SEARCH · PubMed Health

Results for “root development”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 199 records · Page 11Linked to original sources

PubMed2004

Manipulation of root hair development and sorgoleone production in sorghum seedlings.

Sorghum (Sorghum bicolor) roots exude a potent bioherbicide sorgoleone. Previous work indicates that sorgoleone is produced in living root hairs. We have developed a mist system that resulted in abundant production of root hairs exuding sorgoleone and a mat system that significantly inhibited root hair development and consequently sorgoleone production. Applying Ag+ (an ethylene action inhibitor) at 1.2 mM to the seedlings grown in the mist system also inhibited root hair formation and elongation. Hypoxic conditions in the mist system did not result in the inhibition of root hair growth as compared to the standard air atmosphere (20.8% O2). Applying ethephon (an ethylene-releasing agent) at 0.031 mM to the roots of seedlings grown in the mat system with water running at 1 ml/min reversed the inhibition of root hair development by water movement. These results indicate that either water movement or ethylene can be utilized to manipulate root hair development and sorgoleone production in sorghum seedlings. It is hypothesized that water movement reduced the local ethylene concentration on the root surface and consequently inhibited root hair development of sorghum seedlings grown in the mat system.

Benzoquinones↗

PubMed2000

Through form to function: root hair development and nutrient uptake.

Root hairs project from the surface of the root to aid nutrient and water uptake and to anchor the plant in the soil. Their formation involves the precise control of cell fate and localized cell growth. We are now beginning to unravel the complexities of the molecular interactions that underlie this developmental regulation. In addition, after years of speculation, nutrient transport by root hairs has been demonstrated clearly at the physiological and molecular level, with evidence for root hairs being intense sites of H(+)-ATPase activity and involved in the uptake of Ca(2+), K(+), NH(4)(+), NO(3)(-), Mn(2+), Zn(2+), Cl(-) and H(2)PO(4)(-).

Nitrogen↗

PubMed1996

Control of root growth and development by cyclin expression.

Root development is plastic, with post-embryonic organogenesis being mediated by meristems. Although cell division is intrinsic to meristem initiation, maintenance and proliferative growth, the role of the cell cycle in regulating growth and development is unclear. To address this question, we examined the expression of cdc2 and cye genes, which encode the catalytic and regulatory subunits, respectively, of cyclin-dependent protein kinases that control progression through the cell cycle. Unlike cdc2, which is expressed not only in apical meristems but also before lateral root initiation in quiescent, pericycle cells arrested in the G2 phase of the cell cycle, cyc1At transcripts accumulate specifically in dividing cells immediately before cytokinesis. Ectopic expression of cyc1At under the control of the cdc2aAt promoter in Arabidopsis plants markedly accelerates growth without altering the pattern of lateral root development or inducing neoplasia. Thus cyclin expression is a limiting factor for growth, which in turn drives indeterminate development of the root system.

Arabidopsis↗

PubMed1984

Dorsal root ganglia development in chicks following partial ablation of the neural crest.

To assess the effects of reduced competition for peripheral targets on developing brachial dorsal root ganglia (DRG), chick embryos were subjected to partial ablations of the brachial neural crest at stages 13 or 14 (Hamburger, V., and H.L. Hamilton (1951) J. Morphol. 88: 49-92), using an ophthalmological cauterization unit. In the initial studies reported here, ganglia developing from the remaining crest material were examined for ganglionic volume and neuronal size, neuronal number, and degenerative activity at stage 35. Results showed that the lesion procedure resulted in the reduction or absence of one or two ganglia on each side at the level of DRG 15 to DRG 17. Hypertrophies occurred in other ganglia remaining at these and at more rostral levels and ranged up to 220%. These hypertrophies were most pronounced, however, not in the ganglia adjacent to those lesioned but rather in more remote ganglia, including those at cervical levels. Accompanying these ganglionic changes were significant alterations in all three neuronal parameters examined. The findings clearly demonstrate a responsiveness of chick brachial DRG to reduced competition resulting from neural crest ablations and that such responsiveness occurs along several axial segments.

Animals↗

PubMedDate not supplied

Histopathological evaluation of subcutaneous tissue reaction in mice to a calcium hydroxide paste developed for root canal fillings.

We aimed to evaluate the subcutaneous tissue reaction to a new calcium hydroxide paste for root canal fillings developed by Neo Dental Chemical Products Co., Tokyo, Japan. We injected calcium hydroxide paste and a water-based control subcutaneously into the dorsal area of 6-week-old anaesthetized male ddY mice. The tissue surrounding the injection sites was removed from mice in each group, 2 days, 1 week, 3 weeks and 12 weeks after the injection, and histopathologically examined. We found necrotic and degenerative changes, as well as foreign body reaction or proliferation of granulation tissue in specimens from both groups until 3 weeks after the injection. Some lymphocyte infiltration was observed in the 12-week specimens of the control group only. We conclude that calcium hydroxide paste is safe to use as a root canal filling material.

Animals↗

PubMed1994

Getting to the root of plant development: the genetics of Arabidopsis root formation.

Root development in Arabidopsis thaliana is amenable to molecular genetic analyses because of its simplicity and accessibility. Genetic screens have identified a rich collection of mutants that can be used to address a variety of fundamental questions in plant developmental biology. These mutants have defects in genes that govern organ formation, meristem activity, cell differentiation and response to environmental conditions.

Arabidopsis↗

PubMed2000

Genetic regulation of root hair development in Arabidopsis thaliana: a network model.

The root epidermis of Arabidopsis thaliana is formed by alternate files of hair and non-hair cells. Epidermal cells overlying two cortex cells eventually develop a hair, while those overlying only one cortex cell do not. Here we propose a network model that integrates most of the available genetic and molecular data on the regulatory and signaling pathways underlying root epidermal differentiation. The network architecture includes two pathways; one formed by the genes TTG, R homolog, GL2 and CPC, and the other one by the signal transduction proteins ETR1 and CTR1. Both parallel pathways regulate the activity of AXR2 and RHD6, which in turn control the development of root hairs. The regulatory network was simulated as a dynamical system of eight discrete state variables. The distinction between epidermal cells contacting one or two cortical cells was accounted for by fixing the initial states of CPC and ETR1 proteins. The model allows for predictions of mutants and pharmacological effects because it includes the ethylene receptor. The dynamical system reaches one of the six stable states depending upon the initial state of the CPC variable and the ethylene receptor. Two of the stable states describe the activation patterns observed in mature trichoblasts (hair cells) and atrichoblasts (non-hair cells) in the wild-type phenotype and under normal ethylene availability. The other four states correspond to changes in the number of hair cells due to experimentally induced changes in ethylene availability. This model provides a hypothesis on the interactions among genes that encode transcription factors that regulate root hair development and the proteins involved in the ethylene transduction pathway. This is the first effort to use a dynamical system to understand the complex genetic regulatory interactions that rule Arabidopsis primary root development. The advantages of this type of models over static schematic representations are discussed.

Arabidopsis↗

PubMed2000

Pulp revascularization of replanted immature dog teeth after different treatment methods.

The purpose of the present study was to determine the effect of topical treatment with doxycycline and/or the application of unfilled resin to the anatomical crown on the occurrence of revascularization in reimplanted dog teeth. Ninety-six teeth in 4 young mongrel dogs were used. Eighty one teeth were atraumatically extracted and divided into four groups. Group 1, 17 teeth were kept dry for 5 min and then replanted. Group 2, 21 teeth were soaked with a freshly prepared solution of doxycycline (1 mg/20 mL saline) for 5 min before replantation. Group 3, 23 teeth were soaked with the doxycycline solution for 5 min, and then replanted. The crowns were coated with 2 layers of light cured unfilled resin. Group 4, 20 teeth were kept dry for 5 min, and then replanted. The crowns were treated as with the teeth in Group 3. Three months after surgery, radiographic evaluation revealed that 27 teeth had continued root development and 32 teeth showed arrested root development with periradicular pathosis. The remaining 17 teeth, which had arrested root development but no signs of periradicular pathosis, were all histologically evaluated for final assessment. The occurrence of revascularization according to treatment group was 29.4%, 60%, 60%, 36.8% in Group 1, 2, 3, and 4, respectively. A multiple logistic regression analysis in SAS indicated there was no significant association between vitality and dog (P = 0.7564). Soaking for 5 min in doxycycline significantly increased the revascularization rate (P = 0.024) while the addition of resin to the crown did not result in an increased incidence of pulp revascularization (P = 0.823).

Administration, Topical↗

PubMed1996

The Arabidopsis Athb-10 (GLABRA2) is an HD-Zip protein required for regulation of root hair development.

Homeodomain-leucine zipper (HD-Zip) proteins are putative transcription factors identified only in plants. Related Arabidopsis homeobox genes, isolated by virtue of sequence conservation within the helix-3 region of the homeodomain, fall into four families based on sequence similarity. This paper reports the characterization of Athb-10, a 747 amino acid protein belonging to the fourth HD-ZIP family. The studies indicate that, although less conserved, the leucine zipper of Athb-10 can functionally replace that of Athb-2 in an in vitro DNA-binding assay. Gene mapping experiments and sequence comparison analysis revealed that Athb-10 corresponds to GLABRA2, a homeodomain protein involved in trichome development. The mRNA expression analysis revealed that Athb-10/GLABRA2 is expressed not only in trichome-bearing organs, but also in the root. The analysis of wild-type and mutant plants showed that the Athb-10/GLABRA2 gene expression in the aerial part of the plant and in the root is affected by mutations at the TTG locus. Morphological analysis of the g/2-1 mutant revealed that the gene is necessary not only for local outgrowth of the trichome, but also for the regulation of root hair development in a subset of epidermal cells. Interestingly, the development of root hair cells in a position normally occupied by non-hair cells is dependent upon the ethylene regime in which the gl2-1 plants are grown. Sequence analysis of the gl2-1 allele revealed that the mutant gene encodes a truncated protein that might still retain a partial activity responsible for the formation of aborted trichomes and for the ethylene-dependent regulation of root hair formation.

Amino Acid Sequence↗

PubMed1989

Consequences of somite manipulation on the pattern of dorsal root ganglion development.

We have investigated dorsal root ganglion formation, in the avian embryo, as a function of the composition of the paraxial somitic mesoderm. Three or four contiguous young somites were unilaterally removed from chick embryos and replaced by multiple cranial or caudal half-somites from quail embryos. Migration of neural crest cells and formation of DRG were subsequently visualized both by the HNK-1 antibody and the Feulgen nuclear stain. At advanced migratory stages (as defined by Teillet et al. Devl Biol. 120, 329-347 1987), neural crest cells apposed to the dorsolateral faces of the neural tube were distributed in a continuous, nonsegmented pattern that was indistinguishable on unoperated sides and on sides into which either half of the somites had been grafted. In contrast, ventrolaterally, neural crest cells were distributed segmentally close to the neural tube and within the cranial part of each normal sclerotome, whereas they displayed a nonsegmental distribution when the graft involved multiple cranial half-somites or were virtually absent when multiple caudal half-somites had been implanted. In spite of the identical dorsal distribution of neural crest cells in all embryos, profound differences in the size and segmentation of DRG were observed during gangliogenesis (E4-9) according to the type of graft that had been performed. Thus when the implant consisted of compound cranial half-somites, giant, coalesced ganglia developed, encompassing the entire length of the graft. On the other hand, very small, dorsally located ganglia with irregular segmentation were seen at the level corresponding to the graft of multiple caudal half-somites. We conclude that normal morphogenesis of dorsal root ganglia depends upon the craniocaudal integrity of the somites.

Animals↗

PubMed2002

Role of Pseudomonas putida indoleacetic acid in development of the host plant root system.

Many plant-associated bacteria synthesize the phytohormone indoleacetic acid (IAA). While IAA produced by phytopathogenic bacteria, mainly by the indoleacetamide pathway, has been implicated in the induction of plant tumors, it is not clear whether IAA synthesized by beneficial bacteria, usually via the indolepyruvic acid pathway, is involved in plant growth promotion. To determine whether bacterial IAA enhances root development in host plants, the ipdc gene that encodes indolepyruvate decarboxylase, a key enzyme in the indolepyruvic acid pathway, was isolated from the plant growth-promoting bacterium Pseudomonas putida GR12-2 and an IAA-deficient mutant constructed by insertional mutagenesis. The canola seedling primary roots from seeds treated with wild-type P. putida GR12-2 were on average 35 to 50% longer than the roots from seeds treated with the IAA-deficient mutant and the roots from uninoculated seeds. In addition, exposing mung bean cuttings to high levels of IAA by soaking them in a suspension of the wild-type strain stimulated the formation of many, very small, adventitious roots. Formation of fewer roots was stimulated by treatment with the IAA-deficient mutant. These results suggest that bacterial IAA plays a major role in the development of the host plant root system.

Amino Acid Sequence↗

PubMed1995

Plant development: pulled up by the roots.

Recent advances in the study of root development in Arabidopsis have begun to yield mechanistic insights into the processes that underpin morphogenesis, pattern formation and cell differentiation in plants. The most exciting feature of these advances is that, as a consequence of the simple and largely invariant cellular architecture of the root, the processes can be studied at a cellular level. Nevertheless, it is clear that although the cell lineages of the root are relatively invariant, we have no evidence that lineage per se is an important regulator of development. Instead, all the evidence indicates that the positional regulation of inductive cues is of primary importance. The availability of new root mutants is alerting us to the complexity of the contribution of cell size and cell expansion to plant development.

Arabidopsis↗

PubMedDate not supplied

[Autotransplantation of human tooth germs].

The Author presents three cases of tooth germ transplantation which were periodically checked by x-rays to show the progressive root development. The clinical result obtained were quite satisfactory. The situations requiring the transplantations in the 3 cases were all rather unusual: in one case the tooth germ was inside a large follicular cyst; in the other two the tooth germs were mesiodistally rotated 90 degrees which made eruption impossible. The cases described differ from cases frequently found in literature in that the transplanted tooth germs were in the initial stage of development; the roots, in fact, had not yet begun to develop. All the tooth germs transplanted, once their growth was completed, presented two types of morphological alternations. A reduction in the volume of the pulpar chamber and a pad of radiopaque tissue around the neck of the tooth. We have attempted to give an explanation for both of these alterations. The cases as well as the surgical procedures are described in detail.

Child↗

PubMed2003

Relationships among shoot sinks for resources exported from nodal roots regulate branch development of distal non-rooted portions of Trifolium repens L.

Two manipulative experiments tested hypotheses pertaining to the correlative control exerted by nodal roots on branch development of the distal non-rooted portion of Trifolium repens growing clonally under near-optimal conditions. The two experiments, differing in their pattern of excision to manipulate the number of branches formed at the first 9-10 phytomers distal to the youngest nodal root, each found that after 20 phytomers of growth the total number of lateral branches formed on the primary stolon remained between five and seven regardless of where the branches formed along the stolon. Additional treatments established that nodal roots influenced branch development via relationships among shoot sinks for the root-supplied resources rather than through variation in the supply of such resources induced by fluctuations in photosynthate supply to roots from branches. Regression analysis of data pooled from treatments of both experiments confirmed that shoot-sink relationships for root- supplied resources controlled the branching processes on the non-rooted portion of plants. A disbudding treatment, which removed all the apical and axillary buds present on basal branches, but left other branch tissues intact, increased branch development of the apical region in the same way as did complete excision of the basal lateral branches. The apical buds and the elongation processes occurring immediately proximal to the buds were thus identified as strong sinks for the root-supplied resources. Such results suggest that branch development on the non-rooted shoot portion distal to the youngest nodal root is regulated by competition among sinks for root-derived resources, of limited availability, necessary for the processes of elongation of axillary buds and the primary stolon apical bud.

Homeostasis↗

PubMed1997

Al Inhibits Both Shoot Development and Root Growth in als3, an Al-Sensitive Arabidopsis Mutant.

In als3, an Al-sensitive Arabidopsis mutant, shoot development and root growth are sensitive to Al. Mutant als3 seedlings grown in an Al-containing medium exhibit severely inhibited leaf expansion and root growth. In the presence of Al, unexpanded leaves accumulate callose, an indicator of Al damage in roots. The possibility that the inhibition of shoot development in als3 is due to the hyperaccumulation of Al in this tissue was examined. However, it was found that the levels of Al that accumulated in shoots of als3 are not different from the wild type. The inhibition of shoot development in als3 is not a consequence of nonspecific damage to roots, because other metals (e.g. LaCl3 or CuSO4) that strongly inhibit root growth did not block shoot development in als3 seedlings. Al did not block leaf development in excised als3 shoots grown in an Al-containing medium, demonstrating that the Al-induced damage in als3 shoots was dependent on the presence of roots. This suggests that Al inhibition of als3 shoot development may be a delocalized response to Al-induced stresses in roots following Al exposure.

Journal Article↗

PubMed2002

Changes in root length during orthodontic treatment: advantages for immature teeth.

The purpose of the study was to investigate root lengthening during orthodontic treatment in relation to the age of the patient, the developmental stage of the root, and the anticipated growth. Specifically, the potential benefit of treating young teeth was addressed. The sample consisted of 80 patients with Angle Class II division 1 malocclusions, treated with extraction of at least two maxillary first premolars, and edgewise technique with 0.018-inch slot brackets. Additionally, a cross-sectional control group of 66 untreated individuals matched to gender, and pre- and post-treatment age of the experimental group was included. Crown and root lengths of the maxillary incisors were measured on peri-apical radiographs before and after treatment, and corrected for image distortion. The stage of root development before treatment was recorded. Root elongation during treatment was found for 50 out of the 280 examined teeth. Age at treatment start was significantly higher among the patients showing root shortening of the lateral incisors during treatment than among those showing root elongation (P < 0.05). The stage of root development was significantly related to the direction of root length change, i.e. shortening or elongation. Roots elongated during treatment did not differ in length from untreated teeth of similarly aged individuals. There was no significant difference in the extent of root lengthening between the roots elongated during treatment and the normal root lengthening in age-matched untreated individuals. Post-treatment root length was significantly related to pre-treatment age. Roots that were incompletely developed before treatment reached a significantly greater length than those that were fully developed at the start of treatment. The results of this study show a definite advantage for younger teeth with regard to post-treatment root length. This finding may influence treatment planning strategy.

Age Factors↗

PubMed2001

Transcriptional responses in the hemiparasitic plant Triphysaria versicolor to host plant signals.

Parasitic plants in the Scrophulariaceae use chemicals released by host plant roots to signal developmental processes critical for heterotrophy. Haustoria, parasitic plant structures that attach to and invade host roots, develop on roots of the hemiparasitic plant Triphysaria versicolor within a few hours of exposure to either maize (Zea mays) root exudate or purified haustoria-inducing factors. We prepared a normalized, subtractive cDNA library enriched for transcripts differentially abundant in T. versicolor root tips treated with the allelopathic quinone 2,6-dimethoxybenzoquinone (DMBQ). Northern analyses estimated that about 10% of the cDNAs represent transcripts strongly up-regulated in roots exposed to DMBQ. Northern and reverse northern analyses demonstrated that most DMBQ-responsive messages were similarly up-regulated in T. versicolor roots exposed to maize root exudates. From the cDNA sequences we assembled a unigene set of 137 distinct transcripts and assigned functions by homology comparisons. Many of the proteins encoded by the transcripts are predicted to function in quinone detoxification, whereas others are more likely associated with haustorium development. The identification of genes transcriptionally regulated by haustorium-inducing factors provides a framework for dissecting genetic pathways recruited by parasitic plants during the transition to heterotrophic growth.

Benzoquinones↗

PubMed1999

Interactive effects of selenium and mercury on the restoration potential of leaves of the medicinal plant, Portulaca oleracea Linn.

Leaves of Portulaca oleracea have the potential of regeneration, when grown in a distilled water medium. The two heavy metals, Se and Hg individually and in combination affected both shoot and root development. They completely arrested shoot development at all concentrations. However, they produced concentration-dependent changes in the development of roots, which ranged from their complete inhibition to variation in their initiation time, number and length. Leaf decay was initiated on day 46 in control leaves. Concentration-dependent changes were also observed in the time of initiation and magnitude of decay of leaves. The data indicates that Hg was more toxic than Se. The protective effect of Se against Hg toxicity was evident only at very low concentrations. With further increases in the concentration of both Se and Hg, the protective effect decreased and simultaneously the toxicity increased. Following the decay of leaves, a pink colour development was observed only on leaves exposed to Se. Microbial analysis of leaves showed the presence of Acinetobacter only in Se-exposed leaves. Acinetobacter was therefore considered as probably involved in the formation of elemental Se, which produced a pink colour.

Acinetobacter↗