Root Mineral Research Articles

Therapeutic delivery of calcitonin to inhibit external inflammatory root resorption. II. Influence of calcitonin binding to root mineral.

Experimentally-induced external inflammatory tooth-root resorption can be inhibited by therapeutic doses of calcitonin. Such doses can be delivered by an intrinsically slow diffusion pathway, from a reservoir in endodontically-debrided root canals, via the dentinal tubules. While the kinetics of this journey have been followed in an earlier report, the binding characteristics of calcitonin to the tooth mineral, which will be responsible, in part, for these kinetics, have not been reported before. The current study examines the binding potential of calcitonin to root mineral and addresses the potential role of non-specific binding proteins. A modified Scatchard plot indicated that a simple non-reactive type of ligand binding exists between calcitonin and root mineral, represented by a small number of identical binding sites. This interaction is both strong and reversible. Furthermore, it appears to be time-dependent with more time being required for the residual ligands to interact with the diminishing numbers of free calcitonin-binding sites. While preloaded [125I]-calcitonin could be incompletely (75-91%) displaced from dental-root material by non-radioactive calcitonin, its release was slow over 23 h. Calcitonin was four times as effective as bovine-serum albumin in competing for common "calcitonin binding sites" on macerated dental-root material. Thus, even in the presence of extraneous protein, calcitonin will bind tightly but reversibly to tooth-root material, making it a good candidate for therapeutically protracted delivery to external root surfaces from root canals.

Fine root mineralization, soil organic matter and exchangeable cation dynamics in slash and burn agriculture in the semi-arid northeast of Brazil

The objective of this study was to understand the causes of crop productivity decline on a soil cultivated by the slash and burn method. The contribution of ashes, fine roots, and soil organic matter (SOM) mineralization to the pool of available nutrients of a nutrient-poor Haplustox of the semi-arid zone of northeastern Brazil was documented. Ashes were the most important input of nutrients to the soil. The burning of the vegetation debris produced 11 Mg ha −1 of ash containing considerable quantities of Ca and K, and some N, Mg and P. The ashes, in general, contained more Ca and Mg, and less N and K, than the estimated requirements of the cassava ( Manihot esculenta) crop during the cultivation cycle, whereas the P in ashes was equivalent to the crop P uptake. About 65% of the fine roots from the native vegetation decomposed in the soil during the first rainy season after the slash and burn, contributing Ca, N, and Mg to stores of available nutrients, with limited supply of K and P. The SOM content decreased with cultivation. The losses ranged from 4 to 16%, 6–18%, and 10–20%, for C, N and organic P, respectively. The sum of exchangeable cations, base saturation and pH increased after the burn, whereas the exchangeable Al and Al saturation strongly decreased, promoting better growing conditions for the cassava crop, particularly during the first years of the cultivation cycle. The soil properties reverted to pre-burn conditions within two or three crop years, productivity declined and the field was abandoned to natural fallow.

Uptake of Nutrients in a Plantation ofAcacia mangiumin Relation to Decrease in Soil Amounts

Abstract Amounts of total nitrogen, phosphorus, potassium, calcium, magnesium, manganese, and sodium in the humus layer and plant-available or exchangeable nutrients in the top 30 cm of the soil were determined before planting and in a 45-month-old plantation of Acacia mangium. Amounts were lower in the plantation than before planting owing to plant uptake and leaching. However, for potassium and calcium the difference was much smaller than the amounts in the plantation biomass, indicating that the plants had taken up nutrients from soil depths below 30 cm or had utilized other sources of nutrients. The other main sources of nutrients were mineralization of dead logs, big branches, and roots, none of which had been included in the humus sampling, and chemical weathering of minerals. The supply of plant nutrients through atmospheric input was low, and there was a negligible input of nutrients dissolved in laterally flowing water because the investigated plot was situated near the water divide. The investig...

PEG stress altered citrus root and leaf mineral concentrations

Abstract An experiment was conducted to study the effects of polyethylene glycol (PEG) on citrus growth and mineral composition. Seedlings of 7 citrus rootstock cultivars were treated with three osmotic potential levels (‐0.10, ‐0.20, and ‐0.35 MPa) of PEG for five months under greenhouse conditions. Increasing the concentration of PEG in the nutrient solution proportionally reduced root and shoot growth in all rootstocks. Although roots were in direct contact with PEG, their growth was less affected by PEG treatments than that of shoots. Seedling growth was reduced the most in Carrizo citrange and Milam lemon. Significant differences in root and leaf mineral concentrations among cultivars were found under PEG stressed and non stressed conditions. Furthermore, no consistent relationship in mineral absorption, translocation and accumulation seemed to exist between citrus roots and leaves. Root and leaf mineral concentrations were also significantly altered by PEG in all rootstock cultivars. Nitrogen (N), p...

Effect of Salinity on Leaf and Root Mineral Contents of Some Citrus Rootstocks and Scions

Effect of Salinity on Leaf and Root Mineral Contents of Some Citrus Rootstocks and Scions

Relationship between mineral coating on roots and yield performance of wheat under waterlogging stress

Waterlogging stress limits the productivity of winter wheat (Triticum aestivum L. emend. Thell.) in many parts of the world. When wheat is grown under waterlogged conditions, a reddish-brown mineral coating can form on the epidermal surface of the roots. In wetland plants such as rice, the amount of mineral coating formed on root surfaces is positively related to yield. This study was conducted to determine whether mineral coating on the roots of wheat is related to yield potential under waterlogged conditions. Root mineral coatings formed under waterlogged conditions were studied in 12 cultivars and two breeding lines over three years of greenhouse pot studies. Soil redox potential in the waterlogged treatment ranged between -46 and 171 mV, and grain yield was suppressed by 28-49% compared to well-drained controls. Mineral coating formed on the roots from the waterlogged treatment was determined to be composed primarily of iron, based on ICP elemental analysis, iron-specific staining, and ion-mapping by scanning electron microscopy using an X-ray detector. Of 11 elements quantified by ICP spectroscopy, six were significantly affected by waterlogging treatment, and three of these, Fe, Mn and P, were well-correlated negatively to yield. Aerenchyma formation in the heavily coated waterlogged roots appeared to disrupt the internal root structure, and exceeded 40% of crosssectional area in one cultivar. Unlike rice, which shows a positive relationship between oxygen release from roots, grain yield and mineral coating, in winter wheat, the amount of mineral coating is negatively related to grain yield under waterlogged conditions.

Salinity tolerance of citrus rootstocks: Effects of salt on root and leaf mineral concentrations

The effects of three concentrations of sodium chloride (NaCl) on seven citrus rootstocks were studied under greenhouse conditions. Leaf and root mineral concentrations and seedling growth were measured. Sodium chloride was added to the nutrient solution to achieve final osmotic potentials of −0.10, −0.20, and −0.35 MPa. Increasing the concentration of NaCl in the nutrition solution reduced growth proportionally and altered leaf and root mineral concentrations of all rootstocks. Significant differences in leaf and root mineral concentration among rootstocks were also found under stressed and non-stressed conditions. Salinity caused the greatest growth reduction in Milam lemon and trifoliate orange and the least reduction in sour orange and Cleopatra mandarin. No specific nutrient deficiency was the sole factor reducing growth and causing injury to citrus rootstocks. Sodium chloride sensitivity of citrus rootstocks in terms of leaf burn symptoms and growth reduction could be attributed more to Cl than to Na. Sodium and Cl concentrations were greater in the leaves than in the roots, particularly at the medium and high salinity levels. Root Cl was not useful for assessing injury because no differences were found in root Cl concentrations among rootstocks. Increasing salinity level did not affect the level of N and Ca in the roots but did reduce N and Ca levels in the leaves. No relationship in mineral concentration or accumulation seemed to exist between citrus leaves and roots. At the −0.10 MPa salinity level, sour orange, rough lemon, and Milam were not able to exclude either Na or Cl from their leaves. Trifoliate orange and its two hybrids (Swingle citrumelo and Carrizo citrange) excluded Na at the lowest salt level used, but were unable to exclude Na at the higher salinity levels. Similarly, Cleopatra mandarin excluded Cl at the lowest salt level, but was not able to exclude Cl at higher salt concentrations. Hence, the ability of citrus rootstocks to exclude Na or Cl breaks down at higher salt concentrations.

Influence of aluminium and nitrogen on uptake and distribution of minerals in beech roots (Fagus sylvatica)

Beech seedlings (Fagus sylvatica L. provenance Vastra Torup) were grown in nutrient solution at low pH (4.2) and exposed to AlCl3 and different concentrations of nitrogen. The effects of AlCl3 and nitrogen on uptake of Ca2+ (45Ca) and H2PO4- (32P) in roots of intact beech were studied. Crossections of roots were analyzed with respect to element concentrations, by use of Mikro-PIXE (particle induced X-ray emission). The distribution of Al, Ca, P, Mg, K, and S was analysed. The experiments were designed to evaluate the effects of aluminium on localization of elements in plant root tissue.

The effects of premature deciduous molar loss on the succeeding premolars

By means of panoramic radiographs of 76 patients we investigated the development and eruption of lower premolars following premature loss of their deciduous predecessor. Following extraction of deciduous molars the mineralization of the bicuspids was accelerated. The eruption of the respective bicuspids took place earlier than expected. During eruption root length was shorter than usual for that stage of development. Although the bicuspids reached occlusion earlier than normal, root mineralization continued to normal length.

Root nitrogen transformation and mineral composition in selected forage legumes

SummaryA study was conducted at Debre Zeit, Ethiopia to examine the differences in mineral composition, root N contents and their rates of transformation in the soil of different species of four genera of forage legumes,Trifolium steudneri(ILCA D/Z),Trifolium steudneri(Shola),Vicia dasycarpa(ILCA 6795),Vicia benghalensis, Lablab purpureuscv. Rongai,Lablab purpureuscv. Highworth,Medicago scutellatacv. Snail andMedicago truncatulacv. Barrel.M. truncatulacv. Barrel had higher N and P values thanM. scutellatain both roots and tops. Root N contents of the legumes ranged from 2·43% forViciato 0·87% forLablab. These differences were also reflected in the rates of organic root N transformation in soil as determined in laboratory incubation studies.The P concentration in the tops of the legumes ranged from 0·32% inViciato 0·14% inMedicagospp. The observed P concentration in theMedicagospecies suggests a low internal P requirement. Potassium concentrations in theTrifoliumspecies were much higher than the average for all legumes.The results suggest that theViciaspecies used in this study could contribute a considerable amount of N to subsequent crops even when the tops are not returned to the soil. Also, theMedicagospecies are more likely to thrive better under low soil P conditions than the other legumes.

Improvement of the Caries Resistance of Human Dental Roots by a Two-step Conversion of the Root Mineral into Fluoridated Hydroxylapatite

Roots of extracted human molars were treated for both 10 and 30 min with a saturated solution of dicalcium phosphate dihydrate (DCPD) of pH 2.4 and subsequently with a 5.3 mmol.L-1 solution of sodium fluoride of pH 7.0. The objective of these combined treatments was to convert the highly-soluble root mineral into the less-soluble fluoridated hydroxylapatite, with DCPD as an intermediate, to improve caries resistance. The mineral content of the surface layer was not affected in a significant way. Roots treated in this way were subjected to 50 mmol.L-1 acetate buffer solutions of pH 5.5 and with pIOHA-values of 112, 116, and 122. The proportional reduction of the rate of demineralization (Vdem) of similarly treated roots subjected to buffer solutions of pIOHA 112 and 116 appeared to be equal initially. Since fluoridated hydroxylapatite is insoluble under these conditions, these findings are in agreement with expectations. The reduction of V dem amounted to about 45 and 70% for roots treated for 10 and 30 min, respectively. When roots were treated for 10 and 30 min and then exposed to buffer solutions with a pIOHA 122, reductions of V dem of about 30 and 55%, respectively, were found. Conversion of the root mineral into fluoridated hydroxylapatite can eliminate, in principle, the existing difference in caries susceptibility of the root and of the dental enamel.

Influence of aluminium and nitrate on root growth and mineral nutrition of Norway spruce (Piceaabies) seedlings

Norway spruce (Piceaabies) (L.) Karst.) seedlings were grown in nutrient solutions containing 334, 664, or 1000 μmol•dm−3 nitrate in the presence or absence of 500 μmol•dm−3 aluminium. Over 7 days the rate of root elongation was severely reduced by Al, irrespective of the NO3 concentration. Root elongation was inhibited within 12 h of exposure and this was associated with a displacement of Ca and Mg by Al in the roots. After 35 days, Al significantly reduced Mg and Ca contents of roots and needles. This effect was independent of the NO3 supply. Root growth was stimulated at 1000 μmol•dm−3 NO3 compared with 664 and 334 μmol•dm−3 NO3. This stimulation was inhibited by 500 μmol•dm−3 Al. The results show that spruce seedlings are sensitive to Al, and that NO3 does not modify the toxicity of Al.

Root turnover in a beech and a spruce stand of the Belgian Ardennes

The theoretical basis of fine root turnover estimation in forest soils is discussed, in relation to appropriate experimental techniques of measurement. After sequential coring, the correct expression is the sum of significant positive increments of live and dead roots of the various diameter categories, to which the transfer of dead roots to organic matter derived from roots, OMDR, has to be added. This should not be confounded with dead root mineralization. The transfer rates should first be estimated in root dimensions and not in weight of dry matter.

The demineralization of human dental roots in the presence of fluoride.

Intact roots of human molars, which had not been exposed to the oral environment, were exposed to buffer solutions of pH 5.5, which contained, besides calcium and phosphate, various concentrations of fluoride. Densitometric measurements on contact-microradiograms of transverse sections of these roots produced data which were used to calculate the rate of demineralization (Vdem). Vdem appeared to be reduced with increasing fluoride concentration and with decreasing pIOHA (i.e., the negative logarithm of the ionic product of hydroxyapatite) of the buffer solution. In addition, it was observed that, after some days of exposure, remineralization started to occur within the surface layer at some micron from the outer surface and that the region within which remineralization took place was extended inward with increasing time of exposure. These data suggest that fluoride is effective in the prevention of root surface caries. The mechanism of the interaction of fluoride with the root mineral is discussed.

Kaolinite, Opal-CT, and Clinoptilolite in Altered Tuffs Interbedded with Lignite in the Jackson Group, Texas

AbstractThe mineralogy of partially kaolinized strata interbedded with lignite at the San Miguel mine, Atascosa County, Texas, was investigated by X-ray powder diffraction and optical and scanning electron microscopy. The San Miguel lignite occurs in the lower Jackson Group (late Eocene) of southern Texas. Based on mineralogical and micromorphological data, some of these clay partings are probably volcanic in origin and were exposed to variable degrees of in situ kaolinization in a swamp environment. Coexistence of kaolinite, clinoptilolite, and opal-CT in several of these strata suggests that the partially kaolinized volcanic layers were subjected to a subsequent resilication process following burial. Kaolinite is the dominant mineral in the oldest and most kaolinized volcanic layer (underclay) below the lowest lignite bed (seam D). The kaolinite exhibits a well-developed vermicular morphology. The youngest volcanic layer, which occurs stratigraphically above the uppermost lignite seam, is characterized by pseudomorphs of volcanic glass shards and consists mainly of clinoptilolite. Movement of siliceous ground water from this layer to the underlying strata apparently provided silica-rich solutions from which opal-CT and large (as long as 300 μm) euhedral crystals of clinoptilolite precipitated in the fossilized plant roots, veinlets, and fractures within the underlying strata. Micromorphological relationships between the Sirich (opal-CT and clinoptilolite) and sulfide (marcasite and pyrite) minerals in the fossil roots and fractures suggest that the marcasite formed before and pyrite after the resilication process.

The mineral solubility of human tooth roots

Whole roots of molars that had never been exposed to the mouth were exposed to calcium and phosphate-containing buffer solutions with discrete values of pI OHA [i.e. −log( a Ca 2− 10 · a PO 4 3− 6· a OH− 2)] at various pH. From densitometric measurements on contact-microradiographs of transverse sections of the roots the rate of demineralization ( V dcm) was calculated. V dem changed non-linearly as a function of pI OHA and became zero at a pI OHA-value of 105.3 ± 0.4; this is substantially lower than the corresponding value of 118 ± 1 for enamel. Thus root mineral is more soluble than enamel mineral. The critical pH for root caries appears to be about 6.7, provided that the plaque fluid follows about the same pH-pI OHA− pathway as acidified saliva.

Imbalanced forest ecosystems: Assessments and consequences

Few ecosystems can maintain an ideal balance of available resources for primary producers, decomposing organisms, and consumers. When nutrition is optimal for plants, their tissue may be toxic for many consumers and their detritus nutritionally imbalanced for decomposers. Even conditions favoring high rates of primary production soon lead to limitation in light and possibly other resources. Because of the integrated nature of ecosystems, stress induced in one part permeates the entire system. With chronic stress induced by climatic change or air pollution, we might expect reductions in canopy leaf area, decomposition rates, and root mineral uptake, and increases in herbivory, pathological activity, and leaching of material into or through the rooting zone. Each of the six responses can be simply assessed. As a general index of stress to forest ecosystems, we may monitor changes in the ability of folaige to produce wood. Below a particular level of production, trees become susceptible to a variety of insects and diseases. Through an experimental approach, we can identify the relative importance of constraining factors and predict the consequences of management options.

Influence of N Source, N Rate, and K Rate on the Yield and Mineral Concentration of Sweet Potato

Abstract ‘Jewel’ sweet potatoes [Ipomoea batatas (L.) Lam.] were grown during 2 seasons to evaluate 3 N sources, 3 K rates, and 2 N rates on a sandy loam soil. Nitrogen source did not influence yield; however, NaNO3 significantly increased foliar and root Na concentrations over those obtained with NH4NO3 or Ca(NO3)2. Higher yields were obtained with 140 kg K/ha than with 70 or 280 kg K/ha and 101 kg N/ha than with 202 kg N/ha. No foliar or root mineral concentrations were deficient. Nitrogen, P, Ca, and Mg concentrations were lower in root than foliar tissues.

Formation of the permanent dentition in Arikara Indians: timing differences that affect dental age assessments.

This report concerns one problem encountered with application of American white dental formation standards to age assessment of sub-adults of archaeological context. Dental ages for eight mandibular permanent teeth and maxillary central and lateral incisors of Arikara Indian immature skeletons were determined according to degree of crown or root mineralization. Ages assigned to the various teeth of the same individual were compared. They showed similarities as well as patterned differences. First premolar, second premolar, and mandibular incisor ages closely approximated one another. In relation to this complex, dental ages for maxillary incisors and mandibular second molars were older by 0.5 to 1.1 years. Developmental ages assigned to individuals on the basis of third molars showed relative advancement by more than 2 years. The systematic occurrence of these observations reflects more than just individual variability; it shows the presence of population differences in tooth-formation timing. Timing differences complicate assessment of dental ages needed for growth or demographic studies.

Determination of the mineral content and the transparency of the root dentine of human teeth

One hundred and fifty-six teeth were extracted from corpses aged between 15 and 79 years. Of these, 101 teeth were selected for measurement of the mineral content of the root by photon beam absorption. Six or seven cross-sections were measured in each root, and the mean values calculated for the apical, medial, and coronal part within each decade. Further, 20 selected teeth were embedded in methacrylate and the length of the zone of transparency determined in longitudinal sections. There was no significant age dependency of the root's mineral content. There was no correlation between the extent of transparency and the mineral content.