Immature Root Research Articles

Nuclear import of Agrobacterium VirD2 and VirE2 proteins in maize and tobacco.

Previously, we have shown that Agrobacterium-plant cell transferred DNA (T-DNA) transport into the host cell nucleus is likely mediated by two specific bacterial proteins, VirD2 and VirE2. Here, we used these proteins to study molecular pathways of nuclear import. First, the role of VirE2 nuclear localization signals (NLSs) in the T-DNA transport pathway was examined by using tobacco plants transgenic for deletion mutants of VirE2. In these plants, the virulence of wild-type Agrobacterium was reduced possibly by competition for the cellular nuclear import machinery. Second, we analyzed the nuclear localization of VirE2 and VirD2 in the nonhost monocot maize. Part of the known recalcitrance of monocots to transformation by Agrobacterium could be due to a potential selectivity in nuclear import pathways in monocotyledonous and dicotyledonous plants. Nuclear transport of VirD2 and VirE2 in maize leaves and roots was compared to that in tobacco protoplasts and roots. Both proteins accumulated in maize leaf and tobacco protoplast nuclei as well as in nuclei of immature root cells. In contrast, VirD2 and VirE2 expressed in mature roots of maize and tobacco remained cytoplasmic. Point mutations of VirE2 nuclear localization signals, NSE 1 and NSE 2, also revealed that, in maize, the NSE 1 signal was mainly responsible for nuclear import; in contrast, both signals functioned independently in tobacco protoplasts.

Comparison of phosphoprotein isolated from mature and immature human tooth roots

Mature (average patient age = 29.5 yr, closed apical foramen) and immature (average patient age = 17.5 yr, open apical foramen) root shards were placed in dialysis tubing and demineralized to completion using either 10% disodium EDTA plus protease inhibitors or 0.6 N HCl. The demineralized shards were re-extracted (five times) with 0.05 M tris-HCl, 1.0 M NaCl and then collagenase digested. No major differences were observed in chromatograms of extracts, re-extracts or collagenase digests from root shards demineralized in either way. In contrast, chromatograms of immature and mature roots showed qualitative differences. Chromatograms of mature roots demineralized in either way showed broader protein peaks and less organic phosphorus than those from immature tooth roots. A distinct band amid degraded phosphoprotein (150 K) was found in SDS-PAGE gels (7.5%) from EDTA-extracted immature tooth roots but not from mature tooth roots. Electroelution of this band revealed a typical phosphoprotein amino-acid profile containing increased aspartic acid and serine residues. Comparison of the total phosphoprotein and amino acid composition of extracts, re-extracts and collagenase digests revealed that phosphoprotein, serine and to a lesser extent aspartic acid were recovered in greater quantities from immature roots than mature tooth roots. These data suggest that the degree of maturation is crucial to the isolation of an intact phosphoprotein and provides additional evidence that human dentine phosphoprotein undergoes amino acid compositional changes during maturation.

Traumatically intruded permanent incisors: a study of treatment and outcome

Twenty-nine traumatically intruded permanent maxillary incisors from 20 patients were examined, treated and monitored for 2 years. There was a higher proportion of males than females. The teeth intruded furthest were more frequently extracted. Those which were surgically repositioned were more frequently retained and were associated with marginal bone loss significantly less frequently than those which were passively observed, while external root resorption occurred in similar proportions in both groups. A significantly higher proportion of those teeth that were delayed in presentation were subsequently extracted, and a similar trend was found for those with immature roots at the time of the initial examination.

Developmental and environmental regulation of a bean chalcone synthase promoter in transgenic tobacco.

Regulatory properties of a 1.4-kilobase promoter fragment of the bean chalcone synthase CHS8 gene were examined by analysis of glucuronidase (GUS) activity in transgenic tobacco containing a CHS8-GUS gene fusion. The promoter was highly active in the root apical meristem and in petals, exclusively in those cells of the inner epidermis that accumulate anthocyanins. The gene fusion was only weakly expressed in other floral organs, mature leaves, and stems. The early stages of seedling development were characterized by an apparent wound induction of the promoter in the endosperm and strong expression in the immature root, which became localized to the apical meristem and perivascular tissue at the root-hypocotyl junction. The promoter became active during lateral root formation in both the new root and damaged tissue of the main root. The gene fusion was also expressed in greening cotyledons and primary leaves but not in the shoot apical meristem. Light modulated expression in the cotyledons and root-shoot junction but had no effect on other aspects of the developmental program. Wounding or fungal elicitor treatment of mature leaves activated the promoter in a well-defined zone adjacent to the stress site. Stress induction occurred in mesophyll and vascular tissues as well as in the epidermis. We conclude that the CHS8 promoter contains cis-elements required to establish temporal and spatial control of flavonoid biosynthesis during development and in response to diverse environmental stimuli.

The effect of ultrasonic endodontics on the temperature of the root canal wall

Ultrasonic endodontics, with either a continuous flow of irrigant or an intermittent irrigant flush, was carried out on teeth with a mature or immature root canal wall. Temperature changes were measured with thermocouples placed inside the root canal and on the external root surface. A continuous flow of irrigant caused the external temperature to fall from 37°C to 32°C. In the intermittent technique a temperature peak of 45°C was recorded internally and 40°C at the external root surface. The thickness of the root canal wall had an effect on the rate of temperature change rather than the final temperature. Ultrasonic endodontics, with either a continuous flow of irrigant or an intermittent irrigant flush, was carried out on teeth with a mature or immature root canal wall. Temperature changes were measured with thermocouples placed inside the root canal and on the external root surface. A continuous flow of irrigant caused the external temperature to fall from 37°C to 32°C. In the intermittent technique a temperature peak of 45°C was recorded internally and 40°C at the external root surface. The thickness of the root canal wall had an effect on the rate of temperature change rather than the final temperature.

Evidence for the Presence of a Sucrose Carrier in Immature Sugar Beet Tap Roots

The objectives of this work were to determine the path of phloem unloading and if a sucrose carrier was present in young sugar beet (Beta vulgaris L.) taproots. The approach was to exploit the characteristics of the sucrose analog, 1'-fluorosucrose (F-sucrose) which is a poor substrate for acid invertase but is a substrate for sucrose synthase. Ten millimolar each of [(3)H]sucrose and [(14)C]F-sucrose were applied in a 1:1 ratio to an abraded region of an attached leaf for 6 hours. [(14)C]F-sucrose was translocated and accumulated in the roots at a higher rate than [(3)H]sucrose. This was due to [(3)H]sucrose hydrolysis along the translocation path. Presence of [(3)H]hexose and [(14)C]F-sucrose in the root apoplast suggested apoplastic sucrose unloading with its subsequent hydrolysis. Labeled F-sucrose uptake by root tissue discs exhibited biphasic kinetics and was inhibited by unlabeled sucrose, indicating that immature roots have the ability for carrier-mediated sucrose transport from the apoplast. Collectively, in vivo and in vitro data indicate that despite sucrose hydrolysis by the wall-bound invertase, sucrose hydrolysis is not entirely essential for sugar accumulation in this tissue.

The use of 4 per cent sodium hypochlorite, with or without ultrasound, in cleansing of uninstrumented immature root canals; SEM study.

AbstractBarbed broaches were used to remove the intact pulp from freshly extracted, single rooted, human first bicuspid teeth with an immature apex. The efficiency of 4 per cent sodium hypochlorite in the removal of soft tissue and predentine from the root canal wall was assessed using the scanning electron microscope. Four per cent sodium hypochlorite was found to be an efficient protein solvent in these wide canals, and this efficiency was increased by using ultrasound to activate the sodium hypochlorite solution. After 3 minutes exposure to the 4 per cent sodium hypochlorite/ultrasound combination, the root canal surface was free from pulpal debris and predentine. The presence of calcospherites on the root canal wall indicated that the debridement had been achieved without the loss of any of the calcified root canal wall thickness.

The occurrence and properties of alkaline invertase in mature roots of sugar beets.

Alkaline invertase activity was hardly detectable in immature sugar beet roots, but appeared when the roots began to develop and simultaneouly to synthesize sucrose, and thereafter, increased parallel with sucrose accumulation. Conversely, acid invertase activity was very high in immature roots, but rapidly decreased before sucrose was stored, and was hardly detectable in mature roots.Alkaline invertase was partially purified from mature roots by procedures including ammonium sulfate fractionation, DEAE-cellulose column chromatography, Sephacryl S-300 gel filtration, and ECTEOLA-cellulose column chromatography. Alkaline invertase consisted of two forms (enzymes I and II) which were separated by DEAE-cellulose column chromatography. Relative molecular weights of both enzymes obtained by gel filtration on Sephacryl S-300 were the same, and were estimated to be 280,000. Their pH optima were in the vicinity of 8.0. The Km value for sucrose of enzyme I was 33.3 mm and enzyme II showed a biphasic curve in Linew...

The use of sodium hypochlorite activated by ultrasound for the debridement of infected, immature root canals

Four percent sodium hypochlorite activated by ultrasound was the only instrumentation used to remove debris from necrotic, immature root canals. The effectiveness of this irrigation technique produced conditions favorable for an apexification technique utilizing calcium hydroxide paste. The stability of the apical hard tissue bridge was confirmed at recall periods of up to 4 yr.

Replantation of avulsed teeth with immature root development

Successful treatment of the avulsed tooth with immature root development is dependent on both pulpal and periodontal responses. The pulpal reaction is often one of revascularization with subsequent replacement of the necrotic pulp tissue. Continued root development and further calcification of the existing root structure are often seen with revitalization. The periodontal response to avulsion is dependent on the vitality of the periodontal ligament cells on the root surface. Normal healing occurs when the vitality is maintained, while replacement resorption results when the vitality is lost. Replantation after a short extra-alveolar period appears to provide the best prognosis for long-term retention of the avulsed tooth.

The effect of apicoectomy before replantation on periodontal and pulpal healing in teeth in monkeys

The effect of resection of the apical part of the root before replantation upon periodontal and pulpal healing was studied in 7 green Vervet monkeys ( Cercopithecus aethiops) using teeth with incomplete and complete root formation. Maxillary central incisors, mandibular lateral incisors and first and second mandibular molars were used in this experiment. On one side, the tooth was extracted and replanted with an intact root while the contralateral tooth had 2 mm of the apex resected for the purpose of facilitating pulpal repair and eliminating resorption in the resorption-prone region of the root. The replanted teeth were examined histologically 8 weeks after replantation. The histometric analysis revealed no significant difference in periodontal healing between teeth with or without apical resection. With regard to pulpal healing, apical resection was found to lead to significantly less vital pulp tissue in teeth with immature root formation. A similar, but not significant difference was found for mature teeth. Based on these findings, it could not be recommended that apices be resected prior to replantation in order to improve pulpal repair.

Root hair deformation in the white clover/Rhizobium trifolii symbiosis

Rhizobium trifolii most frequently infects its host white clover (Trifolium repens L.) by means of infection threads formed in markedly curled root hairs. Rhizobium infections are classified as either lateral or apical based on whether they originate in the branches or at the apex of the root hairs. A quantitative estimate of lateral and apical infection in the region of the host root (Trifolium repens L. cv. Regal Ladino) that possessed mature and immature root hairs at the time of inoculation with Rhizobium trifolii TAI (CSIRO, Canberra City, Australia) indicated that lateral infection occurred more frequently in the mature root hair region of the root. Apical infections were more common in the immature root hair region. Cell free filtrates collected from R. trifolii cultured in association with the host roots induced branching in white clover root hairs. A partially purified preparation of the branching factor was obtained from freeze‐dried filtrates by ethanol extraction and ion exchange chromatography. Preliminary studies on the characteristics of these substances suggest that some are dialyzable and heat stable white others are non‐dialyzable and heat labile. The dialyzable, heat‐stable compounds contain neutral sugars and range between 1200 to 10000 daltons in size. In roots that were exposed to low concentrations (6–25 μg‐ml−1) of these partially purified deformation factors before inoculation, the developmentally mature root hairs were deformed at the time of inoculation. Nodules appeared in the mature and immature root hair region of these plants at the same time. In plants exposed to water, nodules were observed in the immature root hair region and mature root hair regions 3 and 5 days after inoculation, respectively. Based on these results, we conclude that the nodule development was hastened in the plants exposed to the root hair‐deforming substances because the mature root hairs of these plants were made infectible at the time of inoculation by this exposure.

Influence of root development on periodontal and pulpal healing after replantation of incisors in monkeys

The influence of root development on periodontal and pulpal healing after replantation was examined in 30 green vervet monkeys (cercopithecus aethiops) in which a total of 50 teeth were replanted. Maxillary central incisors with different stages of root development (immature, young mature and mature root formation) were replanted with untreated pulps or after root canal treatment with gutta percha and Kerr® sealer. The extra-alveolar period in all groups was 18 min. The animals were sacrificed 8 weeks after replantation and the teeth examined histologically. The following histologic parameters were registered for each tooth: surface resorption, inflammatory resorption, replacement resorption (ankylosis), downgrowth of pocket epithelium, periapical inflammatory changes and extent of vital pulp. Histologic analysis showed that the extent of vital pulp was significantly related to the stage of root development, being almost complete in teeth with immature roots and almost totally lacking in young mature and mature teeth. Surface resorption was found with the same frequency in the different root development groups while inflammatory resorption was slightly more frequent in young mature teeth than in mature teeth, a finding possibly related to a protective action of a thick cementum layer in the mature teeth. Replacement resorption was found with almost the same frequency in the different root development groups in non-endodontically treated teeth. As ankylosis is the most important factor determining the prognosis of replanted and autotrans-planted teeth, the present findings indicate that replantation and auto-transplantation of mature teeth could be of clinical use.

Evaluation of the accuracy of the neosono-D electronic apex locator

The efficacy of an electronic device to locate the apical foramen was evaluated in vivo in 24 mature and 5 immature root canals in human teeth. The results were obtained by direct microscopic and radiographic measurements. The device was found to be consistently accurate in mature teeth but inaccurate in immature teeth.

Two NAD-dependent alcohol dehydrogenases (E.C. 1.1.1.1) in callus cultures of wheat, rye and triticale

Two NAD-dependent alcohol dehydrogenases ADH-1 and ADH-2, under independent genetic control of genes designated as Adh-1 and Adh-2 located on chromosomes 4A, 4B and 4D, have been reported in aestivum wheat (Hart 1980). Only ADH-1 is expressed in developing seeds, dry seeds, pollen and germinating seedlings. ADH-2 can be induced in seedling roots or shoots under conditions of partial anaerobiosis or by certain chemicals. Expression of ADH-1 and ADH-2 isoenzymes was investigated in undifferentiated calli from aestivum and durum wheats, rye, triticale and also in in vitro regenerated roots and leaves from aestivum cultures. Wheat callus cultures originating from seed, mature and immature embryos, mesocotyl and root, as well as cultures grown on media containing different supplements did not show any variation in the overall expression of ADH-1 or ADH-2, although differences in the band intensities were observed. The callus isoenzyme pattern was similar to that observed in roots under anaerobic conditions. Both ADH-1 and ADH-2 were expressed in in vitro regenerated roots but were absent in regenerated leaves. Expression of ADH-1 and ADH-2 in wheat calli seems to be related to the type of differentiation.

A biochemical study of alkaline phosphatase isolated from rabbit incisor dentine

A matrix protein with alkaline phosphatase (APase) activity was isolated by aqueous butanol extraction. Purification of the enzyme resulted in a preparation showing properties of a nonspecific APase similar to the enzyme isolated from odontoblasts by other workers. The natural substrate of the enzyme is unclear and highest activity was observed with the substrate p-nitrophenyl phosphate. The enzyme activity was maximal at the immature root apex of the incisor with little activity elsewhere along the tooth.

Sucrose Translocation and Storage in the Sugar Beet

Several physiological processes were studied during sugar beet root development to determine the cellular events that are temporally correlated with sucrose storage. The prestorage stage was characterized by a marked increase in root fresh weight and a low sucrose to glucose ratio. Carbon derived from (14)C-sucrose accumulation was partitioned into protein and structural carbohydrate fractions and their amino acid, organic acid, and hexose precursors. The immature root contained high soluble acid invertase activity (V(max) 20 micromoles per hour per milligram protein; K(m) 2 to 3 millimolar) which disappeared prior to sucrose storage. Sucrose storage was characterized by carbon derived from (14)C-sucrose uptake being partitioned into the sucrose fraction with little evidence of further metabolism. The onset of storage was accompanied by the appearance of sucrose synthetase activity (V(max) 12 micromoles per hour per milligram protein; K(m) 7 millimolar). Neither sucrose phosphate synthetase nor alkaline invertase activities were detected during beet development. Intact sugar beet plants (containing a 100-gram beet) exported 70% of the translocate to the beet, greater than 90% of which was retained as sucrose with little subsequent conversions.

Changes in Carbohydrate Levels in Red Kidney Bean (Phaseolus vulgarisL.) Exposed to Sulphur Dioxide

Red kidney bean (Phaseolus vulgaris L.) was exposed to various concentrations of S02 for 24 h (16 h light/8 h dark photoperiod) with continuous monitoring of photosynthetic and respiratory activity. Plants were harvested at the end of the dark period into samples of mature and immature leaf tissue, stems, and roots for determination of sugar and starch levels. In all tissue samples the levels of total sugars were increased by exposure to the lower concentrations of S02, but decreased by the higher concentrations. Starch levels in leaves followed a similar trend. Increases in sugar and starch levels preceded symptoms of visible injury. Decreasing rates of photosynthesis were correlated with increasing rates of respiration, the occurrence of visible injury, and the depletion of sugar and starch levels.

A clinical report on partial pulpotomy and capping with calcium hydroxide in permanent incisors with complicated crown fracture

The exposed pulps of 60 permanent incisors with a complicated crown fracture were treated with partial pulpotomy and calcium hydroxide dressing. The interval between accident and treatment varied from one to 2,160 hours and the size of the pulpal exposure varied from 0.5 to 4.0 mm. Of the teeth, 28 had immature and 32 had mature roots. The treatment was successful in 58 teeth or 96% according to the following criteria: no clinical symptoms, no radiographically observed intraradicular or periradicular pathologic changes, continued development of an immature root, radiographically observed and clinically verified hard tissue barrier, and sensitivity to electrical stimulation. The follow-up examination varied from 14 to 60 months, with an average of 31 months. The exposed pulps of 60 permanent incisors with a complicated crown fracture were treated with partial pulpotomy and calcium hydroxide dressing. The interval between accident and treatment varied from one to 2,160 hours and the size of the pulpal exposure varied from 0.5 to 4.0 mm. Of the teeth, 28 had immature and 32 had mature roots. The treatment was successful in 58 teeth or 96% according to the following criteria: no clinical symptoms, no radiographically observed intraradicular or periradicular pathologic changes, continued development of an immature root, radiographically observed and clinically verified hard tissue barrier, and sensitivity to electrical stimulation. The follow-up examination varied from 14 to 60 months, with an average of 31 months.

Noninduced apical closure in immature roots of dogs' teeth

The pulps in 40 permanent premolars with immature apices were extirpated in seven young dogs. The root canals in 20 teeth were left open to the oral environment and the access openings of the other 20 teeth were closed with Cavit. No drug was used in the canals to stimulate or to induce apexification. After 7 to 11 weeks, radiographic and histologic examination showed that complete apical closure had occurred in 85.5% of the canals that were left open and in 50% of those that were closed. It was concluded that drugs such as calcium hydroxide were not necessary to stimulate apical closure in dogs.