Distribution of calcium (Ca) and magnesium (Mg) in the leaves of Brassica rapa under varying exogenous Ca and Mg supply

Background and Aims Leafy vegetable Brassica crops are an important source of dietary calcium (Ca) and magnesium (Mg) and represent potential targets for increasing leaf Ca and Mg concentrations through agronomy or breeding. Although the internal distribution of Ca and Mg within leaves affects the accumulation of these elements, such data are not available for Brassica. The aim of this study was to characterize the internal distribution of Ca and Mg in the leaves of a vegetable Brassica and to determine the effects of altered exogenous Ca and Mg supply on this distribution. Methods Brassica rapa ssp. trilocularis ‘R-o-18’ was grown at four different Ca:Mg treatments for 21 d in a controlled environment. Concentrations of Ca and Mg were determined in fully expanded leaves using inductively coupled plasma-mass spectrometry (ICP-MS). Internal distributions of Ca and Mg were determined in transverse leaf sections at the base and apex of leaves using energy-dispersive X-ray spectroscopy (EDS) with cryo-scanning electron microscopy (cryo-SEM). Key Results Leaf Ca and Mg concentrations were greatest in palisade and spongy mesophyll cells, respectively, although this was dependent on exogenous supply. Calcium accumulation in palisade mesophyll cells was enhanced slightly under high Mg supply; in contrast, Mg accumulation in spongy mesophyll cells was not affected by Ca supply. Conclusions The results are consistent with Arabidopsis thaliana and other Brassicaceae, providing phenotypic evidence that conserved mechanisms regulate leaf Ca and Mg distribution at a cellular scale. The future study of Arabidopsis gene orthologues in mutants of this reference B. rapa genotype will improve our understanding of Ca and Mg homeostasis in plants and may provide a model-to-crop translation pathway for targeted breeding.

Inorganic synthesis of Fe-Ca-Mg carbonates at low temperature

A set of free-drift experiments was undertaken to synthesize carbonates of mixed cation content (Fe, Ca, Mg) from solution at 25 and 70 degrees C to better understand the relationship between the mineralogy and composition of these phases and the solutions from which they precipitate. Metastable solid solutions formed at 25 degrees C which are not predicted from the extrapolation of higher temperature equilibrium assemblages; instead, solids formed that were intermediary in chemical composition to known magnesite-siderite and dolomite solid solutions. A calcite-siderite solid solution precipitated at 25 degrees C, with the percentage of CaCO3 in the solid being proportional to the aqueous Ca/Fe ratio of the solution, while Mg was excluded from the crystal structure except at relatively high aqueous Mg/Ca and Mg/Fe ratios and a low Ca content. Alternatively, at 70 degrees C Mg was the predominant cation of the solid solutions. These results are compatible with the hypothesis that the relative dehydration energies of Fe, Ca and Mg play an important role in the formation of mixed cation carbonates in nature. (C) 2009 Elsevier Ltd. All rights reserved.

Genetical and comparative genomics of Brassica under altered Ca supply identifies Arabidopsis Ca-transporter orthologs

Although Ca transport in plants is highly complex, the overexpression of vacuolar Ca2+ transporters in crops is a promising new technology to improve dietary Ca supplies through biofortification. Here, we sought to identify novel targets for increasing plant Ca accumulation using genetical and comparative genomics. Expression quantitative trait locus (eQTL) mapping to 1895 cis- and 8015 trans-loci were identified in shoots of an inbred mapping population of Brassica rapa (IMB211 × R500); 23 cis- and 948 trans-eQTLs responded specifically to altered Ca supply. eQTLs were screened for functional significance using a large database of shoot Ca concentration phenotypes of Arabidopsis thaliana. From 31 Arabidopsis gene identifiers tagged to robust shoot Ca concentration phenotypes, 21 mapped to 27 B. rapa eQTLs, including orthologs of the Ca2+ transporters At-CAX1 and At-ACA8. Two of three independent missense mutants of BraA.cax1a, isolated previously by targeting induced local lesions in genomes, have allele-specific shoot Ca concentration phenotypes compared with their segregating wild types. BraA.CAX1a is a promising target for altering the Ca composition of Brassica, consistent with prior knowledge from Arabidopsis. We conclude that multiple-environment eQTL analysis of complex crop genomes combined with comparative genomics is a powerful technique for novel gene identification/prioritization.

Euthydemoss of Bactria

Euthydemos I (ca. 260–200 bce) was king of Bactria from around 230. He founded a dynasty which, most notably under his son Demetrios I, extended the control of the Greco-Bactrian kings south of the Hindu Kush into Arachosia and India.

Using Social Network Research in HRM: Scratching the surface of a fundamental basis of HRM

This article is the guest editors' introduction to a special issue on using Social Network Research in the field of Human Resource Management. The goals of the special issue are: (1) to draw attention to the points of integration between the two fields, (2) to showcase research that applies social network perspectives and methodology to issues relevant to HRM and (3) to identify common challenges where future collaborative efforts could contribute to advancements in both fields.

Short-term effects of manipulated increase in acid deposition on soil, soil solution chemistry and fine roots in Scots pine (Pinus sylvestris) stand on a podzol

A manipulated increase in acid deposition (15 kg S ha(-1)), carried out for three months in a mature Scots pine (Pinus sylvestris) stand on a podzol, acidified the soil and raised dissolved Al at concentrations above the critical level of 5 mg l(-1) previously determined in a controlled experiment with Scots pine seedlings. The induced soil acidification reduced tree fine root density and biomass significantly in the top 15 cm of soil in the field. The results suggested that the reduction in fine root growth was a response not simply to high Al in solution but to the depletion of exchangeable Ca and Mg in the organic layer, K deficiency, the increase in NH4:NO3 ratio in solution and the high proton input to the soil by the acid manipulation. The results from this study could not justify the hypothesis of Al-induced root damage under field conditions, at least not in the short term. However, the study suggests that a short exposure to soil acidity may affect the fine root growth of mature Scots pine.

Molecular genetic differentiation in earthworms inhabiting a heterogeneous Pb-polluted landscape

A Pb-mine site situated on acidic soil, but comprising of Ca-enriched islands around derelict buildings was used to study the spatial pattern of genetic diversity in Lumbricus rubellus. Two distinct genetic lineages ('A' and 'B'), differentiated at both the mitochondrial (mtDNA COII) and nuclear level (AFLPs) were revealed with a mean inter-lineage mtDNA sequence divergence of approximately 13%, indicative of a cryptic species complex. AFLP analysis indicates that lineage A individuals within one central 'ecological island' site are uniquely clustered, with little genetic overlap with lineage A individuals at the two peripheral sites. FTIR microspectroscopy of Pb-sequestering chloragocytes revealed different phosphate profiles in residents of adjacent acidic and calcareous islands. Bioinformatics found over-representation of Ca pathway genes in ESTPb libraries. Subsequent sequencing of a Ca-transport gene, SERCA, revealed mutations in the protein's cytosolic domain. We recommend the mandatory genotyping of all individuals prior to field-based ecotoxicological assays, particularly those using discriminating genomic technologies.

Effects of calcium chloride and sodium hexametaphosphate on certain chemical and physical properties of soymilk

Soymilks with sodium hexametaphosphate (SHMP) (0% to 1.2%) and calcium chloride (12.50, 18.75, and 25.00 mM Ca),were analyzed for total Ca, Ca ion concentration, pH, kinematic viscosity, particle diameter, and sediment after pasteurization. Higher added Ca led to significant (P <= 0.05) increases in Ca ion concentration and significant (P <= 0.05) decreases in pH. At certain levels of SHMP, higher concentrations of added Ca significantly increased (P <= 0.05) kinematic viscosity, particle diameter, and sediment. Increasing SHMP concentration reduced Ca ion concentration, particle diameter, and dry sediment content, but reduced kinematic viscosity of samples (P <= 0.05). Adding SHMP up to 0.7% influenced pH of soymilk in different ways, depending on the level of Ca addition. When the pH of Ca-fortified soymilk was adjusted to a higher level, ionic Ca decreased as pH increased. Ihere was a negative linear relationship between the logarithm of ionic Ca concentration and the adjusted pH of the soymilk. Ionic Ca appeared to be a good indicator of thermally induced sediment formation, with little sediment being produced if ionic Ca was maintained below 0.4 mM.

Differences in the activity of the muscles in the forearm of individuals with a congenital absence of the hand

The spectral content of the myoelectric signals from the muscles of the remnant forearms of three persons with congenital absences (CA) of their forearms was compared with signals from their intact contra-lateral limbs, similar muscles in three persons with acquired losses (AL) and seven persons without absences [no loss (NL)]. The observed bandwidth for the CA subjects was broader with peak energy between 200 and 300 Hz. While the signals from the contra-lateral limbs and the AL and NL subjects was in the 100-150 Hz range: The mean skew of the signals from the AL subjects was 46.3 +/- 6.7 and those with NL of 45.4 +/- 8.7, while the signals from those with CAs had a skew of 11.0 +/- 11. The structure of the muscles of one CA subject was observed ultrasonically. The muscle showed greater disruption than normally developed muscles. It is speculated that the myographic signal reflects the structure of the muscle. which has developed in a more disorganized manner as a result of the muscle not being stretched by other muscles across the missing distal joint, even in the muscles that are used regularly to control arm prostheses.

Periodic time series modeling of environmental proxy records with guaranteed positive growth rate estimation

Identifying a periodic time-series model from environmental records, without imposing the positivity of the growth rate, does not necessarily respect the time order of the data observations. Consequently, subsequent observations, sampled in the environmental archive, can be inversed on the time axis, resulting in a non-physical signal model. In this paper an optimization technique with linear constraints on the signal model parameters is proposed that prevents time inversions. The activation conditions for this constrained optimization are based upon the physical constraint of the growth rate, namely, that it cannot take values smaller than zero. The actual constraints are defined for polynomials and first-order splines as basis functions for the nonlinear contribution in the distance-time relationship. The method is compared with an existing method that eliminates the time inversions, and its noise sensitivity is tested by means of Monte Carlo simulations. Finally, the usefulness of the method is demonstrated on the measurements of the vessel density, in a mangrove tree, Rhizophora mucronata, and the measurement of Mg/Ca ratios, in a bivalve, Mytilus trossulus.

Feasibility of using dialysis for determining calcium ion concentration and pH in calcium-fortified soymilk at high temperature

Dialysis was performed to examine some of the properties of the soluble phase of calcium (Ca) fortified soymilk at high temperatures. Dialysates were obtained while heating soymilk at temperatures of 80 and 100 °C for 1 h and 121 °C for 15 min. It was found that the pH, total Ca, and ionic Ca of dialysates obtained at high temperature were all lower than in their corresponding nonheated Ca-fortified soymilk. Increasing temperature from 80 to 100 °C hardly affected Ca ion concentration ([Ca2+]) of dialysate obtained from Ca chloride-fortified soymilk, but it increased [Ca2+] in dialysates of Ca gluconate-fortified soymilk and Ca lactate-fortified soymilk fortified with 5 to 6 mM Ca. Dialysates obtained at 100 °C had lower pH than dialysate prepared at 80 °C. Higher Ca additions to soymilk caused a significant (P≤ 0.05) reduction in pH and an increase in [Ca2+] of these dialysates. When soymilk was dialyzed at 121 °C, pH, total Ca, and ionic Ca were further reduced. Freezing point depression (FPD) of dialysates increased as temperature increased but were lower than corresponding soymilk samples. This approach provides a means of estimating pH and ionic Ca in soymilks at high temperatures, in order to better understand their combined role on soymilk coagulation.

The Spanish Ambassador and Samuel Daniel's Vision of the Twelve Goddesses: A New Document [with text]

The performance of Samuel Daniel's masque The Vision of the Twelve Goddesses at court on January 8, 1604 took place in the midst of the preliminary negotiations that would lead to the signing of the Anglo-Spanish peace at Somerset House the following August. Philip III sent a special ambassador to England to congratulate James on his accession, and a series of tussles between Juan de Tassis and his French counterpart ensued. As a recently-discovered document in the Archivo General de Simancas reveals, Anna of Denmark intervened personally to insure that de Tassis, and not the Frenchman, attended the masque. This was a clear signal of James and Anna's peace aims, which de Tassis conveyed to the King of Spain; moreover, he enclosed in his dispatch a text of Daniel's masque which he clearly considered both political intelligence and of interest to the theater-loving Hapsburg monarch. The Simancas text of the Daniel masque is a new version, hitherto unknown, which adds to our knowledge of the circumstances in which the first Stuart masque was performed. Here we present a transcription and annotated translation of both de Tassis' letter and the text of the masque he had compiled for Philip III. (B. C.-E. and M. H.)

Brief communication. Rain effect on the load of tephra deposits

Accumulation of tephra fallout produced during explosive eruptions can cause roof collapses in areas near the volcano, when the weight of the deposit exceeds some threshold value that depends on the quality of buildings. The additional loading of water that remains trapped in the tephra deposits due to rainfall can contribute to increasing the loading of the deposits on the roofs. Here we propose a simple approach to estimate an upper bound for the contribution of rain to the load of pyroclastic deposits that is useful for hazard assessment purposes. As case study we present an application of the method in the area of Naples, Italy, for a reference eruption from Vesuvius volcano.