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Abstract: In this work, the effects of the protozoan Neospora caninum on the bioenergetics, chemical composition, and elemental content of human brain microvascular endothelial cells (hBMECs) were investigated. We showed that N. caninum can impair cell mitochondrial (Mt) function and causes an arrest in host cell cycling at S and G2 phases. These adverse effects were also associated with altered expression of genes involved in Mt energy metabolism, suggesting Mt dysfunction caused by N. caninum infection. Fourier Transform Infrared (FTIR) spectroscopy analysis of hBMECs revealed alterations in the FTIR bands as a function of infection, where infected cells showed alterations in the absorption bands of lipid (2924 cm−1), amide I protein (1649 cm−1), amide II protein (1537 cm−1), nucleic acids and carbohydrates (1092 cm−1, 1047 cm−1, and 939 cm−1). By using quantitative synchrotron radiation X-ray fluorescence (μSR-XRF) imaging and quantification of the trace elements Zn, Cu and Fe, we detected an increase in the levels of Zn and Cu from 3 to 24 h post infection (hpi) in infected cells compared to control cells, but there were no changes in the level of Fe. We also used Affymetrix array technology to investigate the global alteration in gene expression of hBMECs and rat brain microvascular endothelial cells (rBMVECs) in response to N. caninum infection at 24 hpi. The result of transcriptome profiling identified differentially expressed genes involved mainly in immune response, lipid metabolism and apoptosis. These data further our understanding of the molecular events that shape the interaction between N. caninum and blood-brain-barrier endothelial cells.

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Abstract: Magmatic systems are dominated by five volatiles, namely H2O, CO2, F, Cl, and S (the igneous quintet). Multiple studies have measured partitioning of four out of these five volatiles (H2O, CO2, F, and Cl) between nominally volatile-free minerals and melts, whereas the partitioning of sulfur is poorly known. To better constrain the behavior of sulfur in igneous systems we measured the partitioning of sulfur between clinopyroxene and silicate melts over a range of pressure, temperature, and melt composition from 0.8 to 1.2 GPa, 1000 to 1240 °C, and 49 to 66 wt% SiO2 (13 measurements). Additionally, we determined the crystal-melt partitioning of sulfur for plagioclase (6 measurements), orthopyroxene (2 measurements), amphibole (2 measurements), and olivine (1 measurement) in some of these same run products. Experiments were performed at high and low oxygen fugacities, where sulfur in the melt is expected to be dominantly present as an S6+ or an S2– species, respectively. When the partition coefficient is calculated as the total sulfur in the crystal divided by the total sulfur in the melt, the partition coefficient varies from 0.017 to 0.075 for clinopyroxene, from 0.036 to 0.229 for plagioclase, and is a maximum of 0.001 for olivine and of 0.003 for orthopyroxene. The variation in the total sulfur partition coefficient positively correlates with cation-oxygen bond lengths in the crystals; the measured partition coefficients increase in the order: olivine < orthopyroxene < clinopyroxene ≤ amphibole and plagioclase. At high oxygen fugacities in hydrous experiments, the clinopyroxene/melt partition coefficients for total sulfur are only approximately one-third of those measured in low oxygen fugacity, anhydrous experiments. However when the partition coefficient is calculated as total sulfur in the crystal divided by S2– in the melt, the clinopyroxene/melt partition coefficients for experiments with melts between ~51 and 66 wt% SiO2 can be described by a single mean value of 0.063 ± 0.010 (1σ standard deviation about the mean). These two observations support the hypothesis that sulfur, as S2–, replaces oxygen in the crystal structure. The results of hydrous experiments at low oxygen fugacity and anhydrous experiments at high oxygen fugacity suggest that oxygen fugacity has a greater effect on sulfur partitioning than water. Although the total sulfur clinopyroxene-melt partition coefficients are affected by the Mg/(Mg+Fe) ratio of the crystal, partition coefficients calculated using S2– in the melt display no clear dependence upon the Mg# of the clinopyroxene. Both the bulk and the S 2– partition coefficients appear unaffected by IVAl in the clinopyroxene structure. No effect of anorthite content nor of iron concentration in the crystal was seen in the data for plagioclase-melt partitioning. The data obtained for orthopyroxene and olivine were too few to establish any trends. The partition coefficients of total sulfur and S 2– between the crystals studied and silicate melts are typically lower than those of fluorine, higher than those of carbon, and similar to those of chlorine and hydrogen. These sulfur partition coefficients can be combined with analyses of volatiles in nominally volatile-free minerals and previously published partition coefficients of H2O, C, F, and Cl to constrain the concentration of the igneous quintet, the five major volatiles in magmatic systems.

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Abstract: Microglia and astrocytes can quench metal toxicity to maintain tissue homeostasis, but with age, increasing glial dystrophy alongside metal dyshomeostasis may predispose the aged brain to acquire neurodegenerative diseases. The aim of the present study was to investigate age-related changes in brain metal deposition along with glial distribution in normal C57Bl/6J mice aged 2-, 6-, 19- and 27-months (n = 4/age). Using synchrotron-based X-ray fluorescence elemental mapping, we demonstrated age-related increases in iron, copper, and zinc in the basal ganglia (p < 0.05). Qualitative assessments revealed age-associated increases in iron, particularly in the basal ganglia and zinc in the white matter tracts, while copper showed overt enrichment in the choroid plexus/ventricles. Immunohistochemical staining showed augmented numbers of microglia and astrocytes, as a function of aging, in the basal ganglia (p < 0.05). Moreover, qualitative analysis of the glial immunostaining at the level of the fimbria and ventral commissure, revealed increments in the number of microglia but decrements in astroglia, in older aged mice. Upon morphological evaluation, aged microglia and astroglia displayed enlarged soma and thickened processes, reminiscent of dystrophy. Since glial cells have major roles in metal metabolism, we performed linear regression analysis and found a positive association between iron (R2 = 0.57, p = 0.0008), copper (R2 = 0.43, p = 0.0057), and zinc (R2 = 0.37, p = 0.0132) with microglia in the basal ganglia. Also, higher levels of iron (R2 = 0.49, p = 0.0025) and zinc (R2 = 0.27, p = 0.040) were correlated to higher astroglia numbers. Aging was accompanied by a dissociation between metal and glial levels, as we found through the formulation of metal to glia ratios, with regions of basal ganglia being differentially affected. For example, iron to astroglia ratio showed age-related increases in the substantia nigra and globus pallidus, while the ratio was decreased in the striatum. Meanwhile, copper and zinc to astroglia ratios showed a similar regional decline. Our findings suggest that inflammation at the choroid plexus, part of the blood-cerebrospinal-fluid barrier, prompts accumulation of, particularly, copper and iron in the ventricles, implying a compromised barrier system. Moreover, age-related glial dystrophy/senescence appears to disrupt metal homeostasis, likely due to induced oxidative stress, and hence increase the risk of neurodegenerative diseases.

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Abstract: Eudialyte group minerals (EGM) attract global interest as potential resources for High Field Strength Elements (HFSE, e.g. Zr, Nb, Ta, and Rare Earth Elements, REE), i.e. critical materials for modern technologies. They are particularly valued for their relative enrichment in the most critical lanthanides, i.e. Nd and heavy REE (Gd-Lu). However, REE substitution mechanisms into the EGM structure are still poorly understood. Light and heavy REE may occupy different sites and there may be ordering and/or defect clustering in the structure. This study uses X-ray Absorption Spectroscopy (XAS) to determine the structural state of REE in EGM from prospective eudialyte-bearing complexes. Yttrium K-edge and Nd L3-edge spectra were collected as proxies for heavy and light REE, respectively, and compared to natural and synthetic REE-bearing standards. Extended X-ray Absorption Fine Structure (EXAFS) data yield best fits for Y in six-fold coordination with Y-O distances of 2.24-2.32 Å, and a second coordination sphere comprising Fe, Na, Ca, Si and O at radial distances of 3.6-3.8 Å. These findings are consistent with dominant Y3+ substitution for Ca2+ on the octahedral M1 site in all samples studied, and exclude preferential substitution of Y3+ onto the smaller octahedral Z site or the large low-symmetry N4 site. Using lattice strain theory, we constructed relative partitioning models to predict site preferences of lanthanides we have not directly measured. The models predict that all REE are favoured on the Ca-dominant M1 site and that preferential partitioning of heavy over light REE increases in EGM containing significant Mn in the M1-octahedral rings (oneillite 3 subgroup). Thus, the flat REE profiles that make EGM such attractive exploration targets are not due to preferential partitioning of light and heavy REE onto different sites. Instead, local ordering of Mn- and Ca-occupied M1 sites may influence the capacity of EGM to accommodate heavy REE.

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Abstract: Prostatic zinc content is a known biomarker for discriminating normal healthy tissue from benign prostatic hyperplasia (BPH) and prostate cancer (PCa). Given that zinc content is not readily measured without a tissue biopsy, we have been exploring noninvasive imaging methods to detect these diagnostic differences using a zinc-responsive MRI contrast agent. During imaging studies in mice, we observed that a bolus of glucose stimulates secretion of zinc from the prostate of fasted mice. This discovery allowed the use of a Gd-based zinc sensor to detect differential zinc secretion in regions of healthy versus malignant prostate tissue in a transgenic adenocarcinoma mouse model of PCa. Here, we used a zinc-responsive MRI agent to detect zinc release across the prostate during development of malignancy and confirm the loss of total tissue zinc by synchrotron radiation X-ray fluorescence (μSR-XRF). Quantitative μSR-XRF results show that the lateral lobe of the mouse prostate uniquely accumulates high concentrations of zinc, 1.06 ± 0.08 mM, and that the known loss of zinc content in the prostate is only observed in the lateral lobe during development of PCa. Additionally, we confirm that lesions identified by a loss of zinc secretion indeed represent malignant neoplasia and that the relative zinc concentration in the lesion is reduced to 0.370 ± 0.001 mM. The μSR-XRF data also provided insights into the mechanism of zinc secretion by showing that glucose promotes movement of zinc pools (∼1 mM) from the glandular lumen of the lateral lobe of the mouse prostate into the stromal/smooth muscle surrounding the glands. Co-localization of zinc and gadolinium in the stromal/smooth muscle areas as detected by μSR-XRF confirm that glucose initiates secretion of zinc from intracellular compartments into the extracellular spaces of the gland where it binds to the Gd-based agent and albumin promoting MR image enhancement.