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 559 records · Page 31Linked to original sources

PubMed2002

Two new loci, PLEIADE and HYADE, implicate organ-specific regulation of cytokinesis in Arabidopsis.

In screens for regulators of root morphogenesis in Arabidopsis we isolated six new recessive mutants with irregular cell expansion. Complementation analyses placed the mutations in two loci, PLEIADE (PLE) and HYADE (HYA). Phenotypic analyses revealed multinucleated cells, cell wall stubs, and synchronized cell divisions in incompletely separated cells that are all characteristics of defective cytokinesis. These defects were pronounced in roots and undetectable in aerial organs. In addition, fertility and germination were not affected by the mutations. Thus, the alleles that we have isolated of PLE and HYA suggest that the genes may encode organ-specific components needed primarily during root development. Analysis of microtubule arrays during cell cycle in ple and hya roots indicates that the presence of several synchronized nuclei influences the position of preprophase band, mitotic spindles, and phragmoplasts. The enhanced and synergistic phenotype of PLE/ple.hya/hya seedlings and double mutants point to a role of PLE and HYA in the same process. These mutants provide tools to elucidate the regulation of nuclear cytoskeletal interactions during cell division and cytokinesis.

Arabidopsis↗

PubMed1996

The Effect of Nitrogen Nutrition on the Cellular Localization of Glutamine Synthetase Isoforms in Barley Roots.

Glutamine synthetase (GS) was detected by immunogold localization in the cytosol and plastids of roots of 7-d-old barley (Hordeum vulgare L. cv Klaxon) seedlings grown in the presence or absence of NO3- (15 mM) or NH4+ (30 mM). The number of GS polypeptides changed during root development, and this was affected by N nutrition. There was no evidence of a NO3--inducible root plastid GS.In apical 5- to 10-mm regions of the root the concentration of immunogold labeling of cytosolic GS was higher in the cortical parenchyma than in the vascular cells of the stele, irrespective of N nutrition. This labeling was at least 50% higher in both cell types in N-free compared with N-grown (either NO3- or NH4+) seedlings. In contrast, GS specific activity was highest in roots of NO3--grown seedlings. It is suggested that this indicates the presence of inactive GS in roots grown without N. This study has identified both cell- and development-specific responses of GS to N nutrition.

Journal Article↗

PubMed2000

Stimulation of border cell production in response to increased carbon dioxide levels.

Field soil atmospheres have higher CO(2) and lower O(2) concentrations compared with ambient atmosphere, but little is known about the impact of such conditions on root exudation patterns. We used altered levels of CO(2) and O(2) relative to ambient conditions to examine the influence of the atmosphere on the production of root border cells by pea (Pisum sativum) root tips. During germination, atmospheres with high CO(2) and low O(2) inhibited root development and border cell separation in pea seedlings. Later in development, the same atmospheric composition stimulated border cell separation without significantly influencing root growth. Increased CO(2), not low O(2), was responsible for the observed stimulation of border cell number. High CO(2) apparently can override endogenous signals that regulate the number of border cells released from pea roots into the rhizosphere. The same conditions that stimulated border cell production in pea had no such effect in alfalfa (Medicago sativa).

Carbon Dioxide↗

PubMed2005

The influence of external nitrogen on carbon allocation to Glomus intraradices in monoxenic arbuscular mycorrhiza.

The influence of external nitrogen (N) on carbon (C) allocation and processes related to phosphorus (P) metabolism were studied in monoxenic arbuscular mycorrhiza (AM) cultures of Daucus carota. Fungal hyphae of Glomus intraradices proliferated from colonized roots growing on solid medium into C-free liquid minimal medium with two different N and P levels. Furthermore, we exposed the colonized roots to high or low N availability and then studied the mycelial development. Roots were provided with (13)C-glucose in order to follow the C allocation. The mycelium was analysed for phosphatase activity and transcription levels of two nutrient regulated genes. High N availability to the monoxenic AM root reduced the C allocation to the AM fungus while N availability to the mycelium was important for the upregulation of the fungal inorganic phosphorus (Pi)-transporter GiPT. We found that N availability can regulate nutritional processes in arbuscular mycorrhiza. We conclude that negative impacts of N on AM abundance are caused by reduced C allocation from the plant. Upregulation of the fungal Pi-transporter GiPT indicated that increased N availability might induce P limitation in the mycelium.

Base Sequence↗

PubMed1997

A histological and quantitative histomorphometric study of apexification of nonvital permanent incisors of vervet monkeys after repeated root filling with a calcium hydroxide paste.

The purpose of this study was to compare the effect of a monthly refilling of the root canals with calcium hydroxide paste with a single packing or replacement of the paste at 3 months on the apexification of nonvital maxillary incisors of vervet monkeys. Forty-eight maxillary incisors from 12 monkeys were used following radiographic determination that root development was incomplete. The pulps were extirpated under general anesthesia and the root canals filed and cleaned. The root canals were filled with a commercial calcium hydroxide paste, Calxyl, and a temporary cavity filling placed. Twelve teeth were left without further treatment. The calcium hydroxide paste was replaced in 12 teeth after a 3-month interval, and in the remaining 24 teeth the calcium hydroxide root filling was replaced five times at monthly intervals. The monkeys were killed after 6 months, and blocks of the teeth and surrounding tissues were embedded, decalcified and 6 microns serial sections prepared and stained. The sections were studied histologically to evaluate 11 parameters. Significant differences were found in the amount of calcium hydroxide at the apices, the presence of new cementum on the roots and the degree of inflammation, all of which were better in the monthly refill group. Histomorphometric measurements to evaluate the obturation of the open apices and the volume of new primary osteocementum showed no significant difference between the three groups. It was suggested that after the initial root filling with calcium hydroxide there was nothing to be gained by repeated root filling either monthly or after 3 months, for at least 6 months.

Analysis of Variance↗

PubMed2006

Alfalfa (Medicago sativa L.).

A protocol for rapid, highly efficient transformation of alfalfa is described. Leaf explants from growth chamber-grown plants of a highly regenerable genotype are surface-sterilized, the margins are removed, and explants are inoculated with Agrobacterium tumefaciens strain LBA4404 carrying the T-DNA vector of interest. The explants and bacteria are cocultured for 7 to 8 d. Bacteria are removed by rinsing explants in sterile distilled water and by culture on regeneration medium containing the antibiotics carbenicillin or ticarcillin. Transformed callus is selected using kanamycin. Somatic embryos are induced by culture of callus on medium lacking plant growth regulators. As mature cotyledonary stage embryos arise, they are transferred to a fresh medium for shoot development and finally to a medium lacking kanamycin for continued shoot and root development. Transgenic plants can be produced in 9 wk with this protocol. Typically 60 to 80% of inoculated explants produce transgenic plants, and escapes are rare.

Agrobacterium tumefaciens↗

PubMed1998

Cortical tissue-specific accumulation of the root-specific ns-LTP transcripts in the bean (Phaseolus vulgaris) seedlings.

The characterization of a cDNA clone encoding non-specific lipid transfer protein (PvLTP, formerly named PVR3) in the roots of bean seedlings has been previously reported. In this study, we examined the temporal and spatial accumulation of PvLTP mRNA and the effect of the auxin naphthaleneacetic acid (NAA) on the accumulation of PvLTP mRNA during root development. In situ hybridization showed that accumulation of PvLTP mRNA is highly tissue-specific. Accumulation was detected in the cortical tissue, but not in other tissues of root, including the quiescent center and root cap. Within the cortical tissue, accumulation of PvLTP mRNA was developmentally regulated; accumulation of PvLTP mRNA was high in the cortical tissue of the proximal and ground meristem and declined as cortical tissue developed further. Since the appropriate distribution of auxin is an important factor responsible for the maintenance of root meristem organization. We examined effect of auxin on the accumulation of PvLTP mRNA in relation to the development of cortical tissue. In bean seedlings grown on medium supplemented with 5 microM NAA, morphological alternations, including radial root expansion and abnormal tissue organization in the root apical meristem, were observed. Only faint accumulation signals of PvLTP mRNA were observed in the cortical tissue of proximal meristem region, indicating that cortical tissue development was repressed by exogenous NAA. However, our results suggest that the change in accumulation of PvLTP mRNA is not direct regulatory effect but reflective effect of altered development of cortical tissue that was induced by exogenous NAA. The temporal and spatial accumulation of PvLTP mRNA indicates that PvLTP is a useful marker for the development of cortical tissue in the root tip in bean seedlings.

Carrier Proteins↗

PubMed1995

The effect of various fluoride compounds on the development of experimental root surface caries in hamsters.

The aim of this investigation was to evaluate the effect of topical applications of various fluoride compounds on the development of root surface caries in hamsters. Male golden hamsters (n = 115) were divided into 7 groups and were given a caries-promoting diet. Six groups were infected with Actinomyces viscosus ATCC 15987; and to 5 infected groups, distilled water (DW) and solutions containing 500 ppmF of acidulated-phosphate fluoride (APF), stannous fluoride (SnF2), copper fluoride (CuF2), and titanium tetrafluoride (TiF4) were applied topically to the first mandibular molars once daily, 7 days a week, over a 24-week period. A grid method was used to asses the periodontal changes and root surface caries on the first molars. Plaque accumulation was reduced most by SnF2; and alveolar bone loss was more reduced by SnF2 and CuF2. Root surface caries was significantly prevented in all fluoride groups when compared to an infected control group; and TiF4 was the most effective fluoride compound followed by SnF2, CuF2, and APF. Root caries scores of the TiF4 and SnF2 groups were significantly lower than those of the DW group. It was concluded that all fluoride tested may prevent the development of root surface caries in hamsters.

Acidulated Phosphate Fluoride↗

PubMed1985

Dental development in precocious puberty.

One hundred and one children with precocious puberty were given an oral examination. Dental root development was assessed using panoramic radiographs. All mandibular canines, pre-molars, and molars which could be visualized without apparent distortion were included. The patients were grouped for analysis according to the etiology of their precocity, e.g., McCune-Albright syndrome, familial male, congenital adrenal hyperplasia, central nervous system lesions, and idiopathic precocious puberty. Dental development was significantly retarded relative to their chronological age in patients with idiopathic precocious puberty. However, no significant abnormal dental development was detected in any of the other groups. Individual oral-facial growth and development remain the primary considerations for timing orthodontic treatment.

Age Determination by Skeleton↗

PubMed2002

Humic acids isolated from earthworm compost enhance root elongation, lateral root emergence, and plasma membrane H+-ATPase activity in maize roots.

Earthworms (Eisenia foetida) produce humic substances that can influence plant growth by mechanisms that are not yet clear. In this work, we investigated the effects of humic acids (HAs) isolated from cattle manure earthworm compost on the earliest stages of lateral root development and on the plasma membrane H(+)-ATPase activity. These HAs enhance the root growth of maize (Zea mays) seedlings in conjunction with a marked proliferation of sites of lateral root emergence. They also stimulate the plasma membrane H(+)-ATPase activity, apparently associated with an ability to promote expression of this enzyme. In addition, structural analysis reveals the presence of exchangeable auxin groups in the macrostructure of the earthworm compost HA. These results may shed light on the hormonal activity that has been postulated for these humic substances.

Animals↗

PubMed1994

Phosphorus Stress-Induced Proteoid Roots Show Altered Metabolism in Lupinus albus.

Proteoid roots develop in Lupinus albus L. in response to nutrient stress, especially P. Proteoid roots excrete citrate and thus increase the availability of P, Fe, and Mn in the rhizosphere. In an effort to understand citrate synthesis and organic acid metabolism in proteoid roots of lupin, we have evaluated in vitro enzyme activities of citrate synthase (CS), malate dehydrogenase (MDH), and phosphoenolpyruvate carboxylase (PEPC) in proteoid and normal roots of plants grown with or without P. Organic acid concentrations, respiration rates, and dark 14CO2-labeling patterns were also determined. The in vitro specific activities of CS, MDH, and PEPC and in vivo dark 14CO2 fixation were higher in proteoid roots compared to normal roots, particularly under P stress. Western blot analysis showed that PEPC enzyme protein was more highly expressed in -P proteoid roots compared to other tissues. The majority of the fixed 14C was found in organic acids, predominantly malate and citrate. A larger fraction of citrate was labeled in P- stressed proteoid roots compared to other root tissue. Respiration rates of proteoid roots were 31% less than those of normal roots. The data provide evidence for increased synthesis of citrate in proteoid roots compared to normal roots, particularly under P stress. A portion of the carbon for citrate synthesis is derived from nonautotrophic CO2 fixation via PEPC in proteoid roots.

Journal Article↗

PubMedDate not supplied

Cvek pulpotomy: report of a case with five-year follow-up.

Partial pulpotomy (Cvek pulpotomy) is the treatment of choice for injured permanent incisor teeth with exposed vital pulp tissue and immature apices. This treatment preserves pulpal function, thus allowing continued root development. The present report describes the case of a permanent incisor with incomplete root end closure that underwent a Cvek pulpotomy, with subsequent apical closure. Five years post pulp therapy, the tooth remained symptom free.

Calcium Hydroxide↗

PubMed1991

Establishment of acellular extrinsic fiber cementum on human teeth. A light- and electron-microscopic study.

The present study describes for the first time the development of early acellular extrinsic fiber cementum (AEFC) until its establishment on human teeth. Precisely selected premolars with roots developed to 50%-100% of their final length were prefixed in Karnovsky's fixative and most of them were decalcified in EDTA. Their roots were subdivided into about 10 blocks each, cut from the mesial and distal root surfaces. Following osmication, these blocks were embedded in Epon and sectioned for light- and transmission electron microscopy. Some blocks were cut non-demineralized. From semithin stained sections, the density of the collagenous fiber fringe protruding from the root surface was measured by using the Videoplan-system. After initiation of this fiber fringe and its attachment to the dentinal root surface followed by mineralization, the fringe gradually increased in length and subsequently became mineralized. Fringe elongation and the advancement of the mineralization front appeared to progress proportionally. Thus, in all stages of AEFC development, a short fiber fringe covered the mineralized AEFC. Its density remained constant, irrespective of AEFC thickness. The latter gradually increased and reached an early maximum of 15-20 microns in the cervical region. At this stage, the AEFC fringe appeared to fuse with the future dentogingival or other collagen fibers of the tooth supporting apparatus. Mineralization of the fringe commenced with isolated, spherical or globular centers, which later fused with the mineralization front and became incorporated in AEFC.

Adolescent↗

PubMed1995

Accuracy of two dental and one skeletal age estimation method in Swedish adolescents.

The paper concerns the accuracy of two dental methods of age estimation based on the radiographic appearance of the root of the lower third molar. The first dental method tested was traditional with a subjective assessment of the root development stage and the second was a new method with a metric measurement of formed root length. Since previous studies have shown a relatively low precision for dentally based age estimation methods during adolescence, an additional independent indicator of chronological age was employed, namely skeletal maturity according to the atlas and method of Greulich and Pyle (Radiographic Atlas of Skeletal Development of the Hand and Wrist Stanford University Press, CA, 1959). The material was Swedish adolescents aged 12-19 years. It was found that all methods gave an overestimation of chronological age, with the highest overestimation, more than 1 year, for the two dental methods. A stepwise multiple regression analysis indicated that skeletal age alone explains 48% of the variation in estimated chronological age. It may be concluded that the accuracy of age estimations based on the lower third molars is quite uncertain during adolescence. Up to 18 years, it is preferable to use skeletal age alone as a predictor. Only a small increase in the explanation coefficient of age variation (3-4%) could be seen if digitized or subjectively estimated root lengths were added as predictors to the skeletal estimation.

Adolescent↗

PubMed1995

The development of Azospirillum as a commercial inoculant for improving crop yields.

Bacteria of the genus Azospirillum are nitrogen-fixing organisms that live in close association with plants in the rhizosphere. The Azospirillum-plant association leads to the enhanced development and yield of different host plants under appropriate growth conditions. This increase in yield is attributed mainly to an improvement in root development, an increase in the rate of water and mineral uptake by roots, and to a lesser extent, biological N(2) fixation. Worldwide data accumulated in the field over the past 20 years indicates that Azospirillum is capable of promoting the yield of agriculturally important crops in different soils and climatic regions. A.brasilense shows both chemotaxis and chemokinesis in response to temporal gradients of different chemoeffectors, thereby increasing the chance of root-bacterial interactions. Phytohormones synthesized by Azospirillum influence the host root respiration rate, metabolism and root proliferation and hence better the mineral and water uptake in inoculated plants. Positive effects of combined inoculation with Rhizobium have been reported for different legumes and were related to the favorable influence of Azospirillum on the nodule number, plant development, dry weight, and N(2) fixation. Additionally, A. brasilense produces the reserve material polyhydroxybutyrate comprising up to 70% of the cell dry weight This substance has received much attention recently as it can be extracted and formed into a biodegradable thermoplastic.

Journal Article↗

PubMed2007

Relation of aortic root dilatation and age in Marfan's syndrome.

AIMS: The main aim of this study was to describe the age at which pathological aortic root dilation occurs in patients with Marfan's syndrome (MFS). METHODS AND RESULTS: A total of 160 patients with MFS attending a regional cardiac centre were reviewed retrospectively. Dilation of the ascending aorta was diagnosed by comparing the maximum aortic sinus measurement with control data from the literature. We employed a Kaplan-Meier survival curve to estimate the age at which dilatation occurs. The mean age of the total group at presentation was 15.5 years (range 1.5-40 years). Skeletal abnormalities were present in 95%. Eye involvement was found in 18%. In the 115/160 patients with an abnormal aortic root, 78/115 (68%) developed aortic root dilatation before 19 years of age. From the Kaplan-Meier curve, it can be estimated that about 35% of the patients have aortic root dilatation already at the age of 5 years and 70% before the age of 20 years, and at least 80% by 40 years. There were 31 patients with normal aortic root when first seen but 24/31 (77%) developed aortic root dilatation before the age of 19 years and 7/31 (22.6%) after 19 years of age. Of those (seven patients) who developed new pathological aortic root dilatation after age 19 years, the age range was between 21 and 40 years with a mean of 27 years. Overall, 13 patients (8%) had surgery for aortic root replacement. CONCLUSION: Aortic root dilatation develops early in MFS and was present in 35% by the age of 5 years and 68% by 19 years. Even though new aortic root dilation is relatively rare, it is not possible to safely discharge patients with MFS as about one-third of the patients in our series who developed new pathological aortic root dilation did so after the age of 19 years.

Adolescent↗

PubMed2001

Ultrastructure of early mineral deposition during hyaline layer formation in rat molars.

There is no consensus on whether the first mineralized layer, the hyaline layer, that is juxtaposed to root dentine is a variety of dentine or cementum or even a tissue of epithelial origin. Some suggest that there is no intermediate tissue between the acellular extrinsic fibre cementum (AEFC) and the root dentine. Here, to study hyaline layer formation and mineralization we examined by transmission electron microscopy the early stages of root development in upper molars from 10 to 13 day old Wistar rats. In addition to conventionally processed material, undemineralized and unstained sections were examined, which showed the deposition of fine mineral crystals in contact with the mineralized surface of root dentine. Early mineralization of the hyaline layer occurred in the region of the inner basement membrane, which persisted between the inner cellular layer of Hertwig's epithelial root sheath and the outer mineralized root dentine. When the root sheath began its fragment, collagen fibrils from the developing periodontal ligament began to insert into the mineralising hyaline layer, which was 0.5-0.8 micron wide. As the fragmentation of the root sheath HERS increased, more collagen fibrils appeared intermingled with the mineralising hyaline layer. In more advanced stages, when the hyaline layer had become fully mineralized and the formation of the AEFC began, the hyaline layer could no longer be identified. Thus, the hyaline layer is clearly discernible at early stages of periodontal development. Subsequently, it is masked by intermingling of cementum and dentine and therefore it is not possible to detect it in the formed roots of rat molars.

Animals↗

PubMed1991

Acute pulpal-alveolar cellulitis syndrome V. Apical closure of immature teeth by infection control: case report and a possible microbial-immunologic etiology. Part 1.

Das with Matusow and Goodall previously noted the rapid clinical apexogenesis of nonvital immature permanent teeth that are involved with an acute endodontic cellulitis. This apexogenesis was achieved by control of infection and by nonspecific intracanal medication without the use of calcium hydroxide. The case report confirms the clinical observations. The experimental canine endodontic cellulitis in a Cebus primate was induced as an immunologic pulp infection with a facultative Streptococcus species. The noted epithelial proliferation and organization into lacelike strands and bilaminar loops, similar to Hertwig's epithelial root sheath in root development, appear to be immunologic and genetic in origin, with an acceleration of the root maturation process.

Animals↗