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PubMed2004

Modelling applicability of fractal analysis to efficiency of soil exploration by roots.

BACKGROUND AND AIMS: Fractal analysis allows calculation of fractal dimension, fractal abundance and lacunarity. Fractal analysis of plant roots has revealed correlations of fractal dimension with age, topology or genotypic variation, while fractal abundance has been associated with root length. Lacunarity is associated with heterogeneity of distribution, and has yet to be utilized in analysis of roots. In this study, fractal analysis was applied to the study of root architecture and acquisition of diffusion-limited nutrients. The hypothesis that soil depletion and root competition are more closely correlated with a combination of fractal parameters than by any one alone was tested. MODEL: The geometric simulation model SimRoot was used to dynamically model roots of various architectures growing for up to 16 d in three soil types with contrasting nutrient mobility. Fractal parameters were calculated for whole roots, projections of roots and vertical slices of roots taken at 0, 2.5 and 5 cm from the root origin. Nutrient depletion volumes, competition volumes, and relative competition were regressed against fractal parameters and root length. KEY RESULTS: Root length was correlated with depletion volume, competition volume and relative competition at all times. In analysis of three-dimensional, projected roots and 0 cm slices, log(fractal abundance) was highly correlated with log(depletion volume) when times were pooled. Other than this, multiple regression yielded better correlations than regression with single fractal parameters. Correlations decreased with age of roots and distance of vertical slices from the root origin. Field data were also examined to see if fractal dimension, fractal abundance and lacunarity can be used to distinguish common bean genotypes in field situations. There were significant differences in fractal dimension and fractal abundance, but not in lacunarity. CONCLUSIONS: These results suggest that applying fractal analysis to research of soil exploration by root systems should include fractal abundance, and possibly lacunarity, along with fractal dimension.

Computer Simulation↗
PubMed2006

Dynamics of Aerenchyma distribution in the cortex of sulfate-deprived adventitious roots of maize.

BACKGROUND AND AIMS: Aerenchyma formation in maize adventitious roots is induced in nutrient solution by the deprivation of sulfate (S) under well-oxygenated conditions. The aim of this research was to examine the extent of aerenchyma formation in the cortex of sulfate-deprived adventitious roots along the root axis, in correlation with the presence of reactive oxygen species (ROS), calcium levels and pH of cortex cells and root lignification. METHODS: The morphometry of the second whorl of adventitious (W2) roots, subject to S-deprivation conditions throughout development, was recorded in terms of root length and lateral root length and distribution. W2 roots divided into sectors according to the mean length of lateral roots, and cross-sections of each were examined for aerenchyma. In-situ detection of alterations in ROS presence, calcium levels and pH were performed by means of fluorescence microscopy using H(2)DCF-DA, fluo-3AM and BCECF, respectively. Lignification was detected using the Wiesner test. KEY RESULTS: S-deprivation reduced shoot growth and enhanced root proliferation. Aerenchyma was found in the cortex of 77 % of the root length, particularly in the region of emerging or developing lateral roots. The basal and apical sectors had no aerenchyma and no aerenchyma connection was found with the shoot. S-deprivation resulted in alterations of ROS, calcium levels and pH in aerenchymatous sectors compared with the basal non-aerenchymatous region. Lignified epidermal layers were located at the basal and the proximal sectors. S-deprivation resulted in shorter lateral roots in the upper sectors and in a limited extension of the lignified layers towards the next lateral root carrying sector. CONCLUSIONS: Lateral root proliferation is accompanied by spatially localized induced cell death in the cortex of developing young maize adventitious roots during S-deprivation.

Calcium↗
PubMed2003

Biosensor reporting of root exudation from Hordeum vulgare in relation to shoot nitrate concentration.

The aim of this study was to determine the relationship between shoot nitrate concentration, mediated by nitrate supply to roots, and root exudation from Hordeum vulgare. Plants were grown for 14 d in C-free sand microcosms, supplied with nutrient solution containing 2 mM nitrate. After this period, three treatments were applied for a further 14 d: (A) continued supply with 2 mM nitrate (zero boost), (B) supply with 10 mM nitrate (low boost), and (C) supply with 20 mM nitrate (high boost). At the end of the treatment period, a bacterial biosensor (Pseudomonas fluorescens 10586 pUCD607, marked with the lux CDABE genes for bioluminescence) was applied to the microcosms to report on C-substrate availability, as a consequence of root exudation. The nitrate boost treatments significantly affected shoot nitrate concentrations, in the order C>B>A. In treatments receiving a nitrate boost (B, C), increased shoot nitrate concentration was correlated with increased plant biomass, reduced root length, reduced number of root tips, and increased mean root diameter, relative to the no boost treatment (A). Imaging of biosensor bioluminescence (proportional to metabolic activity in response to availability of root exudates) indicated that root exudation increased with decreasing shoot nitrate concentration. Biosensor reporting of root C-flow indicated that exudation was greater from root tip regions than from the whole root, but that specific exudation rates for all sites were unaffected by treatments. Total root exudation across treatments was found to be closely correlated with total root length, indicating that increased root exudation, per unit root biomass, with decreasing nitrate supply was associated with altered root morphology, as a consequence of systemic plant responses to internal N-status.

Biomass↗
PubMed2003

Interaction between two auxin-resistant mutants and their effects on lateral root formation in rice (Oryza sativa L.).

Since root elongation is very sensitive to auxin, screening for reduced inhibition in root elongation has been an important method for the detection of auxin-resistant mutants. Two recessive auxin-resistant lines of rice (Oryza sativa L. ssp. indica cv. IR8), arm1 and arm2, have been isolated by screening for resistance to 2,4-dichlorophenoxyacetic acid (2,4-D). arm1 displays a variety of morphological defects including reduced lateral root formation, increased seminal root elongation, reduced root diameter, and impaired xylem development in roots, while the arm2 phenotype is almost similar to wild-type IR8 except for a slightly reduced lateral root formation, impaired xylem development in roots and an enhanced plant height. Although the growth of arm2 roots exhibited a resistance to 2,4-D, it was sensitive to 1-naphthaleneacetic acid (NAA) as the wild type. At the same time, the arm2 roots showed a reduced [14C]2,4-D uptake while uptake of [3H]NAA was normal, suggesting that the resistance to 2,4-D of arm2 roots is due to a defect in 2,4-D uptake. To investigate the possible interaction between arm1 and arm2 genes, a double mutant has been constructed. The roots of arm1 arm2 double mutant were more resistant to 2,4-D and formed fewer lateral roots than those of either single mutant, suggesting that the two genes show synergistic effects with respect to both auxin response and lateral root formation. By contrast, all these mutants displayed the normal gravitropic response in roots, as did the wild-type plants. Taken together, Arm1 and Arm2 genes seem to function in different processes in the auxin-response pathways leading to lateral root formation.

2,4-Dichlorophenoxyacetic Acid↗
PubMed2006

Root turnover and relocation in the soil profile in response to seasonal soil water variation in a natural stand of Utah juniper (Juniperus osteosperma).

Juniper species are noted for long-lived foliage, low and persistent gas exchange activity and drought tolerance. Because leaves and roots of the same species are thought to be similar in structure and life history, we hypothesized that Juniperus osteosperma (Torr.) Little (Utah juniper) fine roots would reflect the persistent aboveground foliage characteristic of this species. We monitored fine roots, less than 1 mm in diameter, by minirhizotron imaging to a depth of 150 cm over two growing seasons from April 2002 to December 2003. We measured fine root numbers, lengths and diameters, and noted the time of birth and death of root segments. We correlated our root data with soil water potential measured by thermocouple psychrometry and ecosystem evapotranspiration measured by ecosystem eddy flux. Median fine root lifespan, determined by the Kaplan-Meier product-limit method, was about one year, much less than foliage lifespan estimates of more than five years. Yet, roots of juniper live much longer than those of other Great Basin species. The median survivorship of shallow and deep roots was 144 and 448 days, respectively. Production of new roots was observed during periods of favorable soil water potential and there was a seasonal progression of increased new roots and root length during the warm season toward lower soil depths with root loss in the upper soil layers. This was also reflected in water extraction which progressed to greater soil depths later in the warm season. Aboveground, rates of ecosystem evapotranspiration decreased with decreasing soil water potentials in a similar manner in both 2002 and 2003, reflecting the relocation of roots to available water at depth. Juniper exhibited a flexible root depth distribution throughout the 20 months of this study, indicating the potential to respond to shifting soil water resources despite long fine root lifespans.

Climate↗
PubMed1995

Physiologic changes of nerve root during posterior lumbar discectomy.

STUDY DESIGN AND OBJECTIVES: The effects of nerve root retraction in posterior discectomy on pressure, blood flow, and electrophysiologic changes of the nerve root were investigated. OBJECTIVES: This study was performed to assess the effects of nerve root retraction in posterior discectomy on pressure, blood flow, and electrophysiologic changes of the nerve root. SUMMARY OF BACKGROUND DATA: The effects of compression on nerve tissue have been clinically studied mainly in peripheral nerves. The potential risk for lumbar nerve root injury has not been evaluated precisely in humans. METHODS: Among 31 patients with lumbar intervertebral disc herniation, the correlation between retraction pressure and changes in blood flow of the nerve root was evaluated. Retraction pressure was continuously monitored during the discectomy and the length of the discectomy procedure was measured. Threshold and amplitude of compound muscle action potentials were monitored before and after discectomy. The relationship between intraoperative data on nerve root physiology and postoperative neurologic change was analyzed. RESULTS: Nerve root blood flow was decreased to 18-30% of the initial value under the pressure around 70 g/cm2. An abrupt decrease in nerve root blood flow was observed even within 1 or 2 mm of retraction distance. The threshold of the nerve root before retraction was minimal in the nerve root of the asymptomatic side, but increased in the affected root demonstrating sensory loss only, and significantly increased in the root showing sensory/motor deficit. Amplitude of compound muscle action potentials evoked by the stimulation at distal from herniated mass was lowest in the nerve root showing sensory/motor deficit. In 4 of 31 patients, high retraction pressure (> 170 g/cm2) was required and they showed temporary sensory deterioration after surgery. The length of discectomy procedure in these 4 patients was 14.1 +/- 4.1 minutes, but it was 9.9 +/- 2.7 minutes in the remaining 27 patients. CONCLUSIONS: In posterior lumbar discectomy, nerve root ischemia usually occurs during retraction. The magnitude of pressure and time of retraction may be potential risk factors for nerve root injury.

Adolescent↗
PubMed2000

Electrical thresholds for biomechanical response in the ankle to direct stimulation of spinal roots L4, L5, and S1. Implications for intraoperative pedicle screw testing.

STUDY DESIGN: A comparison of electrical thresholds for biomechanical response in the ankle and for evoked electromyographic signals from specific leg muscles during intraoperative extradural direct stimulation of roots L4, L5, and S1. OBJECTIVE: To determine whether a biomechanical response in the ankle to direct root stimulation occurs before evoked electromyographic signals and to determine differences in electrical excitability of the roots circumferentially. SUMMARY OF BACKGROUND DATA: Stimulus intensities of 1.2-5.7 mA are reported to evoke electromyographic response in corresponding muscles to direct stimulation of normal roots. Stimulus intensities of 6-8 mA were suggested to detect bony pedicular compromise by stimulation of a hole or a screw during pedicle instrumentation. Electrical thresholds of three-dimensional torque response in the ankle to direct root stimulation have not yet been evaluated and compared with thresholds of evoked electromyogram. METHODS: Direct monopolar stimulation of the surgically exposed roots L4, L5, and S1 was performed from different sites around the root by a cuff multielectrode. Biomechanical response was measured as an isometric torque in the ankle at each of three orthogonal axes. Compound muscle action potentials (CMAPs) from root-specific muscles were detected by a pair of surface or wire electrodes. RESULTS: Mean threshold for biomechanical response in the ankle to stimulation of roots L4, L5, and S1 was 0.72 +/- 0.39 mA and for CMAP response was 1.09 mA +/- 0.36 (N = 13). Thresholds for biomechanical responses were significantly lower than for CMAP responses (P = 0.0004; paired t test). Nerve roots were electrically most excitable on their ventral aspects. CONCLUSION: The biomechanical response in the joint to root stimulation can be used to test all root-related muscles crossing that joint at their individual innervation pattern and their residual innervation and to detect electrical excitation of the root at electric thresholds lower than those for detecting CMAP from single standard root-specific muscle. However, this method does not provide sufficient root specificity. It will be valuable in conjunction with multimodality neurophysiologic monitoring of the roots for earlier and more reliable detection of pedicle bone breakthrough or integrity. Further clinical investigations are suggested.

Ankle↗
PubMed2006

Intraoperative electrophysiologic studies on the functions of nerve roots involved in cervical dumbbell-shaped schwannoma and their clinical utility.

BACKGROUND: It is difficult to expect the degree of neurologic deficits after resection of involved nerve roots before and during the surgery for cervical dumbbell-shaped schwannoma. We present the results of studies for cervical nerve root functions in patients with cervical schwannoma using intraoperative electrophysiologic assessment and the potential of their clinical relevance is also discussed. OBJECTIVE: To present the utility of intraoperative electrophysiologic studies to detect the functions of the nerve roots involved in cervical schwannoma and adjacent nerve roots. METHODS: Five patients with dumbbell-shaped cervical schwannoma arising from the cervical nerve roots composing the brachial plexus were studied. Compound muscle action potentials (CMAPs) after stimulation of nerve roots involved in the schwannoma were recorded from upper limb muscles anatomically correspond to their myotome. Adjacent nerve roots were also stimulated. Motor-evoked potentials (MEPs) after transcranial electric stimulation were also recorded during surgery. In 3 patients, sensory nerve action potentials (SNAPs) after digital nerve stimulation were also recorded from cervical nerve roots. RESULTS: In 4 patients, CMAPs after stimulation of cervical nerve roots involved with the schwannoma were not obtained or were very small compared with those obtained after stimulation of adjacent nerve roots. In 2 of 4 patients, SNAPs after digital nerve stimulation were recorded with small amplitude from the nerve roots involved in schwannoma. Minimal (n=2, within 80% attenuation of amplitude) or no changes (n=2) were observed after total resection of the schwannoma and no apparent motor weakness occurred in these 4 patients. In a patient with cervical schwannoma involved in C8 nerve root, CMAPs with large amplitude were recorded after stimulation of the C8 nerve root. SNAPs after stimulation of digit V were recorded with larger amplitude from the T1 root compared with those recorded from the C8 nerve root. Intradural parts of the tumor arising from C8 posterior rootlets were completely removed after transaction of posterior rootlets. During removal of intraforaminal parts of the tumor, motor evoked potentials were decreased over 50% of controls. Incomplete removal was chosen to avoid deterioration of motor function. Transient dysesthesia of digit V and slight weakness occurred after surgery. CONCLUSIONS: The residual function of motor and sensory nerve roots involved with cervical schwannoma differed between individuals and could be detected using intraoperative electrophysiologic assessment.

Action Potentials↗
PubMed2006

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

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.

Circadian Rhythm↗
PubMed2004

Mutation of a UDP-glucose-4-epimerase alters nematode susceptibility and ethylene responses in Arabidopsis roots.

In Arabidopsis, mutation of RHD1, a UDP-glucose-4-epimerase, causes root-specific phenotypes, including hypersusceptibility to the cyst nematode Heterodera schachtii, increased root hair elongation, decreased root length, and root epidermal bulging. Previous experiments suggested that increased ethylene sensitivity or production mediated the rhd1-4 phenotypes. In the present study, double mutant analyses revealed that only rhd1-4 hypersusceptibility to H. schachtii and increased root hair elongation were dependent upon the ethylene signaling genes EIN2 and EIN3 but not upon ethylene signaling mediated by the auxin efflux carrier EIR1. In contrast, the rhd1-4 short root and root epidermal bulging phenotypes did not require EIN2, EIN3, or EIR1. A time-course analysis of RHD1 transcript levels in wild-type plants treated with the ethylene precursor 1-aminocyclopropane-1-carboxylic acid showed a root-specific downregulation of RHD1 expression by ethylene. This observation was corroborated by our finding of increased RHD1 transcript levels in roots of the ethylene-insensitive mutants etr1 and ein2. In addition to ethylene, auxin strongly influences H. schachtii susceptibility and root hair elongation. Therefore, we investigated the sensitivity of rhd1-4 roots to indole-3-acetic acid (IAA). Equivalent IAA concentrations caused a greater reduction in rhd1-4 root elongation compared with wild-type roots. Finally, H. schachtii parasitism was found to strongly downregulate RHD1 expression in the root 3 days after inoculation. We conclude that RHD1 is a likely target of root-specific negative regulation by ethylene and that loss of RHD1 function results in a heightened sensitivity of root tissues to both ethylene and auxin.

Amino Acids, Cyclic↗
PubMed1986

Afferent fibres in cat ventral roots: electrophysiological and histological evidence.

Electrophysiological experiments using averaging techniques, as well as anatomical experiments using horseradish peroxidase staining, have provided further evidence of afferent axons in lumbosacral ventral roots of cats. Recording from dorsal root filaments in L7, S1 or S2, following stimulation of the companion ventral root close to the dura, often shows action potentials of slow conduction velocity belonging to the A delta or C group. Stimulation applied to the proximal part of the ventral root failed to evoke such responses. Recording from multiple sites along a centrally cut ventral root filament shows responses of two types: action potentials of long latency to peripheral nerve stimulation which are seen at all recording locations and which are not seen following dorsal root stimulation. These appear to be afferent fibres which enter the cord via the ventral root; action potentials which follow dorsal root stimulation and which are usually seen only at the most distal ventral root recording site. Some of these were also activated by stimulation of some skin or muscle nerves. At appropriate intervals collision of impulses from dorsal root or peripheral nerve can be demonstrated. Such axons appear to have a recurrent course in the ventral root. Section of the spinal nerve at points progressively closer to the dorsal root ganglion abolishes the dorsal to ventral root continuity of most recurrent type axons at 2 mm distal to the ganglion. Following application of horseradish peroxidase to crushed ends of distal stumps of cut dorsal roots, thin fibres marked by the enzyme are observed in the distal part of companion ventral roots. U-turns of axons have been observed in the distal part of ventral roots and in the spinal nerve near the pole of the ganglion.

Action Potentials↗
PubMed2003

Genetic analysis of adventitious root formation with a novel series of temperature-sensitive mutants of Arabidopsis thaliana.

When cultured on media containing the plant growth regulator auxin, hypocotyl explants of Arabidopsis thaliana generate adventitious roots. As a first step to investigate the genetic basis of adventitious organogenesis in plants, we isolated nine temperature-sensitive mutants defective in various stages in the formation of adventitious roots: five root initiation defective (rid1 to rid5) mutants failed to initiate the formation of root primordia; in one root primordium defective (rpd1) mutant, the development of root primordia was arrested; three root growth defective (rgd1, rgd2, and rgd3) mutants were defective in root growth after the establishment of the root apical meristem. The temperature sensitivity of callus formation and lateral root formation revealed further distinctions between the isolated mutants. The rid1 mutant was specifically defective in the reinitiation of cell proliferation from hypocotyl explants, while the rid2 mutant was also defective in the reinitiation of cell proliferation from root explants. These two mutants also exhibited abnormalities in the formation of the root apical meristem when lateral roots were induced at the restrictive temperature. The rgd1 and rgd2 mutants were deficient in root and callus growth, whereas the rgd3 mutation specifically affected root growth. The rid5 mutant required higher auxin concentrations for rooting at the restrictive temperature, implying a deficiency in auxin signaling. The rid5 phenotype was found to result from a mutation in the MOR1/GEM1 gene encoding a microtubule-associated protein. These findings about the rid5 mutant suggest a possible function of the microtubule system in auxin response.

Arabidopsis↗
PubMed2004

[Root growth dynamics of Adenophora potaninii populations and its relation with environmental factors in northwest Sichuan Province].

In this paper, the dynamics of the root biomass and form development of Adenophora potaninii populations in different natural habitats in Northwest Sichuan were studied, and the factors influencing the root growth and form development were analyzed. The root biomass accumulation process of the mean individuals of the whole A. potaninii population in its life could be expressed by Logistic equation. From 1-3 years, the root length grew fast, but the root biomass accumulated slowly. From 4 years old, the root system developed in high speed, and the fast growth period of the root system could maintain until 15 year old. The basic patterns of root biomass accumulation process of different A. potaninii populations at different altitudes were similar to that of the whole population. However, the root system accumulation and root development was related closely with habitant conditions, and the root forms of different populations at different altitudes were significantly different (P < 0.05). At middle altitude (2800-3300 m), the biomass and form of root system could achieve a higher level, and the good harvest of root biomass could be obtained because of the favorable soil and climate conditions, and the less external disturbance of human beings. Therefore, this area could be an important base for A. potaninii population to grow. Whereas at the lower altitude (2600-2800 m), the biomass accumulation and the form development of root system were confined and maintained at a lower level because of the drought climate and the external disturbance of human beings. At the higher altitude (3300-3500 m) area with the harsh habitats, especially with lower temperature and lower pH, the root biomass of the mean individuals was significantly lower, and the individual form of root system was smaller, compared with that at middle altitude area. In order to use natural A. potaninii resource sustainablely, all the area should be planned, and the reasonable rotational prohibition of grazing and digging should be carried out.

Altitude↗
PubMed2006

[Effects of light and plant growth regulators on growth of normal and hairy root of Lycium barbarum in vitro].

OBJECTIVE: To study effects of the cycle of light and exogenous plant growth regulators on growth of normal root and hairy root of Lycium barbarum and establish a long-term system of in vitro culture of L. barbarum roots. METHOD: Using normal roots from aseptic seedlings and hairy roots originated from Agrobacterium rhizogenes A4-mediated genetic transformation of L. barbarum, the growth of root segments was examined after 20 days of culture under different culture conditions. RESULT AND CONCLUSION: When cultured on the MS medium with different plant growth regulators (IAA, IBA, NAA), normal root segments of L. barbarum could elongate and branch, and the addition of 1 mg x L(-1) IBA into the medium was the most suitable for long-term in vitro culture of L. barbarum root. When cultured on MS medium without hormone, light promoted the elongation and lateral root formation of type II hairy root, but not of type I hairy root. Among three tested hormones, IAA at low concentration was the best for growth of type I hairy root, while 1 mg x L(-1) IBA was the most suitable for growth of type II hairy root. With the increase of hormone level added into MS medium, callusing frequencies of type I, II hairy roots were increased, at the same time, the formation of lateral root from hairy root or callus was inhibited.

Culture Media↗
PubMed2006

[Application of minirhizotron in fine root studies].

Due to the production, death, and decomposition of fine root, its turnover plays an important role in carbon allocation and nutrient cycling in terrestrial ecosystems. Some methods such as sequential root coring, compartmental flow model, and ingrowth core have been widely used in collecting root biomass data and estimating fine root turnover, but failed in monitoring the dynamics of fine root due to its simultaneous production and death. Minirhizotron is a nondestructive in situ method for studying the dynamics of fine root, which allows the simultaneous measurement of fine root growth and mortality. This paper reviewed the application of minirhizotron in fine root studies, with the focus on minirhizotron tube installation, image collection, data extraction, and calculation parameters. In a case study, the total fine root length, fine root length density per unit volume, fine root length density per unit area, fine root biomass density, and fine root production and mortality of Fraxinus mandshurica and Larix gmelini were calculated, and the results showed that minirhizotron method was feasible in studying the processes of fine root development, eclipse, death, and decomposition. The factors affecting fine root measurement and its precision mainly included the quality and quantity of tube installation, sampling interval and quantity, and analysis technique of images, etc. Soil texture, tube material, and disturbance of light on root were also the factors affecting the precision of the method. How to improve the measurement precision of minirhizotron would be the critical problem in future study.

Fraxinus↗
PubMed2003

Effect of enamel matrix proteins (Emdogain') on healing after re-implantation of "periodontally compromised" roots. An experimental study in the dog.

OBJECTIVE: The present experiment was performed to assess whether Emdogain applied on the root surface of extracted teeth or teeth previously exposed to root planning can protect the tooth from ankylosis following re-implantation. MATERIAL AND METHODS: The experiment included two groups of dogs, including five animals each. The root canals of all mandibular third premolars (3 P 3) were reamed and filled with gutta-percha. A crestal incision was placed from the area of the second to the fourth premolar. Buccal and lingual full thickness flaps were elevated. With the use of a fissure bur, the crown and furcation area of 3 P 3 were severed in an apico-coronal cut. The distal and mesial tooth segments were luxated with an elevator and extracted with forceps. Group A: The mesial and distal segments of 3 P 3 were air dried on a glass surface for 60 min. The roots from the right side were conditioned and exposed to Emdogain application. The roots from the left side received the same treatment with the exception of Emdogain application. The mesial and distal tooth segments were re-implanted and the crown portions were severed with a horizontal cut and removed. The buccal and lingual flaps were mobilized and sutured to obtain complete coverage of the submerged roots. Group B: A notch was prepared in each root, 4-5 mm apical of the cemento-enamel junction. The area of the root that was located coronal to the notch was scaled and planned. The roots in the right side of the mandible were treated with Emdogain, while the roots in the left side served as controls. After 6 months of healing, the dogs were killed and blocks containing one root with surrounding tissues were harvested, and prepared for histological examination, which also included morphometric assessments. Thus, the proportions of the roots that exhibited signs of (i) replacement (ii) inflammatory and (iii) surface resorption were calculated. RESULTS AND CONCLUSION: It was demonstrated that healing of a re-implanted root that had been extracted and deprived of vital cementoblasts was characterized by processes that included root resorption, ankylosis and new attachment formation. It was also demonstrated that Emdogain treatment, i.e. conditioning with EDTA and placement of enamel matrix proteins on the detached root surface, failed to interfere with the healing process.

Animals↗
PubMed2001

Root and canal morphology of Burmese maxillary molars.

AIM: To investigate the root and canal morphology of Burmese maxillary molars using a canal staining and tooth clearing technique. METHODOLOGY: Maxillary molars (239) were collected from indigenous Burmese patients and designated; first (90), second (77), third (72) molars. Following pulp tissue removal and canal system staining with Indian ink, the teeth were decalcified with 10% nitric acid, dehydrated and cleared with methyl salicylate. The following features were evaluated: (i) number of roots and morphology; (ii) number of canals per root: (iii) root canal configuration (Vertucci's classification); (iv) number of apical foramina per root; (v) number and location of lateral canals; and (vi) the presence of intercanal communications. RESULTS: All first and second molars had three separate roots, whilst third molars had one of five different root forms, of which three separate (25%) or fused (31%) roots were most prevalent. The majority of palatal (100%) and disto-buccal (96%) roots possessed one canal (type I). The prevalence of mesio-buccal roots with two canals decreased from first to third molars (68%, 49%, 39%, respectively); type II (two orifices, one apical foramen) and IV (two orifices, two apical foramina) configurations were the most common. Single/fused rooted third molars had a range of number and type of canals. Most roots in all molars had one apical foramen, those with four apical foramina were confined to third molars. Intercanal communications were most prevalent in mesio-buccal roots and two/three fused rooted third molars. Lateral canals were most prevalent in the apical third of the roots of all molars. CONCLUSIONS: The mesio-buccal roots of Burmese maxillary molars possessed a variety of canal system types. Over 50% of the first and second molars had a second mesio-buccal canal, of which over 20% had intercanal communications. The palatal and disto-buccal canals mainly had type I canals. Lateral canals were equally prevalent in all tooth types but were most common in the apical third.

Adult↗
PubMed1995

Arbuscular mycorrhizal induced changes to plant growth and root system morphology in Prunus cerasifera.

We compared root system morphogenesis of micropropogated transplants of Prunus cerasifera L. inoculated with either of the arbuscular mycorrhizal (AM) fungi Glomus mosseae or Glomus intraradices or with the ericoid mycorrhizal species Hymenoscyphus ericae. All plants were grown in sand culture, irrigated with a nutrient solution that included a soluble source of phosphorus, for 75 days after transplanting. Arbuscular mycorrhizal colonization increased both the survival and growth (by over 100%) of transplants compared with either uninoculated controls or transplants inoculated with H. ericae. Arbuscular mycorrhizal colonization increased root, stem and leaf weights, leaf area, root length and specific leaf area, and it decreased root length/leaf area ratio, root/shoot weight ratio and specific root length. Both uptake of phosphorus and its concentration in leaves were increased by AM infection, although the time course of the relationships between intensity of AM infection and P nutrition were complex and suggested a role for factors other than nutrition. The time course for the development of infection varied. It was most rapid with G. mosseae, but it was ultimately higher with G. intraradices. None of the treatments significantly affected the lengths of adventitious roots or the first-, second- or third-order laterals that developed from them. Arbuscular mycorrhizal colonization increased the intensity of branching in all root orders with the effect being most obvious on first-order lateral roots where the number of branches increased from under 100 to over 300 brances m(-1). As a result, although first-order laterals made up 55% of the root systems of control plants, the comparable value was 36% in AM-infected plants. In contrast, second-order laterals represented 25% of control root systems, but 50% of AM-colonized root systems. Glomus intraradices but not G. mosseae increased root diameter. Anatomical studies revealed no changes in the overall form of the root tip, although there were changes in the diameter of the root cap, cell numbers and cell size. Hymenoscyphus ericae increased the duration of the metaphase index. Both AM fungal treatments increased the concentrations of soluble proteins in root extracts and modified the protein profiles by the elimination and addition of protein bands detected by PAGE analysis. We conclude that AM fungal inoculation influenced processes in the root system at different levels, but not all effects were due to improved P nutrition or increased physiological age.

Journal Article↗