51 research outputs found
Accumulation of ambient phosphate into the periplasm of marine bacteria is proton motive force dependent
Bacteria acquire phosphate (Pi) by maintaining a periplasmic concentration below environmental levels. We recently described an extracellular Pi buffer which appears to counteract the gradient required for Pi diffusion. Here, we demonstrate that various treatments to outer membrane (OM) constituents do not affect the buffered Pi because bacteria accumulate Pi in the periplasm, from which it can be removed hypo-osmotically. The periplasmic Pi can be gradually imported into the cytoplasm by ATP-powered transport, however, the proton motive force (PMF) is not required to keep Pi in the periplasm. In contrast, the accumulation of Pi into the periplasm across the OM is PMF-dependent and can be enhanced by light energy. Because the conventional mechanism of Pi-specific transport cannot explain Pi accumulation in the periplasm we propose that periplasmic Pi anions pair with chemiosmotic cations of the PMF and millions of accumulated Pi pairs could influence the periplasmic osmolarity of marine bacteria
Structural state of rare earth elements in eudialyte-group minerals
This work was carried out under the NERC-funded SOS RARE consortium [grant NE/M010856/1 to AMB, NJH and AF]. We thank Diamond Light Source and KIT Karlsruhe Light Source for beam time at I18 [grants SP14793 and SP15903 to AMB and AF] and SUL-X, respectively. PG was funded by the People Programme (Marie Curie Actions) in the EU Seventh Framework Programme (FP7/2007-2013), REA grant agreement no. 609405 (COFUNDPostdocDTU).Eudialyte-group minerals (EGM) attract global interest as potential resources for high-field-strength elements (e.g. Zr, Nb, Ta, and rare-earth elements), 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 rare earth elements (Gd–Lu). However, rare earth element (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 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 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 the 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 measured directly. 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 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.Publisher PDFPeer reviewe
Impact of Neospora caninum infection on the bioenergetics and transcriptome of cerebrovascular endothelial cells
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
Implications of X-ray beam profiles on qualitative and quantitative synchrotron micro-focus X-ray fluorescence microscopy
Synchrotron radiation X-ray fluorescence microscopy is frequently used to investigate the spatial distribution of elements within a wide range of samples. Interrogation of heterogeneous samples that contain large concentration ranges has the potential to produce image artefacts due to the profile of the X-ray beam. The presence of these artefacts and the distribution of flux within the beam profile can significantly affect qualitative and quantitative analyses. Two distinct correction methods have been generated by referencing the beam profile itself or by employing an adaptive-thresholding procedure. Both methods significantly improve qualitative imaging by removing the artefacts without compromising the low-intensity features. The beam-profile correction method improves quantitative results but requires accurate two-dimensional characterization of the X-ray beam profile
Adsorption of rare earth elements in regolith-hosted clay deposits
Global resources of heavy Rare Earth Elements (REE) are dominantly sourced from Chinese regolith-hosted ion-adsorption deposits in which the REE are inferred to be weakly adsorbed onto clay minerals. Similar deposits elsewhere might provide alternative supply for these high-tech metals, but the adsorption mechanisms remain unclear and the adsorbed state of REE to clays has never been demonstrated in situ. This study compares the mineralogy and speciation of REE in economic weathering profiles from China to prospective regoliths developed on peralkaline rocks from Madagascar. We use synchrotron X-ray absorption spectroscopy to study the distribution and local bonding environment of Y and Nd, as proxies for heavy and light REE, in the deposits. Our results show that REE are truly adsorbed as easily leachable 8- to 9-coordinated outer-sphere hydrated complexes, dominantly onto kaolinite. Hence, at the atomic level, the Malagasy clays are genuine mineralogical analogues to those currently exploited in China
Metallome of cerebrovascular endothelial cells infected with Toxoplasma gondii using μ-XRF imaging and inductively coupled plasma mass spectrometry
In this study, we measured the levels of elements in human brain microvascular endothelial cells (ECs) infected with T. gondii. ECs were infected with tachyzoites of the RH strain, and at 6, 24, and 48 hours post infection (hpi), the intracellular concentrations of elements were determined using a synchrotron–microfocus X-ray fluorescence microscopy (μ-XRF) system. This method enabled the quantification of the concentrations of Zn and Ca in infected and uninfected (control) ECs at sub-micron spatial resolution. T. gondii-hosting ECs contained less Zn than uninfected cells only at 48 hpi (p 0.05). Inductively Coupled Plasma Mass Spectrometry (ICP-MS) analysis revealed infection-specific metallome profiles characterized by significant increases in the intracellular levels of Zn, Fe, Mn and Cu at 48 hpi (p < 0.01), and significant reductions in the extracellular concentrations of Co, Cu, Mo, V, and Ag at 24 hpi (p < 0.05) compared with control cells. Zn constituted the largest part (74%) of the total metal composition (metallome) of the parasite. Gene expression analysis showed infection-specific upregulation in the expression of five genes, MT1JP, MT1M, MT1E, MT1F, and MT1X, belonging to the metallothionein gene family. These results point to a possible correlation between T. gondii infection and increased expression of MT1 isoforms and altered intracellular levels of elements, especially Zn and Fe. Taken together, a combined μ-XRF and ICP-MS approach is promising for studies of the role of elements in mediating host–parasite interaction
A Comparative Study of Ultrasmall Calcium Carbonate Nanoparticles for Targeting and Imaging Atherosclerotic Plaque
therosclerosis is a complex disease that can lead to
life-threatening events, such as myocardial infarction and ischemic
stroke. Despite the severity of this disease, diagnosing plaque
vulnerability remains challenging due to the lack of effective
diagnostic tools. Conventional diagnostic protocols lack specificity
and fail to predict the type of atherosclerotic lesion and the risk of
plaque rupture. To address this issue, technologies are emerging,
such as noninvasive medical imaging of atherosclerotic plaque with
customized nanotechnological solutions. Modulating the biological
interactions and contrast of nanoparticles in various imaging
techniques, including magnetic resonance imaging, is possible
through the careful design of their physicochemical properties.
However, few examples of comparative studies between nanoparticles targeting different hallmarks of atherosclerosis exist to
provide information about the plaque development stage. Our work demonstrates that Gd (III)-doped amorphous calcium
carbonate nanoparticles are an effective tool for these comparative studies due to their high magnetic resonance contrast and
physicochemical properties. In an animal model of atherosclerosis, we compare the imaging performance of three types of
nanoparticles: bare amorphous calcium carbonate and those functionalized with the ligands alendronate (for micro-
calcification targeting) and trimannose (for inflammation targeting). Our study provides useful insights into ligand-mediated
targeted imaging of atherosclerosis through a combination of in vivo imaging, ex vivo tissue analysis, and in vitro targeting
experiments.We acknowledge M. Spuch for his scientific drawings and the
Basque Government for the R&D Project in Health (grant
number 2022333041). S.C.R. acknowledges the Spanish
Ministerio de Ciencia e Innovación (MCIN)/Agencia Estatal
de Investigación (AEI) Grant PID2019-106139RA-100 funded
by MCIN/AEI/10.13039/501100011033 and the Ramon y
Cajal Grant RYC2020-030241-I. C.S.C. acknowledges financial
support from the Spanish State Research Agency (grant
PID2020-118176RJ-I100), and the Gipuzkoa Foru Aldundia
(Gipuzkoa Fellows program; grant number 2019-FELL-
000018-01/62/2019). This work was performed under the
Severo Ochoa Centers of Excellence Program of the Spanish
State Research Agency − Grant No. CEX2018-000867-S
(DIPC). SXRF analysis was carried out with the support of
Diamond Light Source, beamline I18 (proposal SP27720).
J.R.C. is funded by MCIN/AEI/10.13039/501100011033
(PID2021-123238OB-I00) and from La Caixa Foundation
(Health Research Call 2020: HR20-00075). A.M.G. and C.U.
acknowledge the Spanish Ministerio de Ciencia e Innovación
(MCIN)/Agencia Estatal de Investigación (AEI) Grant:
PID2021-122504NB-I00 funded by MCIN/AEI/10.13039/
501100011033 and by “ERDF A way of making Europe.
W.J.P. acknowledges funding from the Cluster of Excellence
“Advanced Imaging of Matter” of the Deutsche Forschungsge-
meinschaft (DFG) - EXC 2056 - project ID 390715994. F.H.
acknowledges MCIN (PID2019-104059RB-I00) and M.J.S.G.
the Spanish Ministerio de Educación y Formación Profesional
(PRE2018-083691).
REFERENCES
(1) Libby, P. The changing landscape of atherosclerosPeer reviewe
Combining μXANES and μXRD mapping to analyse the heterogeneity in calcium carbonate granules excreted by the earthworm Lumbricus terrestris
The use of fluorescence full spectral micro-X-ray absorption near-edge structure (μXANES) mapping is becoming more widespread in the hard energy regime. This experimental method using the Ca K-edge combined with micro-X-ray diffraction (μXRD) mapping of the same sample has been enabled on beamline I18 at Diamond Light Source. This combined approach has been used to probe both long- and short-range order in calcium carbonate granules produced by the earthworm Lumbricus terrestris. In granules produced by earthworms cultured in a control artificial soil, calcite and vaterite are observed in the granules. However, granules produced by earthworms cultivated in the same artificial soil amended with 500 p.p.m. Mg also contain an aragonite. The two techniques, μXRD and μXANES, probe different sample volumes but there is good agreement in the phase maps produced
Microcalcification crystallography as a potential marker of DCIS recurrence
Ductal carcinoma in-situ (DCIS) accounts for 20-25% of all new breast cancer diagnoses. DCIS has an uncertain risk of progression to invasive breast cancer and a lack of predictive biomarkers may result in relatively high levels (~ 75%) of overtreatment. To identify unique prognostic biomarkers of invasive progression, crystallographic and chemical features of DCIS microcalcifications have been explored. Samples from patients with at least 5-years of follow up and no known recurrence (174 calcifications in 67 patients) or ipsilateral invasive breast cancer recurrence (179 microcalcifications in 57 patients) were studied. Significant differences were noted between the two groups including whitlockite relative mass, hydroxyapatite and whitlockite crystal maturity and, elementally, sodium to calcium ion ratio. A preliminary predictive model for DCIS to invasive cancer progression was developed from these parameters with an AUC of 0.797. These results provide insights into the differing DCIS tissue microenvironments, and how these impact microcalcification formation. [Abstract copyright: © 2023. The Author(s).
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