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PubMedDate not supplied

Enamel matrix derivative in periodontal reconstructive surgery. A new approach in periodontal regeneration.

True periodontal regeneration is the goal of any periodontal regenerative techniques. Cementum formation is a key event in the development of root and supporting periodontium. Due to its distribution, acellular cementum is the type most affected by early to moderate periodontitis. Studies over the past twenty years demonstrated that, enamel matrix proteins from the root sheath are involved in the formation of acellular, during tooth development. Thus the adjunctive use of enamel matrix derivatives in conjunction with regenerative periodontal surgery could possibly lead to true periodontal regeneration. The purpose of this article is to review the use of enamel matrix derivative in true periodontal regeneration.

Dental Cementum↗
PubMed2003

The root epidermis of Echium plantagineum L.: a novel type of pattern based on the distribution of short and long root hairs.

The great majority of angiosperm species form a group in which either every cell in the root epidermis produces a root hair, or the cells that produce these hairs are randomly distributed. We describe, for the first time, pattern in the root epidermal cells of a species within this group. The seedling root of Echium plantagineum L. (Boraginaceae) has an epidermis in which almost every cell produces a root hair, but these are of two types, short hairs (up to 200 micro m) and long hairs (>200 micro m), which are in separate cell files, with the cells bearing long hairs usually separated by one or two files of cells bearing short hairs; the epidermal cells with the long root hairs are longer than the epidermal cells with the short root hairs. The long root hairs are initiated and develop earlier than the short root hairs. Transverse sections of the region of the root which contains only developing long root hairs show that the hair cells are located above anticlinal walls between underlying cortical cells. We regard the distribution of root epidermal cells in E. plantagineum as a sub-type of this group. We discuss the possible evolution, from this sub-type, of another group that is characterised by hair cells and non-hair cells occurring in separate files.

Echium↗
PubMed2001

Rop GTPase: a master switch of cell polarity development in plants.

Cell polarity is fundamentally important to plant growth and development, yet the mechanism governing its development is understood poorly. Several studies have revealed a role for Rop GTPases in pollen polar tip growth. Rop is also localized to the future site of root hair development and the tip of root hairs, and expression of constitutively active Rop mutants impacts on the morphogenesis of tip-growing root hairs as well as on non-tip-growing cells. These findings highlight the importance of Rop as a common switch in cell polarity control in plants.

Cell Polarity↗
PubMed1988

Qualitative investigation of the postnatal development of axon and nerve fiber calibers in the ventral roots of rats.

The postnatal development of the ventral spinal roots of rats was studied with optical microscopic and morphometric methods. Adult rats show a craniocaudal decrease of axon and nerve fiber diameters which cannot be detected in younger animals. The bimodal differentiation of the nerve fiber populations occurs between the 15th and 20th day. Myelinated nerve fibers show a g ratio of 0.6 for all examined age groups.

Animals↗
PubMed2003

Root formation from transgenic calli of Ginkgo biloba.

The objective of this study was to produce Ginkgo biloba L. hairy roots for future investigations into the feasibility of producing terpenoids in differentiated cell cultures. Zygotic embryos of G. biloba were inoculated with the wild agropine-type Agrobacterium rhizogenes strain A4. Three months after bacterial infection, primordia-like nodular structures formed at the root wound sites and developed into tiny calli. Calli cultivated on hormone-free Lloyd and McCown (1980) solid medium were transferred onto Murashige and Skoog (1962) solid medium, and grew rapidly for the first few months. As browning appeared and growth slowed, calli were transferred onto Ball (1959) or White (1954) solid media. These calli became nodular with several nodules from which roots, displaying characteristic features of hairy roots, developed. Transgenic calli cultivated in agitated, hormone-free liquid media led to the formation of root meristems and root tips by a cyclic development process. Stable integration of the rolA, rolB and rolC genes into calli, mature roots and root meristem and root tip mixtures was confirmed by polymerase chain reaction (PCR). The absence of a 437 bp amplificate corresponding to the virD1 gene confirmed that there was no bacterial contamination of G. biloba tissues. The reverse transcription-PCR method was used to verify the expression of rolA and rolC genes in mature roots. Expression of rolA, rolB and rolC in root meristems and root tips was confirmed by 3' RACE-PCR analysis, which excluded amplification of possible rol gene transcripts produced by residual bacteria. This paper shows, for the first time, the feasibility of developing G. biloba roots from transformed calli.

Gene Expression Regulation, Plant↗
PubMed2006

A novel plant-specific family gene, ROOT PRIMORDIUM DEFECTIVE 1, is required for the maintenance of active cell proliferation.

Hypocotyl segments of Arabidopsis (Arabidopsis thaliana) produce adventitious roots in response to exogenously supplied auxin. root primordium defective 1 (rpd1) is a temperature-sensitive mutant isolated on the basis of impairment in this phenomenon. This study describes further phenotypic analysis of the rpd1 mutant and isolation of the RPD1 gene. When adventitious root formation was induced from the rpd1 explants at the restrictive temperature, cell proliferation leading to root promordia formation was initiated at the same time as in wild-type explants. However, development of the root primordia was arrested thereafter in the mutant. Temperature-shift experiments indicated that RPD1 exerts its function before any visible sign of root primordium formation. The expression patterns of the auxin-responsive gene DR5:beta-glucuronidase and the cytodifferentiation marker gene SCARECROW suggest that the rpd1 mutation interferes with neither axis formation nor cellular patterning at the initial stage of root primordium development. Taken together with the effect of the rpd1 mutation on callus cell proliferation, these data imply a role for RPD1 in prearranging the maintenance of the active cell proliferation during root primordium development. Positional cloning of the RPD1 gene revealed that it encodes a member of a novel protein family specific to the plant kingdom. Disruption of the RPD1 gene by a T-DNA insertion caused embryogenesis arrest at the globular to transition stages. This phenotype is consistent with the hypothesized function of RPD1 in the maintenance of active cell proliferation.

Amino Acid Sequence↗
PubMed2004

The ENHANCER OF TRY AND CPC1 gene acts redundantly with TRIPTYCHON and CAPRICE in trichome and root hair cell patterning in Arabidopsis.

The development of trichomes and root hairs in Arabidopsis provide useful models for the study of cell fate determination in plants. A common network of putative transcriptional regulators, including the small MYB proteins TRIPTYCHON (TRY) and CAPRICE (CPC), is known to influence the patterning of both cell types. Here, we used an activation tagging strategy to identify a new regulator, ENHANCER OF TRY AND CPC 1 (ETC1). The ETC1 sequence is similar to TRY and CPC, and ETC1 overexpression causes a reduction in trichome formation and excessive root hair production. The etc1 single mutant has no significant phenotype, but it enhances the effect of cpc and try on trichome and root hair development, which shows that ETC1 function is partially redundant with TRY and CPC. In addition, the etc1 try cpc triple mutant has novel phenotypes, revealing previously unrecognized roles for these regulators in epidermis development. An ETC1 promoter-reporter gene fusion is expressed in the developing trichome and non-hair cells, similar to the expression of TRY and CPC. These results suggest that ETC1, TRY, and CPC act in concert to repress the trichome cell fate in the shoot epidermis and the non-hair cell fate in the root epidermis.

Amino Acid Sequence↗
PubMed1996

Somatic embryogenesis and plantlet from petal cultures of pomegranate, Punica granatum L.

Somatic embryos were induced through petal cultures on MS supplemented with various growth adjuvants individually or in different combinations. Numerous embryoids formed from friable callus on MS with 5 mg/L of IAA, IBA or NAA developed only roots, but those formed on MS with 5 mg/L of BAP or KN developed shoots. Explants reared on MS supplemented with IAA (5 mg/L) and BAP (5 mg/L) though differentiated numerous embryoids but developed multilobed or fused cotyledons. However, callus induced on MS with IAA (1 mg/L) or IBA (1 mg/L) on subculturing in the same medium with half-strength salts and sucrose (4%) produced both roots and shoots resulting in plantlets.

Culture Techniques↗
PubMed1980

[Interrelationships between embryonal axons and lemmoblasts during the development of rat spinal nerve roots (electron-microscopic study)].

In order to elucidate the earliest interrelations of growing axons and lemmoblasts and the nature of the latter, a submicroscopic investigation of the rat spinal roots at places of their outlet from the neural tube was performed on the 11th and 13th day of embryonic development. The results obtained demonstrated that the spinal roots, both anterior and posterior, are formed by several fine (growing from the marginal layer of the neural tube) cords consisting of tightly packed "naked" axons with no signs of cellular elements inside them. These cords grow from the marginal layer of the neural tube towards periphery with resulting rupture of th tube's external limiting and basal membranes and formation of perforations; neither basal nor limiting membranes pass on the axonal surface. After leaving the neural tube for mesenchyma, the axonal cords get into connections with lemmoblasts that surround them completely. These cells are morphologically identical to poorly differentiated mesenchymal cells, situated nearby, and differ ultrastructurally from glioblasts of the neural tube (their processes form the external limiting membrane). A peculiar feature of lemmoblasts is the absence of a basal membrane and collagenous fibres around them; they are also absent, at this stage of development, in thin-walled capillaries formed from mesenchymal cells. In no case could be observed migration of glioblasts from the neural tube towards periphery and their transition on the cords of growing "naked" axons. The data obtained evidence in favour of the fact that lemmoblasts, surrounding the axonal cords, are formed at the place from poorly differentiated mesenchymal cells.

Animals↗
PubMed2003

Factors associated with root caries incidence in an elderly population.

OBJECTIVE: To identify baseline factors associated with future root caries development in an elderly population. BASIC RESEARCH DESIGN: Oral health and general health status examinations were carried out at baseline and after one and two years. In order to identify risk predictors of root caries with a different degree of robustness, three multiple logistic regression analyses where the dependent variables were one, two and three or more disease events were performed. PARTICIPANTS: Six hundred noninstitutionalised adults aged 70 in Niigata, Japan took part in the baseline examination. A total of 373 subjects were followed up for two years and identified as dentate at the two-year examination. RESULTS: During the period of study, 35.9% of subjects developed at least one new root caries lesion. The mean number of new root caries lesions per subject was 0.9 (sd = 1.7). Logistic regression analyses indicated that having one or more root D surface and mean LA > or = 3.6 mm were the most robust risk predictors, having two or more prosthetic crowns, non use of interdental brushes or dental floss and LB > or = 10(5) CFU/ml were moderately robust risk predictors, and a Body Mass Index < 20 was the least robust risk predictor. CONCLUSIONS: These findings suggest that oral health status is a good risk predictor, and poor general health indicated by a low Body Mass Index may also contribute to root caries occurrence in this elderly population.

Aged↗
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↗
PubMed2001

Modular construction of the protoderm and peripheral root cap in the "open" root apical meristem of Trifolium repens cv. Ladino.

Roots with open apical organization are defined by not having specific tiers of initial cells in the root apical meristem; those with closed apical organization have specific initial tiers to which all cell files can be traced. An example of the clear organization of closed roots is the development protocol of the root cap and protoderm. The key event in differentiating these tissues is the T-division, a periclinal division of the root cap/protoderm (RCP) initial that establishes a module. Each module comprises two packets, the protoderm and peripheral root cap. Consecutive T-divisions of the same RCP initial produce up to five modules on average in a lineage of cells in white clover (Trifolium repens cv. Ladino), with all lineages around the circumference of the root dividing in "waves" to form one module prior to the next. On average, clover has approximately 32 axial protoderm and peripheral root cap cells in each module, and 32 RCP lineages. The occurrence of RCP T-divisions in white clover, a root with open apical organization, and the subsequent modular construction of the root cap and protoderm, provides a link between open and closed roots and suggests a common developmental feature that most roots of seed plants may share independent of their root meristem organization type. The open apical organization of the white clover root varies from roots with closed apical organization in that the RCP initials occur in staggered positions instead of connected to discrete tiers, and the peripheral root cap and columella daughter cells form additional layers of cells. White clover also forms root hairs on all protoderm cells irrespective of their position relative to the underlying cortical cells.

Cell Division↗
PubMed2006

Is rootstock-induced dwarfing in olive an effect of reduced plant hydraulic efficiency?

We investigated the hydraulic architecture of young olive trees either self-rooted or grafted on rootstocks with contrasting size-controlling potential. Clones of Olea europea L. (Olive) cv 'Leccino' inducing vigorous scion growth (Leccino 'Minerva', LM) or scion dwarfing (Leccino 'Dwarf', LD) were studied in different scion/rootstock combinations (LD, LM, LD/LD, LM/LM, LD/LM and LM/LD). Shoots growing on LD root systems developed about 50% less leaf surface area than shoots growing on LM root systems. Root systems accounted for 60-70% of plant hydraulic resistance (R), whereas hydraulic resistance of the graft union was negligible. Hydraulic conductance (K = 1/R) of LD root systems was up to 2.5 times less than that of LM root systems. Total leaf surface area (A(L)) was closely and positively related to root hydraulic conductance so that whole-plant hydraulic conductance scaled by A(L) did not differ between experimental groups. Accordingly, maximum transpiration rate and minimum leaf water potential did not differ significantly among experimental groups. We conclude that reduced root hydraulic conductance may explain rootstock-induced dwarfing in olive.

Biological Transport↗
PubMed1999

Cell-specific production and antimicrobial activity of naphthoquinones in roots of lithospermum erythrorhizon

Pigmented naphthoquinone derivatives of shikonin are produced at specific times and in specific cells of Lithospermum erythrorhizon roots. Normal pigment development is limited to root hairs and root border cells in hairy roots grown on "noninducing" medium, whereas induction of additional pigment production by abiotic (CuSO4) or biotic (fungal elicitor) factors increases the amount of total pigment, changes the ratios of derivatives produced, and initiates production of pigment de novo in epidermal cells. When the biological activity of these compounds was tested against soil-borne bacteria and fungi, a wide range of sensitivity was recorded. Acetyl-shikonin and beta-hydroxyisovaleryl-shikonin, the two most abundant derivatives in both Agrobacterium rhizogenes-transformed "hairy-root" cultures and greenhouse-grown plant roots, were the most biologically active of the seven compounds tested. Hyphae of the pathogenic fungi Rhizoctonia solani, Pythium aphanidermatum, and Nectria hematococca induced localized pigment production upon contact with the roots. Challenge by R. solani crude elicitor increased shikonin derivative production 30-fold. We have studied the regulation of this suite of related, differentially produced, differentially active compounds to understand their role(s) in plant defense at the cellular level in the rhizosphere.

Journal Article↗
PubMed1966

Orientation of wheat seedling organs in relation to gravity.

Seedlings of wheat (Triticum aestivum L.) were grown in special holders that permitted the coleoptile and early roots to develop in moist air. The orientation of the organs of seedlings erect to gravity was compared with that of organs produced on a horizontal clinostat. Orientation was described by the angular position of each organ tip with reference to the axis of the embryo. Comparative tests were also made with barley, rye, and oat seedlings.The coleoptile of all species developed curvatures in 3 dimensions when geotropic responses were eliminated. The primary root was not precise in its positive geotropism. Seedlings grew on clinostats with much greater variations in the lateral orientation of the central root and with a tendency for it to curve away from the endosperm to a greater degree than in erect seedlings.The symmetry of root system in wheat was found to depend on a specific mechanism. Under the influence of gravity the earliest lateral roots were oriented in a plane at characteristic angles of about 57.5 degrees with the ideal primary root. The corresponding angles for lateral roots growing on clinostats were greater by about 47.5 degrees as a result of epinasty not previously reported in roots. This force also appeared to be active in the seminal roots of barley and rye but not of oats.The curvatures in coleoptiles grown without the directional effects of gravity correspond to the results of growth imbalance in Coleus stems in the absence of lateral transport of their auxin by gravity. Root epinasty appears to be based on auxin imbalance. Curvatures in the primary root are also interpreted as results of asymmetrical distribution of growth hormone.

Journal Article↗
PubMed2006

Mutations in the Diageotropica (Dgt) gene uncouple patterned cell division during lateral root initiation from proliferative cell division in the pericycle.

In angiosperms, root branching requires a continuous re-initiation of new root meristems. Through some unknown mechanism, in most eudicots pericycle cells positioned against the protoxylem change identity and initiate patterned division, leading to formation of lateral root primordia that further develop into lateral roots. This process is auxin-regulated. We have observed that three mutations in the Diageotropica (Dgt) gene in tomato prevent primordium formation. Detailed analysis of one of these mutants, dgt1-1, demonstrated that the mutation does not abolish the proliferative capacity of the xylem-adjacent pericycle in the differentiated root portion. Files of shortened pericycle cells found in dgt1-1 roots were unrelated to primordium formation. Auxin application stimulated this unusual proliferation, leading to formation of a multi-layered xylem-adjacent pericycle, but did not rescue the primordium formation. In contrast to wild type, auxin could not induce any cell divisions in the pericycle of the most distal dgt1-1 root-tip portion. In wild-type roots, the Dgt gene promoter was expressed strongly in lateral root primordia starting from their initiation, and on auxin treatment was induced in the primary root meristem. Auxin level and distribution were altered in dgt1-1 root tissues, as judged by direct auxin measurements, and the tissue-specific expression of an auxin-response reporter was altered in transgenic plants. Together, our data demonstrate that the Dgt gene product, a type-A cyclophilin, is essential for morphogenesis of lateral root primordia, and that the dgt mutations uncouple patterned cell division in lateral root initiation from proliferative cell division in the pericycle.

Arabidopsis↗
PubMed2005

In-situ monitoring of microbial biomass in wetland mesocosms.

The objective of the present investigation has been to combine tracer principles and a hydrolytic microbial activity assay using fluorescein diacetate to monitor changes in microbial biomass within subsurface flow wetland mesocosms. The mesocosm hydrolytic activity was referenced to activated sludge concentrations treating a typical domestic wastewater at full scale. Microbial biomass activity levels within four laboratory wetland mesocosms treating a synthetic domestic wastewater were routinely monitored over a 21-week period of plant growth and rhizosphere development. Although above ground plant mass and tracer dispersion numbers suggested progressive root zone development, plant growth did not result in any measurable enhancement in microbial activity when compared to a mesocosm operating without plants. Dispersion numbers also suggested a reduction in the mass transport kinetics in these planted mesocosms. In-situ biomass monitoring enabled the assessment of a characteristic response in terms of the steady-state food to microorganism (F/M) ratio that was observed in mesocosms receiving both low and high organic loading. Wetland treatment performance is sensitive to the degree to which bed volume is exploited in terms of wastewater flow to regions of bioactivity. The in-situ reactive tracer technique for mesocosm biomass monitoring provided an assessment of the collective substratum and rhizosphere microbial biomass in direct contact with wastewater contaminants. Thus, in-situ biomass monitoring has application in further understanding of plant function and strategies for plant implementation in wetland research and development.

Bacteria↗
PubMed1993

Preventive aspects of root caries.

Several factors are responsible for an increasing number of exposed root surfaces, resulting in a higher root caries risk. Assuming that the pathogenesis of root and enamel caries have strong similarities, the same preventive methods could be applied for root caries and for enamel caries. However, due to a higher critical pH for dentine/cement, the prevention for root caries should be more intensive. Several studies indicate that fluoride is the cornerstone of root caries prevention. In addition, antimicrobials, in particular chlorhexidine, can be helpful in inhibiting root caries development. This paper proposes the use of three different risk categories for root caries to help adjust the intensity of preventive measures to the needs of the individual patient.

Humans↗