Hyperaccumulators are attractive models for studying metal(loid) homeostasis, and probing the spatial distribution and coordination chemistry of metal(loid)s in their tissues is important for ...advancing our understanding of their ecophysiology. X-ray elemental mapping techniques are unique in providing in situ information, and with appropriate sample preparation offer results true to biological conditions of the living plant. The common platform of these techniques is a reliance on characteristic X-rays of elements present in a sample, excited either by electrons (scanning/transmission electron microscopy), protons (proton-induced X-ray emission) or X-rays (X-ray fluorescence microscopy). Elucidating the cellular and tissue-level distribution of metal(loid)s is inherently challenging and accurate X-ray analysis places strict demands on sample collection, preparation and analytical conditions, to avoid elemental redistribution, chemical modification or ultrastructural alterations. We compare the merits and limitations of the individual techniques, and focus on the optimal field of applications for inferring ecophysiological processes in hyperaccumulator plants. X-ray elemental mapping techniques can play a key role in answering questions at every level of metal(loid) homeostasis in plants, from the rhizosphere interface, to uptake pathways in the roots and shoots. Further improvements in technological capabilities offer exciting perspectives for the study of hyperaccumulator plants into the future.
Immune function of the serosa in hemimetabolous insect eggs Jacobs, Chris G C; van der Hulst, Remy; Chen, Yen-Ta ...
Philosophical transactions of the Royal Society of London. Series B. Biological sciences,
12/2022, Letnik:
377, Številka:
1865
Journal Article
Recenzirano
Odprti dostop
Insects comprise more than a million species and many authors have attempted to explain this success by evolutionary innovations. A much overlooked evolutionary novelty of insects is the serosa, an ...extraembryonic epithelium around the yolk and embryo. We have shown previously that this epithelium provides innate immune protection to eggs of the beetle
It remained elusive, however, whether this immune competence evolved in the
lineage or is ancestral to all insects. Here, we expand our studies to two hemimetabolous insects, the bug
and the swarming grasshopper
. For
, RNA sequencing reveals an extensive response upon infection, including the massive upregulation of antimicrobial peptides (AMPs). We demonstrate antimicrobial activity of these peptides using
bacterial growth assays and describe two novel AMP families called Serosins and Ovicins. For both insects, quantitative polymerase chain reaction shows immune competence of the eggs when the serosa is present, and
hybridizations demonstrate that immune gene expression is localized in the serosa. This first evidence from hemimetabolous insect eggs suggests that immune competence is an ancestral property of the serosa. The evolutionary origin of the serosa with its immune function might have facilitated the spectacular radiation of the insects. This article is part of the theme issue 'Extraembryonic tissues: exploring concepts, definitions and functions across the animal kingdom'.
The 40year history of nuclear microscopy has seen sustained progress in the development of technology needed to improve PIXE analysis and trace element imaging performance. Focussing systems have ...been developed for improved spatial resolution, detector systems have evolved to collect more signal, full-spectral scanning data acquisition approaches have been devised. The complexity of PIXE spectra has driven the development of techniques for fitting numerous overlapping components in spectra for quantitative analysis, methods have been developed for specialized problems in geology, such as the analysis of fluid and melt inclusions in minerals, and techniques for the deconvolution of elemental components in full-spectral scanning data sets have been developed to produce accurate element images. The future of nuclear microscopy using PIXE is promising. Lens system approaches have evolved and point towards ‘full bore’ acceptance, optimal matching to accelerator emittance, high current density and sub-μm spatial resolution using many nA beam currents. Detector arrays and integrated data acquisition and scanning systems are emerging that can collect all events across a large solid-angle collection area and process these events for element image display in real-time. The combination of these advances provides a path to greatly enhanced sensitivity for PIXE analysis and imaging and a more productive user experience. The emergence of detector array approaches for scattered particles and reaction products, and the development of software tools for coupled PIXE-RBS data reduction, suggest a path towards complementary RBS and NRA tools. The stage is set for an exciting and productive future for PIXE imaging on the nuclear microprobe.
Metals and metalloids play a key role in plant and other biological systems as some of them are essential to living organisms and all can be toxic at high concentrations. It is therefore important to ...understand how they are accumulated, complexed and transported within plants. In situ imaging of metal distribution at physiological relevant concentrations in highly hydrated biological systems is technically challenging. In the case of roots, this is mainly due to the possibility of artifacts arising during sample preparation such as cross sectioning. Synchrotron x-ray fluorescence microtomography has been used to obtain virtual cross sections of elemental distributions. However, traditionally this technique requires long data acquisition times. This has prohibited its application to highly hydrated biological samples which suffer both radiation damage and dehydration during extended analysis. However, recent advances in fast detectors coupled with powerful data acquisition approaches and suitable sample preparation methods can circumvent this problem. We demonstrate the heightened potential of this technique by imaging the distribution of nickel and zinc in hydrated plant roots. Although 3D tomography was still impeded by radiation damage, we successfully collected 2D tomograms of hydrated plant roots exposed to environmentally relevant metal concentrations for short periods of time. To our knowledge, this is the first published example of the possibilities offered by a new generation of fast fluorescence detectors to investigate metal and metalloid distribution in radiation-sensitive, biological samples.
► Extended previous longitudinal research examining personality and ideology. ► Examined the bidirectional associations between these dimensions over 9
months. ► Included Big-Five personality, Social ...Dominance Orientation and Right-Wing Authoritarianism. ► Low Agreeableness predicted SDO and Openness to Experience predicted RWA over time. ► RWA and SDO did not predict reciprocal prospective change in personality.
A full cross-lagged panel design examined the bidirectional effects of the Big-Five personality dimensions on Social Dominance Orientation (SDO) and Right-Wing Authoritarianism (RWA) over 9
months (
N
=
190 undergraduates). Consistent with the Dual Process Cognitive-Motivational Model, SDO and RWA exhibited markedly different personality bases. Low Agreeableness predicted change in the motivational goal for group-based dominance and superiority (SDO), whereas Openness to Experience predicted change in the motivational goal for social cohesion and collective security (RWA). Extending previous longitudinal research, this study indicates that the effect of personality on ideology is unidirectional, as RWA and SDO did not predict reciprocal prospective change in broad-bandwidth personality. These findings are consistent with a model in which relatively stable broad-bandwidth personality traits shape ideological attitudes over even relatively short time periods, and not the reverse.
"Herbarium X-ray Fluorescence (XRF) Ionomics" is a new quantitative approach for extracting the elemental concentrations from herbarium specimens using handheld XRF devices. These instruments are ...principally designed for dense sample material of infinite thickness (such as rock or soil powder), and their built-in algorithms and factory calibrations perform poorly on the thin dry plant leaves encountered in herbaria. While empirical calibrations have been used for 'correcting' measured XRF values post hoc, this approach has major shortcomings. As such, a universal independent data analysis pipeline permitting full control and transparency throughout the quantification process is highly desirable. Here we have developed such a pipeline based on Dynamic Analysis as implemented in the GeoPIXE package, employing a Fundamental Parameters approach requiring only a description of the measurement hardware and derivation of the sample areal density, based on a universal standard.
The new pipeline was tested on potassium, calcium, manganese, iron, cobalt, nickel, and zinc concentrations in dry plant leaves. The Dynamic Analysis method can correct for complex X-ray interactions and performs better than both the built-in instrument algorithms and the empirical calibration approach. The new pipeline is also able to identify and quantify elements that are not detected and reported by the device built-in algorithms and provides good estimates of elemental concentrations where empirical calibrations are not straightforward.
The new pipeline for processing XRF data of herbarium specimens has a greater accuracy and is more robust than the device built-in algorithms and empirical calibrations. It also gives access to all elements detected in the XRF spectrum. The new analysis pipeline has made Herbarium XRF approach even more powerful to study the metallome of existing plant collections.
The XFM beamline at the Australian Synchrotron Howard, Daryl L.; de Jonge, Martin D.; Afshar, Nader ...
Journal of synchrotron radiation,
September 2020, 2020-09-01, 20200901, Letnik:
27, Številka:
5
Journal Article
Recenzirano
The X‐ray fluorescence microscopy (XFM) beamline is an in‐vacuum undulator‐based X‐ray fluorescence (XRF) microprobe beamline at the 3 GeV Australian Synchrotron. The beamline delivers hard X‐rays in ...the 4–27 keV energy range, permitting K emission to Cd and L and M emission for all other heavier elements. With a practical low‐energy detection cut‐off of approximately 1.5 keV, low‐Z detection is constrained to Si, with Al detectable under favourable circumstances. The beamline has two scanning stations: a Kirkpatrick–Baez mirror microprobe, which produces a focal spot of 2 µm × 2 µm FWHM, and a large‐area scanning `milliprobe', which has the beam size defined by slits. Energy‐dispersive detector systems include the Maia 384, Vortex‐EM and Vortex‐ME3 for XRF measurement, and the EIGER2 X 1 Mpixel array detector for scanning X‐ray diffraction microscopy measurements. The beamline uses event‐mode data acquisition that eliminates detector system time overheads, and motion control overheads are significantly reduced through the application of an efficient raster scanning algorithm. The minimal overheads, in conjunction with short dwell times per pixel, have allowed XFM to establish techniques such as full spectroscopic XANES fluorescence imaging, XRF tomography, fly scanning ptychography and high‐definition XRF imaging over large areas. XFM provides diverse analysis capabilities in the fields of medicine, biology, geology, materials science and cultural heritage. This paper discusses the beamline status, scientific showcases and future upgrades.
The X‐ray fluorescence microscopy (XFM) beamline at the Australian Synchrotron specializes in the spatially resolved detection and speciation determination of elements at the micrometre length scale. The status of its various operational modes and future upgrades are presented.
The fern Dicranopteris linearis is a hyperaccumulator of rare earth elements (REEs), aluminium (Al) and silicon (Si). However, the physiological mechanisms of tissue-level tolerance of high ...concentrations of REE and Al, and possible interactions with Si, are currently incompletely known.
A particle-induced X-ray emission (μPIXE) microprobe with the Maia detector, scanning electron microscopy with energy-dispersive spectroscopy and chemical speciation modelling were used to decipher the localization and biochemistry of REEs, Al and Si in D. linearis during uptake, translocation and sequestration processes.
In the roots >80 % of REEs and Al were in apoplastic fractions, among which the REEs were most significantly co-localized with Si and phosphorus (P) in the epidermis. In the xylem sap, REEs were nearly 100 % present as REEH3SiO42+, without significant differences between the REEs, while 24-45 % of Al was present as Al-citrate and only 1.7-16 % Al was present as AlH3SiO42+. In the pinnules, REEs were mainly concentrated in necrotic lesions and in the epidermis, and REEs and Al were possibly co-deposited within phytoliths (SiO2). Different REEs had similar spatial localizations in the epidermis and exodermis of roots, the necrosis, veins and epidermis of pinnae of D. linearis.
We posit that Si plays a critical role in REE and Al tolerance within the root apoplast, transport within the vascular bundle and sequestration within the blade of D. linearis.
Electrical micro-junctions in metal sulfides drive electrochemical reactions with passing gold-bearing fluids, resulting in the deposition of gold, even from under-saturated ore fluids. Understanding ...the role micro-junctions play in the deposition of gold requires (a) imaging the electric field distribution of a galvanic couple near the surface to qualify the existence of an active micro-geo-battery and (b) correlating it with gold precipitation on the p-type cathode side of the junction by mapping the host at minor and trace levels. Here we report on correlating electron back scattered diffraction (EBSD), particle induced X-ray emission (PIXE) elemental maps including micron-scaled gold hot spots with laser beam induced current (LBIC) photocurrent maps of galvanic coupling in natural arsenian pyrite from the Otago Schist in New Zealand. The results provide convincing evidence that sulphide electrochemical interactions can lead to gold electro-deposition. We finish by discussing a simplistic model of the processes involved in reference to the original model of Möller and Kersten (Miner Deposita 29(5):404–413. 1994), and discuss the effects of temperature in light of recent-reported evidence of electrochemical gold deposition in the formation of hydrothermal gold deposits.
Accumulation of arsenic (As) within plant tissues represents a human health risk, but there remains much to learn regarding the speciation of As within plants.
We developed synchrotron-based ...fluorescence-X-ray absorption near-edge spectroscopy (fluorescence-XANES) imaging in hydrated and fresh plant tissues to provide laterally resolved data on the in situ speciation of As in roots of wheat (Triticum aestivum) and rice (Oryza sativa) exposed to 2 μM As(V) or As(III).
When exposed to As(V), the As was rapidly reduced to As(III) within the root, with As(V) calculated to be present only in the rhizodermis. However, no uncomplexed As(III) was detected in any root tissues, because of the efficient formation of the As(III)–thiol complex – this As species was calculated to account for all of the As in the cortex and stele. The observation that uncomplexed As(III) was below the detection limit in all root tissues explains why the transport of As to the shoots is low, given that uncomplexed As(III) is the major As species transported within the xylem and phloem.
Using fluorescence-XANES imaging, we have provided in situ data showing the accumulation and transformation of As within hydrated and fresh root tissues.
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