affect neither the status of root stem cell niche nor the distal auxin maximum at the quiescent center. Ammonium also inhibits root gravitropism and concomitantly down-regulates the expression of two pivotal auxin transporters, AUX1 and PIN2. Insofar as ammonium inhibits root growth rate in AUX1 and PIN2 loss-of-function mutants almost as strongly as in wild type, we conclude that ammonium inhibits root growth and gravitropism by largely distinct pathways. PMID:23577185

Pollutant-induced cell death and reactive oxygen species accumulation in the aerial roots of Chinese banyan (Ficus microcarpa)

NASA Astrophysics Data System (ADS)

Liu, Nan; Cao, Ce; Sun, Zhongyu; Lin, Zhifang; Deng, Rufang

2016-11-01

Industrial pollutants induce the production of toxic reactive oxygen species (ROS) such as O2.-, H2O2, and ·OH in plants, but they have not been well quantified or localized in tissues and cells. This study evaluated the pollutant- (HSO3-, NH4NO3, Al3+, Zn2+, and Fe2+) induced toxic effects of ROS on the aerial roots of Chinese banyan (Ficus microcarpa). Root cell viability was greatly reduced by treatment with 20 mM NaHSO3, 20 mM NH4NO3, 0.2 mM AlCl3, 0.2 mM ZnSO4, or 0.2 mM FeSO4. Biochemical assay and histochemical localization showed that O2.- accumulated in roots in response to pollutants, except that the staining of O2.- under NaHSO3 treatment was not detective. Cytochemical localization further indicated that the generated O2.- was present mainly in the root cortex, and pith cells, especially in NH4NO3- and FeSO4-treated roots. The pollutants also caused greatly accumulated H2O2 and ·OH in aerial roots, which finally resulted in lipid peroxidation as indicated by increased malondialdehyde contents. We conclude that the F. microcarpa aerial roots are sensitive to pollutant-induced ROS and that the histochemical localization of O2.- via nitrotetrazolium blue chloride staining is not effective for detecting the effects of HSO3- treatment because of the treatment’s bleaching effect.

Nitric Oxide Is Associated with Long-Term Zinc Tolerance in Solanum nigrum1[W

PubMed Central

Xu, Jin; Yin, Hengxia; Li, Yulong; Liu, Xiaojing

2010-01-01

Nitric oxide (NO) has been identified as a signal molecule that interplays with reactive oxygen species in response to heavy metal stresses. Roles of NO in regulating cadmium toxicity and iron deficiency have been proposed; however, the function of NO in zinc (Zn) tolerance in plants remains unclear. Here, we investigated NO accumulation and its role in plant Zn tolerance. Zn-induced NO production promoted an increase in reactive oxygen species accumulation in Solanum nigrum roots by modulating the expression and activity of antioxidative enzymes. Subsequently, programmed cell death (PCD) was observed in primary root tips. Inhibiting NO accumulation by 2-phenyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide (a specific NO scavenger) or NG-nitro-l-arginine-methyl ester (a NO synthase inhibitor) prevented the increase of superoxide radical and hydrogen peroxide as well as the subsequent cell death in the root tips, supporting the role of NO in Zn-induced PCD in the root tips. Zn-induced NO production affected the length of primary roots, the number of lateral roots, and root hair growth and thereby modulated root system architecture and activity. Investigation of metal contents in Zn-treated roots suggests that NO is required for metal (especially iron) uptake and homeostasis in plants exposed to excess Zn. Taken together, our results indicate that NO production and the subsequent PCD in root tips exposed to excess Zn are favorable for the S. nigrum seedling response to long-term Zn toxicity by modulating root system architecture and subsequent adaptation to Zn stress. PMID:20855519

Water Transport Properties of Roots and Root Cortical Cells in Proton- and Al-Stressed Maize Varieties.

PubMed Central

Gunse, B.; Poschenrieder, C.; Barcelo, J.

1997-01-01

Root and root cell pressure-probe techniques were used to investigate the possible relationship between Al- or H+-induced alterations of the hydraulic conductivity of root cells (LPc) and whole-root water conductivity (LPr) in maize (Zea mays L.) plants. To distinguish between H+ and Al effects two varieties that differ in H+ and Al tolerance were assayed. Based on root elongation rates after 24 h in nutrient solution of pH 6.0, pH 4.5, or pH 4.5 plus 50 [mu]M Al, the variety Adour 250 was found to be H+-sensitive and Al-tolerant, whereas the variety BR 201 F was found to be H+-tolerant but Al-sensitive. No Al-induced decrease of root pressure and root cell turgor was observed in Al-sensitive BR 201 F, indicating that Al toxicity did not cause a general breakdown of membrane integrity and that ion pumping to the stele was maintained. Al reduced LPc more than LPr in Al-sensitive BR 201 F. Proton toxicity in Adour 250 affected LPr more than LPc. In this Al-tolerant variety LPc was increased by Al. Nevertheless, this positive effect on LPc did not render higher LPr values. In conclusion, there were no direct relationships between Al- or H+-induced decreases of LPr and the effects on LPc. To our knowledge, this is the first time that the influence of H+ and Al on root and root cell water relations has been directly measured by pressure-probe techniques. PMID:12223628

Investigating niche partitioning of ectomycorrhizal fungi in specialized rooting zones of the monodominant leguminous tree Dicymbe corymbosa.

PubMed

Smith, Matthew E; Henkel, Terry W; Williams, Gwendolyn C; Aime, M Catherine; Fremier, Alexander K; Vilgalys, Rytas

2017-07-01

Temperate ectomycorrhizal (ECM) fungi show segregation whereby some species dominate in organic layers and others favor mineral soils. Weak layering in tropical soils is hypothesized to decrease niche space and therefore reduce the diversity of ectomycorrhizal fungi. The Neotropical ECM tree Dicymbe corymbosa forms monodominant stands and has a distinct physiognomy with vertical crown development, adventitious roots and massive root mounds, leading to multi-stemmed trees with spatially segregated rooting environments: aerial litter caches, aerial decayed wood, organic root mounds and mineral soil. We hypothesized that these microhabitats host distinct fungal assemblages and therefore promote diversity. To test our hypothesis, we sampled D. corymbosa ectomycorrhizal root tips from the four microhabitats and analyzed community composition based on pyrosequencing of fungal internal transcribed spacer (ITS) barcode markers. Several dominant fungi were ubiquitous but analyses nonetheless suggested that communities in mineral soil samples were statistically distinct from communities in organic microhabitats. These data indicate that distinctive rooting zones of D. corymbosa contribute to spatial segregation of the fungal community and likely enhance fungal diversity. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

Dynamics of Aspen Roots Colonization by Pseudomonads Reveals Strain-Specific and Mycorrhizal-Specific Patterns of Biofilm Formation

PubMed Central

Noirot-Gros, Marie-Francoise; Shinde, Shalaka; Larsen, Peter E.; Zerbs, Sarah; Korajczyk, Peter J.; Kemner, Kenneth M.; Noirot, Philippe H.

2018-01-01

Rhizosphere-associated Pseudomonas fluorescens are known plant growth promoting (PGP) and mycorrhizal helper bacteria (MHB) of many plants and ectomycorrhizal fungi. We investigated the spatial and temporal dynamics of colonization of mycorrhizal and non-mycorrhizal Aspen seedlings roots by the P. fluorescens strains SBW25, WH6, Pf0-1, and the P. protegens strain Pf-5. Seedlings were grown in laboratory vertical plates systems, inoculated with a fluorescently labeled Pseudomonas strain, and root colonization was monitored over a period of 5 weeks. We observed unexpected diversity of bacterial assemblies on seedling roots that changed over time and were strongly affected by root mycorrhization. P. fluorescens SBW25 and WH6 stains developed highly structured biofilms with internal void spaces forming channels. On mycorrhizal roots bacteria appeared encased in a mucilaginous substance in which they aligned side by side in parallel arrangements. The different phenotypic classes of bacterial assemblies observed for the four Pseudomonas strains were summarized in a single model describing transitions between phenotypic classes. Our findings also reveal that bacterial assembly phenotypes are driven by interactions with mucilaginous materials present at roots. PMID:29774013

Waving and skewing: how gravity and the surface of growth media affect root development in Arabidopsis.

PubMed

Oliva, Michele; Dunand, Christophe

2007-01-01

Arabidopsis seedlings growing on inclined agar surfaces exhibit characteristic root behaviours called 'waving' and 'skewing': the former consists of a series of undulations, whereas the latter is a deviation from the direction of gravity. Even though the precise basis of these growth patterns is not well understood, both gravity and the contact between the medium and the root are considered to be the major players that result in these processes. The influence of these forces on root surface-dependent behaviours can be verified by growing seedlings at different gel pitches: plants growing on vertical plates present roots with slight waving and skewing when compared with seedlings grown on plates held at minor angles of < 90 degrees . However, other factors are thought to modulate root growth on agar; for instance, it has been demonstrated that the presence and concentration of certain compounds in the medium (such as sucrose) and of drugs able to modify the plant cell cytoskeleton also affect skewing and waving. The recent discovery of an active role of ethylene on surface-dependent root behaviour, and the finding of new mutants showing anomalous growth, pave the way for a more detailed description of these phenomena.

Strategic interaction among hospitals and nursing facilities: the efficiency effects of payment systems and vertical integration.

PubMed

Banks, D; Parker, E; Wendel, J

2001-03-01

Rising post-acute care expenditures for Medicare transfer patients and increasing vertical integration between hospitals and nursing facilities raise questions about the links between payment system structure, the incentive for vertical integration and the impact on efficiency. In the United States, policy-makers are responding to these concerns by initiating prospective payments to nursing facilities, and are exploring the bundling of payments to hospitals. This paper develops a static profit-maximization model of the strategic interaction between the transferring hospital and a receiving nursing facility. This model suggests that the post-1984 system of prospective payment for hospital care, coupled with nursing facility payments that reimburse for services performed, induces inefficient under-provision of hospital services and encourages vertical integration. It further indicates that the extension of prospective payment to nursing facilities will not eliminate the incentive to vertically integrate, and will not result in efficient production unless such integration takes place. Bundling prospective payments for hospitals and nursing facilities will neither remove the incentive for vertical integration nor induce production efficiency without such vertical integration. However, bundled payment will induce efficient production, with or without vertical integration, if nursing facilities are reimbursed for services performed. Copyright 2001 John Wiley & Sons, Ltd.

Psoralen production in hairy roots and adventitious roots cultures of Psoralea coryfolia.

PubMed

Baskaran, P; Jayabalan, N

2009-07-01

Psoralea corylifolia is an endangered plant producing various compounds of medical importance. Adventitious roots and hairy roots were induced in cultures prepared from hypocotyl explants. Psoralen content was evaluated in both root types grown either in suspension cultures or on agar solidified medium. Psoralen content was approximately 3 mg g(-1) DW in suspension grown hairy roots being higher than in solid grown hairy roots and in solid and suspension-grown adventitious roots.

Ammonium-induced loss of root gravitropism is related to auxin distribution and TRH1 function, and is uncoupled from the inhibition of root elongation in Arabidopsis.

PubMed

Zou, Na; Li, Baohai; Dong, Gangqiang; Kronzucker, Herbert J; Shi, Weiming

2012-06-01

Root gravitropism is affected by many environmental stresses, including salinity, drought, and nutrient deficiency. One significant environmental stress, excess ammonium (NH(4)(+)), is well documented to inhibit root elongation and lateral root formation, yet little is known about its effects on the direction of root growth. We show here that inhibition of root elongation upon elevation of external NH(4)(+) is accompanied by a loss in root gravitropism (agravitropism) in Arabidopsis. Addition of potassium (K(+)) to the treatment medium partially rescued the inhibition of root elongation by high NH(4)(+) but did not improve gravitropic root curvature. Expression analysis of the auxin-responsive reporter gene DR5::GUS revealed that NH(4)(+) treatment delayed the development of gravity-induced auxin gradients across the root cap but extended their duration once initiated. Moreover, the β-glucuronidase (GUS) signal intensity in root tip cells was significantly reduced under high NH(4)(+) treatment over time. The potassium carrier mutant trh1 displayed different patterns of root gravitropism and DR5::GUS signal intensity in root apex cells compared with the wild type in response to NH(4)(+). Together, the results demonstrate that the effects of NH(4)(+) on root gravitropism are related to delayed lateral auxin redistribution and the TRH1 pathway, and are largely independent of inhibitory effects on root elongation.

Characterization of fructose-bisphosphate aldolase regulated by gibberellin in roots of rice seedling.

PubMed

Konishi, Hirosato; Yamane, Hisakazu; Maeshima, Masayoshi; Komatsu, Setsuko

2004-12-01

Fructose-bisphosphate aldolase is a glycolytic enzyme whose activity increases in rice roots treated with gibberellin (GA). To investigate the relationship between aldolase and root growth, GA-induced root aldolase was characterized. GA3 promoted an increase in aldolase accumulation when 0.1 microM GA3 was added exogenously to rice roots. Aldolase accumulated abundantly in roots, especially in the apical region. To examine the effect of aldolase function on root growth, transgenic rice plants expressing antisense aldolase were constructed. Root growth of aldolase-antisense transgenic rice was repressed compared with that of the vector control transgenic rice. Although aldolase activity increased by 25% in vector control rice roots treated with 0.1 microM GA3, FBPA activity increased very little by 0.1 microM GA3 treatment in the root of aldolase-antisense transgenic rice. Furthermore, aldolase co-immunoprecipitated with antibodies against vacuolar H+ -ATPase in rice roots. In the root of OsCDPK13-antisense transgenic rice, aldolase did not accumulate even after treatment with GA3. These results suggest that the activation of glycolytic pathway function accelerates root growth and that GA3-induced root aldolase may be modulated through OsCDPK13. Aldolase physically associates with vacuolar H-ATPase in roots and may regulate the vacuolar H-ATPase mediated control of cell elongation that determines root length.

Clinical measurement of force systems upon activation of transpalatal arch in the treatment of unilateral crossbite.

PubMed

Yoshida, N; Koga, Y; Jost-Brinkmann, P G; Kobayashi, K

2003-01-01

in this study, forces and moments acting on the molars were theoretically determined by means of small-deflection analysis when an asymmetric third-order activation of the TPA was carried out. the transpalatal arch (TPA) is used to correct unilateral crossbites through the application of buccal root torque to the anchorage molar and lingual root torque to the contralateral molar in crossbite, combined with expansion. Unfortunately, the complex force systems created at the molars upon activation of the TPA cannot be easily estimated. our computations revealed that the vertical forces developed on the molars when both ends of the TPA are inserted into the lingual sheaths (two-couple system) is four-times greater than those when only one end is tied to the lingual sheath as a single-point contact (one-couple system). we propose a method of clinical estimation of the force system in a two-couple system by directly measuring the vertical force produced by the one-couple system.

A demographic analysis of vertical root fractures.

PubMed

Cohen, Stephen; Berman, Louis H; Blanco, Lucia; Bakland, Leif; Kim, Jay S

2006-12-01

Teeth with vertical root fractures (VRFs) have complete or incomplete fractures that extends through the enamel, dentin and pulp, down the long axis of the tooth. Several different variables were investigated and statistically evaluated as to their correlation with the presence of VRFs. Specifically analyzed were gender, tooth location, age, radiographic and clinical findings, bruxism, and pulpal status. The data were collected from three different endodontists, from three different geographic locations, comprising a total of 227 teeth. Although VRFs may occur in conjunction with any of the parameters investigated, only certain factors were found to occur in a significant number of cases. The results indicate that VRFs are statistically more prevalent in mandibular molars and maxillary premolars. They are associated with periradicular bone loss, pain to percussion, extensive restorations, and seem to occur more often in females and older patients. However, VRFs are not necessarily related to periapical bone loss, a widening of the periodontal ligament space, associated periodontal pockets, a sinus tract, particular pulpal status, or bruxism.

Investigation of the Fusarium virguliforme Transcriptomes Induced during Infection of Soybean Roots Suggests that Enzymes with Hydrolytic Activities Could Play a Major Role in Root Necrosis

PubMed Central

Sahu, Binod B.; Baumbach, Jordan L.; Singh, Prashant; Srivastava, Subodh K.; Yi, Xiaoping

2017-01-01

Sudden death syndrome (SDS) is caused by the fungal pathogen, Fusarium virguliforme, and is a major threat to soybean production in North America. There are two major components of this disease: (i) root necrosis and (ii) foliar SDS. Root symptoms consist of root necrosis with vascular discoloration. Foliar SDS is characterized by interveinal chlorosis and leaf necrosis, and in severe cases by flower and pod abscission. A major toxin involved in initiating foliar SDS has been identified. Nothing is known about how root necrosis develops. In order to unravel the mechanisms used by the pathogen to cause root necrosis, the transcriptome of the pathogen in infected soybean root tissues of a susceptible cultivar, ‘Essex’, was investigated. The transcriptomes of the germinating conidia and mycelia were also examined. Of the 14,845 predicted F. virguliforme genes, we observed that 12,017 (81%) were expressed in germinating conidia and 12,208 (82%) in mycelia and 10,626 (72%) in infected soybean roots. Of the 10,626 genes induced in infected roots, 224 were transcribed only following infection. Expression of several infection-induced genes encoding enzymes with oxidation-reduction properties suggests that degradation of antimicrobial compounds such as the phytoalexin, glyceollin, could be important in early stages of the root tissue infection. Enzymes with hydrolytic and catalytic activities could play an important role in establishing the necrotrophic phase. The expression of a large number of genes encoding enzymes with catalytic and hydrolytic activities during the late infection stages suggests that cell wall degradation could be involved in root necrosis and the establishment of the necrotrophic phase in this pathogen. PMID:28095498

Investigation of the Fusarium virguliforme Transcriptomes Induced during Infection of Soybean Roots Suggests that Enzymes with Hydrolytic Activities Could Play a Major Role in Root Necrosis.

PubMed

Sahu, Binod B; Baumbach, Jordan L; Singh, Prashant; Srivastava, Subodh K; Yi, Xiaoping; Bhattacharyya, Madan K

2017-01-01

Sudden death syndrome (SDS) is caused by the fungal pathogen, Fusarium virguliforme, and is a major threat to soybean production in North America. There are two major components of this disease: (i) root necrosis and (ii) foliar SDS. Root symptoms consist of root necrosis with vascular discoloration. Foliar SDS is characterized by interveinal chlorosis and leaf necrosis, and in severe cases by flower and pod abscission. A major toxin involved in initiating foliar SDS has been identified. Nothing is known about how root necrosis develops. In order to unravel the mechanisms used by the pathogen to cause root necrosis, the transcriptome of the pathogen in infected soybean root tissues of a susceptible cultivar, 'Essex', was investigated. The transcriptomes of the germinating conidia and mycelia were also examined. Of the 14,845 predicted F. virguliforme genes, we observed that 12,017 (81%) were expressed in germinating conidia and 12,208 (82%) in mycelia and 10,626 (72%) in infected soybean roots. Of the 10,626 genes induced in infected roots, 224 were transcribed only following infection. Expression of several infection-induced genes encoding enzymes with oxidation-reduction properties suggests that degradation of antimicrobial compounds such as the phytoalexin, glyceollin, could be important in early stages of the root tissue infection. Enzymes with hydrolytic and catalytic activities could play an important role in establishing the necrotrophic phase. The expression of a large number of genes encoding enzymes with catalytic and hydrolytic activities during the late infection stages suggests that cell wall degradation could be involved in root necrosis and the establishment of the necrotrophic phase in this pathogen.

Diurnal and seasonal variation in root xylem embolism in neotropical savanna woody species: impact on stomatal control of plant water status.

Treesearch

J-C. Domec; F.G. Scholz; S.J. Bucci; F.C. Meinzer; G. Goldstein; R. Villalobos-Vega

2006-01-01

Vulnerability to water-stress-induced embolism and variation in the degree of native embolism were measured in lateral roots of four co-occuring neotropical savanna tree species. Root embolism varied diurnally and seasonally. Late in the dry season, loss of root xylem conductivity reached 80% in the afternoon when root water potential (ψroot...

Subterranean, Herbivore-Induced Plant Volatile Increases Biological Control Activity of Multiple Beneficial Nematode Species in Distinct Habitats

PubMed Central

Ali, Jared G.; Alborn, Hans T.; Campos-Herrera, Raquel; Kaplan, Fatma; Duncan, Larry W.; Rodriguez-Saona, Cesar; Koppenhöfer, Albrecht M.; Stelinski, Lukasz L.

2012-01-01

While the role of herbivore-induced volatiles in plant-herbivore-natural enemy interactions is well documented aboveground, new evidence suggests that belowground volatile emissions can protect plants by attracting entomopathogenic nematodes (EPNs). However, due to methodological limitations, no study has previously detected belowground herbivore-induced volatiles in the field or quantified their impact on attraction of diverse EPN species. Here we show how a belowground herbivore-induced volatile can enhance mortality of agriculturally significant root pests. First, in real time, we identified pregeijerene (1,5-dimethylcyclodeca-1,5,7-triene) from citrus roots 9–12 hours after initiation of larval Diaprepes abbreviatus feeding. This compound was also detected in the root zone of mature citrus trees in the field. Application of collected volatiles from weevil-damaged citrus roots attracted native EPNs and increased mortality of beetle larvae (D. abbreviatus) compared to controls in a citrus orchard. In addition, field applications of isolated pregeijerene caused similar results. Quantitative real-time PCR revealed that pregeijerene increased pest mortality by attracting four species of naturally occurring EPNs in the field. Finally, we tested the generality of this root-zone signal by application of pregeijerene in blueberry fields; mortality of larvae (Galleria mellonella and Anomala orientalis) again increased by attracting naturally occurring populations of an EPN. Thus, this specific belowground signal attracts natural enemies of widespread root pests in distinct agricultural systems and may have broad potential in biological control of root pests. PMID:22761668

Responses of seminal wheat seedling roots to soil water deficits.

PubMed

Trejo, Carlos; Else, Mark A; Atkinson, Christopher J

2018-04-01

The aims of this paper are to develop our understanding of the ways by which soil water deficits influence early wheat root growth responses, particularly how seminal roots respond to soil drying and the extent to which information on differences in soil water content are conveyed to the shoot and their impact on shoot behaviour. To achieve this, wheat seedlings have been grown, individually for around 25 days after germination in segmented soil columns within vertical plastic compartments. Roots were exposed to different soil volumetric moisture contents (SVMC) within the two compartments. Experiments where the soil in the lower compartment was allowed to dry to different extents, while the upper was maintained close to field capacity, showed that wheat seedlings allocated proportionally more root dry matter to the lower drier soil compartment. The total production of root, irrespective of the upper or lower SVMC, was similar and there were no detected effects on leaf growth rate or gas exchange. The response of seminal roots to proportionally increase their allocation of dry matter, to the drier soil was unexpected with such plasticity of roots system development traditionally linked to heterogeneous nutrient distribution than accessing soil water. In experiments where the upper soil compartment was allowed to dry, root growth slowed and leaf growth and gas exchange declined. Subsequent experiments used root growth rates to determine when seminal root tips first came into contact with drying soil, with the intentions of determining how the observed root growth rates were maintained as an explanation for the observed changes in root allocation. Measurements of seminal root ABA and ethylene from roots within the drying soil are interpreted with respect to what is known about the physiological control of root growth in drying soil. Copyright © 2018 Elsevier GmbH. All rights reserved.

Rooting strategies in a subtropical savanna: a landscape-scale three-dimensional assessment.

PubMed

Zhou, Yong; Boutton, Thomas W; Wu, X Ben; Wright, Cynthia L; Dion, Anais L

2018-04-01

In resource-limited savannas, the distribution and abundance of fine roots play an important role in acquiring essential resources and structuring vegetation patterns and dynamics. However, little is known regarding the three-dimensional distribution of fine roots in savanna ecosystems at the landscape scale. We quantified spatial patterns of fine root density to a depth of 1.2 m in a subtropical savanna landscape using spatially specific sampling. Kriged maps revealed that fine root density was highest at the centers of woody patches, decreased towards the canopy edges, and reached lowest values within the grassland matrix throughout the entire soil profile. Lacunarity analyses indicated that spatial heterogeneities of fine root density decreased continuously to a depth of 50 cm and then increased in deeper portions of the soil profile across this landscape. This vertical pattern might be related to inherent differences in root distribution between trees/shrubs and herbaceous species, and the presence/absence of an argillic horizon across this landscape. The greater density of fine roots beneath woody patches in both upper and lower portions of the soil profile suggests an ability to acquire disproportionately more resources than herbaceous species, which may facilitate the development and persistence of woody patches across this landscape.

The anatomical relationship between the roots of mandibular second molars and the inferior alveolar nerve.

PubMed

Chong, B S; Quinn, A; Pawar, R R; Makdissi, J; Sidhu, S K

2015-06-01

To evaluate the anatomical relationship between the roots of mandibular second molars and the inferior alveolar nerve (IAN) in relation to the risk of potential nerve injury during root canal treatment. Cone-beam computed tomography (CBCT) images from the patient record database at a dental hospital were selected. The anonymized CBCT images were reconstructed and examined in three planes (coronal, axial and sagittal) using 3D viewing software. The relationship between each root apex of mandibular second molars and the IAN was evaluated by measuring the horizontal and vertical distances from coronal CBCT sections, and the actual distance was then calculated mathematically using Pythagoras' theorem. In 55% of the 272 mandibular second molar roots evaluated, from a total of 134 scans, the distance between the anatomical root apex and the IAN was ≤3 mm. In over 50% of the cases evaluated, there was an intimate relationship between the roots of mandibular second molars and the inferior alveolar nerve (IAN). Therefore, root canal treatment of mandibular second molars may pose a more significant potential risk of IAN injury; necessary precautions should be exercised, and the prudent use of CBCT should be considered if an intimate relationship is suspected. © 2014 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Regulation of root hair initiation and expansin gene expression in Arabidopsis

NASA Technical Reports Server (NTRS)

Cho, Hyung-Taeg; Cosgrove, Daniel J.

2002-01-01

The expression of two Arabidopsis expansin genes (AtEXP7 and AtEXP18) is tightly linked to root hair initiation; thus, the regulation of these genes was studied to elucidate how developmental, hormonal, and environmental factors orchestrate root hair formation. Exogenous ethylene and auxin, as well as separation of the root from the medium, stimulated root hair formation and the expression of these expansin genes. The effects of exogenous auxin and root separation on root hair formation required the ethylene signaling pathway. By contrast, blocking the endogenous ethylene pathway, either by genetic mutations or by a chemical inhibitor, did not affect normal root hair formation and expansin gene expression. These results indicate that the normal developmental pathway for root hair formation (i.e., not induced by external stimuli) is independent of the ethylene pathway. Promoter analyses of the expansin genes show that the same promoter elements that determine cell specificity also determine inducibility by ethylene, auxin, and root separation. Our study suggests that two distinctive signaling pathways, one developmental and the other environmental/hormonal, converge to modulate the initiation of the root hair and the expression of its specific expansin gene set.

Antisense expression of an Arabidopsis ran binding protein renders transgenic roots hypersensitive to auxin and alters auxin-induced root growth and development by arresting mitotic progress

NASA Technical Reports Server (NTRS)

Kim, S. H.; Arnold, D.; Lloyd, A.; Roux, S. J.

2001-01-01

We cloned a cDNA encoding an Arabidopsis Ran binding protein, AtRanBP1c, and generated transgenic Arabidopsis expressing the antisense strand of the AtRanBP1c gene to understand the in vivo functions of the Ran/RanBP signal pathway. The transgenic plants showed enhanced primary root growth but suppressed growth of lateral roots. Auxin significantly increased lateral root initiation and inhibited primary root growth in the transformants at 10 pM, several orders of magnitude lower than required to induce these responses in wild-type roots. This induction was followed by a blockage of mitosis in both newly emerged lateral roots and in the primary root, ultimately resulting in the selective death of cells in the tips of both lateral and primary roots. Given the established role of Ran binding proteins in the transport of proteins into the nucleus, these findings are consistent with a model in which AtRanBP1c plays a key role in the nuclear delivery of proteins that suppress auxin action and that regulate mitotic progress in root tips.

Subsurface flow and vegetation patterns in tidal environments

NASA Astrophysics Data System (ADS)

Ursino, Nadia; Silvestri, Sonia; Marani, Marco

2004-05-01

Tidal environments are characterized by a complex interplay of hydrological, geomorphic, and biological processes, and their understanding and modeling thus require the explicit description of both their biotic and abiotic components. In particular, the presence and spatial distribution of salt marsh vegetation (a key factor in the stabilization of the surface soil) have been suggested to be related to topographic factors and to soil moisture patterns, but a general, process-based comprehension of this relationship has not yet been achieved. The present paper describes a finite element model of saturated-unsaturated subsurface flow in a schematic salt marsh, driven by tidal fluctuations and evapotranspiration. The conditions leading to the establishment of preferentially aerated subsurface zones are studied, and inferences regarding the development and spatial distribution of salt marsh vegetation are drawn, with important implications for the overall ecogeomorphological dynamics of tidal environments. Our results show that subsurface water flow in the marsh induces complex water table dynamics, even when the tidal forcing has a simple sinusoidal form. The definition of a space-dependent aeration time is then proposed to characterize root aeration. The model shows that salt marsh subsurface flow depends on the distance from the nearest creek or channel and that the subsurface water movement near tidal creeks is both vertical and horizontal, while farther from creeks, it is primarily vertical. Moreover, the study shows that if the soil saturated conductivity is relatively low (10-6 m s-1, values quite common in salt marsh areas), a persistently unsaturated zone is present below the soil surface even after the tide has flooded the marsh; this provides evidence of the presence of an aerated layer allowing a prolonged presence of oxygen for aerobic root respiration. The results further show that plant transpiration increases the extent and persistence of the aerated layer, thereby introducing a strong positive feedback: Pioneer plants on marsh edges have the effect of increasing soil oxygen availability, thus creating the conditions for the further development of other plant communities.

Displacement of organelles in plant gravireceptor cells by vibrational forces and ultrasound.

NASA Astrophysics Data System (ADS)

Kuznetsov, O.; Nechitailo, G.; Kuznetsov, A.

Plant gravity perception can be studied by displacing statoliths inside receptor cells by forces other than gravity. Due to mechanical heterogeneity of statocytes various ponderomotive forces can be used for this purpose. In a plant subjected to non- symmetric vibrations statoliths experience inertial force proportional to the difference between their density and that of cytoplasm and to the instantaneous acceleration of the cell. This force causes cyclic motion of statoliths relative to cytoplasm and, depending on the profile of oscillations, can result in a net displacement of them (due to complex rheology of the cell interior), similar to sedimentation. This can be described as "vibrational" ponderomotive force acting on the statoliths. Vertically growing Arabidopsis seedlings, subjected to horizontal, sawtooth shaped oscillations (250 Hz, 1.5 mm amplitude), showed 17+/-2o root curvature toward and shoot curvature of 11+/-3o against the stronger acceleration. When the polarity of the oscillations was reversed, the direction of curvature of shoots and roots was also reversed. Control experiments with starchless mutants (TC7) produced no net curvature, which indicates that dense starch-filled amyloplasts are needed for the effect. These control experiments also eliminate touch-induced reactions or other side-effects as the cause of the curvature. Linum roots curved 25+/-7o . Ceratodon protonemata subjected to the same oscillations have shown displacement of plastids and curvature consistent with the pattern observed during graviresponse: positively gravitropic wwr mutant curved in the direction of the plastid displacement, WT curved in the opposite direction. Acoustic ponderomotive forces, originating from transfer of a sonic beam momentum to the medium due to sound scattering and attenuation in a mechanically heterogeneous system, also can displace statoliths. Vertical flax seedlings curved away from the ultrasonic source (800 kHz, 0.1 W/cm2 ) presumably as a reaction to amyloplasts displacement by acoustic forces. Besides investigating the graviperception mechanism, vibrational and acoustic forces can serve as tools for analyzing mechanical properties of cell interior. Practical applications of this technology could include providing directional stimuli for plants in microgravity by low doses of vibrations. Vibrations present on board of spacecraft may have vectorial effects on plants and other organisms, and their influence should be assessed.

Concurrent synthesis and release of nod-gene-inducing flavonoids from alfalfa roots. [Medicago sativa L. ; Rhizobium meliloti

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maxwell, C.A.; Phillips, D.A.

Flavonoid signals from alfalfa (Medicago sativa L.) induce transcription of nodulation (nod) genes in Rhizobium meliloti. Alfalfa roots release three major nod-gene inducers: 4{prime},7-dihydroxyflavanone, 4{prime},7-dihydroxyflavone, and 4,4{prime}-dihydroxy-2{prime}-methoxychalcone. The objective of the present study was to define temporal relationships between synthesis and exudation for those flavonoids. Requirements for concurrent flavonoid biosynthesis were assessed by treating roots of intact alfalfa seedlings with (U-{sup 14}C)-L-phenylalanine in the presence or absence of the phenylalanine ammonia-lyase inhibitor L-2-aminoxy-3-phenylpropionic acid (AOPP). In the absence of AOPP, each of the three flavonoids in exudates contained {sup 14}C. In the presence of AOPP, {sup 14}C labeling and releasemore » of all the exuded nod-gene inducers were reduced significantly. AOPP inhibited labeling and release of the strongest nod-gene inducer, methoxychalcone, by more than 90%. The release process responsible for exudation of nod-gene inducers appears to be specific rather than a general phenomenon such as a sloughing off of cells during root growth.« less

Effects of abscisic acid and xanthoxin on elongation and gravitropism in primary roots of Zea mays

NASA Technical Reports Server (NTRS)

Lee, J. S.; Hasenstein, K. H.; Mulkey, T. J.; Yang, R. L.; Evans, M. L.

1990-01-01

We examined the involvement of abscisic acid (ABA) and xanthoxin (Xan) in maize root gravitropism by (1) testing the ability of ABA to allow positive gravitropism in dark-grown seedlings of the maize cultivar LG11, a cultivar known to require light for positive gravitropism of the primary root, (2) comparing curvature in roots in which half of the cap had been excised and replaced with agar containing either ABA or indole-3-acetic acid (IAA), (3) measuring gravitropism in roots of seedlings submerged in oxygenated solutions of ABA or IAA and (4) testing the effect of Xan on root elongation. Using a variety of methods of applying ABA to the root, we found that ABA did not cause horizontally-oriented primary roots of dark-grown seedlings to become positively gravitropic. Replacing half of the root cap of vertically oriented roots with an agar block containing ABA had little or no effect on curvature relative to that of controls in which the half cap was replaced by a plain agar block. Replacement of the removed half cap with IAA either canceled or reversed the curvature displayed by controls. When light-grown seedlings were submerged in ABA they responded strongly to gravistimulation while those in IAA did not. Xan (up to 0.1 mM) did not affect root elongation. The results indicate that ABA is not a likely mediator of root gravitropism and that the putative ABA precursor, Xan, lacks the appropriate growth-inhibiting properties to serve as a mediator of root gravitropism.

X-ray computed tomography uncovers root-root interactions: quantifying spatial relationships between interacting root systems in three dimensions.

PubMed

Paya, Alexander M; Silverberg, Jesse L; Padgett, Jennifer; Bauerle, Taryn L

2015-01-01

Research in the field of plant biology has recently demonstrated that inter- and intra-specific interactions belowground can dramatically alter root growth. Our aim was to answer questions related to the effect of inter- vs. intra-specific interactions on the growth and utilization of undisturbed space by fine roots within three dimensions (3D) using micro X-ray computed tomography. To achieve this, Populus tremuloides (quaking aspen) and Picea mariana (black spruce) seedlings were planted into containers as either solitary individuals, or inter-/intra-specific pairs, allowed to grow for 2 months, and 3D metrics developed in order to quantify their use of belowground space. In both aspen and spruce, inter-specific root interactions produced a shift in the vertical distribution of the root system volume, and deepened the average position of root tips when compared to intra-specifically growing seedlings. Inter-specific interactions also increased the minimum distance between root tips belonging to the same root system. There was no effect of belowground interactions on the radial distribution of roots, or the directionality of lateral root growth for either species. In conclusion, we found that significant differences were observed more often when comparing controls (solitary individuals) and paired seedlings (inter- or intra-specific), than when comparing inter- and intra-specifically growing seedlings. This would indicate that competition between neighboring seedlings was more responsible for shifting fine root growth in both species than was neighbor identity. However, significant inter- vs. intra-specific differences were observed, which further emphasizes the importance of biological interactions in competition studies.

[Root system distribution and biomechanical characteristics of Bambusa oldhami].

PubMed

Zhou, Ben-Zhi; Xu, Sheng-Hua; An, Yan-Fei; Xu, Sheng-Hua

2014-05-01

To determine the mechanism of soil stabilizing through Bambusa oldhami root system, the vertical distribution of B. oldhami root system in soil was investigated, and the tensile strength of individual root and soil shear strength were measured in B. oldhami forest. The dry mass, length, surface area and volume of the B. oldhami root system decreased with the increasing soil depth, with more than 90% of the root system occurring in the 0-40 cm soil layer. The root class with D 1 mm occupied the highest percentage of the total in terms of root length, accounting for 79.6%, but the lowest percentage of the total in terms of root volume, accounting for 8.2%. The root class with D >2 mm was the opposite, and the root class with D= 1-2 mm stayed in between. The maximum tensile resistance of B. oldhami root, either with 12% moisture content or a saturated moisture content, increased with the increasing root diameter, while the tensile strength decreased with the increasing root diameter in accordance with power function. Tensile strength of the root, with either of the two moisture contents, was significantly different among the diameter classes, with the highest tensile strength occurring in the root with D < or = 1 mm and the lowest in the root with D > or = 2 mm. The tensile strength of root with 12% moisture content was significantly higher than that with the saturated moisture content, and less effect of moisture content on root tensile strength would occur in thicker roots. The shear strengths of B. oldhami forest soil and of bare soil both increased with the increasing soil depth. The shear strength of B. oldhami forest soil had a linear positive correlation with the root content in soil, and was significantly higher than that of bare soil. The shear strength increment in B. oldhami forest was positively correlated with the root content in soil according to an exponential function, but not related significantly with soil depth.

Hormonal changes in relation to biomass partitioning and shoot growth impairment in salinized tomato (Solanum lycopersicum L.) plants.

PubMed

Albacete, Alfonso; Ghanem, Michel Edmond; Martínez-Andújar, Cristina; Acosta, Manuel; Sánchez-Bravo, José; Martínez, Vicente; Lutts, Stanley; Dodd, Ian C; Pérez-Alfocea, Francisco

2008-01-01

Following exposure to salinity, the root/shoot ratio is increased (an important adaptive response) due to the rapid inhibition of shoot growth (which limits plant productivity) while root growth is maintained. Both processes may be regulated by changes in plant hormone concentrations. Tomato plants (Solanum lycopersicum L. cv Moneymaker) were cultivated hydroponically for 3 weeks under high salinity (100 mM NaCl) and five major plant hormones (abscisic acid, ABA; the cytokinins zeatin, Z, and zeatin-riboside, ZR; the auxin indole-3-acetic acid, IAA; and the ethylene precursor 1-aminocyclopropane-1-carboxylic acid, ACC) were determined weekly in roots, xylem sap, and leaves. Salinity reduced shoot biomass by 50-60% and photosynthetic area by 20-25% both by decreasing leaf expansion and delaying leaf appearance, while root growth was less affected, thus increasing the root/shoot ratio. ABA and ACC concentrations strongly increased in roots, xylem sap, and leaves after 1 d (ABA) and 15 d (ACC) of salinization. By contrast, cytokinins and IAA were differentially affected in roots and shoots. Salinity dramatically decreased the Z+ZR content of the plant, and induced the conversion of ZR into Z, especially in the roots, which accounted for the relative increase of cytokinins in the roots compared to the leaf. IAA concentration was also strongly decreased in the leaves while it accumulated in the roots. Decreased cytokinin content and its transport from the root to the shoot were probably induced by the basipetal transport of auxin from the shoot to the root. The auxin/cytokinin ratio in the leaves and roots may explain both the salinity-induced decrease in shoot vigour (leaf growth and leaf number) and the shift in biomass allocation to the roots, in agreement with changes in the activity of the sink-related enzyme cell wall invertase.

Stereomicroscopic evaluation of dentinal defects induced by new rotary system: "ProTaper NEXT".

PubMed

Shori, Deepa Deepak; Shenoi, Pratima Ramakrishna; Baig, Arshia R; Kubde, Rajesh; Makade, Chetana; Pandey, Swapnil

2015-01-01

The objective of this study was to evaluate dentinal defects formed by new rotary system - Protaper next™ (PTN). Sixty single-rooted premolars were selected. All specimens were decoronated and divided into four groups, each group having 15 specimens. Group I specimens were prepared by Hand K-files (Mani), Group II with ProTaper Universal (PT; Dentsply Maillefer), Group III with Hero Shaper (HS; Micro-Mega, Besancon, France), and Group IV with PTN (Dentsply Maillefer). Roots of each specimen were sectioned at 3, 6, and 9mm from the apex and were then viewed under a stereomicroscope to evaluate presence or absence of dentinal defects. In roots prepared with hand files (HFs) showed lowest percentage of dentinal defects (6.7%); whereas in roots prepared with PT, HS, and PTN it was 40, 66.7, and 26.7%, respectively. There was significant difference between the HS group and the PTN group (P < 0.05). All rotary files induced defects in root dentin, whereas the hand instruments induced minimal defects.

Red-light-induced positive phototropism in Arabidopsis roots

NASA Technical Reports Server (NTRS)

Ruppel, N. J.; Hangarter, R. P.; Kiss, J. Z.

2001-01-01

The interaction between light and gravity is critical in determining the final form of a plant. For example, the competing activities of gravitropism and phototropism can determine the final orientation of a stem or root. The results reported here indicate that, in addition to the previously described blue-light-dependent negative phototropic response in roots, roots of Arahidopsis thaliana (L.) Heynh. display a previously unknown red-light-dependent positive phototropic response. Both phototropic responses in roots are considerably weaker than the graviresponse, which often masks phototropic curvature. However, through the use of mutant strains with impaired gravitropism, we were able to identify a red-light-dependent positive phototropic response in Arabidopsis roots. The red-induced positive phototropic response is considerably weaker than the blue-light response and is barely detectable in plants with a normal gravitropic response.

Red-light-induced positive phototropism in Arabidopsis roots.

PubMed

Ruppel, N J; Hangarter, R P; Kiss, J Z

2001-02-01

The interaction between light and gravity is critical in determining the final form of a plant. For example, the competing activities of gravitropism and phototropism can determine the final orientation of a stem or root. The results reported here indicate that, in addition to the previously described blue-light-dependent negative phototropic response in roots, roots of Arahidopsis thaliana (L.) Heynh. display a previously unknown red-light-dependent positive phototropic response. Both phototropic responses in roots are considerably weaker than the graviresponse, which often masks phototropic curvature. However, through the use of mutant strains with impaired gravitropism, we were able to identify a red-light-dependent positive phototropic response in Arabidopsis roots. The red-induced positive phototropic response is considerably weaker than the blue-light response and is barely detectable in plants with a normal gravitropic response.

AOX1-Subfamily Gene Members in Olea europaea cv. "Galega Vulgar"-Gene Characterization and Expression of Transcripts during IBA-Induced in Vitro Adventitious Rooting.

PubMed

Velada, Isabel; Grzebelus, Dariusz; Lousa, Diana; M Soares, Cláudio; Santos Macedo, Elisete; Peixe, Augusto; Arnholdt-Schmitt, Birgit; G Cardoso, Hélia

2018-02-17

Propagation of some Olea europaea L. cultivars is strongly limited due to recalcitrant behavior in adventitious root formation by semi-hardwood cuttings. One example is the cultivar "Galega vulgar". The formation of adventitious roots is considered a morphological response to stress. Alternative oxidase (AOX) is the terminal oxidase of the alternative pathway of the plant mitochondrial electron transport chain. This enzyme is well known to be induced in response to several biotic and abiotic stress situations. This work aimed to characterize the alternative oxidase 1 (AOX1)-subfamily in olive and to analyze the expression of transcripts during the indole-3-butyric acid (IBA)-induced in vitro adventitious rooting (AR) process. OeAOX1a (acc. no. MF410318) and OeAOX1d (acc. no. MF410319) were identified, as well as different transcript variants for both genes which resulted from alternative polyadenylation events. A correlation between transcript accumulation of both OeAOX1a and OeAOX1d transcripts and the three distinct phases (induction, initiation, and expression) of the AR process in olive was observed. Olive AOX1 genes seem to be associated with the induction and development of adventitious roots in IBA-treated explants. A better understanding of the molecular mechanisms underlying the stimulus needed for the induction of adventitious roots may help to develop more targeted and effective rooting induction protocols in order to improve the rooting ability of difficult-to-root cultivars.

The Cyclic Nucleotide-Gated Channel CNGC14 Regulates Root Gravitropism in Arabidopsis thaliana.

PubMed

Shih, Han-Wei; DePew, Cody L; Miller, Nathan D; Monshausen, Gabriele B

2015-12-07

In plant roots, auxin inhibits cell expansion, and an increase in cellular auxin levels on the lower flanks of gravistimulated roots suppresses growth and thereby causes downward bending. These fundamental features of root growth responses to auxin were first described over 80 years ago, but our understanding of the underlying molecular mechanisms has remained scant. Here, we report that CYCLIC NUCLEOTIDE-GATED CHANNEL 14 (CNGC14) is essential for the earliest phase of auxin-induced ion signaling and growth inhibition in Arabidopsis roots. Using a fluorescence-imaging-based genetic screen, we found that cngc14 mutants exhibit a complete loss of rapid Ca(2+) and pH signaling in response to auxin treatment. Similarly impaired ion signaling was observed upon gravistimulation. We further developed a kinematic analysis approach to study dynamic root growth responses to auxin at high spatiotemporal resolution. These analyses revealed that auxin-induced growth inhibition and gravitropic bending are significantly delayed in cngc14 compared to wild-type roots, where auxin suppresses cell expansion within 1 min of treatment. Finally, we demonstrate that auxin-induced cytosolic Ca(2+) changes are required for rapid growth inhibition. Our results support a direct role for CNGC14-dependent Ca(2+) signaling in regulating the early posttranscriptional phase of auxin growth responses in Arabidopsis roots. Copyright © 2015 Elsevier Ltd. All rights reserved.

Foveal Curvature and Asymmetry Assessed Using Optical Coherence Tomography.

PubMed

VanNasdale, Dean A; Eilerman, Amanda; Zimmerman, Aaron; Lai, Nicky; Ramsey, Keith; Sinnott, Loraine T

2017-06-01

The aims of this study were to use cross-sectional optical coherence tomography imaging and custom curve fitting software to evaluate and model the foveal curvature as a spherical surface and to compare the radius of curvature in the horizontal and vertical meridians and test the sensitivity of this technique to anticipated meridional differences. Six 30-degree foveal-centered radial optical coherence tomography cross-section scans were acquired in the right eye of 20 clinically normal subjects. Cross sections were manually segmented, and custom curve fitting software was used to determine foveal pit radius of curvature using the central 500, 1000, and 1500 μm of the foveal contour. Radius of curvature was compared across different fitting distances. Root mean square error was used to determine goodness of fit. The radius of curvature was compared between the horizontal and vertical meridians for each fitting distance. There radius of curvature was significantly different when comparing each of the three fitting distances (P < .01 for each comparison). The average radii of curvature were 970 μm (95% confidence interval [CI], 913 to 1028 μm), 1386 μm (95% CI, 1339 to 1439 μm), and 2121 μm (95% CI, 2066 to 2183) for the 500-, 1000-, and 1500-μm fitting distances, respectively. Root mean square error was also significantly different when comparing each fitting distance (P < .01 for each comparison). The average root mean square errors were 2.48 μm (95% CI, 2.41 to 2.53 μm), 6.22 μm (95% CI, 5.77 to 6.60 μm), and 13.82 μm (95% CI, 12.93 to 14.58 μm) for the 500-, 1000-, and 1500-μm fitting distances, respectively. The radius of curvature between the horizontal and vertical meridian radii was statistically different only in the 1000- and 1500-μm fitting distances (P < .01 for each), with the horizontal meridian being flatter than the vertical. The foveal contour can be modeled as a sphere with low curve fitting error over a limited distance and capable of detecting subtle foveal contour differences between meridians.

Gentiolactone, a Secoiridoid Dilactone from Gentiana triflora, Inhibits TNF-α, iNOS and Cox-2 mRNA Expression and Blocks NF-κB Promoter Activity in Murine Macrophages

PubMed Central

Yamada, Hidetoshi; Kikuchi, Sayaka; Inui, Tomoki; Takahashi, Hideyuki; Kimura, Ken-ichi

2014-01-01

Background Gentian roots have been used as a herbal medicine because of their anti-inflammatory activities. However, the molecular mechanisms of these anti-inflammatory effects remain to be completely explained. Methods and Findings Here, we investigated anti-inflammatory effects of gentian roots and showed that root extracts from Gentiana triflora inhibited lipopolysaccharide (LPS)-induced expression of TNF-α in RAW264.7 cells. The extracts also contained swertiamarin and gentiopicroside, which are the major active compounds of gentian roots; however, neither compound had any effect on LPS-induced TNF-α production in our test system. We isolated gentiolactone as an inhibitor of TNF-α production from the extracts. Gentiolactone also inhibited LPS-induced inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (Cox-2) expression at the mRNA level. Moreover, gentiolactone suppressed NF-κB transcriptional activity without inhibition of IκB degradation or NF-κB nuclear transport. Conclusions Our results indicate that inhibition of TNF-α, iNOS and Cox-2 expression by gentiolactone is one of the mechanisms of the anti-inflammatory properties of gentian roots. PMID:25423092

The effect of acetylshikonin isolated from Lithospermum canescens roots on tumor-induced cutaneous angiogenesis.

PubMed

Pietrosiuk, Agnieszka; Furmanowa, Mirosława; Skopińiska-Rózewska, Ewa; Sommer, Ewa; Skurzak, Henryk; Bany, Janusz

2004-01-01

This study has demonstrated that acetylshikonin (ACS), the isolated ingredient from Lithospermum canescens Lehm. roots, in a daily dose of 200 microg for 3 days, inhibited cutaneous angiogenesis induced by L-1 sarcoma cells in Balb/c mice.

Sending mixed messages: a trophic cascade produced by a belowground herbivore-induced cue

USDA-ARS?s Scientific Manuscript database

Plants defend themselves against herbivores both directly (chemical toxins and physical barriers) and indirectly (attracting natural enemies of their herbivores). Previous work has shown that roots of citrus defend themselves against root herbivores by releasing an herbivore induced plant volatile (...

Ice cap melting and low viscosity crustal root explain narrow geodetic uplift of the Western Alps

NASA Astrophysics Data System (ADS)

Chery, Jean; Genti, Manon; Vernant, Philippe

2016-04-01

More than 10 years of geodetic measurements demonstrate an uplift rate of 1-3 mm/yr of the high topography region of the Western Alps. By contrast, no significant horizontal motion has been detected. Three uplift mechanisms have been proposed so far: (1) the isostatic response to denudation. However this process is responsible for only a fraction of the observed uplift and (2) the rebound induced by the Wurmian ice cap melting. This process leads to a broader uplifting region than the one evidenced by geodetic observations. (3) a deep source motion associated with slab motion or some deep isostatic unbalance. Using a numerical model accounting for crustal and mantle rheology of the Alps and its foreland, we model the response to Wurmian ice cap melting. We show that a crustal viscosity contrast between the foreland and the central part of the Alps, the later being weaker with a viscosity of 1021 Pa.s, is needed to produce a narrow uplift. The vertical rates are enhanced if the strong uppermost mantle beneath the Moho is interrupted across the Alps, therefore allowing a weak vertical rheological anomaly thanks to the continuity between the low viscosity parts of the crust and mantle. References: Champagnac, J.-D., F. Schlunegger, K. Norton, F. von Blanckenburg, L. M. Abbühl, and M. Schwab (2009), Erosion-driven uplift of the modern Central Alps, Tectonophysics, 474(1-2), 236-249. Vernant, P., F. Hivert, J. Chéry, P. Steer, R. Cattin, and A. Rigo (2013), Erosion-induced isostatic rebound triggers extension in low convergent mountain ranges, geology, 41(4), 467-470.

Characterization of LeMir, a Root-Knot Nematode-Induced Gene in Tomato with an Encoded Product Secreted from the Root1

PubMed Central

Brenner, Eric D.; Lambert, Kris N.; Kaloshian, Isgouhi; Williamson, Valerie M.

1998-01-01

A tomato gene that is induced early after infection of tomato (Lycopersicon esculentum Mill.) with root-knot nematodes (Meloidogyne javanica) encodes a protein with 54% amino acid identity to miraculin, a flavorless protein that causes sour substances to be perceived as sweet. This gene was therefore named LeMir (L. esculentum miraculin). Sequence similarity places the encoded protein in the soybean trypsin-inhibitor family (Kunitz). LeMir mRNA is found in root, hypocotyl, and flower tissues, with the highest expression in the root. Rapid induction of expression upon nematode infection is localized to root tips. In situ hybridization shows that LeMir is expressed constitutively in the root-cap and root-tip epidermis. The LeMir protein product (LeMir) was produced in the yeast Pichia pastoris for generation of antibodies. Western-blot analysis showed that LeMir expression is up-regulated by nematode infection and by wounding. LeMir is also expressed in tomato callus tissue. Immunoprint analysis revealed that LeMir is expressed throughout the seedling root, but that levels are highest at the root/shoot junction. Analysis of seedling root exudates revealed that LeMir is secreted from the root into the surrounding environment, suggesting that it may interact with soil-borne microorganisms. PMID:9733543

Jasmonate signaling is activated in the very early stages of iron deficiency responses in rice roots.

PubMed

Kobayashi, Takanori; Itai, Reiko Nakanishi; Senoura, Takeshi; Oikawa, Takaya; Ishimaru, Yasuhiro; Ueda, Minoru; Nakanishi, Hiromi; Nishizawa, Naoko K

2016-07-01

Under low iron availability, plants induce the expression of various genes involved in iron uptake and translocation at the transcriptional level. This iron deficiency response is affected by various plant hormones, but the roles of jasmonates in this response are not well-known. We investigated the involvement of jasmonates in rice iron deficiency responses. High rates of jasmonate-inducible genes were induced during the very early stages of iron deficiency treatment in rice roots. Many jasmonate-inducible genes were also negatively regulated by the ubiquitin ligases OsHRZ1 and OsHRZ2 and positively regulated by the transcription factor IDEF1. Ten out of 35 genes involved in jasmonate biosynthesis and signaling were rapidly induced at 3 h of iron deficiency treatment, and this induction preceded that of known iron deficiency-inducible genes involved in iron uptake and translocation. Twelve genes involved in jasmonate biosynthesis and signaling were also upregulated in HRZ-knockdown roots. Endogenous concentrations of jasmonic acid and jasmonoyl isoleucine tended to be rapidly increased in roots in response to iron deficiency treatment, whereas these concentrations were higher in HRZ-knockdown roots under iron-sufficient conditions. Analysis of the jasmonate-deficient cpm2 mutant revealed that jasmonates repress the expression of many iron deficiency-inducible genes involved in iron uptake and translocation under iron sufficiency, but this repression is partly canceled under an early stage of iron deficiency. These results indicate that jasmonate signaling is activated during the very early stages of iron deficiency, which is partly regulated by IDEF1 and OsHRZs.

Platelet inhibitory effects of juices from Pachyrhizus erosus L. root and Psidium guajava L. fruit: a randomized controlled trial in healthy volunteers.

PubMed

Thaptimthong, Thitiporn; Kasemsuk, Thitima; Sibmooh, Nathawut; Unchern, Supeenun

2016-08-03

The purpose of this study is to investigate cardiovascular benefits of juices obtained from two commonly consumed fruits in Thailand, Pachyrhizus erosus, L. (yam bean) and Psidium guajava, L. (guava), by examining their acute cardiovascular effects in healthy volunteers. Possible involvements of the dietary nitrate on their effects were investigated as well. Thirty healthy volunteers were randomly divided into three groups of 10 subjects per group and each group was allocated to drink 500 ml of freshly prepared yam bean root juice, guava fruit juice, or water. Systemic nitrate and nitrite concentrations, heart rate, systolic and diastolic blood pressure, serum K(+) concentrations, ex vivo platelet aggregation, and plasma cGMP concentrations were monitored at the baseline and at various time points after the intake of juices or water. Data were compared by repeated measures ANOVA. Following the ingestion of both yam bean root juice and guava fruit juice, collagen-induced but not ADP-induced platelet aggregation was attenuated. Ingestion of yam bean root juice increased systemic nitrate and nitrite concentrations whereby elevated nitrite concentrations correlated with the extent of inhibiting collagen-induced platelet aggregation. In addition, positive correlation between systemic nitrite and plasma cGMP concentrations and negative correlation between plasma cGMP concentrations and the extent of collagen-induced platelet aggregation were revealed. Nevertheless, yam bean root juice reduced only diastolic blood pressure while guava fruit juice reduced heart rate, systolic and diastolic blood pressure. The present study has illustrated, for the first time, acute inhibitory effects of yam bean root juice and guava fruit juice on ex vivo collagen-induced platelet aggregation in healthy subjects. Dietary nitrate was shown to underlie the effect of yam bean root juice but not that of guava fruit juice. Following yam bean root juice ingestion, systemic nitrate apparently converts to nitrite and further to NO which may attenuate platelet responses to collagen stimulation. Cardiovascular benefits of juices from yam bean root and guava fruit are noteworthy in term of the cardiovascular health-promoting approach. Randomized controlled trial TCTR20150228001 .

The Nitrification Inhibitor Methyl 3-(4-Hydroxyphenyl)Propionate Modulates Root Development by Interfering with Auxin Signaling via the NO/ROS Pathway1

PubMed Central

Liu, Yangyang; Wang, Ruling; Zhang, Ping

2016-01-01

Methyl 3-(4-hydroxyphenyl)propionate (MHPP) is a root exudate that functions as a nitrification inhibitor and as a modulator of the root system architecture (RSA) by inhibiting primary root (PR) elongation and promoting lateral root formation. However, the mechanism underlying MHPP-mediated modulation of the RSA remains unclear. Here, we report that MHPP inhibits PR elongation in Arabidopsis (Arabidopsis thaliana) by elevating the levels of auxin expression and signaling. MHPP induces an increase in auxin levels by up-regulating auxin biosynthesis, altering the expression of auxin carriers, and promoting the degradation of the auxin/indole-3-acetic acid family of transcriptional repressors. We found that MHPP-induced nitric oxide (NO) production promoted reactive oxygen species (ROS) accumulation in root tips. Suppressing the accumulation of NO or ROS alleviated the inhibitory effect of MHPP on PR elongation by weakening auxin responses and perception and by affecting meristematic cell division potential. Genetic analysis supported the phenotype described above. Taken together, our results indicate that MHPP modulates RSA remodeling via the NO/ROS-mediated auxin response pathway in Arabidopsis. Our study also revealed that MHPP significantly induced the accumulation of glucosinolates in roots, suggesting the diverse functions of MHPP in modulating plant growth, development, and stress tolerance in plants. PMID:27217493

The inhibiting effects of Urtica dioica root extracts on experimentally induced prostatic hyperplasia in the mouse.

PubMed

Lichius, J J; Muth, C

1997-08-01

Extracts of stinging nettle roots (Urtica dioica L. Urticaceae) are used in the treatment of benign prostatic hyperplasia (BPH). We established a BPH-model by directly implanting an urogenital sinus (UGS) into the ventral prostate gland of an adult mouse. Five differently prepared stinging nettle root extracts were tested in this model. The 20% methanolic extract was the most effective with a 51.4% inhibition of induced growth.

Shoot phytochrome B modulates reactive oxygen species homeostasis in roots via abscisic acid signaling in Arabidopsis.

PubMed

Ha, Jun-Ho; Kim, Ju-Heon; Kim, Sang-Gyu; Sim, Hee-Jung; Lee, Gisuk; Halitschke, Rayko; Baldwin, Ian T; Kim, Jeong-Il; Park, Chung-Mo

2018-06-01

Underground roots normally reside in darkness. However, they are often exposed to ambient light that penetrates through cracks in the soil layers which can occur due to wind, heavy rain or temperature extremes. In response to light exposure, roots produce reactive oxygen species (ROS) which promote root growth. It is known that ROS-induced growth promotion facilitates rapid escape of the roots from non-natural light. Meanwhile, long-term exposure of the roots to light elicits a ROS burst, which causes oxidative damage to cellular components, necessitating that cellular levels of ROS should be tightly regulated in the roots. Here we demonstrate that the red/far-red light photoreceptor phytochrome B (phyB) stimulates the biosynthesis of abscisic acid (ABA) in the shoots, and notably the shoot-derived ABA signals induce a peroxidase-mediated ROS detoxification reaction in the roots. Accordingly, while ROS accumulate in the roots of the phyb mutant that exhibits reduced primary root growth in the light, such an accumulation of ROS did not occur in the dark-grown phyb roots that exhibited normal growth. These observations indicate that mobile shoot-to-root ABA signaling links shoot phyB-mediated light perception with root ROS homeostasis to help roots adapt to unfavorable light exposure. We propose that ABA-mediated shoot-to-root phyB signaling contributes to the synchronization of shoot and root growth for optimal propagation and performance in plants. © 2018 The Authors The Plant Journal © 2018 John Wiley & Sons Ltd.

NaCl regulation of plasma membrane H(+)-ATPase gene expression in a glycophyte and a halophyte.

PubMed

Niu, X; Narasimhan, M L; Salzman, R A; Bressan, R A; Hasegawa, P M

1993-11-01

NaCl regulation of plasma membrane H(+)-ATPase gene expression in the glycophyte tobacco (Nicotiana tabacum L. var Wisconsin 38) and the halophyte Atriplex nummularia L. was evaluated by comparison of organ-specific mRNA abundance using homologous cDNA probes encoding the ATPases of the respective plants. Accumulation of mRNA was induced by NaCl in fully expanded leaves and in roots but not in expanding leaves or stems. The NaCl responsiveness of the halophyte to accumulate plasma membrane H(+)-ATPase mRNA in roots was substantially greater than that of the glycophyte. Salt-induced transcript accumulation in A. nummularia roots was localized by in situ hybridization predominantly to the elongation zone, but mRNA levels also increased in the zone of differentiation. Increased message accumulation in A. nummularia roots could be detected within 8 h after NaCl (400 mM) treatment, and maximal levels were severalfold greater than in roots of untreated control plants. NaCl-induced plasma membrane H(+)-ATPase gene expression in expanded leaves and roots presumably indicates that these organs require increased H(+)-electrochemical potential gradients for the maintenance of plant ion homeostasis for salt adaptation. The greater capacity of the halophyte to induce plasma membrane H(+)-ATPase gene expression in response to NaCl may be a salt-tolerance determinant.

NaCl regulation of plasma membrane H(+)-ATPase gene expression in a glycophyte and a halophyte.

PubMed Central

Niu, X; Narasimhan, M L; Salzman, R A; Bressan, R A; Hasegawa, P M

1993-01-01

NaCl regulation of plasma membrane H(+)-ATPase gene expression in the glycophyte tobacco (Nicotiana tabacum L. var Wisconsin 38) and the halophyte Atriplex nummularia L. was evaluated by comparison of organ-specific mRNA abundance using homologous cDNA probes encoding the ATPases of the respective plants. Accumulation of mRNA was induced by NaCl in fully expanded leaves and in roots but not in expanding leaves or stems. The NaCl responsiveness of the halophyte to accumulate plasma membrane H(+)-ATPase mRNA in roots was substantially greater than that of the glycophyte. Salt-induced transcript accumulation in A. nummularia roots was localized by in situ hybridization predominantly to the elongation zone, but mRNA levels also increased in the zone of differentiation. Increased message accumulation in A. nummularia roots could be detected within 8 h after NaCl (400 mM) treatment, and maximal levels were severalfold greater than in roots of untreated control plants. NaCl-induced plasma membrane H(+)-ATPase gene expression in expanded leaves and roots presumably indicates that these organs require increased H(+)-electrochemical potential gradients for the maintenance of plant ion homeostasis for salt adaptation. The greater capacity of the halophyte to induce plasma membrane H(+)-ATPase gene expression in response to NaCl may be a salt-tolerance determinant. PMID:8022933

The Separability of Morphological Processes from Semantic Meaning and Syntactic Class in Production of Single Words: Evidence from the Hebrew Root Morpheme.

PubMed

Deutsch, Avital

2016-02-01

In the present study we investigated to what extent the morphological facilitation effect induced by the derivational root morpheme in Hebrew is independent of semantic meaning and grammatical information of the part of speech involved. Using the picture-word interference paradigm with auditorily presented distractors, Experiment 1 compared the facilitation effect induced by semantically transparent versus semantically opaque morphologically related distractor words (i.e., a shared root) on the production latency of bare nouns. The results revealed almost the same amount of facilitation for both relatedness conditions. These findings accord with the results of the few studies that have addressed this issue in production in Indo-European languages, as well as previous studies in written word perception in Hebrew. Experiment 2 compared the root's facilitation effect, induced by morphologically related nominal versus verbal distractors, on the production latency of bare nouns. The results revealed a facilitation effect of similar size induced by the shared root, regardless of the distractor's part of speech. It is suggested that the principle that governs lexical organization at the level of morphology, at least for Hebrew roots, is form-driven and independent of semantic meaning. This principle of organization crosses the linguistic domains of production and written word perception, as well as grammatical organization according to part of speech.

Expression of animal anti-apoptotic gene Ced-9 enhances tolerance during Glycine max L.-Bradyrhizobium japonicum interaction under saline stress but reduces nodule formation.

PubMed

Robert, Germán; Muñoz, Nacira; Melchiorre, Mariana; Sánchez, Federico; Lascano, Ramiro

2014-01-01

The mechanisms by which the expression of animal cell death suppressors in economically important plants conferred enhanced stress tolerance are not fully understood. In the present work, the effect of expression of animal antiapoptotic gene Ced-9 in soybean hairy roots was evaluated under root hairs and hairy roots death-inducing stress conditions given by i) Bradyrhizobium japonicum inoculation in presence of 50 mM NaCl, and ii) severe salt stress (150 mM NaCl), for 30 min and 3 h, respectively. We have determined that root hairs death induced by inoculation in presence of 50 mM NaCl showed characteristics of ordered process, with increased ROS generation, MDA and ATP levels, whereas the cell death induced by 150 mM NaCl treatment showed non-ordered or necrotic-like characteristics. The expression of Ced-9 inhibited or at least delayed root hairs death under these treatments. Hairy roots expressing Ced-9 had better homeostasis maintenance, preventing potassium release; increasing the ATP levels and controlling the oxidative damage avoiding the increase of reactive oxygen species production. Even when our results demonstrate a positive effect of animal cell death suppressors in plant cell ionic and redox homeostasis under cell death-inducing conditions, its expression, contrary to expectations, drastically inhibited nodule formation even under control conditions.

Effects of diabetes on tooth movement and root resorption after orthodontic force application in rats.

PubMed

Arita, K; Hotokezaka, H; Hashimoto, M; Nakano-Tajima, T; Kurohama, T; Kondo, T; Darendeliler, M A; Yoshida, N

2016-05-01

To investigate the effects of diabetes on orthodontic tooth movement and orthodontically induced root resorption in rats. Twenty-three 10-week-old male Sprague-Dawley rats divided into control (n = 7), diabetes (n = 9), and diabetes + insulin (n = 7) groups. Diabetes was induced by administering a single intraperitoneal injection of streptozotocin. Rats with a blood glucose level exceeding 250 mg/dl were assigned to the diabetes group. Insulin was administered daily to the diabetes + insulin group. A nickel-titanium closed-coil spring of 10 g was applied for 2 weeks to the maxillary left first molar in all rats to induce mesial tooth movement. Tooth movement was measured using microcomputed tomography images. To determine the quantity of root resorption, the mesial surfaces of the mesial and distal roots of the first molar were analyzed using both scanning electron microscopy and scanning laser microscopy. After 2 weeks, the amount of tooth movement in the diabetic rats was lower than that in the control rats. Root resorption was also significantly lower in the diabetic rats. These responses of the rats caused by diabetes were mostly diminished by insulin administration. Diabetes significantly reduced orthodontic tooth movement and orthodontically induced root resorption in rats. The regulation of blood glucose level through insulin administration largely reduced these abnormal responses to orthodontic force application. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Systemic and local regulation of phosphate and nitrogen transporter genes by arbuscular mycorrhizal fungi in roots of winter wheat (Triticum aestivum L.).

PubMed

Duan, Jianfeng; Tian, Hui; Drijber, Rhae A; Gao, Yajun

2015-11-01

Previous studies have reported that the expression of phosphate (Pi) or nitrogen (N) transporter genes in roots of plants could be regulated by arbuscular mycorrhizal (AM) fungi, but little is known whether the regulation is systemic or not. The present study investigated the systemic and local regulation of multiple phosphate and nitrogen transporter genes by four AM fungal species belonging to four genera in the roots of winter wheat. A split-root culture system with AM inoculated (MR) and non-inoculated root compartments (NR) was used to investigate the systemic or local responses of phosphate and nitrogen transporter genes to colonization by four AM fungi in the roots of wheat. The expression of four Pi transporter, five nitrate transporter, and three ammonium transporter genes was quantified using real-time PCR. Of the four AM fungi tested, all locally increased expression of the AM-inducible Pi transporter genes, and most locally decreased expression of a Pi-starvation inducible Pi transporter gene. The addition of N in soil increased the expression of either Pi starvation inducible Pi transporters or AM inducible Pi transporters. Inoculation with AM fungi either had no effect, or could locally or systemically down-regulate expression of nitrogen transporter genes depending on gene type and AM fungal species. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Ionospheric vertical plasma drift perturbations due to the quasi 2 day wave

NASA Astrophysics Data System (ADS)

Gu, Sheng-Yang; Liu, Han-Li; Li, Tao; Dou, Xiankang

2015-05-01

The thermosphere-ionosphere-mesosphere-electrodynamics-general circulation model is utilized to study the vertical E × B drift perturbations due to the westward quasi 2 day wave with zonal wave numbers 2 and 3 (W2 and W3). The simulations show that both wind components contribute directly and significantly to the vertical drift, which is not merely confined to low latitudes. The vertical drifts at the equator induced by the total wind perturbations of W2 are comparable with that at middle latitudes, while the vertical drifts from W3 are much stronger at middle latitudes than at the equator. The ion drift perturbations induced by the zonal and meridional wind perturbations of W2 are nearly in-phase with each other, whereas the phase discrepancies of the ion drift induced by the individual wind component of W3 are much larger. This is because the wind perturbations of W2 and W3 have different latitudinal structures and phases, which result in different ionospheric responses through wind dynamo.

Agrobacterium rhizogenes-mediated DNA transfer to Aesculus hippocastanum L. and the regeneration of transformed plants.

PubMed

Zdravković-Korać, S; Muhovski, Y; Druart, P; Calić, D; Radojević, L

2004-04-01

Hairy roots were induced from androgenic embryos of horse chestnut (Aesculus hippocastanum L.) by infection with Agrobacterium rhizogenes strain A4GUS. Single roots were selected according to their morphology in the absence of antibiotic or herbicide resistance markers. Seventy-one putative transformed hairy root lines from independent transformation events were established. Regeneration was induced in MS liquid medium supplemented with 30 microM 6-benzylaminopurine (BA), and the regenerants were multiplied on MS solid medium containing 10 microM BA. Following elongation on MS medium supplemented with 1 microM BA and 500 mg/l polyvinylpyrrolidone, the shoots were subjected to a root-inducing treatment. Stable integration of TL-DNA within the horse chestnut genome was confirmed by Southern hybridization. The copy number of transgenes was estimated to be from two to four.

Root growth and physiology of potted and field-grown trembling aspen exposed to tropospheric ozone

Treesearch

M.D. Coleman; R.E. Dickson; J.G. Isebrands; D.F. Karnosky

1996-01-01

We studied root growth and respiration of potted plants and field-grown aspen trees (Populus tremuloides Michx.) exposed to ambient or twice-ambient ozone. Root dry weight of potted plants decreased up to 45% after 12 weeks of ozone treatment, and root system respiration decreased by 27%. The ozone-induced decrease in root system respiration of...

Halogenated auxins affect microtubules and root elongation in Lactuca sativa

NASA Technical Reports Server (NTRS)

Zhang, N.; Hasenstein, K. H.

2000-01-01

We studied the effect of 4,4,4-trifluoro-3-(indole-3-)butyric acid (TFIBA), a recently described root growth stimulator, and 5,6-dichloro-indole-3-acetic acid (DCIAA) on growth and microtubule (MT) organization in roots of Lactuca sativa L. DCIAA and indole-3-butyric acid (IBA) inhibited root elongation and depolymerized MTs in the cortex of the elongation zone, inhibited the elongation of stele cells, and promoted xylem maturation. Both auxins caused the plane of cell division to shift from anticlinal to periclinal. In contrast, TFIBA (100 micromolar) promoted elongation of primary roots by 40% and stimulated the elongation of lateral roots, even in the presence of IBA, the microtubular inhibitors oryzalin and taxol, or the auxin transport inhibitor naphthylphthalamic acid. However, TFIBA inhibited the formation of lateral root primordia. Immunostaining showed that TFIBA stabilized MTs orientation perpendicular to the root axis, doubled the cortical cell length, but delayed xylem maturation. The data indicate that the auxin-induced inhibition of elongation and swelling of roots results from reoriented phragmoplasts, the destabilization of MTs in elongating cells, and promotion of vessel formation. In contrast, TFIBA induced promotion of root elongation by enhancing cell length, prolonging transverse MT orientation, delaying cell and xylem maturation.

Root Adaptive Responses to Aluminum-Treatment Revealed by RNA-Seq in Two Citrus Species With Different Aluminum-Tolerance

PubMed Central

Guo, Peng; Qi, Yi-Ping; Yang, Lin-Tong; Lai, Ning-Wei; Ye, Xin; Yang, Yi; Chen, Li-Song

2017-01-01

Seedlings of aluminum (Al)-tolerant Citrus sinensis and Al-intolerant Citrus grandis were fertigated daily with nutrient solution containing 0 and 1.0 mM AlCl3●6H2O for 18 weeks. The Al-induced decreases of biomass and root total soluble proteins only occurred in C. grandis, demonstrating that C. sinensis had higher Al-tolerance than C. grandis. Under Al-treatment, C. sinensis roots secreted more citrate and malate than C. grandis ones; less Al was accumulated in C. sinenis than in C. grandis leaves. The Al-induced reduction of phosphorus was lesser in C. sinensis roots and leaves than in C. grandis ones, whereas the Al-induced increase of sulfur was greater in C. sinensis roots and leaves. Using RNA-seq, we isolated 1905 and 2670 differentially expressed genes (DEGs) from Al-treated C. sinensis than C. grandis roots, respectively. Among these DEGs, only 649 DEGs were shared by the two species. Further analysis suggested that the following several aspects conferred C. sinensis higher Al-tolerance: (a) Al-treated C. sinensis seedlings had a higher external Al detoxification capacity via enhanced Al-induced secretion of organic acid anions, a higher antioxidant capacity and a more efficient chelation system in roots; (b) Al-treated C. sinensis seedlings displayed a higher level of sulfur in roots and leaves possibly due to increased uptake and decreased export of sulfur and a higher capacity to maintain the cellular phosphorus homeostasis by enhancing phosphorus acquisition and utilization; (c) Cell wall and cytoskeleton metabolism, energy and carbohydrate metabolism and signal transduction displayed higher adaptative responses to Al in C. sinensis than in C. grandis roots; (d) More upregulated than downregulated genes related to fatty acid and amino acid metabolisms were isolated from Al-treated C. sinensis roots, but the reverse was the case for Al-treated C. grandis roots. These results provide a platform for further investigating the roles of genes possibly responsible for citrus Al-tolerance. PMID:28337215

Evaluation of the Root and Canal Morphology of Maxillary Permanent Molars and the Incidence of the Second Mesiobuccal Root Canal in Greek Population Using Cone-beam Computed Tomography

PubMed Central

Nikoloudaki, Georgia E.; Kontogiannis, Taxiarchis G.; Kerezoudis, Nikolaos P.

2015-01-01

Objectives: Cone-Beam Computed Tomography is an alternative imaging technique which has been recently introduced in the field of Oral & Maxillofacial Radiology. It has rapidly gained great popularity among clinicians due to its ability to detect lesions and defects of the orofacial region and provide three-dimensional information about them. In the field of Endodontics, CBCT can be a useful tool to reveal tooth morphology irregularities, additional root canals and vertical root fractures. The objective of this study is to evaluate the root and root canal morphology of the maxillary permanent molars in Greek population using Cone-Beam Computed Tomography. Materials and Methods : 273 cone-beam computed tomography (CBCT) images were examined. The number of roots and root canals of the first and second maxillary molars were evaluated. Root canal configuration was classified according to Weine’s classification by two independent examiners and statistical analysis was performed. Results : A total of 812 molars (410 first and 402 second ones) were evaluated. The vast majority of both first and second molars had three roots (89.26% and 85.07%, respectively). Most first molars had four canals, while most second molars had three. In the mesiobuccal roots, one foramen was recorded in 80.91% of all teeth. Other rare morphologic variations were also found, such as fusion of a maxillary second molar with a supernumerary tooth. Conclusion : Within the limitations of this study, it can be concluded that more attention should be given to the detection of additional canals during root canal treatment in maxillary permanent molars. Towards this effort, CBCT can provide the clinician with supplemental information about the different root canal configurations for successful Root Canal Treatment. PMID:26464594

Quantitative, nondestructive estimates of coarse root biomass in a temperate pine forest using 3-D ground-penetrating radar (GPR)

NASA Astrophysics Data System (ADS)

Molon, Michelle; Boyce, Joseph I.; Arain, M. Altaf

2017-01-01

Coarse root biomass was estimated in a temperate pine forest using high-resolution (1 GHz) 3-D ground-penetrating radar (GPR). GPR survey grids were acquired across a 400 m2 area with varying line spacing (12.5 and 25 cm). Root volume and biomass were estimated directly from the 3-D radar volume by using isometric surfaces calculated with the marching cubes algorithm. Empirical relations between GPR reflection amplitude and root diameter were determined for 14 root segments (0.1-10 cm diameter) reburied in a 6 m2 experimental test plot and surveyed at 5-25 cm line spacing under dry and wet soil conditions. Reburied roots >1.4 cm diameter were detectable as continuous root structures with 5 cm line separation. Reflection amplitudes were strongly controlled by soil moisture and decreased by 40% with a twofold increase in soil moisture. GPR line intervals of 12.5 and 25 cm produced discontinuous mapping of roots, and GPR coarse root biomass estimates (0.92 kgC m-2) were lower than those obtained previously with a site-specific allometric equation due to nondetection of vertical roots and roots <1.5 cm diameter. The results show that coarse root volume and biomass can be estimated directly from interpolated 3-D GPR volumes by using a marching cubes approach, but mapping of roots as continuous structures requires high inline sampling and line density (<5 cm). The results demonstrate that 3-D GPR is viable approach for estimating belowground carbon and for mapping tree root architecture. This methodology can be applied more broadly in other disciplines (e.g., archaeology and civil engineering) for imaging buried structures.

Posterior root tear of the medial and lateral meniscus.

PubMed

Petersen, Wolf; Forkel, Philipp; Feucht, Matthias J; Zantop, Thore; Imhoff, Andreas B; Brucker, Peter U

2014-02-01

An avulsion of the tibial insertion of the meniscus or a radial tear close to the meniscal insertion is defined as a root tear. In clinical practice, the incidence of these lesions is often underestimated. However, several biomechanical studies have shown that the effect of a root tear is comparable to a total meniscectomy. Clinical studies documented progredient arthritic changes following root tears, thereby supporting basic science studies. The clinical diagnosis is limited by unspecific symptoms. In addition to the diagnostic arthroscopy, MRI is considered to be the gold standard of diagnosis of a meniscal root tear. Three different direct MRI signs for the diagnosis of a meniscus root tear have been described: Radial linear defect in the axial plane, vertical linear defect (truncation sign) in the coronal plane, and the so-called ghost meniscus sign in the sagittal plane. Meniscal extrusion is also considered to be an indirect sign of a root tear, but is less common in lateral root tears. During arthroscopy, the function of the meniscus root must be assessed by probing. However, visualization of the meniscal insertions is challenging. Refixation of the meniscal root can be performed using a transtibial pull-out suture, suture anchors, or side-to-side repair. Several short-term studies reported good clinical results after medial or lateral root repair. Nevertheless, MRI and second-look arthroscopy revealed high rates of incomplete or absent healing, especially for medial root tears. To date, most studies are case series with short-term follow-up and level IV evidence. Outerbridge grade 3 or 4 chondral lesions and varus malalignment of >5° were found to predict an inferior clinical outcome after medial meniscus root repair. Further research is needed to evaluate long-term results and to define evident criteria for meniscal root repair.

Cardenolides, induced responses, and interactions between above- and belowground herbivores of milkweed (Asclepias spp.).

PubMed

Rasmann, Sergio; Agrawal, Anurag A; Cook, Susan C; Erwin, Alexis C

2009-09-01

Theory has long predicted allocation patterns for plant defense against herbivory, but only recently have both above- and belowground plant defenses been considered simultaneously. Milkweeds in the genus Asclepias are a classic chemically defended clade of plants with toxic cardenolides (cardiac glycosides) and pressurized latex employed as anti-herbivore weapons. Here we combine a comparative approach to investigate broadscale patterns in allocation to root vs. shoot defenses across species with a species-specific experimental approach to identify the consequences of defense allocational shifts on a specialist herbivore. Our results show phylogenetic conservatism for inducibility of shoot cardenolides by an aboveground herbivore, with only four closely related tropical species showing significant induction; the eight temperate species examined were not inducible. Allocation to root and shoot cardenolides was positively correlated across species, and this relationship was maintained after accounting for phylogenetic nonindependence. In contrast to long-standing theoretical predictions, we found no evidence for a trade-off between constitutive and induced cardenolides; indeed the two were positively correlated across species in both roots and shoots. Finally, specialist root and shoot herbivores of common milkweed (A. syriaca) had opposing effects on latex production, and these effects had consequences for caterpillar growth consistent with latex providing resistance. Although cardenolides were not affected by our treatments, A. syriaca allocated 40% more cardenolides to shoots over roots. We conclude that constitutive and inducible defenses are not trading off across plant species, and shoots of Asclepias are more inducible than roots. Phylogenetic conservatism cannot explain the observed patterns of cardenolide levels across species, but inducibility per se was conserved in a tropical clade. Finally, given that above- and belowground herbivores can systemically alter the defensive phenotype of plants, we concur with recent calls for a whole-plant perspective in testing models of plant defense allocation.

Load redistribution in walking and trotting Beagles with induced forelimb lameness.

PubMed

Abdelhadi, Jalal; Wefstaedt, Patrick; Galindo-Zamora, Vladimir; Anders, Alexandra; Nolte, Ingo; Schilling, Nadja

2013-01-01

To evaluate the load redistribution mechanisms in walking and trotting dogs with induced forelimb lameness. 7 healthy adult Beagles. Dogs walked and trotted on an instrumented treadmill to determine control values for peak and mean vertical force as well as vertical impulse for all 4 limbs. A small sphere was attached to the ventral pad of the right forelimb paw to induce a reversible lameness, and recordings were repeated for both gaits. Additionally, footfall patterns were assessed to test for changes in temporal gait variables. During walking and trotting, peak and mean vertical force as well as vertical impulse were decreased in the ipsilateral forelimb, increased in the contralateral hind limb, and remained unchanged in the ipsilateral hind limb after lameness was induced. All 3 variables were increased in the contralateral forelimb during trotting, whereas only mean vertical force and vertical impulse were increased during walking. Stance phase duration increased in the contralateral forelimb and hind limb during walking but not during trotting. Analysis of the results suggested that compensatory load redistribution mechanisms in dogs depend on the gait. All 4 limbs should be evaluated in basic research and clinical studies to determine the effects of lameness on the entire body. Further studies are necessary to elucidate specific mechanisms for unloading of the affected limb and to determine the long-term effects of load changes in animals with chronic lameness.

ABNORMAL INFLORESCENCE MERISTEM1 Functions in Salicylic Acid Biosynthesis to Maintain Proper Reactive Oxygen Species Levels for Root Meristem Activity in Rice

PubMed Central

Zhao, Hongyu; Ruan, Wenyuan; Deng, Minjuan; Wang, Fang; Peng, Jinrong; Luo, Jie; Chen, Zhixiang

2017-01-01

Root meristem activity determines root growth and root architecture and consequently affects water and nutrient uptake in plants. However, our knowledge about the regulation of root meristem activity in crop plants is very limited. Here, we report the isolation and characterization of a short root mutant in rice (Oryza sativa) with reduced root meristem activity. This root growth defect is caused by a mutation in ABNORMAL INFLORESCENCE MERISTEM1 (AIM1), which encodes a 3-hydroxyacyl-CoA dehydrogenase, an enzyme involved in β-oxidation. The reduced root meristem activity of aim1 results from reduced salicylic acid (SA) levels and can be rescued by SA application. Furthermore, reduced SA levels are associated with reduced levels of reactive oxygen species (ROS) in aim1, likely due to increased expression of redox and ROS-scavenging-related genes, whose increased expression is (at least in part) caused by reduced expression of the SA-inducible transcriptional repressors WRKY62 and WRKY76. Like SA, ROS application substantially increased root length and root meristem activity in aim1. These results suggest that AIM1 is required for root growth in rice due to its critical role in SA biosynthesis: SA maintains root meristem activity through promoting ROS accumulation by inducing the activity of WRKY transcriptional repressors, which repress the expression of redox and ROS-scavenging genes. PMID:28298519

Coarse root topology of Norway spruce (Picea abies) and its effects on slope stability

NASA Astrophysics Data System (ADS)

Lith, Aniek; Schmaltz, Elmar; Bogaard, Thom; Keesstra, Saskia

2017-04-01

The structural distribution of coarse roots and its beneficial effects on soil reinforcement has widely been assessed. However, it is still not fully understood how topological features of coarse roots (e.g. branching patterns) are affected by slope inclination and further influence the ability of young trees to reinforce soil. This study aims to analyse empirically the impact of slope gradient on the topological development of coarse roots and thus to assess its effects on soil reinforcement. We performed root system excavations on two young Picea abies: tree A on a gently inclined plane (β ≈ 12°) where slope failures are not expected; tree B on a slope (β ≈ 35°) with failure potential. The diameter (d) of the segments between distinct root nodes (root ends, branching locations, direction changes and attachments to stem) of coarse roots (d > 2mm) were measured in situ. The spatial coordinates (x,y,z) of the nodes and surface were measured on a plane raster grid, from which segment length (ls), direction and inclination towards the surface (βr) were derived. Roots and segments were classified into laterals (βr < 10°), obliques (10° ≤ βr < 70°) and verticals (βr ≥ 70°), with βr,max = 90°. We assigned topological orders to the segments according to developmental (DSC) and functional segment classifications (FSC), to obtain quantitative relations between the topological order and number of segments, total and average ls. The maximal root cohesion (cr) of each segment was assessed using material specific tensile forces (Tr), root area ratio (RAR) and βr, assuming that a potential slip surface would cross the root system parallel to the slope. Laterals depicted the majority of roots (57 %) for tree A orientated rather in upslope direction (76.8 %), whereas tree B showed mostly obliques (54 %) orientated rather in downslope direction (55.4 %). Vertical roots were scarcely observable for both trees. DSC showed a high r2 (> 0.84) for the segments and ls. FSC showed high r2 (> 0.95) for the number of segments and the total length. RAR values of tree B are distributed rather upslope (76.8 % of RARtot), compared to 44.5 % of RARtot for tree A. The average cr (0.15) of each segment of tree B was remarkably higher than of tree A (0.10), leading to the conclusion that the slope has a strong influence on cr itself. This is supported by comparing the distribution of cr for both trees, where tree B tends to produce a higher cr in upslope direction (68.7 % of total cr) than tree A (37.7 %). In contrast to our expectations, tree B shows generally a higher cr compared to tree A, despite lower subsurface biomass. The findings indicate that the distinct branching patterns of coarse roots might determine the distribution of the RAR and thus lead to a higher reinforcement potential of young Picea abies on slopes.

Light Requirement for Shoot Regeneration in Horseradish Hairy Roots 1

PubMed Central

Saitou, Tsutomu; Kamada, Hiroshi; Harada, Hiroshi

1992-01-01

Hairy roots of horseradish (Armoracia rusticana) were induced by inoculation with Agrobacterium rhizogenes harboring Ri plasmid and cultured on phytohormone-free Murashige and Skoog medium after eliminating the bacteria. Hairy roots grew vigorously and sometimes formed yellowish calli under dark conditions. On the other hand, growth of hairy roots stopped after several weeks of culture with light, then shoots were regenerated. Frequency of shoot formation from hairy roots increased as the culture period in light lengthened and the light intensity increased. The shoot regeneration was induced by treatment with white or red light, but not with far-red light. Shoot regeneration by red light was inhibited by following treatment with far-red light. Red and far-red light reversibly affected shoot regeneration. Excised roots of nontransformed plants grew quite slowly on phytohormone-free Murashige and Skoog medium and occasionally formed shoots under white light conditions. PMID:16669041

Light requirement for shoot regeneration in horseradish hairy roots.

PubMed

Saitou, T; Kamada, H; Harada, H

1992-08-01

Hairy roots of horseradish (Armoracia rusticana) were induced by inoculation with Agrobacterium rhizogenes harboring Ri plasmid and cultured on phytohormone-free Murashige and Skoog medium after eliminating the bacteria. Hairy roots grew vigorously and sometimes formed yellowish calli under dark conditions. On the other hand, growth of hairy roots stopped after several weeks of culture with light, then shoots were regenerated. Frequency of shoot formation from hairy roots increased as the culture period in light lengthened and the light intensity increased. The shoot regeneration was induced by treatment with white or red light, but not with far-red light. Shoot regeneration by red light was inhibited by following treatment with far-red light. Red and far-red light reversibly affected shoot regeneration. Excised roots of nontransformed plants grew quite slowly on phytohormone-free Murashige and Skoog medium and occasionally formed shoots under white light conditions.

Functional Tooth Restoration by Allogeneic Mesenchymal Stem Cell-Based Bio-Root Regeneration in Swine

PubMed Central

Wei, Fulan; Song, Tieli; Ding, Gang; Xu, Junji; Liu, Yi; Liu, Dayong; Fan, Zhipeng; Zhang, Chunmei

2013-01-01

Our previous proof-of-concept study showed the feasibility of regenerating the dental stem cell-based bioengineered tooth root (bio-root) structure in a large animal model. Here, we used allogeneic dental mesenchymal stem cells to regenerate bio-root, and then installed a crown on the bio-root to restore tooth function. A root shape hydroxyapatite tricalcium phosphate scaffold containing dental pulp stem cells was covered by a Vc-induced periodontal ligament stem cell sheet and implanted into a newly generated jaw bone implant socket. Six months after implantation, a prefabricated porcelain crown was cemented to the implant and subjected to tooth function. Clinical, radiological, histological, ultrastructural, systemic immunological evaluations and mechanical properties were analyzed for dynamic changes in the bio-root structure. The regenerated bio-root exhibited characteristics of a normal tooth after 6 months of use, including dentinal tubule-like and functional periodontal ligament-like structures. No immunological response to the bio-roots was observed. We developed a standard stem cell procedure for bio-root regeneration to restore adult tooth function. This study is the first to successfully regenerate a functional bio-root structure for artificial crown restoration by using allogeneic dental stem cells and Vc-induced cell sheet, and assess the recipient immune response in a preclinical model. PMID:23363023

Horizontal stresses induced by vertical processes in planetary lithospheres

NASA Technical Reports Server (NTRS)

Banerdt, W. B.

1993-01-01

Understanding the state of stress in the elastic lithosphere is of fundamental importance for planetary geophysics, as it is the link between the observed geologic structures on the surface and the processes which form and modify these structures. As such, it can provide valuable constraints for the difficult problem of determining interior structure and processes. On the Earth, most large scale, organized deformation can be related to lateral tectonics associated with plate dynamics; however, the tectonics on many extraterrestrial bodies (such as the Moon, Mars, and most of the outer-planet satellites) appears to be primarily vertical in nature, and the horizontal stresses induced by vertical motions and loads are expected to dominate the deformation of their lithospheres. The largest stress contributions from vertical loading come from the flexure of the lithosphere, which induces both bending moments and membrane stresses. We are concerned here only with nonflexural changes in the state of stress induced by processes such as sedimentary and volcanic deposition, erosional denudation, and changes in the thermal gradient that induce uplift or subsidence. This analysis is important both for evaluating stresses for specific regions in which the vertical stress history can be estimated, as well as for applying the proper loading conditions to global stress models. It is also of interest for providing a reference state of stress for interpreting stress measurements in the crust of the Earth.

Vertical accretion and shallow subsidence in a mangrove forest of southwestern Florida, U.S.A

USGS Publications Warehouse

Cahoon, D.R.; Lynch, J.C.

1997-01-01

Simultaneous measurements of vertical accretion from artificial soil marker horizons and soil elevation change from sedimentation-erosion table (SET) plots were used to evaluate the processes related to soil building in range, basin, and overwash mangrove forests located in a low-energy lagoon which recieves minor inputs of terregenous sediments. Vertical accretion measures reflect the contribution of surficial sedimentation (sediment deposition and surface root growth). Measures of elevation change reflect not only the contributions of vertical accretion but also those of subsurface processes such as compaction, decomposition and shrink-swell. The two measures were used to calculate amounts of shallow subsidence (accretion minus elevation change) in each mangrove forest. The three forest types represent different accretionary envrionments. The basin forest was located behind a natural berm. Hydroperiod here was controlled primarily by rainfall rather than tidal exchange, although the basin flooded during extreme tidal events. Soil accretion here occurred primarily by autochthonous organic matter inputs, and elevation was controlled by accretion and shrink-swell of the substrate apparently related to cycles of flooding-drying and/or root growth-decomposition. This hydrologically-restricted forest did not experience an accretion or elevation deficit relative to sea-level rise. The tidally dominated fringe and overwash island forests accreted through mineral sediment inputs bound in place by plant roots. Filamentous turf algae played an important role in stabilizing loose muds in the fringe forest where erosion was prevalent. Elevation in these high-energy environments was controlled not only by accretion but also by erosion and/or shallow subsidence. The rate of shallow subsidence was consistently 3-4 mm y-1 in the fringe and overwash island forests but was negligible in the basin forest. Hence, the vertical development of mangrove soils was influenced by both surface and subsurface processes and the procces controlling soil elevation differed among forest types. The mangrove ecosystem at Rookery Bay has remained stable as sea level has risen during the past 70 years. Yet, lead-210 accretion data suggest a substantial accretion deficit has occurred in the past century (accretion was 10-20 cm < sea-level rise from 1930 to 1990) in the fringe and island forests at Rookery Bay. In contrast, our measures of elevation change mostly equalled the estimates of sea-level rise and shallow subsidence. These data suggest that (1) vertical accretion in this system is driven by local sea-level rise and shallow subsidence, and (2) the mangrove forests are mostly keeping pace with sea-level rise. Thus, the vulnerability of this mangrove ecosystem to sea-level rise is best described in terms of an elevation deficit (elevation change minus sea-level rise) based on annual measures rather than an accretion deficit (accretion minus sea-level rise) based on decadal measures.

Clonal variation in lateral and basal rooting of Populus irrigated with landfill leachate

Treesearch

R.S. Zalesny Jr.; J.A. Zalesny

2011-01-01

Successful establishment and productivity of Populus depends upon adventitious rooting from: 1) lateral roots that develop from either preformed or induced primordia and 2) basal roots that differentiate from callus at the base of the cutting in response to wounding. Information is needed for phytotechnologies about the degree to which ...

First Assessment of Carbon Stock in the Belowground Biomass of Brazilian Mangroves.

PubMed

Santos, Daniel M C; Estrada, Gustavo C D; Fernandez, Viviane; Estevam, Marciel R M; Souza, Brunna T DE; Soares, Mário L G

2017-01-01

Studies on belowground roots biomass have increasingly reported the importance of the contribution of this compartment in carbon stock maintenance in mangrove forests. To date, there are no estimates of this contribution in Brazilian mangrove forests, although the country has the second largest area of mangroves worldwide. For this study, trenches dug in fringing forests in Guaratiba State Biological Reserve (Rio de Janeiro, Brazil) were used to evaluate the contribution of the different classes of roots and the vertical stratification of carbon stock. The total carbon stock average in belowground roots biomass in these forests was 104.41 ± 20.73 tC.ha-1. From that, an average of 84.13 ± 21.34 tC.ha-1 corresponded to the carbon stock only in fine roots, which have diameters smaller than 5 mm and are responsible for over 80% of the total belowground biomass. Most of the belowground carbon stock is concentrated in the first 40 cm below the surface (about 70%). The root:shoot ratio in this study is 1.14. These estimates demonstrate that the belowground roots biomass significantly contributes, more than 50%, to the carbon stock in mangrove forests. And the mangrove root biomass can be greater than that of other Brazilian ecosystems.

Glucose and phytohormone interplay in controlling root directional growth in Arabidopsis.

PubMed

Singh, Manjul; Gupta, Aditi; Laxmi, Ashverya

2014-01-01

Sensing and responding toward gravity vector is a complicated and multistep process. Gravity is a constant factor feeding plants with reliable information for the spatial orientation of their organs. Auxin, cytokinin, ethylene and BRs have been the most explored hormones in relation to gravitropism. We have previously shown that glucose (Glc) could promote brassinosteroid (BR) signaling thereby inducing changes in root directional growth. Auxin signaling and polar transport components are also involved in Glc induced changes in root directional growth. Here, we provide evidence for involvement of cytokinin and ethylene signaling components in regulation of root directional growth downstream to Glc and BR. Altogether, Glc mediated change in root direction is an adaptive feature which is a result of a collaborative effort integrating phytohormonal signaling cues.

Root Antioxidant Mechanisms in Relation to Root Thermotolerance in Perennial Grass Species Contrasting in Heat Tolerance

PubMed Central

Xu, Yi; Burgess, Patrick; Huang, Bingru

2015-01-01

Mechanisms of plant root tolerance to high temperatures through antioxidant defense are not well understood. The objective of this study was to investigate whether superior root thermotolerance of heat-tolerant Agrostis scabra relative to its congeneric heat-sensitive Agrostis stolonifera was associated with differential accumulation of reactive oxygen species and antioxidant scavenging systems. A. scabra ‘NTAS’ and A. stolonifera ‘Penncross’ plants were exposed to heat stress (35/30°C, day/night) in growth chambers for 24 d. Superoxide (O2 -) content increased in both A. stolonifera and A. scabra roots under heat stress but to a far lesser extent in A. scabra than in A. stolonifera. Hydrogen peroxide (H2O2) content increased significantly in A. stolonifera roots but not in A. scabra roots responding to heat stress. The content of antioxidant compounds (ascorbate and glutathione) did not differ between A. stolonifera and A. scabra under heat stress. Enzymatic activity of superoxide dismutase was less suppressed in A. scabra than that in A. stolonifera under heat stress, while peroxidase and catalase were more induced in A. scabra than in A. stolonifera. Similarly, their encoded transcript levels were either less suppressed, or more induced in A. scabra roots than those in A. stolonifera during heat stress. Roots of A. scabra exhibited greater alternative respiration rate and lower cytochrome respiration rate under heat stress, which was associated with suppression of O2 - and H2O2 production as shown by respiration inhibitors. Superior root thermotolerance of A. scabra was related to decreases in H2O2 and O2 - accumulation facilitated by active enzymatic antioxidant defense systems and the maintenance of alternative respiration, alleviating cellular damages by heat-induced oxidative stress. PMID:26382960

Root Antioxidant Mechanisms in Relation to Root Thermotolerance in Perennial Grass Species Contrasting in Heat Tolerance.

PubMed

Xu, Yi; Burgess, Patrick; Huang, Bingru

2015-01-01

Mechanisms of plant root tolerance to high temperatures through antioxidant defense are not well understood. The objective of this study was to investigate whether superior root thermotolerance of heat-tolerant Agrostis scabra relative to its congeneric heat-sensitive Agrostis stolonifera was associated with differential accumulation of reactive oxygen species and antioxidant scavenging systems. A. scabra 'NTAS' and A. stolonifera 'Penncross' plants were exposed to heat stress (35/30°C, day/night) in growth chambers for 24 d. Superoxide (O2(-)) content increased in both A. stolonifera and A. scabra roots under heat stress but to a far lesser extent in A. scabra than in A. stolonifera. Hydrogen peroxide (H2O2) content increased significantly in A. stolonifera roots but not in A. scabra roots responding to heat stress. The content of antioxidant compounds (ascorbate and glutathione) did not differ between A. stolonifera and A. scabra under heat stress. Enzymatic activity of superoxide dismutase was less suppressed in A. scabra than that in A. stolonifera under heat stress, while peroxidase and catalase were more induced in A. scabra than in A. stolonifera. Similarly, their encoded transcript levels were either less suppressed, or more induced in A. scabra roots than those in A. stolonifera during heat stress. Roots of A. scabra exhibited greater alternative respiration rate and lower cytochrome respiration rate under heat stress, which was associated with suppression of O2(-) and H2O2 production as shown by respiration inhibitors. Superior root thermotolerance of A. scabra was related to decreases in H2O2 and O2(-) accumulation facilitated by active enzymatic antioxidant defense systems and the maintenance of alternative respiration, alleviating cellular damages by heat-induced oxidative stress.

SIZ1 Regulation of Phosphate Starvation-Induced Root Architecture Remodeling Involves the Control of Auxin Accumulation1[C][W][OA

PubMed Central

Miura, Kenji; Lee, Jiyoung; Gong, Qingqiu; Ma, Shisong; Jin, Jing Bo; Yoo, Chan Yul; Miura, Tomoko; Sato, Aiko; Bohnert, Hans J.; Hasegawa, Paul M.

2011-01-01

Phosphate (Pi) limitation causes plants to modulate the architecture of their root systems to facilitate the acquisition of Pi. Previously, we reported that the Arabidopsis (Arabidopsis thaliana) SUMO E3 ligase SIZ1 regulates root architecture remodeling in response to Pi limitation; namely, the siz1 mutations cause the inhibition of primary root (PR) elongation and the promotion of lateral root (LR) formation. Here, we present evidence that SIZ1 is involved in the negative regulation of auxin patterning to modulate root system architecture in response to Pi starvation. The siz1 mutations caused greater PR growth inhibition and LR development of seedlings in response to Pi limitation. Similar root phenotypes occurred if Pi-deficient wild-type seedlings were supplemented with auxin. N-1-Naphthylphthalamic acid, an inhibitor of auxin efflux activity, reduced the Pi starvation-induced LR root formation of siz1 seedlings to a level equivalent to that seen in the wild type. Monitoring of the auxin-responsive reporter DR5::uidA indicated that auxin accumulates in PR tips at early stages of the Pi starvation response. Subsequently, DR5::uidA expression was observed in the LR primordia, which was associated with LR elongation. The time-sequential patterning of DR5::uidA expression occurred earlier in the roots of siz1 as compared with the wild type. In addition, microarray analysis revealed that several other auxin-responsive genes, including genes involved in cell wall loosening and biosynthesis, were up-regulated in siz1 relative to wild-type seedlings in response to Pi starvation. Together, these results suggest that SIZ1 negatively regulates Pi starvation-induced root architecture remodeling through the control of auxin patterning. PMID:21156857

Endodontic management of C-shaped root canal system of mandibular first molar by using a modified technique of self-adjusting file system.

PubMed

Helvacioglu-Yigit, Dilek

2015-01-01

C-shaped canal system is a seldom-found root canal anatomy which displays a challenge in all stages of endodontic treatment. According to the literature, this type of canal morphology is not a common finding in the mandibular first molar teeth. This case report presents endodontic management of a mandibular first molar with a C-shaped canal system. Root canal system was cleaned and shaped by nickel-titanium (NiTi) rotary instruments combined with self-adjusting file (SAF). Obturation was performed using warm, vertical condensation combined with the injection of warm gutta-percha. Follow-up examination 12 months later showed that the tooth was asymptomatic. The radiological findings presented no signs of periapical pathology. The clinician must be aware of the occurence and complexity of C-shaped canals in mandibular first molar teeth to perform a successful root canal treatment. The supplementary use of SAF after application of rotary instruments in C-shaped root canals might be a promising approach in endodontic treatment of this type of canal morphology.

AOX1-Subfamily Gene Members in Olea europaea cv. “Galega Vulgar”—Gene Characterization and Expression of Transcripts during IBA-Induced in Vitro Adventitious Rooting

PubMed Central

Lousa, Diana; M. Soares, Cláudio; Santos Macedo, Elisete; Arnholdt-Schmitt, Birgit

2018-01-01

Propagation of some Olea europaea L. cultivars is strongly limited due to recalcitrant behavior in adventitious root formation by semi-hardwood cuttings. One example is the cultivar ”Galega vulgar”. The formation of adventitious roots is considered a morphological response to stress. Alternative oxidase (AOX) is the terminal oxidase of the alternative pathway of the plant mitochondrial electron transport chain. This enzyme is well known to be induced in response to several biotic and abiotic stress situations. This work aimed to characterize the alternative oxidase 1 (AOX1)-subfamily in olive and to analyze the expression of transcripts during the indole-3-butyric acid (IBA)-induced in vitro adventitious rooting (AR) process. OeAOX1a (acc. no. MF410318) and OeAOX1d (acc. no. MF410319) were identified, as well as different transcript variants for both genes which resulted from alternative polyadenylation events. A correlation between transcript accumulation of both OeAOX1a and OeAOX1d transcripts and the three distinct phases (induction, initiation, and expression) of the AR process in olive was observed. Olive AOX1 genes seem to be associated with the induction and development of adventitious roots in IBA-treated explants. A better understanding of the molecular mechanisms underlying the stimulus needed for the induction of adventitious roots may help to develop more targeted and effective rooting induction protocols in order to improve the rooting ability of difficult-to-root cultivars. PMID:29462998

MPK6 controls H2 O2-induced root elongation by mediating Ca2+ influx across the plasma membrane of root cells in Arabidopsis seedlings.

PubMed

Han, Shuan; Fang, Lin; Ren, Xuejian; Wang, Wenle; Jiang, Jing

2015-01-01

Mitogen-activated protein kinases (MPKs) play critical roles in signalling and growth, and Ca(2+) and H2 O2 control plant growth processes associated with abscisic acid (ABA). However, it remains unclear how MPKs are involved in H2 O2 - and Ca(2+) -mediated root elongation. Root elongation in seedlings of the loss-of-function mutant Atmpk6 (Arabidopsis thaliana MPK6) was less sensitive to moderate H2 O2 or ABA than that in wild-type (WT) plants. The enhanced elongation was a result of root cell expansion. This effect disappeared when ABA-induced H2 O2 accumulation or the cytosolic Ca(2+) increase were defective. Molecular and biochemical evidence showed that increased expression of the cell wall peroxidase PRX34 in Atmpk6 root cells enhanced apoplastic H2 O2 generation; this promoted a cytosolic Ca(2+) increase and Ca(2+) influx across the plasma membrane. The plasma membrane damage caused by high levels of H2 O2 was ameliorated in a Ca(2+) -dependent manner. These results suggested that there was intensified PRX34-mediated H2 O2 generation in the apoplast and increased Ca(2+) flux into the cytosol of Atmpk6 root cells; that is, the spatial separation of apoplastic H2 O2 from cytosolic Ca(2+) in root cells prevented H2 O2 -induced inhibition of root elongation in Atmpk6 seedlings. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

Root-derived auxin contributes to the phosphorus-deficiency-induced cluster-root formation in white lupin (Lupinus albus).

PubMed

Meng, Zhi Bin; You, Xue Di; Suo, Dong; Chen, Yun Long; Tang, Caixian; Yang, Jian Li; Zheng, Shao Jian

2013-08-01

Formation of cluster roots is a typical morphological response to phosphorus (P) deficiency in white lupin (Lupinus albus), but its physiological and molecular mechanisms are still unclear. We investigated the role of auxin in the initiation of cluster roots by distinguishing the sources of auxin, measuring the longitudinal distribution patterns of free indole-3-acetic acid (IAA) along the root and the related gene expressions responsible for polar auxin transport (PAT) in different developmental stages of cluster roots. We found that removal of shoot apex or primary root apex and application of auxin-influx or -efflux transport inhibitors, 3-chloro-4-hydroxyphenylacetic acid, N-1-naphthylphthalamic acid and 2,3,5-triiodobenzoic acid, to the stem did not affect the number of cluster roots and the free-IAA concentration in the roots of P-deficient plants, but when these inhibitors were applied directly to the growth media, the cluster-root formation was greatly suppressed, suggesting the fundamental role of root-derived IAA in cluster-root formation. The concentration of free IAA in the roots was higher in P-deficient plants than in P-adequate ones, and the highest in the lateral-root apex and the lowest in the mature cluster roots. Meanwhile the expression patterns of LaAUX1, LaPIN1 and LaPIN3 transcripts related to PAT was consistent with concentrations of free IAA along the lateral root, indicating the contribution of IAA redistribution in the cluster-root development. We proposed that root-derived IAA plays a direct and important role in the P-deficiency-induced formation of cluster roots. Copyright © Physiologia Plantarum 2012.

Methane emissions to the atmosphere through aquatic plants

NASA Technical Reports Server (NTRS)

Sebacher, D. I.; Harriss, R. C.; Bartlett, K. B.

1985-01-01

The movement of methane (CH4) from anaerobic sediments through the leaves, stems, and flowers of aquatic plants and into the atmosphere was found to provide a significant pathway for the emission of CH4 from the aquatic substrates of flooded wetlands. Methane concentrations well above the surrounding ambient air levels were found in the mesophyll of 16 varies of aquatic plants and are attributed to transpiration, diffusion, and pressure-induced flow of gaseous CH4 from the roots when they are embedded in CH4-saturated anaerobic sediments. Methane emissions from the emergent parts of aquatic plants were measured using floating chamber techniques and by enclosing the plants in polyethylene bags of known volume. Concentration changes were monitored in the trapped air using syringes and gas chromatographic techniques. Vertical profiles of dissolved CH4 in sediment pore water surrounding the aquatic plants' rhizomes were obtained using an interstitial sampling technique. Methane emissions from the aquatic plants studied varied from 14.8 mg CH4/d to levels too low to be detectable. Rooted and unrooted freshwater aquatic plants were studied as well as saltwater and brackish water plants. Included in the experiment is detailed set of measurements on CH4 emissions from the common cattail (Typha latifolia). This paper illustrates that aquatic plants play an important gas exchange role in the C cycle between wetlands and the atmosphere.

Separating the roles of acropetal and basipetal auxin transport on gravitropism with mutations in two Arabidopsis multidrug resistance-like ABC transporter genes.

PubMed

Lewis, Daniel R; Miller, Nathan D; Splitt, Bessie L; Wu, Guosheng; Spalding, Edgar P

2007-06-01

Two Arabidopsis thaliana ABC transporter genes linked to auxin transport by various previous results were studied in a reverse-genetic fashion. Mutations in Multidrug Resistance-Like1 (MDR1) reduced acropetal auxin transport in roots by 80% without affecting basipetal transport. Conversely, mutations in MDR4 blocked 50% of basipetal transport without affecting acropetal transport. Developmental and auxin distribution phenotypes associated with these altered auxin flows were studied with a high-resolution morphometric system and confocal microscopy, respectively. Vertically grown mdr1 roots produced positive and negative curvatures threefold greater than the wild type, possibly due to abnormal auxin distribution observed in the elongation zone. However, upon 90 degrees reorientation, mdr1 gravitropism was inseparable from the wild type. Thus, acropetal auxin transport maintains straight growth but contributes surprisingly little to gravitropism. Conversely, vertically maintained mdr4 roots grew as straight as the wild type, but their gravitropism was enhanced. Upon reorientation, curvature in this mutant developed faster, was distributed more basally, and produced a greater total angle than the wild type. An amplified auxin asymmetry may explain the mdr4 hypertropism. Double mutant analysis indicated that the two auxin transport streams are more independent than interdependent. The hypothesis that flavanols regulate MDR-dependent auxin transport was supported by the epistatic relationship of mdr4 to the tt4 phenylpropanoid pathway mutation.

Nitrogen fluxes through unsaturated zones in five agricultural settings across the USA

NASA Astrophysics Data System (ADS)

Green, C. T.; Fisher, L. H.; Bekins, B. A.

2006-12-01

The main controls on nitrogen (N) fluxes between the root zone and the water table were determined for agricultural sites in California, Washington, Nebraska, Indiana, and Maryland in 2004 and 2005. Sites included irrigated and non-irrigated fields; soil textures ranging from clay to sand; crops including corn, soybeans, almonds, and pasture; and unsaturated zone thicknesses ranging from 0.5 to 20 m. Chemical analyses of water from lysimeters, shallow wells, and sediment cores indicate that advective transport of nitrate is the dominant process affecting the rate of N transport below the root zone. Vertical profiles of (1) N species, (2) stable N and O isotopes, and (3) oxygen gas in unsaturated zone air and shallow ground water, and correlations between N and other agricultural chemicals indicate that reactions do not greatly affect N concentrations between the root zone and the capillary fringe. Relatively stable concentrations at depths greater than a few meters allow calculation of nitrogen fluxes to the saturated zone. These fluxes are equivalent to 14 - 64% of the N application rates. At the same locations, median vertical fluxes of N in ground water are generally lower, ranging from 4 - 37% of N application rates. The lower nitrate fluxes in ground water reflect processes including lateral flow to tile drains and denitrification in the capillary fringe, as well as historical changes in N inputs.

Nitrate induction of root hair density is mediated by TGA1/TGA4 and CPC transcription factors in Arabidopsis thaliana.

PubMed

Canales, Javier; Contreras-López, Orlando; Álvarez, José M; Gutiérrez, Rodrigo A

2017-10-01

Root hairs are specialized cells that are important for nutrient uptake. It is well established that nutrients such as phosphate have a great influence on root hair development in many plant species. Here we investigated the role of nitrate on root hair development at a physiological and molecular level. We showed that nitrate increases root hair density in Arabidopsis thaliana. We found that two different root hair defective mutants have significantly less nitrate than wild-type plants, suggesting that in A. thaliana root hairs have an important role in the capacity to acquire nitrate. Nitrate reductase-null mutants exhibited nitrate-dependent root hair phenotypes comparable with wild-type plants, indicating that nitrate is the signal that leads to increased formation of root hairs. We examined the role of two key regulators of root hair cell fate, CPC and WER, in response to nitrate treatments. Phenotypic analyses of these mutants showed that CPC is essential for nitrate-induced responses of root hair development. Moreover, we showed that NRT1.1 and TGA1/TGA4 are required for pathways that induce root hair development by suppression of longitudinal elongation of trichoblast cells in response to nitrate treatments. Our results prompted a model where nitrate signaling via TGA1/TGA4 directly regulates the CPC root hair cell fate specification gene to increase formation of root hairs in A. thaliana. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

Nitric oxide is involved in the oxytetracycline-induced suppression of root growth through inhibiting hydrogen peroxide accumulation in the root meristem

NASA Astrophysics Data System (ADS)

Yu, Qing-Xiang; Ahammed, Golam Jalal; Zhou, Yan-Hong; Shi, Kai; Zhou, Jie; Yu, Yunlong; Yu, Jing-Quan; Xia, Xiao-Jian

2017-02-01

Use of antibiotic-contaminated manure in crop production poses a severe threat to soil and plant health. However, few studies have studied the mechanism by which plant development is affected by antibiotics. Here, we used microscopy, flow cytometry, gene expression analysis and fluorescent dyes to study the effects of oxytetracycline (OTC), a widely used antibiotic in agriculture, on root meristem activity and the accumulation of hydrogen peroxide (H2O2) and nitric oxide (NO) in the root tips of tomato seedlings. We found that OTC caused cell cycle arrest, decreased the size of root meristem and inhibited root growth. Interestingly, the inhibition of root growth by OTC was associated with a decline in H2O2 levels but an increase in NO levels in the root tips. Diphenyliodonium (DPI), an inhibitor of H2O2 production, showed similar effects on root growth as those of OTC. However, exogenous H2O2 partially reversed the effects on the cell cycle, meristem size and root growth. Importantly, cPTIO (the NO scavenger) and tungstate (an inhibitor of nitrate reductase) significantly increased H2O2 levels in the root tips and reversed the inhibition of root growth by OTC. Out results suggest that OTC-induced NO production inhibits H2O2 accumulation in the root tips, thus leading to cell cycle arrest and suppression of root growth.

[Effects of Ca2+ on nitric oxide-induced adventitious rooting in cucumber under drought stress].

PubMed

Li, Chun Lan; Niu, Li Juan; Hu, Lin Li; Liao, Wei Biao; Chen, Yue

2017-11-01

Cucumber (Cucumis sativus L. 'Xinchun 4') was used to explore the relationship between nitric oxide (NO) and calcium (Ca 2+ ) during adventitious rooting under drought stress. Rooting parameters, endogenous Ca 2+ fluorescent intensity and the antioxidant enzymes activity (SOD, CAT and APX) in cucumber explants under drought stress were investigated. The results showed that treatment with 200 μmol·L -1 CaCl 2 and 0.05% PEG significantly improved the number and length of adventitious root in cucumber explants under drought stress, while the application of Ca 2+ chelating agent (EGTA) and channel inhibitor (BAPTA/AM) significantly decreased NO-induced number and length of adventitious root under drought stress. Under drought stress, the fluorescence intensity of Ca 2+ in hypocotyls treated with NO and CaCl 2 was improved, however, the Ca 2+ fluorescence intensity in the hypocotyls treated with NO scavenger (cPTIO) was significantly lower than that in the hypocotyls treated with NO. Under drought stress, the activities of antioxidant enzymes in the cucumber explants were significantly promoted by the treatments with NO and CaCl 2 , however, Ca 2+ chelating agent and channel inhibitor significantly decreased the activity of antioxidant enzymes induced by NO. In conclusion, Ca 2+ might be involved in the process of NO-adjusted antioxidant enzymes activity during adventitious rooting under drought stress, which alleviated the negative effects of drought on the adventitious rooting and promoted the formation of adventitious roots.

The signal transducer NPH3 integrates the phototropin1 photosensor with PIN2-based polar auxin transport in Arabidopsis root phototropism.

PubMed

Wan, Yinglang; Jasik, Jan; Wang, Li; Hao, Huaiqing; Volkmann, Dieter; Menzel, Diedrik; Mancuso, Stefano; Baluška, František; Lin, Jinxing

2012-02-01

Under blue light (BL) illumination, Arabidopsis thaliana roots grow away from the light source, showing a negative phototropic response. However, the mechanism of root phototropism is still unclear. Using a noninvasive microelectrode system, we showed that the BL sensor phototropin1 (phot1), the signal transducer NONPHOTOTROPIC HYPOCOTYL3 (NPH3), and the auxin efflux transporter PIN2 were essential for BL-induced auxin flux in the root apex transition zone. We also found that PIN2-green fluorescent protein (GFP) localized to vacuole-like compartments (VLCs) in dark-grown root epidermal and cortical cells, and phot1/NPH3 mediated a BL-initiated pathway that caused PIN2 redistribution to the plasma membrane. When dark-grown roots were exposed to brefeldin A (BFA), PIN2-GFP remained in VLCs in darkness, and BL caused PIN2-GFP disappearance from VLCs and induced PIN2-GFP-FM4-64 colocalization within enlarged compartments. In the nph3 mutant, both dark and BL BFA treatments caused the disappearance of PIN2-GFP from VLCs. However, in the phot1 mutant, PIN2-GFP remained within VLCs under both dark and BL BFA treatments, suggesting that phot1 and NPH3 play different roles in PIN2 localization. In conclusion, BL-induced root phototropism is based on the phot1/NPH3 signaling pathway, which stimulates the shootward auxin flux by modifying the subcellular targeting of PIN2 in the root apex transition zone.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cohen, Michael F.; Gurung, Sushma; Birarda, Giovanni

In the genus Azolla rapid abscission of roots from floating fronds occurs within minutes in response to a variety of stresses, including exposure to nitrite. We found that hydrogen peroxide, though itself not an inducer of root abscission, modulates nitrite-induced root abscission by Azolla pinnata in a dose-dependent manner, with 2 mM H 2O 2 significantly diminishing the responsiveness to 2 mM NaNO 2, and 10 mM H 2O 2 slightly enhancing it. Hypoxia, which has been found in other plants to result in autogenic production of H 2O 2, dramatically stimulated root abscission of A. pinnata in response tomore » nitrite, especially for plants previously cultivated in medium containing 5 mM KNO 3 compared to plants cultivated under N 2-fixing conditions without combined nitrogen. Plants, including Azolla, produce the small signaling molecule nitric oxide (NO) from nitrite using nitrate reductase. We found Azolla plants to display dose-dependent root abscission in response to the NO donor spermine NONOate. Treatment of plants with the thiol-modifying agents S-methyl methanethiosulfonate or glutathione inhibited the nitrite-induced root abscission response. Synchrotron radiation-based Fourier transform infrared spectromicroscopy revealed higher levels of carbonylation in the abscission zone of dropped roots, indicative of reaction products of polysaccharides with potent free radical oxidants. Lastly, we hypothesize that metabolic products of nitrite and NO react with H 2O 2 in the apoplast leading to free-radical-mediated cleavage of structural polysaccharides and consequent rapid root abscission.« less

Analysis of changes in relative elemental growth rate patterns in the elongation zone of Arabidopsis roots upon gravistimulation

NASA Technical Reports Server (NTRS)

Mullen, J. L.; Ishikawa, H.; Evans, M. L.

1998-01-01

Although Arabidopsis is an important system for studying root physiology, the localized growth patterns of its roots have not been well defined, particularly during tropic responses. In order to characterize growth rate profiles along the apex of primary roots of Arabidopsis thaliana (L.) Heynh (ecotype Columbia) we applied small charcoal particles to the root surface and analyzed their displacement during growth using an automated video digitizer system with custom software for tracking the markers. When growing vertically, the maximum elongation rate occurred 481 +/- 50 microns back from the extreme tip of the root (tip of root cap), and the elongation zone extended back to 912 +/- 137 microns. The distal elongation zone (DEZ) has previously been described as the apical region of the elongation zone in which the relative elemental growth rate (REGR) is < or = 30% of the peak rate in the central elongation zone. By this definition, our data indicate that the basal limit of the DEZ was located 248 +/- 30 microns from the root tip. However, after gravistimulation, the growth patterns of the root changed. Within the first hour of graviresponse, the basal limit of the DEZ and the position of peak REGR shifted apically on the upper flank of the root. This was due to a combination of increased growth in the DEZ and growth inhibition in the central elongation zone. On the lower flank, the basal limit of the DEZ shifted basipetally as the REGR decreased. These factors set up the gradient of growth rate across the root, which drives curvature.

Physiological minimum temperatures for root growth in seven common European broad-leaved tree species.

PubMed

Schenker, Gabriela; Lenz, Armando; Körner, Christian; Hoch, Günter

2014-03-01

Temperature is the most important factor driving the cold edge distribution limit of temperate trees. Here, we identified the minimum temperatures for root growth in seven broad-leaved tree species, compared them with the species' natural elevational limits and identified morphological changes in roots produced near their physiological cold limit. Seedlings were exposed to a vertical soil-temperature gradient from 20 to 2 °C along the rooting zone for 18 weeks. In all species, the bulk of roots was produced at temperatures above 5 °C. However, the absolute minimum temperatures for root growth differed among species between 2.3 and 4.2 °C, with those species that reach their natural distribution limits at higher elevations also tending to have lower thermal limits for root tissue formation. In all investigated species, the roots produced at temperatures close to the thermal limit were pale, thick, unbranched and of reduced mechanical strength. Across species, the specific root length (m g(-1) root) was reduced by, on average, 60% at temperatures below 7 °C. A significant correlation of minimum temperatures for root growth with the natural high elevation limits of the investigated species indicates species-specific thermal requirements for basic physiological processes. Although these limits are not necessarily directly causative for the upper distribution limit of a species, they seem to belong to a syndrome of adaptive processes for life at low temperatures. The anatomical changes at the cold limit likely hint at the mechanisms impeding meristematic activity at low temperatures.

Involvement of nitric oxide in the jasmonate-dependent basal defense against root-knot nematode in tomato plants.

PubMed

Zhou, Jie; Jia, Feifei; Shao, Shujun; Zhang, Huan; Li, Guiping; Xia, Xiaojian; Zhou, Yanhong; Yu, Jingquan; Shi, Kai

2015-01-01

Jasmonic acid (JA) and nitric oxide (NO) are well-characterized signaling molecules in plant defense responses. However, their roles in plant defense against root-knot nematode (RKN, Meloidogyne incognita) infection are largely unknown. In this study, we found that the transcript levels of the JA- and NO-related biosynthetic and signaling component genes were induced after RKN infection. Application of exogenous JA and sodium nitroprusside (SNP; a NO donor) significantly decreased the number of egg masses in tomato roots after RKN infection and partially alleviated RKN-induced decreases in plant fresh weight and net photosynthetic rate. These molecules also alleviated RKN-induced increases in root electrolyte leakage and membrane peroxidation. Importantly, NO scavenger partially inhibited JA-induced RKN defense. The pharmacological inhibition of JA biosynthesis significantly increased the plants' susceptibility to RKNs, which was effectively alleviated by SNP application, showing that NO may be involved in the JA-dependent RKN defense pathway. Furthermore, both JA and SNP induced increases in protease inhibitor 2 (PI2) gene expression after RKN infestation. Silencing of PI2 compromised both JA- and SNP-induced RKN defense responses, suggesting that the PI2 gene mediates JA- and NO-induced defense against RKNs. This work will be important for deepening the understanding of the mechanisms involved in basal defense against RKN attack in plants.

Involvement of nitric oxide in the jasmonate-dependent basal defense against root-knot nematode in tomato plants

PubMed Central

Zhou, Jie; Jia, Feifei; Shao, Shujun; Zhang, Huan; Li, Guiping; Xia, Xiaojian; Zhou, Yanhong; Yu, Jingquan; Shi, Kai

2015-01-01

Jasmonic acid (JA) and nitric oxide (NO) are well-characterized signaling molecules in plant defense responses. However, their roles in plant defense against root-knot nematode (RKN, Meloidogyne incognita) infection are largely unknown. In this study, we found that the transcript levels of the JA- and NO-related biosynthetic and signaling component genes were induced after RKN infection. Application of exogenous JA and sodium nitroprusside (SNP; a NO donor) significantly decreased the number of egg masses in tomato roots after RKN infection and partially alleviated RKN-induced decreases in plant fresh weight and net photosynthetic rate. These molecules also alleviated RKN-induced increases in root electrolyte leakage and membrane peroxidation. Importantly, NO scavenger partially inhibited JA-induced RKN defense. The pharmacological inhibition of JA biosynthesis significantly increased the plants’ susceptibility to RKNs, which was effectively alleviated by SNP application, showing that NO may be involved in the JA-dependent RKN defense pathway. Furthermore, both JA and SNP induced increases in protease inhibitor 2 (PI2) gene expression after RKN infestation. Silencing of PI2 compromised both JA- and SNP-induced RKN defense responses, suggesting that the PI2 gene mediates JA- and NO-induced defense against RKNs. This work will be important for deepening the understanding of the mechanisms involved in basal defense against RKN attack in plants. PMID:25914698

Effect of microcystins on root growth, oxidative response, and exudation of rice (Oryza sativa).

PubMed

Cao, Qing; Rediske, Richard R; Yao, Lei; Xie, Liqiang

2018-03-01

A 30 days indoor hydroponic experiment was carried out to evaluate the effect of microcystins (MCs) on rice root morphology and exudation, as well as bioaccumulation of MCs in rice. MCs were bioaccumulated in rice with the greatest concentrations being observed in the leaves (113.68μgg -1 Fresh weight (FW)) when exposed to 500μgL -1 MCs. Root activity at 500μgL -1 decreased 37%, compared to the control. MCs also induced disruption of the antioxidant system and lipid peroxidation in rice roots. Root growth was significantly inhibited by MCs. Root weight, length; surface area and volume were significantly decreased, as well as crown root number and lateral root number. After 30 days exposure to MCs, an increase was found in tartaric acid and malic acid while the other organic acids were not affected. Glycine, tyrosine, and glutamate were the only amino acids stimulated at MCs concentrations of 500μgL -1 . Similarly, dissolved organic carbon (DOC) and carbohydrate at 50 and 500μgL -1 treatments were significantly increased. The increase of DOC and carbohydrate in root exudates was due to rice root membrane permeability changes induced by MCs. Overall, this study indicated that MCs significantly inhibited rice root growth and affected root exudation. Copyright © 2017 Elsevier Inc. All rights reserved.

Optimization of Tube Current in Cone-beam Computed Tomography for the Detection of Vertical Root Fractures with Different Intracanal Materials.

PubMed

Gaêta-Araujo, Hugo; Silva de Souza, Gabriela Queiroz; Freitas, Deborah Queiroz; de Oliveira-Santos, Christiano

2017-10-01

There is no consensus about the accuracy of cone-beam computed tomography (CBCT) for detecting vertical root fractures (VRFs), nor is there certainty about the isolated effect of different tube current parameters on the diagnosis of VRF through CBCT scans. This study aimed to evaluate how tube current affects the detection of VRF on CBCT examinations in the absence of intracanal materials and in the presence of gutta-percha (GP) and metal (MP) or fiberglass (FP) intracanal posts. The sample consisted of 320 CBCT scans of tooth roots with and without VRF divided into 8 groups: no fracture/no intracanal material; no fracture + GP; no fracture + MP; no fracture + FP; fracture/no intracanal material; fracture + GP; fracture + MP; fracture + FP. The scans were acquired with an OP300 unit using 4 different milliamperes (4 mA, 8 mA, 10 mA, 13 mA). Five oral radiologists analyzed the images. The area under the receiver operating characteristic curve (Az), sensitivity, specificity, positive and negative predictive values, and interobserver agreement were calculated. Diagnostic performance for the different milliamperes tested was similar for teeth without root filling materials or with FP. Teeth with GP and MP showed the highest Az values for 8 mA and 10 mA, respectively. For teeth with MP, specificity was significantly higher when 10 mA was used. For teeth without root filling materials or with FP, the use of a reduced milliampere does not seem to influence the detection of VRF in a significant manner. For teeth with GP and MP, an increased milliampere may lead to increased diagnostic performance. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Pullout failure strength of the posterior horn of the medial meniscus with root ligament tear.

PubMed

Kim, Young-Mo; Joo, Yong-Bum

2013-07-01

To evaluate the reparability of the posterior horn of the medial meniscus with root ligament tear by measuring the actual pullout failure strength of a simple vertical suture of an arthroscopic subtotal meniscectomized posterior horn of the medial meniscus. From November 2009 to May 2010, nine posterior horns of the medial meniscus specimens were collected from arthroscopic subtotal meniscectomy performed as a treatment for root ligament rupture of the posterior horn of the medial meniscus. Simple vertical sutures were performed on the specimens, and pullout failure load was tested with a biaxial servohydraulic testing machine (Model 8874; Instron Corp., Norwood, MA, USA). The degree of degeneration, extrusion, and medial displacement of the medial meniscus were evaluated with magnetic resonance imaging (MRI). The Kellgren-Lawrence classification was used in standing plain radiography, and mechanical alignment was measured using orthoroentgenography. Tear morphology was classified into ligament proper type or meniscoligamentous junctional type according to the site of the torn root ligament of the posterior horn of the medial meniscus during arthroscopy. The mean pullout failure strength of the posterior horn of the medial meniscus was 71.6 ± 23.2 N (range, 41.4-107.7 N). The degree of degeneration of the posterior horn of the medial meniscus on MRI showed statistically significant correlation with pullout failure strength and Kellgren-Lawrence classification. Pullout failure strength showed correlation with mechanical alignment and Kellgren-Lawrence classification (P < 0.05). The measurement of pullout failure strength of the posterior horn of the medial meniscus with root ligament tear showed a degree of repairability. The degree of degeneration of the posterior horn of the medial meniscus on MRI showed a significant correlation with the pullout failure strength. The pullout failure strength was also not only correlated with the degree of degeneration of the posterior horn of the medial meniscus, but also with mechanical alignment and Kellgren-Lawrence classification, which represent bony degenerative change.

Laser-induced local activation of Mg-doped GaN with a high lateral resolution for high power vertical devices

NASA Astrophysics Data System (ADS)

Kurose, Noriko; Matsumoto, Kota; Yamada, Fumihiko; Roffi, Teuku Muhammad; Kamiya, Itaru; Iwata, Naotaka; Aoyagi, Yoshinobu

2018-01-01

A method for laser-induced local p-type activation of an as-grown Mg-doped GaN sample with a high lateral resolution is developed for realizing high power vertical devices for the first time. As-grown Mg-doped GaN is converted to p-type GaN in a confined local area. The transition from an insulating to a p-type area is realized to take place within about 1-2 μm fine resolution. The results show that the technique can be applied in fabricating the devices such as vertical field effect transistors, vertical bipolar transistors and vertical Schottkey diode so on with a current confinement region using a p-type carrier-blocking layer formed by this technique.

The interactive impact of root branch order and soil genetic horizon on root respiration and nitrogen concentration.

PubMed

Trocha, Lidia K; Bulaj, Bartosz; Kutczynska, Paulina; Mucha, Joanna; Rutkowski, Pawel; Zadworny, Marcin

2017-08-01

In general, respiration (RS) is highly correlated with nitrogen concentration (N) in plant organs, including roots, which exhibit a positive N-RS relationship. Less is known, however, about the relationship between N and RS in roots of different branch orders within an individual tree along a vertical soil profile; this is especially true in trees with contrasting life strategies, such as pioneer Scots pine (Pinus sylvestris L.) vs mid-successional sessile oak (Quercus petraea Liebl.). In the present research, the impact of root branch order, as represented by those with absorptive vs transporting ability, and soil genetic horizon on root N, RS and the N-RS relationship was examined. Mean RS and total N concentration differed significantly among root branch orders and was significantly higher in absorptive roots than in transporting roots. The soil genetic horizon differentially affected root RS in Scots pine vs sessile oak. The genetic horizon mostly affected RS in absorptive roots of Scots pine and transporting roots in sessile oak. Root N was the highest in absorptive roots and most affected by soil genetic horizon in both tree species. Root N was not correlated with soil N, although N levels were higher in roots growing in fertile soil genetic horizons. Overall, RS in different root branch orders was positively correlated with N in both species. The N-RS relationship in roots, pooled by soil genetic horizon, was significant in both species, but was only significant in sessile oak when roots were pooled by root branch order. In both tree species, a significant interaction was found between the soil genetic horizon and root branch order with root function; however, species-specific responses were found. Both root N, which was unaffected by soil N, and the positive N-RS relationship consistently observed in different genetic horizons suggest that root function prevails over environmental factors, such as soil genetic horizon. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Immediate changes in spinal height and pain after aquatic vertical traction in patients with persistent low back symptoms: a crossover clinical trial.

PubMed

Simmerman, Susanne M; Sizer, Phillip S; Dedrick, Gregory S; Apte, Gail G; Brismée, Jean-Michel

2011-05-01

To investigate the effect of aquatic vertical traction on spinal height, pain intensity, and centralization response compared with a land-based supine flexion position for patients with low back pain and signs of nerve root compression. Single-blind, repeated-measures crossover design. Outpatient physical therapy clinic. Ninety-eight subjects were recruited using consecutive sampling, with 28 men and 32 women of a mean ± standard deviation (SD) age of 59.6 ± 11.6 years completing testing. Each subject participated in 2 sessions that consisted of loaded walking for 15 minutes, followed by either 15 minutes of land-based supine position or 15 minutes of aquatic vertical traction. Spinal height change, measured using a commercial stadiometer, was determined after completing loaded walking and after each intervention. The mean ± SD height change of 4.99 ± 2.88 mm after aquatic vertical traction was similar to that of 4.21 ± 2.53 mm after the land-based supine flexion (P = .0969). Paired t-test indicated that both interventions resulted in significant increased height (P < .0001). Decreases in pain after aquatic intervention (2.7 ± 2.1 cm) were significantly greater than decreases after land intervention (1.7 ± 1.7 cm; P = .0034), and centralization of symptoms was more pronounced after aquatic vertical suspension compared with the supine land-based flexion condition (P < .0001). A significant correlation between height change and both pain reduction (r = 0.39; P = .001) and centralization (r = 0.29; P = .013) was observed for the aquatic intervention only. Although both the aquatic and land interventions produced significant increases in overall spinal height, the aquatic intervention produced greater pain relief and centralization response in subjects with low back pain and signs of nerve root compression. Copyright © 2011 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

Tritium Plume Dynamics in the Shallow Unsaturated Zone Adjacent to an Arid Waste Disposal Facility

NASA Astrophysics Data System (ADS)

Maples, S.; Andraski, B. J.; Stonestrom, D. A.; Cooper, C. A.; Michel, R. L.; Pohll, G. M.

2012-12-01

Previous studies at the U.S. Geological Survey's Amargosa Desert Research Site (ADRS) in southern Nevada have documented two plumes of tritiated water-vapor (3HHOg) adjacent to a closed, commercial low-level radioactive waste disposal facility. Wastes were disposed on-site from 1962-92. Tritium has moved long distances (> 400 m) through a shallow (1-2-m depth) dry gravelly layer—orders of magnitude further than anticipated by standard transport models. Geostatistical methods, spatial moment analyses and tritium flux calculations were applied to assess shallow plume dynamics. A grid-based plant-water sampling method was utilized to infer detailed, field-scale 3HHOg concentrations at 5-yr intervals during 2001-11. Results indicate that gravel-layer 3HHOg mass diminished faster than would be expected from radioactive decay (~70% in 10 yr). Both plumes exhibited center-of-mass stability, suggesting that bulk-plume movement is minimal during the period of study. Nonetheless, evidence of localized lateral advancement along some margins, combined with increases in the spatial covariance of concentration distribution, indicates intra-plume mass redistribution is ongoing. Previous studies have recognized that vertical movement of tritiated water from sub-root-zone gravel into the root-zone contributes to atmospheric release via evapotranspiration. Estimates of lateral and vertical tritium fluxes during the study period indicate (1) vertical tritiated water fluxes were dominated by diffusive-vapor fluxes (> 90%), and (2) vertical diffusive-vapor fluxes were roughly an order of magnitude greater than lateral diffusive-vapor fluxes. This behavior highlights the importance of the atmosphere as a tritium sink. Estimates of cumulative vertical diffusive-vapor flux and radioactive decay with time were comparable to observed declines in total shallow plume mass with time. This suggests observed changes in plume mass may (1) be attributed, in considerable part, to these removal mechanisms, and (2) appreciable input from the adjacent disposal facility is not occurring at this time.

Will fluctuations in salt marsh–mangrove dominance alter vulnerability of a subtropical wetland to sea‐level rise?

USGS Publications Warehouse

Mckee, Karen L.; Vervaeke, William

2018-01-01

To avoid submergence during sea-level rise, coastal wetlands build soil surfaces vertically through accumulation of inorganic sediment and organic matter. At climatic boundaries where mangroves are expanding and replacing salt marsh, wetland capacity to respond to sea-level rise may change. To compare how well mangroves and salt marshes accommodate sea-level rise, we conducted a manipulative field experiment in a subtropical plant community in the subsiding Mississippi River Delta. Experimental plots were established in spatially equivalent positions along creek banks in monospecific stands of Spartina alterniflora (smooth cordgrass) or Avicennia germinans (black mangrove) and in mixed stands containing both species. To examine the effect of disturbance on elevation dynamics, vegetation in half of the plots was subjected to freezing (mangrove) or wrack burial (salt marsh), which caused shoot mortality. Vertical soil development was monitored for 6 years with the surface elevation table-marker horizon system. Comparison of land movement with relative sea-level rise showed that this plant community was experiencing an elevation deficit (i.e., sea level was rising faster than the wetland was building vertically) and was relying on elevation capital (i.e., relative position in the tidal frame) to survive. Although Avicennia plots had more elevation capital, suggesting longer survival, than Spartina or mixed plots, vegetation type had no effect on rates of accretion, vertical movement in root and sub-root zones, or net elevation change. Thus, these salt marsh and mangrove assemblages were accreting sediment and building vertically at equivalent rates. Small-scale disturbance of the plant canopy also had no effect on elevation trajectories—contrary to work in peat-forming wetlands showing elevation responses to changes in plant productivity. The findings indicate that in this deltaic setting with strong physical influences controlling elevation (sediment accretion, subsidence), mangrove replacement of salt marsh, with or without disturbance, will not necessarily alter vulnerability to sea-level rise.

Micro-computed tomography analysis of post space preparation in root canals filled with carrier-based thermoplasticized gutta-percha.

PubMed

Schroeder, A A; Ford, N L; Coil, J M

2017-03-01

To determine whether post space preparation deviated from the root canal preparation in canals filled with Thermafil, GuttaCore or warm vertically compacted gutta-percha. Forty-two extracted human permanent maxillary lateral incisors were decoronated, and their root canals instrumented using a standardized protocol. Samples were divided into three groups and filled with Thermafil (Dentsply Tulsa Dental Specialties, Johnson City, TN, USA), GuttaCore (Dentsply Tulsa Dental Specialties) or warm vertically compacted gutta-percha, before post space preparation was performed with a GT Post drill (Dentsply Tulsa Dental Specialties). Teeth were scanned using micro-computed tomography after root filling and again after post space preparation. Scans were examined for number of samples with post space deviation, linear deviation of post space preparation and minimum root thickness before and after post space preparation. Parametric data were analysed with one-way analysis of variance (anova) or one-tailed paired Student's t-tests, whilst nonparametric data were analysed with Fisher's exact test. Deviation occurred in eight of forty-two teeth (19%), seven of fourteen from the Thermafil group (50%), one of fourteen from the GuttaCore group (7%), and none from the gutta-percha group. Deviation occurred significantly more often in the Thermafil group than in each of the other two groups (P < 0.05). Linear deviation of post space preparation was greater in the Thermafil group than in both of the other groups and was significantly greater than that of the gutta-percha group (P < 0.05). Minimum root thickness before post space preparation was significantly greater than it was after post space preparation for all groups (P < 0.01). The differences between the Thermafil, GuttaCore and gutta-percha groups in the number of samples with post space deviation and in linear deviation of post space preparation were associated with the presence or absence of a carrier as well as the different carrier materials. © 2016 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Stereomicroscopic evaluation of dentinal defects induced by new rotary system: “ProTaper NEXT”

PubMed Central

Shori, Deepa Deepak; Shenoi, Pratima Ramakrishna; Baig, Arshia R; Kubde, Rajesh; Makade, Chetana; Pandey, Swapnil

2015-01-01

Introduction: The objective of this study was to evaluate dentinal defects formed by new rotary system — Protaper next™ (PTN). Materials and Methods: Sixty single-rooted premolars were selected. All specimens were decoronated and divided into four groups, each group having 15 specimens. Group I specimens were prepared by Hand K-files (Mani), Group II with ProTaper Universal (PT; Dentsply Maillefer), Group III with Hero Shaper (HS; Micro-Mega, Besancon, France), and Group IV with PTN (Dentsply Maillefer). Roots of each specimen were sectioned at 3, 6, and 9mm from the apex and were then viewed under a stereomicroscope to evaluate presence or absence of dentinal defects. Results: In roots prepared with hand files (HFs) showed lowest percentage of dentinal defects (6.7%); whereas in roots prepared with PT, HS, and PTN it was 40, 66.7, and 26.7%, respectively. There was significant difference between the HS group and the PTN group (P < 0.05). Conclusion: All rotary files induced defects in root dentin, whereas the hand instruments induced minimal defects. PMID:26069406

Interplant Aboveground Signaling Prompts Upregulation of Auxin Promoter and Malate Transporter as Part of Defensive Response in the Neighboring Plants.

PubMed

Sweeney, Connor; Lakshmanan, Venkatachalam; Bais, Harsh P

2017-01-01

When disrupted by stimuli such as herbivory, pathogenic infection, or mechanical wounding, plants secrete signals such as root exudates and volatile organic compounds (VOCs). The emission of VOCs induces a response in the neighboring plant communities and can improve plant fitness by alerting nearby plants of an impending threat and prompting them to alter their physiology for defensive purposes. In this study, we investigated the role of plant-derived signals, released as a result of mechanical wounding, that may play a role in intraspecific communication between Arabidopsis thaliana communities. Plant-derived signals released by the wounded plant resulted in more elaborate root development in the neighboring, unwounded plants. Such plant-derived signals also upregulated the Aluminum-activated malate transporter ( ALMT1 ) responsible for the secretion of malic acid (MA) and the DR5 promoter, an auxin responsive promoter concentrated in root apex of the neighboring plants. We speculate that plant-derived signal-induced upregulation of root-specific ALMT1 in the undamaged neighboring plants sharing the environment with stressed plants may associate more with the benign microbes belowground. We also observed increased association of beneficial bacterium Bacillus subtilis UD1022 on roots of the neighboring plants sharing environment with the damaged plants. Wounding-induced plant-derived signals therefore induce defense mechanisms in the undamaged, local plants, eliciting a two-pronged preemptive response of more rapid root growth and up-regulation of ALMT1 , resulting in increased association with beneficial microbiome.

Induction of root Fe(lll) reductase activity and proton extrusion by iron deficiency is mediated by auxin-based systemic signalling in Malus xiaojinensis.

PubMed

Wu, Ting; Zhang, Heng-Tao; Wang, Yi; Jia, Wen-Suo; Xu, Xue-Feng; Zhang, Xin-Zhong; Han, Zhen Hai

2012-01-01

Iron is a critical cofactor for a number of metalloenzymes involved in respiration and photosynthesis, but plants often suffer from iron deficiency due to limited supplies of soluble iron in the soil. Iron deficiency induces a series of adaptive responses in various plant species, but the mechanisms by which they are triggered remain largely unknown. Using pH imaging and hormone localization techniques, it has been demonstrated here that root Fe(III) reductase activity and proton extrusion upon iron deficiency are up-regulated by systemic auxin signalling in a Fe-efficient woody plant, Malus xiaojinensis. Split-root experiments demonstrated that Fe-deprivation in a portion of the root system induced a dramatic increase in Fe(III) reductase activity and proton extrusion in the Fe-supplied portion, suggesting that the iron deficiency responses were mediated by a systemic signalling. Reciprocal grafting experiments of M. xiaojinensis with Malus baccata, a plant with no capability to produce the corresponding responses, indicate that the initiation of the systemic signalling is likely to be determined by roots rather than shoots. Iron deficiency induced a substantial increase in the IAA content in the shoot apex and supplying exogenous IAA analogues (NAA) to the shoot apex could mimic the iron deficiency to trigger the corresponding responses. Conversely, preventing IAA transport from shoot to roots blocked the iron deficiency responses. These results strongly indicate that the iron deficiency-induced physiological responses are mediated by systemic auxin signalling.

Sequential depolarization of root cortical and stelar cells induced by an acute salt shock - implications for Na(+) and K(+) transport into xylem vessels.

PubMed

Wegner, Lars H; Stefano, Giovanni; Shabala, Lana; Rossi, Marika; Mancuso, Stefano; Shabala, Sergey

2011-05-01

Early events in NaCl-induced root ion and water transport were investigated in maize (Zea mays L) roots using a range of microelectrode and imaging techniques. Addition of 100 mm NaCl to the bath resulted in an exponential drop in root xylem pressure, rapid depolarization of trans-root potential and a transient drop in xylem K(+) activity (A(K+) ) within ∼1 min after stress onset. At this time, no detectable amounts of Na(+) were released into the xylem vessels. The observed drop in A(K+) was unexpected, given the fact that application of the physiologically relevant concentrations of Na(+) to isolated stele has caused rapid plasma membrane depolarization and a subsequent K(+) efflux from the stelar tissues. This controversy was explained by the difference in kinetics of NaCl-induced depolarization between cortical and stelar cells. As root cortical cells are first to be depolarized and lose K(+) to the environment, this is associated with some K(+) shift from the stelar symplast to the cortex, resulting in K(+) being transiently removed from the xylem. Once Na(+) is loaded into the xylem (between 1 and 5 min of root exposure to NaCl), stelar cells become more depolarized, and a gradual recovery in A(K+) occurs. © 2011 Blackwell Publishing Ltd.

Effect of gingival fibroblasts and ultrasound on dogs' root resorption during orthodontic treatment.

PubMed

Crossman, Jacqueline; Hassan, Ali H; Saleem, Ali; Felemban, Nayef; Aldaghreer, Saleh; Fawzi, Elham; Farid, Mamdouh; Abdel-Ghaffar, Khaled; Gargoum, Ausama; El-Bialy, Tarek

2017-01-01

To investigate the effect of using osteogenic induced gingival fibroblasts (OIGFs) and low intensity pulsed ultrasound (LIPUS) on root resorption lacunae volume and cementum thickness in beagle dogs that received orthodontic tooth movement. Seven beagle dogs were used, from which gingival cells (GCs) were obtained and were induced osteogenically to produce OIGFs. Each third and fourth premolar was randomly assigned to one of the five groups, namely, LIPUS, OIGFs, bone morphogenetic protein-2 (BMP-2), OIGFs + LIPUS, and control. All groups received 4 weeks of bodily tooth movement, then LIPUS-treated groups received LIPUS for 20 min/day for 4 weeks, and OIGFs groups received an injection of OIGFs near the root apex. Microcomputed tomography analysis was used to calculate root resorption lacunae volume and histomorphometric analysis was performed to measure the cementum thickness of each root at 3 root levels on compression and tension sides. There was no significant difference in resorption volume between the treatment groups. OIGFs + LIPUS increased cementum thickness ( P > 0.05) in third premolars near the apex, and LIPUS increased cementum thickness ( P > 0.05) in fourth premolars near the apex. Furthermore, BMP2 increased cementum thickness at the coronal third at the compression side. OIGFs, LIPUS, and BMP-2 can be potential treatments for orthodontically induced root resorption, however, improvements in experimental design and treatment parameters are required to further investigate these repair modalities.

Indole-3-butyric acid induces lateral root formation via peroxisome-derived indole-3-acetic acid and nitric oxide.

PubMed

Schlicht, Markus; Ludwig-Müller, Jutta; Burbach, Christian; Volkmann, Dieter; Baluska, Frantisek

2013-10-01

Controlled plant growth requires regulation through a variety of signaling molecules, including steroids, peptides, radicals of oxygen and nitrogen, as well as the 'classical' phytohormone groups. Auxin is critical for the control of plant growth and also orchestrates many developmental processes, such as the formation of new roots. It modulates root architecture both slowly, through actions at the transcriptional level and, more rapidly, by mechanisms targeting primarily plasma membrane sensory systems and intracellular signaling pathways. The latter reactions use several second messengers, including Ca(2+) , nitric oxide (NO) and reactive oxygen species (ROS). Here, we investigated the different roles of two auxins, the major auxin indole-3-acetic acid (IAA) and another endogenous auxin indole-3-butyric acid (IBA), in the lateral root formation process of Arabidopsis and maize. This was mainly analyzed by different types of fluorescence microscopy and inhibitors of NO production. This study revealed that peroxisomal IBA to IAA conversion is followed by peroxisomal NO, which is important for IBA-induced lateral root formation. We conclude that peroxisomal NO emerges as a new player in auxin-induced root organogenesis. In particular, the spatially and temporally coordinated release of NO and IAA from peroxisomes is behind the strong promotion of lateral root formation via IBA. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

Changes in root gravitropism, ultrastructure, and calcium balance of pea root statocytes induced by A23187

NASA Astrophysics Data System (ADS)

Belyavskaya, N.

The role for calcium in the regulation of a wide variety of cellular events in plants is well known. Calcium signaling has been implicated in plant gravitropism. A carboxylic acid antibiotic A23187 (calcimycin) has been widely used in biological studies since it can translocate calcium across membranes. Seedlings of Pisum sativum L. cv. Uladovsky germinated in a vertically oriented cylinder of moist filter paper soaked in water during 4.5 day had been treated with 10-5 M A23187 for 12 hr. Tips of primary roots of control and A23187-treated pea seedlings were fixed for electron microscopy and electron cytochemistry. Experiments with Pisum sativum 5- day seedlings placed horizontally for 4 h after treatment with 10 μM A23187 during 12 h found that the graviresponsiveness of their primary roots was lost completely (91 % of roots) or inhibited (24 +/- 6° in comparison with 88 +/- 8° in control). At ultrastructural level, there were observed distribution of amyloplasts around the nucleus, remarkable lengthening of statocytes, advanced vacuolization, changes in dictyosome structure, ER fragmentation, cell wall thinning in A23187-treated statocytes. Cytochemical study has indicated that statocytes exposed to calcimycin have contained a number of Ca-pyroantimonate granules detected Ca 2 + ions in organelles and hyaloplasm (unlike the control ones). The deposits were mainly associated with the plasma membrane. Among organelles, mitochondria were notable for their ability to accumulate Ca 2 +. In amyloplasts, a fine precipitate was predominately located in their stroma and envelope lumens. In cell walls, deposits of the reaction product were observed along the periphery and in the median zone. Localization of electron-dense granules of lead phosphate, which indicated Ca 2 +- ATPase activities in pea statocytes exposed to A23187, was generally consistent with that in untreated roots. Apart from plasma membrane, chromatin, and nucleolus components, the cytochemical reaction product was found in mitochondrial cristae in contrast to control ones. The presence of the precipitate in other Ca 2 +-sequestered organelles was not determined. The data presented suggest that at the ultrastructural level, the effects of the Ca 2 + ionophore manifested in the loss of polarity in statocytes may be functionally related to systems that regulate the intracellular Ca 2 + homeostasis. It is evident that significant increase in Ca 2 + level in A23187-treated statocytes may cause a disbalance in the gravisensor system and/or calcium signaling and therefore to abolish gravitropism of pea roots.

Hydrogen Peroxide-Induced Root Ca2+ and K+ Fluxes Correlate with Salt Tolerance in Cereals: Towards the Cell-Based Phenotyping

PubMed Central

Zhou, Meixue; Shabala, Sergey

2018-01-01

Salinity stress-induced production of reactive oxygen species (ROS) and associated oxidative damage is one of the major factors limiting crop production in saline soils. However, the causal link between ROS production and stress tolerance is not as straightforward as one may expect, as ROS may also play an important signaling role in plant adaptive responses. In this study, the causal relationship between salinity and oxidative stress tolerance in two cereal crops—barley (Hordeum vulgare) and wheat (Triticum aestivum)—was investigated by measuring the magnitude of ROS-induced net K+ and Ca2+ fluxes from various root tissues and correlating them with overall whole-plant responses to salinity. We have found that the association between flux responses to oxidative stress and salinity stress tolerance was highly tissue specific, and was also dependent on the type of ROS applied. No correlation was found between root responses to hydroxyl radicals and the salinity tolerance. However, when oxidative stress was administered via H2O2 treatment, a significant positive correlation was found for the magnitude of ROS-induced K+ efflux and Ca2+ uptake in barley and the overall salinity stress tolerance, but only for mature zone and not the root apex. The same trends were found for wheat. These results indicate high tissue specificity of root ion fluxes response to ROS and suggest that measuring the magnitude of H2O2-induced net K+ and Ca2+ fluxes from mature root zone may be used as a tool for cell-based phenotyping in breeding programs aimed to improve salinity stress tolerance in cereals. PMID:29494514

[Morphogenesis in formative process in vitro from Rehmannia glutinosa].

PubMed

Xue, Jian-ping; Zhang, Ai-min; Liu, Jun; Xu, Xue-feng

2004-01-01

To study the morphogenesis in formative process of tuberous root in vitro from Rehmannia glutinosa and compare the anatomical shape of tuberous root with nature term R. glutinosa. Tuberous roots of different vegetal phase were cut and dyed, then made into paraffin cuts and observed microscope. In anatomical shape, nature R. glutinosa and tuberous root were the same, which showed that no structural variation occurred in tuberous root induced process.

An experimental comparative study of the efficiency of twisted and flat flapping wings during hovering flight.

PubMed

Phan, Hoang Vu; Truong, Quang Tri; Park, Hoon Cheol

2017-04-19

This work presents a parametric study to find a proper wing configuration for achieving economical flight using unsteady blade element theory, which is based on the 3D kinematics of a flapping wing. Power loading was first considered as a performance parameter for the study. The power loadings at each wing section along the wingspan were obtained for various geometric angles of attack (AoAs) by calculating the ratios of the vertical forces generated and the power consumed by that particular wing section. The results revealed that the power loading of a negatively twisted wing could be higher than the power loading that a flat wing can have; the power loading of the negatively twisted wing was approximately 5.9% higher. Given the relatively low average geometric AoA (α A,root   ≈  44° and α A,tip   ≈  25°), the vertical force produced by the twisted wing for the highest power loading was approximately 24.4% less than that produced by the twisted wing for the strongest vertical force. Therefore, for a given wing geometry and flapping amplitude, a flapping-wing micro air vehicle required a 13.5% increase in flapping frequency to generate the same strongest cycle-average vertical force while saving about 24.3% power. However, when force 3 /power 2 and force 2 /power ratios were considered as performance indices, the twisted wings for the highest force 3 /power 2 (α A,root   ≈  43° and α A,tip   ≈  30°) and force 2 /power (α A,root   ≈  43° and α A,tip   ≈  36°) required only 6.5% and 4% increases in flapping frequency and consumed 26.2% and 25.3% less power, respectively. Thus, it is preferable to use a flapping wing operating at a high frequency using the geometric AoAs for the highest power loading, force 3 /power 2 ratio, and force 2 /power ratio over a flapping wing operating at a low frequency using a high geometric AoA with the strongest vertical force. Additionally, by considering both aerodynamic and inertial forces, this study obtained average geometric AoAs in the range of 30° to 40°, which are similar to those of a typical hovering insect's wings. Therefore, the operation of an aerodynamically uneconomical, high AoA in a hovering insect's wings during flight is explainable.

TAA1-regulated local auxin biosynthesis in the root-apex transition zone mediates the aluminum-induced inhibition of root growth in Arabidopsis.

PubMed

Yang, Zhong-Bao; Geng, Xiaoyu; He, Chunmei; Zhang, Feng; Wang, Rong; Horst, Walter J; Ding, Zhaojun

2014-07-01

The transition zone (TZ) of the root apex is the perception site of Al toxicity. Here, we show that exposure of Arabidopsis thaliana roots to Al induces a localized enhancement of auxin signaling in the root-apex TZ that is dependent on TAA1, which encodes a Trp aminotransferase and regulates auxin biosynthesis. TAA1 is specifically upregulated in the root-apex TZ in response to Al treatment, thus mediating local auxin biosynthesis and inhibition of root growth. The TAA1-regulated local auxin biosynthesis in the root-apex TZ in response to Al stress is dependent on ethylene, as revealed by manipulating ethylene homeostasis via the precursor of ethylene biosynthesis 1-aminocyclopropane-1-carboxylic acid, the inhibitor of ethylene biosynthesis aminoethoxyvinylglycine, or mutant analysis. In response to Al stress, ethylene signaling locally upregulates TAA1 expression and thus auxin responses in the TZ and results in auxin-regulated root growth inhibition through a number of auxin response factors (ARFs). In particular, ARF10 and ARF16 are important in the regulation of cell wall modification-related genes. Our study suggests a mechanism underlying how environmental cues affect root growth plasticity through influencing local auxin biosynthesis and signaling. © 2014 American Society of Plant Biologists. All rights reserved.

Rice Genotype Differences in Tolerance of Zinc-Deficient Soils: Evidence for the Importance of Root-Induced Changes in the Rhizosphere

PubMed Central

Mori, Asako; Kirk, Guy J. D.; Lee, Jae-Sung; Morete, Mark J.; Nanda, Amrit K.; Johnson-Beebout, Sarah E.; Wissuwa, Matthias

2016-01-01

Zinc (Zn) deficiency is a major constraint to rice production and Zn is also often deficient in humans with rice-based diets. Efforts to breed more Zn-efficient rice are constrained by poor understanding of the mechanisms of tolerance to deficiency. Here we assess the contributions of root growth and root Zn uptake efficiency, and we seek to explain the results in terms of specific mechanisms. We made a field experiment in a highly Zn-deficient rice soil in the Philippines with deficiency-tolerant and -sensitive genotypes, and measured growth, Zn uptake and root development. We also measured the effect of planting density. Tolerant genotypes produced more crown roots per plant and had greater uptake rates per unit root surface area; the latter was at least as important as root number to overall tolerance. Tolerant and sensitive genotypes took up more Zn per plant at greater planting densities. The greater uptake per unit root surface area, and the planting density effect can only be explained by root-induced changes in the rhizosphere, either solubilizing Zn, or neutralizing a toxin that impedes Zn uptake (possibly HCO3− or Fe2+), or both. Traits for these and crown root number are potential breeding targets. PMID:26793198

Rice Genotype Differences in Tolerance of Zinc-Deficient Soils: Evidence for the Importance of Root-Induced Changes in the Rhizosphere.

PubMed

Mori, Asako; Kirk, Guy J D; Lee, Jae-Sung; Morete, Mark J; Nanda, Amrit K; Johnson-Beebout, Sarah E; Wissuwa, Matthias

2015-01-01

Zinc (Zn) deficiency is a major constraint to rice production and Zn is also often deficient in humans with rice-based diets. Efforts to breed more Zn-efficient rice are constrained by poor understanding of the mechanisms of tolerance to deficiency. Here we assess the contributions of root growth and root Zn uptake efficiency, and we seek to explain the results in terms of specific mechanisms. We made a field experiment in a highly Zn-deficient rice soil in the Philippines with deficiency-tolerant and -sensitive genotypes, and measured growth, Zn uptake and root development. We also measured the effect of planting density. Tolerant genotypes produced more crown roots per plant and had greater uptake rates per unit root surface area; the latter was at least as important as root number to overall tolerance. Tolerant and sensitive genotypes took up more Zn per plant at greater planting densities. The greater uptake per unit root surface area, and the planting density effect can only be explained by root-induced changes in the rhizosphere, either solubilizing Zn, or neutralizing a toxin that impedes Zn uptake (possibly [Formula: see text] or Fe(2+)), or both. Traits for these and crown root number are potential breeding targets.

Actin Turnover-Mediated Gravity Response in Maize Root Apices

PubMed Central

Mancuso, Stefano; Barlow, Peter W; Volkmann, Dieter

2006-01-01

The dynamic actin cytoskeleton has been proposed to be linked to gravity sensing in plants but the mechanistic understanding of these processes remains unknown. We have performed detailed pharmacological analyses of the role of the dynamic actin cytoskeleton in gravibending of maize (Zea mays) root apices. Depolymerization of actin filaments with two drugs having different mode of their actions, cytochalasin D and latrunculin B, stimulated root gravibending. By contrast, drug-induced stimulation of actin polymerization and inhibition of actin turnover, using two different agents phalloidin and jasplakinolide, compromised the root gravibending. Importantly, all these actin drugs inhibited root growth to similar extents suggesting that high actin turnover is essential for the gravity-related growth responses rather than for the general growth process. Both latrunculin B and cytochalasin D treatments inhibited root growth but restored gravibending of the decapped root apices, indicating that there is a strong potential for effective actin-mediated gravity sensing outside the cap. This elusive gravity sensing outside the root cap is dependent not only on the high rate of actin turnover but also on weakening of myosin activities, as general inhibition of myosin ATPases induced stimulation of gravibending of the decapped root apices. Collectively, these data provide evidence for the actin turnover-mediated gravity sensing outside the root cap. PMID:19521476

Processing vertical size disparities in distinct depth planes.

PubMed

Duke, Philip A; Howard, Ian P

2012-08-17

A textured surface appears slanted about a vertical axis when the image in one eye is horizontally enlarged relative to the image in the other eye. The surface appears slanted in the opposite direction when the same image is vertically enlarged. Two superimposed textured surfaces with different horizontal size disparities appear as two surfaces that differ in slant. Superimposed textured surfaces with equal and opposite vertical size disparities appear as a single frontal surface. The vertical disparities are averaged. We investigated whether vertical size disparities are averaged across two superimposed textured surfaces in different depth planes or whether they induce distinct slants in the two depth planes. In Experiment 1, two superimposed textured surfaces with different vertical size disparities were presented in two depth planes defined by horizontal disparity. The surfaces induced distinct slants when the horizontal disparity was more than ±5 arcmin. Thus, vertical size disparities are not averaged over surfaces with different horizontal disparities. In Experiment 2 we confirmed that vertical size disparities are processed in surfaces away from the horopter, so the results of Experiment 1 cannot be explained by the processing of vertical size disparities in a fixated surface only. Together, these results show that vertical size disparities are processed separately in distinct depth planes. The results also suggest that vertical size disparities are not used to register slant globally by their effect on the registration of binocular direction of gaze.

Identification of genes induced in proteoid roots of white lupin under nitrogen and phosphorus deprivation, with functional characterization of a formamidase

USDA-ARS?s Scientific Manuscript database

White lupin (Lupinus albus L.) is considered a model system for understanding plant acclimation to nutrient deficiency. It acclimates to phosphorus (P) and iron (Fe) deficiency by the development of short, densely clustered lateral roots called proteoid (or cluster) roots; proteoid-root development ...

Plant roots use a patterning mechanism to position lateral root branches toward available water.

PubMed

Bao, Yun; Aggarwal, Pooja; Robbins, Neil E; Sturrock, Craig J; Thompson, Mark C; Tan, Han Qi; Tham, Cliff; Duan, Lina; Rodriguez, Pedro L; Vernoux, Teva; Mooney, Sacha J; Bennett, Malcolm J; Dinneny, José R

2014-06-24

The architecture of the branched root system of plants is a major determinant of vigor. Water availability is known to impact root physiology and growth; however, the spatial scale at which this stimulus influences root architecture is poorly understood. Here we reveal that differences in the availability of water across the circumferential axis of the root create spatial cues that determine the position of lateral root branches. We show that roots of several plant species can distinguish between a wet surface and air environments and that this also impacts the patterning of root hairs, anthocyanins, and aerenchyma in a phenomenon we describe as hydropatterning. This environmental response is distinct from a touch response and requires available water to induce lateral roots along a contacted surface. X-ray microscale computed tomography and 3D reconstruction of soil-grown root systems demonstrate that such responses also occur under physiologically relevant conditions. Using early-stage lateral root markers, we show that hydropatterning acts before the initiation stage and likely determines the circumferential position at which lateral root founder cells are specified. Hydropatterning is independent of endogenous abscisic acid signaling, distinguishing it from a classic water-stress response. Higher water availability induces the biosynthesis and transport of the lateral root-inductive signal auxin through local regulation of tryptophan aminotransferase of Arabidopsis 1 and PIN-formed 3, both of which are necessary for normal hydropatterning. Our work suggests that water availability is sensed and interpreted at the suborgan level and locally patterns a wide variety of developmental processes in the root.

Difference in quick phases induced by horizontal and vertical vestibular stimulations: role of the otolithic input.

PubMed

Pettorossi, V E; Errico, P; Ferraresi, A

1997-01-01

Quick phases (QPs) induced by horizontal and vertical sinusoidal vestibular stimulations were studied in rabbits, cats, and humans. In all the animals, large and frequent horizontal QPs were observed following yaw stimulation in prone position. By contrast, QPs were almost absent during roll stimulation in rabbits, and they were small and oblique during pitch stimulation in cats and humans. As a result of these differences, the range of gaze displacement induced by vestibular stimulations was greater in the horizontal plane than in the vertical one. We also found that the trajectory of the QPs in rabbits was kept horizontal even when the yaw rotation was off vertical axis of +/- 45 degrees in the sagittal plane. Moreover, in the rabbit, the rare horizontal QPs induced by roll stimulation did not change their orientation at various pitch angles of roll stimulation axis. The QPs were also analyzed following roll stimulation of the rabbit in supine position. In this condition, in which the otolithic receptors were activated in the opposite way compared to prone position, large vertical QPs were elicited. We concluded that these results provide evidence that the otolithic signal plays a role in controlling occurrence and trajectory orientation of the QPs.

ABNORMAL INFLORESCENCE MERISTEM1 Functions in Salicylic Acid Biosynthesis to Maintain Proper Reactive Oxygen Species Levels for Root Meristem Activity in Rice.

PubMed

Xu, Lei; Zhao, Hongyu; Ruan, Wenyuan; Deng, Minjuan; Wang, Fang; Peng, Jinrong; Luo, Jie; Chen, Zhixiang; Yi, Keke

2017-03-01

Root meristem activity determines root growth and root architecture and consequently affects water and nutrient uptake in plants. However, our knowledge about the regulation of root meristem activity in crop plants is very limited. Here, we report the isolation and characterization of a short root mutant in rice ( Oryza sativa ) with reduced root meristem activity. This root growth defect is caused by a mutation in ABNORMAL INFLORESCENCE MERISTEM1 ( AIM1 ), which encodes a 3-hydroxyacyl-CoA dehydrogenase, an enzyme involved in β-oxidation. The reduced root meristem activity of aim1 results from reduced salicylic acid (SA) levels and can be rescued by SA application. Furthermore, reduced SA levels are associated with reduced levels of reactive oxygen species (ROS) in aim1 , likely due to increased expression of redox and ROS-scavenging-related genes, whose increased expression is (at least in part) caused by reduced expression of the SA-inducible transcriptional repressors WRKY62 and WRKY76. Like SA, ROS application substantially increased root length and root meristem activity in aim1 These results suggest that AIM1 is required for root growth in rice due to its critical role in SA biosynthesis: SA maintains root meristem activity through promoting ROS accumulation by inducing the activity of WRKY transcriptional repressors, which repress the expression of redox and ROS-scavenging genes. © 2017 American Society of Plant Biologists. All rights reserved.

Comparison of the intrusion effects on the maxillary incisors between implant anchorage and J-hook headgear.

PubMed

Deguchi, Toru; Murakami, Takashi; Kuroda, Shingo; Yabuuchi, Toshinori; Kamioka, Hiroshi; Takano-Yamamoto, Teruko

2008-05-01

Recently, miniscrews have been used to provide anchorage during orthodontic treatment, especially for incisor intrusion. Miniscrews during incisor intrusion are commonly used in implant orthodontics. Traditionally, effective incisor intrusion has been accomplished with J-hook headgear. In this study, we compared the effect of incisor intrusion, force vector, and amount of root resorption between implant orthodontics and J-hook headgear. Lateral cephalometric radiographs from 8 patients in the implant group and 10 patients in the J-hook headgear group were analyzed for incisor retraction. The estimated force vector was analyzed in the horizontal and vertical directions in both groups. Root resorption was also measured on periapical radiographs. In the implant group, significant reductions in overjet, overbite, maxillary incisor to palatal plane, and maxillary incisor to upper lip were observed after intrusion of the incisors. In the J-hook headgear group, significant reductions in overjet, overbite, maxillary incisor to upper lip, and maxillary incisor to SN plane were observed after intrusion of the incisors. There were significantly greater reductions in overbite, maxillary incisor to palatal plane, and maxillary incisor to upper lip in the implant group than in the J-hook headgear group. Estimated force analysis resulted in significantly more force in the vertical direction and less in the horizontal direction in the implant group. Furthermore, significantly less root resorption was observed in the implant group compared with the J-hook headgear group. The maxillary incisors were effectively intruded by using miniscrews as orthodontic anchorage without patient cooperation. The amount of root resorption was not affected by activating the ligature wire from the miniscrew during incisor intrusion.

Autotransplantation of a maxillary third molar to replace a maxillary premolar with vertical root fracture.

PubMed

Tsurumachi, T; Kakehashi, Y

2007-12-01

To report the successful autotransplantation of a fully developed third molar that required nonsurgical and surgical interventions for tooth adaptation. This case report describes the autotransplantation of a third molar with complete root development after the loss of a fractured premolar in a 47-year-old male. To allow better adaptation of the donor tooth, the buccal roots of the third molar were removed using a diamond bur and the canal entrances were filled. Recall examination 6 years after completion of root-canal treatment showed normal periodontal healing with absence of infection, ankylosis or progressive resorption. The transplantation of a third molar is seen as a promising method to replace a lost permanent tooth, and to restore aesthetics and function. *Autotransplantation is a viable option for the treatment of a missing tooth or for replacement of traumatized tooth when there is a donor tooth available. *Fully developed third molars are potentially reliable candidates in the absence of other suitable donor teeth.

Autogenous transplantation of mandibular third molar to replace tooth with vertical root fracture

PubMed Central

Asgary, Saeed

2009-01-01

Autogenous tooth transplantation (ATT) can be considered when there is a hopeless molar tooth and suitable donor present. This report presents an unconventional case of successful ATT of a third molar replacing the adjacent fractured second molar in a 33 year old woman. This wisdom tooth had completely developed roots. Root-end filling with Calcium Enriched Mixture (CEM) cement was performed in the third molar. The second molar was extracted non-traumatically without any bone removal; the wisdom tooth was immediately transplanted into the recipient socket. No endodontic treatment was carried out either during or after the ATT. At six-month and 2-year clinical examination the patient was asymptomatic; the transplanted tooth was still functional, with no evidence of marginal periodontal pathosis. At the same follow ups, radiographic evaluation illustrated bone regeneration, normal PDL, and absence of external root resorption. Transplantation of mature third molar seems to be a promising method for replacing a lost permanent molar tooth and restoring aesthetics and function. PMID:24003333

Evaluation of canal filling after using two warm vertical gutta-percha compaction techniques in vivo: a preliminary study.

PubMed

Venturi, M

2006-07-01

To evaluate the quality of root canal filling when comparing two warm gutta-percha filling techniques in vivo. Human teeth were randomly divided into two equal groups, with 30 canals each. The root canals were shaped by hand and ProFile 0.04 rotary instruments to size 20-40 at the end-point and then filled with gutta-percha cones and AH-Plus. In group A, a traditional warm vertical compaction technique was performed using the Touch'n Heat, and back-filling with the Obtura II. In group B, a modified warm vertical compaction technique was used: small amounts of gutta-percha were removed, and the remaining most apical 3 mm were compacted with a 1 mm movement; then thermomechanical back-filling was performed. The teeth were extracted, stored in dye, cleared, and the distance between the apex and apical limit of the filling, linear dye penetration, and voids were measured from the buccal, lingual, mesial and distal perspective. The homogeneity of variance and means was verified using Levene's test and t-test. ANOVA and Dunnett post hoc test were used to establish the significance and to analyse the effects through multiple comparisons. Compared with the specimens of group A, the specimens of group B exhibited less mean linear dye penetration (P < 0.05), smaller void length (P < or = 0.05) and maximal width (P < or = 0.05) when examined in all four views, and a more precise filling when viewed from the buccal aspect (P < 0.05). The modified warm vertical compaction technique with apical back-filling produced a more effective and precise three-dimensional filling.

Analysis of age-dependence of the anterior and posterior cornea with scheimpflug imaging.

PubMed

Nemeth, Gabor; Hassan, Ziad; Szalai, Eszter; Berta, Andras; Modis, Laszlo

2013-05-01

To assess keratometric and higher-order aberrations of the anterior and posterior cornea and their age-related changes. This study investigated one healthy eye of 227 patients (mean age: 55.15 ± 21.2 years; range: 16 to 90 years; 135 right eyes, 92 left eyes). Images were captured from each eye with Pentacam HR (Oculus Optikgeräte GmbH, Wetzlar, Germany) using automatic mode. Keratometric, astigmatism data, and corneal higher-order aberrations were analyzed. With respect to laterality, no deviance was found in any of the parameters (P > .05). Mean refractive error was 0.52 ± 0.23 diopters. The level of astigmatism decreased significantly with advancing age for both the anterior and posterior corneal surfaces (P < .05). The overall root mean square of the higher-order aberration increased continuously with age (r = 0.517; P < .01), which can be explained by the combined effect of the increased in both the anterior and posterior corneal root mean square higher-order aberrations. Of the higher-order aberrations, the constant increase of the primary and secondary spherical aberration with aging (P < .01) is caused by the spherical aberration growth of the anterior surface. Apart from these, only the vertical coma aberration of the posterior surface and the vertical trefoil aberrations of both the anterior and posterior surfaces showed a significantly positive correlation with aging (P < .05). Corneal astigmatism showed a significant decrease with aging. Of the higher-order aberrations, primary and secondary spherical aberrations, vertical coma, and vertical trefoil significantly increase with age, whereas other higher-order aberrations show no correlation with aging. Copyright 2013, SLACK Incorporated.

An auxin-induced β-type endo-1,4-β-glucanase in poplar is involved in cell expansion and lateral root formation.

PubMed

Yu, Liangliang; Li, Qiong; Zhu, Yingying; Afzal, Muhammad Saddique; Li, Laigeng

2018-05-01

PtrGH9A7, a poplar β-type endo-1,4-β-glucanase gene induced by auxin, promotes both plant growth and lateral root development by enhancing cell expansion. Endo-1,4-β-glucanase (EGase) family genes function in multiple aspects of plant growth and development. Our previous study found that PtrCel9A6, a poplar EGase gene of the β subfamily, is specifically expressed in xylem tissue and is involved in the cellulose biosynthesis required for secondary cell wall formation (Yu et al. in Mol Plant 6:1904-1917, 2013). To further explore the functions and regulatory mechanism of β-subfamily EGases, we cloned and characterized another poplar β-type EGase gene PtrGH9A7, a close homolog of PtrCel9A6. In contrast to PtrCel9A6, PtrGH9A7 is predominantly expressed in parenchyma tissues of the above-ground part; in roots, PtrGH9A7 expression is specifically restricted to lateral root primordia at all stages from initiation to emergence and is strongly induced by auxin application. Heterologous overexpression of PtrGH9A7 promotes plant growth by enhancing cell expansion, suggesting a conserved role for β-type EGases in 1,4-β-glucan chains remodeling, which is required for cell wall loosening. Moreover, the overexpression of PtrGH9A7 significantly increases lateral root number, which might result from improved lateral root primordium development due to enhanced cell expansion. Taken together, these results demonstrate that this β-type EGase induced by auxin signaling has a novel role in promoting lateral root formation as well as in enhancing plant growth.

Transcriptional regulation of host NH₄⁺ transporters and GS/GOGAT pathway in arbuscular mycorrhizal rice roots.

PubMed

Pérez-Tienda, Jacob; Corrêa, Ana; Azcón-Aguilar, Concepción; Ferrol, Nuria

2014-02-01

Arbuscular mycorrhizal (AM) fungi play a key role in the nutrition of many land plants. AM roots have two pathways for nutrient uptake, directly through the root epidermis and root hairs and via AM fungal hyphae into root cortical cells, where arbuscules or hyphal coils provide symbiotic interfaces. Recent studies demonstrated that the AM symbiosis modifies the expression of plant transporter genes and that NH₄⁺ is the main form of N transported in the symbiosis. The aim of the present work was to get insights into the mycorrhizal N uptake pathway in Oryza sativa by analysing the expression of genes encoding ammonium transporters (AMTs), glutamine synthase (GS) and glutamate synthase (GOGAT) in roots colonized by the AM fungus Rhizophagus irregularis and grown under two N regimes. We found that the AM symbiosis down-regulated OsAMT1;1 and OsAMT1;3 expression at low-N, but not at high-N conditions, and induced, independently of the N status of the plant, a strong up-regulation of OsAMT3;1 expression. The AM-inducible NH₄⁺ transporter OsAMT3;1 belongs to the family 2 of plant AMTs and is phylogenetically related to the AM-inducible AMTs of other plant species. Moreover, for the first time we provide evidence of the specific induction of a GOGAT gene upon colonization with an AM fungus. These data suggest that OsAMT3;1 is likely involved in the mycorrhizal N uptake pathway in rice roots and that OsGOGAT2 plays a role in the assimilation of the NH₄⁺ supplied via the OsAMT3;1 AM-inducible transporter. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Molecular genetics of root gravitropism and waving in Arabidopsis thaliana

NASA Technical Reports Server (NTRS)

Sedbrook, J.; Boonsirichai, K.; Chen, R.; Hilson, P.; Pearlman, R.; Rosen, E.; Rutherford, R.; Batiza, A.; Carroll, K.; Schulz, T.;

4. LOWER NOTTINGHAM MINE. DETAIL OF OBJECTS ASSOCIATED WITH CABIN ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

4. LOWER NOTTINGHAM MINE. DETAIL OF OBJECTS ASSOCIATED WITH CABIN 'B'; PIPE, WOOD, STOVE MATERIALS, AND COLLAPSED ROOT CELLAR IN CENTRAL AREA. VERTICAL, DARK PIPE IS VISIBLE IN CENTER/UPPER THIRD. CAMERA POINTED EAST. - Florida Mountain Mining Sites, Lower Nottingham Mine, Western slope of Florida Mountain, Silver City, Owyhee County, ID

Minimally invasive flap surgery and enamel matrix derivative in the treatment of localized aggressive periodontitis: case report.

PubMed

Kaner, Doğan; Bernimoulin, Jean-Pierre; Kleber, Bernd-Michael; Friedmann, Anton

2009-02-01

Localized aggressive periodontitis is a distinct entity of periodontal disease and is characterized by deep vertical bony defects that typically affect the first molars and incisors of young patients. Therapy is usually aimed at reducing the pathogenic microflora through scaling and root planing and the administration of systemic antibiotics. However, conservative periodontal therapy may result in reparative wound healing with limited regeneration of the lost tissues. Periodontal surgery combined with enamel matrix derivative has been introduced as a method to promote regeneration of the lost periodontium and has been studied extensively in the treatment of chronic periodontitis. This case report describes the treatment of a 27-year-old patient displaying severe localized aggressive periodontitis with documented disease progression. After initial therapy consisting of scaling and root planing and systemic administration of amoxicillin and metronidazole, the vertical defects were treated by minimally invasive access flaps combined with application of enamel matrix derivative. Clinical, microbiologic, and radiographic findings are reported for up to 1.5 years after initial therapy, indicating good efficacy of the therapeutic strategy and stability of the treatment outcome.

Severely Reduced Gravitropism in Dark-Grown Hypocotyls of a Starch-Deficient Mutant of Nicotiana sylvestris1

PubMed Central

Kiss, John Z.; Sack, Fred D.

1990-01-01

Gravitropism in dark-grown hypocotyls of the wild type was compared with a starch-deficient Nicotiana sylvestris mutant (NS 458) to test the effects of starch deficiency on gravity sensing. In a time course of curvature measured using infrared video, the response of the mutant was greatly reduced compared to the wild type; 72 hours after reorientation, curvature was about 10° for NS 458 and about 70° for wild type. In dishes maintained in a vertical orientation, wild-type hypocotyls were predominantly vertical, whereas NS 458 hypocotyls were severely disoriented with about 5 times more orientational variability than wild type. Since the growth rates were equal for both genotypes and phototropic curvature was only slightly inhibited in NS 458, the mutation probably affects gravity perception rather than differential growth. Our data suggest that starch deficiency reduces gravitropic sensitivity more in dark-grown hypocotyls than in dark- or light-grown roots in this mutant and support the hypothesis that amyloplasts function as statoliths in shoots as well as roots. Images Figure 2 Figure 3 Figure 4 PMID:11537476

Severely reduced gravitropism in dark-grown hypocotyls of a starch-deficient mutant of Nicotiana sylvestris

NASA Technical Reports Server (NTRS)

Kiss, J. Z.; Sack, F. D.

1990-01-01

Gravitropism in dark-grown hypocotyls of the wild type was compared with a starch-deficient Nicotiana sylvestris mutant (NS 458) to test the effects of starch deficiency on gravity sensing. In a time course of curvature measured using infrared video, the response of the mutant was greatly reduced compared to the wild type; 72 hours after reorientation, curvature was about 10 degrees for NS 458 and about 70 degrees for wild type. In dishes maintained in a vertical orientation, wild-type hypocotyls were predominantly vertical, whereas NS 458 hypocotyls were severely disoriented with about 5 times more orientational variability than wild type. Since the growth rates were equal for both genotypes and phototropic curvature was only slightly inhibited in NS 458, the mutation probably affects gravity perception rather than differential growth. Our data suggest that starch deficiency reduces gravitropic sensitivity more in dark-grown hypocotyls than in dark- or light-grown roots in this mutant and support the hypothesis that amyloplasts function as statoliths in shoots as well as roots.

EIR1, a root-specific protein involved in auxin transport, is required for gravitropism in Arabidopsis thaliana

PubMed Central

Luschnig, Christian; Gaxiola, Roberto A.; Grisafi, Paula; Fink, Gerald R.

1998-01-01

The EIR1 gene of Arabidopsis is a member of a family of plant genes with similarities to bacterial membrane transporters. This gene is expressed only in the root, which is consistent with the phenotypes of the eir1 mutants—the roots are agravitropic and have a reduced sensitivity to ethylene. The roots of eir1 mutants are also insensitive to the excess auxin produced by alf1-1 and fail to induce an auxin-inducible gene in the expansion zone. Although they fail to respond to internally generated auxin, they respond normally to externally applied auxin. Expression of the EIR1 gene in Saccharomyces cerevisiae confers resistance to fluorinated indolic compounds. Taken together, these data suggest that the EIR1 protein has a root-specific role in the transport of auxin. PMID:9679062

Comparative kinetics and reciprocal inhibition of nitrate and nitrite uptake in roots of uninduced and induced barley (Hordeum vulgare L.) seedlings

NASA Technical Reports Server (NTRS)

Aslam, M.; Travis, R. L.; Huffaker, R. C.

1992-01-01

Nitrate and NO2- transport by roots of 8-day-old uninduced and induced intact barley (Hordeum vulgare L. var CM 72) seedlings were compared to kinetic patterns, reciprocal inhibition of the transport systems, and the effect of the inhibitor, p-hydroxymercuribenzoate. Net uptake of NO3- and NO2- was measured by following the depletion of the ions from the uptake solutions. The roots of uninduced seedlings possessed a low concentration, saturable, low Km, possibly a constitutive uptake system, and a linear system for both NO3- and NO2-. The low Km system followed Michaelis-Menten kinetics and approached saturation between 40 and 100 micromolar, whereas the linear system was detected between 100 and 500 micromolar. In roots of induced seedlings, rates for both NO3- and NO2- uptake followed Michaelis-Menten kinetics and approached saturation at about 200 micromolar. In induced roots, two kinetically identifiable transport systems were resolved for each anion. At the lower substrate concentrations, less than 10 micromolar, the apparent low Kms of NO3- and NO2- uptake were 7 and 9 micromolar, respectively, and were similar to those of the low Km system in uninduced roots. At substrate concentrations between 10 and 200 micromolar, the apparent high Km values of NO3- uptake ranged from 34 to 36 micromolar and of NO2- uptake ranged from 41 to 49 micromolar. A linear system was also found in induced seedlings at concentrations above 500 micromolar. Double reciprocal plots indicated that NO3- and NO2- inhibited the uptake of each other competitively in both uninduced and induced seedlings; however, Ki values showed that NO3- was a more effective inhibitor than NO2-. Nitrate and NO2- transport by both the low and high Km systems were greatly inhibited by p-hydroxymercuribenzoate, whereas the linear system was only slightly inhibited.

Effect of phorbol derivatives and staurosporine on gravitropic response of primary root of maize

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mulkey, T.J.; Kim, S.Y.; Lee, J.S.

1991-05-01

Time-lapse videography and computer-based, video image digitization were used to examine the effects of phorbol derivatives (phorbol 12-myristate 13-acetate, TPA; phorbol 12-myristate 13-acetate 4-O-methyl ether, mTPA) and staurosporine on the kinetics of gravicurvature of primary roots of maize (Zea mays L., Pioneer 3343 and Golden Cross Bantam). Pretreatment of roots with TPA (3 hr, 1 {mu}M) decreases the time lag prior to induction of positive gravicurvature in horizontally-oriented roots by > 60%. The rate of curvature is not significantly different than the rate observed in control roots. Wrongway curvature which is observed in 30-40% of control roots is not observedmore » in TPA-pretreated roots. Oscillatory movements observed in control roots after completion of gravitropic reorientation is completely dampened in TPA-pretreated roots. Pretreatment of roots with mTPA(3hr,1{mu}M), the inactive analog of TPA, does not significantly alter the kinetics of gravicurvature of primary roots of maize. Staurosporine (10{sup {minus}8}M), a microbial alkaloid which has been reported to have antifungal activity and to inhibit phospholipid/Ca{sup ++} dependent protein kinase, completely inhibits TPA-induced alteration of the kinetics of gravitropism. DAG (1-oleoyl-2-acetyl-rac-glycerol), a synthetic diglyceride activator of protein kinase C, exhibits similar activity to TPA. TPA-induced alterations in tissue response to auxin are presented.« less

[Role of NO signal in ABA-induced phenolic acids accumulation in Salvia miltiorrhiza hairy roots].

PubMed

Shen, Lihong; Ren, Jiahui; Jin, Wenfang; Wang, Ruijie; Ni, Chunhong; Tong, Mengjiao; Liang, Zongsuo; Yang, Dongfeng

2016-02-01

To investigate roles of nitric oxide (NO) signal in accumulations of phenolic acids in abscisic.acid (ABA)-induced Salvia miltiorrhiza hairy roots, S. miltiorrhiza hairy roots were treated with different concentrations of sodium nitroprusside (SNP)-an exogenous NO donor, for 6 days, and contents of phenolic acids in the hairy roots are determined. Then with treatment of ABA and NO scavenger (2-(4-carboxy-2-phenyl)-4,4,5,5-tetramethylimidazoline-1- oxyl-3-oxide, c-PTIO) or NO synthase inhibitor (NG-nitro-L-arginine methyl ester, L-NAME), contents of phenolic acids and expression levels of three key genes involved in phenolic acids biosynthesis were detected. Phenolic acids production in S. miltiorrhiza hairy roots was most significantly improved by 100 µmoL/L SNP. Contents of RA and salvianolic acid B increased by 3 and 4 folds. ABA significantly improved transcript levels of PAL (phenylalanine ammonia lyase), TAT (tyrosine aminotransferase) and RAS (rosmarinic acid synthase), and increased phenolic acids accumulations. However, with treatments of ABA+c-PTIO or ABA+L-NAME, accumulations of phenolic acids and expression levels of the three key genes were significantly inhibited. Both NO and ABA can increase accumulations of phenolic acids in S. miltiorrhiza hairy roots. NO signal probably mediates the ABA-induced phenolic acids production.

Boron reduces aluminum-induced growth inhibition, oxidative damage and alterations in the cell wall components in the roots of trifoliate orange.

PubMed

Riaz, Muhammad; Yan, Lei; Wu, Xiuwen; Hussain, Saddam; Aziz, Omar; Imran, Muhammad; Rana, Muhammad Shoaib; Jiang, Cuncang

2018-05-30

Aluminum (Al) toxicity is a major restriction for crops production on acidic soils. The primary symptom of aluminum toxicity is visible in the roots of plants. Recently, several studies reported the alleviation of Al toxicity by the application of Boron (B), however, the information how B alleviates Al toxicity is not well understood. Thus, we investigated the ameliorative response of B on Al-induced growth inhibition, oxidative damages, and variations in the cell wall components in trifoliate orange roots. The results indicated that plants under Al stress experienced a substantial decrement in root length and overall plant growth. The supply of B improved the root elongation by eliminating oxidative stress, membrane peroxidation, membrane leakage, and cell death produced under Al toxicity. Moreover, accumulation of Al on the cell wall and alteration in the cell wall components might be one of the causes resulting in the quick inhibition of root elongation under B-starvation circumstances by providing susceptible negative charges on pectin matrix for binding of Al. The results provide a useful understanding of the insight into mechanisms of B-induced mitigation of Al toxicity especially in the trifoliate orange that might be helpful in the production of crops on acidic soils. Copyright © 2018 Elsevier Inc. All rights reserved.

High-efficiency Agrobacterium rhizogenes-mediated transformation of heat inducible sHSP18.2-GUS in Nicotiana tabacum.

PubMed

Chen, Shih-Cheng; Liu, Hui-Wen; Lee, Kung-Ta; Yamakawa, Takashi

2007-01-01

The chimerical gene, Arabidopsis thaliana sHSP18.2 promoter fused to E. coli gusA gene, was Agrobacterium rhizogenes-mediated transformed into Nicotiana tabacum as a heat-regulatable model, and the thermo-inducible expression of GUS activity in N. tabacum transgenic hairy roots was profiled. An activation of A. rhizogenes with acetosyringone (AS) before cocultured with tobacco's leaf disc strongly promoted transgenic hairy roots formation. Transgenic hairy roots formation efficiency of A. rhizogenes precultured with 200 microM AS supplementation was 3.1-fold and 7.5-fold, respectively, compared to the formation efficiency obtained with and without AS supplementation in coculture. Transgenic hairy roots transformed with different AS concentration exhibited a similar pattern of thermo-inducibility after 10 min to 3 h heat treatments detected by GUS expression. The peak of expressed GUS specific activity, 399,530 pmol MUG per mg total protein per min, of the transgenic hairy roots was observed at 48 h after 3 h of 42 degrees C heat treatment, and the expressed GUS specific activity was 7-26 times more than that reported in A. thaliana, tobacco BY-2 cells and Nicotiana plumbaginifolia. Interference caused by AS supplementation on the growth of transgenic hairy roots, time-course of GUS expression and its expression level were not observed.

The Molecular Mechanism of Ethylene-Mediated Root Hair Development Induced by Phosphate Starvation

PubMed Central

Song, Li; Yu, Haopeng; Dong, Jinsong; Liu, Dong

2016-01-01

Enhanced root hair production, which increases the root surface area for nutrient uptake, is a typical adaptive response of plants to phosphate (Pi) starvation. Although previous studies have shown that ethylene plays an important role in root hair development induced by Pi starvation, the underlying molecular mechanism is not understood. In this work, we characterized an Arabidopsis mutant, hps5, that displays constitutive ethylene responses and increased sensitivity to Pi starvation due to a mutation in the ethylene receptor ERS1. hps5 accumulates high levels of EIN3 protein, a key transcription factor involved in the ethylene signaling pathway, under both Pi sufficiency and deficiency. Pi starvation also increases the accumulation of EIN3 protein. Combined molecular, genetic, and genomic analyses identified a group of genes that affect root hair development by regulating cell wall modifications. The expression of these genes is induced by Pi starvation and is enhanced in the EIN3-overexpressing line. In contrast, the induction of these genes by Pi starvation is suppressed in ein3 and ein3eil1 mutants. EIN3 protein can directly bind to the promoter of these genes, some of which are also the immediate targets of RSL4, a key transcription factor that regulates root hair development. Based on these results, we propose that under normal growth conditions, the level of ethylene is low in root cells; a group of key transcription factors, including RSL4 and its homologs, trigger the transcription of their target genes to promote root hair development; Pi starvation increases the levels of the protein EIN3, which directly binds to the promoters of the genes targeted by RSL4 and its homologs and further increase their transcription, resulting in the enhanced production of root hairs. This model not only explains how ethylene mediates root hair responses to Pi starvation, but may provide a general mechanism for how ethylene regulates root hair development under both stress and non-stress conditions. PMID:27427911

In vitro biocompatibility, inflammatory response, and osteogenic potential of 4 root canal sealers: Sealapex, Sankin apatite root sealer, MTA Fillapex, and iRoot SP root canal sealer.

PubMed

Chang, Seok-Woo; Lee, So-Youn; Kang, Soo-Kyung; Kum, Kee-Yeon; Kim, Eun-Cheol

2014-10-01

The objective of this study was to compare the cytotoxicity, inflammatory response, osteogenic effect, and the signaling mechanism of these biologic activities of 4 calcium compound-based root canal sealers (ie, Sealapex [Sybron Kerr, WA], apatite root sealer [ARS; Dentsply Sankin, Tokyo, Japan], MTA Fillapex [Angelus Indústria de Produtos Odontológicos S/A, Londrina, PR, Brazil], and iRoot SP [Innovative BioCreamix Inc, Vancouver, Canada]) in human periodontal ligament cells. Cytotoxicity was assessed using the 3-(4,5-dimethylthiazolyl-2-yl)-2,5-diphenyltetrazolium bromide assay. Levels of inflammatory mediators were measured by enzyme-linked immunosorbent assay, reverse-transcription polymerase chain reaction, and Western blot analysis. Osteogenic potential was evaluated by alkaline phosphatase activity, alizarin red staining, and marker genes by reverse-transcription polymerase chain reaction. The signal transduction pathways were examined by Western blotting. None of the sealers were cytotoxic. ARS, MTA Fillapex, and iRoot SP induced a lower expression of proinflammatory mediators than Sealapex. All sealers increased ALP activity and the formation of mineralized nodules and up-regulated the expression of osteoblastic marker messenger RNA. ARS, MTA Fillapex, and iRoot SP showed superior osteogenic potential compared with Sealapex. The expression and/or activation of integrin receptors and downstream signaling molecules, including focal adhesion kinase, paxillin, Akt, mitogen-activated protein kinase, and nuclear factor κB, was induced by ARS, MTA Fillapex, and iRoot SP treatment but not by Sealapex treatment. We show for the first time that ARS, MTA Fillapex, and iRoot SP induce a lower expression of inflammatory mediators and enhance osteoblastic differentiation of PDLCs via the integrin-mediated signaling pathway compared with Sealapex. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Comparative Analysis of Arabidopsis Ecotypes Reveals a Role for Brassinosteroids in Root Hydrotropism1[OPEN

PubMed Central

Wang, Meng; Yuan, Wei; Ren, Yan; Li, Ying; Zhang, Na; Kronzucker, Herbert J.

2018-01-01

Plant roots respond to soil moisture gradients and remodel their growth orientation toward water through hydrotropism, a process vital for acclimation to a changing soil environment. Mechanisms underlying the root hydrotropic response, however, remain poorly understood. Here, we examined hydrotropism in 31 Arabidopsis (Arabidopsis thaliana) ecotypes collected from different parts of the world and grown along moisture gradients in a specially designed soil-simulation system. Comparative transcriptome profiling and physiological analyses were carried out on three selected ecotypes, Wassilewskija (Ws), Columbia (Col-0) (strongly hydrotropic), Col-0 (moderately hydrotropic), and C24 (weakly hydrotropic), and in mutant lines with altered root hydrotropic responses. We show that H+ efflux, Ca2+ influx, redox homeostasis, epigenetic regulation, and phytohormone signaling may contribute to root hydrotropism. Among phytohormones, the role of brassinosteroids (BRs) was examined further. In the presence of an inhibitor of BR biosynthesis, the strong hydrotropic response observed in Ws was reduced. The root H+ efflux and primary root elongation also were inhibited when compared with C24, an ecotype that showed a weak hydrotropic response. The BR-insensitive mutant bri1-5 displayed higher rates of root growth inhibition and root curvature on moisture gradients in vertical or oblique orientation when compared with wild-type Ws. We also demonstrate that BRI1 (a BR receptor) interacts with AHA2 (a plasma membrane H+-ATPase) and that their expression patterns are highly coordinated. This synergistic action may contribute to the strong hydrotropism observed in Ws. Our results suggest that BR-associated H+ efflux is critical in the hydrotropic response of Arabidopsis roots. PMID:29439211

Colonization by the arbuscular mycorrhizal fungus Glomus versiforme induces a defense response against the root-knot nematode Meloidogyne incognita in the grapevine (Vitis amurensis Rupr.), which includes transcriptional activation of the class III chitinase gene VCH3.

PubMed

Li, Hai-Yan; Yang, Guo-Dong; Shu, Huai-Rui; Yang, Yu-Tao; Ye, Bao-Xing; Nishida, Ikuo; Zheng, Cheng-Chao

2006-01-01

Inoculation of the grapevine (Vitis amurensis Rupr.) with the arbuscular mycorrhizal (AM) fungus Glomus versiforme significantly increased resistance against the root-knot nematode (RKN) Meloidogyne incognita. Studies using relative quantitative reverse transcription-PCR (RQRT-PCR) analysis of grapevine root inoculation with the AM fungus revealed an up-regulation of VCH3 transcripts. This increase was greater than that observed following infection with RKN. However, inoculation of the mycorrhizal grapevine roots with RKN was able to enhance VCH3 transcript expression further. Moreover, the increase in VCH3 transcripts appeared to result in a higher level of resistance against subsequent RKN infection. Constitutive expression of VCH3 cDNA in transgenic tobacco under the control of the cauliflower mosaic virus 35S promoter also conferred resistance against RKN, but had no significant effect on the growth of the AM fungus. We analyzed beta-glucuronidase (GUS) activity directed by a 1,216 bp VCH3 promoter in transgenic tobacco following inoculation with both the AM fungus and RKN. GUS activity was negligible in the root tissues before inoculation, and was more effectively induced after inoculation with the AM fungus than with RKN. Moreover, GUS staining in the mycorrhizal transgenic tobacco roots was enhanced by subsequent RKN infection, and was found ubiquitously throughout the whole root tissue. Together, these results suggest that AM fungus induced a defense response against RKN in the mycorrhizal grapevine roots, which appeared to involve transcriptional control of VCH3 expression throughout the whole root tissue.

Characterization of Rubia cordifolia L. root extract and its evaluation of cardioprotective effect in Wistar rat model

PubMed Central

Chandrashekar, BS; Prabhakara, S; Mohan, T; Shabeer, D; Bhandare, Basavaraj; Nalini, M; Sharmila, PS; Meghana, DL; Reddy, Basanth Kumar; Hanumantha Rao, HM; Sahajananda, H; Anbazhagan, K

2018-01-01

OBJECTIVES: Rubia cordifolia L. (RC) is a well-known and highly valuable medicinal plant in the Ayurvedic system. The present study involves evaluating antioxidant and cardioprotective property of RC root extract. MATERIALS AND METHODS: The characterization of RC root extract was carried out using standard phytochemical and biochemical analysis. The functional groups were analyzed by Fourier transform infrared (FTIR) spectroscopy and phytotherapeutic compounds were identified using high-resolution mass spectrometry (HR-MS). Cardioprotective activity of RC root extract was investigated against cyclophosphamide (CP; 100 mg/kg, i.p)-induced cardiotoxicity in male albino Wistar rats. RC (100, 200, and 400 mg/kg, p.o) or silymarin (100 mg/kg, p.o) was administered immediately after CP on the 1st day and the next consecutive 10 days. Biochemical and histopathological analysis was performed to observe the cardioprotective effects of RC root extract. RESULTS: Phytochemical analysis revealed the presence of secondary metabolites that include alkaloids, flavonoids, saponins, and anthraquinones in RC root extract. FTIR analysis revealed the presence of several functional groups. Based on HR-MS analysis, eight major phytotherapeutic compounds were identified in methanol root extract of RC. Biochemical analysis in CP-induced rat model administered with RC extract revealed significantly enhanced levels of antioxidant markers such as superoxide dismutase, catalase, and glutathione S-transferase. Histopathological study showed that the rat model treated with the root extract had reduced the cardiac injury. CONCLUSION: Our results have shown that the RC extract contains various antioxidant compounds with cardioprotective effect. Treatment with RC root extract could significantly protect CP-induced rats from cardiac tissue injury by restoring the antioxidant markers. PMID:29861523

Interactions Between Pinus taeda (loblolly) Fine Roots and Soil Fungi: Impacts of Elevated CO2, N Availability, and Spatial Distribution of Fungi on Fine Root Persistence and Turnover

NASA Astrophysics Data System (ADS)

Strand, A.; Beidler, K.; McGlinn, D.; Pritchard, S. G.

2016-12-01

Fine root turnover represents the most significant mode of flux from plants into soil C pools. Unfortunately fine root senescence and decomposition, processes critical in turnover, are particularly understudied. For example, little is known about either the factors that influence fine-root decomposition or the fate of compounds they contain during root death. Better understanding fine root senescence and decomposition should reduce uncertainty associated with global climate models; including re-uptake of materials in dying leaves into these models has already been shown to increase their accuracy. Over 4400 individual fine-roots and 4734 rhizomorphs were tracked from initiation until disintegration over 12 years using minirhizotrons at the Duke FACE site. Image-based approaches such as minirhizotrons cannot directly assess fine-root physiological status. To assess fine-root function directly, we are now conducting manipulative experiments in P. taeda in which fine-root senescence is induced through two treatments, steam- and direct hand-girdling. Physiological status is then assessed by examining gene-expression, root anatomy and chemical composition of manipulated roots. Changing [CO2] did not change persistence times for roots, but did impact rhizomorph persistence. Both roots and rhizomorphs showed interactions between effects of N and CO2 on persistence. Most interesting is the interaction between fine-roots and rhizomorphs: fine root persistence times are reduced in the presence of rhizomorphs, but this effect depends on the amount of N available. Finally, we found experimentally inducing senescence via steam girdling to be very effective relative to hand-girdling. These results provide evidence of the importance of priming on function of soil fungi and the role of N availability on fine-root turnover. The ability to stimulate fine-root senescence provides a powerful experimental tool to examine the fates of resources contained in fine-root pools as these roots turn over.

Stretching of roots contributes to the pathophysiology of radiculopathies.

PubMed

Berthelot, Jean-Marie; Laredo, Jean-Denis; Darrieutort-Laffite, Christelle; Maugars, Yves

2018-01-01

To perform a synthesis of articles addressing the role of stretching on roots in the pathophysiology of radiculopathy. Review of relevant articles on this topic available in the PubMed database. An intraoperative microscopy study of patients with sciatica showed that in all patients the hernia was adherent to the dura mater of nerve roots. During the SLR (Lasègue's) test, the limitation of nerve root movement occurs by periradicular adhesive tissue, and temporary ischemic changes in the nerve root induced by the root stretching cause transient conduction disturbances. Spinal roots are more frail than peripheral nerves, and other mechanical stresses than root compression can also induce radiculopathy, especially if they also impair intraradicular blood flow, or the function of the arachnoid villi intimately related to radicular veins. For instance arachnoiditis, the lack of peridural fat around the thecal sac, and epidural fibrosis following surgery, can all promote sciatica, especially in patients whose sciatic trunks also stick to piriformis or internus obturator muscles. Indeed, stretching of roots is greatly increased by adherence at two levels. As excessive traction of nerve roots is not shown by imaging, many physicians have unlearned to think in terms of microscopic and physiologic changes, although nerve root compression in the lumbar MRI is lacking in more than 10% of patients with sciatica. It should be reminded that, while compression of a spinal nerve root implies stretching of this root, the reverse is not true: stretching of some roots can occur without any visible compression. Copyright © 2017 Société française de rhumatologie. Published by Elsevier SAS. All rights reserved.

Combining Bioactive Multifunctional Dental Composite with PAMAM for Root Dentin Remineralization

PubMed Central

Xiao, Shimeng; Liang, Kunneng; Weir, Michael D.; Cheng, Lei; Liu, Huaibing; Zhou, Xuedong; Ding, Yi; Xu, Hockin H. K.

2017-01-01

Objectives. The objectives of this study were to: (1) develop a bioactive multifunctional composite (BMC) via nanoparticles of amorphous calcium phosphate (NACP), 2-methacryloyloxyethyl phosphorylcholine (MPC), dimethylaminohexadecyl methacrylate (DMAHDM) and nanoparticles of silver (NAg); and (2) investigate the effects of combined BMC + poly (amido amine) (PAMAM) on remineralization of demineralized root dentin in a cyclic artificial saliva/lactic acid environment for the first time. Methods. Root dentin specimens were prepared and demineralized with 37% phosphoric acid for 15 s. Four groups were prepared: (1) root dentin control; (2) root dentin with BMC; (3) root dentin with PAMAM; (4) root dentin with BMC + PAMAM. Specimens were treated with a cyclic artificial saliva/lactic acid regimen for 21 days. Calcium (Ca) and phosphate (P) ion concentrations and acid neutralization were determined. The remineralized root dentin specimens were examined via hardness testing and scanning electron microscopy (SEM). Results. Mechanical properties of BMC were similar to commercial control composites (p = 0.913). BMC had excellent Ca and P ion release and acid-neutralization capability. BMC or PAMAM alone each achieved slight mineral regeneration in demineralized root dentin. The combined BMC + PAMAM induced the greatest root dentin remineralization, and increased the hardness of pre-demineralized root dentin to match that of healthy root dentin (p = 0.521). Significance. The excellent root dentin remineralization effects of BMC + PAMAM were demonstrated for the first time. BMC + PAMAM induced effective and complete root dentin remineralization in an acid challenge environment. The novel BMC + PAMAM method is promising for Class V and other restorations to remineralize and protect tooth structures. PMID:28772450

Combining Bioactive Multifunctional Dental Composite with PAMAM for Root Dentin Remineralization.

PubMed

Xiao, Shimeng; Liang, Kunneng; Weir, Michael D; Cheng, Lei; Liu, Huaibing; Zhou, Xuedong; Ding, Yi; Xu, Hockin H K

2017-01-22

Objectives . The objectives of this study were to: (1) develop a bioactive multifunctional composite (BMC) via nanoparticles of amorphous calcium phosphate (NACP), 2-methacryloyloxyethyl phosphorylcholine (MPC), dimethylaminohexadecyl methacrylate (DMAHDM) and nanoparticles of silver (NAg); and (2) investigate the effects of combined BMC + poly (amido amine) (PAMAM) on remineralization of demineralized root dentin in a cyclic artificial saliva/lactic acid environment for the first time. Methods . Root dentin specimens were prepared and demineralized with 37% phosphoric acid for 15 s. Four groups were prepared: (1) root dentin control; (2) root dentin with BMC; (3) root dentin with PAMAM; (4) root dentin with BMC + PAMAM. Specimens were treated with a cyclic artificial saliva/lactic acid regimen for 21 days. Calcium (Ca) and phosphate (P) ion concentrations and acid neutralization were determined. The remineralized root dentin specimens were examined via hardness testing and scanning electron microscopy (SEM). Results . Mechanical properties of BMC were similar to commercial control composites ( p = 0.913). BMC had excellent Ca and P ion release and acid-neutralization capability. BMC or PAMAM alone each achieved slight mineral regeneration in demineralized root dentin. The combined BMC + PAMAM induced the greatest root dentin remineralization, and increased the hardness of pre-demineralized root dentin to match that of healthy root dentin ( p = 0.521). Significance . The excellent root dentin remineralization effects of BMC + PAMAM were demonstrated for the first time. BMC + PAMAM induced effective and complete root dentin remineralization in an acid challenge environment. The novel BMC + PAMAM method is promising for Class V and other restorations to remineralize and protect tooth structures.

Salt modulates gravity signaling pathway to regulate growth direction of primary roots in Arabidopsis.

PubMed

Sun, Feifei; Zhang, Wensheng; Hu, Haizhou; Li, Bao; Wang, Youning; Zhao, Yankun; Li, Kexue; Liu, Mengyu; Li, Xia

2008-01-01

Plant root architecture is highly plastic during development and can adapt to many environmental stresses. The proper distribution of roots within the soil under various conditions such as salinity, water deficit, and nutrient deficiency greatly affects plant survival. Salinity profoundly affects the root system architecture of Arabidopsis (Arabidopsis thaliana). However, despite the inhibitory effects of salinity on root length and the number of roots, very little is known concerning influence of salinity on root growth direction and the underlying mechanisms. Here we show that salt modulates root growth direction by reducing the gravity response. Exposure to salt stress causes rapid degradation of amyloplasts in root columella cells of Arabidopsis. The altered root growth direction in response to salt was found to be correlated with PIN-FORMED2 (PIN2) messenger RNA abundance and expression and localization of the protein. Furthermore, responsiveness to gravity of salt overly sensitive (sos) mutants is substantially reduced, indicating that salt-induced altered gravitropism of root growth is mediated by ion disequilibrium. Mutation of SOS genes also leads to reduced amyloplast degradation in root tip columella cells and the defects in PIN2 gene expression in response to salt stress. These results indicate that the SOS pathway may mediate the decrease of PIN2 messenger RNA in salinity-induced modification of gravitropic response in Arabidopsis roots. Our findings provide new insights into the development of a root system necessary for plant adaptation to high salinity and implicate an important role of the SOS signaling pathway in this process.

An Auxin Transport Independent Pathway Is Involved in Phosphate Stress-Induced Root Architectural Alterations in Arabidopsis. Identification of BIG as a Mediator of Auxin in Pericycle Cell Activation1

PubMed Central

López-Bucio, José; Hernández-Abreu, Esmeralda; Sánchez-Calderón, Lenin; Pérez-Torres, Anahí; Rampey, Rebekah A.; Bartel, Bonnie; Herrera-Estrella, Luis

2005-01-01

Arabidopsis (Arabidopsis thaliana) plants display a number of root developmental responses to low phosphate availability, including primary root growth inhibition, greater formation of lateral roots, and increased root hair elongation. To gain insight into the regulatory mechanisms by which phosphorus (P) availability alters postembryonic root development, we performed a mutant screen to identify genetic determinants involved in the response to P deprivation. Three low phosphate-resistant root lines (lpr1-1 to lpr1-3) were isolated because of their reduced lateral root formation in low P conditions. Genetic and molecular analyses revealed that all lpr1 mutants were allelic to BIG, which is required for normal auxin transport in Arabidopsis. Detailed characterization of lateral root primordia (LRP) development in wild-type and lpr1 mutants revealed that BIG is required for pericycle cell activation to form LRP in both high (1 mm) and low (1 μm) P conditions, but not for the low P-induced alterations in primary root growth, lateral root emergence, and root hair elongation. Exogenously supplied auxin restored normal lateral root formation in lpr1 mutants in the two P treatments. Treatment of wild-type Arabidopsis seedlings with brefeldin A, a fungal metabolite that blocks auxin transport, phenocopies the root developmental alterations observed in lpr1 mutants in both high and low P conditions, suggesting that BIG participates in vesicular targeting of auxin transporters. Taken together, our results show that auxin transport and BIG function have fundamental roles in pericycle cell activation to form LRP and promote root hair elongation. The mechanism that activates root system architectural alterations in response to P deprivation, however, seems to be independent of auxin transport and BIG. PMID:15681664

Leaf and root glucosinolate profiles of Chinese cabbage (Brassica rapa ssp. pekinensis) as a systemic response to methyl jasmonate and salicylic acid elicitation.

PubMed

Zang, Yun-xiang; Ge, Jia-li; Huang, Ling-hui; Gao, Fei; Lv, Xi-shan; Zheng, Wei-wei; Hong, Seung-beom; Zhu, Zhu-jun

2015-08-01

Glucosinolates (GSs) are an important group of defensive phytochemicals mainly found in Brassicaceae. Plant hormones jasmonic acid (JA) and salicylic acid (SA) are major regulators of plant response to pathogen attack. However, there is little information about the interactive effect of both elicitors on inducing GS biosynthesis in Chinese cabbage (Brassica rapa ssp. pekinensis). In this study, we applied different concentrations of methyl jasmonate (MeJA) and/or SA onto the leaf and root of Chinese cabbage to investigate the time-course interactive profiles of GSs. Regardless of the site of the elicitation and the concentrations of the elicitors, the roots accumulated much more GSs and were more sensitive and more rapidly responsive to the elicitors than leaves. Irrespective of the elicitation site, MeJA had a greater inducing and longer lasting effect on GS accumulation than SA. All three components of indole GS (IGS) were detected along with aliphatic and aromatic GSs. However, IGS was a major component of total GSs that accumulated rapidly in both root and leaf tissues in response to MeJA and SA elicitation. Neoglucobrassicin (neoGBC) did not respond to SA but to MeJA in leaf tissue, while it responded to both SA and MeJA in root tissue. Conversion of glucobrassicin (GBC) to neoGBC occurred at a steady rate over 3 d of elicitation. Increased accumulation of 4-methoxy glucobrassicin (4-MGBC) occurred only in the root irrespective of the type of elicitors and the site of elicitation. Thus, accumulation of IGS is a major metabolic hallmark of SA- and MeJA-mediated systemic response systems. SA exerted an antagonistic effect on the MeJA-induced root GSs irrespective of the site of elicitation. However, SA showed synergistic and antagonistic effects on the MeJA-induced leaf GSs when roots and leaves are elicitated for 3 d, respectively.

An alternative approach to extruding a vertically impacted lower third molar using an orthodontic miniscrew: A case report with cone-beam CT follow-up

PubMed Central

No-Cortes, Juliana; Cavalcanti, Marcelo Gusmão Paraíso; Arita, Emiko Saito

2014-01-01

One of the most common oral surgical procedures is the extraction of the lower third molar (LTM). Postoperative complications such as paresthesia due to inferior alveolar nerve (IAN) injury are commonly observed in cases of horizontal and vertical impaction. The present report discusses a case of a vertically impacted LTM associated with a dentigerous cyst. An intimate contact between the LTM roots and the mandibular canal was observed on a panoramic radiograph and confirmed with cone-beam computed tomographic (CBCT) cross-sectional cuts. An orthodontic miniscrew was then used to extrude the LTM prior to its surgical removal in order to avoid the risk of inferior alveolar nerve injury. CBCT imaging follow-up confirmed the success of the LTM orthodontic extrusion. PMID:24944969

An alternative approach to extruding a vertically impacted lower third molar using an orthodontic miniscrew: A case report with cone-beam CT follow-up.

PubMed

Cortes, Arthur Rodriguez Gonzalez; No-Cortes, Juliana; Cavalcanti, Marcelo Gusmão Paraíso; Arita, Emiko Saito

2014-06-01

One of the most common oral surgical procedures is the extraction of the lower third molar (LTM). Postoperative complications such as paresthesia due to inferior alveolar nerve (IAN) injury are commonly observed in cases of horizontal and vertical impaction. The present report discusses a case of a vertically impacted LTM associated with a dentigerous cyst. An intimate contact between the LTM roots and the mandibular canal was observed on a panoramic radiograph and confirmed with cone-beam computed tomographic (CBCT) cross-sectional cuts. An orthodontic miniscrew was then used to extrude the LTM prior to its surgical removal in order to avoid the risk of inferior alveolar nerve injury. CBCT imaging follow-up confirmed the success of the LTM orthodontic extrusion.

CuO Nanoparticles Inhibited Root Growth from Brassica nigra Seedlings but Induced Root from Stem and Leaf Explants.

PubMed

Zafar, Hira; Ali, Attarad; Zia, Muhammad

2017-01-01

Interests associated with nanoparticles (NPs) are budding due to their toxicity to living species. The lethal effect of NPs depends on their nature, size, shape, and concentration. Present investigation reports that CuO NPs badly affected Brassica nigra seed germination and seedling growth parameters. However, variation in antioxidative activities and nonenzymatic oxidants is observed in plantlets. Culturing the leaf and stem explants on MS medium in presence of low concentration of CuO NPs (1-20 mg l -1 ) produces white thin roots with thick root hairs. These roots also show an increase in DPPH radical scavenging activity (up to 80 % at 10 mg l -1 ), total antioxidant, and reducing power potential (maximum in presence of 10 mg l -1 CuO NPs in the media). Nonenzymatic antioxidative molecules, phenolics and flavonoids, are observed elevated but NPs concentration dependent. We can conclude that CuO NPs can induce rooting from plant explants cultured on appropriate medium. These roots can be explored for the production of active chemical constituents.

Investigating Summer Thermal Stratification in Lake Ontario

NASA Astrophysics Data System (ADS)

James, S. C.; Arifin, R. R.; Craig, P. M.; Hamlet, A. F.

2017-12-01

Seasonal temperature variations establish strong vertical density gradients (thermoclines) between the epilimnion and hypolimnion. Accurate simulation of vertical mixing and seasonal stratification of large lakes is a crucial element of the thermodynamic coupling between lakes and the atmosphere in integrated models. Time-varying thermal stratification patterns can be accurately simulated with the versatile Environmental Fluid Dynamics Code (EFDC). Lake Ontario bathymetry was interpolated onto a 2-km-resolution curvilinear grid with vertical layering using a new approach in EFDC+, the so-called "sigma-zed" coordinate system which allows the number of vertical layers to be varied based on water depth. Inflow from the Niagara River and outflow to the St. Lawrence River in conjunction with hourly meteorological data from seven local weather stations plus three-hourly data from the North American Regional Reanalysis govern the hydrodynamic and thermodynamic responses of the Lake. EFDC+'s evaporation algorithm was updated to more accurately simulate net surface heat fluxes. A new vertical mixing scheme from Vinçon-Leite that implements different eddy diffusivity formulations above and below the thermocline was compared to results from the original Mellor-Yamada vertical mixing scheme. The model was calibrated by adjusting solar-radiation absorption coefficients in addition to background horizontal and vertical mixing parameters. Model skill was evaluated by comparing measured and simulated vertical temperature profiles at shallow (20 m) and deep (180 m) locations on the Lake. These model improvements, especially the new sigma-zed vertical discretization, accurately capture thermal-stratification patterns with low root-mean-squared errors when using the Vinçon-Leite vertical mixing scheme.

Wound healing and anti-inflammatory activity of some Ononis taxons.

PubMed

Ergene Öz, Burçin; Saltan İşcan, Gülçin; Küpeli Akkol, Esra; Süntar, İpek; Keleş, Hikmet; Bahadır Acıkara, Özlem

2017-07-01

Ononis species are used for their laxative, diuretic, analgesic, anti-inflammatory, antiviral, cytotoxic and antifungal effects as well as against skin diseases for wound healing activity. In the light of this information n-hexane, ethylacetate and methanol extracts prepared from Ononis spinosa L. subsp. leiosperma (Boiss.) Sirj., Ononis variegata L., Ononis viscosa L. subsp. brevifolia (DC) Nym. and Ononis natrix L. subsp. natrix L. were tested for their wound healing, anti-inflammatory and antioxidant activities. Linear incision and circular excision wound models and hydroxypyroline estimation assay were used for the wound healing activity. For the assessment of chronic inflammation FCA-induced arthritis and for acute inflammation carrageenan-induced hind paw edema, TPA-induced ear edema and acetic acid-induced increase in capillary permeability tests were conducted. 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay, 2,2-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) scavenging activity assay, reducing power assay and hydroxyl radical (OH - ) scavenging assay were used for determining antioxidant activities of the extracts. Results showed that O. spinosa subsp. leiosperma roots ethyl acetate extract exhibited remarkable wound healing activity with the 42.6% tensile strength value on the linear incision wound model and 60.1% reduction of the wound area at the day 12 on the circular excision wound model. Hydroxyproline content of the tissue treated by O. spinosa subsp. leiosperma roots ethyl acetate extract was found to be 41.3μg/mg. Acetic acid induced increase in capillary permeability test results revealed that O. spinosa subsp. leiosperma roots ethyl acetate extract and O. spinosa subsp. leiosperma roots methanol extract inhibited inflammation by 40.4% and 35.4% values respectively. O. spinosa subsp. leiosperma roots ethyl acetate extract showed 21.2-27.2% inhibition in carrageenan-induced hind paw edema test while did not posses activity on TPA-induced ear edema and FCA-induced arthritis models. Copyright © 2017 Elsevier Masson SAS. All rights reserved.